JP2005261025A - Ultrasonic motor, moving device and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor in which generation of strange sound is suppressed at the time of driving and moving efficiency of a driven body is enhanced. <P>SOLUTION: The ultrasonic motor 10 for friction driving a driven body 40 comprises two ultrasonic vibrators 11a and 11b, a friction sliding part head 13 displacing by butting against the driven body 40 and driving the ultrasonic vibrators 11a and 11b, and a telescopic piezoelectric actuator 15 for controlling the position of the head 13 in the direction being pressed by the driven body 40 at the time of nonresonant driving of the ultrasonic vibrators 11a and 11b. When the head 13 is pulled back reversely to the moving direction of the driven body 40, the head 13 is separated from the driven body 40 by contracting the piezoelectric actuator 15 thus suppressing generation of strange sound and reversion of the driven body 40. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic motor that moves a driven body by friction driving, a moving device including the ultrasonic motor, and a driving method of the moving device.

  As shown in FIG. 9, two ultrasonic transducers 111a and 111b, a holding member 112 that holds the ultrasonic transducers 111a and 111b at a predetermined angle (for example, 90 degrees), and a substantially V-shaped shape. And a head 113 that is in contact with the driven body 101 at the apex portion and connected to the ultrasonic transducers 111a and 111b at the end portion (the V-shaped open side). An ultrasonic motor 100 is known (see, for example, Patent Document 1). The moving device is configured by pressing the head 113 against the driven body 101 by a preload mechanism 114 such as a spring.

  The ultrasonic vibrators 111a and 111b are respectively provided with piezoelectric elements 115a and 115b. For example, when the ultrasonic vibrators 111a and 111b are driven at a resonance frequency voltage whose phase is shifted by 90 degrees (that is, the piezoelectric elements 115a and 115b are phase-shifted). Is applied 90 degrees), the head 113 moves elliptically.

  When the head 113 passes the upper side of the elliptical orbit (the driven body 101 side), the driven body 101 moves due to the frictional force between the head 113 and the driven body 101. On the other hand, when the head 113 passes below the elliptical orbit, the movement of the preload mechanism 114 cannot follow the movement of the head 113, so that the head 113 moves away from the driven body 101 and is substantially free of friction. The driver 101 does not affect the movement of the head 113. Thereby, the driven body 101 can be moved in the direction in which the head 113 moves on the upper side of the elliptical orbit.

The moving speed of the driven body 101 can be adjusted by changing the vibration amplitude of the driving frequency of the ultrasonic motor 100 (that is, changing the driving voltage value). However, in the resonance driving, the moving speed is driven by the inertia of the head 113. Positioning with high accuracy (for example, several tens of nm) is difficult because the head 113 slightly moves even after the voltage is turned off.
JP 2000-152671 A (FIG. 1)

  In order to solve such an inconvenience, the inventors examined non-resonant driving in which the ultrasonic motor 100 is driven at a frequency lower than the resonant frequency as a method of reducing the inertia of the head 113. However, in general, in such non-resonant driving, a change in the force with which the preload mechanism 114 presses the head 113 follows the movement of the head 113, so the head 113 and the driven body 101 Remains in contact with each other due to friction, and the driven body 101 cannot be moved only by moving within a minute range.

  Therefore, the inventors of the present invention previously non-resonantly driven the ultrasonic motor 100 at a frequency lower than the resonance frequency in Japanese Patent Application No. 2003-144803, and at that time, the drive voltage of the ultrasonic motor 100 was rapidly reduced. Thus, a method of moving the driven body 101 by sliding the head 113 from the driven body 101 and repeating it was proposed. According to such a driving method, the driven body 101 can be moved by several tens of nm to several hundreds of nm per one time (one waveform). In addition, positioning accuracy can be improved.

  However, the driving method disclosed in Japanese Patent Application No. 2003-144803 has a new problem that sound is generated when the head 113 is slid. Such abnormal noise is not preferable, for example, as a work environment where the apparatus is installed. Further, since the driven body 101 returns somewhat without the head 113 completely slipping, that is, the movement efficiency is lowered, it is desired to increase the movement efficiency.

