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.

A 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, which device may be housed in a relatively massive stationary unit of the machine, the electronic registers and associated circuitry being housed in a relatively light portable unit that is received in nested relation in and, readily separable from, the stationary unit to facilitate resetting by a remote authority.

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

totaling 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 , for example, is composed of two mutually separable main parts, one of which comprises the printing unit, or module (PRINT HEAD), and the other being an electronics unit, or module, of approximately the size of a pocket calculator, which houses the registers and logic circuitry and includes the display and the keyboard. The electronics unit and printing module have complementary coupling means (for example, conventional plug and socket arrangements) for setting up operative electrical connections between the circuitry and the printing device when they are engaged. The exterior appearance of such a machine is illustrated in FIG. 10 in which 100 is the detacheable electronics unit and 101 is the printing module. As illustrated, the electronics unit 100 and printing module or unit 101 are nested together with the electronics unit 100 being carried by the printing unit 101 and the electronics unit fitting into a spatial envelope defined by the exterior dimensions of the printing unit. The plug and socket connectors (not shown) will, of course, be concealed when the two units 100 and 101 are nested together. The relatively light electronics unit which, as shown, is generally in the form of an electronic calculator, can then be disengaged from the rest of the machine, and taken separately to a Post Office, for recordal of the tote value and entry of further credit. In this event credit and tote values would, if necessary, be transferred to a non volatile backing store. For the printing module there should preferably be provided interlock means whereby, when the electronics unit is detached therefrom, operation of the printing module is prevented, thereby removing the possibility of unauthorised and unrecorded use. The electronics unit has an aperture, normally closed by a cover bearing a Post Office seal, providing for access to means for re-writing the credit and tote values. The mechanical arrangement of these means and the said cover is such that the latter cannot be securely closed unless the rewriting means are deactuated. The rewriting means may comprise a single key operable to cause an amount keyed on the normal keyboard of the machine to be fed into the credit register. The unit has interlock means such that when a new credit value has been set into the input register, it will not enter the credit register if too large an amount is already present there. This will prevent overloading.

As a mains power supply may not be available at a Post Office counter to which the machine or separate unit is taken for recordal, the machine may have a switch or key for causing the display means (which normally would consume a relatively large amount of energy) to be powered from a battery. This switch or key may be lockable and/or sealable in an "off" condition, the arrangement being such that the switch or key cannot be locked in the "on" condition (causing the battery to power the display means). Alternatively, or in addition, the machine may incorporate time delay means to disconnect the battery from the display means after a short period, say 5 seconds.

It is possible that, at the Post Office, the detachable unit could be powered from mains supply by means of a plug in power adaptor such that when the adaptor is plugged in the battery will be automatically switched off.

The machine part having the printing module may include a feed for feeding items to be franked, such as envelopes or labels, which feed preferably uses only solenoid actuators to transport such items.

Also, there may be provided in the machine part having the printing module a further register for storing tote information over the whole lifetime of the machine. This register could be electromechanical or mechanical.

As mentioned above, with reference to FIG. 5, it is possible to provide, in an embodiment of the present invention, means whereby upon occurrence of a fault, or upon attempt of a non-permissible operation, an indication is given, on a display, of the nature of the fault which has occurred or the reason for an operation being impermissible. For example, as indicated in FIG. 5, single letter diagnostic fault codes are displayed in a portion of a display. By way of example the following code letters, indicative of faults, as set out in table 3 hereinbelow may be given.

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)
______________________________________

It will be appreciated that, in any given embodiment of the present invention only the appropriate error codes will be provided. For example, in a machine having a non-volatile store as shown in FIG. 4, error code E need not be present.

Error code L indicates that a value selected to be franked is less than credit remaining in the machine, in which case franking is prevented. The machine may then lock off entirely or alternatively the franking of an appropriate lower value may be permitted. Of course, if no credit register is provided this code is not necessary.

Code letter H indicates that a present maximum value for the tote register will be exceeded if the selected desired value is franked. The machine may lock off completely or permit franking of a lower value.

FIG. 9 illustrates schematically an embodiment of the present invention which employs non-volatile working registers, or effectively non-volatile working registers employing a volatile store with a back-up battery. As is indicated in FIG. 9 the working registers may be modularly replaceable so that either a true non-volatile store or an effectively non-volatile store are alternatively employable in one machine.

