Patent ID: 8217736
Filing Date: 2012-07-10
Classification: H03H,H04R,Y10T

Abstract:
1. A quartz crystal unit comprising: a quartz crystal resonator; a case having a mounting portion; and a lid; wherein the quartz crystal resonator comprises a quartz crystal tuning fork resonator having a quartz crystal tuning fork shape including 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 first and second quartz crystal tuning fork tines having opposite main surfaces and opposite side surfaces; wherein at least one groove having at least three surfaces including a first surface opposite at least one of the opposite side surfaces and a second surface connected to the first surface through a third surface 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 at least one of the first and second surfaces 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 on the at least one of the opposite side 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 opposite side surfaces of the first quartz crystal tuning fork tine has the same electrical polarity as an electrical polarity of the electrode disposed on the at least one of the first and second surfaces 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 electrode disposed on the at least one of the first and second surfaces 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 the electrical polarity of the electrode disposed on the at least one of the first and second surfaces 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 vibrating in a flexural mode of an inverse phase; wherein the quartz crystal tuning fork resonator has a quality factor Q wherein the dimension of each of the quartz crystal tuning fork shape, 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 electrode disposed on the at least one of the first and second surfaces 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 determined so that the merit value M wherein the quartz crystal tuning fork resonator is mounted on the mounting portion of the case; and wherein the lid is connected to the case.