JP2006238639A - Ultrasonic motor and x-y shifter using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor by which one movable member is driven in X and Y axial directions with compact configuration. <P>SOLUTION: The motor includes a support member 16 with a three-point support 16b formed in a recess 16c which is formed in a central portion, three piezoelectric elements 14 individually supported by the three-point support 16b of the support member 16, a movable member 12 which is fixed to the other end 14a of these three piezoelectric elements 14 and is protruded from the recessed portion 16c, and slits 18 which are formed at the support member 16 and apply a pre-load to each piezoelectric element 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic motor and an XY moving device.

An ultrasonic motor, also called a piezoelectric motor, causes vibration using a piezoelectric element that is displaced by applying a voltage, drives a movable member by the vibration, and relatively controls the controlled member by the driving force of the movable member. It is something that moves.
In recent years, attempts have been made to use an ultrasonic motor in the XY plane that is small and can provide a large holding force with respect to a controlled member when stopped.

  For example, as an ultrasonic motor of this type, in the technique described in Patent Document 1, as shown in FIG. 5, the piezoelectric element 160 has a rectangular plate shape, and the substrate is placed on one of the main surfaces of the piezoelectric substrate. An electrode 140 is arranged to divide the main surface into four, and a ground electrode (not shown) is provided on the other main surface. These electrodes 140 are individually provided in a state of being insulated from each other, and the respective electrodes located diagonally to each other are electrically connected to each other by the conductive wire 220. The driving circuit of the ultrasonic motor 100 is composed of two AC voltage sources, and a voltage whose phase is shifted by π / 2 is applied to each of the diagonally connected electrodes. Generates vibration in the longitudinal longitudinal vibration mode (reference Z direction in the figure) that expands and contracts in the longitudinal direction and bending vibration mode (sign ± X direction in the figure) that bends in the short direction of the rectangular plate. Then, an elliptical motion in which both vibration modes are combined is obtained in the movable member 120, and the controlled member is relatively moved using the elliptical motion in the movable member 120 as a driving force.

Here, when the ultrasonic motor is used as a linear motor, if the main surface is configured as a single surface, the controlled member can be relatively moved only in one direction on the XY plane. However, when the main surface is constituted by two surfaces, the controlled member can be relatively moved in any direction on the XY plane by driving one movable member (hereinafter referred to as “X”). -Y drive)). For example, in the technique described in Patent Document 2, as shown in FIG. 6, a configuration of an ultrasonic motor 200 that is configured by two surfaces in which a main surface 260 intersects one movable member 220 and can be driven in an XY manner. An example is disclosed.
JP-A-5-3688 JP 7-184382 A

However, in the above-described configuration example of the ultrasonic motor that can be driven in the XY direction, the drive circuit needs to be configured by at least four AC voltage sources, and thus the configuration and control of the ultrasonic motor are complicated.
In addition, since the bending vibration generated in the short direction in each rectangular plate shape of the two intersecting main surfaces is synthesized and the entire ultrasonic motor main body vibrates while being bent in a complicated manner, the ultrasonic motor It becomes difficult to grasp the operating state of However, if the X direction and the Y direction are separately configured to facilitate the configuration and control of the ultrasonic motor, an ultrasonic motor that can be driven XY by a single movable member can be realized with a compact configuration. It becomes difficult.
The present invention has been made paying attention to such problems, and an ultrasonic motor capable of driving one movable member in an XY manner with a compact configuration, and an XY moving apparatus using the ultrasonic motor. It is intended to provide.

In order to solve the above problems, the invention according to claim 1 is an ultrasonic motor, wherein a support member having a three-point support portion formed in a recess formed in a central portion, and the three points of the support member. It is characterized by comprising three piezoelectric elements that are individually supported by the support portion, and a movable member that is fixed to the other end of the three piezoelectric elements and protrudes from the recess.
The invention described in claim 2 is an XY movement device using the ultrasonic motor according to claim 1, wherein the ultrasonic motor according to claim 1 and the movable member of the ultrasonic motor are provided. A relative movement member that moves in contact with the ultrasonic motor, and a pressing force applying member that applies a pressing force between the relative movement member and the ultrasonic motor.

