JP2003235275A - Mover for surface acoustic wave actuator and surface acoustic wave actuator using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mover for a surface acoustic wave actuator capable of improving a contact area largely influencing a driving performance and the number of projections per area, improving durability, and being easily manufactured, and to provide a surface acoustic wave actuator using the same. <P>SOLUTION: On the contact surface of a mover where the mover contacts a stator, a film 13 made of a material having a hardness higher than that of a base material 12 is formed on the material 12 having a plurality of columnar projections thereon, thereby forming the projections by the material 12 and the film 13. Abrasion can be reduced and an absorption phenomenon can be solved by a decrease in contact stress by an increase in radius of curvature of the corner part of each projection part caused by film deposition and the characteristics of the film material, it can focus on improvement of projection density of the contact surface with respect to the base material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving element in a surface acoustic wave actuator and a surface acoustic wave actuator using the moving element.

[0002]

2. Description of the Related Art Surface acoustic wave actuators are compact, capable of high-speed, high-thrust driving and precise positioning.
It is expected to be realized as a small linear actuator. FIG. 5 is a diagram showing the basic configuration of the surface acoustic wave actuator. IDT (Inter Digital) on both sides
Transducer) 2 and 3 formed stator 1
The moving element 4 is mounted on the moving element 4, and the moving element 4 is provided with an elastic force supply source 11 for applying a predetermined pressing force in advance.
As for the performance of the surface acoustic wave actuator, in the report of the 21st Symposium on the Basics and Applications of Ultrasonic Electronics, page 275 of the report, a silicon mover with a large number of columnar protrusions on the contact surface was applied with a force of 80N. It is shown that a driving force of about 8 N can be obtained by pressing the surface acoustic wave element. At the same time, it is also shown that when the contact area is the same, the obtained driving force is improved by increasing the number of protrusions per area and increasing the pressing force.

[0003]

The silicon mover in the above-mentioned proceedings is provided with a large number of columnar protrusions on the contact surface with the stator, but since the protrusions are manufactured by the dry etching process. , The corners of the tips of the protrusions are almost unrounded. Therefore, if the mover is continuously driven, the corners of the protrusions cause abrasive wear by digging up the surface of the stator, which poses a serious problem in terms of durability of the actuator. Further, since the contact stress at the corners is high, there is a problem that the moving element is attracted to the stator due to repeated friction between the tip of the protrusion and the stator. On the other hand, JP-A-7-23
In a moving element using an iron ball as a projection as shown in Japanese Patent No. 1685 and a moving element manufactured by a manufacturing method as disclosed in Japanese Patent Laid-Open No. 2000-69773, the radius of curvature is large with respect to abrasive wear and adsorption. It is effective because it can be done, but there is a limit in terms of the contact area, the number of protrusions per area, and the ease of manufacturing.

In view of the above points, the present invention can improve the contact area and the number of protrusions per area that greatly affect the driving performance, and further improve the durability of the surface acoustic wave actuator. An object of the present invention is to provide a moving element for a surface acoustic wave actuator which is easy to manufacture and a surface acoustic wave actuator using the same.

[0005]

In order to solve the above-mentioned problems, a surface acoustic wave actuator moving element according to the present invention comprises a base material having a plurality of columnar projections formed on a contact surface with a stator. In addition, a film made of a material having a hardness higher than that of the base material is formed. By configuring the protrusions with a base material and a hard film, it is possible to reduce the contact stress due to the increase in the radius of curvature of the protrusion tip corners due to film deposition and to reduce the abrasive wear and eliminate the adsorption phenomenon by the characteristics of the film material. Therefore, the base material can focus on improving the contact area of the contact surface and the number of protrusions per area.

Therefore, according to the present invention, it is possible to increase the contact area and the number of protrusions per area that greatly affect the driving performance, and further improve the durability of the surface acoustic wave actuator. A moving element for a surface acoustic wave actuator that is easy to obtain is obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is such that a surface acoustic wave which is pressed against a stator having a surface acoustic wave excitation means and propagates on the stator causes a frictional force to be generated. In the surface acoustic wave actuator moving element to which the driving force is applied, the contact surface with the stator is formed by forming a plurality of columnar protrusions on the base material and forming a film made of a material having a hardness higher than that of the base material. It is a moving element for surface acoustic wave actuators that reduces the contact stress due to the increase in the radius of curvature of the tip corner of the protrusion due to film deposition, and reduces the abrasive wear and elimination of the adsorption phenomenon depending on the characteristics of the film material. Since the base material can focus on improving the contact area of the contact surface and the number of protrusions per area, it is possible to improve the driving performance and the durability of the surface acoustic wave. Chueta is obtained.

