JP2010122403A - Fine-positioning mechanism equipped with ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve stable drive by suppressing resonance vibration as well as suppressing deformation of a driven part. <P>SOLUTION: A fine-positioning mechanism equipped with an ultrasonic motor includes: a fixed base 1; a moving body 3 supported so as to be movable in the direction of a moving axis relative to the fixed base 1; a slide member 6 disposed on one face of the moving body 3; a vibrating body 8 that includes a three-dimensional shape and excites a plurality of vibration modes by the application of a high frequency voltage signal; a holding mechanism 7 holding the vibrating body 8 relative to the fixed base 1 and pressing the vibrating body against the moving body 3; a driver 9 disposed on the vibrating body 8 and in frictional contact with the sliding member 6. A part (pressing member 4) of the moving body 3 is configured as a separate body, and the sliding member 6 is provided on one face of the part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fine movement mechanism provided with an ultrasonic motor.

  Microscopes are often used to observe fine structures such as semiconductors and biological samples. In the microscope used for such observation, an XY stage is used to position an arbitrary position of the observation target under the microscope observation, and the feeding resolution equal to or better than the microstructure to be observed and the stability at rest Is required. In many cases, it is necessary to observe a plurality of observation positions with high throughput, and high-speed operation is also required.

  Ultrasonic motors are attracting attention as one of actuators that meet such needs. For example, Patent Document 1 proposes an apparatus that employs an ultrasonic motor as an actuator for an XY stage for a microscope.

  As an example of an ultrasonic motor used in such a stage, there is a linear drive type ultrasonic actuator using a rectangular parallelepiped shape. Most of such ultrasonic motors are composed of a laminated piezoelectric material, and have a bending vibration electrode and a longitudinal vibration electrode inside, and a sine wave signal whose phase is shifted by 90 ° is applied to each electrode. To drive.

FIG. 8 is a diagram schematically showing an example of a stage moving mechanism provided with such a linear drive type ultrasonic actuator.
In the example shown in the figure, an ultrasonic vibrator (hereinafter simply referred to as “vibrator”) made of a laminated piezoelectric material having a bending vibration electrode 101 (101a, 101b, 101c, 101d) and a longitudinal vibration electrode 102. In an ultrasonic motor 105 having 103 and two driver elements 104 (104a, 104b), a longitudinal vibration signal which is a sine wave signal is applied to the longitudinal vibration electrode 102, and the longitudinal vibration signal is applied to the bending vibration electrode 101. When a bending vibration signal that is a sine wave signal having a phase difference of 90 ° is applied, the movable body (stage) 107 moves along the guide 106.

  In the figure, the sign “+” or “−” of the bending vibration electrode 101 and the longitudinal vibration electrode 102 indicates the polarization direction of the piezoelectric body. For example, when a positive voltage is applied to the electrode, the piezoelectric body of the “+” sign electrode portion is deformed to extend in the longitudinal direction, and the piezoelectric body of the “−” sign electrode portion is shrunk in the longitudinal direction. Deform. Therefore, when a sinusoidal signal is applied to the bending vibration electrode 101, bending deformation vibration as schematically shown in FIG. 9A is excited, and when a sinusoidal signal is applied to the longitudinal vibration electrode 102. Longitudinal vibration extending and contracting in the longitudinal direction as schematically shown in FIG. In FIGS. 4A and 4B, dotted arrows indicate the deformation direction of the piezoelectric body, and solid arrows indicate the movement direction of the driver element 104. In this way, when the two types of vibration phases are shifted by 90 ° and excited simultaneously, the driver element 104 vibrates so as to draw an elliptical locus (see the dotted line in FIG. 8) as shown by the arrow in FIG. At this time, the frictional force is reduced by the vertical component of the force generated when the driver element 104 contacts the movable member 107, and the movable member 107 is moved by the force of the horizontal component.

