| 摘要 |
PROBLEM TO BE SOLVED: To obtain a device high in printing speed without causing irregularities in an image by using a motor as a driving source for a cam making a developing device abut on and separate from a photoreceptor at a specified rate and controlling the separation and contact of the developing device by the rotational angle of each motor. SOLUTION: Two stepping motors 43 and 44 are used as the driving source of abutting cams 15B, 15Y, 15M and 15C, and the separation and contact of the developing devices 7B, 7Y, 7M and 7C is controlled by the number of pulses of the motors 43 and 44. Namely, the abutting cams 15B, 15Y, 15M and 15C are respectively coaxially provided with driving gears 50B, 50Y, 50M and 50C, and rotational driving force is given to the gears 50B and 50Y from the motor 43 and to the gears 50M and 50C from the motor 44, respectively. In the case of improving printing speed in a two-color or three-color printing mode, development is performed without making the developing device which is not concerned in the development abut on the photoreceptor belt 1 as long as two motors are used for driving whatever two colors and three colors are selected. |
