| 摘要 |
A detection circuit having a normally open low impedance loop comprised of a step motor coil and a low impedance element, and a normally open high impedance loop comprised of the step motor coil and a high impedance element is used to detect whether or not the step motor has angularly advanced in response to application of a drive pulse to the step motor coil. The detection circuit is driven by alternately switching between the low and high impedance loops to thereby alternately close the loops to enable detection of a voltage induced in the step motor coil indicative of whether or not the step motor rotor has angularly advanced in response to the application of a drive pulse to the step motor coil, and the alternate switching between the low and high impedance loops is controlled so as to prevent occurrence of a condition in which the low and high impedance loops are both open simultaneously during detection of the induced voltage. By driving the detection circuit in this manner, the induced voltage remains more stable, detection errors are avoided, and the integrated circuitry of the detection circuit can be more easily designed and fabricated as no particular consideration need be given to the gate capacitance of the switching transistors of the detection circuit.
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