JP2005218243A - Ultrasonic motor and electronic apparatus with ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor in which a vibration member is supported without suppressing vibration and a high output is attained by applying the vibration member to a moving body by a high pressing force. <P>SOLUTION: In the ultrasonic motor, a multilayer piezoelectric element constituted of sintering piezoelectric elements 11a, 11b, 12a, 12b, and 13 integrally serves as an oscillation member 10, a hole 20 is formed in the oscillation member 10, and the oscillation member 10 is supported by a supporting member 40 connected with the hole 20. By such an arrangement, the oscillation member 10 and the supporting member 40 can be integrated at high strength, the oscillation member 10 can be applied to a moving body stably by a high pressing force, the piezoelectric element can be supported without weakening vibration, stabilized high output driving can be attained, and not only vibration energy but also electric energy can be utilized with high efficiency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic motor configured to support and pressurize a rectangular periodic vibration member with respect to a movable body, and an electronic apparatus including the same.

  In recent years, an ultrasonic driving device using a stretching vibration and a bending vibration (double mode vibrator) of a rectangular piezoelectric diaphragm is expected to be applied to various applications. Such an ultrasonic drive device can move the moving body linearly or rotationally by combining two different vibration modes and displacing the piezoelectric diaphragm. As an example, an ultrasonic motor 7000 using a rectangular vibrator is shown in FIG. 8 (see Patent Document 1). This apparatus includes a piezoelectric element 711 composed of a multilayer piezoelectric body, a vibrating body 710 bonded to the piezoelectric element 711, a columnar support member 740 that is locked to a vibration node of the vibrating body 710, The projection 730 is fixed to the lower side of the vibrating body 710, and the movable body (not shown) is in contact with the projection 730.

  According to this conventional ultrasonic drive device, expansion and contraction vibration and bending vibration are generated in the vibrating body 710 by the expansion and contraction of the piezoelectric element 711 to which an electric signal is applied. From the combination of both of these movements, the protrusion 730 moves elliptically, and the moving body in contact with the protrusion 730 linearly moves in a certain direction.

  However, according to the ultrasonic motor 7000, since the piezoelectric element 711 is locked to the vibrating body 710, the deformation of the piezoelectric element 711 is transmitted to the vibrating body 710, causing the vibrating body 710 to be deformed. become. Accordingly, the deformation of the piezoelectric element 711 does not directly deform the vibrating body 710, and a loss occurs in this transmission process. In addition, since the proportion of the piezoelectric element 711 in the vibrating body 710 is small, the output of the ultrasonic motor 7000 is small.

Therefore, by making the laminated piezoelectric element itself sintered together as a vibrating body, the entire vibrating body can be used as a driving source, and the loss in the transmission process can be reduced to achieve high efficiency and high output. A motor has been developed (see Patent Document 2).
Japanese Patent Laid-Open No. 06-327275 JP 2000-116162 A

  However, in order to obtain a high driving force, the conventional ultrasonic motor using the integrally sintered laminated piezoelectric element itself as a vibrating body needs to reliably support the laminated piezoelectric element.

  Therefore, the present invention is to obtain a high output by bringing the vibrator into contact with the moving body with a high pressing force while reliably supporting the vibrating body made of the laminated piezoelectric element without suppressing the vibration. It is an object of the present invention to provide an ultrasonic motor and an electronic device with an ultrasonic motor that are made possible.

  In order to solve the above-described problems, the ultrasonic motor according to the present invention includes a laminated piezoelectric element that is integrally sintered as a vibrating body, and includes a hole formed in the laminated piezoelectric element and a support member that is connected to the hole. According to this, since the laminated piezoelectric element and the support member can be integrated with high strength, the vibrating body can be brought into contact with the moving body with a stable and high pressure. For this reason, the ultrasonic motor can be driven stably and with high output.

  Further, by providing the hole in a portion that does not affect the vibration of the piezoelectric element (vibration node), the hole can be supported without hindering the vibration of the piezoelectric element. Therefore, it is possible to use vibration energy and thus electric energy with high efficiency. In particular, if a hole is provided in a portion of the laminated piezoelectric element where the strain of the vibration mode to be excited is small, the vibration excitation force is not weakened. Specifically, in an ultrasonic motor using stretching vibration and bending vibration, the distortion of the vibration mode is reduced in the longitudinal direction and the center in the width direction of the piezoelectric element that excites bending vibration. In addition, the electric energy and the excitation force of the piezoelectric element can be used with high efficiency.

