PHOTOELEKTISCHER SCHALTER

摘要

A photoelectric switch having a rectifier for converting a received AC voltage to a DC voltage, a transparent cover having a user friendly finger rest surface, means for generating a pulsed infrared beam across the finger rest surface, means responsive to the breaking of the pulsed infrared beam by an operator placing at least one finger on the finger rest surface to actuate a relay to generate an output signal, and means for disabling the actuation of the relay in response to the operator removing his finger from the finger rest surface restoring the continuity of the pulsed infrared beam. The photoelectric switch includes fault protection circuits which disable the relay when the AC voltage is below a predetermined voltage, when the ambient infrared background illumination exceeds a predetermined value, or when the means for generating a pulsed infrared beam fails to generate the beam. The photoelectric switch also includes circuits for lighting a fault light when the AC voltage is less than the predetermined voltage, the ambient infrared background illumination exceeds the predetermined limits, and when a contact in the relay welds or becomes stuck in the activated position.