JP4535709B2 - Drive device - Google Patents

Description

  The present invention relates to a drive device using an ultrasonic motor.

  Ultrasonic motors have the features that the minimum amplitude is as small as nanometer order, positioning with high resolution is possible, and the driving force is large because of frictional drive. Practical application to a rotational motion system such as a vibration alarm has been carried out, and recently, application to a linear motion system drive device such as a precision processing machine, a precision measurement device, and a semiconductor manufacturing device has been attempted.

  FIG. 5 shows a conventional drive device 10 which is one example of application to a linear motion system drive device. This apparatus is provided with a pair of guide members 12 such as cross roller guides on a base board 11 and linearly guides a stage 13 as a movable body by these guide members 12.

  A driving force transmission member 14 is installed on one side surface of the stage 13 in parallel with the guide member 12, and a linear scale 15 is installed on the other side surface of the stage 13 in parallel with the driving force transmission member 14. A measuring head 16 is provided at a position facing the linear scale 15 to form a position detecting means 17, and an ultrasonic motor 20 is installed at a position facing the driving force transmitting member 14, The friction member 25 of the ultrasonic motor 20 is in contact with the contact surface of the driving force transmission member 14 perpendicularly.

In the figure, reference numeral 26 denotes a case for housing the ultrasonic motor 20, reference numeral 27 denotes a spring for holding the ultrasonic motor 20 in the case 26 without obstructing the driving of the ultrasonic motor 20, and reference numeral 28 denotes a drive for the stage 13. A spring for pressing the force transmission member 14.
Reference numeral 18 denotes a drive control unit for controlling the drive speed of the stage 13 based on the position information obtained from the position detection means 17. The drive command signal output from the drive control unit 18 is input to the driver 19. Then, the ultrasonic motor 20 is driven by the drive voltage output from the driver 19.

  The friction member 25 and the driving force transmission member 14 are made of general ceramics such as alumina, glass or the like, and the friction member 25 made of ceramics or glass and the driving force transmission member 14 are brought into contact with each other. The stage 13 is driven by the friction drive.

  Further, as shown in FIGS. 6A and 6B, the structure of the ultrasonic motor 20 used in the driving device 10 of FIG. 5 is divided into four on one main surface of the piezoelectric ceramic plate 21. The electrode films 22a, 22b, 22c, and 22d are connected to connect the electrode film 22a and the electrode film 22d located diagonally, and connect the electrode film 22b and the electrode film 22c located diagonally to each other, and The main surface is composed of a vibrating body 24 having an electrode 23 formed on almost the entire surface, and a friction member 25 made of ceramics or glass provided on an end surface of the piezoelectric ceramic plate 21, and formed on the one main surface. By grounding the electrode film 23 and applying voltages having different phases to the electrode film 22a and the electrode film 22b formed on the other main surface, longitudinal vibration and lateral vibration are generated in the piezoelectric ceramic plate 21. The friction member 25 has been adapted to elliptical motion by the resultant force of these vibrations.

Then, for example, PID calculation processing is performed by the drive control unit 18 in accordance with the deviation between the position information from the position detection means 17 accompanying the movement of the stage 13 and the reference position information based on the preset movement profile of the stage 13. The result is output to the driver 19 as a command signal, and the driver 19 outputs a driving voltage to the ultrasonic motor 20 to perform feedback control for driving the ultrasonic motor 20. It should be noted that the determination of the P term, I term, and D term, which are control parameters for performing the PID calculation, is carried out by experiments so that the position deviation and positioning accuracy during the movement of the stage 13 satisfy the standard before actual driving. It came to be decided by mistake.

  However, in the structure of the ultrasonic motor 20, when the stage is driven by the ultrasonic motor and stopped for positioning, the spring 27 and the friction member 25 installed to hold the vibrating body 24 are driven. Since the vibrating body does not stop immediately due to the influence of the elastic force of the elastic body such as the spring 28 installed for pressing against the force transmission member, it is very difficult to perform highly accurate positioning.

  In order to solve this problem, in an ultrasonic motor in which a piezoelectric element is fixed to a vibrating body, and a moving body is brought into pressure contact with the vibrating body, a first end is fixed to the vibrating body with one end surface as a base. The first and second piezoelectric elements are fixed perpendicularly to the surface on which the first piezoelectric element is fixed to the vibrating body and opposed in a straight line, and one end surface is fixed, and the opposite surfaces are fixed to the base. There has been proposed an ultrasonic motor having a structure as shown in FIG. 7 characterized in that the piezoelectric elements move in opposite directions (see Patent Document 1).

  Also, the first piezoelectric element having one end face as a base and the other end face fixed to a connecting body, and one end face fixed to the opposite surface of the connecting body to which the first piezoelectric element is fixed, and the other end face fixed to the base. The second piezoelectric element, the third piezoelectric element fixed to the coupling body so as to have a right-angle relationship with the first and second piezoelectric elements, and directly on the other end surface of the third piezoelectric element, or There has been proposed an ultrasonic motor including a moving body that is brought into pressure contact with a driving member (see Patent Document 2).

