| 摘要 |
PURPOSE:To maintain the best quantity of exposure and to stabilize copied image quality, by detecting the quantity of exposure of a photosensitive drum through a sensor which enters and exits freely, and controlling an exposure light source lamp. CONSTITUTION:A sensor 1 for the quantity of light which is freely put on and off the optical path between a polarizing mirror 10 and a photosensitive drum 1, detects the quantity of exposure of the drum by reflection from an original through an exposure lamp 8, etc., and an operational amplifier 12 compares the detected value with a set value which corresponds to the optimum quantity of exposure. A voltage control circuit 15 is controlled through a computer 14 according to the result of said comparison to vary the quantity of light emitted by the lamp 8, and thus the quantity of exposure which corresponds to an original image on the drum 1 is kept invariably to a uniform and adequate value without reference to variation in magnification, a dirty copying machine, a deteriorated lamp, etc., thereby stabilizing the quality of the copied image. |