  The present invention has been made to solve such a new problem, and provides a moving device that suppresses the generation of abnormal noise and increases the moving efficiency of a driven body, and a driving method thereof. Objective. Moreover, an object of this invention is to provide the actuator used suitably for this moving apparatus.

As a first invention, the present invention is an ultrasonic motor that frictionally drives a driven body,
An ultrasonic transducer,
A friction sliding portion that contacts the driven body and is displaced by driving the ultrasonic vibrator;
A retractable actuator that controls the position of the friction sliding portion in a direction in which the friction sliding portion is pressed against the driven body when the ultrasonic vibrator is driven in a non-resonant manner;
An ultrasonic motor is provided.

  As a preferable form of such an ultrasonic motor, two holding members having a Langevin type structure including a piezoelectric element as an ultrasonic vibrator are provided, and a holding member that holds these two ultrasonic vibrators at a predetermined angle. And having a substantially V-shaped shape as a frictional sliding portion so as to be in contact with the driven body at the apex portion thereof and to be connected to the two ultrasonic transducers at the end portions thereof, respectively. In this case, the actuator is attached to the holding member.

As a second invention, the present invention provides a moving apparatus provided with such an ultrasonic motor. That is, a moving device that moves the driven body by friction driving the driven body with an ultrasonic motor,
The ultrasonic motor includes an ultrasonic vibrator, a friction sliding portion that is in contact with the driven body and is displaced by driving the ultrasonic vibrator, and the friction sliding portion is moved with a constant force. A preload mechanism that presses against the drive body, and an actuator that is displaceable in a direction in which the preload mechanism presses the friction sliding portion,
Provided is a moving device comprising an actuator control device for driving the actuator to control the position of the frictional sliding portion when the ultrasonic motor is driven non-resonantly.

  The preferred form of the ultrasonic motor used in such a moving apparatus is the same as that of the first invention. That is, as an ultrasonic motor, two Langevin type ultrasonic transducers provided with a piezoelectric element, a holding member for holding these two ultrasonic transducers at a predetermined angle, and a substantially V-shaped shape. And a frictional sliding portion that is in contact with the driven body at the apex portion and is connected to the two ultrasonic vibrators at the end portion.

The present invention provides, as a third invention, a driving method for a moving device according to the second invention,
When the friction sliding portion is moved in the opposite direction with respect to the direction in which the driven body is frictionally moved to pull back the friction sliding portion, the friction sliding portion and the driven body are substantially separated from each other. Thus, there is provided a driving method of a moving device, characterized in that the actuator is displaced.

  In such a driving method of the moving device, the friction applied to the driven body from the friction sliding portion when the moving direction of the friction sliding portion is the same as the moving direction of the driven body. The actuator is extended so that the force is increased, while the direction in which the friction sliding portion moves is opposite to the direction in which the driven body is moved to pull back the friction sliding portion. It is preferable to reduce the actuator so that the driving body and the friction sliding portion are separated from each other.

  According to such a moving device and its driving method, when the ultrasonic motor is driven non-resonant or DC, the frictional sliding surface of the ultrasonic motor is not slid in a state where it is in contact with the driven body. Generation of sound can be prevented, and return of the driven body can also be prevented. As a result, the driven body can be moved silently at high speed. In addition, highly accurate positioning is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic structure of the ultrasonic motor 10. The ultrasonic motor 10 is different from the ultrasonic motor 100 previously shown in FIG. 9 only in that the ultrasonic motor 10 includes a piezoelectric actuator 15. Here, the structure of the ultrasonic motor 10 is described in detail. It will be explained in the following.

  The ultrasonic motor 10 is in contact with two driven vibrators 40, two ultrasonic vibrators 11 a and 11 b having a Langevin type structure, a holding member 12 that holds the ultrasonic vibrators 11 a and 11 b at an angle of 90 degrees. The head 13 has a substantially V-shape and the piezoelectric actuator 15 attached to the holding member 12. A preload mechanism 14 is attached to the piezoelectric actuator 15 to press the head 13 against the driven body 40 with a predetermined force via the piezoelectric actuator 15 and the holding member 12. The driven body 40 is attached to a guide (not shown) extending in the X direction and is movable in the X direction.

