Two pass thermal printing

Details Two pass thermal printing Two pass thermal printing

1986-10-01

1988-08-09

Broome, H.

Recorders

Thermal recording

400120, G01D 1510, B41J 320

Patent

active

047631376

ABSTRACT:
Heat accumulation in a thermal printhead is controlled by printing blocks of data along the print line in two passes when examination of the data shows the potential of excessive heating. The proportion of heat intensive or black parts in each block is determined by data processor 17 by examining the data for a line in memory 19. An accumulation is made assigning blocks having high heat density minus 2, blocks having intermediate heat density minus 1 and blocks having low heat density plus 1. When that figure is at minus two the next block is not printed until a second pass and the accumulation is set to zero. Where the accumulation is minus 1, print power is reduced for the next block, which is printed in the first pass. Excessive heat in the printhead results in machine damage and impaired print quality. A second pass is completely avoided where the data is such that this is unnecessary. This offers the potential of feeding ribbon only in blocks being printed, although ribbon feeding may be continued to achieve additional cooling.

REFERENCES:
patent: 4454516 (1984-06-01), Moriguchi et al.
patent: 4467363 (1984-08-01), Tench
patent: 4567488 (1986-01-01), Moriguchi et al.
patent: 4575731 (1986-03-01), Horlander
patent: 4590487 (1986-05-01), Noguchi et al.
patent: 4616941 (1986-10-01), Nagai
patent: 4638329 (1987-01-01), Nakayama et al.
patent: 4639741 (1987-01-01), Inove
patent: 4653940 (1987-03-01), Katsukawa
patent: 4675700 (1987-06-01), Nagira et al.
IBM Technical Disclosure Bulletin, entitled "All-Points-Addressable Printing with a Resistive Ribbon", vol. 29, No. 2, Jul. 1986, pp. 609-610.
IBM Technical Disclosure Bulletin entitled: "Enhanced Duty Cycle Prediction and Control for Wire Matrix Printers", B. R. Cavill et al., vol. 24, No. 11A, Apr. 1982, at pp. 5430-5432.

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