EP0901108B1 - Franking machine - Google Patents

Description

The invention relates to a franking machine, according to the type specified in the preamble of claim 1, which is equipped with a travel control and with means for at least detecting a paper jam.

From a medium to higher number of letters to be sent or other mail items, franking machines for franking the postal items can be used particularly effectively. In contrast to other printers, a franking machine is suitable for the processing of filled envelopes, possibly also of a very different format. Of course, if the word letter, mail piece or print carrier is used for the sake of brevity, this includes all types of envelopes or other record carriers. As a record carrier mail, index cards, labels or self-adhesive strips of paper or similar material can be used.

Modern franking machines employ fully electronic digital printing devices. For example, Applicants' T1000 franking machine has a thermal printing unit. With this it is in principle possible to print any text and special characters in the franking stamp printing area. The thermal transfer postage meter known from US 4,746,234 has a microprocessor and is surrounded by a secure housing having an opening for the supply of a letter, wherein the position and movement can only be determined indirectly. A mechanical letter sensor (microswitch) transmits a print request signal to the microprocessor regarding information about the position of the letter as it is being fed. A disadvantage is the high adjustment effort for the triggering of the microswitch. The microprocessor then controls the drive motors and a thermal transfer print head. An encoder transmits a signal derived from the thermal transfer ribbon transport signal to the microprocessor as information for letter transport movement.

From EP 189 268 B1 a recording device for ribbon cartridges is known. The side wall of the cassette has an opening through which a roller can pass for engagement with the ink ribbon to receive the drive force therefrom or to transfer to a friction roller which is coupled to an encoder disk. The ribbon speed corresponds approximately to that of the printed material, which is transported between the ink ribbon and counter-pressure roller. With a slip between letter transport and thermal transfer ribbon transport, the derived signal is no longer correct, which affects the print image appearance accordingly.

From US Pat. No. 5,495,109 (PB) an arrangement for a time-triggered pressure on a mail piece by means of timing is known. By means of a reflex light barrier and by means of a timer, the printing is started, so that the printed image on the mail piece by the user can be accurately positioned. However, there is the possibility that at high letter speeds a letter jam arises. If the letter moves faster, the point of the pressure release shifts. Thus, the stamp imprint no longer fits completely on the mailpiece. The disadvantage is the required adjustment, which the user should make according to the printing speed. The user must make an indefinite number of attempts to adjust It is uncertain which setting of the potentiometer is promising.

In DE 196 05 014 C1, an embodiment for a printing device (JetMail®) has already been proposed, which carries out a franking printing by means of an ink jet print head arranged stationary behind a guide plate in a recess in the case of a non-horizontal, approximately vertical letter transport. A pressure sensor is arranged for Briefanfangserkennung just before the recess for the inkjet printhead and cooperates with an incremental encoder. By arranged on the conveyor pressure elements of the letter transport is free of shuffle and the derived during transport encoder signal is correct, which positively affects the print quality. For thick letters but the letter edge is not always edged, but may be more or less rounded, so that the letter beginning is not detected accurately.

The invention has for its object to provide a control that avoids problems that result especially at large print volumes of different post (mixed mail) from high printing speeds. An emerging letter jam should also be recognized in good time with mixed mail and avoided as far as possible. The stamp offset should be adjustable regardless of the printing speed and without adjustment effort.

The object is achieved with the features of claim 1.

The franking machine is equipped with a path control and with means for preventing a paper jam. A control device of the franking machine includes a microprocessor to which an encoder and a pressure sensor are connected, the latter being arranged upstream of the print head in a guide plate upstream of the print head. The pressure sensor provides signal for the start of printing and is used for letter start detection. By the connected encoder the letter speed in the direction of transport is taken into account in the calculation, so that the way is exactly determined, which was covered by the letter. Due to the pressure sensor designed as a photoelectric sensor, the start of printing is always accurately detected. Because of the exact distance measurement no adjustment effort is necessary. in the In connection with the exact position measurement, therefore, any stamp offset can be exactly realized.
According to the invention, a preparation sensor is arranged at a distance from the pressure sensor post upstream in the guide plate, so that both sensors are spaced from each other in the transport direction in a predetermined manner, wherein a first Bandverfahrweg is determined by a defined letter. The preparation sensor is thus further away from the printhead than the pressure sensor. From a supplied letter whose position is passed through first. The microprocessor is therefore supplied by the preparation sensor with a first signal before the second signal for the start of printing. From the sensor signals, the length of the letter is thus calculated for each letter supplied, which is then checked whether it is still in a predetermined valid range. According to the invention, a paper jam in the above-described postage meter for the microprocessor can be determined by a letter covering at least one of the above sensors for a predetermined band travel of the conveyor belt. The microprocessor together with a memory forms a tape counter, which is updated on the basis of the signals supplied by the encoder, so that an exact path measurement of the tape travel path is made possible. The microprocessor is programmed to detect a paper jam, a valid letter format or an error due to the preparation and print sensor queries and the determination of the tape travel path and to make the pressure control in a precisely controlled manner.

