JPH05137353A - Plane driving piezoelectric motor - Google Patents

Abstract

PURPOSE:To make it possible for a moving member to move linearly by forming pointed teeth each having inclined planes on a stator and providing piezoelectric elements to the movable member to allow it to advance or retract so that its detachable coupling parts can engage with or disengage from each of the teeth. CONSTITUTION:The teeth 2 of a stator 1 are formed in quadrangular pyramids each having inclined planes in the directions X and Y. A moving member 3 comprises a plurality of pressure members 5 having actuators (AC) 6 and coupling parts 8 arranged along both edges in the direction X of the support of a flat rectangular member. A plurality of pressure members 4 comprising the ACs 6 and coupling parts 7 are arranged between the arrays of the pressure members 5 along both edges in the direction Y. The motion in the direction X is such that when a voltage is impress on the AC 6a, it is extended so that the pointed end of an X coupling part 7a engages with the interval between the corresponding two teeth 2 of the stator 1. Then, when the AC 6b is extended and the AC 6a is contracted, the X coupling part 7b engages with the inclined planes of the teeth 2 to provide a force by the pressure of the AC 6b, which enables the moving member 3 to advance in the direction indicated by an arrow for movement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar drive type piezoelectric motor which obtains a planar displacement by using an expansion / contraction motion of a piezoelectric element as a drive source.

[0002]

2. Description of the Related Art In a conventional motor, a plurality of iron pieces are arranged at a constant pitch on the outer circumference of a rotor, and a plurality of magnetic poles are arranged on the inner circumference of a stator at a constant angle with respect to the iron pieces of the rotor. Then, there is a stepping motor that rotates a rotor by a constant angle by sequentially exciting each magnetic pole to attract an iron piece.

However, in the stepping motor that rotates the rotor by attracting the iron piece of the rotor due to such magnetic force, it is ensured at the position where the magnetic pole and the iron piece are aligned against the inertial force generated when the rotor is rotated. It was difficult to stop. Therefore, as a motor for improving this point, a piezoelectric motor proposed in Japanese Patent Laid-Open No. 61-22775 has been proposed. As shown in FIG. 10, this piezoelectric motor has a structure in which one surface of a disk-shaped rotor 20 has a rotor 20
A plurality of engaging teeth 21 each having an isosceles triangular cross-sectional shape are formed radially at a constant pitch around the rotation axis of the rotor 20, and a plurality of levers 22 are arranged to face one surface of the rotor 20. The levers 22 are arranged radially with respect to the rotation axis of the rotor 20, and are movable back and forth in the axial direction of the rotor 20 (the direction orthogonal to the paper surface in FIG. 10). And, in the portion of the lever 22 facing the engaging teeth 21,
Plural feed teeth 23 which can be meshed with the engagement teeth 21 and have the same pitch as the engagement teeth 21 are formed.

Here, the positional relationship between the feed teeth 23 of each lever 22 and the engagement teeth 21 will be described when the number of levers 22 is five. Assuming that they are aligned and meshed with each other, the feed dog 23 at position B is displaced from the engaging tooth 21 by 1/5 pitch, 2/5 pitch at position C, 3/5 pitch at position D, and 4/5 at position E. It is formed so as to be shifted in pitch.

On the surface of the lever 22 opposite to the surface facing the rotor 20, a retractable actuator (not shown) is arranged perpendicular to the surface on which the engaging teeth 21 of the rotor 20 are formed. .. In this actuator, when a large number of piezoelectric ceramics are stacked and a voltage is applied to each piezoelectric ceramic, the actuator extends in the stacking direction due to the total strain of the piezoelectric ceramics, and the lever 22 causes the engaging teeth 2 of the rotor 20 to move.
When the voltage is stopped by applying the voltage, the actuator 22 contracts and the lever 22 moves backward from the surface where the engaging teeth 21 of the rotor 20 are formed.

