Patent ID: 6232698
Filing Date: 2001-05-15
Classification: H03H

Abstract:
An energy-trap thickness extensional vibration mode piezoelectric resonator utilizing an nth-order harmonic of a thickness extensional vibration mode, comprising:a piezoelectric plate having first and second surfaces arranged opposite to each other;a first excitation electrode provided on said first surface of said piezoelectric plate;a second excitation electrode provided on said second surface of said piezoelectric plate and arranged opposite said first excitation electrode with said piezoelectric plate disposed therebetween;at least one internal electrode disposed in said piezoelectric plate and located at least partially opposite to the first and second excitation electrodes;an opposing portion of said first and second excitation electrodes, said internal electrode and said piezoelectric plate defining a resonating portion, such that said first excitation electrode, said second excitation electrode and said at least one internal electrode extend across substantially the entire width of said piezoelectric plate;vibration-attenuating portions disposed on only two sides of said resonating portion along the longitudinal direction of the piezoelectric plate;said first and second excitation electrodes extending substantially to both sides of the piezoelectric plate in a direction that is substantially perpendicular to said one direction in which said vibration-attenuating portions extend; andsaid first and second excitation electrodes overlapped with said internal electrode only at a central portion of said piezoelectric plate and over a length of l such that l/d.ltoreq.6 in which d=t/n, where t is a thickness of said piezoelectric plate and n is an integral larger than 1.