JPH02241373A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To alleviate working and assembling accuracies by holding a movable member between a stationary wall member and a movable wall member. CONSTITUTION:A piezoelectric actuator is composed of stationary wall members 2-3, a movable wall member 4, a movable member 5, two side plates 8, etc. Screws are used as clamping means 9 to be movable to the member 4 by adjusting it. The member 5 is composed of two clamp elements 6a-6b, a linear driving element 7, and a movable rod 10. As a result, when the clamping degree of the screw 9 is controlled, the influence of an external vibration can be reduced.

Description

[Detailed Description of the Invention] [Summary] With regard to piezoelectric actuators, the purpose is to eliminate the need for ultra-precise processing and assembly accuracy on the order of μm or less. a fixed wall member, a movable wall member supported so as to be able to move in parallel in a gap between the fixed wall members by a plurality of fastening means protruding from the wall surface of the fixed wall member, and two movable wall members made of a piezoelectric material. A movable member having a clamp element and a linear drive element fixed in an H shape, and a movable rod fixed to the clamp element, the movable rod passing through the side plate and clamping the movable member. The element is configured to be sandwiched between the fixed wall member and the movable wall member by the tightening means.

[Industrial application field]

The present invention relates to piezoelectric actuators.

In recent years, with advances in manufacturing technology centered on semiconductor integrated circuit devices, for example, in exposure apparatuses used for fine patterning, actuators with a positioning accuracy of 0.1 μm and a movement range of 10 cm are required.

Furthermore, in a scanning tunneling microscope that can observe the arrangement of atoms in real space, actuators with even higher positioning accuracy on the nanometer scale are required.

It is desired to develop a high-precision positioning actuator that has performance that meets these demands, has a simple structure, and does not require strict precision during processing and assembly.

[Conventional technology]

Conventional actuators used for ultra-high precision positioning include a piezoelectric actuator that uses a fixed mechanism such as an electrostatic adsorption clamp or a piezoelectric clamp, and a piezoelectric actuator that uses a lever or a spring. There are mechanical actuators that use screws to scale up and down the movement of a micrometer, and magnetic actuators that use Lorentz force and consist of a permanent magnet and coil.

In any case, each type of actuator has its advantages and disadvantages, and there is a desire for an actuator that has a simple mechanism and operates at high speed and stability.

Among them, piezoelectric actuators are currently widely used, and further development is expected.

FIG. 2 is an explanatory diagram of a conventional piezoelectric actuator, in which (A) is a perspective view of the actuator, and (B) is an explanatory diagram of the operating procedure.

In the figure (A), the piezoelectric actuator 1 has a structure in which an H-shaped movable member 5 is sandwiched between two fixed wall members 2.3.

Here, the movable member 5 includes a pair of parallel clamp elements 6a.
, 6b, and a linear drive element 7 that connects both of them in an H-shape.

The two clamp elements 6a and 6b are each
In the extended state, it is firmly held in the gap between the fixed wall members 2.3 and does not move, and in the contracted state, a gap is created between the fixed wall members 2.3 and it can move freely.

Therefore, as shown in Figure CB), (a) the clamp element 6b is held between the fixed wall members 2.3, and the clamp element 6a is contracted to move freely; (b) linear drive. The clamp element 6a is moved forward by extending the element 7, (c) the clamp element 6a is extended and clamped by the fixing member 2.3, (d) the clamp element 6b is contracted so that it can move freely; ) The linear drive element 7 is contracted to move the clamp element 6b forward in the direction of the clamp element 6a, (f) the clamp element 6b is extended and clamped by the fixing member 2.3, (g) the first (b) return.

By repeating this series of Shakutori Domo movements,
The movable member 5 can move forward through the gap between the fixed wall members 2 and 3.

You can also move backwards by repeating the reverse of this action.

The linear drive element 7 made of a piezoelectric material depends on the material of the piezoelectric material and whether it is a single structure or a laminated type, but for example, it has a prismatic shape with a length of 10 mm, and the applied pulse voltage is ±
When it is 10 cm, it expands or contracts by about 1 μm in the longitudinal direction.

Therefore, for example, if a DC pulse is applied 1000 times in 10 minutes and the shakutori-do-like action is repeated, approximately 1ml11
movement is possible.

