JPH06209225A - Piezoelectric vibrator for overtone oscillation - Google Patents

Abstract

(57) [Summary] [Object] To provide a highly reliable piezoelectric vibrator capable of more stable high frequency without deteriorating the CI value of the third overtone. A main part electrode 21a, which is a piezoelectric vibrator that vibrates overtones in a desired order and constitutes a main vibration energy confinement part that confines the main vibrations of the overtone vibrations in the desired order on one surface 11 of a piezoelectric substrate. An electrode absent portion 31 forming the vibration energy propagating portion and a sub-electrode 41a forming the vibration energy absorbing portion are formed,
In an overtone oscillation piezoelectric vibrator in which an electrode is formed on substantially the entire other surface of the piezoelectric substrate, a main electrode and a sub electrode are arranged in series in the X-axis direction of the piezoelectric substrate.
It was formed via the electrode absent portion. Further, the electrodes are formed in series in the piezoelectric substrate holding direction having a longitudinal direction and a lateral direction. The center of gravity of the piezoelectric substrate and the center of gravity of the main portion electrode are decentered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric resonator for overtone oscillation which enables oscillation at a desired overtone frequency without requiring an overtone resonance circuit.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 9 is a plan view of a conventional piezoelectric substrate, and FIG. 10 is a bottom view of FIG. The piezoelectric substrate 1 is made of an AT-cut crystal plate that causes thickness shear vibration, and a main electrode 2 is provided at the center of the front surface of the piezoelectric substrate 1 and an electrode 5 is provided at the center of the back surface of the piezoelectric substrate 1 to confine the main vibration energy. Is provided around it, and a vibration energy propagating portion (electrode absent portion) 3 having a cutoff frequency Fc higher than the cutoff frequency fc of the main vibration energy confining portion is provided around the cutout frequency Fc, and a cutoff frequency lower than the cutoff frequency Fc is further provided outside thereof. And a cutoff frequency Fc is provided.
Is lower than the desired sub-vibration frequency of the overtone vibration, and is the main vibration frequency f0 of this overtone vibration.
It is set higher, and the vibration energy absorbing section absorbs energy of vibration modes lower than the desired overtone order (including the fundamental wave vibration mode), and external vibrations higher than the main vibration to the outside. It was configured to leak.

[0003]

SUMMARY OF THE INVENTION For example, in a piezoelectric vibrator in which a third overtone is oscillated, the diameter of the main electrode is made smaller, the diameter of the piezoelectric substrate is made smaller, etc. in order to achieve higher frequency. However, if the size of the main electrode is too small, the CI value of the third overtone tends to deteriorate. Therefore, there is a method of reducing the diameter of the piezoelectric substrate without decreasing the diameter of the main electrode to increase the frequency. Further, along with the miniaturization of the holder, there are cases where the upper and lower parts in the direction orthogonal to the holding direction of the piezoelectric substrate are cut. However, when the above-mentioned matters are performed in the conventional electrode shape, there is a problem that desired electrical characteristics cannot be obtained because the size and shape of the peripheral electrode that is the vibration energy absorbing portion is restricted. Further, in the rectangular piezoelectric substrate, the peripheral electrode, which is the vibration energy absorbing portion, cannot be formed due to the size and shape of the piezoelectric substrate, which makes more stable overtone oscillation difficult.

An object of the present invention is to make the piezoelectric substrate more compact in response to higher frequencies and smaller retainers, and to make the piezoelectric substrate in a rectangular shape more stable without deteriorating the CI value of the third overtone. To provide a highly reliable piezoelectric vibrator capable of performing the above-mentioned overtone oscillation.

[0005]

Therefore, the present invention is a piezoelectric vibrator that vibrates overtones in a desired order, and mainly confines the main vibration of the overtone vibrations in the desired order on one surface of a piezoelectric substrate. A main electrode that constitutes the vibration energy confining portion, an electrode absent portion that constitutes the vibration energy propagating portion, and a sub electrode that constitutes the vibration energy absorbing portion are formed, and at least one of the other surfaces of the piezoelectric substrate is formed. In an overtone oscillation piezoelectric vibrator in which electrodes are formed on the opposing surfaces of the main electrode and the sub electrode, the main electrode and the sub electrode are absent in series in the X-axis direction of the piezoelectric substrate. Formed through the section. Further, the center of gravity of the piezoelectric substrate and the center of gravity of the main portion electrode are decentered.

