JPH0332075A - Piezoelectric element - Google Patents

Abstract

PURPOSE:To cause longitudinal and lateral slip deformations to take place simultaneously to achieve high mechanical strength by constructing from two constituent phases having different Curie points and different polarizability with respect to the polarizing electric field and causing the two constituent phases to have respective polarization directions orthogonal to each other. CONSTITUTION:A piezoelectric element is constructed from a constituent phase 1 having a high Curie point and consisting of composition with low polarizability with respect to the polarizing electric field, and a constituent phase 2 having a Curie point lower than that of the phase 1 and consisting of composition with higher polarizability with respect to the polarizing electric field. When d.c. voltage is applied to driving electrodes, elongation, lateral contraction, together with slip deformation take piece. At that time, in the phase 1, polarized in the direction perpendicular to the driving voltage, the longitudinal and the lateral deformations take place, and in the phase 2, polarized in the parallel direction, the slip deformation takes place. A compound mode deformation takes place due to the deformations of the phases 1, 2. Further, the deformation amounts of the longitudinal, lateral, and slip deformations can be changed by changing the mixing ratio of the phase 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric element that can be driven in a composite mode of vertical deformation, lateral deformation, and sliding deformation.

[Prior Art] Conventionally, when a voltage is applied to a piezoelectric element in a direction parallel to the polarization direction, the piezoelectric element undergoes vertical and lateral deformation, and when a voltage is applied to the piezoelectric element in a direction perpendicular to the polarization direction, the piezoelectric element undergoes a full deformation.

When the same piezoelectric element undergoes vertical deformation, horizontal deformation, or sliding deformation, it is necessary to form separate drive electrodes and drive them separately. Therefore, they cannot be driven at the same time. In order to cause vertical deformation, lateral deformation, and sliding deformation in a single element at the same time, it is necessary to prepare piezoelectric elements with different polarization directions separately, as shown in FIG. 6, and to integrate them by bonding or other methods.

[Problems to be Solved by the Invention] However, in a piezoelectric element in which a drive electrode for vertical deformation or lateral deformation and a drive electrode for sliding deformation are provided in the same element,
It is impossible to cause each deformation at the same time, and in a piezoelectric element in which two piezoelectric elements with different polarization directions are integrated by adhesive etc., a weak intermediate layer with an electrode between the two piezoelectric elements is used. exist, and there are major problems in terms of its practical strength.

The present invention has been made in order to solve the above-mentioned problems, and includes a piezoelectric element that is integrally sintered and consists of two constituent phases that have different polarizability with respect to the Curie point and a polarization electric field. The object of the present invention is to provide a piezoelectric element that simultaneously causes vertical deformation, lateral deformation, and sliding deformation by having a polarization direction orthogonal to the piezoelectric element, and has mechanical strength equivalent to that of a single element.

[Means for Solving the Problems] In order to achieve this object, the piezoelectric element of the present invention has two types of piezoelectric elements having different Curie points and polarization abilities with respect to polarization electric fields in arbitrary mixing ratios and arbitrary sizes. Each phase has a polarization direction perpendicular to the other. Further, opposing drive electrodes are formed on both end faces of the piezoelectric element.

[Function] In the present invention having the above configuration, the arbitrarily determined mixing ratio acts as a factor that controls the amount of deformation of vertical deformation, lateral deformation, and sliding deformation together with the two types of compositions constituting the piezoelectric element. In other words, it is a factor that determines the proportion of polarization in orthogonal polarization directions.

The arbitrarily determined size of each constituent phase, together with each sintering condition, acts as a factor that controls the diffusion reaction at the interface between the two constituent phases during integral sintering. In other words, it affects the mechanical strength of the integrally sintered piezoelectric element.

