JPH063788B2 - Fine motion rotary drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is directed to a mask mounting turntable of an exposure apparatus for ICs and LSIs, a sample stage such as an electron microscope and an electron beam analyzer, or engineering equipment. The present invention relates to a fine movement rotation drive device that can be used for rotation drive of a rotation adjusting unit such as a mirror and a prism.

(B) Prior art Circuit patterns such as ICs and LSIs are becoming finer year by year in order to increase the degree of integration. For aligning the mask of the exposure apparatus, for example, a turntable with an angular accuracy of 0.1 second or less is used. It is required to use a rotation drive device capable of driving the above.

BACKGROUND ART Conventionally, as a rotary drive device suitable for fine movement operation, a gear reducer using a worm or the like, a harmonic reducer, and the like are known.
However, the gear reducer using a worm or the like has a large backlash and cannot secure high positioning accuracy because of the surface roughness of the contact surface. On the other hand, the harmonic reducer can be expected to have higher accuracy than the gear reducer, but this is not completely free of backlash. Since the rigidity is relatively low, it is best to obtain an accuracy of about 10 seconds.

Therefore, recently, a fine movement rotation drive device as shown in FIGS. 1 and 2 has been developed. That is, in this device, a pair of semi-circular plates a and b are connected via elastic hinges c, and piezoelectric elements d and e are provided at both ends of the facing gap between the semi-circular plates. The body f is rotatably provided on the base g. Further, brakes h and i for fixing the semi-circular plates a and b to the base g by utilizing expansion and contraction of a piezoelectric element (not shown) are provided. Then,
In the operation of this device, first, only the first brake h is operated (the operating brake is shown by a solid line) to fix the first semi-circular plate a to the base g (Fig. 2a). After that, the first
The second piezoelectric element e is contracted while the second piezoelectric element e is contracted to rotate the second semi-circular plate b by a small angle (FIG. 2b), and in that state, the brake i of the stomach 2 is also activated. To fix the second semi-circular plate b to the base g (Fig. 2c).
Then, the first brake h is released to open the first semi-circular plate a (FIG. 2d), and in that state, both the piezoelectric elements d and e are released.
The first semi-circular plate a is rotated by the same angle as the second semi-circular plate b by returning to the original length (Fig. 2e). Next, the first brake h is actuated to actuate the two semi-circular plates a,
b is fixed, and then the second brake i is released to return to the state of FIG. 2a described above. Then, by repeating this cycle, the rotating body f is moved to the piezoelectric elements d and e.
It can be finely rotated in the counterclockwise direction in the figure by a minute angle corresponding to the amount of expansion and contraction. In addition, the piezoelectric element d,
By reversing the expansion and contraction of e, the rotating body f can be rotated clockwise in the drawing.

With such a structure, a large stroke can be obtained as compared with a case where the piezoelectric element is directly urged to rotate the rotating body, but there is a certain limit. That is, this is a piezoelectric element d, e
Since it is incorporated, it is indispensable to route the lead wire from the base g to the rotating body f, and the rotating body f cannot be endlessly rotated. Also,
Such a structure requires a total of four types of piezoelectric elements, one for urging the semi-disc and the other for braking, and these elements must be operated at different timings. Therefore, not only the structure becomes complicated, but also the circuit for controlling the energization to the piezoelectric element becomes complicated, and the cost of the device cannot be avoided.

(C) Objective The present invention has been made in view of such circumstances.
With a simple structure, it is possible to perform high-precision rotation drive with high precision, and it can be made to perform endless rotation, and since it generates minimal heat and gas emission, it can be widely used in various fields. An object is to provide a rotary drive device.

(D) Configuration In order to achieve such an object, the fine-rotation drive device of the present invention is provided with a first rotating disk rotatable about an axis and a contact surface contacting an outer peripheral surface of the first rotating disk. Of the electrostrictive actuator, a floating fulcrum that supports the electrostrictive actuator so that the abutting surface can tilt while abutting the outer peripheral surface of the rotating disk, and the abutting surface of the electrostrictive actuator is the rotating disk. Elastic biasing means that presses the outer peripheral surface of the first electrostrictive actuator, and a second electrostrictive actuator that tilts the first electrostrictive actuator to move the contact position between the attachment surface and the outer peripheral surface in the circumferential direction. It is characterized by

