JPS62234410A - Thickness-shear piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To deteriorate the Q value of the n-th higher harmonic vibration without deteriorating the vibration sharpness Q of the basic wave vibration, by forming an electrode thin film part at the center of an exciting electrode film formed on a piezoelectric element plate. CONSTITUTION:The electrode films 12 and 13 for excitation of piezoelectric element plate are formed in desired forms on both sides of a thickness-shear piezoelectric element plate 11. Then an electrode thin film part 14 is formed at the center of the film 12 within an area of <=1/2 the film 12. The energy enclosing distribution of a thickness-shear piezoelectric vibrator is concentrated at the center of the electrode film as the degree of higher harmonic vibrations is increased. Thus it is possible to change the balance of the frequency reduction value caused by the mass addition effect. Then the frequency difference can be increased between the basic wave vibration and the n-th higher harmonic vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an energy-trapped thickness-shear piezoelectric vibrator that excites fundamental wave vibration.

[Conventional technology]

Conventionally, this type of piezoelectric vibrator is shown in Fig. 4.
Excitation electrode films 2 and 3 were formed on the lower surface of the Lt capsule girder 1 using Il1 plates such as sieves.

[Problem that the invention seeks to solve]

The conventional piezoelectric vibrator described above has fundamental wave vibration, 3rd order, 5th order
When the next harmonic vibration is always available for excitation, l of the first harmonic vibration (n: third order, fifth order) of the piezoelectric vibrator is
When /n and the frequency of the fundamental wave principal image motion coincide, problems such as interference with each other and distortion in the output of the piezoelectric oscillator occur.

[Means for solving problems]

A piezoelectric vibrator that does not explode has a film thickness at the inner periphery that is smaller than the film thickness at the outer periphery in an area less than 1/2 of the excitation electrode film at the center of the excitation electrode film formed on the Horomisli piezoelectric element plate. 11r, it has a thin electrode film thin part.

[For production]

In the present invention, the thin electrode film portion deteriorates the uplift sharpness of the n-th harmonic transversal motion.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a thickness-shear piezoelectric vibrator according to the present invention, in which the button in the figure is a plan view and the button in the figure is a front sectional view. In the same figure, electrode films 12 and 13 for excitation of the piezoelectric element plate are formed in the required shapes on the upper and lower surfaces of the thickness-shear piezoelectric element plate 11, and in the center of the excitation electrode films 12 and 13 are formed. Electrode film thin part 1 in an area of 1/2 or less of the electrode film for use
4 is formed. In order to reduce the total thickness of the electrode film thin portion 14, the central part of the piezoelectric '1 base plate 11 is appropriately masked, the donut-shaped electrode film 12 is expanded, and then this electrode This can be easily obtained by forming the outer diameter of the polar film 15 that is approximately the same as the outer diameter of the film 12.

FIG. 2 is a diagram showing another embodiment of the present invention. In this figure, the difference from FIG. The outer edge masking portion is connected and fixed.

FIG. 3 is a diagram showing still another embodiment of the present invention,
In the same figure, electrode film thin portions 14 may be provided on the upper and lower surfaces of the pressure 'II blank plate 11.

It goes without saying that in the embodiment shown in FIG. tg1, the electrode film 15 may be formed first, and then the donut-shaped electrode film 12 may be formed.

〔Effect of the invention〕

As explained above, the present invention provides the following advantages: by forming a thin electrode film in the center of an excitation electrode film formed on a piezoelectric element plate,
The vibration sharpness (hereinafter referred to as Q) of the fundamental vibration (hereinafter referred to as Q) 1- can be degraded without deteriorating the Q ff & of the n-th harmonic vibration. In addition, in thickness-shear piezoelectric vibrators, energy is trapped or distributed in the center of the electrode film as harmonic vibrations occur, so the balance of frequency reduction due to the mass addition effect can be changed, and the fundamental wave vibration and Extremely excellent effects such as being able to expand the frequency difference with the n-th harmonic vibration can be obtained.

[Brief explanation of drawings]

FIG. 1(a), ←) is a plan view and a sectional view showing an embodiment of the exclusive Vec piezoelectric lifter according to the present invention, and FIGS. 2 and 3 are
FIG. 4 is a plan view and a sectional view showing a conventional example. 11-@·e piezoelectric element plate, 12...φ donut-shaped excitation electrode film, 13...excitation electrode film, 14...electrode film thin portion, 15...φ electrode film.

Claims (2)

[Claims] (1) In an energy-trapped thickness-shear piezoelectric vibrator that excites fundamental wave vibration in an excitation electrode film formed on a piezoelectric element plate, the excitation electrode film has an electrode whose inner circumference is thinner than its outer circumference. A thickness-shear piezoelectric vibrator characterized by having a thin membrane portion. (2) The thin part of the electrode film is formed in an area of 1/2 or less of the center of the excitation electrode film.
Thickness-slip piezoelectric vibrator as described in .