Patent ID: 8536761

Claim:
A piezoelectric resonator comprising: a piezoelectric plate in which thickness-shear vibration is principal vibration and which has a vibrating portion that is surrounded by a peripheral portion and has a larger thickness than the peripheral portion; and an excitation electrode disposed on a principal surface of the piezoelectric plate, wherein both a long side of the vibrating portion and a long side of the excitation electrode are parallel to a long side of the piezoelectric plate, assuming that a long side length of the piezoelectric plate is X, a thickness of the vibrating portion is t, a long side length of the vibrating portion is Mx, a long side length of the excitation electrode is Ex, and a wavelength of flexure vibrations occurring in a longitudinal direction of the piezoelectric plate is λ, the relationship of λ/2=(1.332/f)−0.0024 (where, f is a resonance frequency of a piezoelectric resonator), (Mx−Ex)/2=λ/2, Mx/2={(A/2+(1/4)}λ (where, A is a positive integer), and X≧20t is satisfied, a protruding portion, which is disposed on an extension line of the vibrating portion in the longitudinal direction so as to be parallel to a short side direction of the vibrating portion, is provided, assuming that a length of the protruding portion in the displacement direction of the principal vibration is Dx, the relationship of Dx=(λ/2)×m (where, m is a positive integer) is satisfied, and assuming that the distance between the vibrating portion and the protruding portion is Sx, the relationship of Sx=(λ/2)×n±0.1λ (where, n is a positive integer) is satisfied.