Patent ID: 7944131

Claim:
A quartz crystal unit comprising: a quartz crystal tuning fork resonator capable of vibrating in a flexural mode of an inverse phase and having a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines each connected to the quartz crystal tuning fork base, each of the first and second quartz crystal tuning fork tines having opposite main surfaces and opposite side surfaces; wherein at least one groove having a length is formed in at least one of the opposite main surfaces of each of the first and second quartz crystal tuning fork tines; wherein an electrode is disposed on a 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 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 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, the quartz crystal tuning fork resonator having an overall length; and wherein each of the 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 and the overall length of the quartz crystal tuning fork resonator is determined so that a series resistance R 1 of a fundamental mode of vibration of the quartz crystal tuning fork resonator is less than a series resistance R 2 of a second overtone mode of vibration thereof.