Further, a piezoelectric vibrator which vibrates overtones in a desired order, and a main part electrode constituting a main vibration energy confining part for confining a main vibration of the overtone vibrations in the desired order on one surface of the piezoelectric substrate. An electrode absent portion forming the vibration energy propagation portion and a sub portion electrode forming the vibration energy absorbing portion are formed, and at least the main portion electrode and the sub portion electrode on the other surface of the piezoelectric substrate are opposed to each other. In an overtone oscillation piezoelectric vibrator having electrodes formed on its surface, a main electrode and a sub electrode are formed in series in the holding direction of the piezoelectric substrate via an electrode absent portion.
Further, the piezoelectric substrate shape is a piezoelectric substrate having a longitudinal direction and a lateral direction. Further, the center of gravity of the piezoelectric substrate and the center of gravity of the main portion electrode are decentered.

[0007]

When the main part electrode and the sub part electrode are formed in series in the X-axis direction of the piezoelectric substrate via the electrode absent part, it is desired to use, for example, the third overtone vibration as the main vibration. , The sub-electrode which constitutes the energy absorbing portion utilizes the difference in the vibration energy distribution of the fundamental wave extending in the X-axis direction of the piezoelectric substrate and the third-order overtone, and unnecessary sub-vibration (f1 , F2
Energy) can be suppressed to a level that is practically acceptable. Therefore, the size and shape of the sub electrode are not restricted, and only the piezoelectric substrate can be made small without making the main electrode small.

In addition, in the piezoelectric substrate having the above-mentioned piezoelectric substrate shape having a longitudinal direction and a lateral direction (for example, one obtained by cutting the upper and lower portions in a direction orthogonal to the holding direction of the piezoelectric substrate, or a rectangular piezoelectric substrate), When the main part electrode and the sub part electrode are formed in series in the holding direction of the piezoelectric substrate via the electrode absent part, for example, when it is desired to use the third overtone vibration as the main vibration, By utilizing the difference in the vibration energy distribution of the third-order overtone, no matter which direction of the piezoelectric substrate the X-axis is, there is a sub-electrode that constitutes the energy absorption part in the holding direction (longitudinal direction), and the fundamental wave vibration and the third-order vibration Unnecessary secondary vibration of overtone vibration (f
The energy of (1, f2, etc.) is suppressed to a level that does not hinder practical use, and since there is an edge portion of the piezoelectric substrate in the lateral direction, from the energy displacement distribution of the fundamental wave and the third-order overtone, the edge portion of the piezoelectric substrate is Since the loss of the fundamental wave vibration can be made larger than the loss of the third-order overtone, the fundamental wave vibration is suppressed and the third-order overtone vibration is facilitated. Therefore, the size and shape of the sub electrode are not restricted.

Also in the case of a disk-shaped piezoelectric substrate or a piezoelectric substrate in which the main electrode is provided in the vicinity of the outer periphery of the piezoelectric substrate, the main electrode and the sub electrode are connected in series in the holding direction of the piezoelectric substrate. , If it is desired to use the third order overtone vibration as the main vibration because it is formed via the electrode absent part, the difference in the vibration energy distribution of the fundamental wave and the third order overtone is used to determine which direction of the piezoelectric substrate Even if the X-axis is present, there is a sub-electrode that constitutes an energy absorption part in the holding direction (longitudinal direction), and the energy of sub-vibrations (f1, f2, etc.) that do not require fundamental wave vibration and third-order overtone vibration is practical. Since the main electrode is placed close to the outside of the piezoelectric substrate near the outer edge of the piezoelectric substrate, the energy displacement distribution between the fundamental wave and the third-order overtone causes the main electrode to be held at the edge of the piezoelectric substrate. Since it takes the loss of the fundamental wave vibration greater than the loss of tertiary overtones, by suppressing the fundamental wave vibration to facilitate tertiary overtone vibration. for that reason,
The size and shape of the sub electrode are no longer restricted.

