| 摘要 |
An apparatus is provided for determining the position of a shaft that is rotatably displaceable about a longitudinal axis. The apparatus includes a source of light energy, first and second light detecting devices that are arranged adjacent the shaft, and a third light detecting device mounted on the shaft. A rotatably displaceable disc having an opening near the disc's perimeter is mounted between the source of light energy and the light detecting devices. A position-determining circuit connected to the light detecting devices measures the time that the light detecting devices are sequentially activated by the light emanating from the disc opening and applies the time so measured to a position-determining scheme. The position-determining scheme uses the time measured and the physical geometry of the apparatus to determine the position of the shaft.
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