JP2010279152A - Ultrasonic motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor drive device (XY stage) of which operation is stabilized by maintaining a press applied to an ultrasonic vibrator constant even if adding a mounted article to a body to be driven. <P>SOLUTION: The ultrasonic motor drive device includes a plurality of ultrasonic vibrators that simultaneously excite longitudinal vibration and bending vibration to generate an elliptical vibration, and use the elliptical vibration as a driving force to drive the body to be driven. The ultrasonic motor drive device includes a driving element that is provided in each ultrasonic vibrator so that the driving element opposes the body to be driven, abuts on the body to be driven, and drives the body to be driven in an arbitrary direction in a plane, a press detection unit for detecting a press operating between the body to be driven and the ultrasonic vibrator and a press adjustment unit for adjusting press to prescribed press, based on results detected by the press detection unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor driving device.

  An ultrasonic motor that applies a voltage to a vibrating body having an ultrasonic vibrator to vibrate and frictionally drives a moving body (hereinafter referred to as a driven body) in contact with the vibration is a precision positioning device or digital It has recently attracted attention as a driving source for cameras and the like, and further applications are expected.

  For example, in the piezoelectric actuator described in Patent Document 1, two piezoelectric driving bodies 901a and 901b (ultrasonic transducers) are arranged in parallel with each other as shown in FIG. The contact portion with the driven body 904 is configured to come. Here, FIG. 7 is a side view showing a configuration of a conventional piezoelectric actuator.

  As shown in FIG. 8, a plurality of the piezoelectric actuators are arranged as driving bodies 911a, 911b, 911c, and 911d, and can drive one driven body 904. The pressing force from the driving bodies 911a, 911b, 911c, and 911d to the driven body 904 uses the weight of the driven body 904 on the driving bodies 911a, 911b, 911c, and 911d. Here, FIG. 8A is a plan view showing a configuration of a conventional piezoelectric actuator, and FIG. 8B is a side view of FIG.

  According to the configuration shown in FIG. 8, the driven body 904 is placed on the driving bodies 911a, 911b, 911c, and 911d as four ultrasonic motors, and driven in the XY plane by always contacting them. It is an XY stage on which the body 904 moves.

JP 2004-242493 A

  However, since the pressing force applied to the ultrasonic vibrator is given by the weight of the driven body, if a load is added on the driven body, the pressing force applied to the ultrasonic vibrator inevitably increases. When the driven body is driven in this state, the pressing force applied to the ultrasonic transducer varies due to a change in the positional relationship between the mounted object and the ultrasonic transducer. Furthermore, the pressing force is higher than the predetermined pressing force due to the addition of the load. As a result, there is a possibility that the generated force of the ultrasonic vibrator is defeated by the weight of the driven body and the mounted object, and the amount of movement varies.

  The present invention has been made in view of the above, and even when a mounted object is added to a driven body, it is possible to keep the pressing force applied to the ultrasonic vibrator constant, and this stabilizes the operation. An object is to provide an ultrasonic motor driving device (XY stage).

  In order to solve the above-described problems and achieve the object, an ultrasonic motor driving device according to the present invention generates an elliptical vibration by simultaneously exciting a longitudinal vibration and a bending vibration and uses the elliptical vibration as a driving force to be driven. An ultrasonic motor driving device having a plurality of ultrasonic vibrators, which is provided on the ultrasonic vibrator so as to face the driven body, and is in contact with the driven body so that the driven body is in a plane. A driver that is driven in an arbitrary direction, a pressing force detection unit that detects a pressing force acting between the driven body and the ultrasonic transducer, and a predetermined pressing force based on a detection result by the pressing force detection unit. And a pressing force adjusting unit that adjusts the pressure.

  In the ultrasonic motor driving device according to the present invention, it is preferable that the pressing force adjusting unit and the driven body are not mechanically connected.

  In the ultrasonic motor driving device according to the present invention, when the pressing force detecting unit detects that the pressing force acting between the driven body and the ultrasonic transducer is larger than the predetermined pressing force, It is preferable that the pressure adjusting unit acts so as to reduce the increased pressing force.