The machine of FIG. 9 also includes mail counter 998 which comprises registers for storing information relating to different classes of mail franked as mentioned hereinbefore with reference to the keyboard of Table 2. The mail counter 998 thus comprises a first class mail counter 981, a second class mail counter 982, a label counter 983, and a counter 984 for the total number of items of mail franked.

The contents of any one of counters 981 to 984 may be displayed on display 994 by actuation of appropriate keys on keyboard 993. The embodiment of FIG. 9 further includes a printer 995, a control 997 and arithmetic unit 996 which may of similar construction to the corresponding items in FIG. 1. In FIG. 9, control links between control 997 and other items are indicated by broken lines. In the embodiment of FIG. 9 working registers comprise an input register 992 and credit and tote registers 991 or 990, which latter may be modularly interchangeable. The non-volatile credit/tote meter 991 may comprise an MNOS memory as mentioned above, whilst the unit 990 may comprise a CMOS memory, backed by a battery.

If an MNOS unit is employed then either mains supply via a power adaptor is required to drive the unit, or a high voltage battery supply (e.g. -30 V) is necessary.

The machine schematically illustrated in FIG. 9 is structurally divided into two separable units as shown in FIG. 10.

FIGS. 7A, 7B and 7C illustrate an operational algorithm for a machine as described with reference to FIGS. 1 and 3 for example.

FIGS. 8A, 8B and 8C illustrate an operational algorithm, somewhat simplified as compared with that of FIGS. 7, for a machine as described with reference to FIG. 9. The algorithm corresponds generally to the use of a configuration as shown in FIG. 4 in an embodiment of the present invention.

The following table provides a key for assistance in understanding the algorithms of FIGS. 7 and 8.

TABLE 3
______________________________________
##STR2##        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.

The algorithm of FIGS. 8A, 8B and 8C will now be described in detail.

In the algorithm of FIGS. 8 (and in that of FIGS. 7) solid-lined symbols indicate operational processes or decisions carried out or made automatically, whilst broken-lined symbols indicate manually actuated or effected processes or decisions.

It will be recalled that the algorithm of FIG. 8 applies to an embodiment of the present invention in which non-volatile working register are used (and hence no backing register is employed), which embodiment has, in addition to input and total registers, a credit register and also facilities for counting different classes of mail.

In the algorithm rectangular blocks indicate operational processes carried out, whilst diamond-shaped blocks indicate decision making.

Assuming that the machine has been started and that power supply thereto is on (blocks 81 and 82), the display of the machine is actuated as indicated at block 83. The display would normally indicate IR, that is, the current content of the input register fed in as a value to be franked, which at this stage of operation is zero since no value has yet been input. However, by appropriate operation of keys on the keyboard of the machine any of the following items may be displayed; FCC, the current count of first class items of mail; SCC, the current count of second class items of mail; LC, the current count of labels; TC, the total count of items of mail; CR, the content of the credit register, and TR, the content of the total register.

Next, as indicated at 84, a value to be franked is selected manually on the keyboard and is entered into the input register, and displayed. Then, at step 85 a decision is made as to whether or not a Post Office security switch of the machine is on. Assuming for the time being that this switch is on, in the next step a decision is made, block 86, as to whether or not a first class postage value (81/2p say) has been selected as a franking value. If this is found to be the case the first class mail counter of the machine is enabled for operation (block 87). It is found that a first class postage value has not been selected a decision is then made as to whether or not a second class postage value (61/2p say) has been selected as a franking value (block 88). If a second class value has been selected the second class mail counter of the machine is enabled for operation (block 89). After enabling of either the first or second class mail counters, or if it is found that neither a first nor a second class value has been selected, it is determined whether franking of a label has been selected (as opposed to franking of an envelope directly), for example by manual actuation of a label selecting switch on the keyboard, at block 90. If label franking is selected a label counter of the machine is enabled for operation (block 91). Subsequently, either after label counter enabling or after block 91 has been bypassed (label franking not selected) it is determined whether or not a high value has been selected for franking (block 92). If it is found that a high value has been selected the display of the selected franking value is caused to operate intermittently (block 93), thereby to attract the machine users attention, and a high value key of the machine is then, to enable further machine operation, set, as indicated at block 94.

