Data Products Corporation

Werner Loewenthal

Yuen W Wong

Stan D Shurygailo

David R Webb

Patrick N Leung

A printer accesses from a bit mapped raster matrix of an image to be printed, a group of bits corresponding in number to the number of printing elements of the printhead. This group of bits is used to drive the printing elements of the printhead so as to print the image. In the printers having raster scanning printheads, the selected groups of bits are accessed from the bit mapped raster matrix synchronously with the raster scanning of the printhead.

Printer having a multiple scan line printhead controller

Four microprocessors type Intel 8051 collectively map one print buffer containing 136 ASCII character codes, each of a nominal 64 different types, into the control of 136 print hammers at an associated 136 columnar print positions. The print hammers are controlled to fire upon a selected one scan time interval of 690 microseconds, one of a total of 67 such scan time intervals within a 46.7 millisecond print time period. Print hammers are controlled to fire at a particular scan time interval in order to print a character from a then oppositely juxtaposed character font upon a circulating print band. The mapping being too time consuming to be done entirely within the print time period and within each of the scan time intervals, the microprocessors instead assign, during a 20 millisecond paper feed period prior to the print time period, a scan time value to each character code, which value corresponds to that one future scan time interval at which the print band character font corresponding to each character code will appear at that print position wherein the character corresponding to the character code is to be printed. Later, during each successive scan time interval, all stored scan time values are compared to the current scan time interval number. Print hammers at all print positions comparing equal are fired, printing after all scan time intervals a complete print line.

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North Hollywood, CA, United States of America

Werner Loewenthal