Medium, apparatus, and method related to encryption resultant information

Abstract

A disk-shaped recording medium includes a transplant substrate, and an optical recording layer formed on the transparent substrate. A light source emits light. An optical head is operative for applying the light to the optical recording layer from the light source via the transparent substrate, for focusing the light on the optical recording layer, and for reproducing information from the optical recording layer. A position detecting device is operative for detecting at least one of a pit depth and a physical position of information which has a first given relation with a specified address and which is recorded on the recording medium, and for generating first positional information representing at least one of the pit depth and the physical position. A previously-recorded secret code is reproduced from the recording medium. The secret code represents second positional information. The secret code is decoded into the second positional information. The second positional information represents at least one of a predetermined reference pit depth and a predetermined reference physical position. The first positional information and the second positional information are collated, and a check is made as to whether or not the first positional information and the second positional information are in a second given relation. When the first positional information and the second positional information are not in the second given relation, one of outputting of a reproduced signal of the recording medium, operation of a program stored in the recording medium, and decoding of the secret code is stopped.

Claims

What is claimed is:

1. A recording medium having a specified area storing encryption-resultant information resulting from encryption of original information in response to a specified encrypting signal, the original information representing a physical feature of the recording medium.

2. A recording medium as recited in claim 1, wherein the specified encrypting signal includes a signal representing a public key.

3. A recording medium as recited in claim 2, wherein the signal representing the public key includes an RSA signal.

4. A recording medium as recited in claim 1, wherein the original information is optically detectable by an optical detecting means.

5. A recording medium as recited in claim 1, wherein the original information is optically readable by an optical head.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an apparatus for recording and reproducing information on and from a recording medium.

2. Description of the Prior Art

Japanese published unexamined patent applications 56-163536. 57-6446, 57-212642, and 60-70543 disclose a recording medium having both a magnetic recording portion and an optical recording portion.

Japanese published unexamined patent application 2-179951 discloses a recording medium which has an optical recording portion and a magnetic recording portion at opposite sides thereof respectively. Japanese patent application 2-179951 also discloses an apparatus which includes an optical head facing the optical recording portion of the recording medium for reading out information from the optical recording portion, a magnetic head facing the magnetic recording portion of the recording medium for recording and reproducing information into and from the magnetic recording portion, and a mechanism for moving at least one of the optical head and the magnetic head in accordance with rotation of the recording medium. In the apparatus of Japanese patent application 2-179951, during the processing of the information read out from the magnetic recording portion, a decision is made as to whether or not the information recorded on the optical recording portion is necessary, and a step of reading out the information from the optical recording portion is executed when the information on the optical recording portion is decided to be necessary.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an improved recording and reproducing apparatus.

A first aspect of this invention provides a recording and reproducing apparatus for use with a disk-shaped recording medium which includes a transparent substrate and an optical recording layer formed on the transparent substrate, the apparatus comprising a light source for emitting light; an optical head for applying the light to the optical recording layer from the light source via the transparent substrate, for focusing the light on the optical recording layer, and for reproducing information from the optical recording layer; a position detecting means for detecting at least one of a pit depth and a physical position of information which has a first given relation with a specified address and which is recorded on the recording medium, and for generating first positional information representing at least said one of the pit depth and the physical position; a reproducing means for reproducing a previously-recorded secret code from the recording medium, the secret code representing second positional information, and for decoding the secret code into the second positional information, the second positional information representing at least one of a predetermined reference pit depth and a predetermined reference physical position; a collating means for collating the first positional information and the second positional information, and for checking whether or not the first positional information and the second positional information are in a second given relation; and a stopping means for, in cases where the first positional information and the second positional information are not in the second given relation, stopping at least one of outputting of a reproduced signal of the recording medium, operation of a program stored in the recording medium, and decoding of the secret code.

A second aspect of this invention provides a recording and reproducing apparatus for use with a disk-shaped recording medium which includes a transparent substrate, and an optical recording layer and a magnetic recording layer formed on the transparent substrate, the apparatus comprising a light source for emitting light; an optical head for applying the light to the optical recording layer from the light source via the transparent substrate, for focusing the light on the optical recording layer, and for reproducing information from the optical recording layer; a magnetic head for recording a signal on the magnetic recording layer or reproducing a signal from the magnetic recording layer; a position detecting means for detecting a position of an address information recorded on the recording medium, and for generating first positional information representing said detected position of the address information; a reproducing means for reproducing a previously-recorded secret code from the recording medium, the secret code representing second positional information, and for decoding the secret code into the second positional information, the second positional information representing a predetermined reference position: a collating means for collating the first positional information and the second positional information, and for checking whether or not the first positional information and the second positional information are in a given relation: and a stopping means for, in cases where the first positional information and the second positional information are not, in the given relation, stopping at least one of outputting of a reproduced signal of the recording medium, operation, and decoding of the secret code.

BRIEF DESCRIPTION THE DRAWINGS

FIG. 1 is a block diagram of a recording and reproducing apparatus according to a first embodiment of this invention.

FIG. 2 is an enlarged view of an optical recording head portion in the first embodiment.

FIG. 3 is an enlarged view of a head portion in the first embodiment.

FIG. 4 is an enlarged view of a head portion in the first embodiment as viewed in a tracking direction.

FIG. 5 is an enlarged view of a magnetic head portion in the first embodiment.

FIGS. 6(a)-6(g) are a timing chart of magnetic recording in the first embodiment.

FIG. 7 is a sectional view of a recording medium in the first embodiment.

FIG. 8 is a sectional view of a recording medium in the first embodiment.

FIG. 9 is a sectional view of a recording medium in the first embodiment.

FIG. 10 is a sectional view of a recording portion in the first embodiment.

FIG. 11 is a sectional view of a recording portion in the first embodiment.

FIG. 12 is a sectional view of a recording portion in the first embodiment.

FIG. 13 is a sectional view of a recording portion in the first embodiment.

FIG. 14 is a sectional view of a recording portion in the first embodiment.

FIG. 15 is a perspective view of a cassette in the first embodiment.

FIG. 16 is a perspective view of a recording and reproducing apparatus in the first embodiment.

FIG. 17 is a block diagram of a recording and reproducing apparatus according to the first embodiment.

FIG. 18 is a perspective view of a game machine in the first embodiment.

FIG. 19 is a block diagram of a recording and reproducing apparatus according to a second embodiment of this invention.

FIG. 20 is an enlarged view of a magnetic head portion in the second embodiment.

FIG. 21 is an enlarged view of a magnetic head portion in the second embodiment.

FIG. 22 is an enlarged view of a magnetic head portion in the second embodiment.

FIG. 23 is an enlarged view of a recording portion in a third embodiment of this invention.

FIG. 24 is a block diagram of a recording and reproducing apparatus according to a fourth embodiment of this invention.

FIG. 25 is an enlarged view of a magnetic recording portion in the fourth embodiment.

FIG. 26 is an enlarged view of a magneto-optical recording portion in the fourth embodiment.

FIG. 27 is a sectional view of a recording portion in the fourth embodiment.

FIG. 28 is a flowchart of a program in the fourth embodiment.

FIG. 29 is a flowchart of a program in the fourth embodiment.

FIG. 30(a) is a sectional view of conditions where a magneto-optical disk is placed in an operable position in the fourth embodiment.

FIG. 30(b) is a sectional view of conditions where a CD is placed in an operable position in the fourth embodiment.

FIG. 31 is an enlarged view of a magneto-optical recording portion in the fourth embodiment.

FIG. 32 is a block diagram of a recording and reproducing apparatus according to a fifth embodiment of this invention.

FIG. 33 is an enlarged view of a magnetic recording portion in the fifth embodiment.

FIG. 34 is an enlarged view of a magneto-optical recording portion in the fifth embodiment.

FIG. 35 is an enlarged view of a magneto-optical recording portion in the fifth embodiment.

FIG. 36 is an enlarged view of a magnetic recording portion in the fifth embodiment.

FIG. 37 is an enlarged view of a magneto-optical recording portion in the fifth embodiment.

FIG. 38 is a block diagram of a recording and reproducing apparatus according to a sixth embodiment of this invention.

FIG. 39 is a block diagram of a magnetic recording portion in the sixth embodiment.

FIG. 40 is an enlarged view of a magnetic field modulating portion in the sixth embodiment.

FIG. 41 is a top view of a magnetic recording portion in the sixth embodiment.

FIG. 42 is a top view of a magnetic recording portion in the sixth embodiment.

FIG. 43 is an enlarged view of a magnetic recording portion in the sixth embodiment.

FIG. 44 is an enlarged view of a magnetic field modulating portion in the sixth embodiment.

FIG. 45(a) is a top view of a disk cassette in a seventh embodiment of this invention.

FIG. 45(b) is a top view of a disk cassette in the seventh embodiment.

FIG. 46(a) is a top view of a disk cassette in the seventh embodiment.

FIG. 46(b) is a top view of a disk cassette in the seventh embodiment.

FIG. 47(a) is a top view of a disk cassette in the seventh embodiment.

FIG. 47(b) is a top view of a disk cassette in the seventh embodiment.

FIG. 48(a) is a top view of a disk cassette in the seventh embodiment.

FIG. 48(b) is a top view of a disk cassette in the seventh embodiment.

FIG. 49(a) is a top view of a liner and a portion around the liner in the seventh embodiment.

FIG. 49(b) is a top view of a liner and a portion around the liner in the seventh embodiment.

FIG. 49(c) is a top view of a liner and a portion around the liner in the seventh embodiment.

FIG. 50(a) is a top view of a liner and a portion around the liner in the seventh embodiment.

FIG. 50(b) is a top view of a liner and a portion around the liner in the seventh embodiment.

FIG. 50(c) is a transversely sectional view of a liner portion in the seventh embodiment.

FIG. 50(d) is a transversely sectional view of a disk cassette in the seventh embodiment.

FIG. 51 is a transversely sectional view of conditions where liner pin insertion is off in the seventh embodiment.

FIG. 52 is a transversely sectional view of conditions where liner pin insertion is on in the seventh embodiment.

FIG. 53(a) is a transversely sectional view of conditions where liner pin insertion is off in the seventh embodiment.

FIG. 53(b) is a transversely sectional view of conditions where liner pin insertion is on in the seventh embodiment.

FIG. 54(a) is a transversely sectional view of conditions where magnetic head mounting is off in the seventh embodiment.

FIG. 54(b) is a transversely sectional view of conditions where magnetic head mounting is on in the seventh embodiment.

FIG. 55(a) is a transversely sectional view of conditions where magnetic head mounting is off in the seventh embodiment.

FIG. 55(b) is a transversely sectional view of conditions where magnetic head mounting is on in the seventh embodiment.

FIG. 56 is a top view of a recording medium in the seventh embodiment.

FIG. 57(a) is a transversely sectional view of conditions where liner pin insertion is off in the seventh embodiment.

FIG. 57(b) is a transversely sectional view of conditions where liner pin insertion is on in the seventh embodiment.

FIG. 58 is a sectional view of a liner pin front portion which assumes an off state in the seventh embodiment.

FIG. 59 is a sectional view of a liner pin front portion which assumes an on state in the seventh embodiment.

FIG. 60 is a transversely sectional view of a liner pin which assumes an off state in the seventh embodiment.

FIG. 61 is a transversely sectional view of a liner pin which assumes an on state in the seventh embodiment.

FIG. 62 is a sectional view of a front portion in the case where a liner pin is off in the seventh embodiment.

FIG. 63 is a sectional view of a front portion in the case where a liner pin is on in the seventh embodiment.

FIG. 64 is a sectional view of a front portion in the case where a liner pin is off in the seventh embodiment.

FIG. 65 is a sectional view of a front portion in the case where a liner pin is on in the seventh embodiment.

FIG. 66 is a sectional view of a front portion in the case where a liner pin is off in the seventh embodiment.

FIG. 67 is a sectional view of a front portion in the case where a liner pin is off and is inactive in the seventh embodiment.

FIG. 68(a) is a top view of a disk cassette in an eighth embodiment of this invention.

FIG. 68(b) is a top view of a disk cassette in the eighth embodiment.

FIG. 69(a) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is off in the eighth embodiment.

FIG. 69(b) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is on in the eighth embodiment.

FIG. 70(a) is a top view of a disk cassette in the eighth embodiment.

