Safety switch system with photooptical and capacitance detection

摘要

A switch system for an industrial machine is described which combines both optical and capacitance switches in a switch assembly. A photo-optical switch is positioned in each assembly to provide an output signal upon the introduction of a human hand into an opening formed therein, and a capacitance sensitive touch plate switch is positioned within the opening to provide an output signal upon contact by a human hand. Circuitry responds to the substantially simultaneous activation of both the optical and capacitance switches within the switch assembly and produces an output signal. Typically two of such switch assemblies are used to control power to an industrial machine.