  In the ultrasonic motor driving device according to the present invention, when the pressing force detection unit detects that the pressing force acting between the driven body and the ultrasonic transducer is smaller than the predetermined pressing force, It is preferable that the pressure adjusting unit acts to increase the pressing force corresponding to the decrease.

  In the ultrasonic motor driving apparatus according to the present invention, an elliptical vibration is generated on the driver by applying a two-phase alternating signal that excites the longitudinal primary resonance mode and the bending secondary resonance mode to the ultrasonic transducer. It is preferable to further include a control unit that monitors the detection value of the pressing force detection unit at a predetermined interval and controls the pressing force adjustment unit based on the calculation result of the detection value and the predetermined pressing force.

  In the ultrasonic motor driving device according to the present invention, it is preferable that at least one pressing force adjusting unit is disposed on the base member.

  In the ultrasonic motor driving device according to the present invention, it is preferable that the pressing force detection unit is disposed between the base member and the driven body.

  In the ultrasonic motor driving device according to the present invention, the pressing force adjusting unit has an air discharge head and a suction head provided on the base member, and controls the discharge pressure of the air discharge head and the suction pressure of the suction head by the control unit. It is preferable to adjust the pressing force by the control.

  In the ultrasonic motor driving device according to the present invention, the pressing force adjusting unit includes a permanent magnet provided on the driven body and a magnetic coil provided on the base member, and the magnetic coil and permanent magnet by the control unit. It is preferable to adjust the pressing force by controlling the magnetic force between them.

  The ultrasonic motor driving device according to the present invention has at least a pair of ultrasonic vibrators with respect to two axes in the displacement plane of the driven body, and the driven body is supported by a driver of the ultrasonic vibrator. Preferably it is.

  The ultrasonic motor driving device according to the present invention makes it possible to keep the pressing force applied to the ultrasonic vibrator constant even when a mounted object is added to the driven body, and thereby the ultrasonic motor driving with stable operation. There is an effect that an apparatus (XY stage) can be provided.

It is a perspective view which shows the structure of the ultrasonic motor drive device which concerns on 1st Embodiment of this invention. 1 is a perspective view showing a configuration of an ultrasonic transducer according to a first embodiment of the present invention. It is a control block diagram of the ultrasonic motor drive device concerning a 1st embodiment of the present invention. It is a perspective view which shows the structure of the ultrasonic motor drive device which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the structure of the ultrasonic motor drive device which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the structure of the ultrasonic motor drive device which concerns on 4th Embodiment of this invention. It is a side view which shows the structure of the conventional piezoelectric actuator. (A) is a top view which shows the structure of the conventional piezoelectric actuator, (b) is a side view of (a).

  Hereinafter, an embodiment of an ultrasonic motor driving device according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment.

(First embodiment)
The ultrasonic motor driving device according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view showing a configuration of an ultrasonic motor driving apparatus 100 according to the first embodiment. FIG. 2 is a perspective view showing the configuration of the ultrasonic transducer 120 according to the first embodiment. FIG. 3 is a control block diagram of the ultrasonic motor driving apparatus 100 according to the first embodiment.

  As shown in FIG. 1, the ultrasonic motor driving apparatus 100 includes an ultrasonic vibrator 120, driver elements 122 and 123, a pressing force detection unit 130, and a pressing force adjustment unit 140. Furthermore, the ultrasonic motor driving apparatus 100 includes a base member 150, a fixing member 160, a position detector 170 (FIG. 3), and a control unit 180 (FIG. 3).

In the ultrasonic transducer 120, two pairs facing each other are arranged on a plate-like base member 150 provided on the fixing member 160. Each of the four ultrasonic vibrators 120 excites longitudinal vibration and bending vibration simultaneously to generate elliptical vibration, and freely drives the driven body M in the two-dimensional plane using the elliptical vibration as a driving force. The elliptical vibration is generated on the driver elements 122 and 123 by applying a two-phase alternating signal that excites the longitudinal primary resonance mode and the bending secondary resonance mode to the ultrasonic vibrator 120.
Note that it is preferable that at least one pair of the ultrasonic transducers 120 is provided with respect to the two axes in the displacement plane of the driven body M.

