Automatic extraneous light compensation, in the case of infrared -, in the form of proximity detectors

摘要

External-light influences often cause faulty switching in infrared proximity switches. In particular, high-frequency-modulated infrared light proximity switches are caused to rattle by incandescent lamps. This can be suppressed by negative feedback on the phototransistor by means of a capacitor (Cg) and a resistor (Rg). These parallel-connected elements (Cg, Rg) constitute a high-pass filter which passes the high-frequency-modulated transmitted signal. IMAGE