By making the center of gravity of the piezoelectric substrate and the center of gravity of the main part electrode eccentric, the energy displacement distribution between the fundamental wave and the third-order overtone causes the loss of fundamental wave vibration at one end of the piezoelectric substrate to exceed the third-order overtone. Since it is larger than the loss of tone, it suppresses the fundamental vibration and facilitates the third overtone vibration.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. 1 is a plan view of a piezoelectric substrate showing a first embodiment of the present invention, and FIG. 2 is a bottom view of FIG. The piezoelectric substrate 11 is made of an AT-cut quartz plate that vibrates in a thickness shear vibration. The piezoelectric substrate 1 is formed with a size of 4φ, which is smaller than the conventional piezoelectric substrate 1 with a size of 6.5φ. is there. A main portion electrode 21a is provided on the surface of the piezoelectric substrate 11, an electrode absent portion 31 having a width G is provided in the piezoelectric substrate X axis direction, and a sub portion electrode 41a is provided outside thereof. Further, on the back surface of the piezoelectric substrate 11, an electrode 51 is formed on almost the entire surface of the piezoelectric substrate 11.
a is provided. In such a structure, the main part electrode 21a and a part of the back surface electrode 51a corresponding to the main part electrode 21a form a main vibration energy confinement part, and the electrode absent part 31 and a part of the back surface electrode 51a corresponding to it form a vibration energy propagation part. The sub-electrode 41a and a part of the back surface electrode 51a corresponding to the sub-electrode 41a form a vibration energy absorbing portion. In addition, from the main part electrode 21a to one end A of the piezoelectric substrate 11.
The lead electrode 21b is formed up to, and the sub-electrode 41a and the back surface electrode 51a are formed with the lead electrodes 41b and 51b up to the end B on the opposite side of the piezoelectric substrate 11. Then, these electrodes are formed by vacuum vapor deposition. In the first embodiment, the back surface electrode is almost the entire surface, but the same effect can be obtained if the back surface electrode is formed at least in the area where the main electrode and the sub electrode face each other.

Further, in the first embodiment of the present invention, the center of gravity 11P of the piezoelectric substrate 11 and the center of gravity 21P of the main portion electrode 21a are the same, but as a second embodiment, as shown in FIG. By forming the main electrode 22a and the sub electrode 42a in which the center of gravity 11P of the substrate and the center of gravity 22P of the main portion electrode are eccentric, the fundamental wave vibration is suppressed, and the effect of facilitating the third-order overtone vibration is obtained. is there. (In the second embodiment, the main electrode 22a and the sub-electrode 42a are formed in a quadrangular shape, but the same electrode shape as in the first embodiment may be used, of course. The fundamental wave suppression effect of is obtained.)

Next, a third embodiment of the present invention will be described with reference to FIG. The piezoelectric substrate 12 is an AT-cut crystal plate that vibrates in thickness shear, and is a piezoelectric substrate formed by cutting the upper and lower parts of the conventional piezoelectric substrate 1 as the holder becomes smaller. A main portion electrode 23a is provided on the surface of the piezoelectric substrate 12, an electrode absent portion 33 having a width G is provided in the piezoelectric substrate holding direction, and a sub portion electrode 43a is provided outside the electrode absent portion 33. In addition, the piezoelectric substrate 12
A back surface electrode is provided on almost the entire back surface of the piezoelectric substrate 12 (not shown). In such a structure, the main part electrode 23a and a part of the back surface electrode corresponding to the main part electrode 23a constitute a main vibration energy confining part, and the electrode absent part 33 and a part of the back surface electrode corresponding to the part a vibration energy propagating part. The partial electrode 43a and a part of the back surface electrode corresponding to the partial electrode 43a form a vibration energy absorbing portion. Then, these electrodes are formed by vacuum vapor deposition. In the third embodiment, the back surface electrode is almost the entire surface, but the same effect can be obtained if the back surface electrode is formed at least in the area where the main electrode and the sub electrode face each other.

