Quartz crystal element made of double-rotation y-cut quartz crystal plate

Abstract

A crystal element has a crystal blank which is cut from a crystal of quartz and has a principal plane orthogonal to a Y″-axis, where the Y- and Z-axes are rotated by an angle of α around the X-axis in the crystal to be designated as the Y'- and Z′-axes, and the X- and Y′-axes are rotated by an angle of β around the Z′-axis to be designated as the X′- and Y″-axes. The crystal blank has mutually orthogonal two null stress-sensitivity axes. In the crystal blank, the thickness of the center part at which two null stress-sensitivity axes intersect is increased, and a ridge line portion defining a quadrangular pyramid like shape from the center part toward the outer peripheral part is formed. The sectional thickness of the crystal blank along the base thereof is larger in the central region and becomes gradually smaller toward both ends.