In addition, the difference in the Curie point of each constituent phase and the polarizability with respect to the polarization electric field is determined by the temperature between the two Curie points in the first and second polarization treatments that are performed to have orthogonal polarization directions. Moreover, it is carried out in a high electric field. During the first polarization process, the constituent phase with a lower Curie point assumes a cubic crystal structure and acts as an unpolarized phase. During the second polarization process, which is performed at a temperature lower than the Curie point of both constituent phases and in an electric field lower than the electric field during the first polarization process, the constituent phase with the lower Curie point is subjected to the first polarization process. The phase with a higher Curie point polarized in the first polarization direction is polarized in a direction perpendicular to the polarization direction of The direction of polarization is maintained. Therefore, the Curie point of the two constituent phases and the difference in polarizability with respect to the polarization electric field serve as factors that determine the polarization level in each orthogonal polarization direction. The driving electrode is formed as a counter electrode on an end face perpendicular to one polarization direction and parallel to the other orthogonal polarization direction, and serves as an electrode for simultaneously causing vertical deformation, lateral deformation, and sliding deformation.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

As shown in FIG. 1, the piezoelectric element of the present invention has a constituent phase 1 consisting of a composition with a high Curie point and a low polarizability with respect to a polarization electric field (a high electric field is required for polarization), and a constituent phase with a Curie point. 1 and has high polarizability with respect to the polarization electric field (
This is an integrally sintered composite piezoelectric ceramic element composed of a constituent phase 2 having a composition (polarization is completed in a low electric field).

As shown in FIG. 2, driving electrodes are formed facing both end faces perpendicular to the constituent phase 1 and parallel to the constituent phase 2. When a DC voltage is applied to this in the direction shown in FIG. 2, it stretches in the vertical direction, contracts in the horizontal direction, and undergoes sliding deformation. At this time, the component phase 1 polarized in the direction perpendicular to the driving voltage becomes a phase that causes vertical and horizontal deformation as shown in Figure 3, and the component phase 2 polarized in the parallel direction becomes a phase as shown in Figure 4. This is the phase that causes slip deformation. This deformation of the constituent phase 1.2 causes complex mode deformation as shown in FIG. 2.

Also, by changing the mixing ratio of constituent phases 1 and 2,
It is also possible to change the amount of vertical deformation, lateral deformation, and sliding deformation.

Next, if this element is driven with an AC voltage, the vertical vibration, lateral vibration, and shear vibration modes determined by the elastic modulus, density, and shape (thickness in the direction of the opposite electrode) of the piezoelectric element can be generated using the same counter electrode. It is also possible to be excited at each resonant frequency.

[Effects of the Invention] As is clear from the detailed description above, the present invention has the following effects:
A piezoelectric element is composed of a component phase polarized in a direction perpendicular to the drive electrode and a component phase polarized in a direction parallel to the drive electrode in one element, and is a composite element formed by integral sintering. Since it is a material, it has the advantage that vertical deformation, lateral deformation, and sliding deformation occur simultaneously, and it has the same mechanical strength as a single element.

[Brief explanation of drawings]

1 to 4 show examples embodying the present invention. FIG. 1 is a conceptual diagram of a piezoelectric element according to the present invention, and FIG. 2 is a diagram showing a piezoelectric element according to the present invention. FIG. 3 is a diagram showing the state of deformation when driven, FIG. 3 is a diagram showing the state of vertical deformation and horizontal deformation, and FIG. 4 is a diagram showing the state of sliding deformation. Further, FIG. 5 is a diagram of an example of an element configured to undergo vertical deformation, lateral deformation, and sliding deformation using the prior art. In the figure, 1 is a constituent phase, 2 is a constituent phase, and 3 is a driving electrode.

Claims (1)

[Claims] 1. It consists of two constituent phases with different Curie points and different polarizability for polarization electric fields, and because the two constituent phases have orthogonal polarization directions, they can be simultaneously driven by the same element and the same driving electrode. Vertical deformation, horizontal deformation,
A piezoelectric element configured to be driven in a complex mode of sliding deformation.