Since the clamp elements 6a and 6b are also made of the same piezoelectric material, they have the same electrical and mechanical performance.

Generally, the length of the clamping elements 6a, 6b is 20 to 30I.
Since it is about III11, it is necessary to be firmly held in the gap between the fixed wall members 2.3 and to be able to move freely by expansion and contraction of several micrometers.

That is, the length of the clamp elements 6a, 6b and the fixing member 2
．． Very strict precision is required for dimensions such as the gap in No. 3.

[Problem to be solved by the invention]

As mentioned above, there are various types of actuators that can be used for ultra-high precision positioning.Among these, piezoelectric actuators, which have been widely used in the past and have been the mainstay for measuring length, are used to form the movable member. For example, when a multilayer piezoelectric element is used as a prismatic piezoelectric element with a length of 10 mm, the amount of expansion and contraction is very small, about ±1 μm when a pulse voltage of ±IOV is applied.

Therefore, in order to construct an actuator, the piezoelectric element and the fixed wall member that supports the piezoelectric element must be precisely machined with a high precision of micrometers or less.

That is, specifically, first, the two clamp elements are
Each length must be the same with an accuracy of 1 μm or less.

Next, both end surfaces of the two clamp elements that come into contact with the fixed wall member must have the same flatness and parallelism with an accuracy of 1 μm or less.

Further, the wall surfaces of the two fixed wall members that sandwich the clamp element must also have the same flatness and parallelism with an accuracy of 1 μm or less.

Furthermore, the relationship between the length of the two clamp elements and the distance between the two fixed wall members that sandwich the clamp elements is 1μ.
Must be identical with an accuracy of m or less.

As described above, conventional piezoelectric actuators have had many difficult problems in terms of processing and assembly accuracy.

[Means to solve the problem]

The problem described above is that the gap between the fixed wall members is narrowed by the two opposing fixed wall members fixed to the two opposing side plates and the plurality of tightening means protruding from the wall surface of the fixed wall members. a movable wall member supported so as to be able to move in parallel; a movable member having two clamp elements made of piezoelectric material and a linear drive element fixed in an H shape; and a movable rod fixed to the clamp element. and a piezoelectric actuator configured such that the movable rod passes through the side plate and the clamp element of the movable member is held between the fixed wall member and the movable wall member by a tightening means. .

[For production]

In the piezoelectric actuator 1 according to the present invention, a movable wall member is provided in a gap between two opposing fixed wall members, and is supported so as to be able to move in parallel by a tightening means 9 protruding from each fixed wall member. The coarse movement member is sandwiched and held between the fixed wall member and the movable wall member, which is a feature of the present invention.

In other words, among the several required machining and assembly precisions, the flatness and parallelism of the two clamp elements of the movable member,
The flatness of the fixed wall member and the movable wall member that sandwich the clamp element need only be finished with a predetermined accuracy.

When holding the movable member to the fixed wall member,
Since the movable wall member can be adjusted in any way by the tightening means, the absolute value of the length does not have to be the same as the distance between the two fixed wall members as in the prior art.

This means that the length, or outer dimension, of the clamping element and
Compared to the extremely difficult processing and assembly process of matching the distance between two fixed wall members, that is, the inner dimensions, with a predetermined high precision, it is much easier to align the end face of the clamp element to a predetermined flatness and parallelism. This means that it is only necessary to process the wall surfaces of the fixed wall member and the movable wall member that sandwich the clamp element to a predetermined level of flatness.

Further, the movable wall member can be easily moved by the tightening means.

Therefore, when the movable member is damaged or its performance deteriorates and it becomes necessary to replace it, the movable member can be replaced very easily.

Furthermore, by adjusting the degree of tightening of the tightening means, the rigidity of the piezoelectric actuator itself can be adjusted.

Therefore, for example, in applications such as coarse movement devices for scanning tunneling microscopes, movement is performed with ultra-high precision on the nanometer scale, and the influence of resonance with external vibrations cannot be ignored. According to the actuator, it is possible to eliminate this influence.

〔Example〕

FIG. 1 is a detailed explanatory diagram of the present invention.

