| 摘要 |
PURPOSE:To permit exposure control surely without giving any adverse influence upon an image forming plane by installing a photodetecting element at a place other than the center of an optical path conducting the reflected light or transmitted light from an original to a photoreceptor. CONSTITUTION:After the reflected or transmitted light from an original transmits through a lens mechanism 5, it arrives at a photoreceptor at the optical width W. A photodetecting element 22 is disposed in the bottom end part 26a of an optical path 25 apart from the center 26 of this optical path 25. The optical signal detected with the element 22 is converted to an electric signal by a photodetection circuit 35, and the pulse generation timing of a trigger pulse oscillation circuit 36 is controlled by this electric signal. Thereby, the conduction angle of a thyristor 32 is changed and the quantity of light of a fluorescent lamp 2 is controlled. By disposing the element 22 in such a position, the exposure is controlled surely without any adverse influence upon the image forming plane. |