  Further, a first piezoelectric vibrator having one end as a base and the other end fixed to a first connecting body, and an angle forming a right angle with the first piezoelectric vibrator horizontally or vertically to the first connecting body. The second piezoelectric vibrator, the second connecting body fixed to the other end of the second piezoelectric vibrator, and the second connecting body perpendicularly or horizontally to the second piezoelectric vibrator. An ultrasonic motor including a third piezoelectric vibrator fixed at an angle formed, a driving body fixed to the other end of the third piezoelectric vibrator, and a moving body in pressure contact with the driving body has been proposed. (See Patent Document 3).

  A first piezoelectric vibrator having one end fixed to the base; a first connecting body attached to the other end of the first piezoelectric vibrator; and one end fixed to the first connecting body; and A drive unit of a drive unit fixed to the other end of the second piezoelectric vibrator and a second piezoelectric vibrator that vibrates at an angle with the vibration direction of the first piezoelectric vibrator, and the drive unit Has a fixed portion in common with the first piezoelectric vibrator, is disposed symmetrically with respect to the fixed portion, and has one end fixed to the base in a state where the movable body is in pressure contact with the driving body. There has been proposed an ultrasonic motor characterized in that the vibrators are driven by signals having opposite phases and opposite polarities, and the piezoelectric vibrators to which the driving bodies are fixed are driven by signals having the same phase and the same polarity ( (See Patent Document 4).

A first laminated piezoelectric element having one end fixedly supported; a resonator fixed to the other end of the first laminated piezoelectric element; and the resonance in a direction other than a vibration direction of the first laminated piezoelectric element. There has been proposed an ultrasonic motor including a second laminated piezoelectric element having one end fixed to a container and an additional mass attached to the other end of the second laminated piezoelectric element (see Patent Document 5).
Japanese Patent Laid-Open No. 2-60474 Japanese Patent Laid-Open No. 2-87981 Japanese Patent Laid-Open No. 2-143475 JP-A-2-231967 JP-A-6-70565

  In the proposal of the ultrasonic motor using a plurality of piezoelectric elements shown in Patent Documents 1 to 5, since the elastic body like the conventional ultrasonic motor shown in FIG. 4 is not used, the driving of the ultrasonic motor is not performed. When stopping, it was considered that positioning with higher accuracy was possible.

However, in the ultrasonic motor having the structure as described in Patent Documents 1 to 5, when the piezoelectric elements 31 and 33 are displaced as shown in the schematic diagram of FIG. Although it is good if the driving state is always translated, as shown in FIGS. 7B and 7C, the entire displacement amount of the piezoelectric element is not reflected in the movement of the driving body 30. There was a problem. That is, if the movement of the driving body 30 as shown in FIGS. 7B and 7C occurs in one ultrasonic motor, the driving performance of the ultrasonic motor is not stable. Variations in distance occur.
And in a drive device equipped with such an ultrasonic motor, high-accuracy positioning could not be performed.

  Further, FIG. 7 shows the movement of the driving body with respect to the displacement of the piezoelectric elements 31 and 33. However, if the movement of the piezoelectric element 32 displaced in the direction perpendicular to the surface of the movable body interferes with this, FIG. ), The movement of the driving body 30 shown in (c) is not more constant. In that case, in some cases, the movable body 35 could not be moved by the ultrasonic motor.

In view of the above problems, the present invention is a drive device for frictionally driving a movable body, and is arranged along the moving direction of the movable body so as to sandwich the drive body, and each one end thereof There is fixed to the drive member, a first piezoelectric element unit and the second piezoelectric element portion which the other end is fixed to the holding portion is fixed to the friction members hand end abuts against the movable member, the other end Of the third piezoelectric element portion fixed to the drive body and the third piezoelectric element portion in the movement direction of the movable body so that the drive body can move parallel to the movement direction of the movable body. and a guide portion for supporting the該駆body on both sides, said by applying an alternating voltage at a predetermined period to the first to third piezoelectric element portion, said friction member by an ellipse driven, the movable body Is configured to be movable.

Also preferably, said said third side piezoelectric element portion is formed in the drive member on the opposite side, wherein the guide portion is provided.

Further preferably, the guide portion is a parallel hinge spring in which a plurality of hinges having one end fixed and the other end connected to the driving body are arranged in parallel.

Preferably, the guide portion is a linear motion rolling guide.

Further, preferably, before Symbol friction member, characterized by comprising the sintering of a composite material mainly containing alumina and titanium carbide.

Preferably, the titanium carbide content in the composite material is 10 to 50% by mass.

According to the configuration of the present invention, by forming the guide portion that can move the driving body in parallel with the moving direction of the movable body, the displacement of the piezoelectric element of the piezoelectric element portion can be transmitted to the driving body without loss, As a result, the kinetic energy of the driving body can be transmitted to the movable body without loss, so that the driving device can be in a good driving state, and high-precision positioning can be stably performed. It becomes.