  By the way, when the ultrasonic motor is driven and vibrated in this way, the movable body is excited. Here, if the natural frequency of the movable body is present in the vicinity of the driving frequency of the ultrasonic motor, the movable body will resonate and generate large vibrations, so that the driving efficiency is significantly reduced. In this case, the higher the Young's modulus is made of an integral part and the higher the Young's modulus, the larger the amplitude of resonance, and the lower the drive efficiency becomes.

Therefore, Patent Document 2 proposes a method for reducing such vibration generation.
JP 2008-187768 A JP 2000-324865 A

  However, in the method described in Patent Document 2, since the vibration absorbing member used for removing unnecessary vibration generally has low rigidity, the driven body is deformed by the pressing force of the ultrasonic motor and is in a contact state. Changes are likely to occur. Such a change in the contact state causes a decrease in driving efficiency. In particular, in the case of an ultrasonic motor that requires a large driving force, such as a microscope stage, a large pressing force is required, so that a driven body that receives the pressing force of the ultrasonic motor is required to have high rigidity.

  In view of the above circumstances, an object of the present invention is to provide a fine movement mechanism including an ultrasonic motor that suppresses resonance vibration while suppressing deformation of a driven body and enables stable driving.

  In order to achieve the above object, an apparatus according to a first aspect of the present invention is a fine movement mechanism provided with an ultrasonic motor, and is supported by a fixed base and movable relative to the fixed base in a movement axis direction. A moving body, a sliding member provided on one surface of the moving body, a three-dimensional vibration body that excites a plurality of vibration modes by applying a high-frequency voltage signal, and the vibration body is fixed to the fixed base. A holding mechanism that is held against the moving body and pressed against the moving body, and a driving element that is provided on the vibrating body and frictionally contacts the sliding member, and the moving body is partially configured as a separate body, The sliding member is provided on one surface of the part.

  In the apparatus according to the second aspect of the present invention, in the first aspect, the moving body is configured such that the part is fixed so as to be in close contact with two or more planes. It is characterized by.

An apparatus according to a third aspect of the present invention is characterized in that, in the first or second aspect, a part of the moving body includes a vibration damping material.
The apparatus according to a fourth aspect of the present invention is the apparatus according to the first or second aspect, wherein a part of the moving body is formed by laminating a plurality of metal materials in a direction perpendicular to a pressing direction by the holding mechanism. It is constituted by that.

  The device according to a fifth aspect of the present invention is the apparatus according to the first or second aspect, wherein a part of the moving body has a metal material and a vibration damping material in a direction perpendicular to a pressing direction by the holding mechanism. And are alternately laminated.

  An apparatus according to a sixth aspect of the present invention is characterized in that, in the fourth or fifth aspect, a part of the moving body includes two or more kinds of metal materials.

  According to the present invention, it is possible to suppress resonance vibration while suppressing deformation of the driven body, to enable stable driving, and to improve driving efficiency.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a perspective view schematically showing a fine movement mechanism provided with an ultrasonic motor according to the first embodiment of the present invention. FIG. 2A is a partial top view of the fine movement mechanism according to this embodiment, and FIG. 2B is a cross-sectional view taken along the line AA ′ shown in FIG. FIG. 3 is a cross-sectional view of the plunger. 4 is a cross-sectional view in the XZ plane of the fine movement mechanism according to the present embodiment shown in FIG.

  As shown in FIG. 1, a movable body 3 supported by a guide 2 (2a, 2b) so as to be movable in one axial direction, which is a moving axis direction, is held on the fixed base 1. ing. The guide 2 is a guide such as a linear ball guide.

A part of the moving body 3 is configured as a separate body. In the following description, a part thereof will be referred to as a pressing member 4 and the remaining part will be referred to as a moving body 3.
The pressing member 4 is fixed to the moving body 3 by five fixing screws 5 (5a, 5b, 5c, 5d, 5e) so as to come into contact with the moving body 3 on two surfaces. In this embodiment, the pressing member 4 is made of a highly rigid metal material such as aluminum. One of the surfaces of the pressing member 4 that is not in contact with the moving body 2 is provided with a sliding member 6 made of a hard material such as ceramic that is resistant to frictional sliding. The sliding member 6 may be a coating material that is resistant to frictional sliding formed by surface treatment or the like.

