JPH04146156A - Multilayer piezoelectric actuator - Google Patents

Abstract

PURPOSE:To protect a terminal against breakdown by jointing a highly rigid terminal to an external electrode mounted on a dummy layer while directing in the direction of displacement of a piezoelectric element or perpendicularly thereto. CONSTITUTION:A multilayer piezoelectric actuator comprises a normal layer 1 comprising a plurality of laminated piezoelectric ceramic boards, double layers 2 comprising piezoelectric ceramic boards laminated thicker than the normal layer 1 and jointed to the opposite ends of the normal layer 1, square pillar piezoelectric element bodies 4 including a dummy layer 3 exhibiting no piezoelectricity and jointed to the opposite ends of the double layer 2, external electrodes 5 arranged on two opposing faces, which are perpendicular to the direction of displacement of the piezoelectric element body 4, across the dummy layers 3 at the opposite ends, and rod terminals 6 jointed, respectively, to the external electrode 5 on the dummy layer 3. The terminals 6 are jointed perpendicularly to the direction of displacement of the piezoelectric element and in parallel with the fixing face of the external electrode 5. According to the constitution, an actuator can be positioned and assembled easily in the through-holes of a printed board and the terminals can be protected against breakdown.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminated piezoelectric actuator, sometimes used to drive a printing hammer in a printer.

[Conventional technology]

Conventionally, this type of laminated piezoelectric actuator, as shown in a perspective view of a typical structure in FIG. A square prism piezoelectric element that includes a double layer 2 made of laminated piezoelectric ceramic plates that are thicker than the piezoelectric ceramic plate of the normal layer 1, and a dummy layer 3 that is bonded to both ends of the double layer 2 and has no piezoelectricity. One external electrode 5 is disposed on the main body 4 and the opposite surfaces perpendicular to the displacement direction of the piezoelectric element main body 4, and the external electrode 5 is disposed across the dummy layer 3 at both ends, and the external electrode 5 on the normal layer 1. It has a structure in which lead wires 8 are joined one by one. When a voltage is applied to the lead wire 8, the laminated piezoelectric actuator is displaced in the longitudinal direction indicated by the arrow.

[Problem to be solved by the invention]

In the conventional laminated piezoelectric actuator described above, voltage is applied through the lead wires provided on the normal layer part of the external electrodes provided on both sides of the normal layer, so the lead wires also move during operation, causing the lead wires to There are drawbacks such as destruction due to deformation and a decrease in operating efficiency. Another drawback is that it is difficult to assemble the lead wire into the through hole of the printed circuit board because the lead wire has low rigidity.

[Means to solve the problem]

The laminated piezoelectric actuator of the present invention includes a normal layer in which a plurality of piezoelectric ceramic plates are laminated, and a piezoelectric ceramic plate that is thicker than the piezoelectric ceramic plate of the normal layer, and the laminated plates are bonded to each end of the normal layer. A rectangular prism piezoelectric element body having a double layer consisting of a double layer and a dummy layer without piezoelectricity bonded to each end of the double layer, and two opposing faces perpendicular to the displacement direction of the piezoelectric element body. In a laminated piezoelectric actuator used in a print head of a printer, the actuator has external electrodes disposed extending up to the dummy layer, the piezoelectric actuator being perpendicular to the displacement direction of the piezoelectric element body and parallel to the surface on which the external electrodes are provided. By having terminals bonded to each of the two external electrodes on the dummy layer, the terminals are connected to the dummy layer in the displacement direction of the piezoelectric element body and parallel to the surface on which the external electrodes are provided. It is configured by being a terminal connected to each of two external electrodes on the layer.

〔Example〕

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

FIG. 1 is a perspective view of an embodiment of the present invention. The embodiment shown in FIG. 1 consists of a normal layer 1 made by laminating a plurality of piezoelectric ceramic plates, and a piezoelectric ceramic plate that is bonded to both ends of the normal layer 1 and has a thickness thicker than the piezoelectric ceramic plate of the normal layer 1. A rectangular prism piezoelectric element body 4 that includes a double layer 2 and a dummy layer 3 that is bonded to both ends of the double layer 2 and has no piezoelectricity, and two opposing faces perpendicular to the displacement direction of the piezoelectric element body 4. The dummy layer 3 includes an external electrode 5 disposed across the dummy layer 3 at both ends, and rod-shaped terminals 6 each connected to the external electrode 5 on the dummy layer 3. The terminal 6 is connected perpendicularly to the displacement direction of the piezoelectric element, and the external electrode 5 is attached parallel to the plane.

When a voltage is applied to the terminal 6, the laminated piezoelectric actuator is displaced in the direction of the arrow.

FIG. 2 is a perspective view of another embodiment of the present invention, in which the terminal 6 is perpendicular to the displacement direction of the piezoelectric element in the embodiment shown in FIG. In contrast to the case in which the terminals 7 are joined in the same direction as the displacement direction of the piezoelectric element, and the external electrode 5 is attached parallel to the surface. The rest of the structure is the same as in FIG. 1, and the operation is also the same.

〔Effect of the invention〕

As explained above, the present invention has a structure in which a highly rigid terminal is bonded to an external electrode on a dummy layer in a direction perpendicular to or facing the displacement direction of the piezoelectric element. This has the effect of facilitating positioning and assembly. Furthermore, there is also the effect that there is almost no movement between the terminal and the piezoelectric element body during operation, so that the terminal is less likely to be damaged and the efficiency of the piezoelectric element does not deteriorate.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a perspective view of another embodiment of the present invention, and FIG. 3 is a perspective view of a typical conventional multilayer piezoelectric actuator. 1... Normal layer, 2... Double layer, 3... Dummy layer, 4
... Piezoelectric element body, 5... External electrode, 6.7...
Terminal, 8...Lead wire.

Claims (1)

[Scope of Claims] 1. A normal layer in which a plurality of piezoelectric ceramic plates are laminated, and a piezoelectric ceramic plate in which the thickness of the laminated plates bonded to each end of the normal layer is thicker than the piezoelectric ceramic plate of the normal layer. A rectangular prism piezoelectric element body having a double layer and a dummy layer without piezoelectricity bonded to each end of the double layer, and two opposing faces perpendicular to the displacement direction of the piezoelectric element body. In a laminated piezoelectric actuator used in a print head of a printer having an external electrode disposed extending up to the dummy layer, the piezoelectric actuator is perpendicular to the displacement direction of the piezoelectric element body and parallel to the surface on which the external electrode is provided. A laminated piezoelectric actuator characterized in that it has a terminal connected to each of the two external electrodes on the dummy layer. 2. The terminal according to claim 1 is a terminal bonded to each of the two external electrodes on the dummy layer in the direction of displacement of the piezoelectric element body and parallel to the surface on which the external electrode is provided. Features a multilayer piezoelectric actuator.