| 摘要 |
Apparatus for using an integrated diode array, also called a position sensing detector, which indicates the position of a spot of electromagnetic radiation along a sensitive strip, to measure angular rotation of a stationary shaft from a zero point. A beam of infrared or laser radiation is reflected from a mirror set at an angle other than 90 degrees to the shaft axis, located on a free end of the shaft. The reflected beam falls on the integrated diode array, its position being proportional to the tangent of the angle from the zero point (preferably the center of the sensitive area). The sum of analog voltage signals from both ends of the sensitive area is held constant by second electronic means through feedback monitoring of the radiation source power (beam intensity). In a shaft-angle controlling embodiment, the difference of the two analog voltage signal outputs is adjusted to be equal to a predetermined voltage corresponding to the desired angle using a first electronic means feeding back to whatever rotates the shaft.
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