Electronic franking machines

Abstract

An electronic franking machine, for example a postal franking machine, has a digital electronic input register, for storing a selected franking value fed in for use in the next franking operation of the machine, and a digital electronic total register which accumulates an indication of the total of the respective franking values used for such operations of the machine since this register was last reset. The machine also has an electrically adjustable printing device, for printing the selected franking value in each franking operation. The printing device is housed in a relatively massive stationary unit of the machine, and the electronic registers and associated circuitry are housed in a relatively light portable unit that is readily separable from the stationary unit to facilitate resetting by a remote authority.

Claims

We claim:

1. In an electronic franking machine comprising:

franking value selection means, operable selectively to provide an electrical input representative of a franking value selected for a desired next franking operation of the machine, for setting the selected franking value into the machine;

a digital electronic input register, having an input connected to said franking value selection means, for receiving and holding said selected franking value;

an electrically adjustable printing device, settable electrically to any selected one of a plurality of different conditions enabling the device to be actuated respectively to print a plurality of different franking values;

setting control circuitry, connected with said input register and said printing device, operable in dependence upon said electrical input to bring about setting of said printing device to the condition in which it is actuable to print said selected franking value;

a digital electronic total register, for holding an accumulated value representative of the sum of the respective franking values used in preceding franking operations of the machine; and

totalling circuitry, connected between said input register and said total register, for effecting addition of said selected franking value held in the input register to said accumulated value; whereby a new accumulated value is provided, to be held in said total register, after printing of said selected franking value, in place of said accumulated value previously held there,

the improvement wherein said machine comprises an electronics unit which houses franking value selection means, said input register, said total register and said totalling circuitry and a separate printing unit which houses the said electrically adjustable printing device and with which said electronics unit is engaged during the operation of the machine, said electronics and printing units being readily separable one from the other and having complementary coupling means for setting up operative electrical connections therebetween when the electronics unit is engaged with the printing unit.

2. A machine as claimed in claim 1, wherein said total register is a non-volatile store.

3. A machine as claimed in claim 2, having an electrical mains input for receiving operating power for the machine from an external mains supply, further comprising capacitive storage means connected to store electrical energy and to deliver that stored energy in the event of failure of said external mains supply in the course of such an addition, whereby the addition can be completed after such failure.

4. A machine as claimed in claim 2, wherein said total register comprises an MNOS storage array.

5. A machine as claimed in claim 1, having an electrical mains input for receiving operating power for the machine from an external mains supply, wherein said total register is a volatile store, the machine further comprising auxiliary supply means including a battery, operable to provide an electrical supply for said total register from said battery in the event of failure of said external mains supply, for energizing the total register to retain the said accumulated value after such failure.

6. A machine as claimed in claim 1, having an electrical mains input for receiving operating power for the machine from an external mains supply, wherein the said total register is a volatile store, the machine further comprising back-up storage means operatively connected to said total register to receive said accumulated value in the event of failure of said external mains supply and to retain said accumulated value therein after such failure.

7. A machine as claimed in claim 6, wherein said back-up storage means comprise a volatile back-up store and battery supply means connected to supply operating power to said volatile back-up store in the event of such failure.

8. A machine as claimed in claim 6, further comprising idle-state monitoring means connected to bring about transfer of said accumulated value stored in said total register to said back-up storage means upon elapse of a predetermined period of time since completion of the last preceding franking operation.

9. A machine as claimed in claim 6, wherein said back-up storage means comprise a non-volatile back-up store in which the acumulated value received is retained.

10. A machine as claimed in claim 9, further comprising auxiliary battery supply means connected to supply operating current to parts of the machine that effect transfer of said accumulated value to said non-volatile back-up store in the event of such failure.