  A vibration body 8 having a three-dimensional shape is bonded and fixed to the holding mechanism 7, and a driver element 9 (9 a, 9 b) is bonded and fixed to the vibration body 8. Further, the holding mechanism 7 is fixed to the fixing base 1 by two fixing screws 10 (10a, 10b) so that the driver 9 is in contact with the sliding member 6.

Here, the holding mechanism 7 will be described in more detail with reference to FIGS. 2 (a), (b) and FIG.
The holding mechanism 7 is made of a metal material such as aluminum, for example. Specifically, as shown in FIG. 2 (a), the thin plate spring portion 12 (formed by providing a notch hole portion 11 by wire electric discharge machining or the like. In FIG. 5A, there is a hatched portion. A thick portion 12a that does not act as a spring is formed at the center of the thin plate spring portion 12, and the thick portion 12a and the vibrating body 8 are bonded to each other with a high strength adhesive such as epoxy or ceramic adhesive. Yes. At this time, the thin plate spring portion 12 and the vibrating body 8 are configured to be provided close to each other in parallel. Further, the bonding position of the vibrating body 8 is near the center of the bonding surface of the vibrating body 8.

  In the vibrating body 8, two driver elements 9 (9a, 9b) are provided on the surface opposite to the surface to which the thick portion 12a of the holding mechanism 7 is bonded. The driver element 9 is formed of a material whose base material is a resin having a relatively small friction coefficient, such as polyacetal or ceramic containing reinforcing fibers. The holding mechanism 7 is fixed to the fixing base 1 by two fixing screws 10 (10a, 10b) through two fixing screw holes 13 (13a, 13b) in a state where both of the driver elements 9 are in contact with the sliding member 6. Is done. At this time, it is desirable that the pressing force to the moving body 3 side is in the vicinity of zero with almost no deflection of the thin leaf spring portion 7.

  Further, the holding mechanism 7 is formed with a female screw. Specifically, as shown in FIG. 2 (b), the thick portion 12a can be pressed by screwing a plunger 14 having a male screw formed on the outer periphery. ing. As shown in detail in FIG. 3, a coil spring 15 is built in the plunger 14, and a pressing force is generated when the tip member 16 is pushed. For this reason, a pressing force corresponding to the amount of movement of the tip member 16 of the plunger 14 (ΔW in the figure) is applied to the thick portion 12a. At this time, the vibrating body 8 is also pressed against the sliding member 6 together with the driver element 9. The spring constant of the coil spring 15 of the plunger 14 is configured to be smaller than the pressing direction spring constant of the thin plate spring portion 12. For this reason, the plunger 14 enables finer adjustment of the pressing force.

  In the fine movement mechanism according to the present embodiment, the vibrating body 8 has the same configuration as that of the vibrator 103 shown in FIG. 8, for example, and a predetermined high-frequency voltage signal (for example, the above-described) 8 and 9 (a) and 9 (b) are applied), it is possible to excite a plurality of vibration modes. Then, by exciting the vibration body 8 with a plurality of vibration modes, the movable body 3 fixed to the pressing member 4 is moved together with the sliding member 4 in contact with the driver 9 provided on the vibration body 8. It is possible to make it.

In the fine movement mechanism according to the present embodiment, the ultrasonic motor includes at least the vibrating body 8 and the driver element 9.
In the fine movement mechanism according to this embodiment configured as described above, the pressing force by the plunger 14 is transmitted through the thick portion 12a, the vibrator 8, the driver 9, and the sliding member 4 as shown in FIG. And is received by the pressing member 4. In this case, the pressing member 4 is a metal material having high rigidity as described above, and the pressing direction is in contact with the moving body 3 so as to be in close contact with the surface, so that the pressing force can be received with high rigidity.