Figur 1,

Details der erfindungsgemäßen Druckeinrichtung,

Figur 2,

Blockschaltbild zur Ansteuerung der Druckeinrichtung,

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:

FIG. 1,

Details of the printing device according to the invention,

FIG. 2,

Block diagram for controlling the printing device,

1 shows details of the printing device according to the invention for printing a standing on an edge 31 letter envelope 3. This consists essentially of a conveyor belt 10, one orthogonal to the transport plane (XZ plane) and arranged above this in the XY plane guide plate 2 and an ink print head 4. The Letter envelope 3 is turned and rotated so that it rests with its surface on the guide rails 23 of the guide plate 2. The guide plate 2 is preferably inclined at an angle y = 18 ° to the solder. Guide plate 2 and conveyor belt 10 together form an angle of 90 °. The standing on the conveyor belt 10 envelopes 3 are inevitably on the guide plate 2 by the oblique position of the same and are also pressed by pressure elements 12, which are mounted on the conveyor belt 10. During movement of the conveyor belt 10, the letters 3, carried along by the pressure elements 12, slide along the guide rails 23 of the stationary guide plate 2. An extension 12132 of the pressure elements 12 slides on a backdrop with the deflections 81 and 82, which allows the pressing or releasing the envelope before or after printing. In the guide plate 2, a recess 21 is provided for the ink jet print head 4. The guide plate 2 is in the transport direction downstream in the region 25 behind the recesses 21 relative to the contact surface for the letter 3 set back so far that the printed surface is certain to be free. The arranged in the guide plate 2 sensors 17 and 7 are used for preparation or Briefanfangserkennung and pressure release in the transport direction. The transport device consists of a conveyor belt 10 and two rollers 11. One of the rollers 11 is equipped with a motor 15 drive roller. Both rollers 11 are preferably designed in a manner not shown as toothed rollers, corresponding to the conveyor belt 10 as a toothed belt, which ensures the unambiguous power transmission. An encoder 5, 6 is coupled to the drive roller 11. Preferably, the drive roller 11 is firmly seated with an incremental encoder 5 on an axis, also not visible. The incremental encoder 5 is designed, for example, as a slotted disk, which interacts with a light barrier 6.

2 shows a block diagram for controlling the printing device 20 with a control device 1. The control device 1 comprises a microprocessor 91 and known storage means 92, 93, 94 and date circuit 95, a keyboard 88 and a display unit 89 and an application-specific circuit ASIC, having an interface circuit 97 and communicating with the microprocessor 91 in communication. The ASIC of the controller 1 also includes the interface circuit 96 to the interface circuit 14 located in the machine base and provides at least one connection the sensors 6, 7, 17 and to the actuators, for example to the drive motor 15 for the roller 11 and to a cleaning and sealing station RDS for the inkjet printhead 4, and to the inkjet printhead 4 of the machine base. The basic arrangement and the interaction between the ink jet print head and the RDS are the non-prepublished German application 197 26 642.8 removable, entitled: Arrangement for positioning an ink jet print head and a cleaning and sealing device.

According to the invention, the pressure sensor 7 is designed as a transmitted light barrier. For example, a transmitting diode of the photoelectric sensor of the pressure sensor 7 in the guide plate 2 and at a distance, according to the maximum thickness (in the Z direction) of the mailpieces (letters), a receiving diode of the photoelectric sensor is arranged. For example, the receiving diode is attached to a support plate 8 on the backdrop. Equally effective would be a reverse arrangement with receiving diode in the guide plate 2 and transmitting diode on the support plate 8. Thus, the letter beginning (edge) are accurately detected in thin as well as thick letters in the same way. The pressure sensor 7 provides the start signal for path control between this sensor 7 and the first ink jet printhead nozzle. The pressure control is based on the path control, taking into account the selected stamp offset, which is entered by keyboard 88 and stored non-volatile in the NVM 94 memory. A planned imprint thus results from stamp offset (without prints), the franking print image and possibly further print images for advertising clichés, mailing information (optional prints) and additional editable messages.

