Composite piezoelectric transducer and resonator - has one or more piezoelectric plates soldered on each face of metal strip, opposing plates being staggered wrt one another

摘要

A piezoelectric resonator or transducer device resonant in a single mode comprises a metal strip (2) of, for e.g an alloy such as Durinvol (RTM), Elinvar (RTM) or Thermelast (RTM) with a respective piezoelectric plate (4,6) covering half of the upper and lower surface of the strip, the plates extending from opposite ends of the strip. Each plate is metallised with e.g Ni-Cr-Au to allow electrical connection to one of two terminals (10,12), the other being connected to the strip. With a piezoelectric plate of lithium niobate 0.5mm thick, 22mm long and 3mm wide on a 3mm thick strip 44mm by 3mm and 1 micrometre thick metallisation a resonant frequency of 55 KHz in a lengthwise mode is obtd. without parameter degradation. A bending mode function provides a resonant frequency of 8KHz.