JP2012120370A - Ultrasonic transducer and ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic transducer capable of realizing a thin ultrasonic motor with multi-degree of freedom, and to provide an ultrasonic motor using the ultrasonic transducer.SOLUTION: An ultrasonic transducer 10 for driving a driver 20 to be driven in a plurality of driving directions comprises: an elastic body 10 including a frame body 10f, and branch parts 10-A, 10-B, 10-C, and 10-D for configuring a plurality of beam parts supported in a both-end support by the frame body 10f; drivers A1d, B1d, C1d, and D1d provided on a surface facing the driver 20 to be driven in the elastic bodies 10; a plurality of piezoelectric elements A1, B1, C1, and D1 provided on a surface facing to the driver 20 to be driven in the beam parts; and a plurality of piezoelectric elements A2, B2, C2, and D2 provided on the rear surface thereof. The plurality of beam parts of the elastic body 10 extend in respective directions corresponding to different driving directions, and intersect each other, and expansion and contraction vibration of the plurality of piezoelectric elements A1, B1, C1, D1, A2, B2, C2, and D2 excites elliptical vibration at a part related to the intersection in the elastic body 10.

Description

  The present invention relates to an ultrasonic vibrator and an ultrasonic motor using a vibrator such as a piezoelectric element.

  In recent years, ultrasonic motors using vibrations of vibrators such as piezoelectric elements have attracted attention as new motors that replace electromagnetic motors. Compared with conventional electromagnetic motors, this ultrasonic motor has low speed and high thrust without gears, high holding power, high resolution, quietness, and magnetic noise. It has the advantage that it does not occur.

  Specifically, an ultrasonic motor of a type that excites elliptical vibration by applying a predetermined alternating voltage to a vibrator and frictionally drives a driven member using the elliptical vibration as a driving source is known. As a technique relating to such an ultrasonic motor, for example, Patent Document 1 discloses the following technique.

  That is, the ultrasonic motor disclosed in Patent Document 1 includes a piezoelectric element having a plurality of electrode portions, a vibrating body, a rotating body (driven body) that rotates in contact with the vibrating body, and the vibrating body. And a pressure member (pressing mechanism) that applies pressure to the rotating body. And the bending direction of the bending vibration excited by the said vibrating body is determined by selecting at least one electrode part among the said several electrode parts, and applying a voltage. By adopting such a configuration, the ultrasonic motor disclosed in Patent Document 1 realizes driving in a plurality of directions with a single vibrator.

JP 2005-295657 A

  By the way, with the technique currently disclosed by patent document 1, the to-be-driven body (rotating body) and the press mechanism (pressing member) are arrange | positioned at the end surface side in the longitudinal direction of a vibrating body. For this reason, it becomes long (dimensions) in a direction perpendicular to the drive direction of the driven body. Therefore, it is very difficult to reduce the thickness of the ultrasonic motor.

In addition, it is very difficult to make the longitudinal direction of the vibrating body short because of the limitation of using flexural vibration for driving.
The present invention has been made in view of the above circumstances, and provides an ultrasonic vibrator that realizes thinning of a multi-degree-of-freedom ultrasonic motor, and an ultrasonic motor using the ultrasonic vibrator. For the purpose.

In order to achieve the above object, an ultrasonic transducer according to the first aspect of the present invention comprises:
An ultrasonic transducer for driving a driven body in a plurality of driving directions,
An elastic body comprising a frame and a plurality of beam portions supported by both sides of the frame;
A driver provided on a surface of the elastic body facing the driven body;
A plurality of piezoelectric portions provided on the opposite surface of the beam portion to the driven body and the back surface thereof,
Comprising
The plurality of beam portions of the elastic body extend in directions corresponding to driving directions different from each other and intersect each other,
In the elastic body, elliptical vibrations are excited by the stretching vibrations of the plurality of piezoelectric parts at the intersections.

