JPS6271480A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To lighten a piezoelectric actuator, and to enable drive at low voltage and fine displacement having high precision by constituting a piezoelectric displacement unit in which a tabular piezoelectric slip-effect element and a tabular piezoelectric transversal-effect element are joined and unified. CONSTITUTION:A piezoelectric displacement unit 10 is supported by a supporter 11 through support means 12, 13. The piezoelectric displacement unit 10 is composed by joining and unifying a piezoelectric transversal-effect element 16 and a piezoelectric slip-effect element 17. An adapter 19 consisting of a magnetic material or an abrasion-resistant material such as a rubber is fixed onto the surface of the piezoelectric slip-effect element 17 in order to efficiently transmit the movement of the piezoelectric displacement unit 10 over an object to be driven.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a piezoelectric actuator that utilizes deformation of a piezoelectric element.

(Technical Background of the Invention) Conventionally, in order to perform microfabrication or microobservation, a positioning table on which processing materials or observation materials are placed has been displaced by rotating a threaded shaft using a step motor. Ta. Therefore, the displacement accuracy for positioning is determined by the rotation angle accuracy of the motor and the screw accuracy of the drive shaft. However, these methods all depend on the mechanical processing precision of the motor's magnetic poles and shaft, and high precision cannot be expected.

Further, in an actuator using a step motor as described above, the stepper motor itself requires a relatively large space and weight, which limits its range of application.

Furthermore, conventionally, in a piezoelectric actuator that is displaced in proportion to the value of an input voltage, a small converting means (piezoelectric displacement unit) with a large stroke that can be arbitrarily displaced in the XY two-axis directions has not been found.

(Objective of the Invention) The present invention has been made in an attempt to eliminate the above-mentioned drawbacks of the prior art.
By combining the thickness and sliding effect, it is lightweight,
It is an object of the present invention to provide a piezoelectric actuator that is capable of fine displacement with high precision, can be driven at low voltage, and can arbitrarily take large strokes in two axial directions.

(Summary of the Invention) In order to achieve this object, according to the piezoelectric actuator of the present invention, a piezoelectric displacement unit is formed by joining a plate-shaped piezoelectric sliding effect element plate and a wedge-shaped piezoelectric effect element to form an integrated piezoelectric displacement unit. Do it like this.

(Embodiments of the Invention) The present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in each figure indicate similar objects.

1 and 2 show an embodiment of the invention.

In the figure, 10 is a piezoelectric displacement unit, 11 is a support for the unit 10, 12 and 13 are support means, 16 is a piezoelectric transverse effect element polarized in the direction of the arrow (d30), and 17 is a piezoelectric transverse effect element polarized in the direction of arrow B. Polarized thickness-slide effect (dI
5) is a piezoelectric slip effect element, and 19 is an adapter.

The support means 12, 13 fix the piezoelectric element so as to prevent it from shifting in the lateral direction, and support both ends of the piezoelectric element. As shown in FIGS. 1 and 2, 123 and 13a are stepped portions on which both ends of the piezoelectric element are placed and supported. Moreover, 12b and 13b are wall portions that abut the ends of the piezoelectric elements and extend in the thickness direction thereof. The inner height h of these wall portions 12b, 13b is the piezoelectric element 16.1.
approximately equal to the total thickness of 7. However, they do not necessarily have to be equal; the point is that there is a lateral clamping effect on the piezoelectric element. Side wall portions 12C, 12d and 13c which are continuous with the wall portions 12b and 13b and have the same height h;
13d is formed by bending in an L-shape from the wall portions 12b and 13b. These side wall portions 12c, 12d,
13c and 13d are also continuous to the stepped portions 12a and 13a in an L-shape.

The piezoelectric transverse effect element 16 and the piezoelectric sliding effect element 17 are made of, for example, lead zirconate titanate, and both have a plate shape with approximately the same dimensions. 16a-173 is the thick part, and the flat upper and lower surfaces, which have a larger area compared to this, are the main surface 16s.
・It is 178. This main surface is 16s.

Needless to say, electrodes are attached to 16S, 17S, and 17S.

The piezoelectric transverse effect element 16 and the piezoelectric glide effect element are integrally joined by a method such as adhesion, each having one main surface.

