JP3500509B2 - Multilayer piezoelectric ceramic actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric actuator for converting electric input energy into mechanical energy such as displacement and force, and more particularly to a structure of internal electrodes thereof. It is. 2. Description of the Related Art Conventionally, in a laminated piezoelectric actuator in which piezoelectric ceramic layers and electrode layers are alternately stacked and displaced in the stacking direction, the cross section of the electrode layer and the cross section of the ceramic prism are the same in order to avoid stress concentration. When the ceramic layer and the electrode layer are alternately stacked, the tensile strength in the stacking direction, which is the displacement direction of the actuator, is
It depends on the bonding strength between the ceramic and the electrode. However, there is no chemical reaction between the ceramic and the electrode in the sintering process, and the bonding strength at the interface is smaller than the chemical bond between the ceramics. Therefore, when the actuator has a low tensile strength in the laminating direction and is pulse-driven for a long time, there is a defect that the actuator is broken at the interface between the electrode and the ceramic due to repeated expansion and contraction. In addition, there is a drawback that a large amount of noble metal is used and the cost is high because of the entire surface electrode. [0003] The present invention eliminates the above disadvantages, has a high tensile strength in the laminating direction, is highly reliable by using pulse driving, is low in cost, and has a predetermined displacement or force. Is intended to provide a laminated piezoelectric actuator capable of obtaining the following. According to the present invention, there is provided a laminated piezoelectric actuator which generates mechanical energy such as displacement or force in a longitudinal direction when a voltage is applied, comprising a piezoelectric ceramic sheet and an electrode layer. Are laminated alternately, and in a prismatic laminated piezoelectric actuator displaced in the laminating direction,
The electrode layer is a plurality of strip-shaped electrodes formed on a plane orthogonal to the lamination direction, and has a line electrode connecting the strip-shaped electrodes,
In addition, a laminated piezoelectric ceramic actuator is obtained in which the band-shaped electrodes, which are exposed on the side surfaces at the two opposing surfaces of the band-shaped electrodes, are formed for each layer so as to be connected to the external electrodes forming the counter electrodes. According to the electrode structure of the present invention, the ceramic layers above and below the belt-like electrode are bonded to each other at portions other than the electrode. Larger than the structure. Further, since the electrode layer is a strip-shaped electrode as compared with the conventional full-surface electrode, the amount of the noble metal used can be reduced, and the cost can be reduced. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the laminated piezoelectric actuator of the present invention. In FIG. 1, 1 is a ceramic layer, 2 is an electrode pattern A, 3 is an electrode pattern B, 4 is an external electrode, 5 is a strip electrode, and 6 is a line electrode. For the ceramic layer 1, the chemical composition formula is P
A green sheet having a thickness of 120 μm was prepared using b (Ni · Nb) · Ti · Zr · O ₃ -based piezoelectric ceramics. Next, using silver-palladium-based electrode paste, internal electrode patterns A2 and B3 as shown in FIG. 1 were printed on the green sheet by screen printing. Further, a layer on which the electrode pattern A2 was printed and a layer on which the electrode pattern B3 was printed were alternately and repeatedly laminated into 150 layers, and unprinted green sheets were laminated on the upper and lower sides by 20 layers each. After that, it is thermocompressed and measures 2.4m.
An unsintered ceramic laminate of mx 3.5 mm x 23.5 mm was obtained. The laminate is de-bindered and removed in air at 110
Sintering was performed at 0 ° C., and external electrodes 4 were formed on two side surfaces of the obtained sintered body where the internal electrode layers were exposed, to obtain a laminated piezoelectric actuator. A prototype piezoelectric actuator of dimensions 2 mm.times.3 mm.times.20 mm and a conventional piezoelectric actuator of dimensions 2 mm.times.3 mm.times.20 mm.
The capacitance, the displacement, and the tensile strength were measured using a piezoelectric actuator of mm × 3 mm × 20 mm, and a continuous pulse test was performed. The measurement results are shown in Table 1 below. [Table 1] As is apparent from Table 1, the piezoelectric ceramic actuator having the structure according to the present invention has a higher tensile strength than that of the conventional structure, and can provide a performance that can sufficiently withstand repeated expansion and contraction of the actuator during continuous pulse driving. According to the present invention, there is provided a laminated piezoelectric actuator having a large tensile strength, high reliability under continuous pulse driving, low cost, and capable of obtaining a predetermined amount of displacement or force. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a multilayer piezoelectric actuator according to one embodiment of the present invention. [Description of Signs] 1 Ceramic layer 2 Electrode pattern A 3 Electrode pattern B 4 External electrode 5 Strip electrode 6 Wire electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-336928 (JP, A) JP-A-5-90657 (JP, A) JP-A-7-135346 (JP, A) JP-A-6-135346 281473 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 41/083

Claims (1)

(57) [Claim 1] In a prismatic laminated piezoelectric actuator in which piezoelectric ceramic sheets and electrode layers are alternately laminated and displaced in the laminating direction, the electrode layers are orthogonal to the laminating direction. A plurality of strip-shaped electrodes formed on a plane, the strip-shaped electrodes having line electrodes connecting the strip-shaped electrodes, and the strip-shaped electrodes exposed to the side surfaces on two opposing surfaces of the strip-shaped electrodes are opposed to each other for each layer. A multilayer piezoelectric ceramic actuator formed so as to be connected to an external electrode forming a piezoelectric actuator.