JPH05168263A - Supersonic vibrator - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic vibrator which is compact and has a large output without any damage during drive by providing a rod-shaped elastic body and a plurality of vibration-application means for applying vibration to a plurality of nodes at the resonance flex vibration at an ultrasonic vibrator and then shifting a plurality of vibration-application means in the vibration-application direction for other adjacent vibration-application means. CONSTITUTION:A bottom surface 11a and a side surface 11b of a base member 11 whose section is in L shape are formed at 90 degrees each other, lamination-type piezoelectric elements 12a and 12b are fixed in mutually vertical directions, and then retention members 14a and 14b for retaining a node at resonance flex vibration of an elastic body 13 are provided at each tip part, where a drive frequency voltage with a same frequency as a resonance frequency of the elastic body 13 is applied to the lamination-type piezoelectric element 12a and a resonance flex vibration with an amplitude in z-axis direction is generated at the elastic body 13. Furthermore, when a drive frequency voltage with a same frequency and with its phase being shifted by 90 degrees is applied to the lamination-type piezoelectric element 12b, the other node is vibrated in y-axis direction and a film of resonance flex vibration in the elastic body 13 performs rotary motion on y-z plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator, and more particularly to a vibrator using an electro-mechanical energy conversion element such as a piezoelectric element or an electrostrictive element.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a device in which an electro-mechanical energy conversion element such as a piezoelectric element or an electrostrictive element is used to excite vibration in an elastic body and the vibration is used as a drive source for an actuator. This has an advantage over a conventional drive source such as an electromagnetic motor in that the torque is high, the positioning accuracy is high, and no electromagnetic influence is given or received.

Such a driving system is disclosed in, for example, Japanese Patent Laid-Open No. 64
This is a technique known in JP-A-16272 and JP-A-63-110968. In Japanese Unexamined Patent Publication No. 64-16272, a laminated piezoelectric unit having an angle of 90 ° is fixed to a member pressed against a driven body, and these two piezoelectric units are alternately expanded and contracted to be driven. A piezoelectric motor configured to drive a body is described. Further, in Japanese Patent Application Laid-Open No. 63-110968, a piezoelectric element is attached to the side surface of a prismatic elastic body to form a drive body, and a plurality of bending vibrations are applied to the drive body by applying a voltage to the piezoelectric body. An ultrasonic linear motor that is excited and presses a driven member against this driving body is described.

[0004]

However, various problems occur in the above-mentioned conventional techniques. That is, in the piezoelectric motor disclosed in Japanese Patent Laid-Open No. 64-16272, the opposing piezoelectric units are provided in the same plane, so that the force generated by the vibration of one piezoelectric unit is mediated by the connecting portion of the two. As a result, the bending force is transmitted to the other piezoelectric unit side, and the piezoelectric unit is more likely to be broken. Furthermore, when a drive frequency voltage having a resonance frequency is applied to both piezoelectric units so that the piezoelectric units are in the optimum drive state, the bending force may be further increased.

Further, in the ultrasonic linear motor described in Japanese Patent Laid-Open No. 63-110968, two bending vibrations are excited to combine these bending vibrations, and the end face is rotationally vibrated. It is necessary to surely match the frequencies of the two bending vibrations with the resonance frequency of the elastic body. Further, when the shape of the elastic body is made small, it is difficult to obtain a large output because the area where the piezoelectric body is attached is reduced.

[0006]

SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to obtain a small-sized and high-power ultrasonic transducer which is not damaged during driving.

[0007]

In order to solve the above-mentioned problems, the present invention comprises a rod-shaped elastic body and a plurality of vibrating means for applying vibration to a plurality of nodes in resonance bending vibration of this elastic body. It is provided in an ultrasonic vibrator, and the vibrating directions of the plurality of vibrating means are shifted with respect to other vibrating means adjacent to each other.

[0008]

The ultrasonic transducer 1 according to the present invention will be described with reference to the conceptual diagram shown in FIG. Resonant bending vibration is generated in the rod-shaped elastic body 2 as shown in FIG. When the resonance bending vibration is schematically viewed, as shown in FIG.
a and 2b. The positions of these nodes 2a and 2b on the elastic body 1 can be specified in advance by the mechanical elements of the elastic body 2.

