Patent ID: 7567014

Claim:
An energy trap piezoelectric resonator making use of a harmonic wave in a thickness longitudinal vibration mode, comprising: a piezoelectric substrate having opposing first and second principal surfaces; a first excitation electrode disposed at the first principal surface of the piezoelectric substrate, and a second excitation electrode disposed at the second principal surface of the piezoelectric substrate so as to oppose the first excitation electrode, a portion where the first and second excitation electrodes oppose each other being a piezoelectric vibration portion; and at least one floating electrode disposed at at least one of the first and second principal surfaces of the piezoelectric substrate so as to be arranged near the piezoelectric vibration portion and so as to extend towards and away from the first and second excitation electrodes with respect to a node of an electric potential distribution based on electric charges generated at the first and second principal surfaces of the piezoelectric substrate by a fundamental wave in a thickness longitudinal vibration mode; and the at least one floating electrode includes a vibration damping portion arranged to suppress a fundamental wave in a thickness longitudinal vibration mode.