11. A machine as claimed in claim 9, wherein said non-volatile back-up store comprises an MNOS storage array.

12. A machine as claimed in claim 1, further comprising:

a digital electronic credit register, housed in the said electronics unit, for holding a current credit value produced by subtraction of the respective franking values used in preceding franking operations of the machine from a maximum credit value preset in said credit register; and

subtraction circuitry, housed in the said electronics unit and connected between said input register and said credit register, for effecting subtraction of said selected franking value held in said input register from said current credit value, whereby a new current credit value is provided to be held in said credit register, after said printing, in place of said current credit value previously held there.

13. A machine as claimed in claim 12, having an electrical mains input for receiving operating power for the machine from an external mains supply, wherein said credit and total registers are volatile stores, the machine further comprises auxiliary supply means including a battery, operable to provide an electrical supply for said credit and total registers and said totalling circuitry and subtraction circuitry in the event of failure of said external mains supply, for energising said credit register to retain said current credit value, and said total register to retain said accumulated value, after such failure.

14. A machine as claimed in claim 12, having an electrical mains input for receiving operating power for the machine from an external mains supply, wherein said credit and total registers are volatile stores, the machine further comprising back-up storage means operatively connected to said credit and total registers to receive said current credit value from the credit register and said accumulated value from said total register, and to retain those values, in the event of failure of said external mains supply to the machine.

15. A machine as claimed in claim 12, wherein said back-up storage means comprise a non-volatile back-up store connected to receive said current credit value and said accumulated value in the event of such failure of external mains supply.

16. A machine, as claimed in claim 15, further comprising auxiliary battery supply means connected to supply current to parts of the machine that effect transfer of said current credit value from said credit register, and said accumulated value from said total register, to said non-volatile back-up store in the event of such failure.

17. A machine as claimed in claim 15, wherein the said credit and total registers are non-volatile stores.

18. A machine as claimed in claim 17, further comprising capacitive storage means connected to store electrical energy and to deliver that stored energy in the event of failure of said external mains supply in the course of such addition and such subtraction, whereby the addition and the subtraction can be completed after the failure.

19. A machine as claimed in claim 17, wherein said credit register comprises an MNOS storage array and said total register comprises an MNOS storage array.

20. A machine as claimed in claim 12, wherein the said totalling means the said subtraction means comprise a CMOS IC (complementary-metal-oxide-semiconductor integrated circuit).

21. A machine as claimed in claim 12, further comprising printing-device monitoring means connected to monitor response of the printing device to operation of said setting control means and operable to de-actuate the printing device if correct setting thereof to said selected franking value is not completed by the end of a preselected period of time of operation of said setting control means.

22. A machine as claimed in claim 12, further comprising, housed in the said electronics unit, an auxiliary register and associated circuitry components operable to accumulate and store in the auxiliary register a count of the number of franking operations that have been carried out by the franking machine using a particular preselected franking value.

23. A machine as claimed in claim 12, wherein the said franking value selection means comprise a key-board operable for selecting such a franking value, and further comprise display means operable to display a franking value selected.

24. A machine as claimed in claim 23, wherein the said keyboard includes keys and respective associated circuitry components which are selectively actuable to cause the value stored in any selected one of the registers to be displayed by the said display means.

25. A machine as claimed in claim 23, further comprising, housed in the said electronics unit, value adjustment enabling means operable to enable the value stored in at least one of the registers to be changed selectively while the machine is not being used to carry out franking operations.

26. A machine as claimed in claim 25, wherein such operation of the value adjustment enabling means permits the value stored in at least one of the registers to be so changed by operation of keys on the said key-board.

27. A machine as claimed in claim 25, wherein a locking device, having locked and unlocked conditions, is provided, in the said electronics unit, which must be placed in said unlocked condition before the value adjustment enabling means can be so operated, thereby to restrict access to the said value adjustment enabling means.

28. A machine as claimed in claim 27, wherein the said locking device can be changed from said locked condition into said unlocked condition by use of the said key-board to key in a predetermined code sequence.

Description

The present invention relates to electronic franking machines.