  The ultrasonic transducer 11a includes a bolt 21 having both ends threaded, a cap nut 22 having a screw hole that fits into a screw groove of the bolt 21, and two ring-shaped piezoelectric plates through which the bolt 21 can pass. 23a and 23b, and ring-shaped electrode plates 24a to 24c through which the bolts 21 can pass. Similar to the ultrasonic transducer 11a, the ultrasonic transducer 11b includes a bolt 21 ', a cap nut 22', two ring-shaped piezoelectric plates 23a 'and 23b', and ring-shaped electrode plates 24a 'to 24a'. 24c '. The holding member 12 is provided with holes for allowing the bolts 21 and 21 'to pass therethrough. The number of piezoelectric plates provided in one ultrasonic transducer is arbitrary and is not limited to two.

  The head 13 connects the contact portion 13a in contact with the driven body 40, the connection portions 13b and 13b 'connected to the ultrasonic transducers 11a and 11b, and the contact portion 13a and the connection portions 13b and 13b'. Neck portions 13c and 13c 'are formed, and screw holes for fitting into the screw grooves of the bolts 21 and 21' are formed in the connecting portions 13b and 13b ', respectively.

  The piezoelectric plates 23a and 23b are fastened with a predetermined force by the connecting portion 13b of the cap nut 22 and the head 13, thereby obtaining the Langevin type ultrasonic transducer 11a. It is also a component of the acoustic wave oscillator 11a. Similarly, the connecting portion 13b ′ is also a constituent element of the ultrasonic transducer 11b.

  As shown in FIG. 1, the piezoelectric plates 23 a and 23 b are arranged so as to be sandwiched between the electrode plates 24 a to 24 c, and bolts 21 are inserted into the holes of the piezoelectric plates 23 a and 23 b, the electrode plates 24 a to 24 c and the holding member 12. The head 13 and the cap nut 22 are attached to the end portions of the bolts 21, respectively. Accordingly, the piezoelectric plates 23a and 23b are fastened with a predetermined force. Thus, in the ultrasonic motor 10, the head 13 is not only a sliding portion that frictionally drives the driven body 40, but also serves as a member that constitutes a Langevin type vibrator by tightening the piezoelectric plates 23a and 23b. Is responsible. Of course, a Langevin type vibrator constituted by fastening the piezoelectric bodies 23a and 23b with two nuts is prepared, and one nut is attached to the connecting portion 13b of the head 13 by screwing, bonding with an adhesive, welding or the like. Thus, an ultrasonic motor equivalent to the ultrasonic motor 10 may be configured.

  Electrodes (not shown) are formed on the front and back surfaces of the piezoelectric plates 23a, 23b, 23a ', and 23b'. For the piezoelectric plates 23a and 23b, piezoelectric ceramics such as PZT are preferably used. The directions of polarization of the piezoelectric plates 23a and 23b are symmetric with respect to the electrode plate 24b sandwiched between the piezoelectric plates 23a and 23b. The electrode plates 24a and 24c are electrically connected to each other. Therefore, when a voltage is applied between the electrode plate 24b and the electrode plate 24c, the piezoelectric plates 23a and 23b are displaced (vibrated) in the same phase. That is, the piezoelectric plates 23a and 23b extend in the thickness direction or contract together.

  Normally, a metal material is used for the bolt 21, the cap nut 22, and the holding member 12. In this case, the electrode plates 24 a and 24 c are electrically connected to the cap nut 22 through the holding member 12. Therefore, the holding member 12 or the cap nut 22 of the ultrasonic transducer 11a can be used as a ground electrode for driving the piezoelectric bodies 23a and 23b. At this time, the piezoelectric plate 23a ′ included in the ultrasonic transducer 11b. -The ground for driving 23b 'can be taken simultaneously.

