| 摘要 |
PURPOSE:To obtain a high-quality copy image, by providing a photodetector which detects the quantity of light from an original and moving this photodetector in the direction crossing the direction of original scanning to detect the density of the original. CONSTITUTION:A microfilm original 1 is illuminated with an illuminating system, and the image light of the original 1 passes through a projection lens 5 and is reflected by plane mirrors 6 and 7 and is projected to a photosensitive drum 10 through a slit 9 of a slit plate 8. A photodetector 20 which detects the picture density of the original is provided on a movable plate 21, which is arranged freely movably on the slit plate 8, and is placed near the slit 9. The movable plate 21 and the photodetector 20 are moved as one body in the direction of an arrow E by a wire 22, and the photodetector 20 is moved in the direction orthogonal to directions of arrows A and B of original scanning. The photodetector 20 detects the quantity of light from the original, and the detection signal is sent to a lamp luminance controlling circuit 27 to control the luminance of a lamp 2, and thus, an optimum exposure is obtained. |