In this piezoelectric motor, when the feed tooth 23 of the lever 22 at the position a shown in FIG. 10 is started to rotate from the state of being engaged with the engaging tooth 21, the actuator corresponding to the lever 22 at the position b is extended. And position lever 22
The actuator corresponding to is contracted. At this time, the feed dog 23 of the lever 22 at the position B is the engaging tooth 2 of the rotor 20.
1 is located on the inclined surface in the clockwise direction, the feed tooth 23 pushes the inclined surface of the engaging tooth 21 by the forward movement of the lever 22 to rotate the rotor 20 in the clockwise direction and engage the feed tooth 23. The rotor 20 is rotated until the teeth 21 are completely meshed. At this time, the rotor 20 rotates by 1/5 pitch.

Thereafter, similarly, the actuator corresponding to the lever 22 at the position C is extended and the lever 22 at the position B is extended.
If the actuator corresponding to is contracted, the rotor 20 rotates by 1/5 pitch. Here, if the expansion and contraction of the actuator corresponding to the positions a to e are repeated in a constant cycle, the rotor 20 can be rotated at a constant speed.

In this piezoelectric motor, since the rotor is rotated by mechanical engagement, the rotation stop position can be made accurate.

[0009]

However, when linear positioning is performed using the above-described piezoelectric motor, the piezoelectric motor performs a circular operation, so it is necessary to convert the circular operation into a linear operation. There is a problem that the reduction in accuracy due to this conversion cannot be avoided. Further, in applications in which planar positioning, which is a further development of linear positioning, is desired, there is a problem that the positioning accuracy is further deteriorated due to a decrease in accuracy when converting a circular motion to a linear motion. ..

The present invention has been made in view of the above points, and it is an object of the present invention to provide a planar drive type piezoelectric motor capable of accurately performing planar positioning.

[0011]

In order to achieve the above object, the present invention comprises a planar stator and a mover movably arranged on the stator, and is orthogonal to the stator. A plurality of teeth are arranged in a row in two directions, and each tooth is formed in a pointed shape with inclined surfaces on both sides in the two directions, and an engaging portion that can be engaged with and disengaged from the teeth, and this engagement. The movable element is provided with a plurality of pressing members each including a stretchable actuator that uses a piezoelectric element as a drive source to move the joint portion forward and backward so as to engage and disengage from the tooth.

The teeth may be formed in a conical shape in order to facilitate the formation of the teeth. Further, for example, when it is desired to make the positioning accuracy different in two directions, the inclination angles of the inclined surfaces of the teeth may be made different in the two directions. In addition, as an example of a specific method of forming the teeth and the pressing body for accurately performing the planar positioning, a plurality of teeth are arranged in a row at a constant pitch in each of two directions orthogonal to the stator, and When the mover is provided with a plurality of pressing bodies at a constant pitch in each of the two directions, and one direction is the X direction and the other direction is the Y direction, the pitch Px of the pressing bodies in the X direction and the Y direction. Px = nx · px + px / mx Py = ny · py + py / my where Px = nx · px + px / mx where mx is the number of pressing members in the X direction my: Number of pressing members in the Y direction px: Pitch in the X direction of teeth py: Tooth A positive integer including the pitch nx, ny: 0 in the Y direction.

[0013]

The present invention has the above-mentioned configuration,
Enables linear movement of the mover, which eliminates the need to convert circular movement to linear movement as in the past, and enables highly accurate positioning, and allows the mover to move linearly in two directions. By
The mover can be operated in any direction within the plane, that is, the mover can be moved in the plane, and thus the planar positioning can be performed with high accuracy. It is a thing.

[0014]

(Embodiment 1) FIGS. 1 to 5 show an embodiment of the present invention. In the planar drive type piezoelectric motor of this embodiment, as shown in FIG.
As shown in FIG. 3, it is composed of a planar stator 1 and a mover 3 movably arranged on the stator 1. here,
As a method of movably providing the mover 3 on the stator 1, for example, the mover 3 may be magnetically attracted (or repelled) to and held by the stator 1. However, another method may be used as long as the mover 3 is movable on the stator 1. On the surface of the stator 1 facing the mover 3, a plurality of teeth 2 are arranged in a row at a constant pitch along two directions (X and Y directions in FIG. 1) orthogonal to each other. In addition, the movable element 3 includes a plurality of actuators 6 each having a piezoelectric element as a driving source, which is distorted by applying a voltage.
Further, there are provided pressing bodies 4, 5 each of which is attached to the tip of the actuator 6 and comprises a plurality of engaging portions 7, 8 which can be engaged with and disengaged from the teeth 2.