  In addition, since the specific electrode group and the support member are electrically connected and a drive signal is supplied to the electrode group via the support member, vibration of the piezoelectric element is inhibited by the energizing means (wires or the like) to the electrode group. Therefore, high-efficiency driving is possible.

  In addition, by using an ultrasonic motor provided with these vibrators as a drive source of an electronic device, the electronic device can be reduced in size, thickness, and power consumption.

  The ultrasonic motor of the present invention includes a laminated piezoelectric element that is integrally sintered as a vibrating body, a hole is provided in a portion that does not contribute to vibration excitation of the laminated piezoelectric element, and a support member that is connected to the hole is configured. Thus, the laminated piezoelectric element and the support member can be integrated with high strength, and the vibrating body can be brought into contact with the moving body with a stable and high pressure. Therefore, stable and high output driving is possible. In addition, a support member is provided in a part that does not contribute to vibration excitation of the laminated piezoelectric element, and the vibration member is supported by this support member, so that it can be used without weakening the vibration of the vibration member, so that the output of the ultrasonic motor is increased. Is possible.

  Further, by adopting a configuration in which the support member and the electrode inside the laminated piezoelectric element are electrically connected, the device configuration can be simplified, downsized, and lead wires can be easily reduced. And it becomes possible to utilize electrical energy with high efficiency.

  In addition, by using these ultrasonic motors as a drive source of an electronic device, the electronic device can be reduced in size, thickness, and power consumption.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment.

(Embodiment 1)
FIG. 1 is a diagram illustrating an ultrasonic motor 1000 according to the present invention. 1A is a perspective view of the ultrasonic motor 1000, and FIG. 1B is a cross-sectional view taken along a cross-section A shown in FIG. FIG. 2 is a diagram for explaining the vibration amplitude of the vibration member 10. 3A and 3B are diagrams illustrating a specific structure, polarization direction, and electrode arrangement of the vibration member 10, FIG. 3A is a perspective view of the vibration member 10, and FIG. 3B is a specific view of the vibration member 10. It is a figure explaining typical structure, a polarization direction, and arrangement | positioning of an electrode.

  The ultrasonic motor 1000 includes a rectangular vibration member 10 formed by laminating a plurality of piezoelectric elements 11a, 11b, 12a, 12b, and 13, a hole 20 and a protrusion 30 provided in the vibration member 10, a hole, It is comprised from the support member 40 connected to 20 by means, such as adhesion | attachment, driving, fitting, and joining. Further, a moving body 60 whose moving direction is defined by the guide member 50 is provided under the protrusion 30, and the protrusion 30 is in pressure contact with the moving body 60 by the pressure member 70 engaged with the support member 40. It has a configuration. In FIG. 1, the support method and the pressurization method are illustrated in a simplified manner. However, in the member engaged with the support member 40, the vibration member 10 is restricted from moving in the moving direction of the moving body 60 and is vibrated. If the pressure is applied to the support member 40 so that the contact pressure is generated between the member 10 and the moving body 60, the method is not limited. In addition, in FIG. 1B, a gap is formed at the bottom of the hole 20 and the support member 40 is connected. However, even if connected without a gap, the function is possible.

  Next, the vibration member 10 which explains the vibration of the vibration member 10 excites stretching vibration and bending vibration. 2A and 2B are views of the vibrating member 10 viewed in the stacking direction of the piezoelectric elements. FIG. 2A shows the shape of bending vibration, and FIG. 2B shows the shape of stretching vibration. The central portion of the vibration member 10 is a vibration node for both stretching vibration and bending vibration, and the hole 20 and the support member 40 are provided at this position. Further, a protrusion 30 is provided at the position of the antinode of bending vibration. By simultaneously exciting the expansion and contraction vibration and the bending vibration, the protrusion 30 performs an elliptical motion consisting of a displacement in the longitudinal direction of the vibration member 10 and a displacement in the width direction orthogonal thereto, and drives the moving body 60. Note that the two vibration modes are not limited in their orders, and other modes may be used.

