MOTOR ROTARY PULSE GENERATING CIRCUIT OF DC MOTOR AND CATCH DETECTION DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To generate accurate pulses matching motor rotation by preventing generation of abnormal pulses even if the speed of a dc motor is delayed and to achieve accurate catch detection in detecting catch on the basis of the motor current of the dc motor by using a circuit generating the pulses. SOLUTION: A low-pass filter LPF including a low frequency filter FL1L and a high frequency filter FL1H eliminates noises and a first differentiating circuit DC1 differentiates an output of the low pass filter LPF to attenuate dc components. A first amplifier AP1 amplifies an output of the first differentiating circuit DC1 and a second differentiating circuit DC2 differentiates an output of the first amplifier AP1 and shifts its phase. A comparator CM compares an output of the second differentiating circuit DC2 with an output of the first amplifier DC1 and the low frequency filter FL1L and the high frequency filter FL1H are switched from one to the other to give a variable shutoff frequency.