Kapazitiver Schalter

摘要

The switch has a capacitive probe with a sensor electrode (11) and a screening electrode (12) and an electronic circuit with an oscillator provided by a pair of operational amplifiers (16,15) connected in a feedback configuration. One of the amplifiers acts as a difference amplifier and the other acts as a voltage follower, the sensor electrode coupled to the inverting input of the difference amplifier (15) which has a capacitor (18) connected in its feedback circuit. A variable part of the output of the difference amplifier is fed to the non- inverting input of the voltage follower amplifier (16), providing an output fed to the non-inverting input of the difference amplifier, to which the screening electrode is coupled.