Patent ID: 8907548

Claim:
A resonator element comprising: a base portion provided on a plane including a first axis and a second axis orthogonal to the first axis; a vibrating arm extending from the base portion in the first axis direction, the vibrating arm including a terminal end disposed opposite the base portion; an excitation electrode provided on the vibrating arm so as to excite the vibrating arm; and a first mass portion provided on the vibrating arm so as to adjust the frequency of the vibrating arm, the first mass portion being provided at a location spaced apart from the terminal end of the vibrating arm in the first axis direction, wherein the vibrating arm performs flexural vibration in a direction perpendicular to the plane and has a first surface which contracts or expands with the flexural vibration and a second surface which expands when the first surface contracts and contracts when the first surface expands, wherein the first mass portion is provided on the first surface, and wherein the location of the excitation electrode is provided only in a region of the vibrating arm located at a distance less than or equal to ½ of an entire length of the vibration arm in the first axis direction from an end of the vibrating arm proximate the base portion, and the location of the first mass portion is provided in a region of the vibrating arm located at a distance greater than ½ of the entire length of the vibration arm in the first axis direction from the end of the vibrating arm proximate the base portion, and is formed from a material having a density D (in units of 10 3 kg/m 3 ) that is in the range of 2.20≦D≦8.92.