When vibration is applied to the nodes 2a and 2b at the same frequency as the resonance frequency of the elastic body 2 in the z-axis direction, resonance bending vibration having an amplitude in the z-axis direction is generated as shown in FIG. 1 (b). When the vibration is generated in the y-axis direction at the same frequency as the resonance frequency of the elastic body 2, resonance bending vibration having an amplitude in the y-axis direction is generated as shown in FIG.

Here, when a resonance frequency vibration in the z-axis direction is applied to the joint 2a and a resonance frequency vibration in the y-axis direction is applied to the joint 2b, the elastic body 2 causes the antinode 2c of the resonance bending vibration, as shown in FIG. 1 (d). Two
Each of d and 2e causes a rotational movement in the yz plane.

Here, for example, by pressing a movable member that is movable with respect to the elastic body 2 against the belly 2c, the belly 2
The rotational vibration force of c is applied to the movable member, and the movable member is moved with respect to the elastic body 2 in the y direction or the z direction in FIG.

【Example】

The present invention will be described in detail below with reference to the illustrated embodiments.

A first embodiment of the present invention will be described with reference to FIG.

FIG. 2 shows an ultrasonic transducer 10 according to this embodiment.
FIG. The bottom surface 11a and the side surface 11b of the base member 11 having an L-shaped cross section are formed at an angle of 90 ° with each other. And this bottom surface 11a and side surface 11b
The laminated piezoelectric elements 12a and 12b, which are laminated in a direction perpendicular to the bottom surface 11a and the side surface 11b, respectively, are fixed to the. Furthermore, these laminated piezoelectric elements 12a, 12
Holding members 14a and 14b for holding the nodes in the resonant bending vibration of the elastic body 13 are provided at the tip of b. The holding members 14a and 14b are made of the elastic body 13
To the base member 11 and the laminated piezoelectric elements 12a and 12b.
It is fixed so that it cannot rotate.

The elastic body 13 is formed of a round bar made of metal such as stainless steel, bearing steel, phosphor bronze, etc. The position of occurrence of a node in the resonance bending vibration of the elastic body 13 is previously calculated. Be done. In the case of so-called first-order mode resonant bending vibration in which two ends are free ends and two nodes are generated as in the present embodiment, when the total length of the elastic body 13 is L, 2
Each of the two nodes is 0.224L from the end face of the elastic body 13.
And at a position of 0.776L. Therefore, the distance between the laminated piezoelectric elements 12a and 12b in the length direction of the elastic body 13 is also determined in advance.

When the elastic body 13 is vibrated by the resonant bending vibration of the secondary mode in which three nodes are generated, the node is 0.1
When the vibration is generated at the positions of 32L, 0.5L, and 0.868L, respectively, and when vibrating by the resonant bending vibration of the third mode in which three nodes are generated, the nodes are 0.094L, 0.35.
It occurs at the positions of L, 0.644L and 0.906L, respectively. Therefore, a laminated piezoelectric element as a vibrating means may be provided at each position.

Next, the operation of this embodiment will be described. A drive frequency voltage having the same frequency as the resonance frequency of the elastic body 13 is applied to the laminated piezoelectric element 12a. As a result, the laminated piezoelectric element 12a expands and contracts at the bending resonance frequency of the elastic body 13,
One node is vibrated in the z-axis direction in FIG. Therefore, resonant bending vibration having an amplitude in the z-axis direction in FIG. 2 is generated in the elastic body 13.

Further, a drive frequency voltage having the same frequency as the drive frequency voltage of the stack type piezoelectric element 12a and a phase difference of 90 ° is applied to the stack type piezoelectric element 12b. As a result, the laminated piezoelectric element 12b expands and contracts in the y-axis direction in FIG. 2 and vibrates the other node in the y-axis direction in FIG. When only the expansion and contraction of the laminated piezoelectric element 12b is applied to the elastic body 13, resonance bending vibration having an amplitude in the y-axis direction in FIG. 2 is generated in the elastic body 13. However, in this embodiment, the resonance bending vibrations generated by the expansion and contraction of the laminated piezoelectric elements 12a and 12b are combined, and the antinodes of the resonance bending vibrations in the elastic body 13 make a rotational movement in the yz plane. To do. By switching the positive / negative phase difference of the voltage applied to the laminated piezoelectric element 12b with respect to the applied voltage to the laminated piezoelectric element 12a, the rotation direction in the yz plane is reversed.

