Recorders – Light or beam recording – Including record receiver or handling means therefor
Patent
1989-12-18
1992-05-05
Fuller, Benjamin R.
Recorders
Light or beam recording
Including record receiver or handling means therefor
358298, G01D 1514, H04N 1036, H04N 123
Patent
active
051112175
ABSTRACT:
A non-impact dot printer such as an LED printer, records grey levels of each dot by pulse width modulating the exposure on-time for each LED. The on-time of each LED for each exposure is controlled by comparing a count, representing an exposure time with a time changing output of two counters. The improved printer and method of printing employs two counters that are counting at slightly different clock rates (or at the same rates but the counts change at slightly different times). A multiplexer associated with the comparator selects which counters output is to be compared with the comparator. A particular LED may be selectively illuminated for a picture element time period determined either solely by one or the other of the counters, or by the count of one counter and the count of the other. Because of the small difference between the clock rates used to change the outputs of the counter, uniformity control of the LED's can be significantly improved by allowing fine control of LED on time.
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Proceedings of the SID, vol. 21, No. 2, 1980 pp. 171-175; Nakaya et al, "Gray Scale Thermal Recording".
Eastman Kodak Company
Fuller Benjamin R.
Rushefsky Norman
Yockey David
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