JP4819445B2 - Ultrasonic levitation equipment - Google Patents

Description

The present invention relates to an ultrasonic levitation device, and in particular, an ultrasonic vibration generator is composed of a piezoelectric element and is directly joined to a fixed part or a movable part, thereby increasing an allowable load load and making the apparatus compact. It relates to things devised to be able to.

An ultrasonic levitation apparatus using ultrasonic driving is considered to be suitable for clean room environments and precision positioning applications because it is non-contact and free from wear and environmental contamination due to a lubricant. For example, Patent Document 1 discloses such an ultrasonic levitation apparatus.
Incidentally, the said patent document 1 is based on this patent applicant.

WO2004 / 084396A1

  FIG. 9 shows an ultrasonic levitation device disclosed in Patent Document 1. First, there is a fixed portion 201, and this fixed portion 201 includes a fixed-side guide portion 203 having a square shape. The fixed-side guide portion 203 includes a pair of short side portions 205 and 207 and a pair of long side portions 209 and 211. The pair of long side portions 209 and 211 are provided with inclined surfaces 209a and 211a, respectively.

  Ultrasonic vibration generators 213 and 215 are installed inside the fixed guide 203. The ultrasonic vibration generator 213 includes a Langevin type ultrasonic transducer 217 and is held by a holding member 219. Similarly, the ultrasonic vibration generator 215 includes a Langevin type ultrasonic transducer 221 and is held by a holding member 223.

  On the fixed part 201, a movable part 225 is installed in a movable state. The movable portion 225 is formed with inclined surfaces 225a and 225b so as to face the inclined surfaces 209a and 211a on the fixed portion 201 side. A coil base 229 is installed on the base 227, and a coil 231 is installed on the coil base 229. Further, a concave portion 233 is formed on the movable portion 225 side, and a permanent magnet 235 is installed in the concave portion 233. The coil 231 and the permanent magnet 235 constitute a voice coil motor 237.

  According to the above configuration, the movable portion 225 floats with respect to the fixed portion 201 by generating ultrasonic vibrations with the ultrasonic vibration generators 213 and 215. In this state, by passing a current in an appropriate direction through the coil 231, the interaction with the magnetic flux flow of the permanent magnet 235 causes the Y direction relative to the movable portion 225 based on the so-called “Fleming's left hand rule”. A driving force for moving to any one of the above is generated.

The conventional configuration has the following problems.
First, if the vibration amplitude of the guide air bearing surface is increased in order to increase the allowable load load, the vibration is not necessarily excited in the main vibration direction (X direction) but in the other direction, specifically in the Z direction. As a result, other directional vibrations facilitate the contact between the floating surfaces 209a and 211a on the fixed portion 201 side and the floating surfaces 225a and 225b on the movable portion 225 side. As a result, an increase in the allowable load load is hindered. There was a problem that.
This point will be described in detail. In the conventional case, the ultrasonic vibration generators 213 and 215 are composed of the Langevin type ultrasonic transducers 217 and 221, and correspond to the nodes of the Langevin type ultrasonic transducers 217 and 221. In the central portion, the whole is held by holding members 219 and 223. That is, the space between the holding members 219 and 223 and the connecting portion between the short side portions 205 and 207 of the fixed portion side guide portion 203 is in a cantilever state. That is, the vibration in the Z direction perpendicular to the main vibration direction (X direction) is likely to be excited. In particular, when the load is increased, the vibration is more likely to be excited.
If an attempt is made to increase the vibration amplitude in the main vibration direction (X direction) in order to increase the allowable load, vibration in the vertical direction (Z direction) can be easily excited. The floating surfaces 209a and 211a on the side and the floating surfaces 225a and 225b on the movable part 225 side are easily contacted, and as a result, an increase in the allowable load load is hindered.
Further, if the size of the ultrasonic vibration generators 213 and 215 is increased in order to increase the vibration power, the enlarged ultrasonic vibration generators 213 and 215 are made compact inside the mouthpiece-shaped fixed portion side guide 203. There was a problem that it could not be placed.

The present invention has been made based on such points, and an object thereof is to provide an ultrasonic levitation apparatus capable of increasing the allowable load and reducing the size of the apparatus.

In order to achieve the above object, an ultrasonic levitation apparatus according to claim 1 of the present invention comprises a fixed part comprising a pair of long side parts and a pair of short side parts in a square shape, and the fixed part. Provided so that it can be joined directly to both sides or one side of the side of the short side, or to be joined directly to both sides or one side of the top and bottom of the short side. comprising a piezoelectric element which is a, the piezoelectric element is a single-plate piezoelectric element or piezoelectric device, and characterized by being constituted such that the movable unit is floated by the piezoelectric element is vibrated ultrasonically To do.