FIG. 70(b) is a top view of a disk cassette in the eighth embodiment.

FIG. 70(c) is a top view of a disk cassette in the eighth embodiment.

FIG. 71 is a transversely sectional view of a liner pin and a disk cassette in the eighth embodiment.

FIG. 72(a) is a transversely sectional view of a portion around a liner pin in the eighth embodiment.

FIG. 72(b) is a transversely sectional view of a portion around a liner pin in the case where a conventional cassette is placed in an operable position in the eighth embodiment.

FIG. 73(a) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is off in the eighth embodiment.

FIG. 73(b) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is on in the eighth embodiment.

FIG. 74(a) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is off in the eighth embodiment.

FIG. 74(b) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is on in the eighth embodiment.

FIG. 75 is a top view of a disk cassette in a ninth embodiment of this invention.

FIG. 76 is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is off in the ninth embodiment.

FIG. 77 is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is on in the ninth embodiment.

FIG. 78(a) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is off in the ninth embodiment.

FIG. 78(b) is a transversely sectional view of a portion around a liner pin in the case where liner pin insertion is on in the ninth embodiment.

FIG. 79(a) is an illustration of a tracking principle which occurs in the absence of correction in a tenth embodiment of this invention.

FIG. 79(b) is an illustration of a tracking principle which occurs in the absence of correction in the tenth embodiment.

FIG. 80(a) is a view of tracking conditions of an optical head in the tenth embodiment.

FIG. 80(b) is a view of tracking conditions of an optical head in the tenth embodiment.

FIG. 81(a) is an illustration of an offset amount of an optical track on a disk in the tenth embodiment.

FIG. 81(b) is an illustration of an offset amount of an optical track on a disk in the tenth embodiment.

FIG. 81(c) is an illustration of a tracking error signal in the tenth embodiment.

FIG. 82(a) is a view of tracking conditions of an optical head which occur in the absence of correction in the tenth embodiment.

FIG. 82(b) is a view of tracking conditions of an optical head which occur in the presence of correction in the tenth embodiment.

FIG. 83 is an illustration of a reference track in the tenth embodiment.

FIG. 84(a) is a side view of a slider in the case of an ON state in the tenth embodiment.

FIG. 84(b) is a side view of a slider in the case of an OFF state in the tenth embodiment.

FIG. 85(a) is a side view of a slider portion in the case where magnetic recording is OFF in the tenth embodiment.

FIG. 85(b) is a side view of a slider portion in the case where magnetic recording is ON in the tenth embodiment.

FIG. 86 is an illustration of the correspondence relation between an address and a position on a disk in the tenth embodiment.

FIG. 87 is a block diagram of a magnetic recording portion in an eleventh embodiment of this invention.

FIG. 88(a) is a transversely sectional view of a magnetic head in the eleventh embodiment.

FIG. 88(b) is a bottom view of a magnetic head in the eleventh embodiment.

FIG. 88(c) is a bottom view of another magnetic head in the eleventh embodiment.

FIG. 89 is an illustration of a spiral-shaped recording format in the eleventh embodiment.

FIG. 90 is an illustration of a recording format of a guard band in the eleventh embodiment.

FIG. 91 is an illustration of a data structure in the eleventh embodiment.

FIGS. 92(a)A-92(a)S are a timing chart of recording in the eleventh embodiment.

FIGS. 92(b)A-92(b)S are a timing chart of simultaneous recording by two heads in the eleventh embodiment.

FIG. 93 is a block diagram of a reproducing portion in the eleventh embodiment.

FIGS. 94(a)-94(c) are an illustration of a data arrangement in the eleventh embodiment.

FIG. 95 is a flowchart of traverse control in the eleventh embodiment.

FIG. 96 is an illustration of a cylindrical recording format in the eleventh embodiment.

FIG. 97 is an illustration of the relation between a traverse gear rotation number and a radius in the eleventh embodiment.

FIG. 98 is an illustration of an optical recording surface format in the eleventh embodiment.

FIG. 99 is an illustration of a recording format in the presence of compatibility with a lower level apparatus in the eleventh embodiment.

FIG. 100 is an illustration of the correspondence relation between an optical recording surface and a magnetic recording surface in the eleventh embodiment.

FIGS. 101(a) and 101(b) are a perspective view of a recording medium in a twelfth embodiment of this invention.

FIG. 102 is a perspective view of a recording medium in the twelfth embodiment.

FIGS. 103(a)-103(f) are a transversely sectional view of a recording medium which occurs at film forming and printing steps in the twelfth embodiment.

FIGS. 104(a)-104(f) are a transversely sectional view of a recording medium which occurs at film forming and printing steps in the twelfth embodiment.

FIG. 105 is a perspective view of a manufacturing system in a state corresponding to an application step in the twelfth embodiment.

FIGS. 106(a)-106(c) are a transversely sectional view of a recording medium at application and transfer steps in the twelfth embodiment.

FIGS. 107(a)-107(e) are an illustration of steps of manufacturing a recording medium in the twelfth embodiment.

FIGS. 108(a) and 108(b) arre a transversely sectional view of a recording medium at application and transfer steps in the twelfth embodiment.

FIG. 109 is a perspective view of a manufacturing system in a state corresponding to an application step in the twelfth embodiment.

FIG. 110 is a block diagram of a recording and reproducing apparatus according to a thirteenth embodiment of this invention.

FIG. 111 is a transversely sectional view of a portion around a magnetic head in the thirteenth embodiment.

FIG. 112 is an illustration of the relation between a head gap length and an attenuation amount (dB) in the thirteenth embodiment.

FIG. 113 is a top view of a magnetic track in the thirteenth embodiment.

FIG. 114 is a transversely sectional view of a portion around a magnetic head in the thirteenth embodiment.

FIGS. 115(a) and 115(b) are a transversely sectional view of conditions where a recording medium is placed in an operable position.

FIG. 116 is an illustration of the relation between a relative noise amount and a distance between an optical head and a magnetic head in the twelfth and thirteenth embodiments.

FIG. 117 is a transverse sectional view of a head traverse portion in the thirteenth embodiment.

FIG. 118 is a top view of a head traverse portion in the thirteenth embodiment.

FIG. 119 is a transversely sectional view of another head traverse portion in the thirteenth embodiment.

FIG. 120 is a transversely sectional view of another head traverse portion in the thirteenth embodiment.

FIG. 121 is an illustration of the intensities of magnetic fields generated by various home-use appliances.

FIG. 122 is an illustration of a recording format on a recording medium in the thirteenth embodiment.

FIG. 123 is an illustration of a recording format on a recording medium in a normal mode in the thirteenth embodiment.

FIG. 124 is an illustration of a recording format on a recording medium in a variable track pitch mode in the thirteenth embodiment.

FIG. 125 is an illustration of compressing magnetic recorded information by using a reference table of optical recorded information in the thirteenth embodiment.

FIG. 126 is a transversely sectional view of a head traverse portion in the thirteenth embodiment.

FIG. 127 is a flowchart of a recording and reproducing program in the thirteenth embodiment.

FIG. 128 is a flowchart of a recording and reproducing program in the thirteenth embodiment.

FIG. 129(a) is an illustration of a noise detecting head in the thirteenth embodiment.

FIG. 129(b) is an illustration of a noise detecting head in the thirteenth embodiment.

FIG. 129(c) is an illustration of a noise detecting head in the thirteenth embodiment.

FIG. 130 is an illustration of a magnetic sensor in the thirteenth embodiment.

FIG. 131 is a sectional view of a recording and reproducing apparatus according to a fourteenth embodiment of this invention.

FIGS. 132(a)-132(h) are a time-domain diagram of various signals in the fourteenth embodiment.

FIG. 133 is a perspective view of a cartridge for an optical recording medium in the fourteenth embodiment.

FIG. 134 is a block diagram of a recording and reproducing apparatus in the fourteenth embodiment.

FIGS. 135(a)-135(e) are a time-domain diagram of various signals in the fourteenth embodiment.

FIG. 136 is a block diagram of a recording and reproducing apparatus according to a fifteenth embodiment of this invention.

FIG. 137(a) is a perspective view of the fifteenth embodiment in which a cartridge is inserted into the apparatus.

FIG. 137(b) is a perspective view of the fifteenth embodiment in which the cartridge is fixed.

FIG. 137(c) is a perspective view of the fifteenth embodiment in which the cartridge is ejected from the apparatus.

FIG. 138(a) is a perspective view of the fifteenth embodiment in which a cartridge is inserted into the apparatus.

FIG. 138(b) is a perspective view of the fifteenth embodiment in which the cartridge is fixed.

FIG. 138(c) is a perspective view of the fifteenth embodiment in which the cartridge is ejected from the apparatus.

FIG. 139(a) is a sectional view of the fifteenth embodiment in which a cartridge is inserted into the apparatus.

FIG. 139(b) is a sectional view of the fifteenth embodiment in which the cartridge is fixed.

FIG. 139(c) is a sectional view of the fifteenth embodiment in which the cartridge is ejected from the apparatus.

FIG. 140 is a block diagram of a recording and reproducing apparatus according to a sixteenth embodiment of this invention.

FIG. 141(a) is a perspective view of the sixteenth embodiment in which a cartridge is inserted into the apparatus.

FIG. 141(b) is a perspective view of the sixteenth embodiment in which the cartridge is fixed.

FIG. 141(c) is a perspective view of the sixteenth embodiment in which the cartridge is ejected from the apparatus.

FIG. 142(a) is a perspective view of the sixteenth embodiment in which a cartridge is inserted into the apparatus.

FIG. 142(b) is a perspective view of the sixteenth embodiment in which the cartridge is fixed.

FIG. 142(c) is a perspective view of the sixteenth embodiment in which the cartridge is ejected from the apparatus.

FIG. 143(a) is a sectional view of the sixteenth embodiment in which a cartridge is inserted into the apparatus.

FIG. 143(b) is a sectional view of the sixteenth embodiment in which the cartridge is fixed.

FIG. 143(c) is a sectional view of the sixteenth embodiment in which the cartridge is ejected from the apparatus.

FIG. 144(a) is a diagram of a part of an apparatus for making a recording medium in the fourteenth embodiment.

FIG. 144(b) is a diagram of a part of an apparatus for making a recording medium in the fourteenth embodiment.

FIG. 145(a) is a top view of a recording medium in the fourteenth embodiment.

FIG. 145(b) is a top view of a recording medium in the fourteenth embodiment.

FIG. 145(c) is a top view of a recording medium in the fourteenth embodiment.

FIG. 146(a) is a sectional view of a recording medium in the fourteenth embodiment.

FIG. 146(a) is a sectional view of a recording medium in the fourteenth embodiment.

FIG. 147 is a block diagram of an apparatus according to a seventeenth embodiment of this invention.

FIG. 148 is a flowchart of a program in the seventeenth embodiment.

FIG. 149 is a block diagram of an apparatus according to an eighteenth embodiment of this invention.

FIG. 150 is a flowchart of a program in the eighteenth embodiment.

FIG. 151 is a block diagram of an apparatus according to a nineteenth embodiment of this invention.

FIG. 152 is a diagram of an optical address table and a magnetic address table in a recording medium in the nineteenth embodiment.

FIG. 153 is a block diagram of an apparatus in the nineteenth embodiment.

FIG. 154(a) is a diagram of an address table of an optical file and a magnetic file in the nineteenth embodiment.

FIG. 154(b) is a diagram of an address link table between two files in the nineteenth embodiment.

FIG. 155 is a sectional view of an optical recording medium in the nineteenth embodiment.

FIG. 156 is a flowchart of operation of starting up an optical disk in the nineteenth embodiment.

FIG. 157(a) is a flowchart of a program in a twentieth embodiment of this invention.

FIG. 157(b) is a diagram of an address data table of a magnetic file and an optical file in the twentieth embodiment.

FIG. 157(c) is a block diagram of a bug correcting portion in the twentieth embodiment.

FIG. 158(a) is a flowchart of a program in a twenty-first embodiment of this invention.

FIG. 158(b) is a diagram of a data correction table in the twenty-first embodiment.

FIG. 158(c) is a block diagram of a bug correcting portion in the twenty-first embodiment.

FIG. 159 is a block diagram of an apparatus according to a twenty-second embodiment of this invention.

FIG. 160 is a diagram of a file structure in a computer in the twenty-second embodiment.