Thereafter, or, if it is found that high value is not selected, directly after such non-selection is indicated, a franking key of the machine can be manually (or possibly automatically) actuated (block 95). The franking key is then disenabled, so that inadvertent repeat franking cannot take place (block 96).

It is then determined whether or not the credit register holds a value which is at least equal to the value held in the input register (block 97). If this is not the case a fault code letter "L" is displayed on the display of the machine (block 98). If the credit register is found to hold a sufficiently large value at step 97 the printer of the machine is operated in order to set it in accordance with the content of the input register (block 99). It is then checked that the printer is correctly set by means printing device monitoring means; if this if found not to be the case then until a period of five seconds has elapsed from the start of operation of the printer the printer continues to be driven and further checks made. If, at the end of the said 5 seconds it is found that the printer is still not set to the required value (blocks 180 and 181) the printer device is disenabled and a fault code letter "P" is displayed as indicated at steps 182 and 183.

Assuming, however, that a step 180 it is found that the printer is correctly set then the content of the input register is added to the content of the total register and subtracted from the content of the credit register (blocks 184 and 185).

It is then determined whether the content of the total register has exceeded a predetermined value. If this is found to be the case a fault code letter H is displayed and the content of the input register is deducted from the content of the total register and added to the content of the credit register (blocks 187 and 188). Thereafter operations may, for example, be recommenced for example using a lower franking value such as will not cause overflow of the total register.

Assuming, however, that overflow of the total register is not caused, it is then determined which, if either, of the first and second class mail counters has been enabled and that counter which has been enabled, if either, has its content counted up by one (blocks 189 to 192). It is then determined whether or not the label counter has been enabled, at step 193. If the label counter is found to have been enabled it has its content counted up by one (block 194). Thereafter, whether or not such counting up of the label counter takes place the total counter has its content counted up by one in step 195, whereafter printing or franking is effected on the item to be franked, which is thereafter ejected (blocks 196 and 197).

Franking of one item now being complete it is again determined whether or not a high franking value was selected (block 198). If it is found that a high value was selected the high value key is reset for further use as shown at step 199. Therefter the franking key is re-enabled so that further franking operations may be carried out (block 280). The user then decides whether or not it is required to frank further items at the previously set franking value (i.e. whether or not a multiple run at that franking value is required), as shown at step 281. if a multiple run is required then as indicated by B a further franking operation is undertaken from step 92 of the algorithm.

If a multiple run is not required then the user indicates whether or not further franking at a new franking value is currently required (block 282). If no further franking is required currently machine operations are stopped by the user actuating an "off" key for example (block 283). If a further franking operation is required, the input register is cleared and FCC or SCC and/or LC are disabled (block 284) whereafter operation may be recommenced from step 83 of the algorithm as indicated by C.

Now, returning to step 85 of the alogithm, if it is found that the Post Office security switch is off the following operations are effected.

When the Post Office security switch is off normal operations of the machine are suspended and the machine is in a condition for modification or value adjustment of values stored in its credit and total registers, by authorised Post Office personnel for example.

To this end the authorised Post Office employee must key in, via the keyboard, a secret code by which the machine recognises that person's authorisation by means of value adjustment enabling means provided in the machine, as indicated at step 285. It may also be necessary as mentioned hereinbefore to break a seal and open a combination lock prior to such entry of the secret code.

The secret code entered, it is determined whether or not it is in fact correct (block 286). If the code is found to be incorrect modification of credit and tote registers is disenabled.

Assuming, however, that the entered code is correct modification is then enabled (block 288) by the value adjustment enabling means. Thereafter, for example by operation of keys on the keyboard, modification values for the credit and/or tote registers are fed in and these values accordingly employed for such modification (step 289). If further modification is required then this can also be effected (step 290).

After completion of modification the user switches on the Post Office security switch (block 291) and thereafter the secret code is reset (step 292) whereafter if further modification is required the secret code must be keyed in once more. Now, if franking operations are then required, machine operation can be re-commenced from step ⁸ 3 of the algorithm but if no franking is currently required the machine can be switched to an off state.