  According to the present invention, it is possible to provide an ultrasonic motor capable of two-dimensionally driving one movable member with a compact configuration, and an XY moving device using the same.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. In this embodiment, the ultrasonic motor according to the present invention is used in an XY plane, that is, used in an XY moving device in which a controlled member is configured to be driven in XY by a single movable member. It is.
First, a configuration example of an XY moving device including an ultrasonic motor 10, a controlled member 51, and a pressing force applying member that applies a pressing force to the ultrasonic motor 10 according to the present invention will be described with reference to FIG. To do.

  As shown in the figure, the configuration example of the XY moving device includes a base 101, a pair of blocks 102 and 103 supported on the base 101 from below, and a shaft portion 104a on which a male screw is formed. A pressing force applying member having a handle 104 is provided. The entire ultrasonic motor 10 and the controlled member 51 are placed on the block 103 of the pressing force applying member. The controlled member 51 is movable in the XY plane by a linear guide (not shown), for example, and is restrained in the Z-axis direction (vertical direction in the figure).

  Specifically, the handle 104 of the pressing force applying member has a shaft portion 104 a, and the shaft portion 104 a is screwed into a female screw 101 a formed on the base 101. The end surface of the shaft portion 104a of the handle 104 is in contact with the side surface 102a of the lower block 102, and the shaft portion 104a becomes a propulsion shaft by turning the handle 104 clockwise (in the direction of arrow Q in the figure). The block 102 can be pressed in the right direction (arrow R direction) in FIG. Here, the pair of blocks 102 and 103 has a wedge-shaped slope having a downward slope as shown in FIG. The block 103 and the ultrasonic motor 10 are constrained in the horizontal direction in FIG. Therefore, the upper block 103 can move upward (in the direction of arrow S) by moving the block 102 in the right direction in FIG. As a result, the entire ultrasonic motor 10 is pressed in the direction of the controlled member 51 so that a desired preload can be applied to each part of the ultrasonic motor 10. After applying the desired preload, the pair of blocks 102 and 103, or the lower block 102 and the base 101 are fixed with screws or the like so that the positions do not shift.

Next, the configuration of the ultrasonic motor 10 will be described in detail.
FIG. 2 is a perspective view illustrating a schematic configuration of the ultrasonic motor according to the present invention. FIG. 3 is a cross-sectional view of the ultrasonic motor according to the present invention.
As illustrated in FIG. 2, the ultrasonic motor 10 includes a movable member 12, a piezoelectric element 14, a support member 16, and a control unit 20.
The support member 16 is formed of a metal material, and has an outer shape that is substantially hexagonal. A substantially hexagonal recess 16c is formed at the center of the support member 16, and an annular shape that surrounds the periphery of the movable member 12 and each piezoelectric element 14 is formed. It is a member.

  Specifically, as shown in FIGS. 2 and 3, the support member 16 has an axis VL as the central axis, the bottom side is formed in a regular hexagonal column shape, and the support member 16 is directed upward from a substantially central portion in the height direction. And has six faces inclined in a hexagonal pyramid shape. A through hole 16a penetrating vertically is formed in the central portion, and an upper side of the through hole 16a is a wide concave portion 16c. Three support portions 16b for supporting the movable member 12 via the piezoelectric elements 14 are formed in the recess 16c. Each support portion 16b has three planes arranged at equal intervals of 120 ° in the circumferential direction with respect to the virtual reference point BP set on the axis VL. Further, each support portion 16b is Each surface is orthogonal to the axis JL of the piezoelectric element 14 having the same predetermined angle θ.