  When the piezoelectric plates 23a and 23b of the ultrasonic transducer 11a are expanded and contracted, and at the same time, the piezoelectric plates 23a 'and 23b' of the ultrasonic transducer 11b are expanded and contracted, the neck portions 13c and 13c 'of the head 13 are moved. As a result, the displacements of the ultrasonic transducers 11a and 11b are synthesized at the contact portion 13a, and thereby the contact portion 13a is displaced.

  For the head 13, a material having excellent wear resistance, for example, a metal material such as stainless steel or cemented carbide, or a ceramic such as alumina, silicon nitride, or silicon carbide is used. If the head 13 is made of metal, it is easy to form a screw groove for connecting the bolt 13 to the head 13. Even if the head 13 is made of metal, since the head 13 is electrically connected to the electrode plate 24a, if either the holding member 12 or the cap nuts 22 and 22 'of the ultrasonic transducers 11a and 11b is grounded, the head 13 Are also grounded. It is also preferable that the head 13 is made of a metal material, and the surface of the contact portion 13a is coated with silicon nitride or the like. Alternatively, the head 13 may be made of a metal material, and a ceramic member may be disposed on the contact portion 13 a so that the ceramic member substantially contacts the driven body 40.

  As the piezoelectric actuator 15, an integrally fired piezoelectric actuator is preferably used. Such a piezoelectric actuator 15 can be attached to the holding member 12 using a resin adhesive such as an epoxy resin, for example. When a cylindrical laminated piezoelectric actuator is used, it can be fixed to the holding member 12 by bolting, similarly to the piezoelectric plate 23a and the like.

  For example, an air cylinder, a hydraulic cylinder, a spring, or the like is used as the preload mechanism 14. In FIG. 1, the preload mechanism 14 including a spring (spring coil) 14a is shown. In this case, as shown in FIG. 1, a metal rod 14b shorter than the entire length of the spring 14a is attached to the piezoelectric actuator 15, the spring 14a is arranged so that the metal rod 14b passes through the spring 14a, and the spring 14a is contracted. The other end of the metal rod 14b is fixed to a frame 14c or the like for arranging the ultrasonic motor 10. Accordingly, the head 13 can be pressed against the driven body 40 with a preload corresponding to the amount of contraction of the spring 14a.

  Next, a configuration of a moving device including the ultrasonic motor 10 and a driving method thereof will be described. FIG. 2 is an explanatory diagram showing the configuration of the moving device 50 including the ultrasonic motor 10. The moving device 50 includes a driven body 40, an ultrasonic motor 10 that frictionally drives the driven body 40 and moves the driven body 40 to a predetermined position, a position sensor 45 that detects the position of the driven body 40, and the driven body 40. And a motor drive control device 55 that controls the drive of the ultrasonic motor 10 for movement control and position control.

  The motor drive control device 55 includes a vibrator control means 51 for sending a signal for controlling the drive of the ultrasonic vibrators 11 a and 11 b included in the ultrasonic motor 10, and a control signal sent from the vibrator control means 51. Is provided with a signal adjusting means 52 for converting the drive signal into a drive signal for the ultrasonic vibrators 11a and 11b, and an actuator control means 53 for controlling the drive of the piezoelectric actuator 15 based on a control signal transmitted from the vibrator control means 51. ing.

  In the vibrator control means 51, an instruction value generating unit 51a generates an instruction value for instructing to move the driven body 40 to a predetermined position. On the other hand, the position of the driven body 40 is detected by a position sensor 45 such as a linear gauge, and the data is sent to the vibrator drive controller 51 b of the vibrator controller 51. The transducer drive control unit 51b calculates a deviation between the instruction value sent from the instruction value generation unit 51a and the position data sent from the position sensor 45, and performs, for example, PID calculation processing based on the result, and the head 13 Control signals for driving the ultrasonic transducers 11a and 11b are generated and output.