In order to achieve the above object, an ultrasonic motor according to the second aspect of the present invention comprises:
A driven body arranged to be drivable in a plurality of directions;
An elastic body comprising a frame and a plurality of beam portions supported by both sides of the frame;
A driver provided on a surface of the elastic body facing the driven body and being in pressure contact with the driven body;
A plurality of piezoelectric portions provided on the opposite surface of the beam portion to the driven body and the back surface thereof,
Comprising
The plurality of beam portions of the elastic body extend in directions corresponding to driving directions different from each other and intersect each other,
Elliptical vibrations are excited by the stretching vibrations of the plurality of piezoelectric portions at the intersections of the elastic bodies.
The driven body is frictionally driven by the driver using the elliptical vibration as a driving source.

  ADVANTAGE OF THE INVENTION According to this invention, the ultrasonic vibrator which implement | achieves thickness reduction of a multi-degree-of-freedom ultrasonic motor, and the ultrasonic motor using this ultrasonic vibrator can be provided.

The figure which shows the example of 1 structure of the ultrasonic motor to which the ultrasonic transducer | vibrator which concerns on one Embodiment of this invention is applied. The top view of the ultrasonic motor shown in FIG. The bottom view of the ultrasonic motor shown in FIG. The side view of the ultrasonic motor shown in FIG. FIG. 3 is an arrow view of the NN cross section shown in FIG. 2. The perspective view which shows an example of the deformation | transformation state of the elastic body at the time of a X direction vibration mode. The arrow MM view of the MM cross section shown in FIG. The perspective view which shows an example of the deformation | transformation state of the elastic body at the time of Z direction vibration mode. The figure which shows an example of the drive signal applied to piezoelectric element A1, A2, B1, B2. The figure which shows an example of the drive signal applied to piezoelectric element C1, C2, D1, D2. The arrow MM view of the MM cross section shown in FIG. The perspective view which shows an example of the deformation | transformation state of the elastic body at the time of a Y direction vibration mode. FIG. 3 is an arrow view of the NN cross section shown in FIG. 2. The perspective view which shows an example of the deformation | transformation state of the elastic body at the time of Z direction vibration mode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of an ultrasonic motor to which an ultrasonic transducer according to an embodiment of the present invention is applied. FIG. 2 is a top view of the ultrasonic motor. FIG. 3 is a bottom view of the ultrasonic motor. FIG. 4 is a side view of the ultrasonic motor (a side view seen from the direction indicated by an arrow E1 in FIGS. 2 and 3).

The ultrasonic motor according to the present embodiment includes an elastic body 10, piezoelectric elements A1, A2, B1, B2, C1, C2, D1, and D2, drivers A1d, B1d, C1d, and D1d, and a driven body 20. And.
The elastic body 10 includes a frame body 10f and branch portions 10-A, 10-B, 10-C, and 10-D. Examples of the material of the elastic body 10 include brass and stainless steel.

The frame body 10f is a frame body having a square shape in plan view (see FIGS. 2 and 3) and having a hollow region in the vicinity of the center.
The said branch part 10-A, 10-B, 10-C, 10-D is a branch part connected so that a cross shape may be exhibited in the hollow area | region of the frame 10f.

The piezoelectric elements A1, B1, C1, and D1 are piezoelectric elements that are fixed to the upper surfaces of the branch portions 10-A, 10-B, 10-C, and 10-D, respectively, by bonding or the like (see FIG. 2). .
The piezoelectric elements A2, B2, C2, and D2 are piezoelectric elements that are fixed to the lower surfaces of the branch portions 10-A, 10-B, 10-C, and 10-D, respectively, by bonding or the like (see FIG. 3). .

  Here, the piezoelectric element A1 and the piezoelectric element A2 are disposed at positions corresponding to each other on the upper and lower surfaces of the branch portion 10-A. The piezoelectric element B1 and the piezoelectric element B2 are disposed at positions corresponding to each other on the upper and lower surfaces of the branch portion 10-B. The piezoelectric element C1 and the piezoelectric element C2 are disposed at positions corresponding to each other on the upper and lower surfaces of the branch portion 10-C. The piezoelectric element D1 and the piezoelectric element D2 are disposed at positions corresponding to each other on the upper and lower surfaces of the branch part 10-D.