In the field of postal franking, previously-used machines have employed mechanical or electro-mechanical systems for selection of digits representing values to be franked (on an envelope, for example), for metering individual franking operations (recording and collating amounts franked, for example) and for storage of information concerning, for example, total value franked to date. Setting of a value to be franked is carried out mechanically by selecting an angular position for a numbered wheel, which position is retained once set, Such a mechanical machine is described, for example, in U.S. Pat. No. 3,451,519. Incidentally, an electrically adjustable printing device is disclosed in U.S. Pat. No. 3,869,986, but even this does not suggest any departure from the conventional use of cumbersome electromechanical meter memories.

Although such previously used systems are well proven, it is desirable to provide franking-value selection and registration means such as can enable a reduction in size and weight to be achieved, without significant loss of efficiency and reliability as compared with prior franking machines.

According to the present invention there is provided a franking machine, comprising:

FRANKING VALUE SELECTION MEANS, OPERABLE SELECTIVELY TO PROVIDE AN ELECTRICAL INPUT REPRESENTATIVE OF A FRANKING VALUE SELECTED FOR A DESIRED NEXT FRANKING OPERATION OF THE MACHINE, FOR SETTING THE SELECTED FRANKING VALUE INTO THE MACHINE;

A DIGITAL ELECTRONIC INPUT REGISTER, HAVING AN INPUT CONNECTED TO SAID FRANKING VALUE SELECTION MEANS, FOR RECEIVING AND HOLDING SAID SELECTED FRANKING VALUE;

AN ELECTRICALLY ADJUSTABLE PRINTING DEVICE, SETTABLE ELECTRICALLY TO ANY SELECTED ONE OF A PLURALITY OF DIFFERENT CONDITIONS ENABLING THE DEVICE TO BE ACTUATED RESPECTIVELY TO PRINT A PLURALITY OF DIFFERENT FRANKING VALUES;

SETTING CONTROL CIRCUITRY, CONNECTED WITH SAID INPUT REGISTER AND SAID PRINTING DEVICE, OPERABLE IN DEPENDENCE UPON SAID ELECTRICAL INPUT TO BRING ABOUT SETTING OF SAID PRINTING DEVICE TO THE CONDITION IN WHICH IT IS ACTUABLE TO PRINT SAID SELECTED FRANKING VALUE;

A DIGITAL ELECTRONIC TOTAL REGISTER, FOR HOLDING AN ACCUMULATED VALUE REPRESENTATIVE OF THE SUM OF THE RESPECTIVE FRANKING VALUES USED IN PRECEDING FRANKING OPERATIONS OF THE MACHINE; AND

TOTALLING CIRCUITRY, CONNECTED BETWEEN SAID INPUT REGISTER AND SAID TOTAL REGISTER, FOR EFFECTING ADDITION OF SAID SELECTED FRANKING VALUE HELD IN THE INPUT REGISTER TO SAID ACCUMULATED VALUE; WHEREBY A NEW ACCUMULATED VALUE IS PROVIDED, TO BE HELD IN SAID TOTAL REGISTER, AFTER PRINTING OF SAID SELECTED FRANKING VALUE, IN PLACE OF SAID ACCUMULATED VALUE PREVIOUSLY HELD THERE, WHEREIN SAID FRANKING VALUE SELECTION MEANS, SAID INPUT REGISTER, SAID TOTAL REGISTER AND SAID TOTALLING CIRCUITRY ARE TOGETHER HOUSED IN AN ELECTRONICS UNIT OF THE MACHINE, AND THE SAID ELECTRICALLY ADJUSTABLE PRINTING DEVICE IS HOUSED IN A PRINTING UNIT OF THE MACHINE, SAID ELECTRONICS AND PRINTING UNITS BEING SEPARABLE ONE FROM THE OTHER AND HAVING COMPLEMENTARY COUPLING MEANS FOR SETTING UP OPERATIVE ELECTRICAL CONNECTIONS THEREBETWEEN WHEN THE ELECTRONICS UNIT IS ENGAGED WITH THE PRINTING UNIT.

For present-day purposes the electronics unit will generally include key-board-operated input means connected to the input register and operable to feed respective selected franking values into that register for successive franking operations of the machine.

