| 摘要 |
PROBLEM TO BE SOLVED: To avoid motor step out due to rapid torque change in switching, eliminate the necessity of previously increasing the dimensions of a motor for avoiding the motor step out, due to rapid torque change and stably control switching, for a color image-forming device, which has a control drive circuit driving a transfer drum or a middle transfer drum by a step motor, so as to eliminate misregistration of each color and performs excitation switch by using a beam-detecting circuit. SOLUTION: In accelerating/decelerating of a transfer drum or a intermediate transfer drum, a timer circuit 9 which outputs a pulse other than a beam detection signal (BD) 4 (acceleration pulse or deceleration pulse) is used for smoothly accelerating or decelerating a motor 7. When an excitation switch cycle becomes close to the cycle of the beam detection signal (BD) 4, a switch 12 is turned to an (a) side by a pulse input switch control circuit 11, so as to switch to the constant speed rotation by using the beam detection signal (BD) 4. |