  The operation of the ultrasonic transducer 120 is controlled by the control unit 180 (FIG. 3). The control unit 180 monitors the detection value of the pressing force detection unit 130 at predetermined intervals, and controls the pressing force adjustment unit 140 based on the calculation result of the detection value and the predetermined pressing force.

As shown in FIG. 2, the ultrasonic vibrator 120 includes a piezoelectric element 121, driver elements 122 and 123, a piezoelectric element holder 124, a vibrator holder 125, and a housing portion 126.
The driver elements 122 and 123 are formed on the upper surface of the piezoelectric element 121 so as to face and come into contact with the driven body M, and drive the driven body M in an arbitrary direction within the two-dimensional plane by driving the piezoelectric element 121. The driver elements 122 and 123 are arranged corresponding to the vibration antinodes or the vicinity of the antinodes. Three or more driver elements may be provided.

  Piezoelectric element holders 124 are respectively formed at the lower portions of the two opposing side surfaces of the piezoelectric element 121. The piezoelectric element holder 124 is provided with a pair of protrusions 124 a that protrude outwardly at positions corresponding to the common node or the vicinity of the node of the longitudinal vibration and bending vibration of the piezoelectric element 121.

  On the other hand, a long plate-like vibrator holder 125 is fixed to the base member 150, and a pair of accommodating portions 126 extending upward (in the pressing axis direction) from opposite long sides on the upper surface of the vibrator holder 125. Are arranged opposite to each other. On the vibrator holder 125, the piezoelectric element holder 124 is placed so as to be sandwiched between the accommodating portions 126. The accommodating portion 126 is composed of two plate-like members extending upward in parallel with each other, and the protruding portion 124a of the piezoelectric element holder 124 is inserted between the plate-like members. By inserting the protruding portion 124a into the housing portion 126, the protruding portion 124a can move only in the direction of the pressing axis, and the piezoelectric element 121 is restricted from moving in the width direction.

In each of the four ultrasonic transducers 120, the pressing force detection unit 130 is disposed at a position corresponding to an intermediate position between the two accommodating units 126 on the upper surface of the transducer holder 125. A pressing force applied to the sonic transducer 120 is detected. This pressing force can be detected as the magnitude of distortion generated in the vibrator holder 125 by the force transmitted from the piezoelectric element holder 124 to the housing portion 126. The detection result is output to the control unit 180 (FIG. 3). The pressing force detection unit 130 includes, for example, a strain gauge, a load cell, and a piezoelectric pressure sensor.
The pressing force detection unit 130 can be disposed at any position as long as the pressing force applied to the ultrasonic transducer 120 can be monitored between the base member 150 and the driven body M. Moreover, it is preferable that the pressing force detection part 130 is urged | biased upwards by the pressing member (for example, spring) not shown.

  The pressing force adjustment unit 140 includes a discharge head 141 and a suction head 142. The ejection head 141 and the suction head 142 are both provided on the base member 150, and their operations are controlled by the control unit 180 (FIG. 3). The discharge head 141 discharges air toward the upper driven body M at a predetermined discharge pressure. The suction head 142 sucks the upper driven body M with a predetermined suction pressure.

  The ejection head 141 and the suction head 142 are not mechanically connected to the driven body M. In the initial state where nothing is mounted on the driven body M, that is, in the state where the pressing force applied to the ultrasonic transducer 120 is a predetermined pressing force, the driven body M has four ultrasonic transducers 120 respectively. The driving elements 122 and 123 are preferably in contact with the ejection head 141 and the suction head 142.

  The position detector 170 detects the relative movement amount of the driven body M with respect to the base member 150. The detection result is output to the control unit 180 (FIG. 3). The position detector 170 includes, for example, an optical encoder, a laser length measuring device, and a Hall element.

Subsequently, the operation of the ultrasonic motor driving apparatus 100 will be described in detail.
First, when the driven bodies M are placed on the four ultrasonic vibrators 120, an optimum pressing force is applied to each ultrasonic vibrator 120 by the dead weight of the driven bodies M. However, for example, in a state where a mounted object is placed on the driven body M, a state where the ultrasonic motor driving device 100 is installed obliquely, and a state where the entire ultrasonic motor driving device 100 is turned over and used, ultrasonic waves are used. The pressing force applied to the vibrator 120 varies.

