Abstract: An AT-cut quartz-crystal vibrating piece includes a vibrator, a peripheral portion, and a level difference. The peripheral portion has a thickness thinner than a thickness of the vibrator. The level difference is on each of a front and a back of the quartz-crystal vibrating piece. The level difference is generated caused by a thickness difference between the vibrator and the peripheral portion. When a dimension along an X-axis of a crystal of the quartz-crystal vibrating piece is defined as Lx, a dimension along a Z?-axis of the crystal of the quartz-crystal vibrating piece is defined as Lz, a thickness of the vibrator is defined as t, and a height of the level difference is defined as d, Lx is in a range from 849 to 857 ?m, Lz is in a range from 625 to 645 ?m, and d/t is in a range of 0.094?d/t?0.11.

Abstract: A piezoelectric device includes 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. The first surface is a surface equivalent to a surface formed by rotating the principal surface by 4°±3.5° with an X-axis of the crystal as a rotation axis. The second surface is a surface equivalent to a surface formed by rotating the principal surface by ?57°±5° with the X-axis. The third surface is a surface equivalent to a surface formed by rotating the principal surface by ?42°±5° with the X-axis. When two corner portions on a side of a second side opposed to the first side of the AT-cut crystal element are viewed in plan view, each of the two corner portions have an approximately right angle.

Abstract: A piezoelectric device includes 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. The first surface is a surface equivalent to a surface formed by rotating the principal surface by 4°±3.5° with an X-axis of the crystal as a rotation axis. The second surface is a surface equivalent to a surface formed by rotating the principal surface by ?57°±5° with the X-axis. The third surface is a surface equivalent to a surface formed by rotating the principal surface by ?42°±5° with the X-axis. When two corner portions on a side of a second side opposed to the first side of the AT-cut crystal element are viewed in plan view, each of the two corner portions have an approximately right angle.

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 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 first depressed portion, the thick portion, a second depressed 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 first 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. The second depressed portion is a depressed portion disposed from the thick portion toward the second end portion side, depressed with a predetermined angle ?b and subsequently bulged, and connected to the second end portion.

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 first depressed portion, the thick portion, a second depressed 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 first 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. The second depressed portion is a depressed portion disposed from the thick portion toward the second end portion side, depressed with a predetermined angle ?b and subsequently bulged, and connected to the second end portion.

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.