With the above-mentioned structure, in this embodiment, a high-power ultrasonic transducer can be obtained with a simple structure. Further, since the driving frequency of the laminated piezoelectric elements 12a and 12b is a bending resonance frequency which is lower than the resonant frequency of the laminated piezoelectric elements 12a and 12b, the laminated piezoelectric elements 12a and 12b are driven. It is possible to minimize the load applied to.

A modification of this embodiment will be described with reference to the perspective view shown in FIG.

Disc-shaped load masses 15a, 15b, 15c are fixedly provided at the portions corresponding to the three antinodes of the first-order mode resonant bending vibration generated in the elastic body 13, respectively. By providing these load mass bodies 15a, 15b, 15c, the bending resonance frequency of the elastic body 13 is lowered. As a result, the mechanical Q is increased, and the efficiency when used in the resonance bending state is improved.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 shows an ultrasonic transducer 20 according to this embodiment.
It is a perspective view explaining. Base member 2 with L-shaped cross section
The bottom surface 21a and the side surface 21b of 1 are formed at an angle of 90 ° to each other. The bottom surface 21a and the side surface 21b are stacked on the bottom surface 21a and the side surface 21b in a direction perpendicular to the bottom surface 21a and the side surface 21b, respectively.
2b, 22c and 22d are fixed. Further, at the tips of the laminated piezoelectric elements 22a, 22b, 22c and 22d, holding members 24a, 24b, 24c and 24d respectively holding four nodes in the resonance bending vibration of the third mode generated in the elastic body 23 are respectively provided. Is provided. These holding members 24a, 24b, 24c, and 24d include the elastic body 23, the base member 21, and the laminated piezoelectric element 22a,
It is fixed so as not to rotate with respect to 22b, 22c and 22d. The load masses 25a, 25b, 2 are formed on the five antinodes in the resonance bending vibration of the third mode.
5c, 25d and 25e are fixed respectively.

The operation of this embodiment will be described. The laminated piezoelectric elements 22a and 22c and the laminated piezoelectric elements 22b and 22d are respectively used as one set of vibrating means, and the laminated piezoelectric elements 22a and 22a are
A drive frequency voltage having the same frequency as the resonance frequency of the elastic body 23 is applied to each of 22c. As a result, the laminated piezoelectric elements 22b and 22d expand and contract in the z-axis direction in FIG. 4 in the same phase, causing the nodes 23a and 23c to vibrate in the z-axis direction in FIG. Therefore, resonant bending vibration having an amplitude in the z-axis direction in FIG. 4 is generated in the elastic body 23.

Further, in the laminated piezoelectric elements 22b and 22d,
A drive frequency voltage having the same frequency as the drive frequency voltages of the laminated piezoelectric elements 22a and 22c and having a phase difference of 90 ° is applied. As a result, the laminated piezoelectric elements 22a and 22c expand and contract in the y-axis direction in FIG. 4, causing the nodes 23b and 23d to vibrate in the y-axis direction in FIG. When only the expansion and contraction of each of the laminated piezoelectric elements 23b and 23d is applied to the elastic body 23, resonance bending vibration having an amplitude in the y-axis direction in FIG. 4 is generated in the elastic body 23. However, in this embodiment, the resonance bending vibrations generated by the expansion and contraction of the laminated piezoelectric elements 22a, 22c and 22b, 22d are combined, and the elastic body 2
The five antinodes of the resonant bending vibration in 3 make rotational motion in the yz plane. As a result, the load mass bodies 25a, 2
5b, 25c, 25d and 25e each perform a rotational movement in the yz plane.