  In contrast, in the ultrasonic motor driving apparatus 100, the pressing force detection unit 130 directly monitors the pressing force applied to the ultrasonic transducer 120, and the control unit 180 displays the detection result by the pressing force detection unit 130. A process for comparing with the optimum pressing force (predetermined pressing force) is performed. The value of the predetermined pressing force is stored in advance in the storage unit of the control unit 180. As the comparison process, for example, there are a method of individually comparing each detected value and the initial value, and a method of comparing the average value of the detected values and the initial value.

  The control unit 180 drives the ejection head 141 and the suction head 142 of the pressing force adjustment unit 140 according to the result of the comparison process.

  Specifically, when the detection value (or average value) detected by the pressing force detection unit 130 is larger than the initial value (predetermined pressure), air is discharged from the discharge head 141 at a discharge pressure corresponding to an increase relative to the initial value, The driven body M is lifted to reduce the pressing force so that the detected value substantially coincides with the initial value.

  On the other hand, when the detected value is smaller than the initial value, air is sucked from the suction head 142 with a negative pressure corresponding to a decrease with respect to the initial value, the driven body M is sucked and the pressing force is increased, and the detected value and the initial value are increased. Are in a state that almost matches.

  With the above operation, the pressing force applied to the ultrasonic transducer 120 can be adjusted to the initial value.

  According to the above configuration, the ultrasonic vibrator is caused by the variation in the pressing force due to the operation of the driven body M, the variation in the pressing force due to the change of the load on the driven body M, or the variation in the pressing force due to the inclination of the apparatus. The pressing force applied to 120 can always be kept constant. Accordingly, a constant pressing force can always be applied to the ultrasonic vibrator 120 regardless of the state of the apparatus, the driven body M, and the mounted object, and thus stable driving is possible.

  Further, as shown in FIG. 1, since all the constituent members such as the pressing force detection unit 130 and the pressing force adjustment unit 140 can be arranged on the lower surface side of the driven body M, a wide work area on the upper surface of the driven body M can be secured. , User convenience is improved.

(Second Embodiment)
The ultrasonic motor driving apparatus according to the second embodiment is different from the ultrasonic motor driving apparatus according to the first embodiment in that a plurality of pressing force adjustment units 240 are provided on the base member 150. Other configurations are the same as those of the first embodiment, and the same reference numerals are used for the same members.

  FIG. 4 is a perspective view showing a configuration of an ultrasonic motor driving apparatus 200 according to the second embodiment. The pressing force adjustment unit 240 includes a discharge head 241 and a suction head 242, respectively. In the example shown in FIG. 4, the same number of pressing force adjustment units 240 as that of the ultrasonic transducers 120 are arranged. Further, each pressing force adjustment unit 240 is provided at a position corresponding to each ultrasonic transducer 120. That is, the ultrasonic transducers 120 are arranged uniformly at the approximate center of each side of the base member 150 that is rectangular in plan view, and the pressing force adjusting units 240 are arranged between the adjacent ultrasonic transducers 120.

  When the pressing force adjustment unit 240 is arranged in this way, the pressing force applied to each ultrasonic transducer 120 is individually monitored by the corresponding pressing force detection unit 130, and the variation is near the ultrasonic transducer 120. It is possible to adjust to the initial pressing force by driving one or two of the pressing force adjusting units 240 installed in.

  For example, when a load is mounted on the upper surface on the side M4 side of the substantially rectangular driven body M having four sides M1, M2, M3, and M4, the pressing force applied by the ultrasonic transducer 120 corresponding to each side The ultrasonic transducer 120 corresponding to the side M4 is larger than the ultrasonic transducer 120 corresponding to the side M1, and the ultrasonic transducer 120 corresponding to the side M3 is ultrasonic vibration corresponding to the side M2. Larger than child 120. Therefore, in the ultrasonic transducer 120 corresponding to the side M4, the pressing force is larger than the initial pressing force (predetermined pressing force) before the load is mounted on the driven body M, and corresponds to the side M2. In the ultrasonic transducer 120, the pressing force is smaller than a predetermined pressing force.

