| 摘要 |
PURPOSE:To prevent image recording or image reading to be executed on the basis of a picture element clock signal from the influence of jitter by changing the period of the picture element clock signal in accordance with the quantity of jitter. CONSTITUTION:A picture element clock signal S2 formed in a beam scanner to be used for image reading or recording is operated to remove the influence of jitter. The beam scanner is provided with photodetectors 25, 26 for detecting the passage of an optical beam 11 through a main scanning starting point and the passage through a man scanning end point respectively and a clock signal forming circuit 27 for finding out the time required for main scanning every mirror face of a rotary polygon mirror 13 on the basis of the outputs of the photodetectors 25, 26 and changing the period of the picture element clock signal S2 so that the period is proportional to the required time of the mirror face used for the main scanning. Consequently, the influence of jitter due to the uneven rotation or the like of the ratary polygon mirror 13 can be removed and the accuracy of the image reading or recording can be improved.
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