FIG. 161 is a flowchart of a program in the twenty-second embodiment.

FIG. 162 is a flowchart of a program in the twenty-second embodiment.

FIG. 163 is a flowchart of a program in the twenty-second embodiment.

FIG. 164(a) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 164(b) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 164(c) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 164(d) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 165 is an illustration of a display screen of a computer in the twenty-second embodiment.

FIG. 166(a) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 166(b) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 166(c) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 166(d) is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 167(a) is an illustration of a display screen of a sub computer in the twenty-second embodiment.

FIG. 167(b) is an illustration of a display screen of a sub computer in the twenty-second embodiment.

FIG. 168 is a diagram of a network in the twenty-second embodiment.

FIG. 169 is an illustration of a display screen of a main computer in the twenty-second embodiment.

FIG. 170 is an illustration of a display screen of a computer in the seventeenth embodiment.

FIG. 171 is a diagram of a recording medium in the twenty-second embodiment.

FIG. 172(a) is a perspective view of a magnetic head in the thirteenth embodiment.

FIG. 172(b) is a sectional view of a magnetic head in the thirteenth embodiment.

FIG. 172(c) is a sectional view of a magnetic head in the thirteenth embodiment.

FIG. 173(a) is a perspective view of a magnetic head in the thirteenth embodiment.

FIG. 173(b) is a sectional view of a magnetic head in the thirteenth embodiment.

FIG. 174(a) is a perspective view of a magnetic head in the thirteenth embodiment.

FIG. 174(b) is a sectional view of a magnetic head in the thirteenth embodiment.

FIG. 175(a) is a perspective view of a magnetic head in the thirteenth embodiment.

FIG. 175(b) is a sectional view of a magnetic head in the thirteenth embodiment.

FIG. 176(a) is a perspective view of a noise detection coil in the thirteenth embodiment.

FIG. 176(b) is a sectional view of a noise detection coil in the thirteenth embodiment.

FIG. 177(a) is a perspective view of a noise detection coil in the thirteenth embodiment.

FIG. 177(b) is a block diagram of a noise detection system in the thirteenth embodiment.

FIG. 178(a) is a perspective view of a noise detection coil in the thirteenth embodiment.

FIG. 178(b) is a block diagram of a noise detection system in the thirteenth embodiment.

FIG. 179 is a diagram of frequency spectrums of reproduced signals which occur before and after noise cancel in the thirteenth embodiment.

FIG. 180 is a block diagram of a recording and reproducing apparatus in the twenty-second embodiment.

FIG. 181 is a block diagram of a recording and reproducing apparatus according to a twenty-third embodiment of this invention.

FIG. 182(a) is a top view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 182(b) is a top view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 183(a) is a sectional view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 183(b) is a sectional view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 183(c) is a sectional view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 183(d) is a sectional view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 183(e) is a sectional view of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 184(a) is a diagram of a data structure in a recording medium in the twenty-third embodiment.

FIG. 184(b) is a diagram of a data structure in a recording medium in the twenty-third embodiment.

FIG. 184(c) is a diagram of a data structure in a recording medium in the twenty-third embodiment.

FIG. 185(a) is a top view of a recording medium in the twenty-third embodiment.

FIG. 185(b) is a sectional view of a recording medium in the twenty-third embodiment.

FIG. 185(c) is a sectional view of a recording medium in the twenty-third embodiment.

FIG. 185(d) is a sectional view of a recording medium in the twenty-third embodiment.

FIG. 185(e) is a sectional view of a recording medium in the twenty-third embodiment.

FIG. 186(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 186(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 186(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 186(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 186(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 187(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 187(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 187(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 187(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 187(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 188(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 188(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 188(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 188(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 188(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 188(f) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 189(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 189(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 189(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 189(d) is a diagram of mathematical relations for calculating a track pitch in the twenty-third embodiment.

FIG. 190 is a block diagram of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 191(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 191(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 191(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 191(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 191(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 192(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 192(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 192(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 192(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 192(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 193(a) is a top view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 193(b) is a top view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 194(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 194(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 194(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 194(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 194(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIGS. 195(a) and 195(b) are a diagram of the relation between a distance from a magnetic head and the intensity of a dc magnetic field.

FIG. 196(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 196(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 196(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 197 is a top view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 198(a) is a sectional view of a magnetic head in the twenty-third embodiment.

FIG. 198(b) is a top view of a magnetic head in the twenty-third embodiment.

FIG. 198(c) is a sectional view of a magnetic head in the twenty-third embodiment.

FIG. 198(d) is a top view of a magnetic head in the twenty-third embodiment.

FIG. 199(a) is a top view of a recording medium in the twenty-third embodiment.

FIG. 199(b) is a top view of a recording medium in the twenty-third embodiment.

FIG. 199(c) is a sectional view of a recording medium in the twenty-third embodiment.

FIG. 200 is a block diagram of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 201(a) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 201(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 201(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 201(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 202 is a block diagram of a recording and reproducing apparatus in the first embodiment.

FIG. 203(a) is a diagram of the distribution of the frequencies of occurrence of periods T, 1.5 T, and 2 T in the first embodiment.

FIG. 203(b) is a diagram of the distribution of the frequencies of occurrence of periods T, 1.5 T, and 2 T in the first embodiment.

FIG. 204 is a diagram of the relation between the maximum burst correction length and the correction symbol number according to the CD standards.

FIG. 205 is a diagram of the dispersion length of data on a recording medium in the first embodiment.

FIG. 206 is a diagram of the relation between the data amount of an error correction code and the error rate in the first embodiment.

FIG. 207(a) is a diagram of arrangement conversion related to interleaving in the first embodiment.

FIG. 207(b) is a diagram of the data dispersion length related to interleaving in the first embodiment.

FIG. 208 is a block diagram of a de-interleaving portion in the first embodiment.

FIG. 209(a) is a block diagram of an ECC encoder in the first embodiment.

FIG. 209(b) is a block diagram of an ECC decoder in the first embodiment.

FIG. 210 is a flowchart of a program in the first embodiment.

FIG. 211 is a block diagram of a recording and reproducing apparatus in the first embodiment.

FIG. 212(a) is a diagram of arrangement conversion related to interleaving in the first embodiment.

FIG. 212(b) is a diagram of the data dispersion length related to interleaving in the first embodiment.

FIG. 213 is a diagram of the distance and the time interval of a CD subcode.

FIG. 214 is an illustration of a table of the correspondence between a magnetic track and an optical address in the fourteenth embodiment.

FIG. 215 is a block diagram of a subcode sync signal detector and a magnetic recording portion in the fourteenth embodiment.

FIG. 216 is a block diagram of a recording and reproducing apparatus in the fourteenth embodiment.

FIG. 217 is a block diagram of a recording and reproducing apparatus in the fourteenth embodiment.

FIG. 218(a) is a time-domain diagram of an optical reproduction sync signal in the fourteenth embodiment.

FIG. 218(b) is a time-domain diagram of the conditions of magnetic recording operation in the fourteenth embodiment.

FIG. 218(c) is a time-domain diagram of a magnetic record sync signal in the fourteenth embodiment.

FIG. 218(d) is a time-domain diagram of the conditions of optical reproducing operation in the fourteenth embodiment.

FIG. 218(e) is a time-domain diagram of an optical reproduction sync signal in the fourteenth embodiment.

FIG. 218(f) is a time-domain diagram of the conditions of magnetic reproducing operation in the fourteenth embodiment.

FIG. 218(g) is a time-domain diagram of a magnetic reproduction sync signal in the fourteenth embodiment.

FIG. 218(h) is a time-domain diagram of magnetic reproduced data in the fourteenth embodiment.

FIG. 219 is a diagram of a disk eccentricity according to the CD standards.

FIG. 220 is a diagram of a file structure in the twenty-second embodiment.

FIG. 221 is a flowchart of a program in the thirteenth embodiment.

FIG. 222(a) is a top view of a recording medium in a cartridge in the twenty-third embodiment.

FIG. 222(b) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 222(c) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 222(d) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 222(e) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 222(f) is a sectional view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 223(a) is a sectional view of a recording medium in the twelfth embodiment.

FIG. 223(b) is a diagram of the physical structure of a medium identifier in the twelfth embodiment.

FIG. 223(c) is an exploded view of FIG. 223(a)

FIG. 224 is a diagram of a file structure in the twenty-second embodiment.

FIG. 225 is a diagram of a file structure in the twenty-second embodiment.

FIG. 226 is a perspective view of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 227 is a block diagram of a recording and reproducing apparatus in the twenty-third embodiment.

FIG. 228 is a diagram of a data structure of a video CD for the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 229 is a flowchart of operation of the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 230 is a diagram of a selection number table and a menu picture number in the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 231(a) is a diagram of a data format of a prior art video CD.

FIG. 231(b) is a diagram of a data format of a prior art video CD.

FIG. 232 is a diagram of optical address search information in the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 233 is a diagram of a data structure in the recording and reproducing apparatus in the twenty-third embodiment.

FIG. 234 is a block diagram of a mastering apparatus in the seventeenth embodiment.

FIG. 235(a) is a time-domain diagram of a linear velocity which occurs during a recording process in the seventeenth embodiment.

FIG. 235(b) is a diagram of an address position on an optical disk which occurs at a linear velocity of 1.2 m/s in the seventeenth embodiment.

FIG. 235(c) is a diagram of an address position on an optical disk which occurs upon a change of a linear velocity from 1.2 m/s to 1.4 m/s in the seventeenth embodiment.

FIG. 236(a) is a diagram of a physical arrangement (layout) of addresses in a legal (legitimate) CD in the seventeenth embodiment.

FIG. 236(b) is a diagram of a physical arrangement (layout) of addresses in an illegally copied CD in the seventeenth embodiment.

FIG. 237(a) is a time-domain diagram of a disk rotation pulse in the seventeenth embodiment.

FIG. 237(b) is a time-domain diagram of a physical position signal in the seventeenth embodiment.

FIG. 237(c) is a time-domain diagram of address information in the seventeenth embodiment.

FIG. 238 is a diagram of copy protection for a CD in the seventeenth embodiment.

FIG. 239 is a block diagram of a recording and reproducing apparatus in the seventeenth embodiment.

FIG. 240 is a flowchart of a check on an illegally copied disk in the seventeenth embodiment.

FIG. 241(a) is a diagram of steps for making a CD into which an ID number is recorded.

FIG. 241(b) is a diagram of steps for making a prior art CD.

FIG. 242(a) is a top view of a magnetizing apparatus in the seventeenth embodiment.

FIG. 242(b) is a side view of the magnetizing apparatus in the seventeenth embodiment.

FIG. 242(c) is an enlarged side view of the magnetizing apparatus in the seventeenth embodiment.

FIG. 242(d) is a block diagram of the magnetizing apparatus in the seventeenth embodiment.

FIG. 243 is a diagram of inputting of an ID number in the seventeenth embodiment.

FIG. 244(a) is a time-domain diagram of a constant linear velocity in the seventeenth embodiment.

FIG. 244(b) is a time-domain diagram of a varying linear velocity in the seventeenth embodiment.

FIG. 244(c) is a diagram of a physical arrangement (layout) of addresses which occur at a constant linear velocity in the seventeenth embodiment.

FIG. 244(d) is a diagram of a physical arrangement (layout) of addresses which occur upon a change in a linear velocity in the seventeenth embodiment.

FIG. 245(a) is a sectional view of a legal (legitimate) original disk in the seventeenth embodiment.

FIG. 245(b) is a sectional view of a legal (legitimate) molded disk in the seventeenth embodiment.

FIG. 245(c) is a sectional view of an illegally copied original disk in the seventeenth embodiment.

FIG. 245(d) is a sectional view of an illegally copied molded disk in the seventeenth embodiment.

FIG. 246 is a block diagram of a CD making apparatus and a recording and reproducing apparatus in the seventeenth embodiment.

FIG. 247 is a flowchart of operation in the seventeenth embodiment.

FIG. 248 is a diagram of an arrangement (layout) of addresses in an original disk in the seventeenth embodiment.

FIG. 249 is a block diagram of a recording and reproducing apparatus in the seventeenth embodiment.

FIG. 250(a) is a sectional view of an illegal disk in the seventeenth embodiment.

FIG. 250(b) is a sectional view of a legal (legitimate) disk in the seventeenth embodiment.

