| 摘要 |
PURPOSE:To prevent the non-uniform deterioration of a photoreceptor and abtain a copied image of uniform density by varying the operation start period of an optical scanning system is accordance with the magnification, and maintaining the leading tip of an electrostatic latent image formed on the photoreceptor constant at all times. CONSTITUTION:In the magnification 1 copying, cam 23 is disposed with the cam 23 shifted relative to cam 22 such that the time required for the cam 23 till it makes microswitch MS2 on since the start of rotation of photosensitive drum 7 may be made longer than the time for the equal size copying. Therefore MS2 is made on later than microswitch MS1, and electromagnetic clutch 29 is stimulated to attract sprocket 27. Rotation of motor M1 is transmitted to pulley 19 via sprockets 15, 27, 34 so that the optical scanning system of shift mirrors 3, 4 starts its return due to the wire 20. Thus, the non-uniform deterioration of the photoreceptor can be prevented in order to abtain the copied image of uniform density by maintaining the leading tip of an electrostatic latent image formed on the photoreceptor constant. |
