Piezoelectric quartz vibrator with heating electrode means

Claim 1

A piezoelectric quartz vibrator which commprises an orbicular quartz plate cut in parallel to XZ'-plane of a quartz crystal, excitation electrode means of a substantially round form provided on and along the central areas of the major faces of the quartz plate, and heating electrode means to maintain the quartz plate at a desired temperature, a said heating electrode means being in a form of a circular arc provided on and along said major face and concentrically to and apart from said excitation electrode means, and a said heating electrode means extending exclusively within an angular range of ±80° as measured from the Z'-axis including the center of said excitation electrode means of the quartz crystal, where a counterclockwise direction in the first quadrant or a clockwise direction in the second quadrant is indicated at the positive sign, and a counterclockwise direction in the third quadrant and a clockwise direction in the fourth quadrant is indicated at the negative sign, in which quadrants are taken said center of said excitation electrode means for the origin, said Z'-axis for the abscissa and the X-axis of the quartz crystal for the ordinate; whereby change in the resonant frequency of the quartz plate due to the inner strain thereof caused by the heating the quartz plate by means of said heating electrode means is minimized.