It will be seen that the algorithm of FIGS. 7 is in may ways similar to that of FIGS. 8. However, the embodiment of the present invention to which the algorithm of FIGS. 7 refers has features as shown in FIG. 3, for example. That is to say, whereas the machine referred to in FIGS. 8 has non-volatile working registers (or effectively non-volatile working registers) the machine of FIGS. 7 has volatile working registers and non-volatile backing store. The machine also has, as hereinbefore described, a battery for ensuring correct transfer of information to the backing registers in the even of mains failure, or for powering the detacheable electronics unit of the machine (c.f. FIG. 10) when it is, for example, removed from the printer unit of modification machine for delivery to the Post Office for modiciation of credit and tote values therein.

It will be seen also that the algorithm of FIG. 7 explicitly takes into account the detachability of the electronics unit, whereas the algorithm of FIGS. 8 does not. However, it should be appreciated that a machine embodying the present invention and operating on the basis of the algorithm of FIGS. 8 does in fact have mutually separable electronics and printing units as hereinbefore described.

The machine described with reference to FIGS. 7 has facilities for providing counts of first and second class mail and of label franking and a total mail count, as does the machine of FIGS. 8.

The main differences between the algorithms of FIGS. 7 and 8 can be described as follows.

In FIG. 7B it will be seen that after is is determined whether the content of the credit register is at least equal to the content of the input register (or value register), corresponding to step 97 of FIGS. 8, and prior to driving of the printer (set printer, step 99 in FIGS. 8) the content of the input register IR is added to the content of the tote register and then it is determined whether or not the result will cause an overflow in the tote register (as in FIG. 8, step 186).

However, it is also determined whether of not the result is greater than or equal to a pre-programmed number N. If either overflow is found or the result is at least equal to N, fault code letter H is displayed and the machine locks off.

Thus, whereas in the machine of FIGS. 8 the maximum permitted value for the content of the tote register is simply the maximum possible value it can hold, in the machine of FIGS. 7 a lower maximum permitted value (N) can be set.

Following these steps, in FIG. 7, operation similar to that of FIG. 8 is resumed (except of course steps 186 to 188 of FIG. 8 have already been effected).

It will be seen also in FIG. 7 that if it is found, at a step corresponding to step 282 of FIG. 8, that no further franking is currently required, idle-state monitoring means in the machine operate to bring about transfer of the contents of CR and TR automatically to the non-volatile backing store upon elapsed of a predetermined period of time since completion of the last preceding franking operation.

It will also be noted that in the algorithm of FIG. 7 (c.f. FIG. 7A) if it is determined, in a step corresponding to step 82 of FIG. 8, that mains is off it is subsequently determined whether or not the detacheable electronics unit is detached from the printer unit. If the electronics unit is found to be detached it is then determined whether or not the battery voltage is sufficiently high. If not, an error code letter E is displayed intermittently, but if the voltage is found to be sufficiently high the display, for the content of the input register for example, is actuated.

Operations in relation to the Post Office security switch are also somewhat different in the algorithm of FIGS. 7, in that the normal operation step 85 of FIGS. 8 does not occur. A step equivalent to 85 of FIGS. 8 occurs in FIGS. 7 only if the electronics unit is found to be detached (for example for taking to the post office for modification of credit and tote values) and the battery voltage is found to be sufficiently high. It will be seen that succeeding steps in FIGS. 7 are similar to steps 285 to 292 of FIGS. 8, but before normal franking can be resumed the detacheable head must be replaced of course.

Further, different, operational algorithms are also possible of course in different embodiments of the present invention.

Claims

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. said electronics and printing units nesting together with the electronics unit being carried by the printing unit and with the electronics unit fitting into a spatial envelope defined by the exterior dimensions of the printing unit, the electronics unit being readily separable from the printing unit and the electronics and printing units being connected together by means of a plug projecting from one said unit which directly engages a socket in the other said unit to set up operative electrical connections therebetween when the electronics unit is engaged with the printing unit, said plug and socket connectors being concealed when said electronics and printing units are nested together.

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 energizing 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 and 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 keyboard 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.