| 摘要 |
PURPOSE:To enable the detection of the direction of rotation, by extracting two signals from multi-phase signals corresponding to the rotation to detect the time at which both signals will be the same in the polarity. CONSTITUTION:Signals S1 and S2 fetched from among multi-phase signals are applied to input terminals 2a and 2b and 2c and 2d. Then, a NOR circuit 8 detects the section at which both signals S1 and S2 become negative while a NOR circuit 14 does the section at which both the signals become positive. On the other hand, half-wave components of the signals S1 and S2 are applied to a comparator 24 to decide on the polarity of both the signals in a fixed time (=T/2-t1) after the time t1 at which the signals S1 and S2 both become negative and the comparison output is applied to an AND circuit 20 and an AND circuit 22 through an inverter 26. The output of the circuit 20 is applied to a set input S of an RS-FF circuit 28 as means of deciding on the direction of rotation while the output of the circuit 22 done to a reset input R. Then, the non-inversion output Q of the circuit 28 is fetched from an input terminal 30 as the direction of rotation decision signal.
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