JPS61182113A - Minute displacement driver - Google Patents

Abstract

PURPOSE:To attain minute displacement in the lengthwise direction of a shaft with high accuracy by using the piezoelectric means which can be expanded and contracted in the lengthwise direction of the shaft and a set of piezoelectric means which are fixed to a frame so that they can hold and release the shaft. CONSTITUTION:The piezoelectric means 2A and 2B which can be expanded and contracted in the lengthwise direction of a shaft 1 are fixed adherently at the center of the shaft 1 that pierces through a frame consisting of end plates 3A and 3B and bases 4A and 4B. The shaft 1 is held by the frame by means of the piezoelectric means 5 and 6 consisting of piezoelectric elements 5a, 5b, 6a and 6b and adaptors 5c, 5d, 6c and 6d respectively. The holding release action of the single side of the shaft 1 owing to the the functions of means 5 and 6 and the expanding/contracting actions doen by the function of the means 2 in the lengthwise direction of the shaft 1 are repeated alternately. Thus the shaft 1 has displacement in its lengthwise direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a minute displacement drive device, and more particularly to a minute displacement drive device required in fields that require precision in positioning, for example, in the manufacturing process of semiconductor devices.

(Technical Background of the Invention) Accurately performing minute displacements such as minute positioning is
For example, it is required when working on semiconductor wafers or pellets, and in recent years, higher precision has been required.

However, in conventional devices of this kind, a desired displacement is achieved by rotating a threaded shaft by a specified angle using a servo motor, a step motor, or the like.

In this case, when the amount of displacement is less than 1 micron, the mechanical accuracy of the motor components is affected and the accuracy is significantly degraded. In other words, even though the minimum rotation angle of the motor shaft can be calculated to be small by adjusting the thread cutting method, when the amount of displacement approaches the above-mentioned value, so-called bala crash has a large effect, further deteriorating the accuracy.

(Object of the Invention) The present invention has been made in an attempt to eliminate the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a minute displacement drive device that can accurately achieve minute displacements.

(Summary of the Invention) To achieve this object, the present invention provides a shaft for driving a load, and a first shaft that is fixed along the longitudinal direction of the shaft and is expandable and retractable along the longitudinal direction. holding the shaft on both sides of the first piezoelectric means in the direction of extension from a direction substantially perpendicular to the direction of extension;
a set of second piezoelectric means that can be released and fixed to the frame, and positive and negative voltages are sequentially applied to the first piezoelectric means and the set of second piezoelectric means with a time difference, respectively. By doing so, the shaft can be displaced in any left or right direction.

(Example of the invention) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 and 2 show an embodiment of the present invention, and show a side view and a longitudinal cross-sectional view of a micro-displacement drive device, respectively.

The minute displacement drive device of this embodiment includes a shaft 1, first piezoelectric means 2A, 2B, an end play of a frame, ) 3A
, 3B, side plate 3C, 3D, base 4A, 4B,
and second piezoelectric means 5, 6.

The shaft 1 is for driving a load and has a rectangular cross section, and piezoelectric means 2A and 2B are adhesively fixed to the surfaces of the two opposing surfaces at approximately the center in the longitudinal direction. The two piezoelectric means 2A and 2B are rectangular plates,
It is a piezoelectric transverse effect d31 mode element that can be expanded and contracted in the longitudinal direction of the shaft 1 by applying a voltage.

Since the shaft 1 is fixed integrally with the piezoelectric means 2A and 2B, it can expand and contract on the order of several microns by expanding and contracting the piezoelectric means 2A and 2B. At this time, it is desirable that the thermal expansion or contraction of the shaft 1 be the same as that of the piezoelectric means.

Note that the shaft 1 for driving the load may have a circular cross section. Furthermore, the piezoelectric means 2A, 2B may be embedded within the thickness of the shaft 1 so that its surface is flush with the surface of the shaft 1. Furthermore, as shown in FIG. 3, the shaft is divided into two parts 30A.

Divided into 30B, the divided shafts 30A, 30B
may be connected by two opposing piezoelectric means 31A, 31B with a space 32 between them.

In addition, as another method of obtaining the same effect as the first piezoelectric means 2A, 2B, it is possible to obtain exactly the same result by using the piezoelectric longitudinal effect mode d33 or the thickness shear mode d15.

As is almost clear from the foregoing, such a shaft 1 and piezoelectric means 2A, 2B are mounted within a frame consisting of end plates 3A, 3B, side plates 3C, 3D, and bases 4A, 4B.

