JPS6370466A - Actuator - Google Patents

Abstract

PURPOSE:To improve durability in repetitive use, by forming a monomorph type piezoelectric element with porcelain having a specified composition. CONSTITUTION:Porcelain, which is expressed by the Formula (I) has a perovskite type crystal structure. As A, alkali metal such as lithium and cesium are listed. As B, bismuth, gallium and the like are listed. As C, titanium, tin and the like are listed. The porcelain further includes silicon dioxide and aluminum oxide as additives. The raw material powder of the porcelain expressed by the Formula (I) can be manufactured by a solid phase reaction method or a coprecipitation method. In the solid reaction method, e.g., a carbonate of the element in A, oxides of the elements in B and C and the like are mixed into the powder of lead oxide and the powder of zirconium oxide, and the mixture is temporarily burned and crushed. In the coprecipitation method when lead-zirconium-titanium elements are used, oxalic acid and the like are added to mixed aqueous solution of water soluble salt such as nitrate and hydrochloride. Precipitation is performed and temporary burning and crushing are performed. Thus durability in repetitive use is improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is particularly applicable to precision machinery, including fluid flow control valves and their valves. drive sources for optical path length control, piezoelectric buzzers, and pressure '41 speakers.

There are some related to actuators that can be used as vibrators such as ultrasonic agitators. In other words, wood grain m
In i, ``actuator 1'' is used as a general term not only for elements that displace other objects with which they are in contact, but also for elements that move themselves.

[Conventional technology and its problems] Conventionally, the deflection of piezoelectric ceramics has been measured in two ways] Uses-1) As a wood, a piece of piezoelectric thin plate porcelain that has been subjected to polarization treatment is pasted to a fixed electrode plate (shim). Unimorph types and bimorph types in which piezoelectric thin plate porcelain is bonded to both sides of a shim are known. However, these piezoelectric elements have problems such as depolarization due to high negative voltage or long-term application of negative voltage, and peeling of the adhesive between the ceramic and the electrode material, resulting in low durability for repeated use.

Therefore, in recent years, Ferroelectrics, 57゜203-2
20 (1984), research on polymer piezoelectric elements using polyvinylidene fluoride as a raw material is active. This is because these elements do not require the piezoelectric element to be glued as in the bimorph type, and exhibit the piezoelectric effect as a single plate (monomorph type), so they have the potential to overcome the problems of piezoelectric ceramic elements. It is. However, these polymer piezoelectric elements still have problems such as the amount of displacement being smaller than that of piezoelectric ceramic elements, and the elements themselves being soft, making it difficult to transmit displacement to others.

[Means for Solving the Problems] As a result of extensive studies from the above viewpoints, the present inventors have formulated the following general formula (I) (Pb, AB) (Zr, C)031
/2 1/2 1-n n...(I) (However, A is a monovalent element, B is a trivalent element, and A,
Both B are elements that can replace lead as solid solution, and C is an element that can replace zirconium as solid solution. Further, n represents a number from ◯ to 0.8. ) It was discovered that the porcelain represented by the formula becomes a monomorph type piezoelectric element, and the present invention was completed. The present invention will be explained in detail below.

The porcelain represented by the general formula (I) has a Bef Kovskite type crystal structure, where A is a monovalent element and B is a trivalent element, and both A and B can replace lead as solid solution. It must be an element. In general, C must be an element that can replace and dissolve zirconium. As such elements,
First, A is lithium, sodium, potassium, and rubidium.

Alkali metals such as cesium, B is bismuth,
Examples of C include lanthanum, iso-1-lium, antimony, and gallium. Examples of carbon include ditanium and tin.

Raw material powders used in the production of porcelain represented by the general formula (I), such as lead oxide (PbO) powder and zirconium oxide (
In the case of the so-called solid phase reaction method or the lead-zirconium-ditanium system, in which carbonate of element A, oxide of element B and C, etc. are mixed with ZrO2) powder, calcined, and pulverized.
Adding oxalic acid, etc. to a mixed aqueous solution of water-soluble salts such as nitrates and hydrochlorides to form a precipitate, which is then calcined and pulverized.
It can be produced by a so-called coprecipitation method.

