JPH1151959A - Piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator in which the resonance damping time in the direction of deflection of the vibrator is shortened. SOLUTION: In a first vibrator 21 of a cantilever structure in which one end of a first plate-shaped vibrator 21a is fixed to a first support base 21b and a first weight 21c is fitted to the other end of the first vibrator 21c, and a second vibrator 22 of a cantilever structure in which one end of a second plate-shaped vibrator 22a is fixed to a second support base 22b and a second weight 22c is fitted to the other end of the second vibrator 22a; the first support base 21b and the second support base 22b are fixed to each other in the state that the surface of the first vibrator 21a and that of the second vibrator 22a have been brought into parallel to each other, and a cushioning material 23 is provided between the first weight 21c and the second weight 22c. Since the resonance in the direction of deflection of two vibrators is quickly damped, in the signal being output from a piezoelectric element that has been stuck on the vibrator, the signal attributable to the resonance in the direction of deflection of the vibrator can be reduced, and an accurate output in accordance with the actual acceleration can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric vibrator, and more particularly to a piezoelectric vibrator used for a piezoelectric acceleration sensor used in an automobile navigation system.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional piezoelectric vibrator. FIG.
Is an example of a piezoelectric vibrator having a cantilever structure.

In FIG. 5, a piezoelectric vibrator 1 includes a plate-shaped vibrator 2, piezoelectric elements 3a and 3b attached to one main surface of the vibrator 2, and a piezoelectric element 3c attached to the other main surface. And 3d, horizontal support parts 4a and 4b, weight attachment part 5, connecting parts 6, 7, 8, 9, weight 10, and support base 11. The coupling parts 6, 7, 8, 9 are respectively composed of two couplers 6a and 6b, 7a and 7b, 8a and 8
b, 9a and 9b. The horizontal supports 4a and 4b are provided with four couplers 6a, 6b and 7a extending in a direction parallel to the surface of the vibrating body 2 and perpendicular to the longitudinal direction thereof.
The vibrating body 2 is connected to one end in the longitudinal direction of the vibrating body 2 by two connecting portions 6 and 7 composed of the vibrating body 2 and the connecting portion 7b. The weight mounting portion 5 also includes four couplers 8a, 8b, and 9a extending in a direction parallel to the plane of the vibrating body 2 and perpendicular to the longitudinal direction.
The vibrating body 2 is connected to the other end of the vibrating body 2 in the longitudinal direction by two connecting portions 8 and 9 formed of the vibrating body 9 and the connecting portion 9b. The weight 10 is attached to the weight attachment section 5.

Here, the vibrating body 2, the horizontal support portions 4a and 4b, the weight attaching portion 5, the connecting portions 6, 7, 8 and 9
Are integrally formed by punching a constant elastic metal material such as an elinvar into a predetermined shape. In addition, couplers 6a, 6b, 7 that constitute the connecting portions 6, 7, 8, and 9
Each of a, 7b, 8a, 8b, 9a and 9b is formed of a thin member so as not to hinder the stretching vibration of the vibrating body 2 in the longitudinal direction. Then, the horizontal support portions 4a and 4b are fixed to the support base 11, and as a result, the vibrating body 2 has a cantilever structure in which the vibrating body 2 is held by the connecting portions 6 and 7 at one end in the longitudinal direction.

In the piezoelectric vibrator 1 thus configured, the piezoelectric elements 3a and 3c provided on the other end in the longitudinal direction of the vibrator 2 and the piezoelectric elements 3b and 3d provided on one end are Electrodes are formed on both sides and drive signals are applied. The piezoelectric element has the property of contracting or expanding as a whole depending on the direction of the voltage applied to the electrodes on both surfaces. Therefore, in the piezoelectric vibrator 1, if the two piezoelectric elements 3b and 3d on one end side of the vibrating body 2 contract due to the drive signal, the two piezoelectric elements 3a and 3c on the other end side expand, and the two piezoelectric elements on one end side expand. When the piezoelectric elements 3b and 3d expand, the two piezoelectric elements 3a and 3c at the other end contract. As a result, the vibrating body 2 performs a stretching vibration in which one end and the other end alternately contract and expand alternately in response to the drive signal. At this time, a signal corresponding to the expansion and contraction vibration of the piezoelectric element is output from the electrode formed on each piezoelectric element. In this case, since the one end side and the other end side of the vibrating body 2 perform stretching vibrations in opposite directions, the entire length of the vibrating body 2 does not change during the stretching vibration.