It is envisaged that the individual printing elements of the print head are connected within its housing with a print head electronics and that the print head for a purely electronic pressure can be controlled. The encoder 5, 6 supplies a signal to the microprocessor for every n pressure gaps. This is done by interrupt function. At each interrupt, a tape counter is also updated, which records the progress of movement of the motor 15 and thus the conveyor belt 10. Each pressure column is preferably 132 μm wide. The tape counter here is a two-byte counter, ie 2 ¹⁶ -1 counter readings are possible. Thus, a maximum letter path of W _max = 65535 * 132μm * n can be detected.

With the preparation sensor 17, a letter evaluation routine is initiated. For this purpose, 94 registers are created by the microprocessor 91 in the memory, in which per letter the tape counter value when reaching the letter leading edge and when reaching the letter trailing edge are written as variables. From the difference of the two values (initial value ₁₇ for letter edge or stop value ₁₇ for letter trailing edge) is from the microprocessor 91, the letter length L = stop value ₁₇ - determined starting value _17th The microprocessor can then determine the format if the letter length corresponds to a tape path predetermined for a valid format. The preparation sensor 17 may preferably be formed as a reflex light barrier, because the formats for letters deviate so much in size, so that a large tolerance in the letter edge recognition is permitted.

• die ermittelte Brieflänge L einen Mindestwert L_min erreicht oder überschreitet (L ≥ L_min) und
• die ermittelte Differenz der Variablenwerte (Drucksensor_Briefstartwert₇ minus Vorbereitungssensor_Briefstartwert₁₇), d.h. wenn der Verfahrweg W, einen ersten definierten Bandverfahrweg W_def1 entsprechend dem Abstand der beiden Sensoren 7 und 17 voneinander (einschließlich einen bestimmten +/-Toleranzwert) nicht überschreitet (W ≤ W_def1).

If the letter length L is shorter than the planned impression, an error message is output. If the difference between the two values is shorter than a predetermined length, ie at L <L _min , a fault without a letter is assumed. There is no error message. Upon receipt of the signal from the pressure sensor 7, the letter evaluation is completed. The microprocessor 91 is programmed to recognize and accept a letter as such when:

• the determined letter length L reaches or exceeds a minimum value L _min (L ≥ L _min ) and
• the determined difference of the variable values (Drucksensor_Briefstartwert ₇ minus Bereitungssensor_Briefstartwert ₁₇ ), ie when the travel W, a first defined band travel W _def1 corresponding to the distance between the two sensors 7 and 17 from each other (including a certain +/- tolerance _value ) does not exceed (W ≤ W _def1 ).

The travel path W of the _{conveyor belt} 10 is at slip-free transport of a letter or similar mail piece equal to the defined first Bandverfahrweg, for example, W _def1 = 100 mm. In the case of slip-tight transport of a letter, the band travel path W _{def1 is} defined as the sum of a tolerance _value and the sensor distance between two sensors 7 and 17 in the transport _direction . The preparation sensor 17 detects the letter leading edge, which is registered by the microprocessor to start the tape counter, which adds up the encoder pulses until the letter leading edge reaches the pressure sensor 7.

The accumulated number of pulses is compared with the number of pulses corresponding to the path between the preparation sensor 17 and the pressure sensor 7. The permissible deviation for the first defined band travel W _def1 is 10%. A slippage transport of a letter may possibly lead to a traffic jam and leads to an exceeding of the defined first Bandverfahrweges W _def1 .

In the further course of the processed by the microprocessor 91 routine both sensors 17 and 7 are used to detect a paper jam. The pressure sensor 7 detects the letter leading edge, which is registered by the microprocessor to register in conjunction with the signal from the preparation sensor 17, if necessary, a letter jam. A paper jam in the above-described franking machine becomes detectable for the microprocessor 91 in that a letter covers at least one of the two sensors 17 and 7 for a second predetermined tape travel, preferably of approximately W _def2 > 400 mm.
If the difference Drucksensor_Briefstartwert ₇ minus PreparationSensor_Briefstartwert ₁₇ greater than 400 mm, this can not be caused by a large letter format, but can only be interpreted as a malfunction. It is provided that the microprocessor 91 determines the letter length from the difference of the two values corresponding to the letter trailing edge and letter leading edge detected by one of the sensors 7 or 17, an error message being output if the letter length is longer than the predetermined tape path. In particular, it is provided that the microprocessor 91 values supplied from the difference of the two from the tape counter initial value ₁₇ for the detected by the sensor 17 letter edge or stop value ₁₇ for the detected by the sensor 17 Letter trailing edge, the letter length L determined (with L = stop value ₁₇ - Start value ₁₇ ). Thus, the format can be determined with one of the sensors, wherein the determined letter length corresponds to a predetermined for a valid format Bandverfahrweg or lies in one of the areas defined for formats.

