Piezoelectric sensor with FET amplified output

Claim 1

A sensor for the measurement of dynamic force, pressure or acceleration comprising: a sensor body having a mass portion and a base portion; a first and second layer of piezoelectric crystals disposed between said sensor body mass and base portions and coaxially disposed with respect to each other for generating a voltage signal; a first electrode separating said first and second crystal layers; a second electrode of U-shaped configuration in cross section retaining said crystal layers and said first electrode between opposing surfaces of said electrode configuration in a sandwiched unity structure; electrical insulative material disposed between said second electrode and said sensor body mass and base portions; amplifying means operatively coupled between said first and said second electrodes responsive to said voltage signal whereby the effect of crystal capacitance is cancelled by reducing the voltage potential across said crystal layers; said amplifying means includes a field effect transistor circuit constituting an integral unity gain, impedance converting amplifier having a source connection and a gate connection; said first electrode operably coupled to said transistor circuit gate connection and said second electrode operably coupled to said source connection of said transistor circuit.