JPH11136968A - Ultrasonic drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the friction of the vibration piece and the movement body of an ultrasonic motor, and to obtain accurate positioning by the ultrasonic motor for a long period of time. SOLUTION: In an ultrasonic driven device which is provided with an ultrasonic vibration body 2, an ultrasonic motor 1 with a vibration piece 3 elliptically vibrating with the vibrations of the ultrasonic vibration body 2, and a movement body 5 driven by the ultrasonic motor 1, each of the contacting surfaces of the vibration piece 3 of the ultrasonic motor 1 and the movement body 5 is formed by fine ceramics or cermet, and at the same time a wear resistance layer 4 consisting of hard carbon is provided on at least one of the both contacting surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic drive device for driving a moving body that moves linearly or rotationally by an ultrasonic motor.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic motor has a small size and is driven by friction, so that a large driving force can be obtained, and a small vibration amplitude enables high-resolution positioning. Because of these characteristics, development as a driving means for a moving body that moves linearly or rotationally is being promoted.

The structure of a general ultrasonic motor is as follows.
It is composed of an ultrasonic vibrator using a piezoelectric material as a driving material, and a vibrating piece for transmitting vibration energy of the ultrasonic vibrator to a moving body. Various ideas have been devised for the shape, structure or material of the vibrating body.

[0004] In such an ultrasonic motor, the following characteristics are required of the vibrating piece driven by friction with the moving body.

The vibrating reed of the ultrasonic motor is made of polyimide because it is excellent in abrasion resistance against friction drive with the moving body, does not adhere to the moving body, and does not damage the moving body which is a mating member. Some were formed of resin or glass, or ceramics such as alumina or silicon carbide (Japanese Patent Laid-Open No. 4-105575, Japanese Utility Model Application Laid-Open No. 2-944).
No. 86).

However, when the moving body is driven by the ultrasonic motor, a large impact force is applied between the vibrating piece vibrating at a high speed and the moving body. There is a problem in that it is easily softened by frictional heat and adheres to a moving body.

In the case where the vibrating reed is formed of glass or ceramics having better wear resistance than the polyimide resin, the abrasion of the vibrating reed itself can be suppressed, but the amount of wear of the moving body as the mating member increases. However, any of those using the vibrating reed was not sufficiently satisfactory as a driving means.

Further, such a problem is that if the combination with the material constituting the moving body is bad, the life is further shortened. For example, when both the vibrating reed and the moving body of the ultrasonic motor are formed of glass or ceramics, the abrasion of both of the vibrating reed and the moving body is more intense than when either the vibrating reed or the moving body is formed of a polyimide resin.

For this reason, this ultrasonic drive device is, for example,
When used as a positioning device for measurement, the contact surface between the vibrating reed of the ultrasonic motor and the moving body is worn out in a short period of time, and the contact pressure changes. When used in the process,
There is a disadvantage that the abrasion powder adversely affects the wafer as particles.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides an ultrasonic motor having a vibrating piece that performs elliptical vibration in accordance with the vibration of an ultrasonic vibrator, and an ultrasonic motor driven by the elliptical vibration. And a contact surface of the vibrating piece of the ultrasonic motor and the moving member are each formed of dense ceramics or cermet, and at least one of both contact surfaces. A wear-resistant layer made of hard carbon is provided on one of the sides.

Further, the present invention provides a ceramic or cermet having a Vickers hardness of 13GP, which constitutes the contact surface of the vibrating reed and the moving body of the ultrasonic motor.
a or more.

[0012]

According to the present invention, at least the contact surface between the vibrating piece of the ultrasonic motor and the moving body is formed of dense ceramic or cermet having high strength and high hardness. The vibration energy can be transmitted with a constant contact pressure without deformation of the vibrating reed and the moving body in the above, so that a large driving force and high-resolution positioning accuracy can be realized.

Further, the present invention provides an ultrasonic motor, comprising: a vibrating reed and / or a moving body which is made of a hard carbon material having a higher abrasion resistance than that of the dense ceramic or cermet on at least one of the contact surfaces. Due to the wear layer, the vibrating reed can be connected to the moving body by virtue of the excellent wear resistance of each material and the self-lubricating action of hard carbon even in severe friction drive with the vibrating reed vibrating at high speed. Attack at the time of contact can be suppressed, and wear of both the ultrasonic motor and the moving body can be significantly reduced.

[0014]

Embodiments of the present invention will be described below.

FIG. 1A is a plan view showing an embodiment of the ultrasonic driving apparatus according to the present invention, and FIG.
It is a line sectional view.