According to a second aspect of the present invention, in the surface acoustic wave actuator moving element according to the first aspect, the projection shape is a cylinder, and the surface acoustic wave actuator moving element is characterized in that: Since the radius of curvature of the corner portion of the protrusion can be made uniform over the entire circumference, the abrasive wear can be further reduced.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the surface acoustic wave actuator moving element according to
A surface acoustic wave actuator moving element characterized in that the film thickness is between 0.2 times and 1 time the height of the protrusion, and the adhesion and durability of the film can be secured.
The driving performance can be stabilized.

The invention according to claim 4 is the invention according to claims 1 to 3.
In the surface acoustic wave actuator moving element according to
In the surface acoustic wave actuator moving element, the radius of curvature of the corner at the tip of the protrusion having the film formed thereon is larger than the radius of curvature of the corner at the tip of the protrusion of the base material. Since the larger size reduces the abrasive wear, the durability of the surface acoustic wave actuator can be further improved.

The invention according to a fifth aspect is the first to the fourth aspects.
In the surface acoustic wave actuator moving element according to
It is a moving element for a surface acoustic wave actuator characterized in that the material of the base material is silicon, various silicon processes can be used for processing, and the base material can be easily processed at low cost.

The invention according to claim 6 is the same as claims 1 to 5.
A surface acoustic wave actuator that uses the moving element for a surface acoustic wave actuator described in (1) above, and is a surface acoustic wave actuator that has excellent driving performance and improved durability.

According to a seventh aspect of the present invention, in the surface acoustic wave actuator according to the sixth aspect, a film made of a material having a hardness higher than that of the stator is formed on a contact surface of the stator with the moving element. Is a surface acoustic wave actuator characterized by further reducing the wear of the stator,
The durability of the surface acoustic wave actuator can be further improved.

The invention according to claim 8 is the invention according to claims 6 to 7.
It is a magnetic disk device using the surface acoustic wave actuator described in 1 above as a head driving actuator. By using the surface acoustic wave motor of the present invention, a magnetic disk device having excellent access performance can be obtained.

The invention according to claim 9 is the invention according to claims 6 to 7.
It is an optical disk device using the surface acoustic wave actuator described in 1 above as a head driving actuator. By using the surface acoustic wave motor of the present invention, an optical disk device having excellent access performance can be obtained.

Embodiments of the present invention will be described below.

(Embodiment 1) FIG. 1 is a front view and a bottom view of a first embodiment of a moving element for a surface acoustic wave motor according to the present invention. The surface shown in the bottom view is the contact surface with the stator, and is provided with a plurality of cylindrical projections 5. FIG. 2 is a sectional view of the protrusion. As shown in FIG. 2, the mover 4 is composed of a base material 12 and a hard film 13. By depositing the hard film 13 on the base material 12, the radius of curvature of the corner portion of the protrusion tip is increased, concentration of contact stress at the corner portion when contacting the stator is eliminated, and the maximum contact stress is reduced. . This greatly reduces the abrasive wear due to the protrusions. Further, the adsorption phenomenon can be eliminated by depositing a film having excellent lubricity. As a result, the base material can focus on improving the contact area of the contact surface and the number of protrusions per area. As the material of the base material, it is desirable that silicon or the like can be easily processed by using a semiconductor processing process such as a dry etching process. By using the dry etching process, it is possible to easily improve the contact area and the number of protrusions per area. Further, as the material of the hard film, TiN, Ti
C, DLC, SiC, Si ₃ N _{4 and the} like are desirable because they have excellent wear resistance. In particular, DLC is desirable because it has excellent lubricity. Various CVD processes or PVD processes can be used for depositing the hard film, but a sputtering method or the like is preferable in that the film thickness can be increased. The film thickness of the hard film is preferably 0.2 times or more the height of the protrusion in terms of durability of the film, and is preferably 1 times or less the height of the protrusion in terms of adhesion of the film. Further, the radius of curvature may be further increased by preliminarily rounding the tip corners of the protrusions by wet etching or the like and depositing a hard film.

