| 摘要 |
PURPOSE:To adjust the picture write position with high accuracy in a laser beam printer by selecting and outputting one of pulse signals from plural pulse signal generating means in response to the production or a synchronizing detection signal in a photodetector. CONSTITUTION:An optical sensor 100 is arranged to a manual scanning start point of a manual scanning region of a scanning beam, senses a scanning beam prior to each main scanning, gives a synchronizing detection signal as its output and applies it to a latch circuit 114. A plural-pulse signal generating circuit 112 generates a pulse signal having the same frequency as that of a picture scanning clock and whose phase is deviated sequentially. In this case, one of the pulse signals from the means 112 is selected and outputted by a clock selection means 116, and which pulse signal is to be selected by the means 116 with respect to the synchronizing sensing signal in the light sensor is set variably by a clock setting circuit 100. Thus, the picture write position of the laser beam printer is finely adjusted.
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