| 摘要 |
PURPOSE:To prevent the unevenness of image density from occurring because a developing sleeve is deformed by heat from a photosensitive drum heated by a heater while image forming operation is stopped. CONSTITUTION:At least two developing sleeves 15 and 17 are installed to be opposed to the photosensitive drum 3 incorporating the heater. A difference (beta-alpha) between an angle alpha obtained by rotating either developing sleeve 15 until an optional point R on the photosensitive drum 3 moves to a 1st position A where the sleeve 15 and the drum 3 are the most proximate to each other, and an angle beta obtained by rotating the other developing sleeve 17 until the optional point R on the drum 3 moves to a 2nd position B where the sleeve 17 and the drum 3 are the most proximate to each other is (2pi/S)Xk(radian). Provided that S means the number of the sleeves, and (k) means an integer except the multiple of S. |
