新しい音叉型水晶振動子 New Quartz Tuning Fork
In order to realize the electronic wristwatches with high accuracy and low power consumption, we developed the new quartz tuning fork which features the cubic frequency temperature characteristics in the vicinity of the room temperature. The important points are mentioned below, (1) M-cut ( M_1-, M_2-, M_3-, M_4-cuts) must be used. This angle of cut was predicted theoretically with the finite element method. (2) The flexural mode must be coupled with the torsional mode. When the fundamental vibration of the flexural mode is coupled with the fundamental vibration of the torsional mode, the change of resonance frequency is about 1 ppm in the temperature range from 0℃ to 7O℃. The frequency temperature characteristics of this resonator disperse due to the dispersion of the angle of cut and the dimensional dispersion resulting from the manufacturing processes. Therefore, we used the Ist overtone of the flexural mode instead of the fundamental vibration of that in order to compensate the dimensional dispersion which dominantly affects the frequency tempetature characteristics, and established the adjustment method of the frequency temperature characteristics.
日本時計学会誌 (96), 25-54, 1981-03-25