LASER BEAM PRINTER REGISTRATION-ADJUSTING APPARATUS

摘要

PROBLEM TO BE SOLVED: To highly accurately control a rotary polyhedral mirror-driving motor by temporarily stopping the operation of a frequency-dividing circuit and controlling the transmission of motor clocks independently during an effective term of a one-shot pulse signal corresponding to a time shift amount of image write timing signals of a main scan direction. SOLUTION: The apparatus has a phase difference-measuring circuit 6 which counts reference clocks generated at a reference clock generator 4 thereby measuring a time shift amount of a plurality of image write timing signals of a main scan direction generated when laser beams deflected by rotary polyhedral mirrors set to a plurality of laser scan units 121-124 are detected. The plurality of the counted measured values are stored in a plurality of registers 31-34, whereby one-shot pulse signals of times corresponding to the respective counted values are generated at pulse-generating circuits 71-74. During an effective term of the one-shot pulse signals, the operation of frequency-dividing circuits 101-104 is temporarily stopped and a phase of motor clocks is controlled with an accuracy of the reference clocks.