Multifunction steering wheel

Claim 1

A multifunction steering wheel for controlling the operation of devices disposed on a vehicle having a steering column comprising: steering wheel member rotatably carried on said steering column and having a hollow spokelike arm; manually actuable hermetically sealed keypad disposed on said steering wheel member, said keypad comprising a plurality of individual switches connected in a matrix configuration; a transmitter module disposed within said arm and coupled to said switches, said transmitter module having encoder means for providing strobe signals to said switching and having an input bus coupled to said switches for interrogating said switches, said encoder means further having an output means for providing predetermined encoded output pulses in response to activation of said switches; said transmitter module having transistor driver circuit comprising a first transistor having the base thereof coupled to said output means of said encoder and comprising a second transistor having the base thereof coupled to the emitter of said first transistor and said first and second transistors having their respective collectors coupled together to provide an output node; said transmitter module further having a current limiting circuit comprising load resistor coupled between the emitter of said second transistor and ground and comprising a third transistor having the base thereof coupled to said load resistor and having the emitter thereof coupled to ground and having the collector thereof coupled to the base of said first transistor and further having second resistor coupled between the collector of said third transistor and ground; said current limiting circuit being operable to sense the collector current of said first transistor and to turn off said first transistor to prevent excessive current flow; a plurality of mutually connected light emitting diodes coupled to said output node of said driver circuit for producing light impulses in accordance with said output pulses, said light emitting diodes being equally spaced about a circular locus and positioned to direct illumination toward said steering column; a receiver module positioned within said steering column, said receiver module including a phototransistor mounted to receive illumination from said light emitting diodes, and further including amplifier circuit capacitively coupled to said phototransistor for providing amplified signals in accordance with said output pulses; a decoder module positioned within said steering column and receptive of said amplified signals, said decoder module providing a plurality of input/output ports for providing a binary signals indicative of said encoded output pulses, said decoder module further including binary to decimal decoder means for receiving said binary signals and providing a plurality of individual output terminals, each terminal corresponding to a different one of said devices disposed on a vehicle; and at least one flip flop means coupled to said output terminals for controlling at least one of said devices.