Self checking safety switch

A safety switch for controlling power to a machine, comprising:

• a housing having an opening configured to allow insertion of a human hand into said opening;
• switch circuitry contained within said housing, comprising:
• a primary emitter that emits a detectable signal;
• a primary detector for detecting said detectable signal;
• and
• a self check circuit, coupled to said primary emitter and said primary detector, said self check circuit comprising a secondary detector for detecting said detectable signal emitted from said primary emitter, said secondary detector generating a signal that energizes a secondary emitter, said secondary emitter emitting a signal that is detected by said primary receiver;
• said switch circuitry producing an output signal upon the insertion of said human hand into said opening.

A hand-operated safety switch adapted to actuate a machine to which the switch is coupled when a hand engages the housing, the switch comprising:

• a housing having an opening configured for insertion of a human hand into said opening and switching circuitry contained within said housing comprising;
• a primary light emitting means for emitting a first beam of light along a first light transmission path;
• a primary sensor means being electrically responsive to said first beam of light traveling along said first light transmission path;
• a secondary sensor means being electrically responsive to said beam of light traveling along a second light transmission path from said primary light emitting means wherein said secondary sensor means generates a signal that energizes a secondary light emitting means;
• said secondary light emitting means for emitting a second beam of light along a third light transmission path in response to said signal generated by said secondary sensor;
• said primary sensor means being electrically responsive to said secondary beam of light traveling along said third light transmission path;
• said primary sensor means combining said first beam of light and said second beam of light to produce an output signal that controls actuation of the machine.