| 摘要 |
PURPOSE:To enable mass-production of long and rectangular AT cut oscillators, by selecting the length of X, Z' axes of the crystall oscillator of rectangular AT cut. CONSTITUTION:The size of the crystal chip 2 of rectangular AT cut is l toward X axis, W toward Z' axis, and t in thickness. The both ends 3 lengthwise l are of bevel shape, the coupling between the parasitic oscillation and the major oscillation is weakened, and the lowering in the resonance sharpness is avoided. It can be one side bevel or the convex type of lens shape. For mass-production, simple rectangular shape can be made. Further, by selecting W/t as 3.1 to 3.7, and l/t as 14.5 to 16.2, the frequency versus temperature coefficient to be satisfied in mass-productive machining accuracy can be obtained and the tolerance of the width is realistic. Further, with a slope of XY' plane about 5 deg. for the X axis this side, W/t can be smaller, and the increase in the temperature at curved point of the frequency temperature performance from the AT cut oscillator of an infinite plate due to piezoelectric anisotropy can be avoided. Thus, the oscillators possible for mass-production in machining accuracy, small in size and excellent, can be established. |