Further, in the third embodiment of the present invention, the center of gravity 12P of the piezoelectric substrate 12 and the center of gravity 23P of the main portion electrode 23a are the same, but as a fourth embodiment, as shown in FIG. By forming the main part electrode 24a and the sub part electrode 44a in which the center of gravity 12P of the substrate and the center of gravity 24P of the main part electrode are eccentric, it is possible to suppress the fundamental wave vibration and facilitate the third-order overtone vibration. is there. (Also in the fourth embodiment, the main portion electrode 22a and the sub portion electrode 42 are also included.
Although the shape of a is formed in a quadrangular shape, an electrode shape similar to that of the third embodiment may of course be obtained, and a similar fundamental wave suppressing effect can be obtained. )

Next, a fifth embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a plan view of a piezoelectric substrate showing a fifth embodiment of the present invention, and FIG. 7 is a bottom view of FIG. The piezoelectric substrate 13 has a thickness shear vibration A
It consists of a T-cut rectangular crystal plate. A main portion electrode 25a is provided on the surface of the piezoelectric substrate 13, and an electrode absent portion 35 having a width G toward the piezoelectric substrate X axis (holding) direction.
Is provided, and a sub electrode 45a is provided outside the sub-electrode. On the back surface of the piezoelectric substrate 13, an electrode 55a is provided on almost the entire surface of the piezoelectric substrate 13. The back surface electrode 55a includes the front surface main electrode 25a and the electrode absent portion 3a.
5, it is formed on the entire surface so as to face the sub electrode 45a.
In such a structure, the main part electrode 25a and a part of the back surface electrode 55a corresponding to the main part electrode 25a form a main vibration energy confinement part, and the electrode absent part 35 and a part of the back surface electrode 55a corresponding to it form a vibration energy propagation part. The sub-electrode 45a and a part of the back surface electrode 55a corresponding to the sub-electrode 45a form a vibration energy absorbing portion. The lead electrode 25b is formed from the main part electrode 25a to one end C of the piezoelectric substrate 13, and the sub part electrode 45a and the back surface electrode 55a are the piezoelectric substrate 13.
Are connected at the end D on the opposite side of the. Then, these electrodes are formed by vacuum vapor deposition. For this reason, conventionally, in the rectangular piezoelectric substrate, the peripheral electrode, which is the vibration energy absorbing portion, could not be formed due to the size and shape, but the present invention enables more stable overtone oscillation. In the fifth embodiment, the back surface electrode is formed almost entirely, but the same effect can be obtained if the back surface electrode is formed at least in the area where the main electrode and the sub electrode face each other.

Further, in the fifth embodiment of the present invention, the center of gravity 13P of the piezoelectric substrate 13 and the center of gravity 25P of the main portion electrode 25a are the same, but as a sixth embodiment, as shown in FIG. By forming the main part electrode 26a and the sub part electrode 46a in which the center of gravity 13P of the substrate and the center of gravity 26P of the main part electrode are eccentric, the fundamental wave vibration is suppressed and the effect of facilitating the third-order overtone vibration is obtained. is there.

[0017]

According to the present invention, since the main electrode and the sub electrode are formed in series in the X-axis direction of the piezoelectric substrate via the electrode absent portion, for example, a third overtone vibration is generated. When you want to use it as the main vibration, X of the piezoelectric substrate
By utilizing the difference in the vibration energy distribution of the fundamental wave extending in the axial direction and the third-order overtone, the sub-electrodes that form the energy absorption part can generate unnecessary secondary vibration (f1, f2, etc.) of the fundamental wave and the third-order overtone vibration. Energy can be kept low enough for practical use. Therefore, the size and shape of the sub-part electrode are not restricted, the size and shape of the sub-part electrode which is the vibration energy absorbing part is reduced, and the piezoelectric substrate is made small without reducing the size of the main part electrode. It became possible to measure higher frequencies.