  In addition, since the guide portion is formed on the side opposite to the side surface on which the third piezoelectric element portion of the driving body is formed, the vibration of the third piezoelectric element portion is caused by the first and second piezoelectric elements. Since it is not easily affected by the displacement of the element part and the piezoelectric element parts do not interfere with each other, the displacement of the piezoelectric element of the piezoelectric element part can be transmitted to the driving body without loss, and thereby the kinetic energy of the driving body Can be transmitted to the movable body without any loss, so that the drive device can be brought into a better driving state, and more accurate positioning can be stably performed.

  Furthermore, since the guide portion is a parallel hinge spring that joins the drive body and the main body, the drive portion can be further reduced in size compared to the case where other parts such as a cross roller guide are used as a guide member. Can be made compact. Further, since there is no sliding portion, maintenance such as supply of lubricating oil or replacement of parts due to wear of members is unnecessary, and a drive device that does not require maintenance costs can be obtained.

  In addition, since the friction member is made of a sintered body of a composite material mainly containing alumina and titanium carbide, it is possible to reduce wear and degranulation of the friction member due to friction driving, and to stabilize the contact state of the friction member to the movable body. In addition, it is possible to generate titanium oxide having a friction coefficient larger than that of alumina or titanium carbide on the contact surface of the friction member during friction driving, even when the driving device of the present invention is driven at high speed, Sliding between the friction member and the movable body hardly occurs, and the stage can be moved at a high speed.

  Further, by setting the titanium carbide content in the sintered body of the composite material to 10 to 50% by mass, it is possible to greatly improve the wear resistance of the friction member, and the friction between the friction member and the movable body. The wear resistance of the friction member can be maintained even when the drive is performed for a long time.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 shows a schematic diagram of an example of a drive device of the present invention using an ultrasonic motor as a drive source for a movable body.

  A driving device 10 as an example of the present invention shown in the figure includes a pair of guide members 12 such as cross roller guides on a base board 11, and a stage 13 as a movable body can be linearly reciprocated by these guide members 12. To guide you.

  Further, the stage 13 has a driving force transmission member 14 attached to one side of the stage 13 in parallel with the guide member 12, and a linear scale 15 parallel to the driving force transmission member 14 on the other side of the stage 13. The measuring head 16 is provided at a position facing the linear scale 15 to form the position detecting means 17, and the ultrasonic motor 9 is disposed at a position facing the driving force transmitting member 14. The friction member 5 of the ultrasonic motor 9 is brought into contact with the contact surface of the driving force transmission member 14 perpendicularly.

  In the figure, 18 is a control unit for controlling the driving conditions of the stage 13 based on the position information obtained from the position detection means 17, and 19 is the ultrasonic motor 9 based on the signal output from the control unit 18. It is a driver that outputs a driving voltage for driving.

  Next, FIG. 2 shows an example of the ultrasonic motor 9 installed in the driving apparatus of the present invention shown in FIG. 2A is a schematic plan view, and FIG. 2B is a schematic view when (a) is viewed from the A direction.

  As shown in FIG. 2, the ultrasonic motor 9 used in the driving apparatus 10 of the present invention includes a first piezoelectric element portion 3a having one end fixed to the main body 1 via a fixing portion 2, and a second piezoelectric element. A drive body 8 sandwiched between the portions 3b, a third piezoelectric element portion 4 having one end connected to the drive body 8 and the other end having a friction member 5 via a friction auxiliary member 6, and the drive body 8 And the guide part 7 provided between the fixed part 2. As shown in FIG. 2B, the driving body 8 is installed with a gap from the main body 1, and the driving body 8 vibrates by driving the piezoelectric element portion.

  Here, since the friction member 5 needs to have wear resistance against sliding with the driving force transmission member 14 of the stage 13 shown in FIG. 1, alumina, zirconia, or single crystal alumina, alumina and titanium carbide. The composite material is made of Altic or the like.

In particular, the friction member 5 is preferably made of a composite material of alumina and titanium carbide. This composite material is composed of alumina having high hardness and high melting point (Vickers hardness (H _V ): 18 GPa, melting point: 2100 ° C.), and titanium carbide having higher hardness, higher melting point and higher toughness than alumina (Vickers hardness). (H _V ): 28 GPa, melting point: 3200 ° C., fracture toughness value: 6 MPam ^1/2 ), the friction drive with the driving force transmission member 14 of the stage 13 that is the movable body. Since the contact surface of the friction member 5 is not easily worn, and it is difficult for the grains to be shattered or cracked, the wear of the driving force transmission member 14 can be reduced. It can be stabilized.