When acceleration is applied to the piezoelectric vibrator 1 in a direction perpendicular to the plane of the vibrating body 2 in the state where the vibrating body 2 is performing stretching vibration, the horizontal supporting portions 4a and 4 Deflection occurs from the portion held by 4b and the connecting portions 6 and 7. At this time, the weight 10 functions to increase the deflection of the vibrating body 2. When the vibrating body 2 bends, the piezoelectric elements 3a, 3b, 3c, and 3d also bend. When the piezoelectric elements 3a, 3b, 3c, and 3d bend and expand and contract by a drive signal, the piezoelectric elements 3a, 3b
From the electrodes provided at b, 3c, and 3d, signals corresponding to the stretching vibration are output after being deformed by bending. The acceleration applied to the piezoelectric vibrator 1 can be detected by measuring these signals and comparing them with the drive signals.

[0007]

As described above, the vibrating body 2 of the piezoelectric vibrator 1 bends together with the piezoelectric elements 3a, 3b, 3c and 3d with respect to the acceleration in the direction perpendicular to the surface thereof.
The signals output from the piezoelectric elements 3a, 3b, 3c, 3d are changed according to the acceleration.

In the case where the acceleration suddenly disappears after the acceleration is once applied, the vibrating body 2 has one end as a fixed end (node) and the other end as an open end (antinode). Resonance vibration in the direction (deflection direction) perpendicular to the surface of
It gradually attenuates and stops over time. FIG. 6 shows how the amplitude of the resonance in the bending direction attenuates with time. In the case of using a soft material for the vibrating body, the resonance frequency of the vibrating body becomes low, and the time until it attenuates becomes long, especially in order to increase the deflection of the vibrating body and increase the sensitivity of acceleration detection. Become. In this case, the signal output from the piezoelectric element includes a signal corresponding to the actual acceleration and a signal caused by the deflection of the vibrating body 2 due to the resonance until the resonance in the bending direction of the vibrating body 2 is attenuated. Since they are superimposed, there is a problem that an accurate signal corresponding to the actual acceleration cannot be obtained.

Accordingly, the present invention provides a piezoelectric vibrator in which the decay time of resonance in the bending direction of the vibrating body is reduced.

[0010]

In order to solve the above problems, a piezoelectric vibrator according to the present invention has a piezoelectric element attached to both sides of a plate-shaped first vibrating body, and the first vibrating body is provided with a piezoelectric element. A first vibrator having a cantilever structure in which one end is fixed to a first support base and a first weight is attached to the other end of the first vibrating body, and one end of a plate-shaped second vibrating body Is fixed to a second support, and a second vibrator having a cantilever structure in which a second weight is attached to the other end of the second vibrator, the first vibrator and the second vibrator The first support and the second support are fixed to each other such that the surfaces of the vibrators are parallel to each other, and a cushioning material is provided between the first weight and the second weight. It is characterized by having.

Further, the piezoelectric vibrator of the present invention has a plate-shaped first vibrator.
A piezoelectric element attached to both surfaces of the vibrating body, one end of the first vibrating body fixed to a first support, and a first weight attached to the other end of the first vibrating body. A cantilever structure in which a first vibrator having a structure and one end of a plate-shaped second vibrator are fixed to a second support table, and a second weight is attached to the other end of the second vibrator. The first support and the second support are fixed to each other such that the surfaces of the first and second vibrators are parallel to each other. The first weight and the second weight are arranged in contact with each other, and at least portions of the first and second weights that contact each other are made of a cushioning material.

With this configuration, the piezoelectric vibrator of the present invention can reduce the decay time of resonance in the bending direction of the vibrator.

