EP0944028B1 - Method for a franking and address printing machine - Google Patents

Description

The invention relates to a method for a franking and addressing machine according to the preamble of claim 1. The method is suitable for a closed system, in particular for users of franking machines.

Franking and addressing are so far mainly carried out by separate machines. The franking imprint, which is usually applied to the filled envelope, requires a special printing technique, which in turn is not suitable for address printing. For applications in which letter envelopes are both franked and addressed by machine, the use of two separately operating machines in the outbox processing is a considerable investment. Also require two machines corresponding footprint, as well as twice the maintenance.
Older franking machines print with a printing drum whose numerical wheels are previously set according to the post value to be printed, the setting being monitored by sensors. EP 194 662 B1 teaches an electronic postage meter having a status checker wherein a status of items of the postage meter machine is monitored by a microprocessor which, when interrupted, assembles a queue of tasks based on the status.

Newer franking machines use digitally working printing units. For example, applicant's metering machines T1000 and JetMail for the first time worldwide have a thermal transfer printer or an inkjet printer. This makes it possible in principle to print addresses on a filled letter, but only in the area of the franking stamp. The postal regulations of most countries rule out that the address information can be made at the level of the franking imprint. A print in the address area of the envelope for the mail recipient address is not possible with such machines, since the print width of the print head is not sufficient.

Another obstacle to the execution of franking and address printing with the same printing unit so far is the demand of the postal authorities for a special color for the franking imprint (usually orange) often coupled with the requirement for fluorescence. Franking imprints with such color have not been copied on conventional color copiers true to the original. So far there has been some protection against the copying of franking imprints. With advances made in color copiers and color printers, such a measure can no longer be considered a serious obstacle to producing counterfeit, unclaimed imprints.

On the other hand, with regard to the automatic letter distribution systems, there is a demand for a color that is as high in contrast as possible, especially for address printing, which should be able to be scanned automatically and with high security. Based on the scanned address data, the letter is controlled by the mail sorting facility of the mail distribution centers. However, the printing devices of conventional franking machines print their impressions only with the color post orange. The requirement of machine readability in combination with high processing speed is best met by the color black.

Digital franking machines of the type described above are not completely safe. Thus, future color copiers will be able to duplicate a franking imprint that is visually indistinguishable from an original imprint. The US Post has therefore made a list of demands with requirements for the construction of future franking machines (Information based Indicia Program IBIP) and published on 13.06.1996. It proposes cryptographically encrypting certain data and printing it in the form of a digital signature on the letter. Each impression differs from the other. The scanning of this information and its decryption allows the postal authority to recognize fake franking imprints. These requirements are differentiated according to the type of franking device. For standalone machines, an impression is proposed in which a particular set of franking data is included in the encryption. On the post office side, it would be necessary, after deciphering the impression, to make a comparison with all the previous impressions recorded in a database. According to estimates by fraud, the US Postal Authority has an annual damage of approximately US $ 200 million. If an identical impression is discovered, there is a forgery. The effort for a complete archiving of all imprints and the implementation of a comparison under real-time conditions would be enormous.

Traditional franking machines, which usually print only a franking stamp in red, are also referred to as "closed systems" and, unlike so-called "open systems" (PC frankers), do not need to include the corresponding letter address in the encryption. For "closed systems", however, a security module with advanced crypto technology and a secure housing is still required, in which data from the data center can be stored.

US 5,200,903 (EP 298 775) discloses a franking device which prints both the franking mark and the address. For small mail volumes, the expense of transporting letters relative to the stationary printhead is disadvantageous. Another shortcoming is that the printing of both images should be done in a single motion phase of the letter. This requires a printhead that is as wide as it corresponds to the widths of the two images franking stamp and address field and the intervening space. These are already 10 cm for a standard letter, for other letter formats up to 20 cm. Although a correspondingly wide thermal print head can be produced in principle, it would be disproportionately more expensive than a standard head of about 3-6 cm. As ink jet printhead such widths for the foreseeable future for manufacturing reasons (yield) are not executable. Also, it is not clear how the required for an ink jet printhead constant distance to uneven letter surfaces should be guaranteed.

