Patent ID: 7977851

Claim:
Push button switch comprising: a piezoelectric element ( 10 ) which is arranged between a first electrode ( 16 ) and a second electrode ( 18 ) such that, when a pressure is exerted on the piezoelectric element, an electrical voltage is generated between the first and the second electrode ( 16 , 18 ), wherein an amplifier circuit ( 20 ) has a first input which is connected to the first electrode ( 16 ) of the piezoelectric element ( 10 ) and a second input which is connected to the second electrode ( 18 ) of the piezoelectric element ( 10 ); the amplifier circuit ( 20 ) is operated by a voltage source ( 22 ) and generates at the output thereof an amplified voltage between the first and the second electrode of the piezoelectric element as a measurement signal (Uout); and connected between one of the first and the second electrodes ( 16 , 28 ) of the piezoelectric element ( 10 ) and a reference point ( 24 ) of the voltage source ( 22 ) of the amplifier circuit ( 20 ) is an additional voltage source ( 26 ) having an operating voltage (Ub) which is greater than the maximum voltage between the first and the second electrode ( 16 , 18 ) of the piezoelectric element ( 10 ).