| 摘要 |
<p>An optical transducer in an avionics system which includes a compass card for indicating aircraft heading has a disc with a cam surface thereon that is rotated by a shaft connected compass card. When a pilot rotates the heading select indicator associated with the compass card to a new heading, the cam surface pivots a shutter in an appropriate direction. A pair of photoresistors are located in a bridge circuit and are equally illuminated by a corresponding light source when the heading select indicator and the aircraft lubber line coincide thereby effecting a predetermined output from the bridge circuit. Shutter movement, due to a heading or course change, causes either one or the other of the two resistors to have a more or less light impinging thereon thereby producing a bridge error signal. The error signal output may then be used by a flight director or auto pilot to maneuver the aircraft to the newly selected heading. Once the heading select indicator and the aircraft lubber line are aligned, the shutter is re-located so that the photoresistors are again in balance and no error signal output emanates from the bridge circuit.</p> |