  Examples of the control signal include a sin wave, a cosine wave, a rectangular wave, a triangular wave, and a sawtooth wave. This control signal has a signal for driving the ultrasonic transducer 11a and a signal for driving the ultrasonic transducer 11b. The frequency of the control signal is preferably the resonance frequency when the driven body 40 is moved at a high speed because the position of the driven body 40 is away from the target position. On the other hand, when the driven body 40 is moved at a reduced speed because the position of the driven body 40 approaches the target position, the non-resonant frequency can be set to a lower frequency as will be described later.

  The control signal output from the vibrator drive control unit 51 b is input to the signal adjustment unit 52. Specifically, the signal adjustment means 52 is an amplifier that performs amplitude amplification (voltage amplification) of the control signal, and the control signal input to the signal adjustment means 52 is necessary for driving the ultrasonic transducers 11a and 11b there. After being amplified to an appropriate voltage, it is output to the ultrasonic transducers 11a and 11b.

  Further, information on the control signal output from the vibrator drive control unit 51 b is also transmitted to the actuator control unit 53. The actuator control means 53 is not shown in its configuration, but is generally an arithmetic circuit that determines whether or not to send a drive signal to the piezoelectric actuator 15 based on the information of the control signal output from the vibrator drive control unit 51b. A signal generation unit that generates a signal for driving the piezoelectric actuator 15 when the arithmetic circuit determines to drive the piezoelectric actuator 15, and an amplifier that boosts the signal generated by the signal generation unit to a predetermined drive voltage And a section.

  When the arithmetic circuit determines that the ultrasonic transducers 11a and 11b are driven at the resonance frequency, the arithmetic circuit does not generate a drive signal for the piezoelectric actuator 15. On the other hand, if it is determined that the ultrasonic transducers 11a and 11b are driven at a non-resonant frequency, the head of the piezoelectric actuator 15 is adapted to the drive frequency and drive voltage waveforms of the ultrasonic transducers 11a and 11b. In order to adjust the position of the 13 friction sliding surfaces, an instruction to generate a drive signal for expanding and contracting the piezoelectric actuator 15 is sent to the signal generating unit provided in the actuator control means 53.

In the moving device 50 configured in this manner, for example, based on an instruction to move the driven body 40 to a predetermined position, the ultrasonic transducers 11a and 11b are first driven at the resonance frequency. That is, a voltage having a resonance frequency of V ₁ = V ₀ sin 2πft is applied to the piezoelectric plates 23a and 23b, and the voltage V ₂ = V ₀ cos 2πft having a phase shifted by 90 degrees from this voltage V ₁ is applied to the piezoelectric plate of the ultrasonic transducer 11b. Applied to 23a 'and 23b'. As a result, the frictional sliding surface of the head 13 moves elliptically, thrust is applied to the driven body 40, and the driven body 40 can be moved at high speed. As described above, when the ultrasonic transducers 11a and 11b are driven at the resonance frequency, the piezoelectric actuator 15 is not driven.

  When the driven body 40 approaches the target position, the drive frequency of the ultrasonic transducers 11a and 11b is lowered to drive the ultrasonic motor 10 in a non-resonant manner. FIG. 3 shows the waveform of the voltage applied to the ultrasonic transducers 11a and 11b and the waveform of the voltage applied to the piezoelectric actuator 15, respectively. Here, a sawtooth wave is used for non-resonant driving of the ultrasonic transducers 11a and 11b, and a rectangular wave is used for driving the piezoelectric actuator 15. The driving voltage A is used for driving the ultrasonic transducer 11a, and the driving voltage B is used for driving the ultrasonic transducer 11b.

  FIG. 4 is an explanatory diagram schematically showing a change in the position of the frictional sliding surface of the head 13 when the ultrasonic motor 10 is driven in a non-resonant manner by the drive signal shown in FIG. In FIG. 4, it is assumed that the ultrasonic transducer 11a is on the -X side and the ultrasonic transducer 11b is on the + X side.

