Automatic control device for motor vehicle's windscreen wiper - adjusts wipe timing by boosting operational amplifier gain through feedback resistance switching in conjunction with lamps.

摘要

A rain detector (13) incorporating, e.g. a piezoceramic transducer, is connected through an input resistance (14) to the operational amplifier (16) which drives the interval timing circuit (17) of the wiper motor (12). The feedback loop of an operational amplifier contains two fixed resistances (24,25) switched (26) to increase the gain and sensitivity when the dipped headlamps or parking lamps (29) are switched-on (31). The gain-switching circuit includes an RC interference filter (32) and opt. a speeding-up capacitor (33). ADVANTAGE - Wiping interval can be adapted automatically to different conditions of daytime, dusk and night driving.