Further, the piezoelectric substrate has a piezoelectric substrate shape having a longitudinal direction and a lateral direction (for example, a piezoelectric substrate having upper and lower portions cut in a direction orthogonal to the holding direction of the piezoelectric substrate, or a rectangular piezoelectric substrate), Even in a disk-shaped piezoelectric substrate, if you want to use, for example, the third-order overtone vibration as the main vibration in the piezoelectric substrate in which the main electrode is provided close to the outer periphery of the piezoelectric substrate, the fundamental wave and the third-order overtone are generated due to the effect of the sub electrode. Using the difference in the vibration energy distribution, the energy of the fundamental vibration and the unwanted sub-vibrations (f1, f2, etc.) of the third-order overtone vibration are suppressed to a level that is practically unproblematic, and due to the effect of the edge part of the piezoelectric substrate, From the energy displacement distribution between the fundamental wave and the third-order overtone, the loss of the fundamental wave vibration at the edge of the piezoelectric substrate can be calculated from the loss of the third-order overtone. Hear take. Therefore, regardless of the direction of the X axis of the piezoelectric substrate, the fundamental vibration is suppressed,
The stabler third-order overtone vibration was facilitated, the size and shape of the sub-electrode were not restricted, and the deterioration of electrical characteristics was eliminated.

[Brief description of drawings]

FIG. 1 is a plan view of a piezoelectric substrate showing a first embodiment of the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a plan view of a piezoelectric substrate showing a second embodiment of the present invention.

FIG. 4 is a plan view of a piezoelectric substrate showing a third embodiment of the present invention.

FIG. 5 is a plan view of a piezoelectric substrate showing a fourth embodiment of the present invention.

FIG. 6 is a plan view of a piezoelectric substrate showing a fifth embodiment of the present invention.

FIG. 7 is a bottom view of FIG.

FIG. 8 is a plan view of a piezoelectric substrate showing a sixth embodiment of the present invention.

FIG. 9 is a plan view of a piezoelectric substrate showing a conventional example.

FIG. 10 is a bottom view of FIG.

[Explanation of symbols]

1, 11, 12, 13 ... Piezoelectric substrate 2, 21a, 22a, 23a, 24a, 25a, 26a
... Main part electrode 3,31,33,35 ... Electrode absent part 4 ... Peripheral part electrode 41a, 42a, 43a, 44a, 45a, 46a ...
・ Sub-electrodes 5, 51a, 55a ... Backside electrodes 21b, 25b, 41b, 45b, 51b, 55b ...
・ Lead electrode

Claims (4)

[Claims] 1. A piezoelectric vibrator which overtones in a desired order and which constitutes a main vibration energy confining part for confining a main vibration of the overtone vibration of the desired order on one surface of a piezoelectric substrate. An electrode absent portion forming the vibration energy propagation portion and a sub portion electrode forming the vibration energy absorbing portion are formed, and at least the main portion electrode and the sub portion electrode on the other surface of the piezoelectric substrate are opposed to each other. In an overtone oscillation piezoelectric vibrator having electrodes formed on its surface, a main electrode and a sub electrode are formed in series in the X-axis direction of the piezoelectric substrate via an electrode absent portion. A characteristic piezoelectric resonator for overtone oscillation. 2. A piezoelectric vibrator which overtones in a desired order and which constitutes a main vibration energy confining part for confining a main vibration of the overtone vibration of the desired order on one surface of a piezoelectric substrate. An electrode absent portion forming the vibration energy propagation portion and a sub portion electrode forming the vibration energy absorbing portion are formed, and at least the main portion electrode and the sub portion electrode on the other surface of the piezoelectric substrate are opposed to each other. In an overtone oscillation piezoelectric vibrator having electrodes formed on its surface, a main electrode and a sub electrode are formed in series in the holding direction of the piezoelectric substrate via an electrode absent portion. Piezoelectric vibrator for overtone oscillation. 3. The oscillator for overtone oscillation according to claim 2, wherein the shape of the piezoelectric substrate is a piezoelectric substrate having a longitudinal direction and a lateral direction. 4. The piezoelectric resonator for overtone oscillation according to claim 1, wherein the center of gravity of the piezoelectric substrate and the center of gravity of the main portion electrode are decentered.