As described above, the ultrasonic levitation apparatus according to the present invention includes a fixed part, a movable part installed movably with respect to the fixed part, and an ultrasonic vibration generator provided in the fixed part or the movable part. In the ultrasonic levitation apparatus configured to float the movable part by ultrasonic vibration of the ultrasonic vibration generation apparatus, the ultrasonic vibration generation apparatus includes a piezoelectric element, and the piezoelectric The element is configured to be directly joined to the fixed part or the movable part. In the case of this type of piezoelectric element, vibrations in the direction perpendicular to the main vibration direction are hardly excited, and therefore the air bearing surface on the fixed part side and the air bearing surface on the movable part side are caused by vibrations in other directions. without concern that come into contact, it is possible to increase the permissible applied load effectively.
In addition, since the ultrasonic vibration generator is composed of a thin plate-like piezoelectric element, the entire ultrasonic levitation apparatus as well as the ultrasonic vibration generator itself can be simplified and made compact.
Moreover, energy transmission efficiency loss can be reduced by directly joining the piezoelectric element to the fixed part or the movable part. In addition, the effective space on the fixed part side is expanded.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, there is a fixed portion 1, and the fixed portion 1 includes a fixed-side guide portion 3 having a square shape. The fixed-side guide portion 3 includes a pair of short side portions 5 and 7 and a pair of long side portions 9 and 11. The pair of long side portions 9 and 11 are provided with inclined surfaces 9a and 11a, respectively.

  Piezoelectric elements 13 and 15 as ultrasonic vibration generators are directly joined and arranged on both side surfaces of the pair of short sides 5 and 7 of the fixed side guide 3. The piezoelectric elements 13 and 15 are electrodes that are provided with electrodes on both sides of a plate-like piezoelectric material so that an alternating voltage can be applied, and are of a single plate type constituted by a single plate. Support members 17 and 19 are installed at both ends in the longitudinal direction of the fixed portion 1, and the fixed portion 1 is supported on the base 21 via the support members 17 and 19.

  On the fixed part 1, a movable part 25 is installed in a movable state. The movable portion 25 is formed with inclined surfaces 25a and 25b so as to face the inclined surfaces 9a and 11a on the fixed portion 1 side.

A coil base 29 is installed on the base 21, and a coil 31 is installed on the coil base 29. Further, a concave portion 33 is formed on the movable portion 25 side, and a permanent magnet 35 is installed in the concave portion 33. The coil 31 and the permanent magnet 35 constitute a voice coil motor 37.

  According to the above configuration, the movable portion 25 floats with respect to the fixed portion 1 by generating ultrasonic vibrations with the piezoelectric elements 13 and 15. In this state, by passing a current in an appropriate direction through the coil 31, the interaction with the magnetic flux flow of the permanent magnet 35 causes the Y direction relative to the movable portion 25 based on the so-called “Fleming's left-hand rule”. A driving force for moving to any one of the above is generated.

As described above, according to the present embodiment, the following effects can be obtained.
First, piezoelectric elements 13 and 15 are used as an ultrasonic vibration generating device. Since these types of piezoelectric elements 13 and 15 are thin plate-like, the main vibration direction (X direction) is applied by applying an AC voltage. ), The short sides 5 and 7 can be expanded and compressed in the X direction. At this time, vibration in the direction (Z direction) orthogonal to the main vibration direction (X direction) is almost excited as in the prior art. It will never be done. Thus, other direction of the fixed part 1 side of the air bearing surface 9a by the vibration, the air bearing surface 25a of 11a and the movable portion 25 side, there is no concern that 25b and is come into contact, effectively increase the permissible applied load Can be planned.
In addition, since the ultrasonic vibration generating device is constituted by the thin plate-like piezoelectric elements 13 and 15, not only the ultrasonic vibration generating device itself but also the entire ultrasonic levitation device can be simplified and made compact.
In the case of this embodiment, the support members 17 and 19 are attached to the central portions of the short sides 5 and 7, thereby providing a stable support structure. That is, the central part of the short sides 5 and 7 is in the vicinity of the vibration node and is difficult to cause vibration attenuation.
In addition, since the piezoelectric elements 13 and 15 are directly joined to the short sides 5 and 7, energy transmission loss can be reduced.
Moreover, since the effective space inside the fixed side guide part 3 is expanded, the drive device, that is, the coil 31, the permanent magnet 35, etc. can be easily installed inside the fixed side guide part 3.
In the case of the present embodiment, since the piezoelectric elements 13 and 15 are joined and arranged on both side surfaces of the short sides 5 and 7, a higher vibration amplitude can be obtained, thereby allowing an allowable load. It is possible to increase the load more effectively.
In addition, the structure which attaches a piezoelectric element only to either of the both sides | surfaces of the short side parts 5 and 7 is also considered.
Further, by driving the piezoelectric elements of the short side portions 5 and 7 with a phase difference, a traveling wave can be generated in the fixed side guide portion 3, and the movable portion 25 can be driven by the traveling wave. it can. In that case, a driving device including the coil 31, the permanent magnet 35, and the like is not necessary, and the configuration can be simplified.

