| 摘要 |
PROBLEM TO BE SOLVED: To provide a positioning structure with respect to a photoreceptor drum capable of maintaining a specified positional relation between a photoreceptor drum and a developing roller. SOLUTION: The photoreceptor drum 11 is held freely rotatably at tube stocks 111 exposed at both end parts by being borne by bearings 126 and 127 provided on drum unit side plates 124 and 125. The developing roller 15 and a sub-roller 16, whose developing roller shaft 128 and sub-roller shaft 129 are received by a pair of side plates opposite to a developing unit housing 130, and held freely rotationally. On the developing roller shaft 128 extending to both sides of the developing roller 15, regulating rollers 135 and 136 are freely rotatably provided respectively. The regulating rollers 135 and 136 are respectively held in contact with respective periphery of the bearings 126 and 127 for holding both ends of the photoreceptor drum 11. In this way, a biting amount of the developing roller 15 with respect to the photoreceptor drum 11 can be maintained constant. |