As shown in FIG. 8A, the teeth 2 of the stator 1 are formed in a regular quadrangular pyramid shape having slopes on both sides in the X and Y directions. In addition, in the present embodiment, the mover 3 has the structure shown in FIG.
As shown in (b), a plurality of pressing bodies 5 each including an actuator 6 and an engaging portion 8 are provided along both edges of the flat rectangular parallelepiped base in the X direction, and the pressing bodies 5 are arranged along both edges in the Y direction. The actuator 6 is provided between the pressing bodies 5 arranged in a row.
A plurality of pressing bodies 4 each including an engaging portion 7 and an engaging portion 7 are provided. Here, each of the engaging portions 7 and 8 has a shape in which a triangular prism is laterally oriented, and the engaging portion 7 has inclined surfaces on both sides thereof in the stator 1.
Is formed as a direction along the slope of the tooth 2 of the X direction,
The inclined surfaces on both sides of the engaging portion 8 are formed along the Y-direction inclined surfaces of the teeth 2 of the stator 1. Therefore, in the following description, the engaging portions 7 and 8 will be referred to as the X engaging portion 7 and the Y engaging portion 8 respectively.
Will be identified and called.

Then, the pitch of the X engaging portions 7 adjacent to each other is set to Px as shown in FIG.
When the pitch in the X direction is px, Px = nx · px + px / mx, where mx is a positive integer including nx: 0, which is the number of pressing bodies 4 in the X direction, and the pitch between adjacent Y engaging portions 8 3B and Py is the pitch of the teeth 2 adjacent to each other in the Y direction, Py = ny · py + py / my, where my: the number of pressing bodies 5 in the Y direction ny: It is a positive integer including 0. In order to simplify the following description, as shown in FIGS. 2 and 3, the above mx = my = 3, nx =
The case where ny = 2 is described.

The operation of the plane drive type piezoelectric motor will be described with reference to FIG. First, the driving operation in the X direction of the planar drive type piezoelectric motor will be described. Here, for convenience of explanation, the X engaging portions 7 will be described as 7a, 7b, and 7c in order from the left side in FIG. 1, and the actuators 6 corresponding to each will be described as 6a, 6b, and 6c.
Now, a voltage is applied to the actuator 6a, the actuator 6a expands, and as shown in FIG. 4 (a), the tip of the X engaging portion 7a is applied to a portion between two teeth 2 of the stator 1 facing each other. Assume that they are engaged with each other.

In this state, when the actuator 6b is expanded and the voltage applied state is released from the actuators 6a, and contracted, the X engagement portion 7b engages with the inclined surface of the tooth 2 and the actuator at this time is engaged. A force in the traveling direction indicated by an arrow in FIG. 4 is applied to the mover 3 by the pressing force received from 6b, and the mover 3 moves. Then, the X engagement portion 7b moves to a position where it is completely engaged between the teeth 2 as shown in FIG. 4 (b). Here, since the pitch Px of the X engagement portion 7 is set to 2px + px / 3 as described above, the mover 3 has p
Move x / 3.

Next, the actuator 6c is expanded and the actuator 6b is contracted. At this time, the movable element 3 is further moved in the traveling direction by the pressing force received from the actuator 6c, and the X engaging portion 7 is moved as shown in FIG.
Move to a position where c is fully engaged between teeth 2. Hereinafter, if the actuators 6a, 6b and 6c are cyclically expanded and contracted in such a manner that the actuator 6a is extended and the actuator 6c is contracted, as shown in FIG.
Proceed by a predetermined pitch in the direction of the arrow inside.

When the actuators 6a, 6b and 6c are cyclically expanded and contracted in the reverse order of the above-mentioned case, the actuators 6a, 6b and 6c can be moved in the direction opposite to the direction indicated by the arrow in FIG. Although the above description is for the driving operation in the X direction, the same driving operation is performed for the Y direction as well.
It can be moved by / 3. In other words, the planar drive type piezoelectric motor of this embodiment can be a motor that moves in steps of px / 3 in the X direction and py / 3 in the Y direction.