In DE 196 05 015 a device for printing a standing on an edge print carrier is described in which in a guide plate two recesses are included, one for the franking and one for the address printing. The print head can be adjusted between both recesses. Even if the adjustment of the print head is initiated immediately after the first print image has been generated, a certain time elapses until the print head has assumed its second position. During this time, however, the letter moves on, so that only a very limited letter length is available for the second impression. Vertically overlapping printed images are generally excluded from this solution.

In US 4,868,757 a solution for the printing of postage stamp and address field is also disclosed with a printing unit. The letter is automatically fed into the printing station. After taking his Printing position, the print head is automatically lowered onto the letter surface until physical contact is established. The printhead is movably arranged in one direction to reach the entire print field. A disadvantage over the inventive solution is the expense of the automatic letter feeder. Also, the use of an ink jet printhead is excluded, because this requires a nearly constant distance of the printhead nozzles to the letter surface, even if the latter has considerable unevenness. In addition, the franking imprint is not forgery-proof.

In US 5,025,386, not only is a envelope transported in one direction, but a printhead is reciprocated in the same direction and opposite thereto to print a line within a window. To print another line, the printing device must be adjusted orthogonally.

An orthogonal adjustment of a printhead, without a constant reciprocating motion of the printhead is required for line printing, has been described in US 5,467,709. For printing itself, the print head remains in a first printing position, while the letter envelope is transported by means of a transport mechanism. However, a second printing position is only activated for alternative printing on franking strips. A printing of franking and addressing data on a letter envelope is not provided with such a franking machine. A disadvantage is the addition to the adjusting mechanism necessary letter transport mechanism, without which the printing would be impossible.

In US 5,611,630 the usual in commercial inkjet printers techniques, especially the shuttle principle for the reciprocating Duckkopfes in the X direction, were combined with a franking machine without letter transport mechanism. About an eccentrically positionable support rod can be a small stroke in the Y direction the print head are applied to print out a second printed field image with an offset of half a dot pitch. On the one hand, this technique is time-consuming in printing and, on the other hand, is not suitable for additionally printing in a second printing position further removed from the first one, for example a mailing address.

In DE 40 18 166 C2, a franking module for a personal computer has already been proposed for such users with low mail volume, in whose slot of a drive insert the franking module is arranged, which allows both the franking and the addressing of envelopes. Such a franking module is surrounded by a secured housing and, in terms of circuitry, has the same structure as a franking machine in which the letter transport device is saved. By using the franking module, the settlement of the franking and the printing of the franking stamp image can not be manipulated externally. The address data are read by a memory managed by the personal computer and fed to the franking module via the internal information network. Such a franking module is operable only in connection with the personal computer, but not suitable as a stand-alone machine. In addition, only standard curve fits in the feed slot. The printing mechanism itself has not been disclosed there. In a digital printing process, it is not safe to determine whether the printed postage stamp image is not merely an uncollapsed copy of an earlier impression and has been combined with a desired other address.

The object of the invention is to make a low-cost stand-alone machine for smaller mail volumes so that the functions franking and addressing of original mail are combined in one machine and allows the use of a cheap ink jet printhead. Both impressions should be made directly on the letter surface. The solution is also for filled letters with uneven surface a consistently good Ensure print quality. The operation of the machine should be controlled so that the processing time is minimized.

The security of the franking imprint against fraudulent manipulation should meet the future stringent requirements of the postal companies and at the same time allow a low-cost verification of the authenticity of each imprint.

The object is achieved with the features of claim 1.

According to the invention, a request for the input of a shipping destination address, a generation of the print image for the address field, starting the printing of the address and a control of the information processes for generating a security imprint takes place parallel to certain movement sequences of the printhead. The movements of the printhead include the procedures for printing the address and / or the positioning before printing. The information processes relate in particular to a generation of a digital signature. The latter is performed prior to the printing of the franking stamp image time-parallel to the first task of printing the address and corresponding movements of a print head, so that overall a time-optimal sequence is achieved when printing the address and the franking stamp image.

It is envisaged that during the period from the start to the completion of the printing of the dispatch destination address by a microprocessor further functions or JOBs will be processed in a time-interleaved manner, which prepare the printing of the franking stamp image.

• Fig. 1a und b, Flußplan für eine zeitoptimale Steuerung,
• Fig. 2, Frontansicht der Frankiermaschinendruckmechanik,
• Fig. 3, Beispiel für einen Abdruck auf einem Poststück.

Advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to FIGS. Show it:

• 1a and b, flow chart for a time-optimal control,
• 2, front view of the postage meter printing mechanism,
• Fig. 3, an example of an impression on a mail piece.

Figures 1a and b show a flow chart for a time-optimal control of a franking machine printing mechanism, which was shown in Figure 2 in principle as a front view. In a feed slot 1, a standing on the edge - not shown - - letter are inserted into a holding device 2. The holding device 2 is inclined at an angle α to the vertical and at an angle β to the horizontal. As an example of an impression on a mail piece, the imprint page of an envelope was shown in plan view in FIG. This letter shows a franking imprint in a franking field and a mailing address imprint in an address field. For addressing and franking this is inserted in the aforementioned feed slot rotated by 180 ° in the aforementioned feed slot 1. By the inclination 2 by the angle α and the guide plate 3 of the holding device 2 is inclined by the angle α to the vertical. Thus, the printing side is applied to the guide plate 3 when the letter comes with its edge at the bottom of the holder 2 to the stop. Due to the inclination of the holding device 2 and the bottom of the holding device 2 at an angle β to the horizontal slips due to the gravity of the letter with its original right upper edge in a predetermined corner of the holder 2, wherein the corner of a coordinate origin of an imaginary X / Y coordinate cross corresponds and the X / Y Koordina-Tenkreuz is parallel to the guide plate 3.

Inside the holding device 2 with the letter slot are sensors, e.g. Photoelectric sensors arranged, which detect the presence of a letter. In the guide plate 3 windows 4, 5 are incorporated for the fields to be printed on the imprint page of the envelope (address field, franking field). An ink jet print head 6 sliding on a guide rod 8 is connected to a belt 7. The belt 7 passes over a drive roller 12 and a deflection roller 13. With the drive roller 12 driven by a drive motor 11 thus the ink jet print head 6 can be moved in a known manner in the X direction and opposite thereto. A retaining plate 9, which runs on a second guide rod 14, is connected to a second drive 10. The details have not been shown separately, since the second drive 10 may be formed in a known manner. The latter includes, for example, a motor with a gear and a gear which engages in teeth of a guide rod 14 designed as a rack. Thus, a second mechanism is provided which can move the first mechanism, including the ink jet printhead 6, in the Y direction and, conversely, to an alternate printing position. The former print position and the alternate print position may overlap in the X direction. An overlap in the Y-direction is not provided, as this is excluded by the applicable postal regulations.

In the example shown, the inkjet printhead 6, which is movable by means of the aforementioned postage meter printing mechanism, is moved in an approximately meandering manner in order to carry out the imprinting in a time-optimized manner. In this case, the address field is initially run counter to the X direction before an offset of the inkjet printhead 6 against the Y direction is required, in order subsequently to pass through the address field in the X direction. In both phases of movement opposite to the X direction and in the X direction is printed. After a further offset of the inkjet printhead 6 in the opposite direction to the Y direction, the franking field is traversed again counter to the X direction and thereby printed. At the In addition, a further movement can be performed again counter to the X direction in order to control a starting position in the window 5 before the franking field is traversed.

Alternatively, with an ink jet printhead 6 of larger print width, the address field may first be traversed counter to the X direction before an offset of the ink jet printhead 6 against the Y direction is required to subsequently traverse the franking field in the X direction.

The control of the franking machine pressure mechanism and the ink jet print head 6 is effected by a known per se electronics with microprocessor control. The microprocessor is programmed accordingly, that from a starting position in which the ink jet print head 6 can be positioned to engage with a - not shown - cleaning and sealing device, a time-optimal sequence of movements is made.

The flow chart for a time-optimal control of Fig. 1a shows the process during the printing of a shipping address. The flow chart for a time-optimal control according to FIG. 1b shows the sequence during the printing of a franking imprint. In this case, time-consuming data processing operations are processed by the microprocessor in a time-interleaved manner with specific movement phases of the print head. A corresponding control program, according to which the microprocessor is programmed, is stored in a read-only memory. The microprocessor is programmed by the control program so that the information processes for generating a security imprint are executed parallel to certain movement sequences of the print head 6.

