| 摘要 |
PURPOSE:To correct offset, thread, etc. arising on an endless belt member by detecting marks in the lateral direction with respect to the moving direction of the endless belt member and changing the relative position of a belt holding mechanism based on an output signal from the detecting means. CONSTITUTION:The marks a2 and b3 are provided in the position on the outer periphery of the belt 1; the position practically bisects the peripheral length of the belt 1 in its moving direction offsetting the belt 1. The belt 1 is provided with a mark reader 130. When the belt 1 is offsetting, photodetector, not one specific photodetector, outputs an electrical signal showing that marks a2 and b3 are detected whenever the belt 1 makes one turn. Thus, trouble such as offset and thread arising on the belt member 11 can be corrected without applying load to the endless belt member 11. |