  When the ultrasonic transducers 11a and 11b are respectively moved by the drive voltages A and B shown in FIG. 3, the frictional sliding surface of the head 13 draws a substantially elliptical orbit shown in FIGS. While the voltage for driving the ultrasonic transducer 11a is increasing and the voltage for driving the ultrasonic transducer 11b is decreasing, the piezoelectric actuator 15 is applied in the order of FIG. 4 (a) → (b) → (c). Is applied with a positive voltage (voltage when the piezoelectric actuator 15 is extended), and its length is extended, so that the frictional sliding surface of the head 13 moves on the upper half of this elliptical orbit. . At this time, since the frictional sliding surface of the head 13 is in contact with the driven body 40, it moves to the + X side as the head 13 moves.

  Next, the voltage applied to the piezoelectric actuator 15 is suddenly changed to a negative voltage, and the voltage applied to the ultrasonic transducer 11a is also suddenly dropped to a negative voltage, and the voltage applied to the ultrasonic transducer 11b. Is rapidly increased to a positive voltage. At this time, as shown in FIG. 4D, since the preload mechanism 14 cannot follow the rapid reduction of the piezoelectric actuator 15, the head 13 is separated from the driven body 40 by the reduction of the piezoelectric actuator 15, and The head 13 tends to move to the −X side due to a change in the voltage applied to the acoustic transducers 11a and 11b. As a result, the head 13 instantaneously moves to the −X side through the lower track of the elliptical track of FIG. That is, the head 13 is pulled back to a position where the driven body 40 can be moved again, and returns to the state shown in FIG.

  At this time, since substantially no frictional force acts between the head 13 and the driven body 40, the generation of abnormal noise can be suppressed, and the driven body 40 in the -X direction can be suppressed. Movement can also be suppressed. The time for returning the head 13 to the position where the driven body 40 can be moved is within 50 microseconds (μsec). This is because if the time is longer than this, the preload mechanism 14 follows and presses the head 13 against the driven body 40. In other words, the piezoelectric actuator 15 may be driven so that the head 13 is pulled back within 50 μsec and the head 13 is separated from the driven body 40 during this time.

  Next, as soon as the head X finishes moving to the −X side, a positive voltage is applied to the piezoelectric actuator 15 to expand it. Thereafter, the drive voltage of the ultrasonic transducer 11a is increased, while the drive voltage of the ultrasonic transducer 11b is decreased. Thereafter, by repeating such an operation, the driven body 40 can be moved to the + X side.

  FIG. 5 shows a case where the ultrasonic motor 10 is driven non-resonant by the drive signal shown in FIG. 3 and a case where the ultrasonic transducers 11a and 11b are driven by the drive signal shown in FIG. 6 is a graph showing the moving distance of the driven body 40 when not. As shown in FIG. 5, it was confirmed that when the piezoelectric actuator 15 is driven, the driven body 40 can be moved faster.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to such a form. For example, in the above description, the ultrasonic motor 10 having a structure in which the two ultrasonic transducers 11a and 11b are arranged in a substantially V shape is taken up, but the present invention is not limited to this and is in contact with the driven body. Any ultrasonic motor that causes the head to generate an elliptical motion by resonance driving may be used.

  As an example, there is an ultrasonic motor 70 shown in a side view of FIG. The ultrasonic motor 70 includes piezoelectric elements 71a and 71b that generate expansion / contraction displacement, a holding member 73 that orthogonally arranges the piezoelectric elements 71a and 71b, and a head that connects the piezoelectric elements 71a and 71b and contacts the driven body 40. 72, the piezoelectric actuator 15 which is attached to the holding member 73 and expands and contracts in the direction in which the head 72 is pressed against the driven body 40, and the preload mechanism which is attached to the piezoelectric actuator 15 so as to press the head 72 against the driven body 40. 14.

  The resonance driving of the ultrasonic motor 70 is performed, for example, by driving one of the piezoelectric elements 71a and 71b at the resonance frequency, and thereby an elliptical motion can be generated in the head 83. Further, the non-resonant driving of the ultrasonic motor 70 is performed, for example, by driving the piezoelectric element 71a with the driving voltage A shown in FIG. 3, and simultaneously performing the piezoelectric actuator 15 with the rectangular wave voltage shown in FIG. Thereby, it is possible to cause the head 72 to move substantially the same as the head 13 shown in FIG.