FIG. 250(c) is a diagram of a waveform of an optical reproduced signal in the seventeenth embodiment.

FIG. 250(d) is a diagram of a waveform of a digital signal in the seventeenth embodiment.

FIG. 250(e) is a diagram of an envelope in the seventeenth embodiment.

FIG. 250(f) is a diagram of a waveform of a digital signal in the seventeenth embodiment.

FIG. 250(g) is a diagram of a waveform of a detection signal in the seventeenth embodiment.

FIG. 251 is a diagram of a disk physical arrangement (layout) table in the seventeenth embodiment.

FIG. 252(a) is a diagram of an address arrangement (layout) in an optical disk fee from an eccentricity in the seventeenth embodiment.

FIG. 252(b) is a diagram of an address arrangement (layout) in an optical disk with an eccentricity in the seventeenth embodiment.

FIG. 253(a) is a diagram of a tracking variation amount in a legal (legitimate) disk in the seventeenth embodiment.

FIG. 253(b) is a diagram of a tracking variation amount in an illegally copied disk in the seventeenth embodiment.

FIG. 254(a) is a diagram of an address An in the seventeenth embodiment.

FIG. 254(b) is a diagram of an angle Zn in the seventeenth embodiment.

FIG. 254(c) is a diagram of a tracking amount Tn in the seventeenth embodiment.

FIG. 254(d) is a diagram of a pit depth Dn in the seventeenth embodiment.

FIGS. 255(a)-255(h) are a time-domain diagram of an laser output, a pit depth, and a reproduced signal in the seventeenth embodiment.

FIG. 256 is a diagram of copy protection effects with respect to original disk making apparatuses in the seventeenth embodiment.

FIG. 257 is a block diagram of an original disk making apparatus in the seventeenth embodiment.

FIG. 258 is a block diagram of an original disk making apparatus in the seventeenth embodiment.

FIG. 259 is a block diagram of an original disk making apparatus in the seventeenth embodiment.

FIG. 260 is a block diagram of an original disk making apparatus in the seventeenth embodiment.

FIG. 261 is a block diagram of an original disk making apparatus in the seventeenth embodiment.

FIG. 262 is a block diagram of an original disk making system in the seventeenth embodiment.

FIG. 263(a) is a diagram of a waveform of a laser output in the seventeenth embodiment.

FIG. 263(b) is a diagram of a waveform of a laser output in the seventeenth embodiment.

FIG. 263(c) is a sectional view of a disk substrate in the seventeenth embodiment.

FIG. 263(d) is a sectional view of a disk substrate in the seventeenth embodiment.

FIG. 263(e) is a sectional view of a molded disk in the seventeenth embodiment.

FIGS. 264(a)-264(h) are a diagram of the relation between a laser record output and a reproduced signal in the seventeenth embodiment.

FIGS. 265(a)-265(j) are a diagram of steps of making an original disk in the seventeenth embodiment.

FIG. 266(a) is a top view of an original disk in the seventeenth embodiment.

FIG. 266(b) is a sectional view of a press of an original disk in the seventeenth embodiment.

FIGS. 267(a)-(i) are a diagram of steps of making an original disk in the seventeenth embodiment.

FIG. 268(a) is a top view of an original disk in the seventeenth embodiment.

FIG. 268(b) is a sectional view of a press of an original disk in the seventeenth embodiment.

FIG. 269 is a flowchart of operation in the seventeenth embodiment.

FIG. 270 is a flowchart of an application software in the seventeenth embodiment.

FIG. 271 is a diagram of display operation in the twenty-second embodiment.

FIG. 272 is a diagram of display operation in the twenty-second embodiment.

FIG. 273 is a diagram of display operation in the twenty-second embodiment.

FIG. 274 is a flowchart of a program for indicating a virtual file in a window in the twenty-second embodiment.

DESCRIPTION OF THE FIRST PREFERRED EMBODIMENT

With reference to FIG. 1, a recording and reproducing apparatus 1 contains a recording medium 2 which includes a laminated structure of a magnetic recording layer 3, an optical recording layer 4, and a transparent layer 5.

During the magneto-optical reproduction, light emitted from a light emitting section is focused on the optical recording layer 4 by an optical head 6 and an optical recording block 7, and a magneto-optically recorded signal is reproduced from the recording medium 2.

During the magneto-optical recording, laser light is focused on a given region of the optical recording layer 4 by the optical head 6 and the optical recording block 7 so that a temperature at the given region increases to or above a Curie temperature of the optical recording layer 4. Under these conditions, a magnetic field applied to the given region of the optical recording layer 4 is modulated by a magnetic head 8 and a magnetic recording block 9 in response to information to be recorded, so that recording of the information on the optical recording layer 4 is done.

During the magnetic recording, the magnetic head 8 and the magnetic recording block 9 are used in recording information on the magnetic recording layer 3.

A system controller 10 receives operating information and output information from various circuits, and drives a drive block 11 and executes control of a motor 17 and tracking and focusing control with respect to the optical head 6. The system controller 10 includes a microcomputer or a similar device having a combination of a CPU, a ROM, a RAM, and an I/O port. The system controller 10 operates in accordance with a program stored in the ROM.

In the case where an input signal fed from an exterior is required to be recorded, a recording instruction is fed to the system controller 10 from an interface 14 or a keyboard 15 in response to the reception of the input signal or the operation of the keyboard 15 by the user. The system controller 10 outputs an inputting instruction to an input section 12, and also outputs an optical recording instruction to the optical recording block 7. The input signal, for example, an audio signal or a video signal, is received by the input section 12 and is converted by the input section 12 into a digital signal of a given format such as a PCM format. The digital signal is fed from the input section 12 to an input section 32 of the optical recording block 7, being coded by an ECC encoder 35 for error correction. An output signal of the ECC encoder 35 is transmitted to the magnetic head 8 via an optical recording circuit 37, and a magnetic recording circuit 29 and a magnetic recording circuit 29 in the magnetic recording block 9. The magnetic head 8 generates a recording magnetic field responsive to an optical recording signal, and applies the magnetic field to magneto-optical material (photo-magnetic material) in a given region of the optical recording layer 4. Recording material in a narrower region of the optical recording layer 4 is heated to a Curie temperature or higher by laser light applied from the optical head 6, so that this region of the optical recording layer 4 undergoes a magnetization change or transition responsive to the applied magnetic field. Thus, as shown in FIG. 2, narrower regions of the optical recording layer 4 are sequentially magnetized as denoted by arrows 52 while the recording medium 2 is rotated and scanned in a direction 51.

During the previously-mentioned recording of information on the optical recording layer 4, the system controller 10 receives tracking information, address information, and clock information from an optical head circuit 39 and an optical reproducing circuit 38 which have been recorded on the optical recording layer 4, and the system controller 10 outputs control information to the drive block 11 on the basis of the received information. Specifically, the system controller 10 feeds a control signal to a motor drive circuit 26 to control the rotational speed of the motor 17 for driving the recording medium 2 so that a relative speed between the optical head 6 and the recording medium 2 will be equal to a given linear velocity.

An optical head drive circuit 25 and an optical head actuator 18 execute tracking control responsive to a control signal from the system controller 10 so that a light beam will scan a target track on the recording medium 2. In addition, the optical head drive circuit 25 and the optical head actuator 18 execute focusing control responsive to a control signal from the system controller 10 so that the light beam will be accurately focused on the optical recording layer 4.

In the case where the access to another track is required, a head moving circuit 24 and a head moving actuator 23 move a head base 19 in response to a control signal from the system controller 10 so that the optical head 6 and the magnetic head 8 on the head base 19 will be moved together. Thus, the both heads reach equal radial positions on opposite surfaces of the recording medium 2 which align with a desired track.

A head elevator 20 for the magnetic head 8 is driven by a magnetic head elevating circuit 22 and an elevating motor 21 in response to a control signal from the system controller 10. During a time where a disk cassette 42 is being loaded with the recording medium 2 or where magnetic recording is not executed, the magnetic head 8 and a slider 41 are separated from the magnetic recording layer 3 of the recording medium 2 to prevent wear of the magnetic head 8.

As described previously, the system controller 10 feeds various control signals to the drive block 11, and thereby executes tracking control and focusing control of the optical head 6 and the magnetic head 8, elevation control of the magnetic head 8, and control of the rotational speed of the motor 17.

A description will now be given of a method of reproducing a magneto-optically recorded signal. As shown in FIG. 2, laser light emitted from the light emitting section 57 is incident to a polarization beam splitter 55, being reflected and directed toward an optical path 59 by the polarization beam splitter 55. The laser light travels along the optical path 59, being incident to a lens 54 and then being focused on the optical recording layer 4 of the recording medium 2 by the lens 54. In this case, focusing and tracking control is done by driving only the lens 54 through the optical head drive section 18.

As shown in FIG. 2, the magneto-optical material of the optical recording layer 4 is in magnetized conditions depending on the optical recorded signal. Thus, the polarization angle of reflected light traveling back along an optical path 59a depends on the direction of the magnetization of the optical recording layer 4 due to the Kerr effect. The reflected light is separated from the forward light by the polarization beam splitter 55, traveling through the polarization beam splitter 55 and entering another polarization beam splitter 56. The reflected light is divided by the polarization beam splitter 56 into two beams incident to light receiving sections 58 and 58a respectively. The light receiving sections 58 and 58a convert the incident light beams into corresponding electric signals respectively. A subtractor (not shown) derives a difference between the output signals of the light receiving sections 58 and 58a. Since the derived difference depends on the direction of the magnetization of the optical recording layer 4, the subtractor generates a signal equal to the reproduction of the optical recorded signal. In this way, the optical recorded signal is reproduced.

The reproduced signal is fed from the optical head 6 to the optical recording block 7, being processed by the optical head circuit 39 and the optical reproducing 38 and being subjected to error correction by an ECC decoder 36. As a result, the original digital signal is recovered from the reproduced signal. The recovered original digital signal is fed to an output section 33. The output section 33 is provided with a memory which stores a quantity of the recorded signal (the recorded information) which corresponds to a given interval of time. In the case where the memory 34 consists of a 1-Mbit IC memory and a compressed audio signal having a bit rate of 250 kbps is handled, a quantity of the recorded signal which corresponds to a time of about 4 seconds can be stored. In the case of an audio player, if the optical head 6 moves out of tracking by an external vibration, the recovery of tracking in a time of 4 seconds prevents the occurrence of a discontinuity in a reproduced audio signal. The reproduced signal is then transmitted from the output section 33 to an output section 13 at a final stage. In the case where the reproduced signal represents audio information, the reproduced signal is subjected to PCM demodulation before being outputted to an external device as an analog audio signal.

A description will now be given of a magnetic recording mode of operation. In FIG. 1, an input signal applied to an input section 12 from an external device or an output signal of the system controller is transmitted to an input section 21A of the magnetic recording block 9, being subjected by the ECC encoder 35 in the optical recording block 7 to a coding process such as an error correcting process. The resultant coded signal is transmitted to the magnetic head 8 via the magnetic recording circuit 29 and the magnetic head circuit 31.

With reference to FIG. 3, the magnetic recorded signal fed to the magnetic head 8 is converted by a winding 40 into a corresponding magnetic field. The magnetic material of the magnetic recording layer 3 is vertically magnetized by the magnetic field as denoted by arrows 61 in FIG. 3. In this way, magnetic recording in a vertical direction is done so that the information signal is recorded on the recording medium 2. The recording medium 2 has a vertically magnetized film. As the recording medium 2 is moved along a direction 51, time segments of the information signal is sequentially recorded on the magnetic recording medium 2. In this case, although the optical recording layer 4 is also subjected to the magnetic field, the optical recording layer 4 is prevented from being magnetized by the magnetic field since the magneto-optical material of the optical recording layer 4 has a magnetic coercive force of several thousands to ten thousands of Oe at temperatures below the Curie temperature.

