JPH0743430B2 - Fine feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is incorporated in, for example, a semiconductor manufacturing apparatus to finely feed a wafer stage side in a linear direction, or to position a mirror holder in an optical device. The present invention relates to a fine feeding device for performing ultrafine positioning.

[Prior Art] As a conventional fine feed device, there is one in which a linear motor whose drive source is a piezoelectric element is used, and the fine feed is performed by operating the piezoelectric element and extracting the extension force in a straight direction. The device is known.

Further, there is known a fine feed device having a structure in which a step motor is connected to an input rotary shaft of a micrometer head for converting a rotary movement into a straight movement, and a fine straight feed is obtained by finely rotating the step motor. There is.

Further, there is known a fine feed device in which a piezoelectric motor whose rotary drive source is a piezoelectric element is connected to an input shaft of a micrometer head.

[Problems to be Solved by the Invention] In a fine feed device using a linear motor whose drive source is a piezoelectric element, when the drive source is operated for only one step, which is the minimum operation unit, the moving member moves several tens of nm to several μm. Only fine feed. However, in the fine feed of the wafer stage of the semiconductor manufacturing equipment, the minimum feed distance is required to be about 10 to 20 nm, and the fine feed device using the piezoelectric linear motor cannot obtain sufficiently fine feed. was there.

Further, in the fine feed device which is a combination of the micrometer head and the step motor, the step motor can increase the number of steps per one rotation. However, if the number of steps is increased, it becomes difficult to control the voltage application, and as a result, the minimum distance for straight feed is 50 nm at most.
There was a problem that you could only get a degree.

Further, in a fine feed device including a combination of a micrometer head and a piezoelectric motor, examples of the piezoelectric motor include those disclosed in JP-A-63-39477 and JP-A-61-224886. The piezoelectric motor disclosed in Japanese Unexamined Patent Publication No. 63-39477 has a problem in that it has eight piezoelectric elements, the cost is high, and control of voltage application to the piezoelectric elements is complicated. Further, since the stator and the mover have a circular peripheral surface, there is a problem that manufacture is difficult.

On the other hand, the piezoelectric motor disclosed in Japanese Unexamined Patent Publication No. 61-224886 has a problem that it is difficult to manufacture due to the complicated shape of the housing, and the number of members is large and the manufacturing and assembling are complicated.

The present invention has been made in view of the above circumstances, it is possible to feed a sufficiently fine distance, the feeding control is not complicated, and the number of used members is small, and the manufacturing of the member The present invention provides a fine feeding device which is simple and can therefore reduce the cost.

[Means for Solving the Problem] According to the present invention, the amount of displacement given to the rotating body by bringing the specified portion of the rotating body into contact with the inner circumferential surface of the cylindrical body and causing the piezoelectric element to expand It is a fine feed device that performs fine feed by converting a fine rotational moment into a linear feed.

The detailed configuration includes a tubular body having an inner side surface of a circular shape, a rotary shaft portion having an axis line in common with an axis line of the tubular body, and an abutting portion abutting on an inner circumferential surface of the tubular body. A rotating body having
A piezoelectric element disposed and fixed to the rotating body in a direction in which the extending direction of the rotating body with respect to the direction of the rotating shaft is substantially orthogonal to the rotating body, and the piezoelectric element is provided adjacent to the piezoelectric element to extend the piezoelectric element. An inertial body for changing into a rotational driving force, a voltage applying means for applying a desired voltage to the piezoelectric element, and a converting means for connecting a rotary shaft portion of the rotary body and converting a rotational movement into a linear movement are provided. It is a fine feeding device.

Incidentally, as for the case where the so-called play generated between the abutting portion of the rotating body and the inner circumferential surface of the cylindrical body is absorbed, or the processing accuracy of the inner circumferential surface of the cylindrical body is insufficient, the rotating body is There is a fine feed device configured to have a means for adjusting the pressing force of the contact part on the inner circumference of the cylinder between the rotating body and the contact part, and a spring is a specific example of the means. Is mentioned.

