| 摘要 |
An optical position detecting unit for detecting the position and speed of a motor, comprising a light emitting element (2) such as an LED working as a light source, a slit (1) for transmitting or reflecting an optical signal from the light emitting element (2) to produce a sinusoidal optical signal for position detecting, and a photodetector (3) such as a photodiode and a phototransistor for converting the sinusoidal optical signal into an electric signal, wherein the optical axis of the light emitting element (2) is tilted an angle theta with respect to the slit (1) to reflect a light from a light source off the reflection surface made of a reflection material of the slit (1), and the reflected light is converted into an electric signal by the photodetector (3) tilted an angle -theta to obtain a reference signal, at the same time, a light passed through the transparent surface of the slit (1) is converted into an electric signal by the photodetector (4) tilted an angle theta to obtain a phase-reversed reversed signal, whereby improving a noise resistance.
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