In the case where a portion of the magnetic recording layer 3 which actually undergoes the magnetic recording process is excessively close to the optical recording layer 4, the intensity of a magnetic filed applied to the optical recording layer 4 from the magnetic recording portion of the magnetic recording layer 3 sometimes reaches a level of several tens to several hundreds of Oe. Under these conditions, in the case where the temperature of the optical recording layer 4 is increased above the Curie temperature for magneto-optical recording, the optical recording layer 4 tends to undergo a magnetization change or transition in response to the magnetic field from the magnetic recording portion of the magnetic recording layer 3 so that an error rate increases during the magneto-optical recording. To resolve such a problem, it is preferable to provide an interference layer 81 of a given thickness between the magnetic recording layer 3 and the optical recording layer 4 as shown in FIG. 7. Opposite surfaces of the optical recording layer 4 are provided with protective layers 82 and 82a to prevent deterioration thereof. The sum of the thickness of the interference layer 81 and the thickness of the protective layer 82 is equal to an interference interval or distance L. In this case, an attenuation rate is given as 56.4.times.L/.lambda. where .lambda. denotes a magnetic recording wavelength. When .lambda.=0.5 .mu.m, an interference interval L of 0.2 .mu.m or greater can provide an adequate level of the effect.

As shown in FIG. 8, a protective layer 82 of a thickness equal to or greater than the interference interval may be provided between the magnetic recording layer 3 and the optical recording layer 4.

The magnetic recording medium 2 of FIG. 7 was fabricated as follows. The protective layer 82 and the interference layer 81 were sequentially formed on the optical recording layer 4. Magnetic material such as barium ferrite was prepared which had vertical anisotropy. Lubricant, binder, and the magnetic material were mixed. The resultant mixture was applied to the substrate by spin coat to form the magnetic recording layer 3 while a magnetic field was applied to the substrate in the vertical direction of the substrate.

The recording and reproducing apparatus 1 can operate on a ROM disk similar to a compact disk (CD). FIG. 9 shows an example of a ROM-type recording medium 2. The recording medium 2 of FIG. 9 was fabricated as follows. A substrate 5 was provided with pits. A reflecting film 84 of suitable material such as aluminum was formed over the pits of the substrate 5. Lubricant, binder, and magnetic material were mixed. The resultant mixture was applied to the reflecting film 84 to form a magnetic recording layer 3 while a magnetic field was applied to the substrate 5 in the vertical direction of the substrate 5. The magnetic recording layer 3 had a vertical magnetic recording film. The recording medium of FIG. 9 has the function of a CD ROM at one side, and has the function of a RAM at the other side. Thus, the recording medium of FIG. 9 provides various advantages as described later. In this case, a cost increase results from only adding the magnetic substance to the material which will form a protective film through spin coat similar to that executed to fabricate a currently-used CD. Accordingly, a manufacturing cost increase corresponds to only the cost of the magnetic substance. Since the cost of the magnetic substance is equal to a few percent of the manufacturing cost of the recording medium, the cost increase is very small.

During the magnetic recording, tracking is executed as follows. In FIG. 1, the optical head 6 and the optical head circuit 39 reproduce tracking information from the recording medium 2. The system controller 10 outputs a moving instruction to the head moving circuit 24 in response to the reproduced tracking information, driving the actuator 23 and thereby moving the head base 19 in the tracking direction. Thus, as shown in FIG. 4, light beam fitted from the optical head 6 is focused into a spot 66 near a given optical recording track 65 of the optical recording layer 4. The optical head drive section 18 for driving the optical head 6 is mechanically couped with the magnetic head 8 via the head base 19 and the head elevator 20. Therefore, the magnetic head 8 moves in the tracking direction as the optical head 6 moves. Thus, when the optical head 6 is aligned with the given optical track 66, the magnetic head 8 is moved into alignment with a given magnetic track 67 which extends at the opposite side of the optical track 66. Guard bands 68 and 68a are provided at opposite sides of the magnetic track 67. As shown in FIG. 5, when the position of the optical head 6 is controlled so as to scan a given Tn-th optical track 65, the magnetic head 8 runs along a given Mm-th magnetic track 67 extending at the opposite side of the optical track 65. In this case, the drive system for the optical head 6 suffices and it is unnecessary to provide a tracking control device for the magnetic head 8. Furthermore, it is unnecessary to provide a linear sensor required in a conventional magnetic disk drive.

A description will now be given of a method of accessing an optical track and a magnetic track. The optical head 6 is subjected to tracking together with the magnetic head 8. Therefore, in the case where there is a difference in radial direction between an optical track currently exposed to an information recording or reproducing process from the lower surface and a magnetic track desired to be accessed from the upper surface, the two tracks can not be accessed at the same time. In the case of a data signal, this access problem causes only a delay in access and does not cause a significant problem. In the case of a continuous signal such as an audio signal or a video signal, an interruption is generally unacceptable. Thus, the magnetic recording can not be executed during an optical recording or reproducing process at a normal speed. This embodiment uses the system in which the memory 34 is provided in connection with the input section 32 and the output section 33 to store a quantity of a signal which corresponds to an interval equal to several times the maximum access time of magnetic recording.

As shown in FIG. 6, the rotational speed of the recording medium 2 is increased by n times during a recording or reproducing process, and thereby an optical recording or reproducing time T is shortened to 1/n as compared with that of a normal speed and becomes equal to T1 and T2. Thus, a time T0 between t2 and t5 which equals to n-1 times the recording or reproducing time is a margin time. In the case where a magnetic track is accessed during an access time Ta between t2 and t3 in the margin time T0 and a magnetic recording or reproducing process is done during a recording or reproducing time TR between t3 and t4 and where head return or motion to an original optical track or a next optical track is done during a return time Tb between t5 and t6, access for the optical recording and access for the magnetic recording can be executed in time division by a single head moving section. In this case, the capacity of the memory 34 is chosen so that the memory 34 can store a continuous signal during the margin time T0.

Access to a track by the magnetic head 8 will now be described with reference to FIG. 6 and FIGS. 10-16. A cassette 42 shown in FIG. 15 includes the recording medium 2. The cassette 42 is inserted into a recess in a casing of the recording and reproducing apparatus 1 shown in FIG. 16. Then, as shown in FIG. 10, a light beam emitted from the optical head 6 is focused on an optical track 65 in a TOC region on a recording surface of the recording medium 2, and TOC information is reproduced. Index information is recorded in the TOC region. During the reproduction of the TOC information, the magnetic head 8 travels on a magnetic track 67 at the opposite side of the optical track 65 so that magnetically recorded information is reproduced from the magnetic track 67. In this way, during the first process, information is reproduced from the optical track in the TOC region of the recording medium 2, and simultaneously information is reproduced from the magnetic track. The information reproduced from the magnetic track represents the contents of previous access, conditions at the end of previous operation, or others. As shown in FIG. 16, the contents of the reproduced information are indicated on a display 16.

In the case of audio information, a final music number, an elapsed time of an interruption thereof, a reserved music number, or others are automatically recorded on the magnetic recording region. When the magnetic recording medium 2 is inserted into the recording and reproducing apparatus 1 again, information of a table of contents is reproduced from the optical track 65 and also information at the end of previous operation is reproduced from the magnetic track 67 as previously described. The reproduced information is indicated on the display 16 as shown in FIG. 16. FIG. 16 shows conditions where the previous access end time, the operator name, the final music number, the elapsed time of an interruption, the previously preset music order, and the music number are recorded and indicated. Specifically, "Continue?" is indicated. When "Yes" is inputted as a reply, the music starts to be reproduced from a point at which the previous operation ends. When "No" is inputted as a reply, the music is reproduced in the preset order. In this way, the user is enabled to enjoy the automatic reproduction of the previously-interrupted contents as they are, or to listen the music in the desired order.

In the case of a CD ROM game device 18 shown in FIG. 18, the previously interrupted game contents, for example, the stage number, the acquired points, and the item attainment number, are recorded and reproduced. Upon the start of the game a certain time after the previous end of the game, the game can be started from the place same as the previous place and the conditions same as the previous conditions. This advantage can not be provided by a prior art CD ROM game device.

The above-mentioned simple method of accessing the magnetic track in the TOC region has an advantage in that the structure is simple and the cost is low although the memory capacity is small.

A description will now be given of access to a track outside the TOC region. FIG. 11 shows conditions where the optical head 6 accesses a given optical track 65a. At this time, the magnetic head 8 which moves together with the optical head 6 accesses a magnetic track 67a at the opposite side of the optical track 65a. In the case where required information is on a magnetic track 67b separate from the magnetic track 67a, it is necessary to move the magnetic head 8 to the magnetic track 67b. In this case, as previously described with reference to FIG. 6, it is necessary to complete the head movement, the recording, and the head return in a margin time T0. List information representing the correspondence between the magnetic track numbers and the optical track numbers is previously recorded on a TOC region or another given region of the optical recording layer 4. The list information is read out, and the optical track number corresponding to the required magnetic track number is calculated by referring to the list information. Then, as shown in FIG. 12, during an access time Ta, the head base 19 is moved and fixed so that the optical head 6 can access an optical track 65b corresponding to the calculated optical track number. Thus, the magnetic head 8 will follow the required magnetic track 67b. In this way, the magnetic recording or reproduction can be executed. In this case, as shown in FIG. 13, while the optical track 65a is being scanned, the magnetic head 8 remains lifted to an upper position well separated from the magnetic recording layer 3 by the elevating motor 21. In addition, during the access time Ta, as denoted by the character ".omega." in FIG. 6, the rotational speed of the motor 17 is lowered. While the rotational speed remains low, the magnetic head 8 is moved downward into contact with the magnetic recording layer 3. Thereby, it is possible to prevent the magnetic head 8 from being damaged. During an interval TR, the rotational speed is increased and the magnetic recording is done. During an interval Tb, the rotational speed is lowered and the magnetic head 8 is lifted. Then, the rotational speed is increased again, and the optical head 6 is returned to the optical track 65a as shown in FIG. 13. During an interval T2, optical recording and reproduction is done. Since the data stored in the memory 34 is reproduced during the margin time T0, the reproduced signal or the reproduced music will not be interrupted. As shown in FIG. 14, during access to the TOC region, the magnetic head 8 is not moved downward in the presence of an instruction representing that magnetic recording on the TOC region is unnecessary. Thereby, even if a recording medium 2 having no magnetic recording layer 3 is inserted into the recording and reproducing apparatus, the magnetic head 8 can be prevented from contacting the recording medium 2 and being thus damaged. In this way, the execution of the upward and downward movement of the magnetic head 8 during a period of the occurrence of a lowered rotational speed provides an advantage such that a damage to the magnetic head 8 can be prevented and wear thereof can be remarkably reduced.

FIG. 15 shows the cassette 42 which contains the recording medium 2. The cassette 42 is provided with a shutter 88, a magnetic recording prevention click 89, and an optical recording prevention click 89a. The magnetic recording prevention and the optical recording prevention can be set separately. In the case of a ROM cassette, only a magnetic recording prevention click 89a is provided thereon.

FIG. 17 shows a recording and reproducing apparatus for reproduction of optically recorded information. An optical recording circuit and an ECC encoder are omitted from an optical recording block 7 in the recording and reproducing apparatus of FIG. 17 as compared with that of FIG. 1. The recording and reproducing apparatus of FIG. 17 additionally includes a magnetic head elevator 20, a magnetic head 8, and a magnetic recording block 9 as compared with a conventional reproduction player such as a CD player. All the parts of the recording and reproducing apparatus of FIG. 17 can be used in common to the parts of the recording and reproducing apparatus of FIG. 1. Their costs are very low relative to optical recording parts, and the resultant cost increase is small. Although the memory capacity is smaller than that of a floppy disk, information can be recorded and reproduced on and from a ROM-type recording medium at such a low cost. Thus, in the case of a game device or a CD player requiring only a small memory capacity, various advantages are provided as previously described. According to estimation, in the case of a recording medium disk having a diameter of 60 mm, a magnetic recording memory capacity of about 1 KB to 10 KB is obtained by using a magnetic head for modulating a magnetic field. A memory of a 2-KB or 8-KB SRAM is provided on a typical game ROM IC, and thus the above-mentioned memory capacity is sufficient. Thus, there is an advantage such that the recording medium disk can replace a ROM IC.

The error correction encoder 35 and the error correction decoder 36 of FIG. 1 will now be described in detail. With respect to a normal magnetic disk such as a 3.5-inch floppy disk of the 2 HD type or the 2 DD type, an error correcting process is not executed. In the case of the 3.5-inch 2 HD floppy disk, the error rate is close to 10-12 when record and reproduction are done at 135 TPI. Accordingly, in the case where this floppy disk is used in a cartridge, the disk is less contaminated or injured so that there hardly occurs a burst error. Therefore, it is unnecessary to execute error correction including interleaving. A CD ROM having a magnetic recording layer on a medium front surface or back surface is used without any cartridge. In the case of such a CD ROM, dust and a scratch cause a burst error.

