| 摘要 |
PURPOSE:To improve the efficiency of copying and the copying performance by installing an original size detecting sensor on a light shielding film which has been provided so as to be movable under a platen, so that an erasing light source can emit light selectively in accordance with a signal from the sensor. CONSTITUTION:When an operating switch is turned on, a light shielding film 6 is moved to an open side, and simultaneously, a sensor 8 also moves and detects the presence of an original A. By the sensor 8, a distance of a spread part of the original A is detected and stored in a controlling circuit. Also, the end part of the original A is detected, and thereafter, it is overtraveled by a set distance and its movement is stopped, and thereafter, the sensor is fed back again to the original end part position, and the detection of the original size is ended. On a copying band part C corresponding to the spread part of the original A is formed as a latent image, but when the copying form B passes through a black band latent image erasing light source 9, the black band part C is erased. The light emission time of the black band latent image erasing light source 9 is set by the width of the sheet part detected by the sensor 8 and a moving speed of a photosensitive belt 4. |