An adapter 19 is fixed to the non-bonded main surface 17S of the piezoelectric sliding effect element 17. The adapter 19 is for efficiently transmitting the motion of the piezoelectric displacement unit 1-10 to the driven object, and is made of a wear-resistant material such as a magnetic material or rubber. The adapter 19 has a relationship such as contact or coupling with the driven body of the positioning table, and transmits the behavior of the adapter 19 to the driven body. .

By the way, in this embodiment, a case has been described in which two piezoelectric transverse effect elements 16 and one piezoelectric sliding effect element 17 are used, but the number is not limited to this. For example, it goes without saying that a total of four elements, two each, may be used. However, when using multiple layers, it is necessary to balance the symmetry, and of course it is also necessary to pay attention to the connection direction.

The piezoelectric actuator as described above operates as follows.

When a voltage is applied to the piezoelectric transverse effect element 16, the unit 10 is displaced in the 10M direction depending on the polarity of the applied voltage. Furthermore, when a voltage of the opposite polarity is applied, the unit IO is displaced in the -M direction according to the magnitude of the voltage.

When a voltage is applied to the piezoelectric sliding effect element 17, the unit 10 undergoes shear deformation and is displaced in the N direction according to the magnitude of the voltage.

Furthermore, if voltages with different phases are applied to both piezoelectric displacement means 16 and 17, M
It is displaced in the direction and position that is the combination of the direction and the vector in the N direction.

Since the amount of displacement in the above displacement is accurately proportional to the magnitude of the applied voltage, the amount of displacement can also be accurate.

FIG. 3 shows a piezoelectric linear mortar according to another embodiment of the invention.

According to this embodiment, units IOA and IOB similar to the piezoelectric displacement unit 10 of FIG. 1 are provided.

The units I-1OA and IOB are aligned and fixed on the base plate 31 so that one direction of the units coincides with each other. At the top of each unit l-1OA and IOH, that is, at the top of the piezoelectric sliding effect element 17, adapters 19A and 19B are installed, respectively.
has been fixed.

A drive shaft 39 that moves in the same direction as the alignment direction of the units is arranged above the units IOA and IOB. This drive shaft 39 is connected to each unit 10A, IO
B, to be more precise, is held between the adapters 19A and 19B and a roller 38 rotatably fixed to the upper plate 32.

The base plate 31 constitutes a casing together with the top plate 32 and the end plates 33,34. End plate 33.
34 has a hole 33 through which the drive shaft 39 passes.
A, 34A is formed.

Note that when no voltage is applied to the piezoelectric displacement units l-1OA and IOB, the drive shaft 39 is held between the rotary roller 38 and the piezoelectric displacement units OA and IOB as described above, and a small force will not be applied to the drive shaft 39. It doesn't move. The piezoelectric transverse effect element 16 and the piezoelectric sliding effect element 17 of each piezoelectric displacement unit OA and IOB are joined as described above to perform bimorph behavior, and the polarization direction of each element is indicated by the arrows A and B in FIG.
It is processed in the same way.

The operation of the near motor as described above will be explained next.

The sequence of operations will be explained in order.

(1) A driving voltage is applied to the piezoelectric transverse effect element 16 of the piezoelectric unit OA, and the unit 10A is contracted in the -M direction.

(2) Similarly, a driving voltage is applied to the piezoelectric sliding effect element 17 of the piezoelectric unit l-1OA, and the unit OA is shifted in the 10N direction. Therefore, the UNINORI-1OA is displaced diagonally downward to the left, and the clamp on the shaft 39 is released.

(3) Apply a voltage with the opposite polarity to the previous sections (1) and (2),
Clamp the shaft 39 with the unit IOA.

(4) A driving voltage is applied to the piezoelectric transverse effect element 16 of the piezoelectric unit 10B to contract the unit 10B in the -M direction, and a driving voltage is applied to the piezoelectric slip effect element 17 of the piezoelectric unit l-10B, so that the unit l- Shift 1OA in the direction of 10N. Unit IOB unclamps shaft 39.

(5) Apply a voltage with the opposite polarity to (2) to the piezoelectric slip effect element 17 of the piezoelectric unit 10A, and the unit 10A
Displace it in the N direction. The shaft 39, which is held between the rotating roller blades, moves in the -N direction.