After a first step 100, in which the effected application of a letter has been detected, prompting steps 101, 102, 103, for entering an address (step 101) with automatic call of the associated ZIP code or a comparable transport destination code (step 102) as well as for entering the franking value (step 103). The prompting steps and the automatically determined ZIP code can be displayed via a display device (not shown). The microprocessor is connected to the read-only memory, the display device and an input device and determines in step 104 whether the inputs have been confirmed by means of the input device.

If no new entries are required according to at least one of the steps 101 to 103, it is possible to work with stored values which have to be confirmed. If not confirmed, the system branches to a waiting line. Otherwise, a branch is made from step 104 to a step 105 for generating the print image for the address field. Subsequently, in step 106, the start of the printing of the address field. The printing of the address field is a first task JOB1. According to the invention, further time-intensive tasks JOB2, JOB3,... JOBx are processed in a time-interleaved manner with respect to the first task. Such further tasks JOB2, JOB3, JOB4, JOB5 show steps 107, 108, 109, 110. Step 107 relates to the application of a hash algorithm, for example a SHA (Security Hash Algorithm), to the data elements or a reduction of the data set after a comparable mathematical function. The dataset includes the data elements generally agreed with the postal carriers. This data set is limited in the reduction such that the individual data elements are not reproducible again. However, only to the extent that changed records of different letters always differ. In step 108, the call of a secret key, which is called "private key" below. The latter is stored in a security module of the franking and addressing inextricably. The security module also stores a known asymmetric encryption algorithm. The encryption is performed in step 109.

A suitable known asymmetric encryption algorithm is, for example, the Digital Signature Algorithm (DSA), one of the Elliptic Curve Digital Signature Algorithms (ECDSA) or the ELGamal Algorithm (ELGA). These signature algorithms share a key pair which includes a private and a public key. The private key is a secret non-externally readable write key. And the public key acts as a read key for the signature and is accessible to everyone.

A program-specific execution of such an asymmetric encryption algorithm, for example the DSA (Digital Signature Algorithm), is still very time-consuming even with a modern processor. However, it must be preceded by the imprint of the signature in the franking field. According to the invention, the calculation is started when all required data is ready. The processing is time-interleaved with the printing in the address field, which is printed first and for which no processing of encryption algorithms is required. An alternative possibility is to carry out the processing during the adjustment of the inkjet printhead 6 in the opposite direction to the Y direction, when the postage meter printing mechanism operates relatively slowly. Preferably, however, is begun before this adjustment with the aforementioned processing.

For reasons of cost, postal carriers are required to read the printed data by machine. This can be done by appropriately designed impressions and OCR reader at the mail carrier even with alphanumeric characters. Optionally, in step 110, a conversion into a special machine-readable symbolism, such as barcode, 2-D barcode or PDF 417-symbolism, take place. The latter is from the company Symbol Technologies, inc. in EP 439 682 B1. Such two-dimensional barcodes are relatively space-saving versus one-dimensional barcodes and continue to reduce printing time.

Subsequent to the optional step 110, a branch is made to the interrogation step 111 illustrated in FIG. It is queried whether the address field has been completely printed. Between steps 110 and 111 there may be further query steps in which the termination of the other tasks (JOBs) is queried. The timing of the print head movement to the address printing is generally such that at the latest until the activation of the mechanism for moving the ink jet print head in the direction of the franking field, all JOBs are processed.
In step 112, the start of repositioning is triggered to control the inkjet printhead to the position for the imprint.
The execution of the next JOB, ie step 113, according to the invention is time-interleaved with the aforementioned positioning.
In step 113, the franking value is debited from the credit, which is stored in the post register of the security module.
Subsequently, in the next step 114, a call is made to the standard graphic elements of the franking imprint, and in a further step 115 a provision of the data elements for the franking imprint is carried out. In the following query step 116, a query is made as to whether the franking position has been reached. If this is not the case, the system branches to a waiting loop. Otherwise, in step 117, the machine-readable symbols and the visually readable data are printed, as well as the printing of the standard graphic elements. In the concluding step 118, the end of the processing is signaled via the display unit or beeper and prompted to remove the completely addressed and prepaid envelope.