  Next, the specific structure, polarization direction, and electrode arrangement of the vibration member 10 will be described. The vibration member 10 is formed by stacking five types of piezoelectric elements 11a, 11b, 12a, 12b, and 13 in the thickness direction. The piezoelectric element 11a is polarized in the thickness direction throughout. When the vibrating member 10 is formed by laminating, the piezoelectric element 11a is provided with the electrode 81 and the electrode 83 on the front and back. Therefore, by applying a drive signal between the electrode 81 and the electrode 83, stretching vibration is excited in a direction orthogonal to the thickness. In addition, the piezoelectric element 12a is polarized in the thickness direction in approximately four regions formed by connecting the centers of the length and width. In addition, as indicated by + or − in the figure, there are two types of polarization directions in one piezoelectric element. When the vibration member 10 is formed by stacking, the electrodes 82a, 82b, 82c, 82d and the electrode 84 are provided on the front and back of the piezoelectric element 12a. Therefore, when a drive signal is applied between the electrodes 82a, 82b, 82c, 82d and the electrode 84, bending vibration is excited in a direction orthogonal to the thickness direction of the piezoelectric element 12a. In addition, the hole 20 is provided in the center of the piezoelectric elements 12a and 12b, and the electrodes 82a, 82b, 82c, 82d, and 84 are provided so as to avoid the hole 20. In addition, a hole 20 is provided in the center of the piezoelectric elements 12 a, 12 b, and 13, and a support member 40 is connected to the hole 20. The piezoelectric element 13 is provided with external electrodes 881, 882 a, 882 b, 882 c, 882 d, 883, and 884, which extend to the side surface of the vibration member 10. Therefore, the external electrode 881 is the electrode 81, the external electrode 882a is the electrode 82, the external electrode 882b is the electrode 82b, the external electrode 882c is the electrode 82c, the external electrode 882d is the electrode 82d, the external electrode 883 is the electrode 83, The external electrodes 884 are electrically connected to the electrodes 84, respectively.

  Next, a method for driving the ultrasonic motor 1000 will be described. When a signal having a predetermined frequency is applied between the external electrodes 881 and 883, the piezoelectric element 11a constituting the vibration member 10 undergoes stretching vibration, and the external electrode 882a, 882b, 882c, 882d and 884 have a predetermined frequency. When a signal is applied, bending vibration is generated in the piezoelectric element 12a. Therefore, by changing the phase of the drive signal applied between the external electrodes 881 and 883 and the drive signal applied between the external electrodes 882a, 882b, 882c, 882d and 884, the protrusion 30 provided on the vibration member 10 is changed. The ellipse moves in a direction orthogonal to the thickness direction of the vibration member 10. Then, due to this elliptical motion, the moving body 60 in pressure contact with the protrusion 30 moves. By reversing the phase difference between the two signals, the direction of the elliptical motion is also reversed, so that the moving body can control the moving direction in two forward and reverse directions. In addition, since the support member 40 can be connected to the hole 20 by bonding, driving, fitting, joining, or the like for connection to the support member 40 that supports the vibration member 10, the vibration member 10 and the support member 40 can be connected to each other. Can be integrated with strength. In addition, a metal having high rigidity can be used for the support member 40, and the diameter of the hole 20 can be reduced. Therefore, a region for supporting the support member 10 can be reduced, and the vibration of the vibration member 10 can be used without weakening. Furthermore, since the hole 20 is provided in the vibration node of the vibration member 10, the vibration member 10 can be used without weakening the vibration, and thus the ultrasonic motor 1000 with high efficiency and high output can be realized.

(Embodiment 2)
FIG. 4 shows the vibration member 210 of the ultrasonic motor of the present invention. FIG. 4A is a perspective view of the vibration member 210, and FIG. 4B is a view for explaining a specific structure, polarization direction, and electrode arrangement of the vibration member 210. FIG. Only differences from the first embodiment will be described below.

