Patent Publication Number: US-6212505-B1

Title: Postage meter with removable print head and means to check that print head is authorized

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to postage meters in which a print head utilized for printing postage indicia is removably mounted on the postage meter. 
     Postage meters include electronic means for carrying out accounting functions in respect of postage values which it is desired to apply to mail items by operation of a printer. The electronic means also carries out control functions for operation of the postage meter including operation of the printer. The accounting and control is carried out in a secure manner by housing the electronic means in a secure housing in order to protect the integrity of accounting data generated by the accounting means and to prevent fraudulent operation of the postage meter. It will be appreciated that it is also necessary, or at least desirable, to ensure that the printer cannot be operated to print postage indicia in respect of values for which proper accounting has not been effected. Accordingly the printer is usually housed, together with the electronic means, in the secure housing. 
     Previously postage meters have been provided with a drum printer or a thermal transfer printer for printing the postage indicia. With the drum printer, ink for printing the postage indicia is supplied by means of a replaceable absorbent roller containing liquid ink which rolls in contact with print dies on the print drum. With thermal transfer printers, ink is supplied as a layer on a replaceable ribbon which is fed past a thermal print head for transfer of ink to the mail items. Both the ink roller and the ink ribbon are removable from the postage meter by a user of the postage meter for replacement by a new ink roller or ink ribbon respectively. With both of these types of printer, the printer per se is maintained secure by the secure housing. In the case of the drum printer, mechanical elements for setting the printing elements of the printer are not accessible by a user of the postage meter and in the case of a thermal transfer printer, electrical connections to the print head for control and operation of the print head are protected from access thereto. 
     It is now proposed, instead of drum printers or thermal transfer printers, to use ink jet printing devices. Ink jet print heads are already used widely as computer output printers where security of operation thereof is neither a problem nor required. The ink jet print heads manufactured and sold for use in computer output printers comprise a module including a row of ink jet nozzles and means for ejecting selectively ink from those nozzles. The module also includes electronic circuits for operation of the ink ejection means and an ink supply to supply ink to the nozzles to replenish ink ejected from the nozzles in printing. When the ink in the ink supply is exhausted the entire module including the nozzles and electronic circuits is removed and replaced by a new ink jet print head module. It will be appreciated that the module is provided with electrical connections which, when the print head module is mounted in the postage meter, interface with similar connections of the postage meter. 
     SUMMARY OF THE INVENTION 
     According to the invention a postage meter includes a printing device removable by a user of the postage meter; electrical connection means interfacing with electrical contacts on the printing device when the printing device is mounted in the postage meter; said printing device including identification means storing a unique identification of the printing device; said postage meter including reading means to read the unique identification from the identification means and to determine from the unique identification whether the printing device is authorized for use in the postage meter and said postage meter being operable to print postage indicia only if the printing device is authorized for use in the postage meter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     An embodiment of the invention will be described hereinafter by way of example with reference to the drawings in which: 
     FIG. 1 is a block circuit diagram of a postage meter, and 
     FIG. 2 illustrates a removable ink jet print head module. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1 of the drawings, the postage meter includes electronic accounting and control means comprising a micro-processor  10  operating under program routines stored in a read only memory (ROM)  11 . A keyboard  12  is provided for input of commands and data by a user and a display  13  is provided to enable display of information to the user. A random access memory (RAM)  14  is provided for use as a working store for storage of temporary data during operation of the postage meter. 
     Non-volatile duplicated memories  15 ,  16  are provided for the storage of critical data relating to use of the postage meter and which is required to be retained even when the postage meter is not powered. The microprocessor  10  carries out accounting functions in relation to use of the postage meter for franking mail items with amounts of postage charges applicable to handling of the mail items by the postal authority or another carrier. Accounting data relating to use of the postage meter for printing franking indicia representing postage charges for mail items and any other critical data to be retained is stored in the non-volatile memories  15 ,  16 . The accounting data includes a value of credit, an accumulated total of value used by the meter in franking mail items, a count of the number of mail items franked by the meter and a count of the number of mail items franked with a postage charge in excess of a predetermined value. The value of credit may be a value of credit available for use by the meter and stored in a descending credit register. The accumulated total value used by the meter is stored in an ascending tote register, the count of items is stored in a piece count register and the count of items franked with a postage charge in excess of a predetermined value is stored in a large items register. Alternatively, if desired, instead of a descending register storing a value of credit available for use by the meter, a total value of credit entered into the meter may be stored in an ascending credit register. 
     As is well known in the postage meter art, each of the registers referred to hereinbefore for storing accounting data is replicated in order to enable integrity of the accounting data to be maintained even in the event of a fault or termination of power to the meter during a franking operation. Two replications of each of the registers are provided in each of the memory devices  15 ,  16 . 
     A motor controller  17  is controlled by the microprocessor  10  to control operation of motors  18  driving feeding means (not shown) for feeding a mail item past a stationary digital print head  19  or for moving the digital print head in a translational movement relative to a print receiving area of a stationary mail item. The digital print head  19  is a removable print head connected to the postage meter by means of a connector  20 . The digital print head is preferably an ink jet print head constructed as a module  21  as shown in FIG.  2 . The module is provided with a plurality of electrically conductive pads  22  which interface with conductive elements of the connector  20  when the module  21  is mounted in the postage meter. The ink jet print head includes a plurality of ink ejection nozzles (not shown) from which ink may be ejected selectively by means of the operation of electronic circuits in the module. The module also contains a supply of ink to replenish ink ejected from the nozzles. 
