| 摘要 |
PURPOSE:To reduce the generation of defective copies, the down time of a machine or operator's load by automatically detecting a defective part such as a flaw and automatically inhibiting copying operation on a defective image forming position. CONSTITUTION:In a copying machine 1 using a photoconductive belt-like photosensitive body 3 formed like a loop by connecting its leading end and final end to each other and having light transmissivity and applying electrostatic charge and exposure to the photosensitive body 3, a leading end detecting mark 21 formed on the photosensitive body 3 is detected by a sensor 22 and the detected mark 21 is used as a reference position to determine an image forming position on the photosensitive body 30 in each size of transfer paper 9 to be used. On the other hand, light beams obtained by turning on all erase lamps 7 are transmitted through the photosensitive body 3 and the transmitted beams are received by a line sensor to detect the change of light quantity. Thus, a defective part 23 such as a flaw on the photosensitive body 30 is discriminated, the using validity/invalidity of each image forming position is discriminated and image formation on an image forming position corresponding to the using invalidity is inhibited. |