[0013]

FIG. 1 shows an embodiment of the piezoelectric vibrator of the present invention. In FIG. 1, the piezoelectric vibrator 20 includes a first vibrator 21, a second vibrator 22, and a buffer 23. Note that the configuration of each of the first vibrator 21 and the second vibrator 22 in FIG. 1 is simplified, and the detailed configuration is basically the same as the conventional piezoelectric vibrator shown in FIG. Yes, and each works the same. However,
No piezoelectric element is attached to the second vibrator 22, and the second vibrating body 22a does not perform stretching vibration.

The first vibrator 21 mainly includes a first vibrator 21a, a first support 21b, and a first weight 21c, and serves as a node of resonance of the first vibrator 21a in the bending direction. One end is fixed to the first support base 21b, and a first weight 21c is attached to the other end that also forms the antinode of resonance. Similarly, the second vibrator 22 mainly includes a second vibrator 22a, a second support base 22b, and a second weight 22c, and serves as a node of resonance in the bending direction of the second vibrator 22a. One end is fixed to the second support base 22b, and a second weight 22c is attached to the other end that forms an antinode of resonance. Then, the first vibrating body 21a and the second vibrating body 22a
So that the surfaces of the first support table 21 are parallel to each other.
b and the second support 22b are fixed to each other, and a cushioning material 23 made of silicon rubber is sandwiched between the first weight 21c and the second weight 22c. Also, the first vibrating body 21a
The resonance frequencies of the second vibrating body 22a in the bending direction are set to be different from each other. The cushioning member 23 is provided by being adhesively fixed to at least one of the weights so as not to come off between the first weight 21c and the second weight 22c.

In the piezoelectric vibrator 20 configured as described above, the first vibrating body 21a and the second vibrating body 22a are performing the expansion and contraction vibration by the drive signal in the direction perpendicular to the plane of the vibration body. When acceleration is applied, both the first vibrating body 21a and the second vibrating body 22a
1b and one end fixed to the second support 22b as a fulcrum. Then, when the acceleration stops, the deflection tends to return to its original state, and resonance in the bending direction occurs. At this time,
The first weight 21c and the second weight 22c are joined via a buffer 23, and the first vibrating body 21a and the second
Since the resonance frequencies of the vibrating members 22a are set to be different, the first vibrating member 21a and the second vibrating member 2a
In any of 2a, resonance in the bending direction cannot be freely performed, and both resonance frequencies converge to an intermediate frequency between the two. Moreover, the cushioning member 23 absorbs the resonance energy of the first vibrating body 21a and the second vibrating body 22a in the bending direction. As a result, the first vibrating body 21a and the second vibrating body 22
The amplitude of the resonance in the bending direction of a attenuates more rapidly than the resonance alone.

FIG. 2 shows how the amplitude of resonance in the bending direction of the two vibrators of the piezoelectric vibrator 20 attenuates with time. As described above, the amplitude is attenuated in a short time as compared with the resonance in the conventional example shown in FIG. FIG. 3 shows a state in which the resonance vibration in the bending direction of the first vibrating body 21a and the second vibrating body 22a changes immediately after the resonance starts. In FIG. 3, a is the first vibrating body 21a,
"b" indicates a temporal change in the amplitude of resonance in the bending direction of the second vibrating body 22a. As shown in FIG. 3, two vibrators 21a and 22a having different resonance frequencies, that is, different resonance periods are integrated, so that the two vibrators 21a
22a and 22a cannot freely oscillate with each other, and converge to a certain period of vibration.

As described above, since the resonance in the bending direction of the first vibrating body 21a and the second vibrating body 22a is rapidly attenuated, the signal output from the piezoelectric element attached to the two vibrating bodies is reduced. Thus, the number of signals caused by resonance in the bending direction of the vibrating body is reduced, and an accurate output corresponding to the actual acceleration can be obtained.

In the piezoelectric vibrator 20, the cushioning material 23 made of silicon rubber is used. However, the material of the cushioning material is limited to silicon rubber as long as it absorbs resonance energy and has a function as a cushioning material. is not.