(6) In the piezoelectric transverse effect element 16 of the piezoelectric unit 10B (1
), a voltage of opposite polarity is applied to shift the unit 10B to the clamp state.

(7) Unit l-1 using the same operations as in the previous section (1) and (2).
Release the OA clamp.

direction. The shaft 39 held between the rotating roller 38 moves in the -N direction.

(9) Put the piezoelectric Unino l-1OA into the clamped state by the same operation as in the previous section (3).

(10) Release the piezoelectric unit QB from the clamped state by performing the operations in (1) and (2) above.

(11) Thereafter, the shaft 39 can be sequentially moved in the -N direction by not repeating the same operation.

In the above explanation, each of the operations (1) to (1) was explained to be performed at different times, but (4), (5), and (
The operations 7) and (8) may be performed simultaneously. It can be seen that for this purpose, the piezoelectric sliding effect elements 17 of the units 10A and 1OB may be electrically connected in parallel and arranged so that they operate in opposite directions.

FIG. 4 is a time chart illustrating the operation of the embodiment shown in FIG. 3, and FIG. In addition, (C) and (d) in the same figure are unit number 0A-1, respectively.
FIG. 3 is a waveform diagram of a voltage applied to a piezoelectric slip effect element of 0B.

However, it is not necessary to use two channels (C) and (d), and either (C) or (d) is sufficient. For this reason, they are arranged in parallel in opposite directions.

In addition, the piezoelectric sliding effect element is a piezoelectric unit IOA・10B.
It may be provided only on either one of them. In this case, the step amount by which the shaft 39 moves is halved.

If it is desired to move the shaft 39 in the opposite direction (+N direction), the operations in each of the above sections may be reversed, that is, the phase of the input applied voltage may be reversed.

The number of steps, that is, the moving speed, is determined by the frequency of the input signal, and its upper limit is determined by the charging speed of the piezoelectric unit and the mechanical resonance point of the drive system, and is usually 1000 to 3 per second.
The maximum movement speed is 2-3 tmx/sec at 000 steps.

When finely adjusting the amount of movement, use 10A/1 for each unit.
This objective can be achieved by finely adjusting the voltage applied to the piezoelectric glide effect element of oE3 or by adjusting the frequency of repetition.

can.

In the above embodiment, the piezoelectric unit was provided only on one side of the shaft 39, and the rotating roller 38 was provided on the other side, but the piezoelectric unit may be provided on both sides, and the shaft 39 may be held between both sides.

Note that the movement relationship between the shaft 39 and the piezoelectric units l-1OA and IOB is relative, and it is also possible to keep the shaft 39 fixed and move the casing including the units OA and IOB in exactly the same way. be.

FIG. 5 shows a piezoelectric linear motor according to still another embodiment of the invention. According to this embodiment, the piezoelectric unit itself moves.

In the figures, 10A1 to 10A3 (abbreviated as 10 or IOA as necessary) and l0BI to 1OB3 (abbreviated as IOB or 10 as necessary) are piezoelectric displacements similar to those explained in FIGS. 1 and 3. 4f is a base plate on which a piezoelectric displacement unit is mounted and the wheel 40 is rotatably fixed; 42 is a track that regulates the moving direction of the wheel 40; 43 is the thickness of the piezoelectric displacement unit. This is a reaction means that applies a reaction force to a displacement in a direction.

As can be seen from FIG. 5(C), the piezoelectric displacement unit is
A total of 6 pieces are provided in two rows in the longitudinal direction and three rows in the direction perpendicular to this. Unit l0AI, 10A2.10A
3 (these will be referred to as A units if necessary) all operate in the same way, and units 10B 1. IOB 2
．． IOB 3 (these are referred to as B units if necessary) all operate in the same way.

The wheels 40 and the base plate 41 constitute a truck which is a moving body.
There is. The wheel 40 consists of a disc 40A and a shaft 49B that connects the disc. Such a wheel 40 is rotatably fixed to the base plate 41 side by a well-known bearing or the like. A flat track 4 protruding from these wheels 40
Holding 2.

The configuration of the wheels 40 in relation to the track 42 may be arbitrary. The rollers may be fitted into the concave track.