In FIG. 1, reference numeral 1 denotes an ultrasonic motor, which comprises an ultrasonic vibrator 2 made of a rectangular parallelepiped piezoelectric material, and a cylindrical vibrating piece 3 attached to an end face of the ultrasonic vibrator 2. , The tip surface of which is a contact surface. The vibrating reed 3 is formed of dense ceramics or cermet, and has an abrasion-resistant layer 4 made of hard carbon on its contact surface.

On the other hand, reference numeral 5 denotes a moving body made of dense ceramic or cermet via a linear bearing 7 attached along the axial direction to a side surface of a guide shaft 6 made of a plate-like body having a rectangular cross section. It is movable. An impact member 8 having an L-shaped cross section is installed on a lower side surface of the guide shaft 6, and the ultrasonic motor is disposed between a wall 9 of the impact member 8 and the moving body 5. 1 is arranged.

A pin 10 having a conical tip is inserted into a through-hole 9a formed in the wall 9 of the impact member 8, and the ultrasonic vibration body 2 is located on the side opposite to the vibrating piece 3. The tip of the pin 10 is brought into contact with the conical concave portion 2a formed on the end surface of the pin 10 and between the flange 10a provided on the peripheral edge of the tip of the pin 10 and the wall 9 of the stopper member 8. The ultrasonic motor 1 is pressed against the moving body 5 by arranging the coil 11 on the moving body 5.

When a voltage is applied to the ultrasonic vibrator 2 of the ultrasonic motor 1 to cause elliptical vibration in a certain direction, this vibration energy is transmitted to the moving body 5 through the vibrating piece 3. The moving body 5 can be smoothly driven by friction. Also, if the phase of the voltage applied to the ultrasonic vibrator 2 is shifted by 90 °, the moving body 5 can be moved in the opposite direction, and if the application of the voltage to the ultrasonic vibrator 2 is stopped, the ultrasonic motor Since one vibrating piece 3 contacts the moving body 5, the moving body 5 can be positioned at a predetermined position.

Further, according to the present invention, since the vibrating reed 3 and the moving body 5 of the ultrasonic motor 1 are formed of dense ceramics or cermet having high hardness and high rigidity, the frictional driving during the friction drive is performed. Since the vibrating reed and the moving body are hardly deformed and the vibration energy can be transmitted with a constant contact pressure, a sufficient driving force can be obtained, and accurate and high-resolution positioning can be performed.

When both the vibrating reed 3 and the moving body 5 of the ultrasonic motor 1 are made of ceramics or cermets or a combination of ceramics and cermets, the ceramics and cermets have high strength and high hardness. Both wear significantly, but according to the invention,
Since the wear-resistant layer 4 made of hard carbon having higher hardness and a self-lubricating action than the dense ceramics or cermet is provided on the contact surface of the vibrating reed 3 of the ultrasonic motor 1, Intense friction drive with
Due to the excellent wear resistance of each material and the self-lubricating action of hard carbon, the attack when the vibrating reed 3 comes into contact with the moving body 5 is suppressed, and the wear of both the ultrasonic motor 1 and the moving body 5 is greatly reduced. Can be reduced.

Therefore, if this ultrasonic drive device is used as a positioning device for measurement used in, for example, a manufacturing process of a semiconductor device, high-resolution positioning of the moving body 5 having a mounting table for a semiconductor wafer can be performed. In addition, since it can be reliably moved to a predetermined position at a high speed, more accurate measurement can be performed, and the measurement time can be shortened. Moreover, the vibrating reed 3 of the ultrasonic motor 1 and the moving body 5
Since there is almost no abrasion due to the frictional drive, high-precision positioning can be realized even in long-term use, and the abrasion powder does not adversely affect the semiconductor wafer as particles.

By the way, as a material constituting the vibrating reed 3 and the moving body 5 of the ultrasonic motor 1, as described above, deformation of each member at the time of friction driving is prevented, and a change in contact pressure is suppressed. From the viewpoint of reducing abrasion, those having high hardness are good, and the Vickers hardness is 13
Those having GPa or more are preferred.

As a specific material, in the case of ceramics, ceramics such as alumina, partially stabilized zirconia, silicon nitride, silicon carbide, zirconia-containing alumina, alumina-containing zirconia, and alumina-titanium carbide can be used. In the case of cermet, TiC-based cermet, TiN-based cermet, and TiCN-based cermet can be used.

As shown in Table 1, these ceramics and cermets have a high hardness of almost Vickers hardness of 13 GPa or more except for a part thereof and a bending strength of 30 kg / mm ² or more. 3 and the moving body 5 can be suitably used.