An example of an impression on a mailpiece will be explained with reference to FIG. For a letter, the address field is arranged centrally. The Postempfängeradersse is in plain text and an associated ZIP code is printed as unencrypted barcode. The franking imprint is located in the periphery on the top right. A sender specified in the upper left corner is optional. For the USPS, an approximately 1 inch wide franking imprint is created with a machine readable area. Certain clear data and the signature are, for example, converted to PDF 417 symbolism and printed. Above the machine readable area is the visually (human) readable area and an area for the FIM code according to the US Postal Regulations. Because of the FIM code, an approximately 11 to 14 mm wide visually (human) readable area results for an approximately 1 inch wide franking imprint. Thus, the remaining width can be used for the machine-readable area.

The invention is not limited to a franking machine printing mechanism according to FIG. Thus, embodiments are suitable in which a lying mailpiece is provided with an address and franking imprint.
An alternative embodiment of the machine according to the invention comprises a letter feeder. This consists of a slot which is as wide as the widest letter to be processed and has an opening width which corresponds to the maximum letter thickness to be processed. Inside the holding device 2 with the letter slot are again sensors, such as photoelectric sensors arranged, which detect the presence of a letter. Beyond this opening is a receiving plate for receiving the letter, which can be raised in the vertical direction by means of a motor drive. Above the letter receiving plate a rigid plate is arranged with two recesses or recesses. These recesses correspond in size to at least the franking imprint or the addressing imprint and are arranged within the plate, as it corresponds to the arrangement of the two pressure fields on the letter to be processed. Immediately above the plate, the print head is located.
The motor-driven movement of the print head is measured, for example by means of an inductive displacement meter. Other displacement measurements in the drive motor or in the gearbox, which measure the rotation, can also be used. The measured path signals are fed to control electronics which synchronize these signals with the pressure control signals sent to the printhead.

The printhead is designed as a single color system with preferably black color. A particularly favorable in terms of consumption costs solution is achieved by using an ink jet printhead according to the patent of the applicant US 5,, 592,203.

• Hersteller Identifikationdaten(Vendor ID)
• Geräte Identifikationdaten (Device ID)
• Postbestimmungscode (Orig. ZIP)
• Datum (Date)
• Frankierwert (Postage Amount)
• Stückzahl (Piece Count)
• Prüfzahl (Check Digits)
• Versandzieladresse (destination adress)

The counterfeit security of the franking imprint is replaced by the use of special color by cryptographic encryption of reached certain data. This encryption creates a digital signature that is printed in addition to the record from which it was generated. Both components are printed on the envelope in machine-readable form. The following set of data should preferably be used:

• Manufacturer identification data (Vendor ID)
• Device identification data (Device ID)
• Postal Code (Orig. ZIP)
• Date)
• Franking value (Postage Amount)
• Quantity (Piece Count)
• Check number (check digits)
• Shipping destination address (destination adress)

• a) Der Manipulateur benutzt einen autorisierten Originalfrankierabdruck eines Briefes mit den im Frankierabdruck entsprechend kryptifizierten Daten und kopiert diesen Abdruck. Er benutzt im Adreßfeld jene Zieladressen, an die er Briefe zu senden beabsichtigt. Diese Zieladressen entsprechen aber nicht der im Frankierabdruck enthaltenen kryptografisch verschlüsselten Zieladresse des Originalabdruckes. Dieser Widerspruch ist durch Gegenüberstellung dieser beiden auf dem Briefumschlag enthaltenen Informationen seitens der prüfenden Postbehörde feststellbar.
• b) Der Manipulateur benutzt ebenso wie bei a) einen autorisierten Originalabdruck und kopiert diesen. Im Unterschied zu a) verwendet er im Adreßfeld aber auch die gleiche Adresse wie auf dem Originalbrief. Diese Kopie ist aus dem Vergleich der auf den Brief gedruckten Daten nicht mehr verifizierbar. Allerdings ist sie wirtschaftlich wertlos, denn die Kopie würde automatisch dem gleichen Empfänger zugestellt wie das Original. Fälschungen mit kommerziellem Hintergrund, etwa bei der Versendung von Werbeinformationen sind somit wirkungsvoll ausgeschlossen.

