Abstract: In a quartz crystal unit, the unit comprising a quartz crystal tuning fork resonator having a quartz crystal tuning fork base, and first and second quartz crystal tuning fork arms, each of the first and second quartz crystal tuning fork arms having a length, and a first main surface and a second main surface opposite the first main surface, at least one groove being formed in a central linear portion of at least one of the first and second main surfaces of each of the first and second quartz crystal tuning fork arms and formed continuously in the central linear portion along the length of the corresponding one of the first and second quartz crystal tuning fork arms, an overall length of the quartz crystal tuning fork resonator being less than 2.1 mm.

Abstract: In a quartz crystal unit, the unit comprising a quartz crystal resonator having a base portion, and first and second vibrational arms connected to the base portion, at least one groove being formed in at least one of opposite main surfaces of each of the first and second vibrational arms, a length of the base portion being less than 0.5 mm and an overall length of the quartz crystal resonator being less than 2.1 mm, at least one mounting arm protruding from the base portion and being formed between the first and second vibrational arms, the at least one mounting arm extending in a common direction with the first and second vibrational arms.

Abstract: A quartz crystal unit comprising: a quartz crystal resonator having an overall length less than 2.1 mm and a base portion including a length L1 less than 0.5 mm, and first and second vibrational arms connected to the base portion, at least one groove being formed in a central linear portion of at least one of opposite main surfaces of each of the first and second vibrational arms so that a width of the at least one groove is less than a spaced-apart distance between the first and second vibrational arms, the at least one groove being formed continuously in the central linear portion along the length of the corresponding one of the first and second vibrational arms, the quartz crystal resonator being housed in a case, a lid being connected to the case to cover an open end of the case.

Abstract: A method for manufacturing a quartz crystal unit, comprising the steps of forming a quartz crystal tuning fork shape having a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines, a quartz crystal tuning fork resonator having the quartz crystal tuning fork shape, forming at least one groove in at least one of opposite main surfaces of each of the first and second quartz crystal tuning fork tines, determining each of a length of the at least one groove and an overall length of the quartz crystal tuning fork resonator so that a series resistance R1 of a fundamental mode of vibration of the quartz crystal tuning fork resonator is less than a series resistance R2 of a second overtone mode of vibration thereof, housing the quartz crystal tuning fork resonator in a case, connecting a lid to the case, and disposing a metal or a glass in a through-hole of the case.

Abstract: A quartz crystal unit comprising a quartz crystal tuning fork resonator having a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines, at least one groove being formed in at least one of opposite main surfaces of each of the first and second quartz crystal tuning fork tines, each of a length of the at least one groove and an overall length of the quartz crystal tuning fork resonator being determined so that a series resistance R1 of a fundamental mode of vibration of the quartz crystal tuning fork resonator is less than a series resistance R2 of a second overtone mode of vibration thereof, the quartz crystal tuning fork resonator being housed in a case, a lid being connected to the case to cover an open end of the case, a metal or a glass being disposed in a through-hole of the case.

Abstract: In a unit, the unit comprising a quartz crystal resonator having a base portion, and first and second vibrational arms, each of the first and second vibrational arms having a length and opposite main surfaces each including a central linear portion, at least one groove being formed in the central linear portion of at least one of the opposite main surfaces of each of the first and second vibrational arms so that the at least one groove is formed continuously in the central linear portion along the length of the corresponding one of the first and second vibrational arms, a length of the base portion being less than 0.5 mm and an overall length of the quartz crystal resonator being within a range of 1.02 mm to 1.95 mm.