JPS5550291A - Electronic copier - Google Patents

Abstract

PURPOSE:To erase the charge of only undesired part before exposure in a simple constitution, by erasing the charge on the photoreceptor by flickering the charge erasing lamp of variable radiation range at a specified timing. CONSTITUTION:Simultaneously with start of rotation of a photosensitive drum 14, a charge erasing lamp 27 lights up, and keeps lighting for the duration of a timer which is adjustable by means of a variable resistor, or the like, and a uniform charge by a charging device 21 in the section of distance L1 from point S on the photoreceptor 14 is erased, so that solid black latent image may not be formed in the undesired part at the front end of the image even in the absence of exposure by an exposure point E. When shutters 82, 83 forming a slit 81 in the lamp 27 are elastically deformed by means of a screw 84, the slit 81 varied, and the distnace L2 until the exposure point E after extinction can be adjusted, so that the radiation range of the lamp 27 may be optimally selected. On the other hand, the lamp 27 goes out in the specified seconds after the detection of the original platen returning to the original position, so that, similarly, solid black latnet image may not be formed in the undesired part at the rear end of the image. Thus, the charge in only the undesired parts befor exposure may be erased, depending on the fluctuations of parts, etc., in a simple constitution.