  As in the first embodiment, the vibration member 210 shown in FIG. 4 has a plurality of piezoelectric elements 11a, 11b, 212a, 212b, and 213 stacked in the thickness direction. The difference from the first embodiment is that the piezoelectric elements 212a and 212b correspond to the piezoelectric elements 12a and 12b, the piezoelectric element 213 corresponds to the piezoelectric element 13, and the electrode 284 corresponding to the electrode 84 is provided without avoiding the hole 20. In the point. Thereby, the electrode 284 and the support member 40 are electrically connected by connecting the support member 40 to the hole 20 with a conductive adhesive or the like. Therefore, it is possible to apply a drive signal to the electrode 284 using the support member 40 without providing an external electrode. Note that adhesion using a conductive adhesive is an example of a connection method of the support member 40, and if the support member 40 can be electrically connected to the electrode 284, it can be implemented in the same manner by using means such as driving, fitting, and joining. It is. As a result, the number of signal applying means (not shown) such as lead wires connected to the external electrode can be reduced, so that the drive signal can be applied to the electrode 284 without hindering the vibration of the vibrating member 210. It is possible to use electric energy with high efficiency.

  FIG. 5 shows a vibration member 310 of the ultrasonic motor of the present invention. Similarly, only differences from the first embodiment will be described below.

  In the vibrating member 310 shown in FIG. 5, a plurality of piezoelectric elements 11a, 11b, 312a, 312b, and 313 are stacked in the thickness direction as in the first embodiment. The difference from the first embodiment is that the piezoelectric elements 312a and 312b correspond to the piezoelectric elements 12a and 12b, the piezoelectric element 313 corresponds to the piezoelectric element 13, and the electrodes 382a, 382b, 382c, and 382d correspond to the electrodes 82a, 82b, and 82c, respectively. 82d, and the electrodes 382a and 382c are provided without avoiding the hole 20. As a result, the electrodes 382a and 382c are electrically connected to the support member 40 by connecting the support member 40 to the hole 20 in the same manner as the vibration member 210 described above. Therefore, it is possible to apply a drive signal to the electrodes 382a and 382c using the support member 40 without providing an external electrode. As a result, a drive signal can be applied to the electrode without impeding the vibration of the vibration member 310 by a signal applying means (not shown) such as a lead wire connected to the external electrode, and high-efficiency electric Energy can be used.

(Embodiment 3)
FIG. 7 shows the vibration member 410 of the ultrasonic motor of the present invention. FIG. 7A is a perspective view of the vibration member 410, and FIG. 7B is a diagram illustrating a specific structure, polarization direction, and electrode arrangement of the vibration member 410. Differences from Embodiment 1 or 2 are mainly described below.

  As in the first and second embodiments, the vibration member 410 illustrated in FIG. 7 includes a plurality of piezoelectric elements 411a, 411b, 412a, and 413 stacked in the thickness direction. Differences from the first and second embodiments will be described below. First, the hole 20 is a through hole, and the support member 40 is one. The piezoelectric element 411a corresponds to the piezoelectric element 11a, the piezoelectric element 412a corresponds to the piezoelectric element 12a, the piezoelectric element 413 corresponds to the piezoelectric element 13, and the piezoelectric element 411b corresponds to the piezoelectric elements 11b and 12b. Thereby, since the electrode 483 corresponds to the electrode 83 and the electrode 84, it becomes the GND electrode of all the piezoelectric elements. The electrode 483 is provided without avoiding the hole 20. Thereby, as in the second embodiment, the electrode 483 and the support member 40 are electrically connected by connecting the support member 40 to the hole 20. Therefore, it is possible to apply a drive signal to the electrode 483 using the support member 40 without providing an external electrode. Further, when the vibration member 410 is configured, the electrode 81 is formed on the surface of the piezoelectric element 411a, the electrode 483 is formed on the back surface, the electrodes 82a, 82b, 82c, and 82d are formed on the surface of the piezoelectric element 412a, and the electrode 483 is formed on the back surface. Is provided. According to such a configuration, the piezoelectric elements 411a and 412a have the common electrode 483, and by grounding the electrode 483, one type of electrode group can be reduced, and manufacturing becomes easier.

  In addition, by using the hole 20 as a through hole, the piezoelectric elements 411a, 411b, 412a, and 413 have the same shape except for the electrodes, so that the manufacture becomes easy. Furthermore, it becomes a structure supported by one support member 40 by setting it as a through-hole. With such a configuration, the number of components can be reduced and the structure can be simplified, so that the configuration can be easily downsized.