  Moreover, when the alumina and titanium carbide composite material forming the friction member 5 is slid at a high speed with the driving force transmission member 14, a chemomechanical reaction occurs in which titanium carbide reacts with oxygen in the atmosphere by frictional heat, Since titanium oxide having a friction coefficient larger than that of alumina or titanium carbide can be generated on the contact surface of the friction member 5, even if the ultrasonic motor 9 is driven at high speed, the friction member 5 and the driving force transmission member 14 The stage 13 can be moved at high speed with almost no slippage between the two.

  By the way, the content of titanium carbide in the composite material of alumina and titanium carbide forming the friction member 5 is preferably 10 to 50% by mass. This is because when the content of titanium carbide is less than 10% by mass, the effect of improving the mechanical properties such as hardness, strength and toughness of the alumina sintered body is small, and when the ultrasonic motor 9 is driven at high speed. This is because the effect of preventing slipping is small. Conversely, when the content of titanium carbide exceeds 50% by mass, the content of titanium carbide that tends to decrease the hardness when exposed to high temperatures becomes excessive. This is because, when the friction drive with the driving force transmission member 14 takes a long time, the friction member 5 wears.

  Moreover, in the composite material of alumina and titanium carbide, oxides such as Mg, Zr, Si, and Y are added as auxiliary components such as sintering aids in addition to alumina and titanium carbide. Since Zr, Si, Y, etc. are paramagnetic metals, if the content of this oxide is excessive, the composite material becomes magnetic, and the content of paramagnetic metal oxide is 7% by mass. If it exceeds, the maximum magnetic flux density of the composite material exceeds 0.05 μT, and it cannot be used for an application that dislikes a magnetic material, for example, a driving device such as an electron beam exposure apparatus. Therefore, when the content of the paramagnetic metal oxide to be contained as an auxiliary component is less than 0.1% by mass, it becomes difficult to obtain a sintered body.

  Therefore, the content of the paramagnetic metal oxide contained as an auxiliary component may be 0.1 to 7% by mass, and if contained within this range, the maximum magnetic flux density is 0.05 μT or less and the hardness is increased. be able to.

  The balance is mainly composed of alumina and titanium carbide, but the alumina, titanium carbide, and sintering aid may be mixed in trace amounts as long as they are inevitable impurities such as those contained in paramagnetic metal oxides. .

  The maximum particle diameters of the alumina crystal and the titanium carbide crystal in the sintered body of the composite material are preferably 4 μm or less, and the maximum pore diameter of the sintered body of the composite material is preferably 2 μm or less.

  Here, the maximum particle diameter of each of the alumina crystal and the titanium carbide crystal is set to 4 μm or less. If the maximum particle diameter of each crystal particle exceeds 4 μm, the contact of the friction member 5 occurs when degranulation or cracking occurs. This is because a large concave portion is formed on the surface, the driving force transmission member 14 is easily damaged, and the friction member 5 is abraded, and the maximum pore size of the composite material sintered body is set to 2 μm. This is because if the maximum pore diameter exceeds 2 μm, degranulation and cracking are likely to occur.

  In addition, if the surface roughness of the contact surface of the friction member 5 with the driving force transmission member 14 is rough, the driving force transmission member 14 that is the mating member may be scratched in the initial familiarization process, and the wear may be abrupt. As a result, the contact surface of the friction member 5 will be severely worn. For this reason, it is preferable that the contact surface of the friction member 5 be 0.2 μm or less in terms of arithmetic average roughness (Ra).

  By the way, in order to obtain a sintered body of a composite material mainly containing alumina and titanium carbide as described above, 32 to 91% by mass of alumina powder having a particle size of 0.3 to 1.5 μm and a particle size of 0.3 9 to 68% by mass of titanium carbide powder having a thickness of 1.5 μm and 0.1 to 7% by mass in total of oxides made of paramagnetic metals such as Mg, Zr, Si and Y as sintering aids After preparing a slurry of the mixed powder added in step 1 and forming it into a predetermined shape by a known ceramic forming method such as a uniaxial pressure forming method, an isostatic forming method, an injection forming method, etc., a temperature of 1600 to 1750 ° C. in a vacuum atmosphere It can obtain by baking with. Moreover, by pressurizing at a pressure of about 20 to 40 MPa during firing, the maximum particle diameter of the alumina crystal and the titanium carbide crystal can be 4 μm or less, and the maximum pore diameter of the composite sintered body can be 2 μm or less.

  If the sintered body of the composite material mainly containing alumina and titanium carbide obtained under such conditions is used as the friction member 5 of the ultrasonic motor 9 of the present invention, the drive force transmission member 14 of the stage 13 In the friction drive, not only the wear of the friction member is small, but also the wear of the driving force transmission member 14 which is the counterpart member can be suppressed and the occurrence of scratches can be reduced, so that the drive device can be driven for a long period of time. At the same time, since it is possible to reduce the presence of the pulverized powder between the friction member 5 and the driving force transmission member 14, the contact state between the friction member 5 and the driving force transmission member 14 can be stabilized.

