Patent ID: 7414349

Claim:
A piezoelectric vibrator comprising: a piezoelectric plate, having a polarization that points in a direction of a thickness of the piezoelectric plate, the piezoelectric plate having a first face and a second face; a first electrode for covering the first face; a second electrode for covering the second face; a first dielectric film for covering the first electrode; and a second dielectric film for covering the second electrode, wherein the piezoelectric plate employs a thickness longitudinal vibration as a principal vibration, the first dielectric film and the second dielectric film have substantially a same thickness, a substantially same area, and a substantially same geometric shape, a ratio of a sum of a thickness (ts) of the first dielectric film and the second dielectric film to the thickness (tp) of the piezoelectric plate is provided in a range such that an electromechanical coupling factor is substantially constant, wherein the range of the ratio (ts/tp) is between 0.7 and 2.0, inclusively.