Patent ID: 7726209

Claim:
A force or pressure sensor, comprising: a substantially rigid, mechanical-load resistant frame, a flexible diaphragm having an user and a lower surface, said flexible diaphragm being secured to the frame, and a piezoelectric ceramic sensor diaphragm applied to the lower surface of the flexible diaphragm, and a substantially rigid cover for loading the sensor diaphragm and capable of carrying mechanical loading of more than 50 kg, wherein the cover includes a protrusion or shoulder bearing against a middle section of the upper surface of the flexible diaphragm and thus, by deflection, prestressing the flexible diaphragm and the piezoelectric ceramic sensor diaphragm attached therebelow, a sensor-signal transmitting conductor disposed in contact with the piezoelectric ceramic sensor diaphragm opposite to a location of the cover protrusion or shoulder bearing against the middle section of the upper surface of the flexible diaphragm, and wherein the frame and the cover define therebetween a closed housing chamber, the flexible diaphragm and the piezoelectric ceramic sensor diaphragm being located thereinside, wherein the flexible diaphragm has a peripheral rim extending between mating edges of the frame and the cover such that the peripheral rim is fixedly secured therebetween, wherein the piezoelectric ceramic sensor diaphragm comprises a piezoceramic diaphragm having a diameter smaller than a diameter of the flexible diaphragm such that the piezoceramic sensor diaphragm has a peripheral rim spaced inwardly a distance from an inner periphery of the housing chamber, wherein the frame, the cover and the diaphragms are rotationally symmetrical relative to the cover protrusion or shoulder.