  As shown in FIGS. 2 and 3, three piezoelectric elements 14 are arranged at equal intervals of 120 ° in the circumferential direction with respect to a virtual reference point BP set on the axis VL. Are arranged radially with respect to the virtual reference point BP with a predetermined angle θ equal to each other. Each piezoelectric element 14 has a columnar shape with a rectangular cross section, and each has the same shape and performance. In the ultrasonic motor 10 of the present invention, a predetermined voltage controlled by a control unit 20 described later is applied to the piezoelectric element 14 to cause vibration, and the movable member 12 can be driven by the vibration.

Here, the predetermined angle θ will be described in detail.
As described above, the three piezoelectric elements 14 arranged radially with respect to the virtual reference point BP are arranged with a predetermined angle θ equal to each other in the downward direction of FIG. 3 with respect to the axis VL. The ultrasonic motor 10 can be set according to the design condition of the holding force and the movement amount by the movable member 12 by appropriately changing the predetermined angle θ according to the design condition. Specifically, the predetermined angle θ is preferably 45 degrees. This is because if the predetermined angle is 45 degrees, the holding force and the moving amount by the movable member can be distributed in a well-balanced manner. Therefore, in the present embodiment, the predetermined angle θ is set to 45 degrees.

The movable member 12 obtains a desired driving force by the vibration of each piezoelectric element 14 and relatively moves the controlled member 51 by the driving force.
Specifically, as shown in FIGS. 2 to 3, the movable member 12 is a chip formed in an inverted equilateral triangular frustum shape and having an upper surface formed on a convex spherical surface protruding from the concave portion 16c. Etc. are formed. As shown in FIG. 3, the movable member 12 has three abutments in which each triangular pyramid surface on the side opposite to the controlled member 51 abuts on the end surface 14 a at the other end of the three piezoelectric elements 14. It is set as the surface 12a. That is, each contact surface 12a has an inclination of 45 ° corresponding to the predetermined angle θ (θ = 45 °) that is equal to the axis VL, and is similar to each piezoelectric element 14 on the axis VL. It is formed with an inclined surface having a direction of 120 ° in the circumferential direction with respect to the set virtual reference point BP.

The ultrasonic motor 10 is attached with a pressing force applied by the pressing force applying member described above. The movable member 12, the piezoelectric element 14, and the support portion 16b are bonded and fixed to each other.
Here, the slit 18 is a groove formed in a substantially W shape when viewed from the center portion side of the support member 16, and on the extension line of the axis JL of each piezoelectric element 14, and on one end side of each piezoelectric element 14. It forms in the thick part of the supporting member 16 which opposes, respectively.

  Therefore, by applying a pressing force to the entire ultrasonic motor 10 and the controlled member 51 by a pressing force applying member or the like, each support portion 16b side of the support member 16 is bent with a relatively small elastic deformation at the slit 18 portion. Even if the amount is large, a large preload can be applied to each piezoelectric element 14. Further, since no special member such as a spring is used as the preload adding means, the ultrasonic motor 10 can be configured with a small number of parts.

Next, the control in the control part 20 made to each piezoelectric element 14 and the movable member 12 is demonstrated.
FIG. 4 is an explanatory view showing an image of each piezoelectric element 14 and the movable member 12 controlled by the control unit 20. 2A is a schematic explanatory view of the three piezoelectric elements and the movable member viewed from the T direction in FIG. 2, and FIG. 2B is a cross-sectional view taken along the line U-U in FIG. (C) is explanatory drawing explaining the displacement which arises in the three piezoelectric elements in the figure (a).

  In this ultrasonic motor 10, each of the three piezoelectric elements 14 is provided with an electrode 22 on one side surface of each piezoelectric element 14 having a columnar shape with a rectangular cross section (see FIG. 1), and not shown on the other side surface. The earth electrode is provided. These electrodes 22 are individually provided in an insulated state, and each electrode 22 is connected to the control unit 20. And the drive circuit of the control part 20 of this ultrasonic motor 10 is comprised by the three alternating voltage sources corresponding to each of the three piezoelectric elements 14, and each electrode 22 connected to the three piezoelectric elements 14, respectively. A predetermined voltage V is respectively applied to the piezoelectric element 14 to expand and contract in the longitudinal direction of the rectangular columnar shape of each piezoelectric element 14 (in the direction indicated by the arrow M in FIG. 2), thereby generating a vibration in the longitudinal longitudinal vibration mode. Then, the vibration modes in the three piezoelectric elements 14 are combined to obtain an elliptical motion in a desired direction in the movable member 12, and the controlled member 51 is relatively moved using the elliptical motion in the movable member 12 as a driving force. It is something that can be done.