The first 7 data elements of the dataset make each corresponding franking imprint unique. However, this requires comparison with data stored in databases from earlier franking imprints. Since these can only be performed randomly for reasons of cost, there remains a high probability that a forgery will not be detected. By including the last data element, the destination address, in the cryptographic encryption, it is possible to detect a copy as a forgery without the use of historical data alone by checking the information printed on the letter. In the US, an address is largely expressed by a number code called ZIP codes. In its expanded form as ZIP + 4, it consists of 11 digits, which allow in many cases to completely determine the addressee, or at least the building or its immediate surroundings. The 11 digits are printed on the envelope in barcode format for machine-readable mailing machines. The franking and addressing machine according to the invention now not only prints this barcode in the address field, but also obtains the information by the corresponding digits also represented address in the encryption of the franking imprint. Two cases have to be distinguished regarding manipulation by means of copying:

• a) The manipulator uses an authorized original franking imprint of a letter with the correspondingly cryptified data in the franking imprint and copies this imprint. He uses in the address field those destination addresses to which he intends to send letters. However, these destination addresses do not correspond to the cryptographically encrypted destination address of the original imprint contained in the franking imprint. This contradiction can be established by comparing the two pieces of information contained on the envelope with the inspecting postal authority.
• b) The manipulator uses as well as a) an authorized original impression and copies it. In contrast to a), he also uses the same address in the address field as on the original letter. This copy is no longer verifiable from the comparison of the data printed on the letter. However, it is economically worthless, because the copy would automatically be delivered to the same recipient as the original. Counterfeits with a commercial background, for example in the sending of advertising information are thus effectively excluded.

Most postal authorities do not yet have as fine an address code as the US Post. For example, in Germany DPAG currently uses a code with only 5 digits. such a fuzzy code would leave a sufficiently large scope for commercial counterfeiting, eg when sending advertising material to different households with the same 5-digit postal code. In order to be able to use the device according to the invention for such conditions, the following is conceivable: The specification is expanded by including parts of the receiver address.

In a first variant, the name of the recipient or parts of the same is used. The name is represented in the form of alphabetic characters. For cryptographic encryption, these are converted into numbers. For example, the first letter of the recipient (personal name or company name) is filtered out and assigned a number corresponding to the position of the letter in the Latin alphabet. The widely used ASCII code can also be used for this. This number is now appended to the address code (5-digit postal code) and extends this by two digits. To increase security, other letters of the name can be converted and included. Each additional letter extends the address code by two digits.

In a second variant, the recipient name is not used to extend the address code, but the street name. A special form would be the use of the house number, because in this case the conversion into a numerical character can be omitted.

With the present invention, both the future security standard of the US Post (IBIP) is met, as well as a cost-effective combination of franking and addressing possible.

For the mechanical design of the solution according to the invention, there is a further embodiment. It is assumed again that the print head is narrower than the field to be printed. This necessitates a decomposition of the printing process into several phases. In each phase, only one strip of the entire print image is printed. The process corresponds in principle to the first embodiment. Between the phases, the duck head is shifted by the respective width of a print strip. For this purpose, a second movement device arranged orthogonally to the first movement device is provided in the letter plane. To save time when crossing the free space between franking field and address field, the both movement devices switched to a special mode. In this case, the second movement device is activated continuously until the printing position for the address field is reached. The first movement device is set to stand still. In order to be able to place the address imprint on the usual place even with larger letter formats, the duration of the special mode is linked to the letter format chosen by the customer. An automatic detection of the letter format by means of optical sensors is provided in a sub-variant. Each format is assigned in this case a certain width of the free center strip, which is stored in a memory of the machine. The special mode is then controlled by means of these stored format-specific values.

If the last print position in the first field (address field) is not aligned with the first print position in the second field (franking field), i. that an x-offset exists, a combined movement against the X / Y direction is particularly time-saving. The two independent drives are controlled according to known trigonometric relationships by the microprocessor.

To further accelerate the printing process, the printing phase itself can be divided once again into two sub-phases. In the first subphase, the printhead moves along the letter and prints the top half of the strip to be printed. At the end of this sub-phase, the print head is shifted in the orthogonal direction by half the width of the print strip and the direction of movement of the print head along the letter is rotated by 180 °. During this second subphase, the lower part of the print strip is printed.