In the above description, the case where the driving in the X direction and the driving in the Y direction are performed independently has been explained, but (a) to (a) of FIGS. (C)
When driving in the X direction and driving in the Y direction are performed at the same time, as shown in FIG. 5, it is possible to move in a direction having an angle with respect to the X and Y directions. For example, the pitch p in the X and Y directions
When x and py are equal, 45 ° with respect to the X and Y directions
The mover 3 can be moved in the direction of. further,
It is also possible to change the moving direction of the mover 3 by changing the pitch and the driving speed in the X and Y directions.

(Embodiment 2) FIGS. 6 and 7 show still another embodiment of the present invention. This embodiment shows a driving method of a planar drive type piezoelectric motor for further improving the positioning accuracy. The driving method of this embodiment will be described for the case where the mover 3 is driven in the X direction. FIG. 6A shows a state in which the X engagement portion 7c is engaged between the teeth 2, and FIG. 6C shows that the X engagement portion 7a is driven by one step from the state of FIG. The state which engaged between the teeth 2 is shown. In this one step period, when the actuator 6c is contracted and the actuator 6a is expanded at the same time, the X engagement portion 7
6 (b) in which a and 7c simultaneously engage with the inclined surface of the tooth 2
The states shown in exist.

Therefore, as shown in FIGS. 7B to 7D, if the three actuators 6 are gradually expanded and contracted and the expanded and contracted state is stopped midway, one step (FIG. 6B) is performed. The mover 3 can be positioned at a position between px / 3). That is, the positioning can be performed in one step or less. This can be similarly performed in the Y direction.

(Third Embodiment) By the way, it is also possible to combine the driving method of the above-mentioned planar drive type piezoelectric motor with the above-mentioned first and second embodiments. Specifically, a plurality of steps (1 step is p
/ 3) to move the desired distance (this is called coarse movement),
After the movement, the plurality of engaging portions 7 and 8 described in the second embodiment can be engaged with the tooth 2 at the same time to perform positioning (this is called fine movement). In this case, the mover 3 can be moved at high speed by coarse movement, and the positioning can be performed with high precision by fine movement. here,
The coarse movement step numbers Ux and Uy in the X and Y directions must satisfy the following equations.

Lx-px / 3 <Uxpx / 3 ≦ Lx Ly-py / 3 <Uypy / 3 ≦ Ly where Lx: distance to a predetermined position in the X direction Ly: distance to a predetermined position in the Y direction ( Embodiment 4) In each of the above embodiments, the teeth 2 of the stator 1 are
In the above, the case where the shape is a quadrangular pyramid shown in FIG. 8A has been described, but the shape may be a cone shown in FIG. 8B. In this case, it is not necessary to form the inclined surfaces in the X and Y directions on the teeth 2, that is, the inclined surfaces orthogonal to each other, and there is an advantage that the processing of the teeth 2 becomes easy.

(Embodiment 5) FIG. 9 shows still another embodiment of the present invention. In this embodiment, a tooth 2 having a quadrangular pyramid shape is used.
The apex angles of the respective surfaces in the X and Y directions are different as indicated by θx and θy. In this way, the moving distance of the mover 3 in one step can be made different.

[0027]

As described above, the present invention comprises a planar stator and a mover movably arranged on the stator, and has a plurality of teeth in two directions orthogonal to the stator. The teeth are formed in a row, and each tooth is formed into a pointed shape with inclined surfaces on both sides in the two directions, and an engaging portion that can be engaged with and disengaged from the tooth and an engaging portion that disengages the tooth from the tooth. Since the movable element is provided with a plurality of pressing bodies composed of an expandable and contractible actuator that uses a piezoelectric element that moves back and forth as a drive source,
Since the mover can be moved linearly, there is no need to convert the circular movement to the linear movement as in the conventional case, highly accurate positioning can be performed, and the mover can be moved linearly in two directions. The mover can be operated in any of the directions, that is, the mover can be moved in a plane, and thus planar positioning can be performed with high accuracy.