(E) Embodiment Hereinafter, one embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 3 and 4, a turntable 1 as a rotating disk is rotatably arranged on a base 2. The turntable 1 is a thick disk-shaped outer peripheral surface 1a processed with high precision, and a shaft portion 1b provided at its axial center portion is supported by the base 2 via a bearing 3. As the bearing 3,
It is preferable to use a bearing that does not rattle, such as a magnetic bearing or a hydrostatic bearing. The outer peripheral surface 1a of the turntable 1 is brought into contact with the attachment surface 4a of the first electrostrictive actuator 4. As shown in FIGS. 5 and 6, the first electrostrictive actuator 4 has a plurality of electrostrictive elements 8 stacked and housed in a prismatic case 7 having flanges 5 and 6 at both ends. An adjusting screw 9 is screwed on the end wall of the case 7, and a spacer 11 is interposed between the adjusting screw 9 and the electrostrictive element 8. The first electrostrictive actuator 4 is assembled in such a state that the adjusting screw 9 is tightened with a required torque to slightly distort the electrostrictive element 8, and a voltage is applied to the electrostrictive element 8. Then, the dimension L between A and A'expands and contracts by several microns. Then, the first electrostrictive actuator 4 is supported by a floating fulcrum 12 so that the abutting surface 4a thereof can be tilted while abutting on the outer peripheral surface 1a of the turntable 1. Specifically, the floating fulcrum 12 is an L-shaped fixture 13 fixed to one flange portion 5 of the first electrostrictive actuator 4.
And a support portion 15 of the frame 14 fixed to the base 2 are connected by a leaf spring 16. In addition, the first electrostrictive actuator 4 is attached to the elastic biasing means 1
7 is urged in the direction of the turntable 1 and its supporting surface 4
A is pressed against the outer peripheral surface 1a of the turntable 1. Specifically, the elastic biasing means 17 has a compression coil spring 19 interposed between the frame 14 and the L-shaped fitting 18 fixed to the other end flange portion 6 of the first electrostrictive actuator 4. It is a thing. A release lever 21 is integrally formed at the tip of the fixture 18, and the release lever 21 is operated manually or electrically or in a hydraulic pressure drive direction in a direction against the spring 19 (arrow X direction). By doing so, the attachment surface 4a of the first electrostrictive actuator 4 can be separated from the outer peripheral surface 1a of the turntable 1. Further, the first electrostrictive actuator 4 is tilted by the second electrostrictive actuator 22 to move the contact position with the abutting surface 4a in the circumferential direction. Specifically, the second electrostrictive actuator 22 has the same content structure as the first electrostrictive actuator 4 described above. Then, this second electrostrictive actuator 2
2 has one of the flange portions 23 fixed to the fixture 13 and the other flange portion 24 of the frame 1.
The first electrostrictive actuator 4 and the first electrostrictive actuator 4 are arranged orthogonal to each other while being fixed to the mount portion 25 of No. 4.

Next, the operation of this embodiment will be described.

First, in a state where no voltage is applied to both electrostrictive actuators 4 and 22, the attachment surface 4a of the first electrostrictive actuator 4 and the outer peripheral surface 1a of the turntable 1 are shown in FIGS. 3 and 7a. Thus, they are in contact with each other at the first point P1 (see t0 in FIG. 8). In other words, the first contact portion 26 of the first electrostrictive actuator 4 and the first contact portion 27 of the turntable 1 are in contact with each other. When a voltage is applied to the second electrostrictive actuator 22 from this state to extend the second electrostrictive actuator 22, as shown exaggeratedly in FIG. 3 (imaginary line) and FIG. 7 (b). , The first electrostrictive actuator 4 tilts clockwise in the figure, and the contact position between the attachment surface 4a of the first electrostrictive actuator 4 and the outer peripheral surface 1a of the turntable 1 reaches the second point P2. Moving. In other words, the second contact portion 28 of the first electrostrictive actuator 4 and the second contact portion 29 of the turntable 1 are in contact with each other. Then, after the second electrostrictive actuator 22 is fully extended and the tilt angle of the first electrostrictive actuator 4 is maximized (see t1 in FIG. 8), FIG.
As shown, the voltage is applied to the first electrostrictive actuator 4 to extend the first electrostrictive actuator 4. Thereby, the first contact portion 2 of the first electrostrictive actuator 4 is
The distance between 6 and the second contact portion 28 changes from d to d + Δd. Here, Δd is several microns. In this way, after the first electrostrictive actuator 4 is fully extended (8th
(See t2 in the figure), the voltage application to the second electrostrictive actuator 22 is stopped. As a result, as shown in FIG. 7 (d), the first electrostrictive actuator 4 tilts in the opposite direction to the previous one and returns to the original posture, and the first electrostrictive actuator 4 is attached. The contact position between the contact surface 4a and the outer peripheral surface of the turntable 1 is from the second point P2 to the first point P1.
Return to. However, since the first electrostrictive actuator 4 is in the extended state as described above, the first contact portion 26 does not contact the first contact portion 27 of the turntable 1, but the first contact portion 26. The third contact portion 31 on the right side of the figure by Δd from 26 comes into contact with the first contact portion 27. In this way, the voltage application to the first electrostrictive actuator 4 is stopped when the second electrostrictive actuator 22 is fully restored (see t3 in FIG. 8).
Then, as shown in FIG. 7 (e), the first electrostrictive actuator 4 is reduced to its original length. At this time, the turntable 1 corresponds to Δd in the figure. Can be rotated clockwise. That is, the distance between the first contact portion 26 and the second contact portion 28 is reduced from d + Δd to d, and at this time, the outer circumference of the turntable 1 is rotated by several microns to the right to complete one cycle. By repeating the above operation, the turntable 1 rotates endlessly. The rotation angle per pulse at this time can be adjusted in the range of 0 to several seconds by adjusting the voltage applied to the first electrostrictive actuator 4. When it is desired to reverse the rotation direction, the timings of the voltages applied to the first electrostrictive actuator 4 and the second electrostrictive actuator 22 are reversed as shown in FIG.
It suffices to reverse the polarity of the voltage applied to.