The track 42 and the reaction means 43 are continuous in parallel, and the interval S between them is such that the movable body does not move when no voltage is applied to the piezoelectric displacement unit.

In addition, the adapter on the unit is used as a magnet and the reaction means 4
3 can be made into a magnetic material.

The operation of the linear motor according to this embodiment is similar to that of the embodiment shown in FIG. 3, and is a relative movement in which a moving body equipped with piezoelectric displacement units IOA and 10B is displaced instead of the drive shaft. . In this case, it is assumed that the piezoelectric transverse effect element and the piezoelectric sliding effect element of each piezoelectric displacement unit 1-1OA.10[1 are the same as in the previous embodiment.

Such a near motor is small and lightweight, and is capable of accurate displacement, so it is particularly effective as a motor for moving a printer head.

FIG. 6 shows an embodiment in which the vertical position of the embodiment shown in FIG. 5 is reversed. This differs from the embodiment shown in FIG. 5 in that the wheel 40 is removed, and the magnetized piece 4 is attached to the adapter 19 as shown in FIG.
6 is attached and moved on the magnetic rail 45 in the same operating procedure as in the case of FIG. Also (C
) As shown in the figure, a plate 47 is provided to prevent the moving body from falling off the rail 45. Note that a rolling member such as a roller may be attached to the lower part of this plate 47 to facilitate movement.

FIG. 7 shows a modification of the piezoelectric actuator shown in the embodiment of FIG. 1, and it is natural that the actuator of this embodiment can be applied to the piezoelectric displacement unit of the embodiment of FIGS. 3 and 5. It is possible.

According to the figure, two piezoelectric shear effect elements 17A and 17B, which exhibit a piezoelectric thickness shear mode (d15) and are polarized in the direction of the arrow, are fixed on a support 11.

A piezoelectric transverse effect element 16A exhibiting a longer piezoelectric transverse effect (d31) is integrally bonded onto this piezoelectric slip effect element 17B, and a similar piezoelectric transverse effect element 16B is further disposed on top of this element 16A. They are glued together in a bimorph state. An adapter 19 is fixed to the upper end of the piezoelectric transverse effect element 16B opposite to the elements 17A and 17B. still,
The arrows shown in FIG. 7 indicate the directions of polarization that function when connected in parallel.

Further, in this embodiment, two effect elements are used for each effect element, for a total of four elements, but this is only an example.

This is because consideration is given to taking the base from the outside of the piezoelectric element9.
The number of sheets is not limited to this. Furthermore, a bimorph structure may be used in which either one of the piezoelectric transverse effect elements 15A and 16E3 is replaced with an elastic plate made of metal or the like.

(Effect of the invention) According to the invention, by configuring as above 9,
It is possible to obtain a piezoelectric actuator that is lightweight and thin, is capable of fine displacement with high precision, and can be arbitrarily displaced in the XY biaxial directions and has a large amount of displacement. Therefore, by using this piezoelectric actuator, a linear step motor that can operate at high speed and with high precision can be realized.9 For example, it can be used for fine positioning of tools under a microscope, or for driving printer heads that frequently make linear movements. Can be used as a motor for

[Brief explanation of drawings]

FIG. 1 is a side view (a) and a perspective view (b) of a piezoelectric actuator according to an embodiment of the present invention, FIG. 1 is a perspective view of a main part of an embodiment of the invention, and FIG. FIG. 4 is a time chart explaining the operation of the embodiment of FIG. 3, and FIG. 5 is a side view of a piezoelectric linear motor according to still another embodiment of the present invention. (
a), front view (b) and plan view (C), Fig. 5
FIG. 7 is an explanatory diagram of a modification of the embodiment shown in FIG. 1, showing a modification of the embodiment shown in FIG.・ 10... Piezoelectric six-position unit, 11... Support body, 1
2.13... Supporting means, 16... Piezoelectric transverse effect element,
17... Piezoelectric sliding effect element, 19... Adapter.

Claims (1)

[Claims] (1) A piezoelectric actuator having a piezoelectric displacement unit which is an integrated piezoelectric displacement unit made by joining a plate-shaped piezoelectric sliding effect element and a plate-shaped piezoelectric transverse effect element.