[0026]

[Table 1]

[0027]

[Table 2]

On the other hand, the hard carbon constituting the wear-resistant layer 4 is 1160 ± 40 c
m ^-1 , 1340 ± 40 cm ^-1 and 1500 ± 60 cm ^-1
Are peaks at any of
340 has a peak at ± 40 cm ^-1 and 1500 ± 60cm ^-1, and 1500 ± 60cm ^-1 at the carbon of amorphous structure having the main peak, diamond-like hard carbon, i- carbon, diamond-like carbon (DLC) , Pseudo diamonds, 1160 ± 40c
crystalline structure carbon having peaks at m ^-1 , 1340 ± 40 cm ^-1 and 1500 ± 60 cm ^-1 and having a main peak at 1340 ± 40 cm ^-1 or 1340
A diamond having a peak only at ± 40 cm ^-1 .

As shown in Table 2, these hard carbons have a Vickers hardness of 3000 kg / cm ² or more, and the carbon or diamond having a crystalline structure has a Vickers hardness of 8000 kg / cm ² or more. Because of its high hardness, the wear of the wear-resistant layer 4 during friction drive with the moving body 5 can be drastically reduced, and since the hard carbon has a self-lubricating effect, it can suppress the attack on the partner member and move. Wear of the body 5 can also be reduced.

As means for forming the wear-resistant layer 4 made of such hard carbon, an ion plating method, a sputtering method, a plasma CVD method, or a magnetic field is applied to a plasma generation region on the contact surface of the vibrating piece 3. The film is formed by a thin film forming means such as an ECR plasma CVD method, or hard carbon is formed into a thick film by the thin film forming means using carbon or the like as a base material, and then the base material is removed to remove hard carbon. After taking out the chip, it may be attached to the contact surface of the vibrating piece 3 with an adhesive or the like.

When hard carbon is formed by thin film forming means, residual stress is generated inside the film, and if the film is too thick, it is peeled off.
m. In addition, when the wear-resistant layer 4 is diamond, the film is generally formed at a high temperature. Therefore, it is desirable that the vibrating reed 3 be formed of a ceramic having a low coefficient of thermal expansion such as silicon carbide or silicon nitride.

As described above, in the present embodiment, the example in which the wear-resistant layer 4 made of hard carbon is provided on the vibrating piece 3 of the ultrasonic motor 1 has been described, but the wear-resistant layer 4 is provided on the contact surface of the moving body 5. May be formed, and furthermore, the wear-resistant layer 4 may be formed on both the vibrating reed 3 and the moving body 5 of the ultrasonic motor 1.

In this embodiment, a drive device that moves linearly has been described as an example, but it is needless to say that the present invention can be applied to an ultrasonic drive device that rotates.

Further, the ultrasonic driving device of the present invention can be applied to all ultrasonic motors 1 that can drive the moving body 5 by elliptical vibration regardless of the type of vibration of the ultrasonic motor 1.

(Embodiment) A test machine shown in FIG. 2 was prepared, and the amount of wear of each of the materials constituting the vibrating reed 23 and the moving body 25 of the ultrasonic motor 21 was measured.

In the tester shown in FIG. 2, a composite vibration type ultrasonic vibrator 22 composed of a vertically vibrating piezoelectric material 22a and a laterally vibrating piezoelectric material 22b, Attach an ultrasonic motor 21 having a cylindrical vibrating piece 23 having a hemispherical tip on the end face,
The supporting base 26 and the moving body 25 are set to have a spring constant of 3 kg.
/ Cm ² , the vibration piece 23 of the ultrasonic motor 21 is attached to the moving body 25.
Are abutted perpendicularly to. Then, a voltage was applied to the ultrasonic vibrating body 22, and the driving frequency was set to 40 KHz, and the vibration was performed for one hour.

In this experiment, the moving body 25 was made of stainless steel (SUS304), alumina ceramics having a purity of 99.5%, hard carbon A, hard carbon B, and hard carbon C. Piece 23
Were formed using polyimide resin and alumina ceramics having a purity of 99.5%.

The hard carbon A means that the base material of the moving body 25 is formed of silicon nitride ceramics, and that the abutment with the vibrating piece 23 is provided at 1160 ± 40 cm ⁻¹ , 1340 ± ¹ 40 cm ^-1 , 1
Having a peak at 500 ± 60 cm ⁻¹ and 1340 ± 4
A hard carbon layer is formed by coating a crystalline carbon film having a main peak of 0 cm ^-1 as an abrasion resistant layer 24. At the contact part, 1340 ± 40 cm ⁻¹ and 1500 ± 60 in Raman spectrum
has a peak at cm ^-1, it is an amorphous carbon film having a 1500 ± 60cm ^-1 to the main peak obtained by coating the wear-resistant layer 24.

