| 摘要 |
The apparatus senses the absolute elevation and azimuth of a device, such as a gun in an arcade target shooting game. The gun is fixed to a shaft which is pivotable about horizontal and vertical axes and which is connected by two linkage assemblies, respectively, to two rotatably mounted encoder plates for rotating them, respectively, in response to pivoting of the gun about the two axes. Each plate has a plurality of apertures arranged in seven concentric rings in accordance with the Gray code, the arcs respectively intercepting seven light beams which are directed to seven photodetectors. At different rotational positions of the plate, different ones of the detectors will sense light. The apertures are arranged to produce discrete coded indications of each one-degree increment of movement of the gun over a range of about 90 DEG .
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