Patent ID: 6903618

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 fundamental mode of vibration, a second overtone mode of vibration, a quartz crystal tuning fork base, and a plurality of quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the quartz crystal tuning fork tines having a first main surface, a second main surface opposite the first main surface, and at least one groove having stepped portions formed in at least one of the first and second main surfaces; a case having an interior space for housing the quartz crystal tuning fork resonator and an open end communicating with the interior space; and a lid for covering the open end of the case; wherein a merit value M 2 for the second overtone mode of vibration of the quartz crystal tuning fork resonator is less than a merit value M 1 for the fundamental mode of vibration thereof, the merit values M 1 and M 2 being defined by the ratios Q 1 /r 1 and Q 2 /r 2 , respectively, where Q 1 and Q 2 represent a quality factor of the fundamental mode of vibration and the second overtone mode of vibration, respectively, of the quartz crystal tuning fork resonator and r 1 and r 2 represent a capacitance ratio of the fundamental mode of vibration and the second overtone mode of vibration, respectively, of the quartz crystal tuning fork resonator.