| 摘要 |
PURPOSE:To switch and set the revolving speed of a cooling fan at a standby time according to the load of the fan side so that generated noise becomes the minimum. CONSTITUTION:In the case that a motor M is hardly rotated through a driving current is supplied to the motor M when the cooling fan for introducing cooling air to the inside of an image forming device is rotated at a low speed, a voltage value flowing to a lock detection part becomes H by the actuation of a sensor incorporated in the motor M. Therefore, it is decided by a CPU 13 that the motor M is under a state of locking and unsufficient impressing voltage by PWM control because the load of the motor side is large. Then, the fan motor M is driven by a transistor Tr1 for driving a motor by receiving a signal from the CPU 13 and being turned on or off. At this time, the impressing voltage is controlled by the PWM control so as to be increased stepwise. |