In FIG. 1, the first weight 21c
The cushioning member 23 is provided between the second weight 22c and the second weight 22c.
As shown in the piezoelectric vibrator 30 of FIG.
The first weight 31a and the second weight 32a attached to the other ends of the first weight 31a and the second vibrating body 22a are made of a material such as silicon rubber, and the first weight 3a is used without using a separate cushioning material.
The first weight 32a and the second weight 32a themselves may have a function as a cushioning material, and may be arranged in contact with each other. In FIG. 4, the same or equivalent parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. Even in such a configuration, the resonance in the bending direction of the two vibrators is attenuated more rapidly than the resonance of the single vibrator, and the signal output from the piezoelectric element attached to the vibrator is not vibrated by the resonance. Signals due to body deflection are reduced, and an accurate output corresponding to the actual acceleration can be obtained. In the piezoelectric vibrator 30, the entire first weight 31c and the second weight 32c are made of a material which also functions as a cushioning material such as silicon rubber. However, the first weight 31c and the second weight 32c are limited to a portion where the two weights are in contact with each other. The same operation and effect can be obtained even if the material is partially changed to a material such as silicon rubber having a function as a cushioning material.

In each of the above-described embodiments, the piezoelectric element is attached only to the first vibrator of the first vibrator for acceleration detection. However, the second vibrator of the second vibrator may be used if necessary. A piezoelectric element may be attached to the second vibrating body so as to also serve as acceleration detection.

[0021]

According to the piezoelectric vibrator of the present invention, two vibrators having a cantilever structure are fixed to one end of the vibrating body with the surfaces of the two vibrating bodies parallel. Are fixed to each other, and two weights provided at the other end of the vibrating body are arranged with a cushioning material interposed therebetween. As a result, the resonance in the bending direction of the two vibrators is rapidly attenuated, so that the number of signals output from the piezoelectric element attached to the vibrator due to the resonance in the bending direction of the vibrator is reduced. Thus, an accurate output corresponding to the actual acceleration can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a piezoelectric vibrator of the present invention.

FIG. 2 is a diagram showing a change over time of the amplitude of resonance in the bending direction of a vibrating body of the piezoelectric vibrator of FIG. 1;

FIG. 3 is a diagram showing a time change of resonance in a bending direction of two vibrators of the vibrator of FIG. 1;

FIG. 4 is a perspective view showing another embodiment of the piezoelectric vibrator of the present invention.

FIG. 5 is a perspective view showing an example of a conventional piezoelectric vibrator.

6 is a diagram showing a time change of the amplitude of resonance of the piezoelectric vibrator in FIG. 5 in the bending direction of the vibrating body.

[Explanation of symbols]

 Reference Signs List 20 piezoelectric oscillator 21 first oscillator 22 second oscillator 21a first oscillator 22a second oscillator 21b first support 22b second support 21c second 1st weight 22c ... second weight 23 ... cushioning material

Claims (2)

[Claims] 1. A piezoelectric element is attached to both sides of a plate-shaped first vibrating body, one end of the first vibrating body is fixed to a first support, and the other end of the first vibrating body is attached to the first vibrating body. A first vibrator having a cantilever structure to which a first weight is attached, and one end of a plate-shaped second vibrator fixed to a second support table, and a second vibrator connected to the other end of the second vibrator. A second vibrator having a cantilever structure to which two weights are attached, wherein the first vibrating body and the second vibrating body are parallel to each other, A piezoelectric vibrator, wherein the second support bases are fixed to each other, and a cushioning material is provided between the first weight and the second weight. 2. A piezoelectric element is attached to both sides of a plate-shaped first vibrating body, one end of the first vibrating body is fixed to a first support, and the other end of the first vibrating body is A first vibrator having a cantilever structure to which a first weight is attached, and one end of a plate-shaped second vibrator fixed to a second support table, and a second vibrator connected to the other end of the second vibrator. A second vibrator having a cantilever structure to which two weights are attached, wherein the first vibrating body and the second vibrating body are parallel to each other, The second support is fixed to each other, the first weight and the second weight are arranged in contact with each other, and at least a portion of the first and second weights in contact with each other is made of a cushioning material. A piezoelectric vibrator characterized by the following.