Patent ID: 8026652

Claim:
A quartz crystal resonator element, comprising: an AT-cut quartz crystal substrate, the substrate having edges parallel to each of a Z″ axis obtained by rotating a Z′ axis in a range of −120° to +60° about a Y′ axis and an X′ axis perpendicular to the Z″ axis when an angle formed by rotating a +Z′ axis in a direction of a +X axis about the Y′ axis is a positive rotation angle; a thin section that forms a resonating section; and a thick section adjacent to the resonating section, the thin section and the thick section being formed on the quartz crystal substrate by wet etching, wherein the thin section is formed either on a main surface of the substrate corresponding to a +Y′-axis side or on a main surface of the substrate corresponding to a −Y′-axis side; and when the thin section is formed by the etching on the main surface of the +Y′-axis side, the thick section is provided at at least a +Z″-axis-side end of the thin section, whereas when the thin section is formed by the etching on the main surface of the −Y′-axis side, the thick section is provided at at least a −Z″-axis-side end of the thin section.