JPS6215049A - Micro positioning device - Google Patents

Abstract

PURPOSE:To enable quick micro positioning to a desired stroke by adjusting brake releasing time for a substance as held under an actuating force and partially overlapping the brake releasing time through a plurality of braking devices. CONSTITUTION:A piezo element 4 is applied with an electric field for the elongation thereof, and a a friction plate 5 fitted with such an element is pressed against a bar 3, and then exposed to a force 'F' from the left side. This force 'F' is smaller than a friction force between the friction plate 5 and the bar 3, and this bar 3 is at a rest. Then, the piezo element 4 is exposed to an electric field in a reverse direction, or momentarily made to shrink with the removal of the electric field for releasing friction between the friction plate 5 and the bar 3. Thereafter, the piezo element 4 is again exposed to an electric field for elongation and the bar 3 is made still by pressing the friction plate 5 thereto. In this state, time when the bar 3 is offthe friction plate 5, is controlled, thereby enabling the decision of any desired position. Also, it is possible to obtain micro positioning by using a piezo element and an electric magnet, each having high frequency response to time control.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention generally relates to a micro-positioning device, and in particular to a device suitable for micro-positioning of a stage of semiconductor manufacturing equipment or micro-positioning of an optical element in an optical device. This is related to.

[Prior Art] Some conventional micro-positioning devices displace a driven member by utilizing expansion and contraction when an electric field is applied to a piezo element. In other words, one that displaces the driven member by a stroke corresponding to the expansion or contraction of the piezo element when the piezo element is brought into direct contact with the driven member and an electric field is applied;
A piezo element (Fig. 7, 4) that expands and contracts in the axial direction of the driven member is arranged around the driven member (cylindrical moving rod, Fig. 7, 3), and one end of this piezo element grips the driven member, With the other end separated from the driven member (Fig. 7b), an electric field is applied to extend the piezo element in the axial direction of the driven member.
In this stretched state, grasp the driven member with the other end of the piezo element (Fig. 7 d), and then release said end of the piezo element from the driven member (Fig. 7 e). Applying an electric field in the opposite direction causes the piezo element to contract in the axial direction of the driven member (
In this contracted state, grasp the driven member with the one end of the piezo element (7th cause), then release the other end of the piezo element from the driven member (Figure 7 f), and as follows: There is a method in which the driven member is displaced by an arbitrary amount determined by a multiple of the stroke corresponding to the expansion or contraction of the piezo element by repeating this main movement.

The former has a problem in that the amount of displacement is too small, and the latter has the problem that although the amount of displacement can be increased, it takes too much time to make the displacement.

[Problems to be Solved by the Invention and Means for Solving the Problems] An object of the present invention is to solve the above-mentioned problems and provide a micro-positioning device that can quickly and accurately drive a driven member by an arbitrary amount of displacement.

This object, according to the invention, includes a driven member, a power means connected to the driven member and generating power for driving the driven member, a braking means for stopping the movement of said driven member;
and means for adjusting the brake release time of the brake means, thereby displacing the driven member as a function of the brake release time.

In particular, the micro-positioning device of the present invention can be used with air cylinders, oil cylinders, or springs depending on the required accuracy.

Any power means such as electromagnets, linear motors, weights, etc. can be used, and positioning can be performed with any resolution.

Further, it is possible to take a large amount of displacement, and in that case, it is possible to move at high speed.

Furthermore, since the stop is caused by frictional force, minute vibrations in the positioning direction are not generated.

Embodiment FIG. 1 is a perspective view of an embodiment of the micro-positioning device of the present invention, with a part of the case cut away to show the internal structure.
FIG. 2 is a longitudinal sectional view thereof.

In Figure 1, 1 is a case, 2.2' is a ball pusher that is a linear guide, 3 is a bar that is a driven material, 4 is a piezo element that performs braking, and 5 is a piezo element with a large friction coefficient and excellent wear resistance. The friction plate 6 is a cylinder serving as a driving force source.

The operation will be explained with reference to FIG. An electric field is applied to the piezo element 4 to stretch it and push the friction plate 5 attached to it against the bar 3, and in this state a force F is applied from the left side. Since the force F applied at this time is weaker than the FJ frictional force between the friction plate 5 and the bar 3, the bar 3 remains stationary. Next, apply an electric field to the piezo element 4 in the opposite direction, or remove the electric field to momentarily contract the piezo element to eliminate friction between the FJyA plate 5 and the bar 3, and then apply an electric field to the piezo element 4 again. Stretch this out to FJ15! The plate 5 is pressed against the bar 3 to make the bar 3 stationary. The distance X that the bar 3 moved during this brake release period is the mass M1 of the bar, and if the time during which the friction plate 5 and the bar 3 were separated is t, then the distance X is determined by the following equation.

x -1/2-F/M-t2 Therefore, arbitrary positioning is possible by controlling the time t during which the bar 3 is separated from the S swing plate 5. Further, by using a piezo element or an electromagnet with high frequency response to control the time t, minute positioning is also possible.

