| 摘要 |
In a multibeam scanner, a control unit includes a velocity detecting circuit detecting a conveying velocity V of a photosensitive body; a comparison circuit comparing the detected conveying velocity V to a reference conveying velocity V0; a light intensity control circuit 93, a modulation circuit 94, an LD1 control circuit 95, and an LD2 control circuit 96. The LD1 control circuit 95 and LD2 control circuit 96 issue drive signals to laser diodes LD1 and LD2. The laser diodes LD1 and LD2 emit laser beams LB1 and LB2 that are modulated according to image signals outputted from the modulation circuit 94. The laser beams LB1 and LB2 are deflected by a polygon mirror onto the photosensitive body and perform a main scan over neighboring scanning lines SL1 and SL2, while the photosensitive drum is rotated. The light intensity from the laser diode LD1 is adjusted when the velocity of the photosensitive drum differs from a prescribed velocity in order to achieve a balanced image density.
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