Also, for ensuring the smoothness of rotation of the rotating body,
There is a fine feed device in which the abutting member of the rotating body is a rotating member supported on the rotating body main body side.

[Operation] When the piezoelectric element is operated for tens of thousands of steps, the rotating body makes one rotation relative to the cylindrical body.

The control of the operation is only the control of the voltage application to the used piezoelectric element.

The fine feeding device is composed of a cylindrical body whose inner surface is circular, a rotating body, a piezoelectric element, an inertial body, a voltage applying means, and a means for converting rotational movement into linear movement.

Embodiments The present invention will be described in detail based on the embodiments shown in FIGS. However, the present invention is not limited to the embodiments.

As shown in FIGS. 1 to 3, the fine feeding device 1 includes a cylindrical body 2,
It comprises a rotating body 3, piezoelectric elements 4 and 5, inertial bodies 6 and 7, a voltage applying means 8 and a converting means 9.

The cylindrical body 2 is provided with a smooth inner circumferential surface 10, and
The rear part is closed by a flat wall 11. The wall 11 holds the shape of the cylindrical body 2 while inserting and fixing the conversion means 9 therein.

The rotary body 3 includes a rotary body 12, a rotary shaft portion 13, and a contact portion 14 that contacts the inner circumferential surface 10 of the tubular body 2. When the rotating body 3 is arranged at a predetermined position with respect to the tubular body 2 so that the contact portion 14 contacts the inner circumferential surface 10, the axis of the rotating shaft portion 13 coincides with the axis of the inner circumferential surface 10. Is formed.

The contact portion 14 is specifically a rotating member supported by a bearing (not shown). Also, the rotating body 12 and the contact portion
Between the rotating member 14 and the rotating member 14, there is provided a means 15 for adjusting the force of contacting and pressing the inner circumferential surface 10 of the contact portion 14. That is, the recess 16 is formed in the rotary body 12, and the support 17 that supports the contact portion 14 is fitted in the recess 16.
Further, a coil spring 18 is arranged between the recess 16 and the support 17. Reference numeral 19 denotes a screw that is screwed into the rotating body body 12 to prevent the support body 17 from rotating with respect to the rotating body body 12.

The piezoelectric elements 4 and 5 are the rotating body 3 and include the rotating shaft portion 13 and the contact portion 1
It is arranged and fixed at a site forming a triangle together with 4, that is, a site deviated from the line connecting the rotating shaft part 13 and the contact part 14. The extension directions of the piezoelectric elements 4 and 5 are determined so as to extend in a direction orthogonal to the direction toward the rotary shaft portion 13 from the disposed portion. The piezoelectric elements 4 and 5 expand (displace) with respect to the applied voltage as shown in FIG.

The inertial bodies 6 and 7 are for giving a rotation moment to the rotating body 3 when the piezoelectric elements 4 and 5 perform extension action, respectively.

The voltage applying means 8 is between 15V and 85V as shown in FIG.
The voltage is applied to the piezoelectric elements 4 and 5 so that the movements are opposite to each other between the minimum applied voltage and the maximum applied voltage. The front surface of the voltage applying means 8 is an operation panel 23 having counters 21 and 22. Operator on the operation panel
It is possible to operate the piezoelectric elements 4 and 5 from 23 with a desired number of extension operations. The counter 21 counts and displays the number of times the piezoelectric elements 4, 5 are extended. The counter 22 is for displaying the straight movement distance of the output member 20 based on the count number of the counter 21.

The conversion means 9 receives the rotational movement (direction of arrow A) of the rotating body 3 from the rotary shaft portion 13 and converts it into straight movement (direction of arrow B). The conversion means 9 is specifically a linear-acting micrometer head, and converts the rotational movement of one rotation into a linear movement of 0.5 mm.

The fine feeding device 1 is configured as described above. The operation of the fine feeding device 1 will be described below.