An electronic postal franking machine designed to have various overall advantages as compared with some previously used electro-mechanical machines; for example, lower cost, better reliability and consequent reduced maintenance requirements, reduced bulk and weight, and in particular the normal requirement for the registers of such a machine to be checked and reset by the postal authorities can be greatly facilitated by the removable nature of the electronics unit which can have the form of a pocket calculator and house such registers in a readily transportable item.

In an electronic franking machine intended for use as a postal franking machine in the United Kingdom, there is provided additionally a credit register, i.e. a memory for storing credit information. Initially a maximum credit value is set in this register, by the Post Office, and the franking value is subtracted automatically from the value remaining in the credit register, whenever a franking operation is carried out with the machine. For such use in the U.K. it is necessary that existing credit and total expenditure values can be retained, in the registers of the machine, for an extended period of non-use.

It is also necessary that such a machine should be reasonably secure, so that information stored cannot be modified by unauthorised persons (at least without leaving evidence thereof). In particular the total register should be relatively highly secure, whilst the credit register should be alterable by Post Office personnel, for example, (but not others) relatively easily. Credit and total registers should preferably not be alterable during normal servicing of the machine. One way of providing security of "tote" information in the total register may be to provide that this "tote" register is replaceable, so that a new register is introduced each time a credit limit is reached, the old "tote" register being retained by the Post Office. Alternatively the tote register may be resettable using secure procedures.

Reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of a machine embodying the present invention,

FIGS. 2 to 4 are diagrammatic block circuit diagrams of parts of respective embodiments of the present invention,

FIG. 5 shows a schematic external view of a part of an embodiment of the present invention,

FIGS. 6A and 6B are together a more detailed block diagram of an embodiment of the present invention,

FIGS. 7A and 7B and 7C are synoptic diagrams of respective parts of an operational algorithm of an embodiment of the present invention,

FIGS. 8A and 8B and 8C are synoptic diagrams of respective parts of an operational algorithm of another embodiment of the present invention,

FIG. 9 is a block diagram of an embodiment of the present invention, and

FIG. 10 is a perspective view of the exterior of a franking machine embodying the present invention.

FIG. 1 shows operational components of a postal franking machine that has a non-volatile backing store, or register, 1 (discussed in more detail hereinafter) in addition to working registers 2 (in a so-called working register stack).

The working registers 2 include an input or value register, for storing a selected value to be franked in the next franking operation, which value is entered by way of a keyboard 3, and also include a credit register and a tote register. The current credit and tote values stored may be displayed on a display 4 by actuation of appropriate keys of the keyboard 3. When a value to be franked is set in the input register, a printer 5 is set to a condition for printing the selected franking value. Thereafter upon actuation of a "frank" key on the keyboard 3, a printing head of the machine is caused to operate and the value thus franked is added to the accumulated value stored in the tote register to provide a new accumulated value therein, and subtracted from the credit value stored in the credit register to provide a new credit value therein, by means of an arithmetic unit 6 which provides both addition and subtraction means. In practice this function of such a manually operated "frank" key will be performed by an electromechanical or optical internal switch which is automatically tripped, to cause the printing head to operate, upon insertion into the machine of an item to be franked. The manual key FK can be adapted to be used just for the printing of labels to be attached to packages too large to be inserted into the machine.

The non-volatile backing register 1 is provided for storing the values last present in the tote and credit registers, to provide for retention of up-to-date information, in the event of loss of power supplied to the working registers.

It will be appreciated that for use in some countries the presence of a credit register is not required and that a machine embodying the present invention could be built without such a register.

A control unit 7 governs operation of the other components of the machine. In the illustrated embodiment of the invention the unit 7 includes a Post Office controller which enables credit and tote information to be modified. In FIG. 1, broken lines indicate control links between unit 7 and other parts of the apparatus.