  Further, when resonance vibration is generated in the pressing member 4 when a driving signal is applied to the vibrating body 8, vibration energy is consumed by friction of the contact surface between the pressing member 4 and the moving body 3, and the amplitude of the resonance vibration. Can be attenuated. In this case, the larger the contact area, the greater the damping of vibration. Therefore, as in this embodiment, two surfaces that are the contact surfaces of the moving body 3 and the pressing member 4, that is, the fastening surface of the fixing screw 5 and the pressing surface. Since vibration energy is consumed on the two contact surfaces in the direction, the vibration damping effect can be enhanced. Thus, the vibration amplitude becomes smaller due to attenuation, so that the contact state between the driver 9 and the sliding member 6 is stabilized, and the driving efficiency can be improved.

  As described above, in the fine movement mechanism according to the present embodiment, since the rigidity with respect to the pressing force to the pressing member 4 is high, unnecessary deformation does not occur, and the vibration excited by the pressing member 4 Since friction is attenuated at the contact surface, driving efficiency can be improved.

In the fine movement mechanism according to the present embodiment, the moving body 3 and the pressing member 4 can be formed using the same metal material such as aluminum, but can also be formed using different metal materials. Further, by configuring the fixed base 1, the moving body 3, the pressing member 4, and the holding mechanism 7 using the same metal material such as aluminum, there is no adverse effect due to temperature change (deformation due to the bimetal effect, etc.), and thermal It is also possible to adopt a configuration that is advantageous for obtaining stable stability.
<Second Embodiment>
FIG. 5 is a cross-sectional view of a fine movement mechanism equipped with an ultrasonic motor according to the second embodiment of the present invention. In addition, the figure is a figure corresponding to sectional drawing (FIG. 4) in XZ plane of the fine movement mechanism which concerns on 1st Embodiment shown in FIG.

  The fine movement mechanism according to this embodiment is different from the fine movement mechanism according to the first embodiment only in the configuration of the pressing member 4. That is, in the fine movement mechanism according to the present embodiment, as shown in FIG. 5, in the pressing member 4, the pressing direction to the pressing member 4 and the central portion of the surface that is in close contact with the moving body 3. A vibration absorbing member (also referred to as a vibration damping material) 4a is provided. The vibration absorbing member 4a is a viscous material such as rubber or gel for attenuating the amplitude of resonance vibration generated in the pressing member 4.

  With such a configuration, since the moving body 4 and the metal surface of the pressing member 4 on the side where the vibration absorbing member 4a is provided are in close contact with each other, the pressing force on the pressing member 4 is received with high rigidity. be able to.

  Further, when resonance vibration occurs in the pressing member 4 when a drive signal is applied to the vibrating body 8, it is caused by friction on the contact surface between the moving body 3 and the pressing member 4 described in the description of the first embodiment. In addition, the amplitude of the resonance vibration can be attenuated by the vibration absorbing member 4a. As the amplitude of the resonance vibration is attenuated in this way, the contact state between the driver 9 and the sliding member 6 is stabilized, and the driving efficiency can be improved.

As described above, even in the fine movement mechanism according to the present embodiment, unnecessary deformation does not occur because the rigidity against the pressing force to the pressing member 4 is high, and vibration excited by the pressing member 4 is Since it is attenuated by friction at the contact surface and also attenuated by the vibration absorbing member 4a, driving efficiency can be improved.
<Third Embodiment>
FIG. 6 is a cross-sectional view of a fine movement mechanism provided with an ultrasonic motor according to the third embodiment of the present invention. This figure also corresponds to the cross-sectional view (FIG. 4) in the XZ plane of the fine movement mechanism according to the first embodiment shown in FIG.