The recording medium of this invention is designed so that Hc=1900 Oe. The magnetic recording layer is applied to the CD label side in which the space loss by the print layer and the protective layer is 9 to 10 micrometers. During experiments, his recording medium was subjected 10.sup.6 times to recording and reproducing processes by a magnetic head of the amorphous lamination (multilayer) type through MFM modulation at 500 BPI, that is, a wavelength of 50 .mu.m, and the frequencies of appearance of respective pulse widths were measured. FIGS. 203(a) and FIG. 203(b) show the results of the measurement. FIG. 203(a) shows the results of the measurement of the pulse with up to 1 ms. FIG. 203(b) shows the enlarged measurement data of the pulse width up to 100 .mu.s.

As denoted by the arrow 51a of FIG. 203(a), some burst errors having long periods occur with respect to sampling of 10.sup.6 times. Thus, interleaving is done as shown in the error correcting portion 35 of FIG. 1 or FIG. 202. Specifically, as shown in FIGS. 207(a) and 207(b), ECC encoding is done before or after the interleaving.

As shown in FIG. 203(b), the intervals of 1 T, 1.5 T, and 2 T in MFM modulation are adequately large. Thus, it is thought that an error rate of about 10.sup.-5 to 10.sup.-6 occurs under bad conditions.

Burst errors more frequently occur in comparison with a disk in a cartridge such as a floppy disk. In addition, more random error occur by several orders. Accordingly, to use such a recording medium without any cartridge, interleaving and good correction are necessary. As the amount of error correction code increases, the degree of redundancy increases but the amount of data decreases. A target value of burst error countermeasure is determined with reference to the allowable standard (reference) of scratch of a CD. The probability of the occurrence of a scratch on the optical recording surface is equal to that on the label surface. FIG. 204 shows the ability of error correction with respect to a scratch on the optical recording layer of a CD. In the case of correction of 4 symbols, it is possible to compensate for a scratch corresponding to 14 frames or less, that is, a scratch having a length of 2.38 mm or less. The interleaving length is set to correspond to 108 frames, that is, a length of 18.36 mm. Thus, with respect to the magnetic recording layer, it is necessary to provide error correcting ability containing interleaving which can compensate for a scratch having a length of 2.38 mm or less. In this case, an optimal degree of redundancy is attained. Therefore, even if the magnetic recording portion of this recording medium is subjected to such a scratch, the resultant errors are corrected by the encoder 35 and the decoder 36 so that data errors do not occur. Thus, the user can handle the recording medium of this invention similarly to a CD or a CD ROM.

According to this invention, it was experimentally confirmed that a scratch of 7 mm at an outermost portion and a scratch of 3 mm at an innermost portion were compensated under conditions where the interleaving corresponded to a length of 18 mm or more and Reed-Solomon error correction was used, and the degree of redundancy corresponded to a factor of 1.2 in the range of upper and lower 10% as shown in FIG. 206. Thus, a scratch of 2.38 mm could be compensated under these conditions. The interleaving length Ld on the data is defined as shown in FIG. 205, and a physical interleaving length LM on the medium surface is set to 18 mm or more. In addition, as shown in FIG. 206, the data amount of error correction code such as Reed-Solomon code is set equal to the original data amount multiplied by a value of 0.08 to 0.32. Thereby, it is possible to attain error correction against a scratch which is comparable with that in a CD.

FIG. 202 shows the details of the error correction encoder 35 and the error correction decoder 36. The magnetic record signal is ECC-encoded by a Reed-Solomon encoder 35a for executing an operation of Reed-Solomon encoding. A transverse-direction parity 452a is added to the ECC-encoded data sequence. In an interleaving portion 35b, according to an interleaving table of FIGS. 207(a) and 207(b), the data sequence is read out in a longitudinal direction 51b so that the original data is separated by a dispersion distance L on the recording medium surface as shown in FIG. 207(b). Even in the presence of a burst error, the data can be recovered in response to the parity 452. When the dispersion length L is set to 19 mm or more, an error compensating ability comparable to that of a CD can be attained. With respect to the reproduced signal, in a de-interleaving portion 36b shown in FIG. 208, the data is mapped onto a RAM 36x and is then subjected to address conversion reverse to that of FIGS. 207(a) and 207(b) so that the data is returned to the original arrangement (sequence).

Then, the reproduced data is processed by, a Reed-Solomon decoder 36a of FIG. 209(b) as follows. As shown in FIG. 210, at a step 452b, P and Q parities and the data are inputted. At a step 452c, syndromes S1 and S2 are calculated. Only when S1=S2=0 at a step 452d, an advance to a step 452g is done so that the data is outputted. In the presence of an error, calculation for error correction is executed at a step 452e. Only when the error is corrected by a step 452f, the data is outputted at the step 452g. In this invention, the demodulation clock speed (rate) in the magnetic recording and reproducing portion is equal to 30 Kbps (see FIGS. 203(a) and 203(b)) which is a data rate equal to 1/100 of the CD data rate. In view of this small data processing amount, error correction of the optical reproduced signal is done by an exclusive IC while the signal processing in the error correction encoder 35 and the error correction decoder 36 of FIG. 202 is executed by a microcomputer 10a in the system controller 10 through a time division technique. Specifically, the interleaving of FIGS. 207(a) and 207(b) and the error correction in FIG. 210 are done by the microcomputer 10a.

The microcomputer 10a is of the 8-bit or 16-bit type driven by a clock signal having a several tens of MHz. As shown in FIG. 210, two routines, that is, a system control routine 452p and an error correcting routine 452a are executed in time division. Specifically, the system control routine is started as a step 452h, and motor rotation control is executed at a step 452j. At a step 452k, control for head movement and control for an actuator such as a traverse are executed. At a step 452m, indication of a drive and control of an input/output drive system are executed. Only in the case where one work unit for the system control is completed at a step 452n and error correction is required, entrance into the error correction routine 452q is done. At a step 452r, interleaving or de-interleaving is executed which has been described with reference to FIGS. 207(a) and 207(b). Steps 452b-452g execute calculations for the previously-mentioned error correction.

In this invention, the magnetic recording has a data rate of about 30 kbps. Accordingly, an 8-bit or 16-bit microcomputer chip driven by a clock signal having a frequency of about 10 MHz can be used in executing the system control and the error correction. In the case where the error correction related to the optical reproduction is executed by an exclusive IC and the error correction related to the magnetic recording and reproduction is executed by the microcomputer, it is possible to omit a magnetic error correction circuit. Since it is unnecessary to add a new error correction circuit with an interleaving function in this way, this design is advantageous in that the structure of the apparatus is simple.

FIG. 211 shows an arrangement using a method in which error correction is performed both before and after an interleaving process. The arrangement of FIG. 211 is similar to the arrangements of FIG. 1 and FIG. 202 except for design changes indicated hereinafter.

In the arrangement of FIG. 211, magnetic record data is ECC-encoded by a Reed-Solomon C2 error correction encoder 35a in an error correcting portion 35, and a C2 parity 45 is added thereto. Then, the resultant data is processed by an interleaving portion 35b as follows. Specifically, as shown in FIG. 212(a), data in a transverse direction 51a is read out along a longitudinal direction 51b so that the data is outputted as shown in FIG. 212(b). For example, data segments A1 and A2 are dispersed and separated by a dispersion length L1. Subsequently, a Reed-Solomon C1 error correction encoder 35c subjects the data to error correction encoding in the longitudinal direction, and a C1 parity is added thereto. The resultant data is magnetically recorded onto a recording medium.

In the arrangement of FIG. 211, during reproduction, data demodulated by an MFM demodulator 30d is subjected by a Reed-Solomon C1 error correcting portion to random error correction responsive to the C1 parity. Then, the data is mapped by the RAM 36x of the de-interleaving portion 36b in FIG. 208, being subjected to address conversion reverse to that of FIGS. 212(a) and 212(b). Therefore, the data is re-arranged into the original data along the transverse direction before being outputted. In this way, a burst error is dispersed and made into random errors. The random errors are corrected by a Reed-Solomon C2 error correcting portion 36a of FIGS. 212(a) and 212(b), and the error-free resultant data is recovered and outputted.

Since the arrangement of FIGS. 212(a) and 212(b) executes the error correction at two stages, that is, before and after the interleaving, burst errors can be effectively compensated. Although the single-stage error correction in FIG. 202 suffices as shown by the experimental data, it is preferable to use such two-stage error correction in recording and reproducing very important data.

DESCRIPTION OF THE SECOND PREFERRED EMBODIMENT

FIG. 19 shows a recording and reproducing apparatus according to a second embodiment of this invention which is similar to the recording and reproducing apparatus of FIG. 1 except that a magnetic head 8a and a magnetic head circuit 31a are added thereto.

As shown in FIG. 20, a magnetic head 8 executes magnetic recording on an entire region of a magnetic recording layer 3, the magnetic recording having a long recording wavelength. This process is similar to the corresponding process in the first embodiment. Subsequently, the magnetic head 8a executes magnetic recording on a surface portion 3a, the magnetic recording having a short recording wavelength. Consequently, the surface portion 3a and a deep layer portion 3b are subjected to the magnetic recordings of independent sub and main channels having a shorter wavelength and a longer wavelength respectively. In the case where a magnetic recording layer subjected to two-layer recording as shown in FIG. 20 undergoes a reproducing process by use of a magnetic head for a long wavelength such as the magnetic head for modulating the magnetic field in the first embodiment, information can be reproduced from the main channel. Thus, provided that summary information is recorded on the main channel while detailed information is recorded on the sub channel, the summary information can be reproduced by the system of the first embodiment and thus there will be an advantage such that the compatibility can be ensured between the apparatus of the first embodiment and the apparatus of the second embodiment.

FIG. 21 shows a case where only a short-wavelength magnetic head 8 is provided. In this case, a signal of the sub channel, on which a signal of the main channel is superimposed, is reproduced so that information of both the main and sub channels can be reproduced. When the structure of FIG. 21 is applied to an apparatus exclusively for reproduction, its cost can be low.

An upper part of FIG. 22 shows a case where recording is done by a magnetic head for modulating a magnetic field, that is, a magnetic head 8 for a long wavelength. As shown in the drawing, in the case where an N-pole portion is set "1" and a non-magnetized portion is set "0", recording is done as "0" in magnetization regions 120a and 120b and recording is done as "1" in a magnetization region 120c. Thus, a data sequence of "101" is obtained. As shown in a lower part of FIG. 22, in the case where an N-pole portion is set "1" and a non-magnetized portion is set "0" by using a short-wavelength magnetic head 8b for vertical, a data sequence of "10110110" is obtained. In this case, 8-bit information can be recorded on a region 120d equal in size to a region 120a in the upper part of the drawing. When the information is reproduced from the region 120d by the magnetic head 8, the reproduced information is decided to be "1" since there are only N-pole portions. This is the same as the region 120a. Thus, "1" in the data sequence 122a can be reproduced. In the case where an S-pole portion is defined as "0" and a non-magnetized portion is defined as "1" in a region 120e, 8-bit information, that is, a data sequence of "01001010", can be recorded. When this information is reproduced by the magnetic head 8, the reproduced information is decided to be "0" since there are only S-pole portions. This is one bit, and a signal equal in polarity to the signal on the region 120b is reproduced with a slightly-smaller amplitude. Thus, as shown in FIG. 22, the short-wavelength magnetic head 8b records and reproduces the signal of the data sequence 122a of the main channel D1 and the signal of the data sequence 122 of the sub channel D2, while the magnetic head 8 for modulating the magnetic field reproduces the data sequence 122a of the main channel D1. Accordingly, there will be an advantage such that the compatibility can be ensured. The gap of the magnetic head 8 for modulating the magnetic field is preferably equal to 0.2 to 2 .mu.m.

DESCRIPTION OF THE THIRD PREFERRED EMBODIMENT

FIG. 23 shows a recording portion of a third embodiment of this invention. In the third embodiment, a reflecting film 84 provided with pits as shown in FIG. 9 was formed on a transparent substrate 5 for a recording medium 2, and a magnetic recording film 3 was provided. This process is similar to the corresponding process in the first embodiment except that a film of Co-ferrite was formed by plasma CVD or others. This material has a transparency, and it has a high light transmissivity when its thickness is small.