The machine according to the invention is used in the following manner. The franking letter is manually inserted into the slot provided up to a stop. The said sensors detect its presence. The machine is switched to a first mode. This may be the franking mode, but also the address mode (hereinafter, the address mode is assumed). The customer is requested to enter the address. This address can be entered via a keyboard with which the device according to the invention is equipped, or via a PC connected to the device via a serial interface. Upon completion of this input, the customer will be prompted to enter the franking value. In a comfort version, the machine is also able to calculate the postage from other data, such as weight, size and shipping in a known manner. The address data are cryptographically encrypted together with other security-relevant data, such as franking value, date, machine number, and prepared for printing in the franking field.

After accounting for the value to be franked, the pressure is released. First, the receiving plate is raised with the letter lying on it and pressed the letter against the said plate. By this pressure of the surface to be printed against a rigid flat surface, the usual bumps filled letters are largely compensated. The standing above the recesses printhead thus receives a nearly constant distance to the letter surface to be printed regardless of the thickness and shape of the contents of the letter. This allows the use of a low-cost inkjet printhead. In another variant, the letter can also be brought into the print position immediately after feeding and before entering data. After the letter has reached the print position, the actual printing process is triggered. The print head can first print the franking field or first the address field. After completion of the printing, the receiving plate is lowered and the letter can be removed manually.

The advantage of a device with the features according to the invention is compared to the classic solution with separate devices for franking and address lettering in less effort. Future In the postal processing market, so-called PC frankers will also be used, as described, for example, in US Pat. No. 5,625,694. These are systems in which both the franking imprint and the address printing with a standard office printer, however, are applied only to unfilled letter cuvettes. Compared with these devices, the solution according to the invention has a decisive advantage: the printing of both information can be done on the already filled envelope. This filled envelope can be weighed in advance to accurately determine the required postage. The latter is particularly advantageous if the filling of the letters is done with different supplements and an estimate of the weight, as is necessary with PC frankers, is too inaccurate.

With reference to FIGS. 1a and b, the method steps and their time-optimized control have already been explained for a specific sequence of the individual JOBs. Alternatively, of course, another order is possible. The printhead is in the default position for printing the address field. The creation of a letter is reported by the sensors. The operator is prompted to enter the destination address of the letter. The entered address is displayed by means of a display. The validity of the entry is confirmed by the operator by pressing an ENTER key. After this confirmation, the processor automatically starts to search an address file. This file can be stored, for example, in a chip card inserted in the machine. The address entered is assigned an address code, eg ZIP code or zip code, by means of this file. Regardless of this background action, the user is prompted to enter the franking value. In a comfort version, the franking value is determined automatically. For this purpose, the operator must specify the data determining the franking value, such as the letter format, the weight of the letter and possibly the shipping method. The entered or calculated franking value is displayed and confirmed by the operator with the ENTER key. Without confirmation of the entries there will be no further processing.

Next, the print image for the address pressure is generated. The preparation of the printed image is carried out according to the wysiwyg principle, i. the impression corresponds to the address input shown on the display. Immediately after the print image generation is followed by the start command for the printout. If the printing is carried out with a height of the address field entprechend wide printhead, only one movement phase is required for the impression. The time required for this depends on the printing speed of the print head and the length of the address field. This time is at a printing speed of 100 mm / s and an address field length of 80 mm at about 1 second. During this time, the debiting of the franking value from the user's credit balance is carried out and the updating of the registers ascending, descending and accont is carried out accordingly. Immediately follows the generation of the visually evaluable part of the franking imprint. These include the standard graphic elements such as the post horn of the DPAG and data such as the date and the franking value. If these steps are executed, the message for the end of the address pressure is awaited.

When the address printing is completed, the print head is immediately controlled to the position for the franking imprint. In order to minimize the time for this movement, the address pressure on the left side of the address field has started and thus ended on the right side. From this position, the print head is now moved to the right side of the franking field to be printed. Including the franking pressure, the print head thus performs a movement which corresponds to a mirror-inverted Z. The angle of the diagonal is dependent on the length of the address field to be printed and the length of the franking field to be printed, as well as the selected letter format. At any rate, at this point in time, the machine has all the information to do simple trigonometric functions Move the print head away and thus optimally in time to its second print position.