Specifically, the control unit 20 applies a voltage V whose amplitude and waveform are individually set to the three piezoelectric elements 14 to apply a driving force to the movable member 12 in a desired direction.
That is, as shown in FIG. 4A, the piezoelectric elements 14 </ b> A, 14 </ b> B, 14 </ b> C are arranged in a regular triangular positional relationship with respect to the movable member 12 in the XY plane.

  Now, when a voltage V is applied to the piezoelectric element 14A and the piezoelectric element 14B, the piezoelectric elements 14A and 14B are displaced by D on the axes on which they are installed, as shown in FIG. Here, as described above, each piezoelectric element 14 is formed with a slope corresponding to the predetermined angle θ equal to the axis VL of the movable member 12. If the predetermined angle θ is 45 °, the movable member 12 moves in the Y1 direction in FIG. 4A by the displacement D of the piezoelectric elements 14A and 14B. D · cos 45 ° · sin 30 ° = D / 2 Displace by √2. On the other hand, the piezoelectric element 14C is driven at a voltage V / 2 with a phase of 90 ° with respect to the piezoelectric elements 14A and 14B. As a result, the piezoelectric element 14C is displaced by about D / 2 on the axis of the piezoelectric element 14C, and is displaced by about D / 2√2 in the Y2 direction in FIG. Thereby, if the signal of the voltage V applied to the piezoelectric elements 14A, 14B, and 14C is changed to a continuous sine wave, the movable member 12 forms an elliptical motion on the YZ plane on the convex spherical side. The controlled member 51 can be moved in the Y direction in the XY plane by using the movement.

  When a driving force that can be displaced in another desired direction in the XY plane is applied to the movable member 12, the voltage is applied to each of the piezoelectric elements 14A, 14B, and 14C based on the angle in the desired direction. What is necessary is just to distribute the voltage V to perform. Thus, if the signal of the voltage V is made into a continuous sine wave, the movable member 12 has an elliptical motion on the convex spherical surface side, and a driving force in a desired direction can be obtained in the XY plane. It is done.

Next, the operation and effect of this ultrasonic motor will be described.
As described above, according to the ultrasonic motor 10 according to the present invention, the portion that drives the movable member 12 is configured by the three piezoelectric elements 14, and therefore the control unit 20 corresponding to each piezoelectric element 14 is also configured as follows. A drive circuit can be constituted by three AC voltage sources. Therefore, for example, the configuration and control of each piezoelectric element and the control portion corresponding to each piezoelectric element can be simplified as compared to the above-exemplified ultrasonic motor 200 that can be driven in XY.

Further, according to the ultrasonic motor 10, each piezoelectric element 14 is connected to and supported by the movable member 12, and thus, for example, complicated deformation such as bending hardly occurs in each piezoelectric element 14.
Further, according to the ultrasonic motor 10, since the preload applying means is realized by the slit 18, when applying the preload, each piezoelectric element 14 is larger than the relatively small deflection amount of the support member 16. Each preload can be added. Further, since no special parts are used as the preload addition means, the ultrasonic motor can be configured with a small number of parts.

