Franking machine

Abstract

 A franking machine is disclosed in which accounting data is optically recorded on a tape (19) housed in a removable cassette (50). For each franking operation updated accounting data is recorded and thereby the recorded tape provides an audit trail for a sequence of franking operations. Prior to franking, the recorded data is read and checked for validity. The recording is effected by a laser beam traversed across the tape either by mechanical movement of the laser source (15) or by an optical deflection system (54, 56). The tape is stepped after each recording or the laser beam may be stepped along the tape. Sensor means (22, 53) are provided to inhibit operation if the cassette (50) is not in position or if there is no tape (19).

Description

[0001] This invention relates to franking machines for franking items of mail and in particular to such machines in which an accounting record is maintained relating to the value of franking printed by the machine.

[0002] Franking machines are provided with means such as an electronic microprocessor for carrying out accounting functions to generate accounting data to maintain an accurate record of usage of the machine for printing franking on mail items. Franking machines may either operate in a pre-payment mode or in a post payment mode. In the former mode, the machine is provided with a credit register to store a value of credit available for use in a series of franking operations, the stored credit value being decremented by the amount of franking printed each time an item is franked. In addition, the machine is provided with a tote register to store the accumulated value of franking printed by the machine and an items count register to store the number of items franked by the machine. Periodically, as the value of credit stored in the credit register decreases to a low value, additional credit is purchased by the user from the postal authority and this value of additional credit is added to the value stored in the credit register. When the credit available has reduced to a low value, for example zero, the machine is caused to lock and prevent further usage until credit has been entered into the credit register. In machines to be used in a post payment mode, the credit register may be dispensed with or, as may be more convenient, the machine is programmed such that it does not lock when their is no value of credit in the credit register. Periodically the postal authority reads the registers of the machine in order to carry out an audit on the operation of the machine and to check that the account data stored in the machine tallies with the account data for that machine held by the postal authority. Such reading of the registers is conveniently effected when additional credit is entered into the machine.

[0003] It will be appreciated that the accounting for credit and postage value used provides the basis upon which the user pays for franking of mail items and for which the postal authority receives payment for handling of those mail items. Accordingly it is essential that the registers maintain an accurate record of account which is not lost or corrupted due to mal-function of the machine or by attempts to tamper with the machine. The registers are required to be non-volatile so that the accounting data stored therein is not lost when supply of electrical power to the machine is terminated either due to interruption of the mains supply or due to switching off the machine. In order to protect against loss or corruption of the stored data, two independent memory devices are provided and each register is duplicated in each memory device. In each operation of the machine, the contents of the duplicated registers are compared and franking is permitted only if this comparison is successful. If the comparison fails, further operation of the machine is inhibited and it is necessary, prior to further use of the machine, for the contents of the registers of the machine to be read out by a service technician. Generally after a mal-function of the machine this enables the account records to be retrieved. However if a catastrophic failure should occur, information may be lost from most or all of the replications of the registers and after such an occurrence it would not be possible to determine the values stored by the registers immediately prior to the failure. As a result there would be no record of usage of the machine after the last preceding reading of the register values, for example at the last credit update.

[0004] It is desirable that the accounting records should be stored in a substantially non-destructible manner in respect of each operation of the machine. This would provide a substantially permanent record which would enable inspection at any time of the records relating to all previous operations of the machine and would enable retrieval of the records of account up to that relating to the last item franked prior to the occurrence of a catastrophic failure.

[0005] According to the invention a franking machine includes means operative to generate data relating to usage of the machine and recording means; said recording means including a laser source operable to generate a laser beam; means to expose portions of a recording medium sensitive to exposure to a laser beam to be acted upon by the laser beam generated by said source; and means responsive to said data generation means to operate the laser source in a manner indicative of said data thereby to record data relating to usage of the machine on the recording medium.

[0006] An embodiment of the invention will now be described with reference to the drawings in which:-
Figure 1 is a block circuit diagram of a franking machine incorporating means for non-destructive storage of accounting records,
Figure 2 illustrates a recording mechanism for the storage of accounting records,
Figure 3 illustrates data recorded on a recording medium and reading means for reading the recorded data,
Figure 4 is a flow chart of the operation of the franking machine,
Figure 5 illustrates bi-directional scanning of the recording medium,
Figure 6 illustrates single directional scanning of the recording medium, and
Figure 7 illustrates a recording mechanism similar to that of Figure 2 for recording on two recording media.

