| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can prevent image quality degradation due to drooping while coping with a wide light-amount variable range. <P>SOLUTION: The image forming apparatus has an optical scanning unit 150 which scans a photoreceptor by a laser light outputted by a semiconductor laser, and a transmittance adjusting device 170 which changes an optical efficiency of the optical scanning unit 150 by inserting and removing an ND filter in and from its optical path. An exposure control part 120 uses the semiconductor laser in a region of a minimum or larger permissible emission amount wherein effects of drooping are permitted, and expands a light-amount variable range on the photoreceptor by insertion and removal of the ND filter. For example, when a light amount on the photoreceptor is to be lowered than that of a state in which the semiconductor laser is made the minimum permissible emission amount and the ND filter is removed, the ND filter is inserted. <P>COPYRIGHT: (C)2012,JPO&INPIT |
