| 摘要 |
PURPOSE:To control surely meandering of an image carrier by detecting a part of an irradiated light, which skirts the outside edge of an end part in the breadthwise direction of the belt- shaped image carrier, with a light detecting means. CONSTITUTION:Two photodetectors S1 and S2 are arranged near one side of the end part in the breadthwise direction of a belt-shaped photosensitive body 8 for the purpose of receiving the scan optical beam from a scanner 5. These photodetectors S1 and S2 are provided in accordance with positional slippage allowable limit positions of the belt-shaped photosensitive body 8; and if positional slippage of the belt-shaped photosensitive body 8 from a standard position in the breadthwise direction is within the allowable limit, the scan optical beam from the scanner 5 is received by the photodetector S2, but it is not received by the photodetector S1 because the scan optical beam is intercepted by the photosensitive body 8. However, if the photosensitive body 8 is displaced in the direction of an arrow L and the positional slippage exceeds the allowable limit, the scan optical beam is received by the photodetector S1 also. If the photosensitive body 8 is displaced in the reverse direction of an arrow R, the scan optical beam is not received by the photodetector S2 neither. Output signals of photodetectors S1 and S2 are inputted to a control means 25 to operate a driving source 26, and a roll displacing mechanism 27 is operated to control the photosensitive body 8 in such direction that the positional slippage is within the allowable limit. |