The Post Office controller can be considered as comprising a secure section and a highly secure section. The secure section may have a sealed input, which can only be used by breaking of a Post Office seal, by means of which a value stored in the credit register can be altered. The highly secure section may also have a seal which must be broken if access is to be gained, but will comprise in addition a device such as a combination lock, intended to deny access to all but authorised users. This highly secure section of the Post Office controller provides for alteration of a value stored in the tote register.

As an alternative to such a combination lock, or in addition, it may be provided that a preselected code word known only to authorised personnel must be entered into the machine via a keyboard in order that modification of tote information (and possibly credit information) be permitted. It will be appreciated that for some uses such security of tote and credit registers might not be required. For example only the presence of a seal might be sufficient.

Such a franking machine embodying the present invention, for use in the U.K., stores credit and tote information in its registers in binary coded form.

The embodiment of the present invention illustrated in FIG. 1 comprises also mail counters 8. These counters can enable a daily record of the amount of mail franked to be compiled, the information being retrievable by actuation of an appropriate key on the key-board 3.

There are several different types of store, for digital information storage, presently available. Such stores may be classified into two groups: volatile and non-volatile stores.

Non-volatile stores are devices which retain their information even after removal of power supplies thereto, e.g. magnetic storage systems. Magnetic storage systems tend to be large in both physical size and memory capacity, and they may also be expensive, and in the franking machine embodiment illustrated in FIG. 1 these are not employed.

Volatile stores are devices which may loose their information when power supply is removed, e.g. generally available Bipolar/MOS Registers. However, by providing registers are battery supply to a volatile store an effectively non-volatile store may be obtained. retrievable

Thus, as shown in FIG. 2, a standby battery 16 may be provided, in a franking machine embodying the present invention, as auxiliary supply means, to take over power supply to a volatile store 11 (which may be used as a total register, for example) in the event of failure of mains power supply. In the embodiment of FIG. 2, the battery will also supply power to logic circuitry 10 so as to enable tote information, for example, to be modified in the absence of mains supply; however, in the illustrated embodiment the battery does not supply electromechanical components (e.g. a printer), since this might result in too great a power drain on the battery; accordingly, franking cannot take place when the "standby" battery 16 is supplying power.

Thus, in a comparison of the embodiments of the present invention of FIGS. 1 and 2, in the embodiment of FIG. 2 the function of the backing store of FIG. 1 is fulfilled by the volatile store 11 (of FIG. 2) in combination with battery 16, volatile store 11 also constituting working registers 2 (or at least part thereof) of FIG. 1.

However, as shown in FIG. 1, it is possible to provide a franking machine embodying the present invention in which working reegisters aree of a volatile type, there being a separate non-volatile "dump" or "backing" register 1 constituting back-up storage means provided for use in the absence of mains supply, information from the working registers being automatically stored in the "backing" register upon loss of supply, but being automatically reetrievable when supply is returned.

As shown in FIG. 3, in a franking machine embodying the present invention in which such a non-volatile "dump" or "backing" register 18 is provided as a non-volatile back-up store in addition to a volatile store 11, a battery 16 may also be provided to ensure that, in the event of loss of mains power, logic circuitry 10 can be operated together with the volatile store 11 to ensure that information is properly transferred to the backing register 18. In this case the electronic sections of the machine may also remain operable in the absence of mains supply but, as in the embodiment of FIG. 2, electromechanical components cannot be operated when mains supply is absent.

When a volatile store with a back-up battery is employed in an embodiment of the present invention to provide an effectively non-volatile register, the battery used must be highly reliable.

