JPS6489618A - Pulse count circuit - Google Patents

Abstract

PURPOSE:To detect the rotational angle of a motor over a wide range of rotational speed from a low speed to a high speed with high accuracy by providing an encoder to output the pulse of a frequency to correspond to the rotational speed of the motor and a prescribed fundamental pulse. CONSTITUTION:When a motor 10 is revolved, an encoder 11 outputs pulses PA2 and PB2 to correspond to the revolving frequency and fundamental pulses PA1 and PB2 respectively to direction discriminating circuits 24A and 14A and edge detecting circuits 24B and 14B. The circuits 24A and 14A respectively generate direction signals UD2 and UD1 and the circuits 24B and 14B respectively generate count pulse signals CNT2 and CNT1. Then, the signals are outputted to counters 25 and 15. On the other hand, a speed detecting circuit 31 outputs a switching signal SEL through an AND gate 33 to the counter 15 in correspondence to the signal CNT2. The counters 25 and 15 respectively output outputs Q2 and Q1 to correspond to the rotational angle of the motor in correspondence to the signals UD2 and UD1. Then, a coupling correcting circuit 32 makes the output Q2 to be four-fold and adds the Q1 and the result is outputted as rotational angle quantity Q of the motor.