Abstract: A crystal resonator includes a flat plate-shaped crystal element and excitation electrodes. The crystal element has principal surfaces parallel to an X?-axis and a Z?-axis. The X?-axis is an axis of rotating an X-axis in a range of 15 to 25 degrees around a Z-axis. The Z?-axis is an axis of rotating the Z-axis in a range of 33 to 35 degrees around the X?-axis. The excitation electrodes are formed on the respective principal. The excitation electrodes include a first region with a circular outer shape and a second region. The second region is formed at a peripheral area of the first region. The second region has a thickness thinner than the first region and has an elliptical outer shape. The elliptical shape has a long axis extending in a direction in a range of ?5 to +15 degrees with respect to a direction that the X?-axis extends.

Abstract: A crystal resonator includes a crystal element and excitation electrodes. The crystal element has a pair of principal surfaces parallel to an X?-axis and a Z?-axis. The X?-axis is an axis of rotating an X-axis as a crystallographic axis of a crystal in a range of 15 degrees to 25 degrees around a Z-axis as a crystallographic axis of the crystal. The Z?-axis is an axis of rotating the Z-axis in a range of 33 degrees to 35 degrees around the X?-axis. The excitation electrodes are formed on the respective principal surfaces of the crystal element. Elliptical mesa portions or elliptical inverted mesa portions are formed on the respective principal surfaces. The mesa portions project from outer peripheries of the principal surfaces. The inverted mesa portions are depressed from the outer peripheries of the principal surfaces.

Abstract: A crystal resonator includes a crystal element and excitation electrodes. The crystal element has a pair of principal surfaces parallel to an X?-axis and a Z?-axis. The X?-axis is an axis of rotating an X-axis as a crystallographic axis of a crystal in a range of 15 degrees to 25 degrees around a Z-axis as a crystallographic axis of the crystal. The Z?-axis is an axis of rotating the Z-axis in a range of 33 degrees to 35 degrees around the X?-axis. The excitation electrodes are formed on the respective principal surfaces of the crystal element. Elliptical mesa portions or elliptical inverted mesa portions are formed on the respective principal surfaces. The mesa portions project from outer peripheries of the principal surfaces. The inverted mesa portions are depressed from the outer peripheries of the principal surfaces.

Abstract: A crystal resonator includes a flat plate-shaped crystal element and excitation electrodes. The crystal element has principal surfaces parallel to an X?-axis and a Z?-axis. The X?-axis is an axis of rotating an X-axis in a range of 15 to 25 degrees around a Z-axis. The Z?-axis is an axis of rotating the Z-axis in a range of 33 to 35 degrees around the X?-axis. The excitation electrodes are formed on the respective principal. The excitation electrodes include a first region with a circular outer shape and a second region. The second region is formed at a peripheral area of the first region. The second region has a thickness thinner than the first region and has an elliptical outer shape. The elliptical shape has a long axis extending in a direction in a range of ?5 to +15 degrees with respect to a direction that the X?-axis extends.

Abstract: A crystal resonator includes a flat plate-shaped crystal element and excitation electrodes. The crystal element has principal surfaces parallel to an X?-axis and a Z?-axis. The X?-axis is an axis of rotating an X-axis as a crystallographic axis of a crystal in a range of 15 degrees to 25 degrees around a Z-axis as a crystallographic axis of the crystal. The Z?-axis is an axis of rotating the Z-axis in a range of 33 degrees to 35 degrees around the X?-axis. The excitation electrodes are formed on the respective principal surfaces of the crystal element. The excitation electrodes are each formed into an elliptical shape. The elliptical shape has a long axis extending in a direction in a range of ?5 degrees to +15 degrees with respect to a direction that the X?-axis extends.