Two possible types of battery or cell are at present considered as probably providing the most desirable choices:

(i) a new Lithium cell, developed by Saft Ltd. This can be manufactured to a smaller size than a Standard U2 cell and each individual cell has a terminal voltage of around 3.2 volts. Such cells are of a non-rechargeable type, but have a shelf life of approximately ten years. When the battery is employed merely as a standby, current drain might be approximately 80 nanoamps (80 .times. 10.sup.-9) to store 20 digits (10 per memory) in the stores being supplied. Thus, retention over a number of years is possible. In use in an embodiment of the present invention, it can be arranged that such a battery is automatically cut out of circuit when the mains is applied, and vice versa. In embodiments of the invention such as are shown in FIGS. 2 and 3, for example, a mains power supply, of the franking machine, and a battery can be connected to a tote or credit register (the volatile store 11) through respective diodes 13 and 14. The battery provides lower voltage than the mains power supply. The capacitor prevents the power supply to the store 11 dropping below a preselected operating voltage when overcoming reverse bias on diode 13 or 14 during change-over from battery to mains power supply, or vice versa, respectively.

(ii) Rechargeable Nickel/Cadmium cells. These are usually of a similar size to the previously mentioned batteries. It can be arranged that automatic recharging takes place when the machine in which they are employed is in use and is receiving mains supply. However, in an embodiment employing such a cell it is to be noted that if the machine is left in an unused condition for more than four months it is possible that the information registered may change or be lost. In an embodiment in which this is a possibility, it can be arranged that any change in information in the store will always be down in value so that the liability will not be that of the Post Office.

Solid state circuitry in the embodiment of FIG. 1 incorporates the functions of the control unit 7, arithmetic unit 6, and Working Registers 2. Although discrete I.C.' s can be used as the basis of this circuitry, it is possible to implement the whole logic on a single chip in the form of an LSI device.

The two major classes of digital I.C. technology at present are the Bipolar and MOS classes. The Bipolar class can itself be divided into several classes, viz: Standard Bipolar, Isoplanar, Collector Diffusion Isolation and (I.sup.2 L)integrated injection logic. MOS devices can also be divided into five different classes, viz: P-Channel, N-Channel Complementary MOS (CMOS), VMOS and DMOS. Each of these classes is again sub-dividable into different classes according to the fabrication and structure of their gate region.

A brief survey of the various available functional logic blocks (only available for a limited number of the above-mentioned classes of I.C. technology) suggests that for a franking machine embodying the present invention, those belonging to the CMOS class might provide the best cost/performance trade-offs at present. Compared with other medium-speed (50 NS propagation delay) logic blocks, CMOS blocks have relatively low power dissipation, for example 10 NW per gate. For TTL (transistor transistor logic) blocks the equivalent value would be of the order of 1 mW. Further, CMOS blocks can tolerate a relatively wide range of power supply voltages, for example from 3V to 15V, thus reducing any need for regulation of the power supplies, and have a good immunity to noise, typically up to 45% of the supply voltage, so that they can be employed in an electrically noisy environment with little need for complex filtering or shielding arrangements.

CMOS blocks may be slightly inferior to TTL blocks in terms of speed, and lower in gate density per unit silicon area than N-Channel MOS blocks, but these disadvantages appear to be only of secondary importance for present purposes.

The TTL and CMOS blocks at present readily available are not exactly equivalent (CMOS blocks have additional functions), but for comparison purposes it can be said that CMOS blocks are generally more expensive for both small and large quantities of particular devices. However, overall system costs using CMOS blocks could be less, owing to cheaper power supply requirements. Where large quantities are involved, i.e. in excess of 25,000 per annum, special integrated circuits using either TTL or CMOS technology, e.g. custom built chips or Microprocesser units, become economically viable, and their use can result in savings in both component and assembly costs.

As discussed above, with reference to FIGS. 1 and 3, in one embodiment of the present invention providing a postal franking machine there are two types of memory arrangement, viz: Working registers and a backing register (a non-volatile store).

In addition to the working registers there may be a programme store in the control unit 7 of FIG. 1. Thus a programmeable store in the form of an ROM (Read Only Memory) or a PROM (Programmeable Read Only Memory) may be needed to store machine instructions (which may be in micro-code). CMOS technology can again be used, to conserve power.