As shown in FIG. 23, light emitted from an optical head 6 is focused into a spot 66 on the recording medium from the back side thereof. The optical head 6 has a lens 54 which is connected to a slider 41 by a connecting portion 150. The connecting portion 150 has a spring effect. The slider 41 is made of transparent material. A magnetic head 8 is embedded into the slider 41. Thus, the optical head 6 reads the pits in the reflecting film 84 from the back side, and thereby tracking and focusing are controlled. Thus, the slider 41 connected thereto is subjected to tracking control so that the optical head 6 can follow a given optical track. A positional error between the lens 54 and the slider 41 is caused by only the spring effect of the connecting portion 150, and the slider 41 is controlled with an accuracy of a micron order. Upward and downward head movement is done together with the focusing control, and the movement is controlled with an accuracy of an order of several microns to several tens of microns.

Segments of information are sequentially recorded on the magnetic recording layer 3 by magnetic recording. In this embodiment, since optical tracking is enabled, there is a remarkable advantage such that a track pitch of several microns can be realized. Since the slider 41 and the magnetic head 8 are moved upward and downward according to the focusing control, a given track can be correctly followed by the magnetic head 8 even when the surface accuracy of the substrate 5 of the recording medium 2 is low. Thus, it is possible to use a substrate having a low surface accuracy. Accordingly, there is an advantage such that an inexpensive substrate, for example, a plastic substrate or a non-polished glass substrate, can be used which is much cheaper than a polished glass substrate.

FIG. 23 shows the case where the optical head 6 executes the information reproduction on the recording medium 2 from the back side thereof. The information reproduction can also be done on the recording medium 2 by a mechanism such as a conventional optical disk player from the upper side thereof, and thus there is an advantage such that the compatibility can be ensured. In addition, there is a notable advantage such that a memory capacity greater than that in a conventional case by one or more orders can be realized by using the optical tracking.

DESCRIPTION OF THE FOURTH PREFERRED EMBODIMENT

FIG. 24 shows a recording and reproducing apparatus according to a fourth embodiment of this invention which is similar to the recording and reproducing apparatus of FIG. 1 except for design changes indicated hereinafter. In the first embodiment, the magnetic head 8 uses the magneto-optical recording head for modulating the magnetic field as it is, and the vertical recording is done as shown in FIG. 3. On the other hand, in the fourth embodiment, as shown in FIG. 25, a magnetic head 8 has the function of horizontal magnetic recording and also the function of magneto-optical recording magnetic-field modulation, and the magnetic head 8 is used to execute horizontal recording on a magnetic recording layer 3 of a recording medium 2.

An equivalent head gap of the magnetic-field modulating head in the first embodiment, for example, a head for an MD (a minidisk), is generally 100 .mu.m or greater, so that the recording wavelength .lambda. is several hundreds of .mu.m. In this case, a counter magnetic field is generated and thus a magnetism effectively used for actual recording is reduced, so that the level of a reproduced output is lowered. The first embodiment has a remarkable advantage such that a cost increase is prevented since a change of the structure is unnecessary, but the level of a reproduced output tends to be low.

In the case where a high level of a reproduced output is required with respect to long-wavelength recording, horizontal recording is preferable. In order to realize the horizontal recording, the fourth embodiment is modified from the first embodiment in a manner such that the structure of a magnetic head is changed and a recording system is changed from vertical recording to horizontal recording.

As shown in FIG. 25, the magnetic head 8 of the fourth embodiment has a main magnetic pole 8a, a sub magnetic pole 8b, a head gap 8c, and a winding 40. The main magnetic pole 8a has the function of a magnetic head for modulating a magnetic field. The sub magnetic pole 8b serves to form a closed magnetic circuit. The head gap 8c has a gap length L. During horizontal recording, the magnetic head 8 is regarded as a ring head having a gap length L. The magnetic head 8 is designed so as to apply a uniform magnetic field to an optical recording layer 4 during the magneto-optical recording of the magnetic field modulation type.

In the case of a magnetic recording mode of operation which is shown in FIG. 25, light emitted from the optical head 6 is focused into a spot 66 on the optical recording layer 4, and the optical head 6 reads out track information or address information therefrom. The optical head 6 is subjected to tracking control so that a given optical track can be scanned. Thus, the magnetic head 8 connected to the optical head 6 travels on a given magnetic track. As shown in FIG. 25, while the recording medium 2 is moved in a direction 51, horizontal magnetic signals 61 are sequentially recorded in the magnetic recording layer 3 in accordance with an electric information signal fed from a magnetic recording block 9. When the gap length is denoted by L and the recording wavelength is denoted by .lambda., there is a relation as .lambda.>2L. Thus, as the gap length L is decreased, a recording capacity is greater. In the case where the gap length L is reduced, a region subjected to a uniform magnetic field is narrowed during the generation of a modulation magnetic field for the magneto-optical recording. Thus, in this case, the recordable region with respect to the light spot 66 provided by the optical head 6 is narrowed and it is necessary to increase the accuracy of the sizes of the recording medium and the tracking mechanism, and thus the cost tends to be increased.

In the case of the execution of the magneto-optical recording as shown in FIG. 26, a spot 66 of laser light from the optical head 6 heats the corresponding point of the optical recording layer 4 to a temperature equal to or higher than a Curie temperature thereof. The point of the optical recording layer 4 which is exposed to the light spot 66 is magnetized in accordance with a modulation magnetic field generated by the magnetic head 8, and segments of an information signal 52 are sequentially recorded on the optical recording layer 4. The positional relation between the optical head 6 and the magnetic head 8 is affected by the accuracy of the size of the tracking mechanism which includes a head base 19. In the case of an MD, to lower the cost, the standard of the size accuracy is lenient. Thus, when worst conditions are considered, there is a chance that the positional relation between the optical head 6 and the magnetic head 8 is greatly out of order. Accordingly, it is preferable that the area of a region 8e exposed to a uniform magnetic field is as large as possible.

As shown in FIG. 26, the main magnetic pole portion 8a of the magnetic head 8 is formed with a tapered condensing section 8d, and thereby right-hand magnetic fluxes 85a and 85b are condensed so that a magnetic field is strengthened. Thus, the magnetic fluxes 85a and 85b are made equivalent to magnetic fluxes 85c, 85d, 85e, and 85f, and there is an advantage such that the region 8e exposed to a uniform magnetic field is enlarged. In this way, even when the relative position between the optical head 6 and the magnetic head 8 moves out of the correct position so that the relative position between the light spot 66 and the magnetic head 8 also moves out of the correct position, an optimal modulation magnetic field is applied to the optical recording layer 4 provided that the light spot 66 exists within the region 8e exposed to the uniform magnetic field. Accordingly, the magneto-optical recording is surely executed, and an error rate is prevented from being worse.

As shown in FIG. 31, magnetic fluxes of the magnetically recorded signal 61 on the magnetic recording layer 3 are formed as magnetic fluxes 86a, 86b, 86c, and 86d. During the magneto-optical recording, the portion of the magneto-optical recording material which is heated by the light spot 66 to a temperature equal to or higher than the Curie temperature thereof is subjected to the magnetic field of the magnetic flux 86a by the magnetically recorded signal 61 and also the modulation magnetic field from the magnetic head 8. When the magnetic field of the magnetic flux 86a is stronger than the modulation magnetic field from the magnetic head 8, the magneto-optical recording responsive to the modulation magnetic field can not be correctly done. Thus, it is necessary to limit the magnitude of the magnetic flux 86a to a given level or less. Accordingly, an interference layer 81 having a thickness d is provided between the magnetic recording layer 3 and the optical recording layer 4 to reduce the adverse influence of the magnetic flux 86a. When the shortest recording wavelength is denoted by .lambda., the strength of the magnetic flux 66 at the optical recording layer 4 is attenuated by about 54.6.times.d/.lambda.. In the case of a recording medium, it can be thought that various recording wavelengths .lambda. are used. It is general that the shortest recording wavelength is equal to 0.5 .mu.m. In this case, when the thickness d is 0.5 .mu.m, attenuation of about 60 dB is obtained so that the adverse influence of the magnetically recorded signal 61 hardly occurs.

As previously described, by using an interference film of a thickness of 0.5 .mu.m or greater between the magnetic recording layer 3 and the optical recording layer 4, there is provided an advantage such that the magnetically recorded signal hardly affects the magneto-optical recording. The interference film is preferably made of non-magnetic material or magnetic material having a weak coercive force.

In the case where the magneto-optical recording and the magnetic recording are done by using a magneto-optical recording medium, a modulation magnetic field is prevented from injuring a recorded magnetic signal provided that the modulation magnetic field for the magneto-optical recording is sufficiently weaker than the coercive force of magnetic material for a magnetic recording layer. When a ring-type head is used as in the previously-mentioned case, a strong magnetic field occurs in a head gap portion. Thus, even if the modulation magnetic field is weak, there is a chance that the modulation magnetic field adversely affects a recorded magnetic signal and thus an error rate is increased. This problem is resolved as follows. In the case of recording on a magneto-optical recording medium, as shown in FIG. 27, before the optical head 6 records a main information signal on the optical recording layer, an information signal magnetically recorded on a magnetic track 67g at the opposite side of an optical track 65g to be scanned is transferred to the memory 34 in the recording and reproducing apparatus or written on the optical recording layer to be saved. The saving prevents a problem even when recorded data in the magnetic recording layer are damaged by the modulation magnetic field during the magneto-optical recording.

A system controller 10 operates in accordance with a program stored in an internal ROM. FIG. 28 is a flowchart of this program. The program of FIG. 28 is divided into six large blocks. A decision block 201 decides the character of a disk. In the case of a ROM disk, an exclusive-reproduction block 204 is used. In the case of reproduction on an optical RAM disk, a reproduction block 202 is executed and sometimes a reproduction/transfer block 203 is executed. In the case of recording on an optical RAM disk, a recording block 205 is used and sometimes a recording/transfer block 206 is used. In the presence of a free time, only transfer is executed by a transfer block 207.

The program of FIG. 28 will now be described in more detail. In the decision block 201, a step 220 places a recording medium 2, that is, a disk, into a correct position or an operable position. A step 221 decides the type of the disk by detecting a click on a disk cassette such as shown in FIG. 16. There are various disk types such as a ROM, a RAM, an magneto-optical recording medium, an optical recording prevention disk, and a magnetic recording prevention disk. A subsequent step 222 moves the optical head 6 to a position aligned with an inner most optical track 65a and an innermost magnetic track 67a. A step 223 reads out magnetic information data and optical information data from a TOC region of the recording medium. In the case of a music disk, data is inputted which represents a music number at the end of previous operation. In the case of a game disk, data is inputted which represents a stage number at the previous end of the game. As shown in FIG. 16, when the user desires continuation in response to the inputted data, conditions at the end of previous operation are retrieved. A step 224 reads out an un-transfer flag from the magnetic TOC region. The un-transfer flag being "1" represents that magnetic data which is not transferred to an optical data section remains. The un-transfer flag being "0" represents it does not remain. A step 225 decides whether the disk is a magneto-optical disk or a ROM disk. When the disk is a ROM disk, an advance toward a step 238 is done. When the disk is a magneto-optical disk, an advance toward a step 226 is done. When the step 238 detects the presence of a reproducing instruction, a step 239 reproduces an optically recorded signal and a magnetically recorded signal. When the operation ends at a step 240, a step 241 writes information into the TOC region of the magnetic track. The written information represents various changes occurring during the reproduction, for example, changes in the music reproduction order, and the music number at the end of the operation. After writing the information is completed, a step 242 ejects the disk.