By operating the voltage applying means 8, as shown in FIG. 5, the voltages applied to the piezoelectric elements 4 and 5 are opposite to each other in the change of the applied voltage between 15 and 85V. The piezoelectric element 4 which has received this voltage application is initially from point C to D shown in FIG.
Up to the distance up to, and due to this rapid expansion, a repulsive force in the direction of arrow E is generated between the inertial body 6 and the rotating body 3. Of these repulsive forces, the repulsive force acting on the rotating body 3 becomes a rotational driving force and rotates the rotating body 3 in the direction of arrow A only slightly.

Then, when the extension of the piezoelectric element 4 is slowly released by the distance from the point D to the point F shown in FIG.
Is in contact with the inner circumferential surface 10 of the cylindrical body 2 and frictional force acts,
The rotating body 3 holds the same position with respect to the cylindrical body 2.

Further, when the release of the expansion of the piezoelectric element 4 is suddenly stopped at the point F, the same force as when the inertial body 6 collides with the rotating body 3 via the piezoelectric element 4 acts on the rotating body 3, and this force rotates. The body 3 is rotated in the direction of the arrow A only slightly more.

On the other hand, regarding the piezoelectric element 5, the inertial body 7 and the rotating body 3,
At the mounting portion of the piezoelectric element 5 of the rotating body 3, a force having the same size as the piezoelectric element 4 but in the opposite direction acts.
Since the force acting on the rotating body 3 by the piezoelectric element 5 is symmetrical with respect to the portion of the rotating body 3 acting on the rotating body 3 by the piezoelectric element 4 with respect to the rotation shaft portion 13, it acts on the rotating body 3 by the piezoelectric element 4. It is exactly the same as the power to do.

That is, the piezoelectric elements 4 and 5 simultaneously apply to the rotating body 3 a rotating force having the same size and the same rotating direction as the rotating body 3. Then, when the rotator 3 is rotated by the expansion of the piezoelectric elements 4 and 5, the rotational movement force is transmitted from the rotary shaft portion 13 to the conversion means 9.

The converting means 9 receives the input from the rotary shaft portion 13 and moves the output member 20 in a straight line in the arrow B direction.

On the other hand, when voltages opposite to the above are applied to the piezoelectric elements 4 and 5, respectively, the rotating body 3 consequently rotates in the direction opposite to the arrow A direction, and the output member 20 moves in the direction opposite to the arrow B direction. Go straight for the same distance. That is, the fine feeding device 1
Is capable of fine feed in both forward and reverse directions.

Here, assuming that one cycle of the extension operation of the piezoelectric elements 4 and 5 is one step, the rotary element 3 rotates once by the extension operation of the piezoelectric elements 4 and 5 of about 50,000 steps. That is, the output members 20 are moved straight by 0.5 mm by performing the expansion operation of the piezoelectric elements 4 and 5 for about 50,000 steps. Then, since the piezoelectric elements 4 and 5 can be controlled at a minimum step by step, the rotation of the rotating body 3 is about 5 which corresponds to one step of the piezoelectric elements 4 and 5.
One-millionth rotation can be controlled, and further, the linear movement distance of the output member 20 corresponds to about one-50,000th rotation of the rotating body 3.
10nm can be controlled.

The fine feed device 1 only needs to control the voltage application to the two piezoelectric elements 4 and 5, and does not need a complicated controller. Further, the fine feeding device has a cylindrical body 2, a rotating body 3, piezoelectric elements 4,5, inertial bodies 6 and 7, a voltage applying means 8 and a converting means 9 as the constituent members, and the number of parts is small, and further, the manufacturing is performed. No complicated member is required. Therefore, the fine feed device 1 can reduce the cost. In particular, the above-described fine feed device 1 uses the two piezoelectric elements 4 and 5 in order to obtain a larger rotational driving force, but the present invention may use only one piezoelectric element. Therefore, according to the present invention, it is possible to simplify the control of the voltage application of the piezoelectric element to be used and further reduce the number of parts to be used, and it is possible to further reduce the cost.

