Electronic control arrangement for a laser printer

Abstract

The write lines of a color laser printer are maintained substantially equal throughout the printer's operation by an electronic control arrangement. At the factory, the write lines on all photoconductors of the color laser printer are calibrated to be substantially equal, and the ratio of each write line to a measuring line for each photoconductor is ascertained. During operation of the printer, the length of each of the measuring lines is periodically determined through counting the number of PELslice clock timing pulses produced from a PELslice clock operating at a fixed frequency determined during factory calibration. The length of the write line is determined by the product of the length of the measuring line and the factory calibrated ratio of the length of the write line to the length of the measuring line. After each periodic determination, PELslice clock timing pulses are selectively inserted into or removed from the PELslice clock timing pulses for all of the write lines but the write line, which is closest to the desired length, to increase or decrease their lengths to be substantially equal to the write line, which is closest to the desired length. The time for insertion or removal of each of the PEL slices into the train of PELslice clock timing pulses produced by the PELslice clock is determined with each preferably inserted at a non-active portion of a PEL. Each insertion or removal of a PEL slice also may be offset from its determined position.