  In FIG. 7, the pair of piezoelectric elements 412a and 411b are stacked so as to sandwich the pair of piezoelectric elements 411a and 411b. Then, two pairs of piezoelectric elements 411a and 411b and a pair of piezoelectric elements 412a and 411b are arranged symmetrically in the front and back direction when viewed from the center in the thickness direction of the vibration member 410. However, the ultrasonic motor can function even if these two pairs of piezoelectric elements are arranged alternately.

(Embodiment 4)
An example in which an electronic apparatus is configured using the ultrasonic motor of the present invention is shown in FIG.

  FIG. 6 shows a block diagram in which an ultrasonic motor 1000 driven by the drive circuit of the present invention is applied to a drive source of an electronic device. A movable mechanism 90 that operates integrally with a moving body 60 that is frictionally driven by a protrusion 30 provided on the vibration member 10, a drive control device 103 that applies a drive signal to the vibration member, and a measurement device that measures the amount of movement of the movable mechanism 90. 102. Here, an example of an automatic stage that uses the movable mechanism 90 as a stage and positions it at a predetermined position will be described.

  Here, the measuring apparatus 102 uses, for example, an optical encoder. The drive control device 103 recognizes the current position of the movable mechanism 90 from the measuring device 102 and moves the movable mechanism 90 in the direction of the target position. If the current position and the target position from the measuring device 102 coincide with each other within a predetermined range, the drive signal input is stopped.

  Note that the electronic apparatus in this embodiment can be applied to a printer, a machine tool, or the like in addition to an automatic stage.

  If the movable body of the ultrasonic motor of the present invention is directly provided with a movable stage or the operation of the movable body is transmitted via a transmission mechanism, an automatic stage, a zoom mechanism of a camera, an autofocus mechanism, a paper feeding device, or It can be applied to electronic devices such as watches.

It is a figure which shows the structure of the ultrasonic motor 1000 of this invention. It is explanatory drawing which shows the vibration mode of the vibration member 10 of the ultrasonic motor of this invention. It is a figure which shows the structure of the vibration member 10 of the ultrasonic motor of this invention. It is a figure which shows the structure of the vibration member 210 of the ultrasonic motor of this invention. It is a figure which shows the structure of the vibration member 310 of the ultrasonic motor of this invention. It is a figure which shows the electronic device using the ultrasonic motor of this invention. It is a figure which shows the structure of the vibration member 410 of the ultrasonic motor of this invention. It is a figure which shows the structure of the conventional ultrasonic motor.

Explanation of symbols

1000 ... ultrasonic motors 10, 210, 310, 410 ... vibration members 11a, 411a ... piezoelectric elements (stretching vibration)
12a, 212a, 312a, 412a ... Piezoelectric element (flexural vibration)
11b, 12b, 13, 212b, 213, 312b, 313 ... piezoelectric elements 411b, 413, 710 ... piezoelectric elements 20 ... holes 30, 730 ... protrusions 40,740 ... support members 50. ..Guide member 60 ... moving body 70 ... pressure member 81 ... electrode (stretching vibration)
82a, 82b, 82c, 82d, 382a, 382b, 382c, 382d ... Electrode (flexural vibration)
83, 84, 284, 483 ... electrode 90 ... movable mechanism 102 ... measuring device 103 ... drive control device 881 ... external electrode (stretching vibration)
882a, 882b, 882c, 882d ... External electrode (flexural vibration)
883, 884 ... External electrode 711 ... Vibrating body

Claims (5)

An ultrasonic motor comprising: a vibration member configured by stacking a first piezoelectric element group and a second piezoelectric element group; and a movable body that is in contact with the vibration member and is movable in accordance with vibration of the vibration member. ,
A hole provided in the first piezoelectric element group;
An ultrasonic motor comprising: a support member connected to the hole.   The ultrasonic motor according to claim 1, wherein the first piezoelectric element group excites bending vibration.   The ultrasonic motor according to claim 1, wherein at least a part of an electrode group provided in the first piezoelectric element group is disposed so as to avoid the hole. In an ultrasonic motor including a vibration member configured by laminating a plurality of piezoelectric elements, and a movable body that is in contact with the vibration member and is movable in accordance with vibration of the vibration member,
A hole provided in the piezoelectric element;
An ultrasonic motor comprising: a support member connected to the hole and electrically connected to a part of an electrode group provided in the piezoelectric element.   An electronic apparatus with an ultrasonic motor, comprising the ultrasonic motor according to any one of claims 1 to 4.

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