The actuator of the present invention can also be used by adding silicon dioxide M (S i 02 ) or aluminum oxide (A1203) as a sintering aid to the raw material powder thus obtained.

The production of the porcelain represented by the general formula (I), which is the material of the actuator of the present invention, employs processes such as weighing, mixing, drying, molding, and sintering of raw material powders, similar to the production method for porcelain Z2 in general. do it. Mixing methods include ball mills, vibration mills, etc., and molding methods include mold presses and rubber presses.

Cast molding, injection molding, tape molding, etc. can be used. Although sintering is difficult depending on the components and composition contained in the molded body, the
It may be carried out by holding it for a certain period of time, and the atmosphere at that time may be air.

[Function 1] The actuator of the present invention bends even though it is a single plate that is not subjected to polarization treatment, that is, it is of a monomorph type. The reason for this deflection is not clear, but it is thought that, for example, space charges form at grain boundaries, which causes a peculiar phenomenon. In other words, when the 'Fi poles are attached to both sides of the actuator of the present invention and an electric field is applied, the barrier near one of the bonded surfaces becomes high, a strong electric field is applied locally, and in combination with the ferroelectricity of the porcelain, It is thought that when negative strain occurs and the direction of the electric field is reversed, a similar phenomenon occurs on the other bonded surface, resulting in the observation of deflection of the porcelain.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these.

Examples 1-14. Comparative Example 1 Each raw material powder shown in Table 1 was weighed and dissolved in ethanol for 24 hours.
Mixed by ball mill for an hour. After drying, 1.5t/
At pressures c and d, the length is about 48#I and the width is about 18J11. It was molded into a plate with a thickness of about 10 am.

Next, this plate was sintered in air at a temperature of 1200°C for 1 hour, and cut parallel to the plane corresponding to the above-mentioned approximately 48aw x approximately 18m. The actuator is made of porcelain.

Subsequently, a silver paste was applied to the surface of this porcelain and baked in air at a temperature of 800° C. for 1 hour, and electrodes were attached.

Fix one end (9NR) of the actuator in the length direction (portion D in Fig. 1) to which this electrode is attached, and
An electric field of K V / cm was applied, and the amount of displacement from the fixed point at positions 28 (position △ in Figure 1), 19NR (position B in Figure 1), and 9# (position C in Figure 1) was measured. was measured using an eddy current non-contact sensor. The results are not shown in Table 1.

Also, the actuator fixed as described above is
When an alternating current of 10 V was applied, the actuator vibrated at the same frequency as the alternating current in all Examples except Comparative Example 1.
It emitted a sound wave at that frequency.

4 drawing l! I Simple Explanation Figure 1 is a conceptual diagram showing the length and width of the actuator element, measurement points for deflection, and fixed parts in a live uterus.

△, B, C: Deflection measurement points D: Fixed part Patent applicant: Toyo Fudatsu Kogyo Co., Ltd. Procedural formalities (method) December 17, 1986

Claims (3)

[Claims] (1) In an actuator consisting of a monomorph type piezoelectric element, the piezoelectric element has the following general formula (Pb, A_1_/_2B_1_/_2) (Zr_1_
-_n, Cn) O_3 (However, A is a monovalent element, B is 3
An element that is a valent element and can replace lead with solid solution in both A and B,
C is an element that can replace zirconium and form a solid solution. Also, n
represents a number from 0 to 0.8. ) is a porcelain actuator. (2) In the general formula, the monovalent element represented by A is lithium, sodium, potassium, rubidium or cesium, and the trivalent element represented by B is bismuth, lanthanum, yttrium, antimony or potassium, C
The actuator according to claim (1), wherein the element which can be substituted and solid-solubilized with zirconium represented by is titanium or tin. (3) The actuator according to claim (1) or (2), wherein the porcelain represented by the general formula contains silicon dioxide or aluminum oxide as an additive.