Piezoelectric load cell for differential measurements - has pair of matched crystal plates with one attached to pressure diaphragm, and second used as reference

摘要

The piezo-electric load cell for differential force or pressure measurements comprises a cylindrical container in which are mounted two vertical, parallel, circular crystal discs (2, 3). The lower edge of each crystal plate sits in an insulated socket (4) and electrical leads connect each crystal to terminals on the outside of the case and to an oscillator. The upper edge of each plate is held in a similar seating, each being independently suspended by means of flat springs (5, 6) and flexible diaphragms (7, 8). The upper diaphragm has a central plunger (14) which passes through the centre of the spider of the second suspension system. This plunger transmits the diaphragm movement to the measuring crystal, the other crystal being used as a reference.