  In other words, the piezoelectric elements A1, B1, C1, D1, A2, B2, C2, and D2 each include a beam portion that includes a branch portion 10-A and a branch portion 10-B and is supported at both ends by the frame body 10f. , The center point of the cross-related portion (cross-crossing portion CR) among the cross-members constituted by the beam portion that is composed of the branch portion 10-C and the branch portion 10-D and is supported by the frame 10f. Are arranged symmetrically with respect to the intersection), and the upper and lower surfaces of the elastic body 10 are arranged in the same manner.

  The driver A1d is a driver arranged in parallel with the piezoelectric element A1 in the vicinity of the cross intersection CR on the upper surface of the branch portion 10-A. The driver B1d is a driver arranged in parallel with the piezoelectric element B1 in the vicinity of the cross intersection CR on the upper surface of the branch portion 10-B. The driver C1d is a driver arranged in parallel with the piezoelectric element C1 in the vicinity of the cross intersection CR on the upper surface of the branch portion 10-C. The driver D1d is a driver arranged in parallel with the piezoelectric element D1 in the vicinity of the crossing portion CR on the upper surface of the branch portion 10-D.

These driver elements A1d, B1d, C1d, and D1d have one surface fixed to the branch portions 10-A, 10-B, 10-C, and 10-D by adhesion, for example, and the other surface is driven. Contact the body 20.
The ultrasonic transducer according to the present embodiment includes the elastic body 10 described above, piezoelectric elements A1, A2, B1, B2, C1, C2, D1, and D2, and driver elements A1d, B1d, C1d, and D1d. It is configured.

  By the way, in the ultrasonic transducer according to the present embodiment, three types of vibration modes (an “X direction vibration mode” in which the cross portion C vibrates in the X direction, a “Y direction vibration mode” in which the cross section C vibrates in the Y direction, and There are “Z-direction vibration modes” that vibrate in the Z direction, and the thickness of the elastic body 10 and the branch portions 10-A, 10-B, and 10-C are such that their natural frequencies have substantially the same value. , 10-D length and other dimensions are set.

Although details will be described later, each vibration mode is excited by expansion and contraction of each piezoelectric element, and elliptical vibration is excited in the vicinity of each driver by simultaneously exciting each vibration mode in combination.
The driven body 20 is disposed on the upper surface side of the elastic body 10 and is in contact with the driving elements A1d, B1d, C1d, D1d. The driven body 20 is frictionally driven by the driver elements A1d, B1d, C1d, and D1d. The driven body 20 and the driver elements A1d, B1d, C1d, and D1d are in a pressure contact state due to, for example, the weight of the driven body 20 or the like.

The driven body 20 is supported by a guide mechanism (not shown) so that it can be driven in the XY directions shown in FIGS. 1 to 3 (in the XY plane).
The above-described frame body 10f has fixing holes 10h1, 10h2, 10h3, and 10h4 at the four corners. Using these fixing holes 10h1, 10h2, 10h3, and 10h4, a pressing mechanism (not shown) (for example, a coil spring) is used to further increase the pressing force of the driving elements A1d, B1d, C1d, and D1d to the driven body 20. It is also possible to assemble a screw fastening mechanism.

Hereinafter, an example of a method for driving the ultrasonic motor according to the present embodiment will be described in detail. The driving method of the driven body 20 on the XY plane will be described in detail separately for driving in the X direction and driving in the Y direction.
《Drive in X direction》
FIG. 5 is an arrow view of the NN cross section shown in FIG. FIG. 6 is a perspective view showing an example of a deformed state of the elastic body in the X direction vibration mode. FIG. 7 is an arrow view of the MM cross section shown in FIG. FIG. 8 is a perspective view showing an example of a deformed state of the elastic body in the Z direction vibration mode. FIG. 9 is a diagram illustrating an example of drive signals applied to the piezoelectric elements A1, A2, B1, and B2. FIG. 10 is a diagram illustrating an example of drive signals applied to the piezoelectric elements C1, C2, D1, and D2. Here, in each of the piezoelectric elements A1, A2, B1, and B2, expansion deformation occurs when the voltage V applied as a drive signal is a positive value, and contraction deformation occurs when the voltage V is a negative value. .

