Patent ID: 8427035

Claim:
A vibration device comprising: a vibrating reed including a base having a notch between one end and the other end, a plurality of vibrating arms extending from the one end of the base, and each including an arm section, a weight section located on an opposite side of the arm section to the base side and having a width larger than a width of the arm section, and a groove section provided to at least one of both principal surfaces of the arm section along a longitudinal direction of the arm section, and a support section connected to the other end of the base, wherein a mechanical resonant frequency f of the vibrating reed is higher than a thermal relaxation frequency f 0 of the vibrating reed, and assuming that a closest approach distance between an outer edge of the notch and an outer edge of a crotch section formed between the vibrating arms is a base flexion width Wb, and an arm width of the vibrating arm in a case of replacing a cross-sectional shape of the vibrating arm in a plane perpendicular to the longitudinal direction of the vibrating arm with a rectangular shape having a thermoelastic loss equivalent to a thermoelastic loss of the cross-sectional shape and a thickness equal to a thickness of the cross-sectional shape is an effective arm width We, a relationship of Wb>We is satisfied.