With the above-described structure, the ultrasonic vibrator 20 of this embodiment is provided with twice as many laminated piezoelectric elements as the vibrating means as compared with the ultrasonic vibrator 10 of the first embodiment described above. Therefore, the drive output increases.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 5A is a perspective view showing the ultrasonic transducer 30 in this embodiment. A bottom surface 31a and a side surface 31b of a base member 31 having an L-shaped cross section, which is formed of aluminum, stainless steel, brass or the like, are formed at an angle of 90 ° to each other. The bottom surface 31a and the side surface 31b are stacked on the bottom surface 31a and the side surface 31b, respectively.
32b is fixed.

Further, these laminated piezoelectric elements 32a, 32b
At the tip of each of the plate-like elastic arms 31c, 31 extending from the side surface 31b and the bottom surface 31a of the base member 31, respectively.
Holding members 31e and 31f, which are formed integrally with each other in d, respectively hold two nodes of the elastic body 33, which are generated by the resonant bending vibration of the primary mode. The holding members 31e and 31f fix the elastic body 33 to the base member 31 and the laminated piezoelectric elements 32a and 32b so as not to rotate. Further, the elastic body 33 has load mass bodies 33a, 33 at the antinode portion of the resonance bending vibration.
b and 33c are fixed.

Through holes 31g and 31h, into which the elastic body 33 is inserted, are formed in the holding members 31e and 31f, respectively, as shown in the partial sectional view of FIG. 5B. The inner peripheral surfaces of the through holes 31g and 31h are chamfered as shown in FIG. 5B, and the through hole 31 is formed at the center of the chamfered portion.
screw holes 31i and 31j in a direction perpendicular to g and 31h
Has been drilled. In these screw holes 31i and 31j,
After the elastic body 33 is inserted into the through holes 31g and 31h, the screws 34a and 34b are screwed into the through holes 31g and 31h to support the elastic body 33.

Next, the operation of this embodiment will be described. A drive frequency voltage having the same frequency as the resonance frequency of the elastic body 33 is applied to the laminated piezoelectric element 32a. As a result, the laminated piezoelectric element 32a expands and contracts at the resonance frequency of the elastic body 33, and
The portion 3a is vibrated in the z-axis direction in FIG. Therefore, resonant bending vibration having an amplitude in the z-axis direction in FIG. 5A is generated in the elastic body 33. At this time, the elastic arm 31c
Can vibrate in the z direction, but does not vibrate in the x and y directions, and restricts movement of the holding member 31e in the x and y directions.

Further, a driving frequency voltage having the same frequency as the driving frequency voltage of the laminated piezoelectric element 32a and a phase difference of 90 ° is applied to the laminated piezoelectric element 32b. As a result, the laminated piezoelectric element 32b expands and contracts in the y-axis direction in FIG. 5 (a), causing the node 33b to vibrate in the y-axis direction in FIG. 5 (a).
At this time, the elastic arm 31d can vibrate in the y direction but does not vibrate in the x and z directions, and restricts the holding member 31f from moving in the x and z directions. When only the expansion and contraction of the laminated piezoelectric element 32b is applied to the node 33b of the elastic body 33, the elastic body 3
Resonant bending vibration having an amplitude in the y-axis direction in FIG. However, in the present embodiment, the resonance bending vibrations generated by the expansion and contraction of the laminated piezoelectric elements 32a and 32b are combined, and the antinodes of the resonance bending vibrations in the elastic body 33 cause rotational movement in the yz plane. To do.