Hereinafter, an example in which the driven body 20 is driven using the X-direction vibration mode shown in FIGS. 5 and 6 and the Z-direction vibration mode shown in FIGS. 7 and 8 will be described.
As shown in FIG. 9, the drive signal applied to the piezoelectric element A1 and the drive signal applied to the piezoelectric element A2 are set in phase, and the drive signal applied to the piezoelectric element B1 is applied to the piezoelectric element B2. Set the drive signal in phase. Further, the drive signals applied to the piezoelectric elements A1 and A2 and the drive signals applied to the piezoelectric elements B1 and B2 are set so as to have opposite phases as shown in FIG.

  By applying such a drive signal to the piezoelectric elements A1, A2, B1, and B2, the piezoelectric element A1 and the piezoelectric element A2 arranged in the X-axis direction as shown in FIG. 5 are simultaneously expanded and contracted, and The piezoelectric element B1 and the piezoelectric element B2 are simultaneously expanded and contracted in opposite phases to the piezoelectric elements A1 and A2. As a result, the elastic body 10 can be deformed in the direction indicated by the double arrow X in FIGS. 5 and 6.

In other words, by applying the drive signal described above to the piezoelectric elements A1, A2, B1, and B2, the elastic body 10 undergoes a deformation in which the cross-cross portion CR translates as shown in FIGS. Becomes the excitation force in the X direction, and the X direction vibration mode is excited.
On the other hand, as shown in FIGS. 9 and 10, a drive signal having the same phase as the drive signals applied to the piezoelectric elements A1 and A2 is applied to the piezoelectric element C1 and the piezoelectric element D1, and the piezoelectric element C2 and the piezoelectric element are applied. A drive signal having the same phase as the drive signal applied to the piezoelectric elements B1 and B2 is applied to D2.

  By applying such a drive signal to the piezoelectric elements C1, C2, D1, and D2, the piezoelectric element C1 and the piezoelectric element C2 expand and contract in opposite phases as shown in FIG. 7, and the piezoelectric element D1 and the piezoelectric element The element D2 can be expanded and contracted in opposite phases. Here, the piezoelectric element C1 and the piezoelectric element D1 are expanded and contracted in the same phase, and the piezoelectric element C2 and the piezoelectric element D2 are expanded and contracted in the same phase.

  As a result, the elastic body 10 can be deformed in the direction indicated by the double arrow Z in FIGS. Thereby, as shown in FIG.7 and FIG.8, the deformation | transformation which each branch part bends to a Z-axis direction arises, This deformation | transformation becomes an excitation force about a Z direction, and a Z direction vibration mode is excited.

  The phase difference between the X direction vibration mode shown in FIGS. 5 and 6 and the Z direction vibration mode shown in FIGS. 7 and 8 (the drive signal applied to the piezoelectric elements A1, A2, B1, and B2, and the piezoelectric element C1). , C2, D1, and D2), the elliptical vibration in the XZ plane is generated near the cross intersection CR, and the driven body 20 is driven in the X direction. It becomes possible.

Specifically, the phase difference between the drive signal applied to the piezoelectric elements A1, A2, B1, and B2 and the drive signal applied to the piezoelectric elements C1, C2, D1, and D2 is set to 90 degrees. Thereby, elliptical vibration in the XZ plane is generated in the vicinity of the cross intersection CR, and the driven body 20 can be frictionally driven in the X direction by the driver elements A1d, B1d, C1d, and D1d.
<< Driving in Y direction >>
11 is a cross-sectional view of the MM cross section shown in FIG. FIG. 12 is a perspective view illustrating an example of a deformed state of the elastic body in the Y-direction vibration mode. 13 is an arrow view of the NN cross section shown in FIG. FIG. 14 is a perspective view showing an example of a deformed state of the elastic body in the Z direction vibration mode.