     Sensors  30  are provided to sense and monitor feeding of the mail item, if the print head is stationary, or to sense and monitor motion of the print head, if the mail item is stationary. The sensors provide signals to the microprocessor to enable the microprocessor to control feeding of the mail item or motion of the print head and to output signals on bus  24  to selectively operate the circuits in the print head module to eject ink droplets from the nozzles at appropriate times as the mail item is fed past the nozzles of the print head. 
     Electrical power is supplied to the electronic circuits of the postage meter including the microprocessor, the print head module and the motor control from a power source  25 . 
     It will be appreciated, as is well known in the postage meter art, that the postage meter must operate in a secure manner and be protected from attempts to use the meter fraudulently for example by utilizing the postage meter to print franking indicia on mail items for which no corresponding postage charge has been accounted for by the accounting means. Accordingly those parts of the postage meter required to be secured against unauthorized tampering are housed in a secure housing  26 . 
     In so-called prepayment operation of a postage meter, each time a franking operation is to be performed, the microprocessor carries out a routine in which a determination is made as to whether the value of credit in the credit register in NVMs  15 ,  16  is sufficient to permit the franking operation in respect of the required postage charge for a mail item to be performed. If the value of credit in the credit register is sufficient, the franking operation is continued and the accounting data in the registers is updated to account for the postage charge and the franking indicia is printed. However if the value of credit in the credit register is not sufficient to permit the franking operation in respect of the required postage charge to be performed, the operation is terminated and the franking indicia is not printed. Where a value of credit available for use in franking is stored in a descending register, the check as to sufficiency of the credit available is effected by a determination of whether the postage charge is less than the credit value. Where a total value of credit is stored in an ascending credit register the check as to sufficiency of credit is effected by a determination of whether the total value of credit is at least equal to the sum of the postage amount and the accumulated total value in the tote register. 
     As described hereinbefore, the print head module  21  includes an ink supply. Accordingly when the ink supply is exhausted the module  21  must be removed and replaced by a new module containing a full ink supply. Removal of the used module and replacement by a new module needs to be effected by a user of the postage whenever the ink supply becomes exhausted. It is desirable that measures are taken to ensure that only authorized print head modules are mounted in the postage meter. Accordingly the print head module is provided with means uniquely identifying the print head module. Conveniently the means uniquely identifying the print head module may be a smart semiconductor device  23  secured to the module. The smart device  23  is so located on the module that, when the module is mounted operationally in the postage meter such that the contact pads  22  of the module interface with the connection elements of the connector  20 , the smart device is in communication with a sensor port  27  connected to the microprocessor  10 . In a postage indicium printing routine, the microprocessor reads data recorded in the smart device and, if the unique identity of the print head module read from the smart device is recognized by the microprocessor of the postage meter, the microprocessor continues with the postage indicium printing routine. If desired the unique identity read from the smart device may be included in the printed postage indicium or other information read from the smart device may be printed as a part of the postage indicium. The information stored in the smart device may include date of issue of the print head module, an expiration date after which the print head module is not to be used and the serial number of the postage meter in which the print head module is to be used. All or part of this information may be included in the postage indicium. In addition the postage meter may store in a register in the non-volatile memories  15 ,  16  a count of the number of postage indicia printed using the currently installed print head module. This count may also be included in the printed postage indicium. If desired and if the smart device can be written to by the microprocessor  10 , the microprocessor may write the count of postage indicia to the smart device instead of or in addition to storing the count in the non-volatile memories  15 ,  16 . The information may be stored in the smart device in encrypted form or the information may be stored in non-encrypted form but be encrypted by the microprocessor  10  prior to printing the information in the postage indicium. 
     The postage meter may include a real time clock  31  whereby the microprocessor may determine from date information read from the smart device  23  whether the current date is within a period in which the printing device is authorized to be used. If the current date is not within the period of authorized use of the print head, the microprocessor may inhibit further printing of postage indicia with the installed printing device thereby requiring the user to replace the printing device with a printing device having an acceptable date range. 
     As described hereinbefore, the microprocessor reads the unique identification information from the smart device during a postage printing routine. If desired the identification may be read in each postage printing routine or may be read at each power up of the postage meter. However if the identification is read only upon power up of the postage means it would be necessary to provide an indication to the microprocessor whenever a print head module is removed from and a print head module is installed in the postage meter and to cause the microprocessor to read the identification from the currently installed module prior to further printing of postage indicia. 
     To prevent removal of the smart device from the print head module with the intention of using the smart device in conjunction with an unauthorized print head module, the smart device may be formed on a relatively fragile substrate and secured to the module in such a manner that any attempt to interfere with or remove the smart device would result in destruction of the smart device. 
     The information, including the unique identity of the print head module, is recorded on the smart device prior to distribution of the print head module from a supply depot. The unique identity may include or comprise a unique identification applied to the postage meter with which the module is unauthorized to be used. The postage meter may utilize information read from the smart device to determine the number of postage indicia printed by the print head module and to inhibit printing utilizing that module when a predetermined number of indicia have been printed. Also the postage meter may utilize information read from the smart device to inhibit use of the module after a predetermined date. 
     The smart device  23  may be of a type having electrical connections in which case the port  26  includes electrical connections to interface with the connections of the smart device. Alternatively the smart device may be of a noncontact type in which case the port  26  is constructed to communicate with the smart device in a non-contact manner by electromagnetic radiation or the like appropriate to the smart device. 
     If desired access to the print head for removal and replacement thereof may be controlled in a secure manner, for example, as described in co-pending U.S. patent application Ser. No. 09/070,023 filed by Cyrus Abumehdi on the same date as the present application and claiming priority from GB patent application 9709051.8. The content of said co-pending U.S. patent application is hereby incorporated herein.