With the above-described structure, in this embodiment, by providing the elastic arms 31c and 31d, the rigidity of the holding members 31e and 31f is improved, and the laminated piezoelectric elements 32a and 32b receive a force other than the expansion / contraction direction. It will not be added, and the laminated piezoelectric elements 32a and 32b will not be destroyed during driving. Also, the holding members 31e, 31
Since the contact area between f and the elastic body 33 is reduced, it is possible to obtain a highly efficient ultrasonic transducer without inhibiting resonance bending vibration of the elastic body 33.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 6 shows an ultrasonic transducer 40 according to this embodiment.
It is a perspective view showing. Multilayer piezoelectric elements 41 and 42, which are laminated in the x-axis direction and the z-axis direction, are arranged at a predetermined interval in the y-axis direction. At both ends of the laminated piezoelectric element 41 in the laminating direction, elastic arms extending in a direction perpendicular to the laminating direction of the laminated piezoelectric element 41, that is, a z-axis direction, from first fixing portions 43 fixed to a base member (not shown). 43
holding members 43c and 43d formed integrally with a and 43b
Is fixed. Further, both ends of the laminated piezoelectric element 42 in the laminating direction extend in a direction perpendicular to the laminating direction of the laminated piezoelectric element 42, that is, in the x-axis direction from second fixing portions 44 fixed to a base member (not shown). Elastic arms 44a, 44b
The holding members 44c and 44d formed integrally with the are fixed.

The elastic members 4 are attached to the holding members 43c and 43d.
Through holes for holding one of the two nodes, which are generated by the resonant bending vibration of the first-order mode of Nos. 5 and 46, respectively, are provided. Similar to the holding members 31e and 31f in the third embodiment described above, these through holes have chamfered inner peripheral surfaces (not shown), and the center of the chamfered portion has a direction perpendicular to the through holes. A screw hole (not shown) is formed in the. By screwing a screw (not shown) into this screw hole, one of the nodes of the elastic bodies 45 and 46 is held by the holding members 43c and 43d, respectively.

The holding members 44c and 44d have the same structure as the holding members 43c and 43d, and the elastic member 4
Of the two nodes generated by the resonant bending vibrations of the first-order modes 5 and 46, the other node is retained. Further, the load mass bodies 45a, 45 are formed on the antinodes of the elastic bodies 45, 46 generated by the first-order mode resonant bending vibration.
b, 45c and 46a, 46b, 46c are fixed. The elastic bodies 45 and 46 are
They are arranged in a twisted relationship.

The operation of this embodiment will be described. A driving frequency voltage having the same frequency as the bending resonance frequency of the elastic bodies 45 and 46 is applied to the laminated piezoelectric elements 41 and 42, respectively. The phase of the drive frequency voltage applied to the laminated piezoelectric element 42 is shifted by 90 ° with respect to the phase of the drive frequency voltage applied to the laminated piezoelectric element 41. Resonant bending vibrations that rotate the antinodes are generated in the elastic bodies 45 and 46 as in the above-described embodiment.

At this time, the driven members, which are movable with respect to the ultrasonic transducer 40, are pressed against the load mass bodies 45b and 46b, so that the driven members are elastic bodies 45 and 46.
Is driven in the direction in which the rotational bending vibrations of are combined.

With the configuration as described above, in the ultrasonic transducer 40 of this embodiment, the two laminated piezoelectric elements 4 are
Since the two elastic bodies 45 and 46 are resonantly flexurally vibrated by the motors 1 and 42, a high driving force can be obtained with a smaller applied voltage than the above-described embodiment.

An example in which the ultrasonic transducer according to the present invention is used as a drive source for a linear ultrasonic motor will be described as a fifth embodiment with reference to FIG.

FIG. 7 is a perspective view for explaining the linear ultrasonic motor 50 in this embodiment. In addition, in this embodiment, the ultrasonic transducer 30 in the above-described third embodiment is used as a drive source in the linear ultrasonic motor 50,
The same reference numerals are given to those having no structural difference from the third embodiment, and detailed description thereof will be omitted.

The base material 51 includes an inverted U-shaped bridge portion 51.
a is formed, and the ultrasonic transducer 30 is arranged at the upper end of the bridge portion 51a such that the elastic body 33 is located downward and the elastic body 33 is extended in the x direction. A spring 51c is provided on the bottom surface 51b of the base material 51. The spring 51c includes a guide rail 53 supported by a fixing member (not shown) and a pressing roller 52 supported by a connecting arm 52.
a, 52b and the load mass body 33b of the elastic body 33 so as to be sandwiched therebetween, the connecting arm 52 and the pressing rollers 52a, 52
b is urged upward in the z-axis direction.