  The fine movement mechanism according to this embodiment is also different from the fine movement mechanism according to the first embodiment only in the configuration of the pressing member 4. That is, in the fine movement mechanism according to the present embodiment, as shown in FIG. 6, the Young's modulus is different in the direction in which the pressing member 4 is perpendicular to the pressing direction to the pressing member 4 (vertical direction in the figure) 2. It is constructed by laminating various kinds of metals alternately. Here, as the pressing member 4, a layer 4b made of a first metal material (for example, the same metal material as the pressing member 4 according to the first embodiment) is sandwiched between layers 4c made of a second metal material. A pressing member having a three-layer structure is shown. Moreover, the thickness of each layer is the same.

  With such a configuration, the metal of each layer constituting the pressing member 4 has a highly rigid pressing force to the pressing member 4 because the direction in which the cross-sectional secondary moment increases and the pressing direction to the pressing member 4 coincide. You can catch it. Further, it is possible to make it difficult to cause unnecessary deformation of the pressing member 4.

  Further, when resonance vibration occurs in the pressing member 4 when a drive signal is applied to the vibrating body 8, it is caused by friction on the contact surface between the moving body 3 and the pressing member 4 described in the description of the first embodiment. In addition, the amplitude of the resonance vibration can be attenuated by the friction on the laminated surface of each layer of the pressing member 4 by laminating two kinds of metals having different Young's moduli. As the amplitude of the resonance vibration is attenuated in this way, the contact state between the driver 9 and the sliding member 6 is stabilized, and the driving efficiency can be improved.

  As described above, even in the fine movement mechanism according to the present embodiment, unnecessary deformation does not occur because the rigidity against the pressing force to the pressing member 4 is high, and vibration excited by the pressing member 4 is Since frictional damping is performed on the contact surface and the laminated surface of the pressing member 4, driving efficiency can be improved.

In the pressing member 4 according to the present embodiment, the number of stacked layers is not limited to three, and may be a plurality of other stacked numbers. Further, the number of types of metals having different Young's moduli is not limited to two, and may be three or more. Furthermore, the stacking order is not limited to the above-described stacking order, and other stacking orders may be used. In addition, the thickness of each layer is not limited to the same, and may be different, or only some of the plurality of layers may have the same or different thickness.
<Fourth Embodiment>
FIG. 7 is a cross-sectional view of a fine movement mechanism provided with an ultrasonic motor according to the fourth embodiment of the present invention. This figure also corresponds to the cross-sectional view (FIG. 4) in the XZ plane of the fine movement mechanism according to the first embodiment shown in FIG.

The fine movement mechanism according to this embodiment is also different from the fine movement mechanism according to the first embodiment only in the configuration of the pressing member 4. That is, in the fine movement mechanism according to the present embodiment, as shown in FIG. 7, the pressing member 4 uses the two kinds of metals having different Young's moduli and the vibration absorbing member, so that the pressing member 4 is pressed against the pressing member 4. The metal and the vibration absorbing member are alternately laminated in a vertical direction (vertical direction in the figure). Here, as the pressing member 4, the layer 4b made of the first metal material (for example, the same metal material as the pressing member 4 according to the first embodiment) is used as the vibration absorbing member (for example, the pressing according to the second embodiment). A pressing member having a five-layer structure is shown in which the member 4 is sandwiched between layers 4d of members of the same material as the vibration absorbing member 4a) and further sandwiched between layers 4c made of a second metal material. Moreover, the thickness of each layer is the same.

  With such a configuration, the metal of each layer constituting the pressing member 4 matches the direction in which the cross-sectional secondary moment increases and the pressing direction to the pressing member 4, and the pressing member 4 moves to the pressing member 4. Therefore, the pressing force applied to the pressing member 4 can be received with high rigidity. Further, it is possible to make it difficult to cause unnecessary deformation of the pressing member 4.

  Further, when resonance vibration occurs in the pressing member 4 when a drive signal is applied to the vibrating body 8, it is caused by friction on the contact surface between the moving body 3 and the pressing member 4 described in the description of the first embodiment. In addition, the amplitude of the resonance vibration can be attenuated by the friction and vibration absorbing member on the layered surface of each layer of the pressing member 4 formed by laminating two kinds of metals having different Young's modulus and the vibration absorbing member. As the amplitude of the resonance vibration is attenuated in this way, the contact state between the driver 9 and the sliding member 6 is stabilized, and the driving efficiency can be improved.

