Digital output force sensor using surface acoustic waves

Abstract From the Canadian patent

A sensor developing a digital output in response to force induced deflection in which the deflection is of a beam formed to have, under stress, a surface undulate in both compression and tension. The signal is developed from piezoelectric transducers connected in a pair of oscillator circuits utilizing surface acoustic wave paths through respectively, the tension and the compression portions of the beam surface. The frequencies of the oscillators are compared and the frequency difference resulting from beam deflection is sent as a signal to a counter to give a digital read out of the force causing the deflection. The beam is formed of steel and the piezoelectric surface for the surface …