The load mass body 33b of the elastic body 33 is provided with a sliding member 54 at a portion in contact with the guide rail 53. The sliding member 54 is usually made of stainless steel, brass, polyimide film, PPS, carbon plate, ceramic plate, aluminum anodized plate, or the like. In this embodiment, as the sliding member 54, stainless steel processed into a desired shape is used. It goes without saying that the load mass body 33b itself may be formed of these materials.

The operation of this embodiment will be described. A driving frequency voltage having a phase difference of 90 ° is applied to the laminated piezoelectric elements 32a and 32b. The frequency of the drive frequency voltage is the elastic body 33.
The resonance bending frequency of As a result, the antinode of the resonance bending vibration of the elastic body 33 performs rotational vibration in the yz plane. Therefore, a driving force in the y-axis direction is applied to the guide rail 53, and the ultrasonic transducer 30 moves in the y-axis direction with respect to the guide rail 53. By changing the phase difference between the voltage applied to the laminated piezoelectric element 32b and the drive frequency voltage applied to the laminated piezoelectric element 32a, the rotation direction of the antinode in the resonance bending vibration of the elastic body 33 in the yz plane. Is reversed, the movement direction in the y-axis direction can be controlled.

According to the present embodiment, the linear ultrasonic motor 50 having a small size and a simple structure and a high driving force can be obtained by the above structure. In this embodiment, the driving force is applied to the guide rail 53 to move the ultrasonic transducer 30 itself, but instead of the guide rail 53, the rotation rotatably supported by the shaft at a predetermined position. Of course, the members may be configured to be driven to rotate.

In the above-described embodiments, the laminated piezoelectric element is used as the vibrating means of the ultrasonic vibrator, but this may be a laminate of a plurality of electrostrictive elements or magnetostrictive elements. Alternatively, a displacement magnifying mechanism for magnifying the vibration of these drive sources may be provided. Further, the vibration directions of the laminated piezoelectric elements are shifted by 90 ° between the adjacent ones, but this may be any number such as 120 ° and 60 ° as long as they are not located in the same plane. In this case, the phase difference between the drive frequency voltages of the adjacent laminated piezoelectric elements may be changed as appropriate.

[0048]

As described above in detail, in the ultrasonic vibrator of the present invention, vibration is applied to a plurality of nodes in the resonance bending vibration of the rod-shaped elastic body in the directions displaced by the adjacent nodes. Since it is configured, it is possible to obtain the one with high driving efficiency with a simple configuration.

[Brief description of drawings]

FIG. 1A to FIG. 1D are views for explaining the concept of the present invention.

FIG. 2 is a perspective view showing a first embodiment of the present invention.

FIG. 3 is a perspective view showing a modified example of the first embodiment.

FIG. 4 is a perspective view showing a second embodiment of the present invention.

5A is a perspective view showing a third embodiment of the present invention, FIG.
FIG. 6B is a partial sectional view of the third embodiment.

FIG. 6 is a perspective view showing a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a fifth embodiment in which the ultrasonic transducer according to the invention is used as a drive source for a linear ultrasonic motor.

[Explanation of symbols]

1, 10, 20, 30, 40 Ultrasonic transducer 2, 13, 23, 33, 47, 48 Elastic body 12a, 12b, 22a, 22b, 22c, 22d, 3
2a, 32b, 41, 42 Multilayer piezoelectric element (vibrating means)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoshihisa Taniguchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Toshiharu Tsubata 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Hiroyuki Imabayashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Katsuhiro Wakabayashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd.

Claims (3)

[Claims] 1. A rod-shaped elastic body, and a plurality of vibrating means for applying vibration to a plurality of nodes of resonance bending vibration of the elastic body, wherein the plurality of vibrating means are adjacent to each other. The ultrasonic transducer is characterized in that the vibration direction is deviated from the other vibration means. 2. A mass body serving as a load is provided at an antinode portion of the elastic flexural vibration of the elastic body,
The ultrasonic transducer according to claim 1. 3. The ultrasonic vibration according to claim 1, further comprising a movable member which is pressed against an antinode portion of the resonance bending vibration of the elastic body and is movable with respect to the elastic body. Child.