  As described above, even in the fine movement mechanism according to the present embodiment, unnecessary deformation does not occur because the rigidity against the pressing force to the pressing member 4 is high, and vibration excited by the pressing member 4 is Since the frictional damping is performed on the contact surface and the laminated surface of the pressing member 4 and the vibration absorbing member is used, the driving efficiency can be improved.

  Note that in the pressing member 4 according to the present embodiment, the number of stacked layers is not limited to five, and may be a plurality of other stacked numbers. However, it is desirable that at least the uppermost layer (the layer forming the fastening surface of the fixing screw 5) be a layer of a metal material. Further, the number of types of metals having different Young's moduli is not limited to two, and may be three or more. Furthermore, the stacking order is not limited to the above-described stacking order, and other stacking orders may be used. In addition, the thickness of each layer is not limited to the same, and may be different, or only some of the plurality of layers may have the same or different thickness.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and it is needless to say that various improvements and changes may be made without departing from the gist of the present invention.

It is a perspective view which shows typically the fine movement mechanism provided with the ultrasonic motor based on 1st Embodiment. (a) is a partial top view of the fine movement mechanism according to the first embodiment, and (b) is a cross-sectional view taken along line AA ′ shown in FIG. It is sectional drawing of a plunger. It is sectional drawing in the XZ plane of the fine movement mechanism shown in FIG. It is sectional drawing of the fine movement mechanism provided with the ultrasonic motor based on 2nd Embodiment. It is sectional drawing of the fine movement mechanism provided with the ultrasonic motor based on 3rd Embodiment. It is sectional drawing of the fine movement mechanism provided with the ultrasonic motor based on 4th Embodiment. It is a figure which shows typically an example of the stage moving mechanism provided with the linear drive type ultrasonic actuator. (a) is a diagram schematically showing a state when bending deformation vibration is excited, and (b) is a diagram schematically showing a state when longitudinal vibration is excited.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing base 2 Guide 3 Moving body 4 Pressing member 5 Fixing screw 6 Sliding member 7 Holding mechanism 8 Vibrating body 9 Driver 10 Fixing screw 11 Notch hole part 12 Thin plate spring part 13 Fixing screw hole 14 Plunger 15 Coil spring 16 Tip member 101 Electrode for bending vibration 102 Electrode for longitudinal vibration 103 Ultrasonic vibrator 104 Driver element 105 Ultrasonic motor 106 Guide 107 Movable body

Claims (6)

A fine movement mechanism equipped with an ultrasonic motor,
A fixed base;
A movable body supported so as to be movable in the movement axis direction with respect to the fixed base;
A sliding member provided on one surface of the moving body;
A vibrating body having a three-dimensional shape and exciting a plurality of vibration modes by application of a high-frequency voltage signal;
A holding mechanism that holds the vibrating body against the fixed base and presses the moving body;
A driver provided in the vibrating body and in frictional contact with the sliding member;
With
A part of the moving body is configured as a separate body, and the sliding member is provided on one surface of the part.
A fine movement mechanism characterized by that. The moving body is configured by being fixed so that the part is in close contact with two or more planes.
The fine movement mechanism according to claim 1. A portion of the moving body includes a vibration damping material;
The fine movement mechanism according to claim 1 or 2, characterized by the above. A part of the moving body is configured by laminating a plurality of metal materials in a direction perpendicular to a pressing direction by the holding mechanism.
The fine movement mechanism according to claim 1 or 2, wherein A part of the moving body is configured by alternately laminating metal materials and vibration damping materials in a direction perpendicular to the pressing direction by the holding mechanism.
The fine movement mechanism according to claim 1 or 2, wherein A part of the moving body includes two or more kinds of metal materials,
The fine movement mechanism according to claim 4 or 5, wherein