  The first and second piezoelectric element portions 3a and 3b are composed of piezoelectric elements having one end symmetrically connected to the left and right of the drive body 8 and the other end connected to the fixed portion 2, and vibrate to the drive body 8. Can be added. In this case, it is installed so that the expansion and contraction are reversed when a voltage is applied to the two piezoelectric element portions. By doing so, the driving body 8 can be vibrated.

The piezoelectric element can have a structure as shown in FIG. 3, for example. FIG. 3A shows the structure of the piezoelectric element, and FIG. 3B shows the structure for attaching the piezoelectric element 40 to the ultrasonic motor 9. As shown in FIG. 3A, the piezoelectric element 40 has a donut shape, and an electrode film 42 is formed on the surface of a piezoelectric ceramic body 41 having a thickness of about 0.5 to 3 mm and polarized in the thickness direction. Yes. Then, as shown in FIG. 3B, a plurality of piezoelectric elements are attached by a fixing screw 44 via a metal spacer 43 between the fixing portion 2 and the driving body 8, thereby the first, A second piezoelectric element portion is formed.

  The third piezoelectric element portion 4 is composed of a piezoelectric element similar to the first and second piezoelectric element portions 3, and a friction member 5 is attached to one end via a friction auxiliary member 6. The end is fixed to the driving body 8. As a method of fixing the friction member 5, there is a method of bonding using an adhesive.

  Then, the driving body 8 is vibrated by the first, second and third piezoelectric element portions 3 a, 3 b, 4, and the kinetic energy of the driving body 8 is installed on the stage 13 which is a movable body through the friction member 5. The stage 13 is driven by transmitting it to the driving force transmitting member 14 in the form of elliptical motion. At this time, the driving body 8 has already been moved against the displacement of the piezoelectric elements of the first, second and third piezoelectric element portions. As described in the problem of the prior art, the drive shown in FIG.

  Therefore, in the present invention, the displacement of the first, second, and third piezoelectric element portions whose one end is connected to the driving body 8 and the other end is connected to the fixed portion 2 is suppressed in directions other than the vibration direction. The guide portion 7 that can perform the above-mentioned is installed in a form that does not hinder the displacement of each piezoelectric element portion in the vibration direction. FIG. 2A shows a structure in which a parallel hinge is attached as the guide portion 7 as an example. By providing this parallel hinge on the side opposite to the side surface on which the third piezoelectric element portion of the driving body 8 is formed, as shown by an arrow in FIG. The drive body 8 can be vibrated satisfactorily according to the vibration direction of the element portion, and the drive body 8 can be prevented from vibrating in directions other than the vibration direction of the piezoelectric element portion. Therefore, it is possible to stably transmit the vibrations of the piezoelectric element portions through the friction member 5 to the driving force transmission member 14 of the stage 13 which is a movable body in the form of elliptical driving.

  Here, it is shown as an example that a parallel hinge is installed as the guide portion 7, but linear motion rolling guides such as a cross roller guide and an LM guide (known as a trademark of THK Co., Ltd.) are also guided. Applicable as part 7. However, linear motion rolling guides such as cross roller guides and LM guides have sliding parts unlike parallel hinges, and maintenance such as periodic replacement of guide parts is required due to deterioration of members due to wear. In view of cost, it is preferable to use a parallel hinge.

  The amplitude angle due to the vibration of the parallel hinge shown in FIG. 2 (c) is actually very small. When the length of the parallel hinge is 5 to 10 mm and the amplitude is around 10 μm, the amplitude angle is 0. It is about 005 deg.

  The third piezoelectric element portion 4 has one end surface fixed at the maximum displacement position of the first and second piezoelectric element portions 3a and 3b, and the other end surface connected and held to the driving body 8 more. Otherwise, the drive body 8 cannot be vibrated by making the most of the amount of displacement of both piezoelectric element portions. Therefore, the kinetic energy produced by the vibration is small, and driving as an ultrasonic motor is possible. Characteristics are degraded.

  Furthermore, it can be said that the first and second piezoelectric element portions 3a and 3b vibrate in the same direction with respect to the vibration direction. For this reason, it is not always necessary to have two piezoelectric elements as described above. For example, a structure as shown in FIGS. 4A and 4B may be used.

That is, as shown in FIG. 4, a predetermined vibration trajectory is obtained by synthesizing vibration parts 3 and 4 that generate vibrations in two directions mainly different from the movable body and vibrations in two directions different from each other in the main body 1. And a driving body 8 having a friction member 5 that is in sliding contact with the movable body, and the movable body is driven by the driving body 8, and at least one of the vibrating portions has a vibration direction thereof. And a guide portion 7 that suppresses displacement in a different direction. If there is such vibration in two directions, a vibration trajectory such as an ellipse can be drawn on the friction member 5 by synthesizing the vibrations, and the movable body that is in sliding contact with the friction member 5 can be driven. is there. Furthermore, by installing a guide portion to suppress the displacement that tries to vibrate in directions other than the two directions, the vibrations in the two directions can be synthesized without loss, and a stable vibration trajectory can be generated. In the driving device equipped with the ultrasonic motor 9 having the structure, higher positioning accuracy can be obtained.