The rotating disc is not limited to the turntable, but may be, for example,
It may be a drive-only disc provided coaxially with the turntable. Moreover, the application is not limited to the one for the exposure apparatus, but also for the sample stage such as an electron microscope and an electron beam analyzer, and for the part for rotating and adjusting the mirrors and prisms of the optical equipment. And so on.

Further, the elastic biasing means is not limited to the one using a spring, but may be one using rubber or fluid pressure, for example.

Further, in the above embodiment, the case where the electrostrictive actuator is attached to one side of the rotating disk has been described, but the present invention is not necessarily limited to this.
An electrostrictive actuator may be attached to both sides of the rotating disk.

The rotation angle per pulse may be adjusted by changing only the voltage applied to the first electrostrictive actuator as described above, but the voltage applied to the first and second electrostrictive actuators may be adjusted. You may make it adjust by changing.

(F) Effects Since the present invention is configured as described above, the following effects can be obtained.

First, the first electrostrictive actuator is always attached to the outer peripheral surface of the rotary disk, and the first electrostrictive actuator is tilted by the second electrostrictive actuator to expand and contract, whereby the rotary disk is finely rotated. Since there is no backlash, fine expansion / contraction control of the electrostrictive element enables highly accurate fine rotation drive. Therefore, it is easy to drive with an angular accuracy of about 0.1 seconds per pulse, and further, by increasing the outer diameter of the rotating disk, a resolution of 0.1 seconds or less can be obtained.

Further, since the rotary disk is driven by using only two kinds of electrostrictive actuators, the structure is simple and the control is easy, and an inexpensive device can be provided.

Moreover, since no electrostrictive element is provided on the rotating disc side, it is not necessary to install a lead wire between the rotating disc and the base. Therefore, endless rotation is possible.

Further, since the electrostrictive actuator emits less gas, it can be installed even in a vacuum, so that a vacuum seal of the drive shaft is unnecessary. Therefore, it is possible to provide an excellent rotation drive device that does not deteriorate the atmosphere in combination with the fact that the temperature does not rise.

Furthermore, if it is such a thing, the brake can be released manually regardless of the voltage control.
Operability can also be improved.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a conventional example, and FIGS. 2 (a), (b), (c),
(d), (e) and (f) are operation explanatory views of the conventional example. FIGS. 3 to 9 show an embodiment of the present invention, FIG. 3 is a plan view showing a main part, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is an electrostrictive actuator. FIG. 6 is a side sectional view showing the same, FIG. 6 is a side view of the same, FIGS. 7 (a), (b), (c), (d), and (e) are explanatory views of action, and FIGS. It is a figure which shows the application timing of a voltage. DESCRIPTION OF SYMBOLS 1 ... Rotating disk (turntable) 1a ... Outer peripheral surface 2 ... Base 4 ... 1st electrostrictive actuator 4a ... Attachment surface 8 ... Electrostrictive element 12 ... Floating Fulcrum 17 ... elastic biasing means 22 ... second electrostrictive actuator P1 ... first point P2 ... second point

Claims (1)

[Claims] 1. A rotary disk rotatable about an axis and a contact surface contacting the outer peripheral surface of the rotary disk. The deformation of an electrostrictive element is utilized to transform the contact surface into the rotary disk. A first electrostrictive actuator configured to expand and contract in the tangential direction of the plate; and a floating fulcrum that supports the electrostrictive actuator so that the abutting surface can tilt while abutting against the outer peripheral surface of the rotating disk. An elastic biasing means for pressing the attachment surface of the electrostrictive actuator against the outer peripheral surface of the rotating disk; and the contact position between the attachment surface and the outer peripheral surface of the first electrostrictive actuator being tilted to the circumference. And a second electrostrictive actuator that moves in a direction.