  Another example is an ultrasonic motor 80 shown in the side view of FIG. The ultrasonic motor 80 includes one rectangular piezoelectric plate 81, four drive electrodes 82 a to 82 d formed on the surface of the piezoelectric plate 81 so as to be divided vertically and horizontally, and a back surface of the piezoelectric plate 81. A common electrode (not shown) provided, a head 83 provided at the center of the short side of the piezoelectric plate 81 and abutting against a driven body (not shown), and pressing the head 83 against the driven body 40 The piezoelectric actuator 15 that expands and contracts in the direction and the preload mechanism 14 attached to the piezoelectric actuator 15 so as to press the head 83 against the driven body 40 are provided.

  In this ultrasonic motor 80, the four drive electrodes 82a to 82d are connected to form two sets of electrodes. Resonant driving of the ultrasonic motor 80 is performed by applying a driving voltage whose phase is shifted by 90 degrees to each group, and thereby the elliptical motion can be generated in the head 83. The non-resonant driving of the ultrasonic motor 80 can be performed, for example, with the driving voltages A and B previously shown in FIG. 3, and this causes the head 83 to move substantially the same as the head 13 shown in FIG. Can be generated.

  As another example, there is a flat-type ultrasonic motor (hereinafter referred to as “L1B4 type motor”) 90 having a deformed degenerated vertical L1-horizontal B4 mode shown in the sectional view of FIG. The L1B4 type motor 90 includes a rectangular elastic body 93, two piezoelectric elements 94a to 94d attached to the front and back surfaces of the elastic body 93, and a protrusion that transmits vibration generated in the elastic body 93 to the driven body 40. 95. Further, since the center of the elastic body 93 in the longitudinal direction is a node of vibration and is not displaced, the piezoelectric actuator 15 is attached to this portion, and the preload mechanism 14 is further attached to the piezoelectric actuator 15 to drive the protrusion 95. It is pressed against the body 40.

  The piezoelectric elements 94a to 94d are generally single plate type piezoelectric elements in which electrodes (not shown) are formed on the front and back surfaces of a piezoelectric body. One set of piezoelectric elements 94a and 94d and one set of piezoelectric elements 94b and 94c are used as two sets of drive electrodes. Resonant driving of the ultrasonic motor 90 is performed by applying a driving voltage whose phase is shifted by 90 degrees to each pair of driving electrodes, thereby causing the elastic body 93 to have a first-order stretching resonance and a fourth-order bending in the longitudinal direction. Resonance occurs at the same time, and the movements are combined and transmitted to the protrusion 95, and an elliptical motion is generated at the tip of the protrusion 95. The non-resonant driving of the ultrasonic motor 90 can be performed, for example, with the driving voltages A and B previously shown in FIG. 3, and at this time, the protrusion 95 moves substantially the same as the head 13 shown in FIG. Can be generated.

  In the present invention, the actuator provided in the ultrasonic motor for adjusting the position of the head in the pressing direction of the head by the preload mechanism is not limited to that using the piezoelectric effect, and depends on the follow-up speed of the preload mechanism. For example, an electromagnetic actuator can also be used.

  The ultrasonic motor, the moving device, and the driving method thereof according to the present invention are suitable for an XY stage device mounted on a semiconductor manufacturing apparatus or the like and a driving method thereof.

