| 摘要 |
PURPOSE:To set a scanning line at a certain position on a photodetecting surface and to suppress jitters, by providing a synchronizing photodetecting element at the position f a sagittal image surface at the position of the photodetecting element. CONSTITUTION:An image forming lens system is formed with the combination of an ftheta lens Lfq for compensation of fall and a cylindrical lens Lc. A photoreceptor surface P and a photodetecting elemnt PD which is contiguous to the surface P are provided at the outside of a photoreceptor P. The curve of a sagittal image surface S is larger at the position of the element PD than the edge of a picture image, and the shift of position increases for the scanning line on the photodetecting surface. Therefore the synchronizing photodetecting element PD is set at the position of the surface S at the position of the PD and not at the same position as the surface P. |