When the teeth are formed in a conical shape, the accuracy of the inclined surface is not required as in the case of the pyramid, and the teeth can be easily formed. Furthermore, if the angles of the inclined surfaces on both sides of the tooth are made different in the two directions, the positioning accuracy can be made different in the two directions, for example.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention.

2A to 2D are a perspective view, a plan view, a front view and a side view of a mover.

3 (a) and 3 (b) are explanatory views showing a formation state of teeth and a pressing body in each of X and Y directions.

FIG. 4 is an operation explanatory view when the mover is moved in one direction.

FIG. 5 is an operation explanatory diagram when the mover is simultaneously moved in the X and Y directions.

FIG. 6 is an operation explanatory diagram of still another embodiment.

FIG. 7 is an explanatory diagram of a method for driving an actuator in the above.

8A and 8B are perspective views showing teeth of different shapes.

9A to 9C are a plan view, a side view, and a front view showing still another tooth forming method.

FIG. 10 is an explanatory diagram of the structure and operation of a conventional piezoelectric motor.

[Explanation of symbols]

 1 Stator 2 Teeth 3 Mover 4,5 Pressing body 6 Actuator 7, 8 Engagement part

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[Procedure amendment]

[Submission date] February 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction content]

(Third Embodiment) By the way, it is also possible to combine the driving method of the above-mentioned planar drive type piezoelectric motor with the above-mentioned first and second embodiments. Specifically, a plurality of steps (1 step is p
/ 3) to move the desired distance (this is called coarse movement),
After the movement, the plurality of engaging portions 7 and 8 described in the second embodiment can be engaged with the tooth 2 at the same time to perform positioning (this is called fine movement). In this case, the mover 3 can be moved at high speed by coarse movement, and the positioning can be performed with high precision by fine movement. Here, positions
In order to shorten the placement time, it is desirable that the coarse motion step numbers Ux and Uy in the X and Y directions satisfy the following equations.
Yes.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

Lx-px / 3 <Ux · px / 3 ≦ Lx Ly-py / 3 <Uy · py / 3 ≦ Ly where Lx: distance to a predetermined position in the X direction Ly: predetermined position in the Y direction (Example 4) In each of the above examples, the teeth 2 of the stator 1
In the above, the case where the shape is a quadrangular pyramid shown in FIG. 8A has been described, but the shape may be a cone shown in FIG. 8B. In this case, it is not necessary to form the inclined surfaces in the X and Y directions on the teeth 2, that is, the inclined surfaces orthogonal to each other, and there is an advantage that the processing of the teeth 2 becomes easy.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

Claims (4)

[Claims] 1. A flat stator and a mover movably arranged on the stator, wherein a plurality of teeth are arranged in a row in two directions orthogonal to the stator and each of the teeth is arranged in a row. Is formed in a pointed shape with inclined surfaces on both sides in the above two directions, and an engaging portion that can be engaged and disengaged with the tooth, and a piezoelectric element that advances and retreats to engage and disengage the engaging portion with the tooth. A planar drive type piezoelectric motor, characterized in that a plurality of pressing bodies, each of which comprises a stretchable actuator as a drive source, are provided on the mover. 2. The plane drive type piezoelectric motor according to claim 1, wherein the teeth are formed in a conical shape. 3. A planar drive type piezoelectric motor, wherein the inclination angles of the inclined surfaces of the teeth are different in two directions. 4. A plurality of teeth are arranged in a row at a constant pitch in each of two directions orthogonal to the stator, and a plurality of pressing bodies are provided in the mover at a constant pitch in each of the two directions, and one direction is X-direction. Direction and the other direction is the Y direction,
Px = nx · px + px / mx Py = ny · py + py / my, where Px = nx · px + px / mx Py = ny · py + py / my, where mx is the number of pressing members in the X direction The planar drive piezoelectric motor according to claim 1, wherein the number of bodies px: pitch of teeth in X direction, py: pitch of teeth in Y direction, nx, ny: a positive integer including 0.