JPS558172A - Tuning fork type piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To block the primary mode with the excitation of the secondary mode by providing the 1st and 2nd partial exciting electrodes on the tuning fork type piezoelectric plate and at the higher and the lower parts centering on the polarity inversion point between the positive and negative charge of the secondary mode resonance. CONSTITUTION:As for the flexuous oscillation of the tuning fork type piezoelectric plate, the polarity inversion point from the positive to negative charge exists within 0-0.4lt of full length lt of the leg part centering on the boundary point between the leg part and the basement in the case of the secondary mode excitation. Electrodes 4, 5, 10 and 11 plus 6, 7, 8 and 9 which are within range le1 from 0.2lt to the area near the upper end of leg part 1 and 2 are defined as the excitation electrodes of the 1st part; while electrodes 12, 13 and 17 plus 14, 15 and 16 within range l2e from 0.2lt of the leg part to 0.5lb in the lower direction of basement 3 are defined as the 2nd part excitation electrodes respectively. Then the electrodes the oblique line part and the dot line part in the figure are connected to terminal electrode 44 and 51 each to supply the power and then to secure the excitation in the secondary mode. Thus, both the same polarity charge generated at electrodes 4-7 plus 12, 13, 16 and 38 along with the different polarity charge generated at electrodes 8-11 plus 14, 15, 17 and 37 can be applied effectively, the charge of the primary mode being offset.