[0007] Referring first to Figure 1, a franking machine is provided with a microprocessor 10 which is programmed to carry out accounting and control functions required in the franking machine. Sequences of program steps for these functions are stored in a read only memory (ROM) 11 connected to a bus 12 communicating with the microprocessor. A working memory 13 in the form of a random access memory (RAM) is connected to the bus 12 for the storage of data required during the carrying out of a program sequence. A keyboard 45 and a display 46 are connected to the bus 12 for the input of data and command signals by a user and for the display of data and other information to the user respectively. Printing means 47 for the printing of a franking impression on mail items is controlled by microprocessor 10 to print franking impressions of desired postage values in accordance with input of data and command signals on the keyboard, or otherwise, by the user. The provision of keyboard, display and printing means controlled by a microprocessor in a franking machine is well known and accordingly it is believed to be unnecessary to describe the operation thereof in detail.

[0008] A recording device for the non-destructible storage of accounting data is connected to the microprocessor 10 by means of an input/output interface 14. A laser diode 15 is powered from a power source 16 under the control of a modulator 17. The modulator 17 is driven by signals on line 18 from the interface 14. A recording tape 19 is fed past the laser diode 15 by means of a geared drive from a stepper motor 20 from a supply spool 21 (see Figure 2) onto a take up spool 22. Energisation of the motor 20 is effected by motor drive 23 controlled by signals on line 24 from the microprocessor 10 via the interface 14. An incremental encoder 25 mechanically coupled to the drive to the tape provides feedback signals on line 26 to the microprocessor 10 via the interface 14 to enable precise control of the feeding of the tape 19. Data is written onto the tape transversely of the tape and to enable this to be effected the laser diode 15 is mounted on a carriage 27 which is slidable on a guide bar 28 transversely relative to the tape and is caused to traverse the width of the tape by means of a lead screw 29 driven by means of a geared drive from a stepper motor 30. The motor 30 is energised by a driver 31 under the control of signals on line 32 from microprocessor 10 via the interface 14. An incremental encoder 33 is mechanically coupled to the traversal drive of the laser diode carriage 27 to provide feedback signals on line 34 to the microprocessor 10 via the interface 14. A collimating optical system 35 is provided between the laser diode 15 and the recording tape 19.

[0009] Referring now to Figure 3, the tape 19 comprises a strip of flexible optical recording material upon which data may be recorded optically by exposing the material to the action of a laser source. One example of such material comprises a base layer 36 of synthetic plastics material, for example a polyester, carrying a metal layer 37 covered by a layer of dye polymer 38. A protective layer of transparent material 42 extends over the layer 38. A recording material of this form has been developed by Imperial Chemical Industries and is known under the trade name Digital Paper. Writing of data on the material is effected by exposing the dye polymer layer 38 to the action of the laser source which has the effect of modifying the exposed portion of the dye polymer layer. Data may be read optically from the recording material by a reading head 39 comprising a source of illumination 40 to illuminate the dye polymer layer 38 and an optical sensing device 41 responsive to light reflected back from the metal layer 37 in the material. Prior to exposure to a laser source the dye polymer layer is substantially opaque so that no light is reflected from the metal layer. After exposure the dye polymer becomes highly transparent so that light is reflected by the metal layer. Thus if data bits of one value, for example binary '1' cause operation of the laser diode 15, data bits of value binary '1' result in the dye polymer layer being modified and are recorded as transparent areas in the dye polymer layer. Data bits of the other value, for example binary '0' do not cause energisation of the laser diode and hence do not cause modification of the dye polymer layer and are recorded as opaque areas in the dye polymer. Alternatively if desired the laser diode may be energised to record binary '0' and de-energised to record binary '1'. After each traverse of the laser diode, the stepper motor drive 20 is energised to feed the tape incrementally to bring an unexposed portion of the tape into a position for recording upon by the laser diode. The franking machine is provided with the reading head 39 and this may be mounted on the carriage 27 so as to traverse the tape when the motor drive 30 is energised. The source of illumination may comprise the laser diode 15 energised at a sufficiently low level as to ensure that the dye polymer of the tape is not modified. When required, clock signals may be generated from the output of the incremental encoder for strobing the output of the sensing device.

