JPH044765A - Laminated piezoelectric actuator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminated piezoelectric actuator.

[Prior Art] As a conventional example of a laminated piezoelectric actuator, a structure as shown in FIG. 5, for example, has been proposed. In this stacked piezoelectric actuator, a plurality of piezoelectric elements 101 are bonded and stacked, and a variable voltage circuit 110 alternately applies positive and negative voltages to the bonded portion to vibrate.

[Problems to be Solved by the Invention] However, in such conventional laminated piezoelectric actuators, each piezoelectric element is entirely bonded, so the lateral displacement of the piezoelectric element is suppressed, and only the vertical displacement is utilized. Not yet. In order to obtain a larger displacement, it is necessary to increase the applied voltage or increase the number of laminated piezoelectric elements; the former method has the risk of destroying the element;
The latter method had the problem of high cost.

The present invention has been made to solve the above-mentioned problems, and provides a multilayer piezoelectric actuator that can obtain a larger displacement than conventional ones without changing the magnitude of applied voltage or the number of laminated piezoelectric elements. is intended to provide.

[Means for Solving the Problems] In order to achieve this object, the laminated piezoelectric actuator of the present invention has the following features. A plurality of piezoelectric elements each having a convex portion formed on one side and a concave portion formed on the other side are bonded together by bonding the convex portions to each other with a rigid material in between, and further bonding the concave portions to each other to form a piezoelectric element group. A group of piezoelectric elements is surrounded by a conductive elastic member having conductivity and elasticity, and voltages of different polarities are applied to the protrusion side and the recess side through the conductive elastic member to vibrate.

[Operation] In the laminated piezoelectric actuator of the present invention having the above configuration, by applying voltages of different polarities to the convex side and the concave side of the piezoelectric element group through the conductive elastic member,
Bending displacement and thickness direction displacement occur in each piezoelectric element, causing it to vibrate.

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

First, the structure of the laminated piezoelectric actuator of this embodiment will be explained using FIG.

The laminated piezoelectric actuator of this embodiment has a plurality of piezoelectric elements 1 bonded and laminated, and the piezoelectric elements 1 are surrounded by conductive rubbers 8 and 9 that are insulated from each other.

The piezoelectric element 1 has thin film electrode surfaces formed on both sides, and as shown in FIG. 2, a positive electrode adhesive part 4 and a negative electrode adhesive part 5 are provided on the upper surface 2 and lower surface 3, respectively. Furthermore, the piezoelectric element 1 is polarized in the direction indicated by the arrow. Piezoelectric element 1
The positive electrode adhesive part 4 is made of a rigid material 11 that is not electrically displaced.
It is bonded to the positive electrode bonding part 4 of another piezoelectric element 1 with
Further, the negative electrode bonding portion 5 is bonded to the negative electrode bonding portion 5 of another piezoelectric element 1. The upper surface 2 and lower surface 3 of the piezoelectric element 1 are connected to an external positive electrode 6 and an external negative electrode 7 within the conductive rubber 8 and 9.
are glued and fixed, respectively. Also, the external positive electrode 6
and external negative electrode 7 are connected to variable voltage circuit 10.

Next, the effect will be explained.

When the variable voltage circuit 10 generates a voltage of Vx [v],
+Vx [v] to the external positive electrode 6, O[v] to the external negative electrode 7
A voltage of [v] is applied. Then, voltages of +Vx [V] and O [v] are applied to the upper surface 2 and lower surface 3 of all the stacked piezoelectric elements 1 via the external positive electrode 6 and the external negative electrode 7, respectively. As a result, a force that extends in the thickness direction and a force that shrinks in the length direction act on the piezoelectric element 1, and since the rigid substance 11 is bonded to the upper surface 2, the shrinking force is suppressed, and as shown in FIG. Bending displacement occurs (the dotted line in the figure shows the state before displacement, and the solid line shows the state after displacement.) This amount of bending displacement is several times larger than the amount of induced strain in the thickness direction.

Assuming that the sum of the induced strain amount and the bending displacement amount per piezoelectric element 1 is ΔZx, as shown in FIG. This results in a displacement of .

As is clear from the above detailed description, the laminated piezoelectric actuator of this embodiment utilizes bending displacement in addition to thickness direction displacement, so the magnitude of the applied voltage and the piezoelectric element 1
Even without changing the number of laminated sheets, a larger displacement than the conventional one can be obtained.

It should be noted that the present invention is not limited to the embodiments described above, and modifications can be made without departing from the spirit thereof.

[Effects of the Invention] As is clear from the above detailed description, the multilayer piezoelectric actuator of the present invention utilizes bending displacement in addition to displacement in the thickness direction, so the magnitude of the applied voltage and the number of laminated piezoelectric elements are Even without changing the amount of displacement, a larger amount of displacement than the conventional one can be obtained.

[Brief explanation of drawings]

1 to 4 show embodiments embodying the present invention; FIG. 1 is a cross-sectional view showing the structure of the laminated piezoelectric actuator of this embodiment, and FIG. 2 is a side view of the piezoelectric element. , FIG. 3 is a side view of the piezoelectric element after displacement, and FIG. 4 is a sectional view showing the configuration of the laminated piezoelectric actuator after displacement. Further, FIG. 5 is a cross-sectional view showing the structure of a conventional laminated piezoelectric actuator. In the figure, 1 is a piezoelectric element, 8 and 9 are conductive rubber, and 11 is a rigid substance.

Claims (1)

[Claims] 1. A plurality of piezoelectric elements each having a convex portion formed on one side and a concave portion formed on the other side are bonded together by bonding the convex portions to each other with a rigid material in between, and further bonding the concave portions to each other to form a piezoelectric element group. The piezoelectric element group is surrounded by a conductive stretchable member having conductivity and stretchability, and voltages of different polarities are applied to the convex side and the concave side through the conductive stretchable member to vibrate. A multilayer piezoelectric actuator.