| 摘要 |
PROBLEM TO BE SOLVED: To make a driving force for a holding means small, to reduce the cost of a power source, and also to increase the speed of image formation by providing one fixedly-arranged developing unit and a plurality of developing units which are selectively provided for development by the holding means. SOLUTION: Opposing to a photoreceptor 7, a first developing unit 10 filled with black toner is fixed to a frame. A freely movable developing mechanism 11 is equipped with the three developing units, second-fourth developing units 22-24, using, for example, yellow toner, and the developing units are disposed on a movable base 25 as the holding means and selectively moved to a second developing position 32. In the illustration, the second developing units 22 are in the second developing position 32, and they are about to be moved close to and opposite the photoreceptor 7 by a rising/lowering means. The movable base 25 moves by means of a stepping motor 27 and, out of the second-fourth developing units 22-24, requested one is moved to the second developing position 32 which is opposite to the photoreceptor 7. |