[0010] Recording material as hereinbefore described is of low cost, has a very high recording density and the data recorded thereon is substantially indestructible. Use of such recording material for accounting data storage permits a very much larger quantity of data to be stored as compared with conventional semi-conductor memories used in franking machines. Furthermore optical recording material has a high immunity to corruption of data and does not require the battery backup needed for many semi-conductor storage devices.

[0011] When the franking machine is put into service initial accounting data is written onto the tape. Operation of the franking machine in carrying out a franking of a mail item together with the accounting and recording of the updated account data is illustrated by the flow chart of Figure 4 to which reference is now made. When a franking operation is initiated by a user, the microprocessor reads the accounting data from the tape to determine that the requested franking is valid and within the limit of credit available. If the franking is permitted, the microprocessor modifies the data to take account of the current franking operation and writes the modified data to the tape. The data written to the tape comprises the value of credit available for franking, accumulated postage value used in franking, a count of the number of items franked after completion of the current franking operation. The data written to the tape may also include the postage value used in the current franking operation and any other information required to be retained as a record.

[0012] It will be appreciated that the data recorded on the tape comprises a detailed account updated for each franking operation. Accordingly it is not necessary to provide the usual non-volatile semi-conductor memories for storing accounting data. However if desired the random access memory 13 may include registers to retain current account record values in which case, when a franking operation is initiated by a user, the microprocessor reads these values, modifies the values in accordance with the current franking operation and then writes the new values in the registers and also writes the new values to the tape to form the permanent record of account. In this latter arrangement it is not necessary to read data from the tape and hence the reading head 39 could be omitted from the machine. However it is preferred to provide the reading head in order to be able to verify correct recording of the data and to enable the next printing cycle if the data has been correctly recorded.

[0013] The data written to the tape may include a check sum or it may be in the form of a hamming code with data bits and check bits for each character of information.

[0014] In order to ensure further integrity of the record data stored on the tape, the account data may be written to two tapes whereby integrity of the data can be confirmed by comparison between the data recorded on the two tapes. As shown in Figure 7 two tapes 19, 48 may be fed alongside one another by the motor drive 20 past the laser diode 15 and the carriage for the laser diode may be traversed such that the laser traverses both tapes. The data to be written in a single traverse of a tape may be held in a buffer which is read out twice in succession to energise the laser diode to write the same data on each tape successively in a single traverse of the two tapes. Alternatively two separate recording mechanisms may be provided, each mechanism operating independently and being driven in parallel by signals from the microprocessor.

[0015] Conveniently the accounting data resulting from the carrying out of a franking operation may be recorded on the tape or tapes in a single traverse of the laser diode and data resulting from successive franking operations would be recorded in successive traverses of the laser diode. Thus each line of recording across the tape would relate to a single franking operation.

[0016] As is well known in franking machines, the electronic circuits for carrying out accounting and control functions are contained in a secure housing to prevent unauthorised interference with the operation of the circuits. In the present construction of franking machine, the laser diode and the drive mechanisms are housed within a secure housing, indicated by line 49 (Figure 1) and the recording tape is housed within a module which may be contained within but can be removed from the secure housing. This module may be in the form of a cassette 50 in which the supply 21 and take up 22 reels are housed, means being provided to permit mechanical coupling between the geared stepper motor 20 and means for feeding the tape. The cassette would be provided with a suitable access aperture 51 to permit exposure of the tape to the laser beam from diode 15. Interlock means are provided to prevent operation of the franking machine whenever a module is not secured in operative relation to the secure housing. The interlock means includes a cassette sensor 52 and tape sensing means 53 is provided to sense that recording tape 19 is present for exposure and to prevent operation of the franking machine when the tape is not present. Such interlock and tape sensing means are constructed in such a manner as to prevent unauthorised interference therewith.

[0017] Equipment for reading and writing data may be provided for use by the postal authority to enable the authority to audit usage of the franking machine when the recording tape, in its cassette module, is returned to the postal authority by the user. The auditing may be carried out when the user, wishing to make a payment for postage credit, returns the tape for the new updated credit value to be recorded on the tape by the postal authority. Such equipment would comprise means for feeding the tape incrementally and for traversing the tape with a reading head 39. The equipment would include electronic circuitry responsive to the output of the reader head to display the recorded data and to control the drives to the tape feed and the traversing of the read head. The equipment would also include a recording head to enable the new updated credit value to be recorded.

