Procedure for operating an ultrasonic approach switch and an ultrasonic approach switch with operational optimisation

摘要

The proximity switch (1) has an ultrasonic transducer (2), a processing unit (3) and microprocessor (4). The processing unit has an amplifier (5), filter (6), demodulator (7) and comparator (8) all serially connected. The amplifier is at the input (9) of the processing unit and the comparator at its output. A feedback loop feeds to the amplifier via a control loop with a variable gain amplifier (19). The output (12) of the ultrasonic transducer is connected to the amplifier at the input of the processing unit. The output of the processing unit lies at the input (13) of the microprocessor which has a parameter interface (14). A series connection of an oscillator (16) and transmit end stage (17) is connected between the microprocessor output and the input.