Patent ID: 8693212

Claim:
A chassis for storing in an interior of the chassis electrical components, such chassis having a cover moveable between an open position and a closed position and circuitry for detecting whether the cover is in the open position or the closed position, such circuitry comprising: a transmitter of light disposed at a fixed position within the chassis, such transmitter transmitting light as a train of pulses at a predetermined frequency; a receiver for light disposed at a fixed position within the chassis; a reflector mounted to an inner surface of the cover, such reflector being disposed in a path to intercept and then reflect intercepted transmitted light to the receiver when the cover is moved to the closed position and being disposed away from the path to prevent the transmitted light to be intercepted and then reflected to the receiver when the cover is moved to the open position; and wherein the receiver includes a frequency detection circuit for indicating whether the cover is in either the open position or the closed position selectively in accordance with whether the transmitted light is reflected to and received at the receiver at the predetermined frequency of the train of pulses.