As shown in FIG. 11, the piezoelectric element C1 and the piezoelectric element C2 are expanded and contracted in the same phase, and the piezoelectric element D1 and the piezoelectric element D2 are expanded and contracted in the same phase. In addition, the piezoelectric element C1 and the piezoelectric element C2, and the piezoelectric element D1 and the piezoelectric element D2 are set to expand and contract in opposite phases.
That is, the drive signal applied to the piezoelectric element C1 and the drive signal applied to the piezoelectric element C2 are set in phase, and the drive signal applied to the piezoelectric element D1 and drive signal applied to the piezoelectric element D2 are in phase. Set to. The drive signals applied to the piezoelectric elements C1 and C2 and the drive signals applied to the piezoelectric elements D1 and D2 are set so as to have opposite phases.

  By applying such a drive signal to the piezoelectric elements C1, C2, D1, and D2, the piezoelectric elements C1 and C2 are simultaneously expanded and contracted as shown in FIG. 11, and the piezoelectric elements D1 and D2 are expanded and contracted. The piezoelectric elements C1 and C2 are simultaneously expanded and contracted in the opposite phase. As a result, the elastic body 10 can be deformed in the direction indicated by the double arrow Y in FIGS. 11 and 12.

In other words, by applying the drive signal described above to the piezoelectric elements C1, C2, D1, and D2, the elastic body 10 undergoes a deformation in which the cross-cross portion CR translates as shown in FIGS. Becomes the excitation force in the Y direction, and the Y direction vibration mode is excited.
On the other hand, as shown in FIG. 13, the piezoelectric element A1 and the piezoelectric element A2 are expanded and contracted in opposite phases, and the piezoelectric element B1 and the piezoelectric element B2 are expanded and contracted in opposite phases. Further, the piezoelectric element A1 and the piezoelectric element B1 are set to be in phase, and the piezoelectric element A2 and the piezoelectric element B2 are set to be in phase.

  That is, the drive signal applied to the piezoelectric element A1 and the drive signal applied to the piezoelectric element B1 are set in phase, and the drive signal applied to the piezoelectric element A2 and drive signal applied to the piezoelectric element B2 are in phase. Set to. Here, the drive signals applied to the piezoelectric elements A1 and B1 and the drive signals applied to the piezoelectric elements A2 and B2 are set so as to have opposite phases.

  By applying such a drive signal to the piezoelectric elements A1, A2, B1, and B2, as a result, the elastic body 10 can be deformed in the direction indicated by the double arrow Z in FIGS. As a result, as shown in FIGS. 13 and 14, a deformation occurs in which each branch portion bends in the Z-axis direction, and the deformation becomes an excitation force in the Z direction, and the Z-direction vibration mode is excited.

In other words, by applying the drive signal to the piezoelectric elements A1, A2, B1, and B2, the elastic body 10 undergoes a deformation that translates the cross intersection CR as shown in FIG. 14, and the deformation occurs in the Z direction. The Z-direction vibration mode as shown in FIG. 14 is excited.
The phase difference between the Y-direction vibration mode shown in FIGS. 11 and 12 and the Z-direction vibration mode shown in FIGS. 13 and 14 (the drive signal applied to the piezoelectric elements A1, A2, B1, and B2, and the piezoelectric element C1). , C2, D1, and D2), the elliptical vibration in the YZ plane is generated in the vicinity of the cross intersection CR, and the driven body 20 is driven in the Y direction. It becomes possible.

  Specifically, the phase difference between the drive signal applied to the piezoelectric elements A1, A2, B1, and B2 and the drive signal applied to the piezoelectric elements C1, C2, D1, and D2 is set to 90 degrees. Thereby, elliptical vibration in the YZ plane is generated in the vicinity of the cross intersection CR, and the driven body 20 can be frictionally driven in the Y direction by the driver elements A1d, B1d, C1d, and D1d.

