Abstract 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.
In an avionics system having a compass card and a manually movable heading select indicator therein, the improvement comprising a shutter, a light source, a light sensitive detector, said detector having an electrical signal output therefrom, a cam surface oPeratively coupled to said compass card said surface contacting said shutter, means for moving said cam surface in accordance with the relative angular positions of said heading select indicator and said compass card, and means for movably mounting and locating said shutter between said light source and said light sensitive detector to thereby preclude at least a portion of said light from impinging on said detector when said shutter occupies a preselected position, said detector signal output corresponding to the angular position of said heading select indicator with respect to said compass card.
Claim 2
Dependent Claim
132 words
In an avionics system having a compass card and a manually movable heading select indicator therein, the improvement comprising a shutter, a light source, a light sensitive detector, said detector having an electrical signal output therefrom, a cam surface oPeratively coupled to said compass card said surface contacting said shutter, means for moving said cam surface in accordance with the relative angular positions of said heading select indicator and said compass card, and means for movably mounting and locating said shutter between said light source and said light sensitive detector to thereby preclude at least a portion of said light from impinging on said detector when said shutter occupies a preselected position, said detector signal output corresponding to the angular position of said heading select indicator with respect to said compass card.
Claim 3
Dependent Claim
51 words
The combination as in claim 1 wherein said system includes a bridge circuit, said detector being located within said bridge circuit and operable to effect a bridge circuit output correlated to the angular movement of said heading select indicator when said shutter variably impedes the illumination of said light sensitive detector.
Claim 4
Dependent Claim
90 words
The combination as in claim 2 wherein said bridge circuit includes at least two light sensitive detectors, said shutter being positionable so that an amount of light from said light source impinges upon each of said light sensitive detectors to effect the balancing of said bridge circuit, said shutter operable to be moved in accordance with the movement of said heading select indicator to permit more light to impinge upon one detector than on the other, said bridge circuit thereby having an error signal output corresponding to said indicator movement.