  FIG. 4A shows a first vibrating part 3 which is composed of one piezoelectric element, one end connected to the driving body 8 and the other end fixed to the fixing part 2 fixed to the main body 1, and the vibration direction of the first vibrating part 3. A second vibrating part 4 installed at a right angle to the driving body 8 and the fixed part 2 at both ends, and an LM guide disposed between the driving body 8 and the fixing part 2 in parallel with the second vibrating part 4 Or it is comprised by the guide part 7 which consists of linear motion rolling guides, such as a cross roller guide. One movable part of the linear motion rolling guide such as the LM guide or the cross roller guide is fixed to the main body 1, and the other movable part is connected to the fixed part 2 and the driving body 8, thereby the vibration direction of the vibration part. It is possible to suppress displacement to other than the above, and to stably support and fix the driving body 8 at a predetermined position.

  Here, the first vibrating part 3 and the second vibrating part 4 have one end connected to the main body and the other end connected to the driving body 8, and each vibrating part is polarized in the thickness direction of the donut shape already described above. The piezoelectric element thus formed is screwed to the fixing portion 2 via a metal spacer.

  The vibrating parts 3 and 4 have a structure in which one of the vibrating parts is fixed at least at one end with respect to the main body 1 and the other vibrating part is fixed at one end at the maximum displacement position of the vibrating part. It is preferable that With such a structure, it is possible to make maximum use of the displacement of the vibration part, and it is possible to apply a greater vibration to the driving body 8 to which one end of the vibration part is connected.

  In FIG. 4B, the first and second vibrating portions 3 and 4 are arranged, and a guide portion 7 composed of a linear motion rolling guide such as a cross roller guide or an LM guide is provided at a position parallel to each vibrating portion. It has a provided structure. As can be seen from this example, the vibration part does not necessarily need to be installed in a direction parallel to or perpendicular to the moving direction of the stage 13, and transmits vibration to the driving body 8 as shown in FIG. As long as a predetermined vibration trajectory can be drawn on the member 5, any installation direction may be used.

In the present invention, the movable body, two vibration portions that mainly generate vibrations in two different directions, and a predetermined vibration locus are generated by combining the vibration portions in two different directions, and the movable body A driving body having a friction member that is in sliding contact with the driving body, and driving the movable body by the driving body, wherein at least one of the vibrating portions includes a guide portion that suppresses displacement in a direction different from the vibration direction. By having the structure, it is possible to synthesize vibrations in two different directions of the vibration part with less loss and transmit them to the drive body and the friction member of the drive body, and also stable vibration by the friction member It is possible to draw a trajectory, and it is possible to perform positioning with higher accuracy in the driving device of the present invention.

  In addition, since one end of each vibration part is fixed to the main body and the other end is fixed to the drive body, vibration of the vibration part can be transmitted to the drive body with little loss. In addition, the driving body can be supported only by the vibrating portion and securely fixed.

  Further, of the two vibrating parts, one vibrating part is constituted by a first vibrating part fixed at least one end to the main body, and the other vibrating part is the maximum of the first vibrating part. Displacement position
The first and second vibrating parts do not interfere with each other, and the vibrations of the vibrating parts are synthesized with less loss. It becomes possible.

  In addition, since the parallel hinge spring is fixed to the same member as each vibration part, the vibration direction of the vibration part can be the same direction as the contraction direction of the spring of the parallel hinge spring. The deviation can be reduced, and the vibration of the vibration part can be transmitted to the drive body with even less loss.

  Furthermore, even in the structure shown in FIG. 2 described above, it is possible to cause the friction member 5 to draw a predetermined vibration locus if the structure has either one of the piezoelectric element portions 1 or 2. At this time, it is necessary to consider whether one end of the piezoelectric element portion 1 or 2 and the piezoelectric element portion 3 is fixed at one of the maximum displacement positions.

  In any case, the structure of the ultrasonic motor used in the drive device of the present invention is not limited to the structure shown in FIGS. 2 and 4, and is limited by the number of piezoelectric elements installed in the piezoelectric element section. As long as it has a structure having the guide portion 7 similar to these, any structure can be used as the ultrasonic motor used in the driving device.

  Next, the driving state of the driving device of the present invention will be described with reference to FIG.

  First, when a command signal is output from the driver 19 and the friction member 5 of the ultrasonic motor 9 is elliptically moved, the stage 13 can be moved along the guide member 12 by friction drive with the driving force transmission member 14. The controller 18 performs, for example, a PID calculation process based on a parameter that changes in accordance with the deviation between the position information from the position detection means 17 accompanying the movement of the stage 13 and the preset reference position information of the stage 13. Thus, the stage 13 is moved under a predetermined condition by performing feedback control for outputting a command signal to the ultrasonic motor 9 to the driver 19.

