GB1374789A - Force measurement systems - Google Patents

Abstract

1374789 Capacitive force transducers W & T AVERY Ltd 29 Dec 1972 [30 Dec 1971] 60625/71 Heading GIN A capacitive force transducer comprises first and second spaced-apart capacitance plates 33, 34 and a third resiliently-deformable capacitance plate 32 mounted between the first and second plates, the third plate being connected to a force receiver so as to deflect relative to the first and second plates in response to application of a force, and the third plate being constructed so that at least the major part of the applied force is counterbalanced by the inherent spring resistance of the third plate. As shown, the third plate is constituted by a ceramic diaphragm spring the inner portion 37 of which is provided on opposite faces with annular electrodes 35, 36 which co-operate with the fixed first and second annular plates 33, 34. The force is applied to the spring 32 by a tie rod 31. The arrangement is immersed in dielectric liquid, e.g. liquid paraffin. The ceramic material may be alumina or silicon nitride. Electrical resonant circuits including a coil 42, a transistor 43 and a capacitor 44 are provided.