As mentioned above, an intrinsically non-volatile back-up memory can be used in the above-described embodiment of FIGS. 1 and 3 for preserving credit and tote information even in the absence of mains power to the machine. In this case, the operating system can be such that the non-volatile backing register is kept idle during the course of normal operation of the machine, and when the machine has reached a quiescent or static state, and has remained in that state for a defined time (say tens seconds has elapsed since completion of a last preceding franking operation), idle-state monitoring means provide a control signal which automatically causes the non-volatile backing register to be updated with the latest contents of the credit and tote registers.

In computer systems, intrinsically non-volatile backing stores are usually magnetic in nature. Owing to their size/weight and power consumption (during operation) presently available magnetic stores are not entirely suited for use as backing registers in franking machines embodying the present invention. However, a practically non-volatile semiconductor store, known as an MNOS (Metal-Nitride-Oxide-Semiconductor) device has been identified which seems likely to satisfy the requirements for use as such a backing register. Storage time for such a device depends on the amplitude and duration of writing pulses employed therewith. Plessey and NCR market such devices in 64-bit (e.g. Plessey NOM 401C 8 .times. 8 MNOS array) and 1024-bit arrays. Such devices can be made with rated minimum storage times of 1 day, 1 year, and 100 years, respectively for write times (per word) of 1 microsecond, 100 micro-seconds, and 10 milliseconds.

The power consumption of these devices during dynamic states is very close to that typical of CMOS devices. However, they require special interfacing circuitry and need a relatively high negative supply voltage, in the region of -30V, during write/erase operations.

In an embodiment of the present invention such a 64-bit Plessey MNOS store can be used, write pulses having a pulse height of -35V and a duration of 100 .mu.sec, giving a storage time in the range from 5 to 10 years.

It is also possible that MNOS devices could be used as working tote and credit registers in an embodiment of the present invention, and thereby obviate any necessity for the additional provision of a "dump" or backing register.

An embodiment of the present invention employing such a non-volatile store (providing a tote and/or a credit register) is illustrated in FIG. 4. The non-volatile store is indicated at 19 and is provided with a capacitor 20, which is maintained in a charged condition when mains power supply is present, which when mains power is cut-off provides a temporary power supply so that information can continue to be safely entered into the store, to complete an already commenced storage cycle, when mains supply is unexpectedly lost. Thereafter, as opposed to the situation in the embodiments of FIGS. 2 and 3, the electronic logic circuitry 10 is inoperable, as are the electromechanical components 12, until mains supply power is restored.

Three shift registers, for example, can be used, in an embodiment of the present invention, as working registers to store franking value (current value to be franked), credit and tote data. The input register in an embodiment of the present invention can be a 4 .times. 4 bit (4 decimal digits) register and the credit and tote registers can be 10 .times. 4 bit (10 decimal digits, or 9 decimal digits plus a half) registers.

A wide range of seven-segment display units are available which can be considered for use in embodiments of the present invention. These include Filamentary, Gas Discharge, V.L.E.D. (Visible Light Emitting Diode), Liquid Crystal and phosphor-Diode devices. Bearing in mind such factors as cost, appearance and portability, for a franking machine embodying the present invention the type of display unit that at present seems to be most viable commercially is the V.L.E.D. unit.

Reliability and degradation seem to be the main problems with liquid crystal display units. The operational life of such a display unit may be as short as 200 hours. In comparison to this, V.L.E.D. units are showing m.t.b.f. (mean time between failures) values of greater than 200,000 hours when operating under quite severe environmental conditions.

In terms of current drain from a supply (which is one of the most important factors to consider in the design of an off-line battery-operated electronic franking machine) liquid crystal devices have an undisputed advantage. However, to counter this, V.L.E.D. devices have additional speed that can enable power consumption to be reduced through the use of multiplexing techniques.

A possible configuration for display means is shown at 50 in FIG. 5. The display illustrated comprises two portions, a diagnostic fault code (explained in more detail hereinafter) display portion 51 and a numerical display portion 52 for displaying credit tote and franking values for example.