[0018] While the use of a tape of optical recording material has been described for maintaining records of account in a franking machine it should be understood that such recording of records may be used in other machines in which it is required to maintain a substantially permanent indestructible record. Accordingly, the term franking machine is to be understood as not being limited to machines which print franking impressions and to include any other mailing apparatus associated with mail processing of letters, parcels, manifest and batch mailing in which a record of usage is required to be maintained. Also it should be appreciated that the optical recording material instead of being initially opaque and modifiable to be transparent may be initially transparent and modifiable to be opaque for the recording of data.

[0019] Instead of moving the laser diode 15 transversely of the tape to scan the laser beam across the tape, scanning means may be provided to scan the laser beam from a stationary laser diode as is shown in Figure 5. The laser beam is deflected by scanning means 54 to scan across the width of the tape 19 as the diode is energised to record data on the tape. The tape is maintained stationary and the scanning means 54 is arranged to deflect the laser beam so as to step successively along the length of the tape between consecutive scans of the laser beam across the tape. Depending upon the quantity of data to be recorded on the tape, the tape may be fed at intervals to bring an unrecorded portion into a position in which it can be scanned by the laser beam or the tape 19 may be provided as a relatively short length supported in a transparent cassette 55 such that all of the recording area of the tape can be scanned without movement of the tape. The tape may be supported so as to lie in a plane or if desired it may be supported to have a different configuration. For example it may be be curved so as to lie at a constant distance from the source of the deflected laser beam. Due to the density at which it is possible to record data on the recording medium, a relatively short length of tape would permit data relating to the use of the franking machine for a substantial number of franking operations to be recorded. Figure 6 illustrates a further modification in which the tape 19 is fed lengthwise as in Figure 2 but instead of mechanically moving the laser diode to traverse the width of the tape, the laser diode is stationary, as in Figure 5, and scanning means 56 deflects the laser beam to scan across the width of the tape.

Claims

1. A franking machine including means (10) operative to generate data relating to usage of the machine characterised by the provision of recording means (15, 19) including a laser source (15) operable to generate a laser beam; means (27, 29; 54; 56) to expose portions of a recording medium (19) sensitive to exposure to a laser beam to be acted upon by the laser beam generated by said source; and means (17) responsive to said data generation means (10) to operate the laser source (15) in a manner indicative of said data thereby to record data relating to usage of the machine on the recording medium (19).

2. A franking machine as claimed in claim 1 further characterised in that said recording medium (19) is in the form of a tape (19) and in which the franking machine includes feed means (20) to feed the tape past the laser source (15) from a supply of unexposed tape (21).

3. A franking machine as claimed in claim 1 or 2 further characterised by scanning means (27,29,30; 54; 56) operable to scan the laser beam transversely of the tape (19).

4. A franking machine as claimed in claim 3 further characterised in that the scanning means includes a carriage (27) supporting the laser source (15) and means (29, 30) operable to move the carriage transversely of the tape (19).

5. A franking machine as claimed in claim 3 further characterised in that the scanning means includes deflection means (54; 56) to deflect the laser beam transversely of the tape (19).

6. A franking machine as claimed in claim 5 wherein the scanning means includes deflection means (54) to deflect the laser beam both transversely and longitudinally of the tape (19).

7. A franking machine as claimed in claim 1 further characterised in that said recording medium (19) is supported to be stationary relative to the laser source (15) and the recording means includes deflection means (54) to deflect the laser beam in two mutually perpendicular directions across the medium (19).

8. A franking machine as claimed in claim 7 further characterised in that the recording medium (19) is supported in a cassette (50) transparent to the laser beam, said cassette being removable from the franking machine (49).

9. A franking machine as claimed in any preceding claim further characterised in that the recording medium has a first layer (38) and a second reflective layer (37); said first layer (38) having a first state of optical transparency prior to exposure to the laser beam and having a second state of optical transparency different from said first state of transparency after exposure to the laser beam, one state being substantially opaque and the other state being substantially transparent whereby light from illumination of the recording medium is reflected by said second layer at positions of the medium where the first layer is in the transparent state.

10. A franking machine as claimed in any preceding claim further characterised by means (15,39) operable to read data recorded on said recording medium (19); said reading means (15,39) comprising means (15) to illuminate the recording medium (19) and sensing means (39) responsive to light reflected by the medium.

11. A franking machine as claimed in any preceding claim further characterised by a secure housing (49) containing at least the data generation means (10) and the laser source (15) and a module (50) removably secured to the housing, the recording medium (19) being contained in said module (50).

Drawing