| 摘要 |
PROBLEM TO BE SOLVED: To make the abnormality of a motor detectable in an early stage at the time of starting the motor by stopping the power supply to the motor by outputting a low-rotation detecting signal when the both-terminal voltage of a charged capacitor reaches a prescribed value. SOLUTION: The reference voltage 22 of a polygon motor driving device outputs reference voltages Vref1 and Vref2, where the Vref1 is the reference voltage for the specified number of revolutions of a motor 16 plus allowable error and the Vref2 is the reference voltage for the number of revolutions minus allowable error. In addition, the reference voltages Vref1 and Vref2 are respectively inputted to comparators 25 and 24. When the output of an F-V conversion circuit 21 is larger than the Vref1, but smaller than the Vref2, the rotation of the motor 16 becomes high and, when the output is higher than the Vref1 or lower than the Vref2, the rotation becomes low. Upon receiving a detect signal from a low-motor speed detecting circuit 31, an abnormal number-of-rotation detecting circuit 26 discriminates that abnormality occurs in the motor 16, etc., and stops the power supply to a bridge circuit 10 and the motor 16 by forcibly turning off a PWM circuit 22. Therefore, the abnormal number of revolutions of the motor 16 can be detecting in an early stage. |
