Patent ID: RE44423

Claim:
A method for manufacturing a quartz crystal unit, comprising the steps of: forming at least one quartz crystal tuning fork resonator by etching a quartz crystal wafer to form a quartz crystal tuning fork base, a plurality of quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, and at least one groove having a plurality of stepped portions in at least one of opposite main surfaces of each of two of the quartz crystal tuning fork tines , and disposing a first electrode on at least one of the stepped portions of at least one of the grooves and a second electrode on at least one side surface of each so that a width of the at least one groove formed in the at least one of the main surfaces of each of the two of the quartz crystal tuning fork tines is greater than a distance in the width direction of the at least one groove measured from an outer edge of the at least one groove to an outer edge of the corresponding one of the two of the quartz crystal tuning fork tines; adjusting at least twice and in different steps a frequency of oscillation of the quartz crystal tuning fork resonator; disposing an electrode on a surface of the at least one groove formed in the at least one of the main surfaces of one of the two of the quartz crystal tuning fork tines and disposing an electrode on a surface of the at least one groove formed in the at least one of the main surfaces of the other of the two of the 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 main surfaces of the one of the two quartz crystal tuning fork tines 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 main surfaces of the other of the two quartz crystal tuning fork tines; providing a case having an interior space and an open end communicating with the interior space a mounting portion ; providing a lid for covering the open end of the case; after the disposing step, mounting the quartz crystal tuning fork resonator in the interior space on the mounting portion of the case; and connecting the lid to the case to cover the open end thereof after the mounting step, adjusting at least once a frequency of oscillation of the quartz crystal tuning fork resonator .