Sectional drawing which shows schematic structure of the ultrasonic motor which concerns on this invention. Explanatory drawing which shows the structure of the moving apparatus provided with the ultrasonic motor shown in FIG. FIG. 2 is an explanatory diagram showing a driving voltage waveform of an ultrasonic transducer and a driving voltage waveform of a piezoelectric actuator included in the ultrasonic motor shown in FIG. 1. FIG. 4 is an explanatory diagram schematically showing a change in the position of the frictional sliding surface of the head when the ultrasonic motor is non-resonantly driven with the driving voltage shown in FIG. 3. Explanatory drawing which shows the relationship between the presence or absence of the drive of a piezoelectric actuator at the time of the nonresonant drive of an ultrasonic motor, and the moving distance of a to-be-driven body. The side view which shows schematic structure of another ultrasonic motor. Furthermore, the side view which shows schematic structure of another ultrasonic motor. Furthermore, sectional drawing which shows schematic structure of another ultrasonic motor. Explanatory drawing which shows schematic structure of a well-known ultrasonic motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10; Ultrasonic motor 11a * 11b; Ultrasonic vibrator 12; Holding member 13; Head 13a; Contact part 13b * 13b '; Connecting part 13c * 13c'; Neck part 14; Preload mechanism 14a; 14c; Frame 15; Piezoelectric actuators 21 and 21 '; Bolts 22 and 22'; Cap nuts 23a, 23b, 23a 'and 23b'; Piezoelectric plates 24a to 24c; 24a 'to 24c'; Electrode plate 40; Position sensor 50; Moving device 51; Vibrator control means 51a; Instruction value generation unit 51b; Vibrator drive control unit 52; Signal adjustment means 53; Actuator control means 55; Motor drive control device 70/80/90; Motors 71a and 71b; Piezoelectric elements 72 and 83; Head 73; Holding member 81; Piezoelectric plates 82a to 82d; Drive electrode 9 3; elastic body 94a to 94d; piezoelectric element 95; projection body 100; ultrasonic motor 101; driven body 111a and 111b; ultrasonic vibrator 112; holding member 113; head 114; preload mechanism 115a and 115b;

Claims (6)

An ultrasonic motor that frictionally drives a driven body,
An ultrasonic transducer,
A friction sliding portion that contacts the driven body and is displaced by driving the ultrasonic vibrator;
A retractable actuator that controls the position of the friction sliding portion in a direction in which the friction sliding portion is pressed against the driven body when the ultrasonic vibrator is driven in a non-resonant manner;
An ultrasonic motor comprising: Two ultrasonic transducers having a Langevin type structure including a piezoelectric element are provided,
The frictional sliding portion has a substantially V-shaped shape so that the vertex is in contact with the driven body and the two ultrasonic transducers are connected to the end portions thereof,
The ultrasonic motor further includes a holding member that holds the two ultrasonic transducers at a predetermined angle,
The ultrasonic motor according to claim 1, wherein the actuator is attached to the holding member. A moving device that moves the driven body by frictionally driving the driven body with an ultrasonic motor,
The ultrasonic motor includes an ultrasonic vibrator, a friction sliding portion that is in contact with the driven body and is displaced by driving the ultrasonic vibrator, and the friction sliding portion is moved with a constant force. A preload mechanism that presses against the drive body, and an actuator that is displaceable in a direction in which the preload mechanism presses the friction sliding portion,
A moving device comprising: an actuator control device that drives the actuator to control the position of the frictional sliding portion when the ultrasonic motor is driven in a non-resonant manner. The ultrasonic motor is
Two Langevin type ultrasonic transducers with piezoelectric elements;
A holding member for holding the two ultrasonic transducers at a predetermined angle;
A frictional sliding portion having a substantially V-shaped shape, in contact with the driven body at an apex portion thereof, and connected to the two ultrasonic vibrators at an end portion thereof;
The moving apparatus according to claim 3, further comprising: A method for driving a moving device according to claim 3,
When the friction sliding portion is moved in the opposite direction with respect to the direction in which the driven body is frictionally moved to pull back the friction sliding portion, the friction sliding portion and the driven body are substantially separated from each other. A method for driving a moving device, wherein the actuator is displaced as described above. When the direction in which the friction sliding portion moves is the same as the direction in which the driven body is moved, the actuator is adjusted so that the frictional force applied to the driven body from the friction sliding portion is increased. Stretch and
When the direction of movement of the friction sliding portion is opposite to the direction of movement of the driven body to pull back the friction sliding portion, the driven body and the friction sliding portion are substantially The method of driving a moving device according to claim 5, wherein the actuator is contracted so as to be separated from each other.

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