| 摘要 |
PURPOSE:To photodetect light at plural positions including the center part of a fluorescent lamp having the best stability of the quality of light and in an area irradiated with light actually, and to control the quantity of light of the fluorescent lamp with fidelity, by constituting a lamp housing so that it oscillates around the lengthwise axis of the fluorescent lamp, and fitting photodetecting elements nearly at the lengthwise center part and other parts and shaking the lamp housing. CONSTITUTION:When a motor 22 rotates except in a copy cycle, the lamp housing 12 shakes around the lengthwise axis 41 at some angle through a line 13. The size of the link 13 and the fitting positions of photodetecting elements 8A- 8C are so set that the photodetecting elements 8A-8C reach the light irradiation area during exposure, and consequently light used actually for the exposure is detected by the photodetecting elements 8A-8C and a detection signal synthesizing amplifier 27. Outputs of the photodetecting elements 8A-8C are summed up or averaged by the amplifier 27 to control electric power supplied to the fluorescent lamp 1, thereby adjusting its quantity of light to a specific value. |
