| 摘要 |
PURPOSE:To effectively utilize a space, etc. without staining a photodetector by a toner, etc., by providing a light receiving part of the photodetector in an area which does not obstruct main scanning on a locus. CONSTITUTION:A photodetector 9 is provided on a position which is comparatively distant from a vicinity 9a of a photosensitive body of one point chain line showing a conventional position. A laser luminous flux L2 emitted from a hologram lens 4 is converged temporarily at a point 5 on a locus D, and the luminous flux L2 is reduced to a beam of a small diameter. Accordingly, a light receiving part 10 of the photodetector 9 is provided on an area where the detector concerned does not obstruct effective main scanning, on the locus D. That is to say, 2 areas which are out of an effective deflection range W and within the maximum deflection range Y are generated, and in these areas F, F', the photodetector 9 is placed in the area F of the scanning start side. When it is placed in such a position, it functions in the same way as a conventional method and is not stained. |