Also provided within this frame are a set of second piezoelectric means 5.6, each on each side of the shaft 1, which prevents the shaft 1 from moving in the initial state (for example, when no voltage is applied). is holding.

The piezoelectric means 5.6 each include a pair of piezoelectric units, each unit having a piezoelectric element 5a, 5b.

5a, 5b and adapters 5C, 5d, 6C, 6d, respectively. Piezoelectric elements 5a, 5b, 6a.

6b is displaced either in the direction of clamping the shaft 1 or in the direction of releasing this displacement, depending on the polarity of the applied voltage. These piezoelectric elements 5a, 5b, 6a.

One surface of 6b is fixed to bases 4A and 4B.

The adapters 5c, 5d, 5c, and 5a are used to insulate the piezoelectric unit and the shaft, to prevent wear, and to ensure that the piezoelectric unit can grip the shaft 1 without slipping.
, 5a, 6b are glued to one side facing the shaft 1.

Next, the operation of this embodiment will be explained with reference to FIG.

4(a), (b), and (C) show the piezoelectric means 5, 6, respectively.
2 shows the state of the voltage applied to 2. in this case,
The piezoelectric means 5, 6 clamp the shaft 1 with a voltage of positive polarity, release this with a voltage of negative polarity, and the piezoelectric means 2A,
2B is extended by applying a voltage of positive polarity to extend the shaft 1, and contracted by applying a voltage of negative polarity.

At time T1, the voltage applied to any piezoelectric element is positive, but at time T2, the voltage polarity of the piezoelectric means 5 is reversed to negative (
Figure 4(a)). The piezoelectric means 5 therefore unclamp the shaft 1.

At time T3, only the polarities of the voltages applied to the piezoelectric means 2A and 2B are reversed (FIG. 4(C)), and the shaft 1 contracts, which continues until time T5. At this time, since the shaft 1 is in a clamped state by the piezoelectric means 6, the shaft portion on the piezoelectric means 5 side contracts and moves toward the piezoelectric means 6 side. At time T4, the voltage polarity of the piezoelectric means 5 is reversed to positive polarity, so both ends of the shaft 1 are clamped.

Thereafter, the piezoelectric means 6 becomes negative in polarity at time T5, so that the clamped state is released. At time T6, shaft 1
Piezoelectric means 2A to extend.

A positive voltage is applied to 2B, causing the shaft 1 to extend.

For this reason, the shaft l, which had been contracted, is now clamped by the piezoelectric means 5 on the left end and held in the state of IJ, - by the piezoelectric means 6, so it now extends toward the piezoelectric means 6 on the right end, that is, to the right. Displace. At time T7, the piezoelectric means 6 becomes positive and clamps, completing one cycle of operation.

By sequentially repeating the above-mentioned operations, the shaft 1 is displaced toward the piezoelectric means 6, and the displacement speed in this case is determined by the magnitude of the value on the vertical axis of the drive voltage applied to the piezoelectric means 2. , also determined by the speed of the repetition pitch.

Moreover, when the shaft 1 is to be displaced in the opposite direction, that is, toward the piezoelectric means 5 side, the above-mentioned clamping, releasing, and feeding operations can be reversed, and the bird can be controlled by a single signal.

Note that the operating direction of all piezoelectric means is the direction of polarization,
It is determined by a combination with the polarity of the applied voltage, and can be arbitrarily set depending on the purpose.

As can be seen from the above explanation, the movement of the shaft 1 is entirely digital behavior, and the maximum speed is determined by the mechanical resonance of this system, and is usually set at about 5 to 10 kHz.

Therefore, for example, assuming that the amount of displacement per time is 1 μm, this is 1k.
When operating at Hz pitch, a displacement of 1HJ Sec can be obtained.

(Effect of the invention) According to this invention, by configuring as described above,
It is possible to provide a micro-displacement drive device that can accurately achieve micro-displacement.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of the invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a partial sectional view of a modification of one element in FIG. FIG. 4 is an applied voltage waveform diagram for explaining the operation of the embodiment of the present invention. ■... Nyahu [..., 2A, 2B... first piezoelectric means,
3A, 3B, 3C, 3D, 4A, 4B... frame components, 5, 6... second piezoelectric means.

Claims (1)

[Claims] a shaft for driving a load; a first piezoelectric means fixed along the longitudinal direction of the shaft and extendable and retractable along the longitudinal direction; a set of second piezoelectric means fixed to a frame so as to be able to clamp and release from a direction substantially perpendicular to the stretching direction, the first piezoelectric means and the set of second piezoelectric means A micro-displacement drive device that displaces the shaft in any left or right direction by sequentially applying positive and negative voltages with a time difference between the two.