Further, the fine feeding device 1 is provided with means 15 for adjusting the pressing force of the contact portion 14 on the inner circumferential surface 10 between the rotor body 12 and the contact portion 14 of the rotor 3. With the above, it is possible to adjust the pressing force, absorb backlash generated between the abutting portion 14 and the inner circumferential surface 10, and even if the working accuracy of the inner circumferential surface 10 is insufficient, The expansion operation of the piezoelectric elements 4 and 5 can be surely converted into the rotational force of the rotating body 3, which allows the rotating body 3 to rotate uniformly.

In addition, since the contact portion 14 of the rotating body 3 is the rotating member supported by the bearing in the fine feed device 1, the rotating body 3 contacts the cylindrical body 2 in cooperation with the adjusting means 15 described above. While the rotation is smoother.

In the fine feed device 1, the piezoelectric elements 4 and 5 have the same output magnitude, but the output timings may be the same, and the output magnitudes need not be the same.
Further, the present invention may be configured such that one piezoelectric element is used as described above when the rotational driving force of the rotating body 3 may be small, and when a large rotational driving force is desired, A configuration using three or more piezoelectric elements can also be used.

In the fine feed device 1, the conversion means 9 is a direct acting type micrometer head, but it may be a rolling type micrometer head in which the output member is rotated along with the rectilinear movement.

By combining the fine feed device 1 with the coarse movement feed device, a feed device having a long feed distance can be configured.

The fine feeding device 1 can constitute an automatic feeding device together with a means for detecting the feeding distance.

EFFECTS OF THE INVENTION The present invention has a sufficiently fine feed distance, is easy to control the device, has a small number of parts to be used, and is easy to manufacture each member. It is a fine feed device that can reduce costs.

Further, the present invention can include means for adjusting the pressing force of the rotating body that abuts on the inner circumferential surface of the cylindrical body, and by providing the means, it is possible to absorb backlash generated between the rotating body and the cylindrical body, It is possible to eliminate the unevenness of the rotation driving force that occurs when the machining accuracy of the cylindrical inner circumferential surface is low.

Further, in the present invention, the member that abuts on the cylindrical body of the rotating body can be configured as a rotating member, and this configuration can make the rotation of the rotating body smoother.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a front view of the embodiment with some omissions and some notches, and FIG. 3 is a second I-I sectional view. FIG. 4 is a characteristic explanatory view showing the characteristic of the piezoelectric element used in this embodiment, FIG. 5 is a relational explanatory view showing the relationship between the voltage applied to the piezoelectric element of this embodiment and time, and FIG. It is a relationship explanatory view which shows the relationship between the displacement amount of an example piezoelectric element, and time. 1 ... Fine feed device, 2 ... Cylindrical body, 3 ... Rotating body, 4,5
...... Piezoelectric element, 6,7 ...... Inertial body, 8 ...... Voltage applying means,
9 ... conversion means, 10 ... inner circumferential surface, 13 ... rotating shaft part,
14 ... Contact part, 20 ... Output member.

Claims (3)

[Claims] 1. A cylindrical body having an inner surface of a circular shape, a rotary shaft portion having an axis line common to the axial line of the cylindrical body, and an abutting portion abutting on an inner circumferential surface of the cylindrical body. A rotating body, a piezoelectric element disposed and fixed to the rotating body in a direction in which the extending direction of the rotating body with respect to the direction of the rotating shaft is substantially orthogonal to the rotating body, and the piezoelectric element provided adjacent to the piezoelectric element and extending the piezoelectric element. An inertial body for changing the rotational driving force of the rotating body, a voltage applying means for applying a desired voltage to the piezoelectric element, and a rotating shaft part of the rotating body, and a converting means for converting a rotational movement into a linear movement. A fine feeding device provided with. 2. The device according to claim 1, further comprising means for adjusting a pressing force of the contact portion against the inner circumferential surface of the cylindrical body between the rotation body and the contact portion of the rotating body. Fine feed device. 3. The fine feed device according to claim 1, wherein the contact portion of the rotating body is a rotating member supported on the rotating body main body side.