Next, a second embodiment of the present invention will be described with reference to FIG. In the case of the second embodiment, as shown in FIG. 6A, the piezoelectric element 13 is joined and arranged on the bottom surface of the short side portion 5.
Although not shown, the same piezoelectric element 13 is joined and arranged on the bottom surface of the short side 7 on the opposite side.
Other configurations are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and description thereof is omitted.
With such a configuration, substantially the same effect can be achieved.
In this case, a configuration in which a piezoelectric element is also bonded to the upper surfaces of the short sides 5 and 7 is conceivable. A configuration in which the piezoelectric element is bonded only to the upper surfaces of the short sides 5 and 7 is also conceivable.

Next, a third embodiment of the present invention will be described with reference to FIG. In the case of the third embodiment, the short side part 5 having the same shape is installed below the short side part 5, and the short side parts 5, 5 are arranged.
The piezoelectric element 13 is sandwiched between the two.
Although not shown in the figure, a similar short side portion 7 is also provided below the short side portion 7 on the opposite side, and the piezoelectric element 13 is sandwiched between the short side portions 7 and 7. It is what.
Other configurations are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and description thereof is omitted.
With such a configuration, substantially the same effect can be achieved. In addition, a floating guide surface can be provided on the lower side.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the case of the fourth embodiment, the shape of the short side portion 5 is vertically symmetrical, and the piezoelectric elements 13 are attached to the upper and lower ends of the short side portion 5.
Other configurations are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and description thereof is omitted.
With such a configuration, substantially the same effect can be achieved. In addition, a floating guide surface can be provided on the lower side.

The present invention is not limited to the first to fourth embodiments.
First, in the first to third embodiments, a piezoelectric element is provided with electrodes on both sides of a plate-like piezoelectric material so that an alternating voltage can be applied, and is configured by a single plate. However, the present invention is not limited to this. For example, when a large vibration amplitude is obtained, it is necessary to apply a high voltage, but it is conceivable to use a laminated piezoelectric element in which a large number of thin piezoelectric elements are laminated in order to reduce the voltage.
Moreover, in the said 1st-3rd embodiment, although the example which attached the vibration generator to the fixed part was shown, you may make it attach to the movable part side.

The present invention relates to an ultrasonic levitation device, and more particularly, to a device devised so that an allowable load can be increased and the device can be made compact by improving the configuration of an ultrasonic vibration generator, for example, uniaxial Suitable for actuator.

It is a figure which shows the 1st Embodiment of this invention and is a top view which shows the structure of an ultrasonic levitation apparatus. It is a figure which shows the 1st Embodiment of this invention and is a front view which shows the structure of an ultrasonic levitation apparatus. It is a figure which shows the 1st Embodiment of this invention and is a side view which shows the structure of an ultrasonic levitation apparatus. It is a figure which shows the 1st Embodiment of this invention, and is IV-IV sectional drawing of FIG. 5A and 5B are views showing a first embodiment of the present invention, in which FIG. 5A is a side view of a fixing part of the ultrasonic levitation apparatus, and FIG. 5B is a partial plan view of the fixing part of the ultrasonic levitation apparatus. is there. 6A and 6B are views showing a second embodiment of the present invention, in which FIG. 6A is a side view of a fixing portion of the ultrasonic levitation device, and FIG. 6B is a partial plan view of the fixing portion of the ultrasonic levitation device. is there. 7A and 7B are views showing a third embodiment of the present invention, in which FIG. 7A is a side view of a fixing portion of the ultrasonic levitation apparatus, and FIG. 7B is a partial plan view of the fixing portion of the ultrasonic levitation apparatus. is there. FIG. 8A is a side view of a fixing unit of an ultrasonic levitation apparatus, and FIG. 8B is a partial plan view of the fixing unit of an ultrasonic levitation apparatus, showing a fourth embodiment of the present invention. is there. FIG. 9A is a plan view showing the configuration of the ultrasonic levitation apparatus, FIG. 9B is a view taken along the line bb of FIG. 9A, and FIG. It is cc sectional drawing of 9 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed part 3 Fixed part side guide part 5 Short side part 7 Short side part 9 Long side part 11 Long side part 13 Piezoelectric element 15 Piezoelectric element 25 Movable part

Claims (1)

A fixed portion comprising a pair of long sides and a pair of short sides and having a square shape ;
A movable part installed movably with respect to the fixed part;
A piezoelectric element provided to be directly bonded to both sides or one side of the side surface of the short side part, or provided to be directly bonded to both sides or one side of the upper and lower surfaces of the short side part , and
The piezoelectric element is a single plate piezoelectric element or a laminated piezoelectric element ,
An ultrasonic levitation apparatus, wherein the movable part is floated by ultrasonic vibration of the piezoelectric element .

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