  At this time, according to the drive device of the present invention, unlike the conventional ultrasonic motor, since the structure using the elastic body is not used, when the stage 13 is stopped for positioning, it is caused by the reaction caused by the elastic force. Since there is no inconvenience that the positioning cannot be performed with high accuracy, and the movement of the driving body that transmits the kinetic energy in the ultrasonic motor to the driving force transmission member 14 of the stage 13 is stable, and there is no loss. Even when high accuracy is required such that the accuracy during movement is 1 μm or less and the positioning accuracy is 0.1 μm or less, it is possible to provide a drive device that can move and position more stably and with high accuracy.

  The driving device of the present invention as described above can maintain high-precision driving for a long period of time when introduced into a manufacturing process for a semiconductor or liquid crystal manufacturing apparatus. It can be said that it is optimal as a driving device for the apparatus.

  Needless to say, the present invention can be applied to various improvements and modifications as long as they do not depart from the gist of the present invention.

  Examples of the present invention will be described below.

  A drive device equipped with the ultrasonic motor shown in FIG. 2 of the present invention, a drive device equipped with a conventional ultrasonic motor using an elastic body, and a drive device equipped with an ultrasonic motor having the structure shown in FIG. 7 are prepared. Then, a test for comparing the positioning accuracy during the driving was performed.

  As for the driving device used in the test, a cross roller guide having a stroke of 100 mm was used for the guide member 12 constituting the driving device, and the stage 2 having a weight of 5 kg was moved by the guide member 12. . A driving force transmission member made of alumina ceramic was disposed on one side surface of the stage 2, and the surface roughness of the contact surface with the ultrasonic motor 40 was set to 0.05 μm in arithmetic mean roughness (Ra).

  On the other hand, for the ultrasonic motor that is the drive source of the stage 2, the piezoelectric element used is a lead zirconate titanate-based piezoelectric ceramic body, and the friction member is a 4.2 mm long and 3 mm diameter alumina ceramic ceramic. The product made in common was used for the ultrasonic motor of each drive device. The contact surface of the friction member with the driving force transmission member was a spherical surface with a radius of curvature of 7 mm.

  In the experiment, as the movement profile of the stage 2 set in advance in the control unit 9, the trapezoidal control is set such that the movement distance is 100 mm, the acceleration / deceleration is 0.03 G, and the maximum speed is 100 mm / sec, and the ultrasonic motor is driven at a driving frequency of 40 kHz. It was made to drive for 30 hours.

  As a result of the test, the positioning accuracy at the time of driving was 0.1 μm for the driving device equipped with the conventional ultrasonic motor using the elastic body.

  Further, in the driving apparatus equipped with the ultrasonic motor having the conventional structure shown in FIG. 6, the positioning accuracy is also 0.1 μm, but there are many variations in accuracy and the driving state of the ultrasonic motor is poor. , Stopped after 20 hours.

  Compared with this, the drive device of the present invention can perform positioning with an extremely high accuracy of 0.05 μm, and further, there is little variation, and an extremely good drive is performed compared to other devices. I was able to.

  Next, in the driving apparatus 10 shown in FIG. 2 of the present invention used in Example 1, the friction member 5 of the ultrasonic motor 20 is made of alumina and made of a composite material mainly containing alumina and titanium carbide. Then, an experiment was conducted to compare the driving states.

  The configuration of each part of the drive device is the same as that of the first embodiment.

  As for the operating conditions of the driving device, as the movement profile of the stage 13 set in advance in the control unit 18, the trapezoidal control is set such that the movement distance is 100 mm, the acceleration / deceleration speed is 0.03 G, and the maximum speed is 100 mm / sec. The motor 20 was driven at a driving frequency of 40 kHz.

  Under these conditions, the wear amount of the friction member 5 and the wear amount of the driving force transmission member 14 after the stage 13 was driven by a distance of 500 km were measured.

  Further, before starting the experiment, the contact surface of the friction member 5 with the driving force transmission member 14 is observed with a scanning electron microscope at a magnification of 2000 times, and the crystal particles and the maximum pore diameter on the contact surface are measured. In addition, a rectangular parallelepiped having a length of 3 mm, a width of 3 mm, and a thickness of 1.2 mm is manufactured from the same material as that for forming the friction member 5, and a maximum magnetic flux density is obtained using a magnetometer (Tokyo Instruments 2900-04C type). Was measured.

  The results are shown in Table 1.

  As is apparent from Table 1, the friction member 5 of the ultrasonic motor 20 is formed of a composite material sintered body mainly containing alumina and titanium carbide, and the sample No. Sample Nos. 2 to 29 are samples Nos. 2 to 29 in which the friction member of the ultrasonic motor 20 is formed of alumina. It can be seen that the wear of the friction member 5 and the driving force transmission member 14 can be suppressed compared to 1.

As a result, in order to increase the life of the ultrasonic motor 20 and suppress wear of the counterpart member, the friction member 5 of the ultrasonic motor 20 is formed of a composite material sintered body mainly containing alumina and titanium carbide. It can be seen that it should be used. Sample No. It was also confirmed that a titanium oxide film was formed on the contact surfaces of the friction members 5 of 2 to 29, and the frictional force was increased by the titanium oxide film.