For entering information to the franking machine of FIG. 2, and for serving other functions, e.g. providing for display of credit, tote and selected franking values on demand, a keyboard is provided, for example such as is provided for a pocket calculator. A possible key-board arrangement can be as shown at 3 in FIG. 5. In FIG. 5, keys of the keyboard are designated 53, and an on/off switch provided thereon is designated 54. The following is a Table of symbols used on the keyboard of FIG. 5, explanation of various terms used will be given hereinafter.

                  Table 1
    ______________________________________
    Key Board Legend: operation indicated
     1. 0 - 9         Value selection.
     2. L.B.          Label select.
     3. C.L.          Clear value.
     4. T.D.          Tote register display.
     5. H.V.          Set high value.
     6. F.K.          Operate machine.
     7. C.D.          Credit register display.
    Operable Only By Post Office:
     8. P.C.          Programme clear.
     9. C.R.          Modify credit register.
    10. T.R.          Modify tote register.
    11. +             Add value register to credit or
                      tote registers.
    13. -             Subtract value register from
                      credit or tote registers.
    13. CA:CB:CC:CD:  Security code buttons.
    ______________________________________

                  Table 2
    ______________________________________
    Keys    No.    Type    Function       Notes
    ______________________________________
    0-9     10     Single  Decimal Number
                   shot    Entry
    1/2     1      "       0.5 Entry
    TD      1      "       TR Display
    CD      1      "       CR Display
    FCD     1      "       F.C.C. Display   May be
    SCD     1      "       S.C.C. Display   included
    LCD     1      "       L.C. Display     in the
    TCD     1      "       T.C. Display     keyboard
    HV      1      "       Set High Value
    FK      1      "       Operate Franking
    CL      1      "       Clear Value or
                           Input Register
                           and Diagnostic
                           Codes
    PC      1      "       Programme Clear
    CR      1      "       Modify C.R.      Operable
    TR      1      "       Modify T.R.      only
    +       1      "       Add V.R. to C.R. by
                           or T.R.          Post
    -       1      "       Subtract V.R. from
                                            Office
                           C.R. or T.R.
     ##STR1##
            1      Single Pole
                           Post Office security switch
                   Double
                   Throw
    LC      1      Single  Lockout clear    Operable
                   Shot                     only by
    SCS*    4      "       Secret Code      Post
                           Switch           Office
                   Single
    LS      1      Pole    Label Selection
                   Single  Switch
                   Throw
    ______________________________________
     *SCS could be increased from 4 to 12 in number for production machines.

                  Table 3
    ______________________________________
    Code Letter     Fault indicated
    ______________________________________
    L               credit register value
                    less than selected franking
                    value
    P               printer error
    F               mains fault
    E               battery/supply too low
    H               total register value too high
                    (most significant digit = 9)
    ______________________________________

                  Table 3
    ______________________________________
                    Automatic operation
                    Manual operation
    I.R.            Value or Input Register
    C.R.            Credit Register
    T.R.            Tote Register
    N               A Programmeable Number
    F.C.C.          First Class Counter
    S.C.C.          Second Class Counter
    L.C.            Label Counter
    T.C.            Total Item Counter
    P.O.S.          Post Office Security Switch
    H.V.            High Value
    F.K.            Frank
    Diagnostic code:
    L               C.R. Too Low
    H               T.R. Too High
    P. Printer Setting Error
    E               Battery Voltage Too Low
    ______________________________________
     Note:-
     *At any one time the following items are displayable via Key Board:
     F.C.C., S.C.C., L.C., T.C., C.R., and T.R.

• Inventors
  Fuller, Paul; Gillender, John Brian; Shacklady, Michael; Basu, Samir;
• Assignee
  Vickers Limited (London, EN)
• Published
  Jun-6-1978
• Current US Classes:
  705/405
• Application #
  746490
• International Classes
  G06F 015/28; G06F 003/12; G06F 003/02
• Field of Search
  364/200 235/151.33 235/92 177/25
• Examiner
  Thomas; James D.
• Agent
  Larson, Taylor and Hinds
• US Patent References:
  3938095
  3951221
  3978457
  4001568