| 摘要 |
PURPOSE:To detect accurately the quantity of irradiation light in copying operation and to perform proper exposure, by arranging a photodetecting element to the position where the light irradiating an original from a light source is not prevented. CONSTITUTION:A reflecting mirror 10 arranged in parallel to a long and thin fluorescent lamp 1 has a lighting window 11 cut long and thin in the lengthwise direction of the fluorescent lamp 1 where the light from the fluorescent lamp 1 to the original 8 is not prevented and large influence upon the quantity of light to the original is not exerted. A photosensor 3 goes and returns to the overall length of the fluorescent lamp 1 throughout when the fluorescent lamp 1 turns on for copying and the total detection amount of light in a single going and returning period of the photosensor is detected; when the quantity of light of the fluorescent lamp 1 deviates from a set value, the electric power supply amount to the fluorescent lamp 1 is adjusted stepwise every time the photosensor 3 goes and returns once. Therefore, the quantity of light of the fluorescent lamp 1 is controlled to a specific value throughout the copying period. |
