| 摘要 |
PURPOSE:To effectively prevent an oscillation of a rotor by averaging detected rotating speed information of the rotor, first, second rotating speed information stored in memory means at the time of forming a picture, and controlling rotor driving means based on averaged rotating speed information. CONSTITUTION:A color picture forming apparatus rotates a plurality of photosensitive drums by a common drive motor (stepping motor) 15 through a gear train. A rotary encoder (RE) 21 and an RE 22 for correcting the RE 21 at the time of regulating before a delivery from a factory are provided on a rotary shaft of the drum, and their detection signals are input to a CPU 23. When the motor 15 is driven at a predetermined speed, pieces of rotating speed information by the REs 21, 22 are stored in a RAM 25 at respective predetermined divided zones, and rotating speed information detected by the RE 21 and the pieces of the stored rotating speed information by the REs 21, 22 at the time of forming a picture are averaged. The motor 15 is controlled based on the averaged information. |
