| 摘要 |
PURPOSE:To prevent damage of a component of a motor lock, etc., by controlling a rotating speed of a motor for driving an optical system by a pulse-width modulation of a motor driving current, comparing a duty ratio of a pulse-width modulation signal with a reference value, and judging a malfunction of a driver. CONSTITUTION:When a speed of a motor 38 for driving an optical system in a copying machine is controlled, ON/OFF command of a rotating speed of the motor 38 is output from a slave CPU 51, and the motor 38 is controlled by a speed controller 61 through a driving circuit 62. In this case, a rotating speed signal from a rotary encoder RE is compared with a reference clock signal by a speed discriminator 65 in the controller 61 to detect a speed error, and the error is converted to a speed control voltage by a charge pumping circuit 66. The control voltage is converted to a pulse-width modulation signal by a PWM circuit 68, and its duty ratio is compared with a threshold value. When the duty ratio exceeds the threshold value, a malfunction of a driver is judged to stop an operation of the optical system. |
