| 摘要 |
PURPOSE:To enhance the catch detecting function by converting a waveform from a pulse encoder attached to a motor into a triangular waveform, and by comparing the same with a smoothened reference waveform. CONSTITUTION:Upon catching, the speed of a motor 20 lowers, and accordingly, the pulse width of waveforms delivered from a pulse encoder 44 becomes large. Accordingly, the voltage of triangular waveforms formed by a waveform converting circuit 50 gradually increases at a constant variation rate. Then, the triangular waveforms are smoothened by a smoothing circuit composed of a resistor 66, a capacitor 70, an amplifier 68 and the like, and accordingly, the voltage of a reference waveform is also raised. In this case, since the voltage rise-up variation rate of the reference waveform is smaller than that of the triangular waveforms, the voltage of the triangular waveforms is higher than that of the reference waveform. Further, a difference detecting comparator 62 delivers a high level signal to a motor operation logic circuit 42 so that the motor 20 is stopped and reversed. With this arrangement, the detection can be made with a high degree of accuracy, and a catching load can be reduced. Further, it is possible to eliminate the necessity of limitation to the detection processing speed. |