The ultrasonic motor according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the three piezoelectric elements 14 arranged radially with respect to the virtual reference point BP are arranged at a predetermined angle θ equal to the axis VL at θ = 45 °. The angle θ is not limited to θ = 45 °, and the predetermined angle θ can be appropriately changed according to the design conditions. By appropriately changing the predetermined angle θ according to the design conditions, the holding force and the moving amount by the movable member can be adjusted. Specifically, in order to preferentially configure the holding force of the movable member 12 to the controlled member 51, it is desirable that the predetermined angle θ is narrower than 45 degrees (an acute angle). For example, the predetermined angle θ can be set to 40 °. Further, in order to give priority to the amount of movement by the movable member, it is desirable that the predetermined angle θ be wider than 45 degrees (obtuse angle). For example, the predetermined angle θ can be set to 50 °.

  In the above embodiment, the three piezoelectric elements are arranged at equal intervals of 120 °. However, the present invention is not limited to this, and any arrangement that can drive the movable member is arranged around the virtual reference point BP. It may be arranged at any angle in the direction. For example, in the above-described embodiment, the arrangement interval is set to be equal to 120 °. However, if the two piezoelectric elements are arranged at relative positions of 90 ° (that is, the arrangement angles are 135 °, 135 °, and 90 °). It is suitable for driving in the direction of the orthogonal axis between the X axis and the Y axis in the XY plane.

  Moreover, in the said embodiment, although the part which drives a movable member is comprised by three piezoelectric elements radially arrange | positioned with respect to virtual reference point BP, it is not limited to this, The number of piezoelectric elements is four. There may be more than one. However, in order to simplify the configuration and control of each piezoelectric element and the control portion corresponding to each piezoelectric element, it is desirable to configure a portion that drives the movable member with three piezoelectric elements.

  In the above embodiment, the inner and outer shapes of the support member 16 are each hexagonal. However, the present invention is not limited to this, and the outer shape of the support member 16 is arbitrary. Good. As for the inner shape, any surface can be used as long as the surface can be pressed toward the movable member 12 by the preload applying means for elastically urging each piezoelectric element 14, for example, the slit 18, or the shape corresponding thereto. The shape can be set.

Moreover, in the said embodiment, although the preload addition means is implement | achieved by the slit 18, a preload addition means is not limited to a slit. For example, an elastic member such as a spring may be interposed between the piezoelectric element and the support member. However, when applying a preload, a large output can be obtained for a relatively small amount of deflection, and when configuring an ultrasonic motor without using special parts as a preload adding means, a slit is formed. It is preferable to use preloading means.
In the embodiment, the shape of the slit 18 is W-shaped, but the shape is not limited to this, and may be any shape as long as it can have a spring element.
Moreover, in the said embodiment, although each piezoelectric element 14 uses the same shape and the same performance, it is not limited to this, A thing with a different shape and a different performance can be used.

It is explanatory drawing of the structural example of the XY moving apparatus provided with the pressing force provision member which applies a preload to the ultrasonic motor and the whole to-be-controlled member. It is a perspective view explaining the schematic structure of the ultrasonic motor concerning the present invention. 1 is a front view of an ultrasonic motor according to the present invention, in which the support member is shown in cross section. It is explanatory drawing which shows the image of each piezoelectric element controlled by a control part, and a movable member. It is explanatory drawing which shows an example of the conventional ultrasonic motor. It is explanatory drawing which shows the structural example of the ultrasonic motor which can be made to drive XY conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic motor 12 Movable member 14 Piezoelectric element 16 Support member 18 Slit (preload addition means)
20 Control Unit 22 Electrode 51 Controlled Member 101 Base 102 (Lower) Block 103 (Upper) Block 104 Handle VL Axis Line BP Virtual Reference Point θ Predetermined Angle

Claims (2)

  A support member in which a three-point support portion is formed in a recess formed in the center portion, three piezoelectric elements individually supported by the three-point support portion of the support member, and fixed to the other end of the three piezoelectric elements And a movable member protruding from the recess.   The ultrasonic motor according to claim 1, a relative moving member that relatively moves in contact with the movable member of the ultrasonic motor, and a pressing force that applies a pressing force between the relative moving member and the ultrasonic motor. An XY movement device comprising: an imparting member.

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