By pressing the contact surface of the moving element 4 against the surface acoustic wave propagating portion of the stator 1 having the surface acoustic wave exciting means 2 and 3 as in FIG. It is possible to obtain a surface acoustic wave actuator having excellent durability and driving performance. The stator is preferably a piezoelectric material. For example, a piezoelectric crystal plate such as LiNbO ₃ can be used, and this is preferable because it has a large electromechanical coupling coefficient. A non-piezoelectric material can also be used by using a piezoelectric thin film such as ZnO as a surface acoustic wave exciting means. At this time, the surface acoustic wave propagating portion corresponding to the contact surface of the stator with the moving element also has TiN, TiC,
Wear on the stator side can be reduced by forming a film of a material that has higher hardness and wear resistance than the stator such as DLC, SiC, Si ₃ N ₄ and is combined with a hard film of the moving element. It is possible to obtain a surface acoustic wave actuator that is further reduced and has further improved durability.

(Second Embodiment) FIG. 3 is a schematic view showing a second embodiment of the surface acoustic wave actuator according to the present invention. As shown in the figure, the head arm 7 is attached to the surface acoustic wave actuator 6 shown in the first embodiment, and the positioning with respect to the magnetic disk 8 is performed. By using the surface acoustic wave actuator according to the present invention as an actuator for driving a head of a magnetic disk, the head can be precisely positioned and a magnetic disk device having excellent access performance can be obtained.

(Third Embodiment) FIG. 4 is a schematic view showing a third embodiment of the surface acoustic wave actuator according to the present invention. As shown in the figure, the optical head 9 is attached to the surface acoustic wave actuator 6 shown in the first embodiment, and the optical disc 10 is positioned. By using the surface acoustic wave actuator according to the present invention as an actuator for driving a head of an optical disc, the head can be precisely positioned, and an optical disc device having excellent access performance can be obtained.

The present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention, which are also included in the present invention.

[0022]

As described above, according to the present invention, in the contact surface of the moving element for the surface acoustic wave actuator with the stator, the hardness is higher than that of the base material on the base material having a plurality of columnar protrusions. By forming a film of material and forming the protrusions with a base material and a hard film, it is possible to reduce the abrasive wear and eliminate the adsorption phenomenon, and the base material has a contact area of the contact surface and the number of protrusions per area. Since it becomes possible to focus on improving the contact surface area, it is possible to improve the contact area and the number of protrusions per area that greatly affect the driving performance, and further improve the durability of the surface acoustic wave actuator. A mover for a surface acoustic wave actuator that is possible and easy to manufacture is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a moving element for a surface acoustic wave actuator according to the present invention.

FIG. 2 is a sectional view of a protrusion in the first embodiment of the present invention.

FIG. 3 is a second surface acoustic wave actuator according to the present invention.
Schematic diagram showing an example

FIG. 4 is a third surface acoustic wave actuator according to the present invention.
Schematic diagram showing an example

FIG. 5 is a diagram showing a basic configuration of a surface acoustic wave actuator.

[Explanation of symbols]

1 stator 2,3 IDT 4 movers 5 protrusions 6 Surface acoustic wave actuator 7 head arm 8 magnetic disks 9 Optical head 10 optical disc 11 Elasticity supply source 12 Base material 13 Hard film

Continued front page    F term (reference) 5H680 AA06 AA12 BB03 BC05 CC08                       DD02 DD23 DD65 FF16 GG14                       GG44

Claims (9)

[Claims] 1. A surface acoustic wave actuator moving body, which is pressed against a stator having surface acoustic wave excitation means and to which a driving force is applied via frictional force from surface acoustic waves propagating on the stator. The surface for contacting with the stator is formed by forming a plurality of columnar protrusions on a base material and further forming a film made of a material having a hardness higher than that of the base material. . 2. The surface acoustic wave actuator moving element according to claim 1, wherein the shape of the protrusion is a column. 3. The surface acoustic wave actuator moving element according to claim 1, wherein the thickness of the film is between 0.2 and 1 times the height of the protrusion. 4. The radius of curvature of the corner portion at the tip of the film-formed protrusion is larger than the radius of curvature of the corner portion at the tip of the protrusion of the base material.
A moving element for a surface acoustic wave actuator according to any one of 1. 5. The moving element for a surface acoustic wave actuator according to claim 1, wherein the material of the base material is silicon. 6. A surface acoustic wave actuator using the moving element for a surface acoustic wave actuator according to claim 1. 7. The surface acoustic wave actuator according to claim 6, wherein a film made of a material having a hardness higher than that of the stator is formed on a contact surface of the stator with the mover. 8. A magnetic disk device using the surface acoustic wave actuator according to claim 6 as a head driving actuator. 9. An optical disk device using the surface acoustic wave actuator according to claim 6 as a head driving actuator.