  In this case, in the pressing force adjustment unit 240 on both sides of the ultrasonic transducer 120 corresponding to the side M4, since the pressing force of the ultrasonic transducer 120 is larger than the initial value, the ejection head is set at a predetermined ejection pressure. An operation is performed to discharge the air from the driven body 241 to the driven body M side and to float the driven body M. As a result, the increased pressing force can be reduced.

  On the other hand, the pressing force adjusting unit 240 on both sides of the ultrasonic transducer 120 corresponding to the side M2 has the suction head 242 at a predetermined negative pressure because the pressing force of the ultrasonic transducer 120 is smaller than the initial value. The operation of sucking air and sucking the driven body M is performed. Thereby, the pressing force for the decrease can be increased.

By the above two operations, it is possible to adjust the pressing force applied to each ultrasonic transducer 120 to the initial value.
Note that five pressing force adjustment units 240 may be provided on the base member 150. Other configurations, operations, and effects are the same as those in the first embodiment.

(Third embodiment)
In the ultrasonic motor driving device according to the third embodiment, a pressing force adjustment unit 340 including a permanent magnet 341 and a magnetic coil 342 is used instead of the pressing force adjustment unit 140 of the first embodiment. Other configurations are the same as those of the ultrasonic motor driving apparatus 100 according to the first embodiment, and the same reference numerals are used for the same members.

FIG. 5 is a perspective view showing a configuration of an ultrasonic motor driving device 300 according to the third embodiment.
The pressing force adjusting unit 340 includes a permanent magnet 341 disposed inside the driven body M, and a magnetic coil 342 disposed substantially at the center of the upper surface of the base member 150. A predetermined amount of current is applied to the magnetic coil 342 in accordance with an instruction from the control unit 180. Since the direction of the magnetic field generated can be changed depending on the direction of the current flowing through the magnetic coil 342, the driven member M is attracted to the base member 150 side by the magnetic attraction between the permanent magnet 341 and the magnetic coil 342, or is permanently The driven member M can be separated from the base member 150 by being repelled by a magnetic repulsive force between the magnet 341 and the magnetic coil 342. As a result, as in the first embodiment and the second embodiment, it is possible to adjust the pressing force between the driven body M and the ultrasonic transducer 120 to a predetermined pressing force.

Although only one permanent magnet 341 is arranged inside the driven body M, it may be arranged separately. Further, a magnetic coil may be disposed on the driven body M side, and a permanent magnet may be disposed on the base member 150 side.
Further, the strength of the magnetic field between the permanent magnet 341 and the magnetic coil 342 is inversely proportional to the total length of the magnetic coil 342 and is proportional to the number of turns of the magnetic coil 342 and the current. Therefore, if the number of turns and the total length are fixed, the magnetic field generated by increasing the value of the current flowing through the magnetic coil 342 can be increased.
In addition, about another structure, an effect | action, and an effect, it is the same as that of 1st Embodiment.

(Fourth embodiment)
The ultrasonic motor driving apparatus according to the fourth embodiment differs from the ultrasonic motor driving apparatus 300 according to the third embodiment in that a plurality of magnetic coils 342 of the pressing force adjusting unit 340 are provided on the base member 150. . Other configurations are the same as those of the ultrasonic motor driving apparatus 300 according to the third embodiment, and the same reference numerals are used for the same members.

FIG. 6 is a perspective view showing the configuration of the ultrasonic motor driving device according to the fourth embodiment.
The magnetic coils 342 are arranged at approximately five locations at approximately the center and four corners of the base member 150 that is substantially rectangular in plan view.
When the magnetic coils 342 are arranged in this way, the pressing force applied to each ultrasonic transducer 120 is individually monitored by the corresponding pressing force detection unit 130, and the variation is installed near the ultrasonic transducer 120. By driving one to three of the magnetic coils 342, the pressing force can be adjusted to the initial value.

