Abstract: A piezoelectric device includes a conductive adhesive, a container, and an AT-cut crystal element. The AT-cut crystal element has at least one side surface intersecting with a Z?-axis of the crystallographic axis of the crystal constituted of three surfaces. When a dimension of a straight-line portion along the Z?-axis of a second side opposed to the first side is expressed as W1 and a dimension along the Z?-axis of the AT-cut crystal element is expressed as W0, W1/W0 is 0.91 or greater, and the straight-line portion has both sides constituting corner portions in approximately right angles with sides along an X-axis of the crystal of the AT-cut crystal element. The side of the first side is at a ?X-side in an X-axis of the crystallographic axis of the crystal and a side of the second side is at a +X-side in the X-axis.

Abstract: A crystal unit includes an AT-cut crystal element that has a planar shape in a rectangular shape and a part as a thick portion. The crystal element includes a first end portion, a depressed portion, the thick portion, and a second end portion in this order from a side of one short side in viewing a cross section taken along a longitudinal direction near a center of the short side. The depressed portion is a depressed portion disposed from the thick portion toward the first end portion side, depressed with a predetermined angle ?a and subsequently bulged, and connected to the first end portion.

Abstract: A crystal resonator vibrates in a thickness-shear mode. The crystal resonator includes excitation electrodes being disposed on a front surface and a back surface of a crystal element. The excitation electrodes are disposed on the crystal element to have a positional relationship, where a displacement distribution at an edge of the excitation electrode on the front surface is identical to a displacement distribution at an edge of the excitation electrode on the back surface.

Abstract: A crystal unit includes an AT-cut crystal element that has a planar shape in a rectangular shape and a part as a thick portion. The crystal element includes a first end portion, a depressed portion, the thick portion, and a second end portion in this order from a side of one short side in viewing a cross section taken along a longitudinal direction near a center of the short side. The depressed portion is a depressed portion disposed from the thick portion toward the first end portion side, depressed with a predetermined angle ?a and subsequently bulged, and connected to the first end portion.

Abstract: A piezoelectric vibrating piece includes a vibrating piece body including a vibrator and at least one pair of excitation electrodes formed on a front surface and a back surface of the vibrator. The vibrating piece body is a twice rotated quartz-crystal vibrating piece. The pair of excitation electrodes are arranged in a Z??-axis direction determined by an X??-axis and obliquely disposed with respect to the Y?-axis direction. The X??-axis is rotated by 260° to 300° counterclockwise about a Y?-axis using a +X?-axis direction as a reference. The pair of excitation electrodes are formed to have respective semicircle shapes including straight line portions extending in the X??-axis direction and to be disposed in a state where the straight line portions overlapping with one another. The straight line portion of the excitation electrode includes an inclined portion that gradually decreases in thickness toward an end portion of the excitation electrode.

Abstract: An AT-cut crystal element includes a crystal element having two side surfaces (namely, a Z?-surface) intersecting with a Z-axis of a crystallographic axis thereof. At least one of the two side surfaces is constituted of three of first to third surfaces. The first to the third surfaces meeting following conditions: the first to the third surfaces intersect with one another in this order and formed by rotating a principal surface of the crystal element by predetermined angles; and expressing the angle of the first surface as ?1, a length of the first surface as D, a thickness of a part of the crystal element having the principal surface as t, and M=D/t, and a conversion percentage as fn (M, (?1)), the ?1 and the M are set such that the conversion percentage fn (M, (?1)) becomes a predetermined value Th or less.

Abstract: A piezoelectric vibrating piece includes a piezoelectric substrate and excitation electrodes. The piezoelectric substrate is formed in a flat plate shape and vibrates in a thickness-shear vibration mode. The excitation electrodes are disposed on respective both principal surfaces of the piezoelectric substrate. The excitation electrode includes a main thickness portion and an inclined portion. The main thickness portion has a constant thickness. The inclined portion is formed in a peripheral area of the main thickness portion. The inclined portion has a thickness that gradually decreases from a portion contacting the main thickness portion to an outermost periphery of the excitation electrode. An inclination width as a width of the inclined portion has a length that is equal to or more than 0.5 times and equal to or less than three times of a flexural wavelength. The flexural wavelength is a wavelength of a flexure vibration as an unnecessary vibration.

Abstract: A crystal resonator vibrates in a thickness-shear mode. The crystal resonator includes excitation electrodes being disposed on a front surface and a back surface of a crystal element. The excitation electrodes are disposed on the crystal element to have a positional relationship, where a displacement distribution at an edge of the excitation electrode on the front surface is identical to a displacement distribution at an edge of the excitation electrode on the back surface.

Abstract: A piezoelectric vibrating piece includes a vibrating piece body including a vibrator and at least one pair of excitation electrodes formed on a front surface and a back surface of the vibrator. The vibrating piece body is a twice rotated quartz-crystal vibrating piece. The pair of excitation electrodes are arranged in a Z??-axis direction determined by an X??-axis and obliquely disposed with respect to the Y?-axis direction. The X??-axis is rotated by 260° to 300° counterclockwise about a Y?-axis using a +X?-axis direction as a reference. The pair of excitation electrodes are formed to have respective semicircle shapes including straight line portions extending in the X??-axis direction and to be disposed in a state where the straight line portions overlapping with one another. The straight line portion of the excitation electrode includes an inclined portion that gradually decreases in thickness toward an end portion of the excitation electrode.

Abstract: An AT-cut crystal element includes a crystal element having two side surfaces (namely, a Z?-surface) intersecting with a Z-axis of a crystallographic axis thereof. At least one of the two side surfaces is constituted of three of first to third surfaces. The first to the third surfaces meeting following conditions: the first to the third surfaces intersect with one another in this order and formed by rotating a principal surface of the crystal element by predetermined angles; and expressing the angle of the first surface as ?1, a length of the first surface as D, a thickness of a part of the crystal element having the principal surface as t, and M=D/t, and a conversion percentage as fn (M, (?1)), the ?1 and the M are set such that the conversion percentage fn (M, (?1)) becomes a predetermined value Th or less.