Quartz crystal unit, quartz crystal oscillator and electronic apparatus

摘要

A quartz crystal unit has a quartz crystal tuning fork resonator having a thickness within a range of 0.05 mm to 0.18 mm, and at least one groove formed in at least one of opposite main surfaces of each of first and second tuning fork tines so that a length of the at least one groove is within a range of 20% to 78% of an overall length of the resonator and less than 1.29 mm. An electrode is disposed on at least one of a base portion and a surface of the at least one groove so that the electrode of the first tuning fork tine has an electrical polarity opposite to an electrical polarity of the electrode of the second tuning fork tine. The capacitance ratio r2 of a second overtone mode of vibration of the quartz crystal tuning fork resonator is greater than 1500. The quartz crystal tuning fork resonator is housed in a case having an open end, and a lid is connected to the case.

主权项

1. A quartz crystal unit comprising:
a case having an open end; a quartz crystal resonator; and a lid; wherein the quartz crystal resonator comprises a quartz crystal tuning fork resonator having a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the quartz crystal tuning fork base and the first and second quartz crystal tuning fork tines having a thickness within a range of 0.05 mm to 0.18 mm, each of the first and second quartz crystal tuning fork tines having opposite main surfaces and a first side surface and a second side surface opposite the first side surface in the width direction, the first side surface of the first quartz crystal tuning fork tine confronting the second side surface of the second quartz crystal tuning fork tine; wherein at least one groove having a base portion and a plurality of surfaces including a first surface opposite the first side surface is formed in at least one of the opposite main surfaces of each of the first and second quartz crystal tuning fork tines so that a length of the at least one groove formed in the at least one of the opposite main surfaces of each of the first and second quartz crystal tuning fork tines is within a range of 20% to 78% of an overall length of the quartz crystal tuning fork resonator and less than 1.29 mm, the quartz crystal tuning fork resonator having a capacitance ratio r1 of a fundamental mode of vibration and a capacitance ratio r2 of a second overtone mode of vibration; wherein an electrode is disposed on at least one of the base portion and the first surface of the at least one groove formed in the at least one of the opposite main surfaces of each of the first and second quartz crystal tuning fork tines so that the electrode disposed on the at least one of the base portion and the first surface of the at least one groove formed in the at least one of the opposite main surfaces of the first quartz crystal tuning fork tine has an electrical polarity opposite to an electrical polarity of the electrode disposed on the at least one of the base portion and the first surface of the at least one groove formed in the at least one of the opposite main surfaces of the second quartz crystal tuning fork tine and the capacitance ratio r2 of the second overtone mode of vibration of the quartz crystal tuning fork resonator is greater than 1500; wherein the quartz crystal tuning fork resonator is housed in the case; and wherein the lid is connected to the case to cover the open end of the case.