  Further, when attention is paid to the friction member 5 of the ultrasonic motor 20 formed by a composite material sintered body mainly containing alumina and titanium carbide, the titanium carbide content in the composite material sintered body is determined as follows. Sample No. 10 to 50 mass%. 5-7 and sample no. Nos. 21 to 23 are sample Nos. With titanium carbide content exceeding the above range. 2-4 and Sample No. It can be seen that the wear amount of the friction member 5 and the driving force transmission member 14 can be suppressed as compared with 18-20.

  Sample Nos. 1 and 2 in which the maximum particle size of the alumina crystal and the titanium carbide crystal in the composite material sintered body is 4 μm or more and the maximum pore diameter of the composite material sintered body is 2 μm or less. 8-10 and Sample No. 24-26 are sample Nos. Having other ranges. 5-7 and sample no. It can be seen that the wear amount of the friction member 5 and the driving force transmission member 14 can be reduced as compared with 21 to 23.

  As a result, in order to further suppress the wear amount of the friction member 5 and the drive amount transmission member 14, the titanium carbide content in the sintered body of the composite material is set to 10 to 50% by mass, and the composite material is sintered. It can be seen that the maximum particle size of the alumina crystal and titanium carbide crystal in the body may be 4 μm or less and the maximum pore size is 2 μm or less.

  Furthermore, the sample No. 2 in which the content of the auxiliary component composed of a paramagnetic metal oxide is 7% by mass or more. In 3 to 10, 15, 17, and 19 to 26, the maximum magnetic flux density of the friction member 5 exceeded 0.05 μT.

  As a result, it is understood that the content of the auxiliary component composed of paramagnetic metal oxide is preferably 7% by mass or less.

It is a schematic diagram which shows an example of the drive device of this invention. It is an example of the structure of the ultrasonic motor used for the drive device of this invention, (a) is a plane schematic diagram, (b) is the schematic diagram seen from A direction of (a), (c) is the super structure of this invention. The plane schematic diagram which shows the drive state of a sonic motor, mainly a motion of a guide part is shown. It is a schematic diagram which shows an example of the piezoelectric element used for the drive device of this invention, (a) is a piezoelectric element, (b) is a schematic diagram which shows the attachment structure. It is an example of the ultrasonic motor used for the drive device of this invention, (a), (b) is a plane schematic diagram which shows the other structural example. It is a schematic diagram which shows an example of the conventional drive device. The structure of the ultrasonic motor used for the conventional drive device is shown, (a) is a plane schematic diagram, (b) is the plane schematic diagram which looked at (a) from the back side. The driving state of the ultrasonic motor used for the conventional drive device is shown, (a) is a good driving state, (b), (c) is a schematic plan view showing the driving state that causes a problem.

1: Body 2: Fixed portion 3a: First piezoelectric element portion 3b: Second piezoelectric element portion 4: Third piezoelectric element portions 5, 25, 34: Friction member 6: Friction assisting member 7: Guide portion 8, 24, 30: driving body 9, 20: ultrasonic motor 10: driving device 11: base board 12: guide member 13: stage 14: driving force transmitting member 15: linear scale 16: measuring head 17: position detecting means 18: control Unit 19: driver 21: piezoelectric ceramic plate 22: electrode film 23: electrode 26: case 27, 28: spring 31, 32, 33: piezoelectric element 35: movable body 40: piezoelectric element 41: piezoelectric ceramic 42: electrode film 43: Spacer 44: Fixing screw

Claims (6)

A driving device for frictionally driving a movable body,
A first piezoelectric element that is arranged along the moving direction of the movable body so as to sandwich the driving body, and has one end fixed to the driving body and the other end fixed to the holding portion. And a second piezoelectric element portion, a third piezoelectric element portion having one end fixed to a friction member abutting on the movable body and the other end fixed to the drive body, and the drive body being the movable body A guide portion that supports the driving body on both sides of the third piezoelectric element portion in the moving direction of the movable body so as to be movable in parallel with the moving direction of
A driving apparatus configured to move the movable body by elliptically driving the friction member by applying an alternating voltage to the first to third piezoelectric element portions at a predetermined cycle. The drive device according to claim 1, wherein the guide portion is provided on a side opposite to a side surface on which the third piezoelectric element portion of the drive body is formed. 3. The drive device according to claim 1, wherein the guide portion is a parallel hinge spring in which a plurality of hinges having one end fixed and the other end connected to the drive body are arranged in parallel. The drive device according to claim 1, wherein the guide portion is a linear motion rolling guide. It said friction member is alumina and the driving device according to any one of claims 1 to 4, characterized in that the sintering of a composite material containing mainly titanium carbide. The drive device according to claim 5 , wherein a content of titanium carbide in the composite material is 10 to 50 mass%.