US Patent No. 10,659,005

AT-CUT CRYSTAL ELEMENT, CRYSTAL RESONATOR AND CRYSTAL UNIT


Patent No. 10,659,005
Issue Date May 19, 2020
Title At-cut Crystal Element, Crystal Resonator And Crystal Unit
Inventorship Takayuki Kuwahara, Saitama (JP)
Kenji Shimao, Saitama (JP)
Hirokazu Iwata, Saitama (JP)
Assignee NIHON DEMPA KOGYO CO., LTD., Tokyo (JP)

Claim of US Patent No. 10,659,005

1. An AT-cut crystal element, comprising:side surfaces intersecting with a Z?-axis of a crystallographic axis of a crystal, and
at least one side surface of the side surfaces being constituted of three surfaces of a first surface, a second surface and a third surface,
wherein
the first surface, the second surface, and the third surface intersect in this order, and
the first surface is a surface corresponding to a surface where a principal surface is rotated around an X-axis of the crystal by 4°±3.5°, wherein the principal surface is an X-Z? surface of the AT-cut crystal element and the X-Z? surface is represented by the crystallographic axes of the crystal,
the second surface is a surface corresponding to a surface where the principal surface is rotated around the X-axis of the crystal by ?57°±5°, and
the third surface is a surface corresponding to a surface where the principal surface is rotated around the X-axis of the crystal by ?42°±5°.