If the same drive elements are used for this movement as for the printing movement itself, the print head requires about 1 second with a standard letter until the new print position is reached. During this time, the calculation of the machine-readable part of the franking imprint can be carried out. First, the digital signature is determined. In accordance with the information-based indicia program of the US Post Office, the o.g. Dataset of the Secure Hash algorithm applied. This algorithm, described in FIPS PUB 180-1, generates 160 bit information. Next, each machine's own private key is called. With its help, the DSA operation is applied to the 160 bit information. This algorithm, described in FIPS PUB 186, generates two 160-bit information. This information is placed in two 20-byte fields for printing. In principle, instead of the DSA algorithm, another crypto-algorithm may also occur, such as e.g. RSA.

The digital signature is converted together with the record that generates it into a machine-readable code. Since the space for such an imprint, which is to be printed together with the visually evaluable information, is limited, preferably a 2-dimensional barcode is used. Such a code is, for example, the PDF 417 described in Technical Report Monograph 8, Symbol Technologies, April 1992. When the printhead has reached its second printing position, the franking field printing begins. If, due to the limited width of the print head, several movement phases of the print head are required in order to print the entire franking field, the two-dimensional bar code arranged in the lower half is begun. This is followed by the expression of the visually evaluable part of the franking field. If the entire franking field is printed, the letter is released for removal given and the operator receives the request to remove the letter.

Through the multiple nesting of information processes and motion processes, an overall time-optimized process is achieved. Compared to a purely linear mode of operation, the achievable acceleration is approximately at factor two. If one adds the time for the one-time creation and removal of the letter, it becomes obvious that the franking and addressing machine is not only cheaper to buy compared to two separate special machines, but above all works much more time-saving. A standalone franking machine without the ability to print the address, but which should meet future security requirements, but would have to scan the already printed on the letters addresses, because a secure franking imprint requires the processing of this address information.

The two parts of the key pair, the private key and the public key, are generated by the manufacturer of the franking and addressing machine. The private key used to form the digital signature for each franking imprint is stored in a secure memory, preferably in the security module of the machine. The public key, which serves to verify the digital signature by means of a check device of the mail carrier in an evaluation point, is stored in a database. This can be operated by the manufacturer and the test device loads if necessary the public key herrunter. Alternatively, the manufacturer immediately sends the public key to a database, which is under the control of the test facility. The assignment of the matching key of the key pair can be done for example via a machine serial number or device identification data (Device ID).

It is provided for an evaluation in an evaluation point that all data printed on the mail piece are stored centrally. In the post office, the delivered mail can be checked with the help of the centrally stored data to see if copies of an imprint are used for forgery purposes. For each mail item delivered, an entry in the central database may be made in a particular area. A duplicate entry in the database indicates a fake print. By linking the postal recipient address with the postal value and number of pieces on the signature, it is impossible separately to copy one of the two postal recipient address or postal value for manipulation purposes.

It is further provided that each key pair, consisting of a private key and a public key, is valid for a limited time and can be changed suddenly to a specific date and time of the data center. The timing of switching occurs according to the current progress made in modern analysis techniques, such as differential cryptanalysis, and is such that an attack on the security of the system is likely to fail.

Claims (6)

1. A method for a franking and addressing machine comprising request steps for entering the franking value, steps for generating a related print image and for starting and completing the printing out, characterized by:

   - request (101) for entering the post destination address,

   - generation (105) of the print image for the address field,

   - starting (106) of the printing out of the address,

   - processing of signals of the relative movement between print head and letter, as well as

   - control of the information processes for generating a security print in parallel with certain sequences of movements of the print head (6).
2. A method according to Claim 1, characterized in that the sequences of movements of the print head (6) include the sequences during printing.
3. A method according to Claim 1, characterized in that the sequences of movements of the print head (6) include the sequences during the positioning before printing.
4. A method according to one of the Claims 1 to 3, characterized in that the information processes include a generation (109) of a digital signature.
5. A method according to Claim 4, characterized in that the generation (109) of the digital signature before printing the franking stamp image (117) is carried out in parallel with the first task of printing out the address and respective sequences of movements of a print head (6) so that on the whole there is achieved a time-optimized sequence of printing the address and the franking stamp image.
6. A method according to Claim 5, characterized in that, in the generation (109) of the digital signature, there are used an asymmetric encoding process and a private key, said signature being verifiable by means of an associated public key.

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