In the figure, a fixed wall member 2.3, a movable wall member 4, and two fixed wall members 2 that constitute the piezoelectric actuator 1 are shown.
．． The two side plates 8 that fix the frame 3 are all made of rust-free steel, and are precisely machined by cutting and polishing.

In addition, screws made of stainless steel are used as the tightening means 9, and two screws from the fixed wall member 2 and four screws each from the fixed wall member 3, a total of six wood screws, are used for the movable wall member 4. was adjusted so that the movable wall member 4 could be moved.

Two clamp elements 6a, 6b forming the movable member 5,
The linear drive element 7 is made of laminated lead zirconate titanate piezoelectric ceramics, and the clamp element 6a
, 6b is 5X5X1Bmm, linear drive element 7 is 5
It was manufactured by fixing square pillars measuring 5 x 9 mm in an H shape.

Further, on the clamp element 6a of the movable member 5, a round bar made of stainless steel and having a diameter of 3 mm was fixed as a movable bar 10 to be connected to an object to be moved (not shown).

The movable rod 10 is assembled so as to pass through one side plate 8, and when the clamp elements 6a and 6b are expanded by applying a +IOV pulse to electrodes (not shown), the fixed wall member 3 and the movable wall The tightening means 9 was adjusted so that a tightening pressure of 10 kg was applied by the member 4.

The piezoelectric actuator 1 assembled in this way is controlled by a control device (not shown) when each element is extended to an electrode (not shown) provided on each of the clamping elements 6a, 6b of the movable member 5 and the linear drive element 7. is +10■
When each element contracted, a DC pulse voltage of 10 cm was applied at a repetition rate of once per second, and the operation was confirmed according to the driving procedure shown in FIG. 2(B).

As a result, it was confirmed that the device operated with the same accuracy as the conventional example.

Furthermore, it can be confirmed that the movable member 5 can be replaced very easily by adjusting the tightening means 9, and furthermore, since the absolute value of the length of the clamp elements 6a and 6b can be arbitrarily selected, processing is also very easy. This was confirmed.

Furthermore, it has been confirmed that when the tightening pressure of the tightening means 9 is changed to increase the rigidity, the natural frequency of the piezoelectric actuator 1 is also increased, and the influence of external vibrations can be reduced.

Here, various piezoelectric materials can be applied to the materials of the clamp element and the linear drive element that constitute the movable member.
Various modifications are possible.

In addition, screws were used as a simple means for tightening the movable wall member, but the number and position of the screws can be modified in various ways. Other support means are also possible.

As described above, in the piezoelectric actuator according to the present invention, since the movable member is held between the fixed wall member and the movable wall member movably supported by the tightening means, the accuracy during processing and assembly can be reduced. Instead, if the tightening degree of the tightening means is controlled, the rigidity of the actuator can be made extremely high, and the influence of external vibrations can be reduced.

Therefore, it will greatly contribute to the development of fields where objects must be moved with high precision, such as exposure equipment for fine patterning and coarse movement equipment for scanning tunneling microscopes.

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIG. 2 is an explanatory diagram of a conventional piezoelectric actuator. In the figure, 1 is a piezoelectric actuator, 2.3 is a fixed wall member, 4 is a movable wall member, 5 is a movable member, 6a and 6b are clamp elements, 7 is a linear drive element, 8 is a side plate, 9 is a tightening means, 10 is a movable rod. Agent Patent Attorney Sada Igata − Un+ θ Month 777 Actually λ Self I Listed [ ] Month m 1st

Claims (1)

[Claims] Two opposing fixed wall members (2, 3) fixed to two opposing side plates (8), and a wall protruding from the wall of the fixed wall members (2, 3). The fixed wall members (2, 3) are secured by a plurality of fastening means (9).
A movable wall member (4) supported so as to be able to move in parallel in the gap between
and two clamp elements (6a, 6b) made of piezoelectric material.
a movable member (5) to which a linear drive element (7) is fixed in an H-shape; and a movable rod (10) fixed to the clamp element (6a).
and the movable rod (10) extends through the side plate (8) and the clamp element (6a) of the movable member (5).
, 6b) are held between the fixed wall member (3) and the movable wall member (4) by the tightening means (9).