| 摘要 |
PURPOSE:To prevent erroneous operation due to rotary vibration, by providing a pair of FFs for latching one of output of a pair of sensors, of which the phases are shifted by a predetermined angle, by the other output at the incremental and decremental edges of one output. CONSTITUTION:A pair of sensors 11, 12 provided to the outer peripheral part of a rotor 10 output detection pulses (a), (b), of which the phases are shifted by 90 deg., with the rotation of the rotor 10. The pulse (a) is supplied to FFs 13, 14 as data and the pulse (b) is supplied to FF13 as it is and supplied to FF14 as a clock pulse in a reversed state. Therefore, FF13 latches the pulse (a) at the incremental edge of the pulse (b) and FF13 latches the same at the decremental edge of said pulse (b). The outputs of FFs 13, 14 are supplied to an exclusive OR gate 15 and the pulse (a) is supplied to a counter 17 only when the outputs of FFs 13, 14 are different. By this method, erroneous operation due to rotary vibration can be prevented.
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