In this embodiment, a ball push is used, but a highly accurate linear guide element using a pressure bearing or a magnetic bearing may be used instead.

Figure 3 shows a modification of the first embodiment, with a piezo element 4a for braking.
, 4b and two sets of friction plates 5a, 5b are arranged in parallel. In this modification mode, displacement over a minute distance is performed by controlling a time shorter than the response speed of the piezo element.

As shown in FIG. 4, there is a brake release operation in which the piezo element 4a is momentarily retracted to separate the friction plate 5a from the bar 3, and a brake release operation in which the piezo element 4b is momentarily retracted and the friction plate 5b is separated from the bar 3. By shifting the timing of , the time t2 in which the bar 3 is not braked can be made shorter than the brake release time t1 by a single piezo element.

FIG. 5 shows an embodiment of a rotary micro-positioning device. Fifth
In the figure, 3 is a rotating disk, 4.4' is a piezo element for applying braking to the rotating disk 3, 5 is a friction plate attached to the piezo element, 6 is a cylinder that provides driving force, 8 is a ball bearing, and 9 is a cylinder. A connecting rod is connected to the piston, and 10 is a joint that transmits moment force to the rotating disk 3.

In operation, after fixing the disk 3 by stretching the piezo element 4 , 4 ′ in the thickness direction of the disk 3 , pressure is applied to the cylinder 6 and force is applied to the joint 10 through the connecting rod 9 . At this time,
The disk 3 attempts to rotate around the ball bearing 8, but remains stationary because the braking force of the piezo element is greater.

Next, the piezo elements 4, 4' are momentarily contracted, the circle W3 is released from the braking state, and the piezo elements 4, 4' are extended again.
Put disk 3 in υ1 motion state. During this brake release period, disk 3
The rotation angle θ is the torque by the cylinder 6 T1
If the moment of inertia of the disk is I, it is expressed as θ-1/2·T/I-t'. Therefore, by adjusting the brake release time of the disk 3, positioning at any rotation angle can be performed.

Also, as shown in FIG. 6, there are two sets of braking piezo elements 4a.

By arranging 4'a: 4b and 4'b in the direction of movement of the disk 3 and adjusting the braking release times so that they partially overlap, positioning at a minute angle can be performed in accordance with this short overlapping time.

The ball bearing 8 of the embodiment of FIGS. 6 and 7 can also be a high-precision bearing, such as a hydrostatic bearing or a magnetic bearing.

[Effects of the Invention] As explained above, by adjusting the braking release time of an object that is being braked while a driving force is applied, positioning can be quickly performed with a stroke of a desired size, and multiple objects can be positioned with a stroke of a desired size. Even finer positioning can be achieved by partially overlapping the braking release times of the braking devices. Further, according to the present invention, not only the positioning in the straight direction but also the positioning in the rotational angle can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a first embodiment of the invention. FIG. 2 is a longitudinal sectional view of the first embodiment. FIG. 3 is a longitudinal sectional view of a second embodiment of the invention. FIG. 4 is a graph explaining the operation of the second embodiment. FIG. 5 is a perspective view of a third embodiment of the invention. FIG. 6 is a perspective view of a fourth embodiment of the invention. FIGS. 7a to 7h are explanatory diagrams of the operation of the inchworm mechanism of the conventional micro-positioning device. In the figure: 1: case, 2-ball bush, 3: driven member, 4: piezo element, 5: friction plate, 6: driving force source, 8: ball bearing, 9: connecting rod, 10: joint.

Claims (1)

[Claims] 1. A driven member; A power means connected to the driven member and generating power for driving the driven member; A braking means for stopping the movement of the driven member; and this braking means A micro-positioning device comprising: means for adjusting a brake release time of the brake, thereby displacing a driven member as a function of the brake release time. 2. The micro-positioning device according to claim 1, wherein the driven member is a bar supported by a ball pusher, a hydrostatic bearing, or a magnetic bearing. 3. The micro-positioning device according to claim 1, wherein the driven member is a disk supported by a ball bearing, a hydrostatic bearing, or a magnetic bearing. 4. The micro-positioning device according to claim 1, 2 or 3, wherein the braking means is at least one piezo element having a friction plate fixed facing the driven member. 5. The micro-positioning device according to claim 1, 2 or 3, wherein the braking means is at least one electromagnet having a friction plate fixed facing the driven member. 6. The micro-positioning device according to claim 4, wherein two or more of the piezo elements are sequentially arranged in the driving direction of the driven member. 7. The micro-positioning device according to claim 5, wherein two or more of the electromagnets are sequentially arranged in the driving direction of the driven member.