  Specifically, when a large load is applied to a part of the driven body M and the driven body M is tilted, a portion where the pressing force of the ultrasonic transducer 120 is larger than the initial value is a permanent magnet. An operation is performed in which the driven body M is lifted by a magnetic repulsive force between the magnetic coil 341 and the magnetic coil 342. As a result, the increased pressing force can be reduced. On the other hand, in the portion where the pressing force of the ultrasonic transducer 120 is smaller than the initial value, the operation of attracting the driven body M by the magnetic attraction between the permanent magnet 341 and the magnetic coil 342 is performed. I do. Thereby, the pressing force for the decrease can be increased.

By the above two operations, it is possible to adjust the pressing force applied to each ultrasonic transducer 120 to the initial value.
In addition, about another structure, an effect | action, and an effect, it is the same as that of 3rd Embodiment.

  As described above, the ultrasonic motor driving device according to the present invention is suitable for highly accurate driving of small equipment.

DESCRIPTION OF SYMBOLS 100 Ultrasonic motor drive device 120 Ultrasonic vibrator 121 Piezoelectric element 122, 123 Driver 124 Piezoelectric element holder 124a Protrusion part 125 Vibrator holder 126 Storage part 130 Pressure detection part 140 Pressure adjustment part 141 Discharge head 142 Adsorption head 150 Base member 160 Fixed member 170 Position detector 180 Control unit 200 Ultrasonic motor driving device 240 Pressing force adjusting unit 241 Discharge head 242 Adsorption head 300 Ultrasonic motor driving device 340 Pressing force adjusting unit 341 Permanent magnet 342 Magnetic coil M Driven body

Claims (10)

An ultrasonic motor driving device having a plurality of ultrasonic vibrators that simultaneously drive longitudinal vibration and bending vibration to generate elliptical vibration and drive a driven body using the elliptical vibration as a driving force,
A driver that is provided in the ultrasonic transducer so as to face the driven body, contacts the driven body, and drives the driven body in an arbitrary direction in a plane;
A pressing force detection unit that detects a pressing force acting between the driven body and the ultrasonic transducer;
A pressing force adjusting unit that adjusts the pressing force to a predetermined pressing force based on a detection result by the pressing force detecting unit;
An ultrasonic motor driving device comprising:   The ultrasonic motor driving apparatus according to claim 1, wherein the pressing force adjusting unit and the driven body are not mechanically connected.   When the pressing force detection unit detects that the pressing force acting between the driven body and the ultrasonic transducer is larger than the predetermined pressing force, the pressing force adjustment unit increases. The ultrasonic motor driving device according to claim 1, wherein the ultrasonic motor driving device acts to reduce the pressing force of the minute.   When the pressing force detection unit detects that the pressing force acting between the driven body and the ultrasonic transducer is smaller than the predetermined pressing force, the pressing force adjustment unit decreases The ultrasonic motor driving device according to claim 1, wherein the ultrasonic motor driving device acts to increase the pressing force of the minute. Applying an alternating signal of two phases that excites a longitudinal primary resonance mode and a bending secondary resonance mode to the ultrasonic vibrator to generate elliptical vibration on the driver;
It further comprises a control unit that monitors a detection value of the pressing force detection unit at a predetermined interval and controls the pressing force adjustment unit based on a calculation result of the detection value and the predetermined pressing force. The ultrasonic motor drive device according to claim 3 or 4.   The ultrasonic motor driving apparatus according to claim 5, wherein at least one pressing force adjusting unit is disposed on a base member.   The ultrasonic motor driving apparatus according to claim 6, wherein the pressing force detection unit is disposed between the base member and the driven body.   The pressing force adjusting unit includes an air discharge head and a suction head provided on the base member, and the control unit controls the discharge pressure of the air discharge head and the suction pressure of the suction head by the control unit. The ultrasonic motor driving apparatus according to claim 7, wherein adjustment is performed.   The pressing force adjusting unit includes a permanent magnet provided on the driven body and a magnetic coil provided on the base member, and a magnetic force between the magnetic coil and the permanent magnet by the control unit. The ultrasonic motor driving apparatus according to claim 7, wherein the pressing force is adjusted by the control.   It has at least a pair of the ultrasonic vibrators with respect to two axes in a displacement plane of the driven body, and the driven body is supported by the driver of the ultrasonic vibrator. The ultrasonic motor drive device according to claim 1.

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