| 摘要 |
PROBLEM TO BE SOLVED: To realize an image forming apparatus furnished with an excellent optical scanner with which the shift of the position of a focusing spot in a scanning direction accompanying the switching of resolution and the variation in light quantity do not occur in the case where the light beams in the scanning direction or subscanning direction are not parallel at a position where a switching lens is to be inserted. SOLUTION: The image forming apparatus having the optical scanner composed of a plurality of laser light sources with which the modulation frequency can be switched between a first stage and a second stage and a rotating polygon mirror which deflects and scans the light beams from the laser light sources. The image forming apparatus is characterized by that a mechanism is provided at a position where the light beams are not parallel in the scanning direction or the subscanning direction between the laser light sources and the rotating polygon mirror, and which mechanism selectively uses a phase body having no power at the modulation frequency in the first stage and a transmissive optical element having no power in the scanning direction at the modulation frequency in the second stage. COPYRIGHT: (C)2006,JPO&NCIPI |
