Piezoelectric blank, piezoelectric vibration element and piezoelectric vibration device

Abstract

A crystal blank includes a vibrating arm which extends in a direction intersecting the polarization direction. In at least one of the upper surface and lower surface which are parallel to the direction of extension of the vibrating arm and run along polarization direction, the vibrating arm is provided with two recesses (grooves) in the width direction of the surface thereby having a pair of outer walls which are positioned on the two sides of the two recesses and a middle wall which is positioned between the two recesses. In the middle wall, the apex part is located at a position lower than the apex part of each of the pair of outer walls and is thinner than each of the pair of outer walls at the same heights.

Dependencies are inferred from the claim text.