As previously described, when the disk is a magneto-optical disk, an advance toward a step 226 is done. In the presence of a reproducing instruction, an advance to a step 227 is done. Otherwise, an advance to a step 243 is done. The step 227 executes reproducing a main recorded signal on an optical recording surface at a speed higher than a normal reproduction speed, and sequentially stores the reproduced information into a memory. In the case of a music signal, an amount of data which corresponds to several seconds can be stored. Thus, even if the reproduction is interrupted, reproduced music can be continued. When a step 228 detects that the memory is completely filled with the reproduced information, a step 229 is executed. When the step 229 decides that an un-transfer flag is "1", the reproduction of the main recorded signal is interrupted and an advance to a step 230 in the reproduction/transfer block 203 is done. A check is made as to whether or not all of a sub recorded signal on a magnetic recording surface has been reproduced. When the result of the check is Yes, an advance to a step 234 is done. Otherwise, an advance to a step 231 is done, and the sub recorded signal on the magnetic recording surface is reproduced and the reproduced information is stored into the memory. A step 232 checks whether or not outputting the stored main recorded signal such as the music signal is still possible. When the result of the check is No, a return to the step 227 is done and reproducing and storing the main recorded information are executed. In the case where the result of the check is Yes, at the moment at which the sub recorded signal reaches a preset memory amount in a step 233, the step 234 again checks whether or not storing and reproducing the main recorded signal can be done. When the result of the check is Yes, a step 235 transfers and writes the sub recorded signal from the memory into a transfer region on the optical recording surface. Then, a step 236 checks whether or not transferring all the data is completed. When the result of the check is No, a return to the step 230 is done and the transfer is continued. When the result of the check is Yes, a step 237 changes the un-transfer flag from "1" to "0" and then a return to the step 226 is done.

In the case of recording on the optical recording layer, an advance to a step 243 in the recording block 205 is done, and a check is given with respect to a recording instruction. When the result of the check is Yes, a step 244 executes storing the main recorded signal into the memory and the optical recording is not executed. A step 245 checks whether or not the memory has a free area. When the result of the check is No, a step 245a executes the optical recording of the main recorded signal and a return to the step 243 is done. When the result of the check is Yes, an advance to a step 246 is done. When the un-transfer flag is not "1", a return to the step 243 is done. Otherwise, an advance to a step 247 in the recording/transfer block 206. The step 247 stores the main recorded signal into the memory and simultaneously reproduces a sub recorded signal on a magnetic track 67g at the opposite side of an optical track 65g of FIG. 27 which is planned to be subjected to the optical recording at this time. In addition, the step 247 stores the reproduced sub recorded signal into the memory. A step 248 checks whether or not the memory has a free area. When the result of the check is Yes, a step 248a transfers and writes the sub recorded signal into the optical recording layer. When the result of the check is No, a return to the step 245a is done and the optical recording is executed. A step 249 checks whether or not transferring all the data has been completed. When the result of the check is Yes, a step 250 changes the un-transfer flag from "1" to "0" and then a return to the step 243 is done. Otherwise, nothing is done and a return to the step 243 is done.

The step 243 checks whether or not a recording instruction is present. When the result of the check is No, an advance to a step 251 in the transfer block 207 is done. Here, recording and also reproducing the main recorded signal are unnecessary, and thus only the transfer of a sub recorded signal from a magnetic data surface to an optical data surface is executed. The step 251 executes reproducing the sub recorded information and storing the reproduced sub recorded information into the memory. A step 252 executes the transfer of the sub recorded signal from the memory to the optical recording layer. A step 253 checks whether or not transferring all the data has been completed. When the result of the check is No, a return to the step 251 is done so that the transfer is continued. Otherwise, a step 254 changes the un-transfer flag from "1" to "0", and then a step 255 checks whether or not all the operation has been ended. When the result of the check is No, a return to the first step 226 is done. Otherwise, an advance to a step 256 is done, and the information which has been changed by this work and other information such as information representing that the un-transfer flag is "0" are magnetically recorded on the TOC region of a magnetic track. Then, a step 257 ejects the disk, and the work regarding this disk is ended.

It should be noted that the step 256 may again write all the sub recorded signal into the magnetic recording layer from the memory to return the magnetic recording layer to the conditions which occur before the execution of the optical recording.

As previously described, only the data in the magnetic track among the data on the magnetic recording surface, which might be damaged by a modulation magnetic field during the optical recording, is transferred and saved into the memory or the optical recording surface. Thus, there is an advantage such that a damage to the data on the magnetic recording surface can be substantially prevented.

Optical recording may be done by recording saved data on a magnetic track again and retrieving the saved data after the work of optical recording. In this case, there is an advantage such that data on a magnetic recording surface is retrieved upon the ejection of a disk.

The design of FIG. 28 uses a method where data on a magnetic recording surface, which might be damaged, is transferred to an optical recording surface before magneto-optical recording is done. On the other hand, a design of FIG. 29 uses a method where data transfer to an optical recording surface is not executed. A decision block 201, a reproduction block 202, and an exclusive reproduction block 204 of FIG. 29 are similar to those of FIG. 28, and a description thereof will be omitted. Since the data transfer is not executed, it is unnecessary to provide a reproduction/transfer block 203, a recording/transfer block 206, and a transfer block 207. A recording block 205 of FIG. 29 differs from that of FIG. 28, and a detailed description thereof will be given hereinafter.

A step 226 in the reproduction block 202 checks whether or not a reproducing instruction is present. When the result of the check is No, an advance to a step 264 is done. Otherwise, an advance to a step 260 is done. The step 260 manages a processed optical track in unit of a magnetic track, and a calculation is given of a magnetic track at the opposite side of an optical track which may be damaged by magneto-optical recording. In addition, a check is made as to whether or not the present track is the same as the track subjected to previous saving. When the result of the check is Yes, a step 263 executes magneto-optical recording on the optical track. Otherwise, a step 261 writes the saved data into the previous magnetic track, and thereby the data on the previous magnetic track can be fully retrieved. Next, a step 262 reads out data from the magnetic track which may be damaged at this time, and saves the readout data into the memory. Then, a step 263 executes recording on the optical track, and a return to a step 243 is done. When the result of a check by the step 243 is No, a step 261a retrieves the previous conditions of the magnetic track. Thereafter, a step 264 in an end block 206A checks whether or not the operation is ended. When the result of the check is No, a return to the step 226 is done. Otherwise, a step 265 executes magnetically recording information which has been changed during the interval from the placement of the disk to the end, for example, information of the ending music number. Then, a step 266 ejects the disk. In this way, the work is ended. When a next disk is placed into an apparatus, the work is started again at the step 220.

In the design of FIG. 28, all the magnetic data is transferred to the optical recording layer to cope with a damage to the magnetic data by the magneto-optical recording. On the other hand, in the design of FIG. 29, magnetic data is managed in unit of a magnetic track, and reading is given on only magnetic data from a magnetic track which may be damaged by the magneto-optical recording. The readout data is stored into the memory. When the magnetic track is damaged by the magneto-optical recording and optical recording on another magnetic track is done, the former magnetic track is completely retrieved. Thereby, a memory capacity which corresponds to one magnetic track to three magnetic tracks suffices, and the capacity of the memory can be relatively small. As made clear from FIG. 29, the design of this drawing has an advantage such that a simple process can protect magnetic data from being damaged by the magneto-optical recording.

As shown in FIGS. 30(a) and FIG. 30(b), a reproducing process can be given on a magneto-optical disk and a CD by using a same mechanism. In the case of a CD, since a protective cartridge is absent, the CD tends to be affected by an external magnetic field. By setting a magnetic coercive force in a magnetic recording layer 3 of a CD to 1,000 to 3,000 Oe and thus making it much stronger than that in a magnetic recording layer of a magneto-optical recording medium, there is provided an advantage such that magnetic data can be prevented from being damaged by an external magnetic field. In the case of a magneto-optical disk, if a magnetic coercive force is increased to a level near the magnitude of a modulation magnetic field, the magnetic coercive force can provide an adverse influence. Thus, the magnetic coercive force is set to 1,000 Oe or less.

DESCRIPTION OF THE FIFTH PREFERRED EMBODIMENT

FIG. 32 shows a recording and reproducing apparatus according to a fifth embodiment of this invention which is similar in basic operation to the apparatus of FIG. 1 and FIG. 24 related to the first embodiment and the fourth embodiment. The fifth embodiment differs from the first embodiment in the following points.

As shown in FIG. 33, the fifth embodiment includes two windings, that is, a magnetic-field modulating winding 40a and a magnetically recording winding 40b. With reference to FIG. 32, during the magnetic recording or reproduction, a magnetic head circuit 31 feeds or receives a current to or from the magnetic recording winding 40b to execute the magnetic recording or reproduction.

During the execution of the magneto-optically recording of the magnetic-field modulation type, a magnetic-field modulating circuit 37a in an optical recording circuit 37 feeds a modulation signal to the magnetic-field modulating winding 40a to realize the magneto-optical recording.

With reference to FIG. 33, a description will now be given of operation of the recording and reproducing apparatus which occurs during the magnetic recording and reproduction. A recording current fed from the magnetic head circuit 31 flows in a direction denoted by the arrow in the drawing. Thus, a magnetic closed circuit of magnetic fluxes 86c, 86a, and 86b is formed, and time segments of an information signal 61 are sequentially recorded on a magnetic recording layer 3. The magnetic recording is done in a horizontal direction. In this case, no current is basically fed to the magnetic-field modulating winding 40a. In this structure, a closed magnetic circuit including a gap 8c is formed, and optimal designing of a reproduction sensitivity is enabled.

With reference to FIG. 34, a description will now be given of operation of the recording and reproducing apparatus which occurs during the magneto-optical recording. The magnetic-field modulating winding 40a is wound on a main magnetic pole 8a and a sub magnetic pole 8b of a yoke in equal directions. Thus, when a modulating current flows from the magnetic-field modulating circuit 37a in a direction 51a, downward magnetic fluxes 85a, 85b, 85c, and 85d occur. Magneto-optically recording material in a point of an optical recording layer 4, which is exposed to a light spot 66 and which is heated to a Curie temperature thereof or higher, undergoes magnetization inversion in response to the magnetic field so that an information signal 52 is recorded. In this case, the strength of the magnetic field at the light spot 66 is generally set to 50-150 Oe in a region 8e exposed to a uniform magnetic field. As shown in FIG. 25, it is preferable to provide an interference layer 81 to prevent the magneto-optical recording material from being subjected to magnetization inversion in response to an information signal 61. It is good to set the thickness d of the interference layer 81 as .lambda.>d.

The structure of FIG. 34 has an advantage such that the region 8e exposed to the uniform magnetic field can be wide. In addition, since recording heads can be independently designed with respect to the two windings, there is provided an advantage such that optimal magnetic-field modulating characteristics, optimal magnetic recording characteristics, and optimal magnetic reproducing characteristics can be attained. Since the head gap 8c of FIG. 33 can be small, it is possible to shorten the wavelength which occurs during the magnetic recording. Since optimal designing of the formation of a closed magnetic field is enabled, the reproduction sensitivity can be enhanced. As shown in FIG. 34, during the magnetic-field modulation, the magnetic flux 85a of the main magnetic pole 8a and the magnetic flux 85d of the sub magnetic pole 8b extend in the equal directions, so that a strong magnetic field does not occur in the gap 8c but only a weak magnetic field corresponding to the modulation magnetic field occurs. Since a magnetic coercive force in the magnetic recording layer 3 is 800-1,500 Oe and is adequately stronger than the modulation magnetic field and since there is an easily magnetized axis in a horizontal direction, there is provided an advantage such that a magnetically recorded signal 61 is prevented from being damaged by the modulation magnetic field. Thus, by setting the magnetic coercive force Hc of the magnetic recording layer 3 stronger than the recording magnetic field Hmax applied to the magneto-optical recording material, a damage to the data is prevented. In the case of the provision of an allowance corresponding to double, it is good to maintain a relation as Hc<2 Hmax. In addition, it is good to fabricate a recording medium 2 shown in FIG. 8. As shown in FIG. 35, in a magnetic head 8, windings 40a and 40b may be separately wound on a main magnetic pole 8a and a sub magnetic pole 8b respectively. In this case, during the magnetic-field modulation, a modulating current is also driven through the magnetic recording winding 40b in a direction 51b by using a magnetic head circuit 31, and thereby a magnetic flux 85d occurs which extends in a direction equal to the directions of the magnetic fluxes 85c, 85b, and 85a. Thus, it is possible to obtain an advantage similar to the advantage of the design of FIG. 34.

As shown in FIG. 36, a tap 40c may be provided to a single winding to form two divided sub windings having three terminals. During the magnetic recording, the tap 40c and a tap 40e are used. During the magneto-optical recording, as shown in FIG. 37, a tap 40d and a tap 40e are used to generate a modulating magnetic field for the mag