The hard carbon C is obtained by forming the base material of the moving body 25 from alumina ceramics and bonding a diamond crystal as a wear-resistant layer 24 to a contact portion with the vibrating piece 23 by bonding. It is.

The results are as shown in Table 3.

[0041]

[Table 3]

As a result, the sample No. using the vibrating piece 23 using a polyimide resin and the moving body 25 using stainless steel and alumina ceramics was used. In 1 and 2, both the moving body 25 and the vibrating piece 23 were significantly worn.

A sample No. using alumina ceramics for the vibrating piece 23 and stainless steel and alumina ceramics for the moving body 25 was used. In Samples Nos. 5 and 6, sample Nos. 5 and 6 were driven by friction between high hardness materials. Worn even more than 1 and 2. In particular, the sample No. It can be seen that when the vibrating reed 23 and the moving body 25 are formed of the same material as shown in 6, the wear is severe.

On the other hand, a sample No. using a polyimide resin for the vibrating piece 23 and hard carbon A and hard carbon B for the moving body 25 was used. In Nos. 3 and 4, although the wear of both the moving body 25 and the vibrating piece 23 could be reduced, the wear of the vibrating piece 23 could not be sufficiently suppressed because the hardness of the polyimide resin was too small.

On the other hand, the vibrating reed 23 is made of alumina ceramics, and the moving body 25 is made of hard carbon A, hard carbon B,
Sample No. using hard carbon C Nos. 7 to 9 have a wear amount of the moving body 25 of 3 mg or less and a vibrating piece 23 due to the self-lubricating action of the hard carbons A to C.
It was found that the abrasion amount of each of them could be reduced to 11 mg or less, and a stable contact pressure was obtained over a long period of time.

Next, the sample No. in Table 2 was used. In the 7 combinations, the wear amount when the hardness of the base material (silicon nitride ceramics) constituting the moving body 25 was changed was measured under the same conditions as in Example 1.

The results are as shown in Table 4.

[0048]

[Table 4]

As a result, it can be seen that the greater the hardness of the base material (silicon nitride ceramics) forming the wear-resistant layer 24, the smaller the amount of wear of the moving body 25 and the vibrating piece 23 can be. Then, the hardness of the base material is 13 GPa in Vickers hardness.
By doing so, the wear amount of the moving body 25 and the vibrating piece 23 could be reduced to single digits.

Although only one example is shown in the present embodiment, the same tendency is observed when the vibrating piece 23 and the moving body 25 of the ultrasonic motor 21 are made of another ceramic or cermet.

[0051]

As described above, according to the present invention, an ultrasonic motor provided with a vibrating piece that performs elliptical vibration with the vibration of an ultrasonic vibrator, and a moving body driven by the elliptical vibration of the ultrasonic motor. In the ultrasonic drive device provided with, the contact surface of the vibrating piece of the ultrasonic motor and the moving body is formed of dense ceramics or cermet, respectively, and at least one of both contact surfaces is hard. The provision of a wear-resistant layer made of carbon enables the transmission of vibration energy from the ultrasonic motor without loss, realizing a large driving force and high-resolution positioning accuracy. Wear of both the piece and the moving body can be significantly reduced.

For this reason, the ultrasonic driving apparatus of the present invention is provided with an X-
If used for a Y table, a static pressure linear guide device, or a rotary positioning device, high-precision positioning can be performed over a long period of time.

[Brief description of the drawings]

FIG. 1A is a plan view showing an embodiment of an ultrasonic driving device according to the present invention, and FIG. 1B is a sectional view taken along line XX of FIG. 1A.

FIG. 2 is a schematic diagram showing a test machine.

[Explanation of symbols]

1. Ultrasonic motor, 2. Ultrasonic vibrator, 3.
..Vibration bars, 4 ... abrasion resistant layers, 5 ... moving bodies, 6 ...
..Guide shaft, 7: linear bearing, 8: stopper member, 9: wall portion of stopper member, 10: pin, 1
1 ... coil

Claims (2)

[Claims] 1. An ultrasonic drive device comprising: an ultrasonic motor having a vibrating piece that performs elliptical vibration in accordance with the vibration of an ultrasonic vibrator; and a moving body driven by the elliptical vibration of the ultrasonic motor. The contact surfaces of the vibrating reed and the moving body of the ultrasonic motor are each formed of dense ceramics or cermet, and at least one of both contact surfaces is provided with a wear-resistant layer made of hard carbon. An ultrasonic driving device characterized by the above-mentioned. 2. The ultrasonic wave according to claim 1, wherein the Vickers hardness of the dense ceramic or cermet constituting the contact surface of the vibrating reed and the moving body of the ultrasonic motor is 13 GPa or more. Drive.