Incremental printing of symbolic information – Ink jet – Combined
Reexamination Certificate
1998-09-02
2001-06-19
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Combined
C347S004000, C347S104000, C346S024000, C400S596000, C400S708000, C101S091000
Reexamination Certificate
active
06247774
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a postage meter machine of the type having a digital printer device with a guide plate and a transport arrangement with a conveyor belt for moving items to be printed past the printer device, and a control unit which generates print control signals for a printhead of the printer device, and having a letter sensor disposed in the guide plate preceding the printhead in the transport direction which supplies a sensor signal to the control unit to ready the printer device for printing.
2. Description of the Prior Art
Postage meter machines can be especially efficiently utilized for franking mail beginning with a moderate to high volume of letters or other postal matter to be mailed. Differing from other printers, a postage meter machine is suitable for processing filled envelopes, possibly also with very different formats. The terms letter, piece of mail or print medium as used herein include all types of envelopes or other print-receiving media. Postal matter, file cards, labels or self-adhesive paper tapes or similar material can be employed as the print medium.
Modern postage meter machines utilize fully electronic digital printer devices. For example, the postage meter machine T1000 of Francotype-Postalia AG & Co. employs a thermal printing unit. With this, it is possible to print arbitrary texts and special characters in the franking stamp printing region. A thermal transfer postage meter machine disclosed in U.S. Pat. No. 4,746,234 has a microprocessor and is surrounded by a secured housing that exhibits an opening for the delivery of a letter, thus the position and movement of the letter can only be indirectly determined. A mechanical letter sensor (micro-switch) communicates a print request signal to the microprocessor as an indication of the position of the letter during transport thereof through the machine. The necessity of precise timing as articles are transported at high speed through the machine results in a high outlay for adjusting triggering of the micro-switch, which is disadvantageous. The microprocessor controls the drive motors and an thermal transfer printing head based on the sensor output. An encoder communicates a signal derived from the transport of the thermal transfer inking ribbon (which moves in a path around a series of rollers) to the microprocessor as further information about the letter transport movement.
European Application 189 268 discloses a receptacle means for inking ribbon cassettes. The sidewall of the cassette has an opening through which a roller projects for seating the inking ribbon in order to receive the drive force therefrom, or to transmit the drive force to a friction roller that is coupled to an encoder disk. The inking ribbon speed approximately corresponds to that of the printed matter that is transported between the inking ribbon and the counter-pressure roller. Given slippage resulting in a lack of synchronization between the letter transport components and the thermal transfer inking ribbon transport components, the derived signal is no longer correct, which correspondingly influences the appearance of the print format.
U.S. Pat. No. 5,495,103 discloses an arrangement for printing on a piece of mail triggered in a time spacing with a time control. Printing is started with a reflected light barrier and with a timer, so that the print format can be exactly positioned on the piece of mail by the user. There is always the possibility, however, that a letter jam will arise given high letter transport speeds. The point of the print triggering shifts when the letter is moved faster. The stamp imprint thus no longer fits completely on the mailing. The required adjustment (made by setting potentiometer) that the user is supposed to undertake according to the printing speed is disadvantageous. The user must undertake an undefined number of trials for adjustment, and it is uncertain what setting of the potentiometers is most likely of success.
German PS 196 05 014 discloses an embodiment of a printer device (JetMail®) that, given a non-horizontal, approximately vertical letter transport, implements a franking print with an ink jet printhead arranged stationary in a recess behind a guide plate. A print sensor for recognizing the start of a letter is arranged before the recess for the ink jet printhead and collaborates with an incremental sensor. By means of pressure elements arranged on the conveyor belt, the letter transport is slip-free and the sensor signal derived during the transport is correct, which has a positive influence on the quality of the print format. Given thick letters, however, the letter's leading edge is not always squared, but can be more or less rounded, so that the start of the letter is not exactly detected.
SUMMARY OF THE INVENTION
An object of the invention is to provide a print control arrangement for a postage meter machine that avoids problems that particularly result from high printing speeds given high printing volume of different types of mail (mixed mail). The control arrangement should be able to recognize a letter jam in time, and to take steps to avoid such a jam insofar as possible, given mixed mail as well. The control arrangement should allow adjustment of the stamp offset independently of the printing speed and without adjustment outlay.
The above objects are achieved in a postage meter machine equipped with a transport path control and with means for preventing a paper jam. The control arrangement of the postage meter machine includes a microprocessor to which an encoder and a print sensor are connected, the latter being arranged in a guide plate lying upstream (in the letter transport direction) directly in front of the printhead. The print sensor supplies signal for the start of printing and serves for recognizing the start of a letter. As a result of the connected encoder, the letter speed in the transport direction is taken into consideration in the calculation, so that the distance or path that the letter traversed can be exactly determined. The start of printing is always exactly detected by the print sensor, which can be fashioned as a transmitted light barrier. No adjustment outlay whatsoever is required due to the exact path measurement. An arbitrary stamp offset thus can also be exactly realized in conjunction with the exact path measurement.
Also in accordance with the invention, a preparation sensor is arranged in the guide plate spaced from the print sensor and upstream therefrom, so that the two sensors are spaced from one another in a predetermined way in the transport direction, and a first belt travel path is determined by a defined letter. The preparation sensor is thus farther from the printhead than the print sensor. A supplied letter passes through its position first. The microprocessor, consequently, is supplied with a first signal by the preparation sensor before it is supplied with the second signal for the start of printing. The length of a respectively supplied letter thus can also be calculated from the sensor signals, this being subsequently checked to determine whether it is in a predetermined, valid size range. Inventively, a paper jam in the above-described postage meter machine can be identified by the microprocessor if that a letter covers at least one of the above sensors for a predetermined belt travel path of the conveyor belt. Together with a memory, the microprocessor forms a belt counter that is updated on the basis of the signals supplied by the encoder, so that an exact path measurement of the belt travel path is enabled. On the basis of the preparation and print sensor interrogations and the determination of the belt travel path, the microprocessor is programmed to identify a paper jam, a valid letter format or an error and to undertake the print control in a precise, path-controlled manner.
REFERENCES:
patent: 4478508 (1984-10-01), Kato et al.
patent: 4686540 (1987-08-01), Leslie et al.
patent: 4707704 (1987-11-01), Allen et al.
patent: 4746234 (1988-05-0
Barlow John
Do An H.
Francotyp-Postalia AG & Co.
Schiff & Hardin & Waite
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