The pressure control or sensor queries are therefore all path-controlled. In addition to or between the sensors 7 and 17, further sensors may be arranged for more differentiated determination of a valid letter format and / or for path control of the franking machine or a franking system.

FIG. 2 also shows a further interface circuit 99, which is connected to the right via a data cable 19 with an interface circuit 18 of the downstream post-deposition station and permits its control by the control device 1. Another peripheral device to the left of the franking machine base comprising the control device 1 and printing device 20 is preferably an automatic delivery station 28 and connected to its interface circuit 13 via cable 16 and to an interface circuit 98 of the ASIC.

It is envisaged that further sensors are arranged in the abovementioned further stations for detecting the letter edges, which are coupled via the aforementioned interfaces to the microprocessor 91 in the control device 1 in order to enable or monitor the system operation.

The non-prepublished German application 197 11 997.2 is a suitable for the peripheral interface embodiment for several peripheral devices (stations) removable. It is entitled: Arrangement for communication between a base station and other stations of a mailing machine and their emergency shutdown.

The printing device can also be realized differently from the previously described embodiment. The invention is not limited to the present embodiment, as obviously other other arrangements of the invention can be devised based on the same spirit of the invention as defined by the appended claims.

Claims (7)

1. A franking machine with a digital printing device (20) that comprises a guide plate (2) and a transport device with a transport belt (10) for print media (3) and is controlled by a control unit (1) that generates printing control signals for a print head (4) in order to print a respective printed image on the surface of the print medium while the print medium (3) is transported past the print head (4), a printing sensor (7) being arranged in the guide plate (2) before an opening (21) for the print head (4),
   characterized in

   - that a preparatory sensor (17) is arranged in the guide plate (2) upstream of and in a pre-defined distance from the printing sensor (7);

   - that the control unit (1) includes a microprocessor (91) to which an encoder (5, 6) for determining the belt travelling path of the transport belt (10), the preparatory sensor (17) and the printing sensor (7) are connected that are positioned in transport direction upstream of the print head (4) and are arranged in the guide plate (2) in a distance from one another in transport direction, wherein the microprocessor (91) and a memory (94) together form a belt counter that is updated on the basis of the signals delivered by the encoder (5, 6); said microprocessor being programmed

   - to perform printing control in a path-controlled manner using the means of the aforementioned transport device, of the preparatory sensor (17) and of the printing sensor (7), wherein the microprocessor (91) registers the front edge of the letter detected by the preparatory sensor (17) in order to start the belt counter that sums up the encoder pulses until the front edge of the letter reaches the printing sensor (7) and the summed-up pulse number is compared with a pulse number corresponding to the path between preparatory sensor (17) and printing sensor (7); and

   - to detect a paper jam, a valid letter format or an error by means of polling the preparatory and printing sensors and determining the belt travelling path, wherein the microprocessor (91) determines, on the basis of the difference of the two values supplied by the belt counter: a) start value for the front edge of the letter detected by the preparatory sensor (17), b) stop value for the rear edge of the letter detected by the preparatory sensor (17), the length of the letter L = stop value - start value.
2. A franking machine according to claim 1, characterized in that the printing sensor (7) is designed as a transmitted-light barrier.
3. A franking machine according to claims 1 to 2, characterized in that the preparatory sensor (17) is designed as a reflective-mode light barrier.
4. A franking machine according to claims 1 to 3, characterized in that a paper jam in the above described franking machine can be detected by the microprocessor (91) by the fact that a letter covers one of the sensors (7, 17) for a pre-defined belt travelling path.
5. A franking machine according to claim 4, characterized in that the microprocessor (91) determines the length of a letter from the difference of the two values corresponding to the rear edge and the front edge of the letter detected by one of the sensors (7, 17), an error message being issued when the length of a letter is longer than the pre-defined belt travelling path.
6. A franking machine according to claims 1 to 3, characterized in that the microprocessor (91) determines the length of a letter or its format from the difference of the two values for front edge and rear edge of the letter, an error message being issued when the length of a letter is shorter than the planned print.
7. A franking machine according to claims 1 to 3, characterized in that further detectors are arranged in further stations for detecting the letter edges that are coupled via interface with the microprocessor (91) in the control unit (1) in order to enable and/or monitor the system operation.

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