As described above, according to the present embodiment, it is possible to provide an ultrasonic vibrator that realizes thinning of a multi-degree-of-freedom ultrasonic motor, and an ultrasonic motor using the ultrasonic vibrator. .
That is, the driven body is selectively driven in the X direction and the Y direction by appropriately combining and expanding the eight piezoelectric elements A1, B1, C1, D1, A2, B2, C2, and D2 as described above. This has realized a multi-degree-of-freedom ultrasonic motor with a very simple configuration and reduced thickness.

  In other words, piezoelectric elements (A1, A2) are respectively formed on the front and back surfaces of an elastic body (elastic body 10) having cross-shaped portions (branches 10-A, 10-B, 10-C, 10-D). , B1, B2, C1, C2, D1, D2) are fixed, and elliptical vibration is generated at the cross-cross portion (cross-cross portion CR) in the cross shape by a combination of expansion and contraction of these piezoelectric elements. Then, the driven body (driven body 20) that is brought into pressure contact with the cross-crossing portion that vibrates elliptically is driven with two degrees of freedom. By adopting such a configuration, a thin and multi-degree-of-freedom ultrasonic motor is realized.

The present invention has been described based on one embodiment. However, the present invention is not limited to the above-described embodiment, and various modifications and applications are possible within the scope of the gist of the present invention. It is.
For example, the number of branch portions provided in the elastic body is not limited to four, and the shape of the branch portions may not be a cross shape. Further, the number of piezoelectric elements provided in the branch portion is not limited to eight, and may be appropriately provided according to the shape exhibited by the branch portion. Further, the driver element may be provided as appropriate according to the arrangement of the branch portions and the piezoelectric elements.

  Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention can be achieved. In the case of being obtained, a configuration from which this configuration requirement is deleted can also be extracted as an invention.

    A1d, B1d, C1d, D1d ... Driver, A1, A2, B1, B2, C1, C2, D1, D2 ... Piezoelectric element, CR ... Cross intersection, 10 ... Elastic body, 10f ... Frame, 10-A, 10-B, 10-C, 10-D ... branches, 10h1, 10h2, 10h3, 10h4 ... fixing hole, 20 ... driven body.

Claims (4)

An ultrasonic transducer for driving a driven body in a plurality of driving directions,
An elastic body comprising a frame and a plurality of beam portions supported by both sides of the frame;
A driver provided on a surface of the elastic body facing the driven body;
A plurality of piezoelectric portions provided on the opposite surface of the beam portion to the driven body and the back surface thereof,
Comprising
The plurality of beam portions of the elastic body extend in directions corresponding to driving directions different from each other and intersect each other,
The ultrasonic vibrator is characterized in that elliptical vibrations are excited by the stretching vibrations of the plurality of piezoelectric portions at the crossing portions of the elastic body. The piezoelectric parts are arranged point-symmetrically with respect to the intersection of the parts related to the intersection of the beam parts, and are arranged in the same arrangement manner on the facing surface and the back surface. The ultrasonic transducer according to claim 1. A driven body arranged to be drivable in a plurality of directions;
An elastic body comprising a frame and a plurality of beam portions supported by both sides of the frame;
A driver provided on a surface of the elastic body facing the driven body and being in pressure contact with the driven body;
A plurality of piezoelectric portions provided on the opposite surface of the beam portion to the driven body and the back surface thereof,
Comprising
The plurality of beam portions of the elastic body extend in directions corresponding to driving directions different from each other and intersect each other,
Elliptical vibrations are excited by the stretching vibrations of the plurality of piezoelectric portions at the intersections of the elastic bodies.
The ultrasonic motor is characterized in that the driven body is frictionally driven by the driver using the elliptical vibration as a driving source. The piezoelectric parts are arranged point-symmetrically with respect to the intersection of the parts related to the intersection of the beam parts, and are arranged in the same arrangement manner on the facing surface and the back surface. The ultrasonic motor according to claim 3.

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