JPH07255189A - Ultrasonic actuator - Google Patents

Abstract

PURPOSE:To provide a small-sized ultrasonic actuator which can get a large driving force. CONSTITUTION:This relates to an ultrasonic actuator being equipped with multilayer piezoelectric substances 11a and 11b, which generate ultrasonic oscillation, an elastic body 12, which generates elliptic oscillation, receiving the action of these multilayer piezoelectric substances 11a and 11b, and a driven body which parallels that elastic body 12 by the elliptic oscillation, being energized to this elastic body 12. This is an ultrasonic actuator in which the elastic bodies 12 are made symmetrical about a line, and the elliptic motions occur on both sides of the axis of symmetry, and the directions of rotations at the places opposed to each other with the axis of symmetry become reverse to each other, and the driven bodies are energized toward that axis from both sides of the axis of symmetry, whereby which receives unidirectional driving force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator, and more particularly to an ultrasonic actuator which generates ultrasonic vibration by an electro-mechanical energy conversion element.

[0002]

2. Description of the Related Art The present applicant has previously filed Japanese Patent Application No. 4-32109.
In No. 6, we proposed an ultrasonic actuator that can generate translational motion.

An outline of the configuration and principle of an ultrasonic transducer used in the ultrasonic actuator described in Japanese Patent Application No. 4-321096 will be described with reference to FIG.

As shown in FIG. 9, an ultrasonic transducer 71
Is the two laminated piezoelectric bodies 75 and the three holding elastic bodies 72a.
It is sandwiched so as to match the stacking direction, and is further fixed to one end surface of the rectangular parallelepiped elastic body 72 with a screw 72b, and a sliding member is provided on the other end surface of the elastic body 72 which is the antinode of vibration. 73 is fixed.

When a sinusoidal voltage is applied to the laminated piezoelectric body 75 of the ultrasonic oscillator 71, two kinds of vibrations are simultaneously excited in the elastic body 72, and the displacements of the two kinds of vibrations are combined to generate a sliding motion. The moving member 73 vibrates along an elliptical locus.
Then, when a driven body (not shown) is pressed against the sliding member 73, the driven body is translated by receiving a driving force from the vibration of the elliptical locus.

The two types of vibrations excited by the elastic body 72 will be described with reference to FIGS.

FIG. 10 shows a resonant longitudinal vibration which is a simple stretching motion. FIG. 11 shows a resonant bending vibration that is a transverse standing wave that is a transverse elastic wave propagating in the direction of expansion and contraction. The length and height of the elastic body 72 are set so that the primary resonance frequency of the stretching vibration and the frequency of the secondary standing wave of the transverse wave match.

Therefore, the displacements of the above two types of vibrations are combined only by applying the vibration of the frequency to the laminated piezoelectric material 75 of FIG. 10, and the mass point is elliptic at the antinode of the standing wave of the transverse wave. It vibrates along the trajectory. Therefore, when the sliding member 73 is provided at this position and the driven body is pressed against this, the driven body is translated by the action of the elliptical vibration.

An ultrasonic actuator using such an ultrasonic vibrator 1 performs a rectilinear motion, and a strong thrust force is directly obtained in the same rectilinear direction so that a reduction mechanism is not required. In addition, it has a number of excellent features that fine step driving on the order of nanometers is possible by inputting a burst wave.

The present applicant has further filed Japanese Patent Application No. 5-79814.
Issue, we proposed a micromanipulator system using the ultrasonic actuator.

According to the proposal described in Japanese Patent Application No. 5-79814, an ultrasonic wave is used as a driving source in a micromanipulator for performing cell manipulation such as gene injection into cells or measurement of nerve cell potential. An actuator is used, and a host such as a personal computer is combined with this to form a system. This makes it possible to quantitatively control the operating conditions of the ultrafine needle-shaped capillaries that perform cell manipulations at the tip, and to perform difficult cell manipulations easily and with good reproducibility without requiring skill. Is something that can be done.

In such a micromanipulator, it is necessary to generate minute displacements of the submicron order at various speeds, and moreover, this must be positioned with high accuracy. Such performance is not desirable for a drive mechanism using a conventional electromagnetic motor or the like, but since the ultrasonic actuator described above can generate a displacement on the order of nanometers with good reproducibility, it meets such requirements. It was a response with a margin.

FIG. 8 is an exploded perspective view showing an ultrasonic actuator using the ultrasonic vibrator 71 upside down, and an example described in the above-mentioned Japanese Patent Application No. 5-79814 will be described with reference to this drawing. To do.

The ultrasonic oscillator 71 as described above is provided with a shaft 74 as a supported portion projecting from a position serving as a node of vibration of the standing wave, and the shaft 74 is freely rotatable on the support body 52. Supported by. More specifically, the support body 52 has guide posts 54 protruding from both ends toward a frame body 51 described later, and a pair of sandwiching plates 53 are fixed to both side surfaces. A hole 53a is formed in the holding plate 53,
The ultrasonic transducer 71 is rotatably supported by penetrating the shaft 74 through the hole 53a. Therefore, the pressing force is evenly applied to the two sliding members 73 of the ultrasonic transducer 71.

The frame body 51 supports the ultrasonic transducer 71 via the support body 52, and the driven body 6 to be described later.
This is a member that supports 1 for translational movement. That is, the frame body 51 supports the guide pillars 54 of the support body 52 in the pair of holes 55 through the ball bushes 56, and the support body 52 is thereby supported by the ultrasonic transducer 71.
It can be translated only in the direction that urges.

A part 57 of the frame body 51 extends to the side opposite to the driven body 61 with the support body 52 interposed therebetween,
A pedestal 58 is provided between a part 57 of the frame 51 and the support 52.
The coil spring 59 is inserted and attached via the so as to apply a pressing force for urging the ultrasonic transducer 71. The pedestal 58 is a member that can adjust the amount of pressing force applied to the ultrasonic transducer 71 by the coil spring 59.

The driven body 61 is movably supported by a part of the frame body 51 such that its convex portion 62 is sandwiched by a pair of cross roller guides 63, and is translated only in a single direction. It is freely movable. This driven body 61
A sliding plate 64 for contacting the sliding member 73 of the ultrasonic transducer 71 is fixedly provided on the upper surface of the.

The ultrasonic transducer 71 is a coil spring 5
The sliding plate 64 is biased by the pressing force of 9, and the sliding plate 64 is displaced by the action of the elliptical vibration of the sliding member 73. A capillary (not shown) is fixed to the driven body 61 to which the sliding plate 64 is fixed, and the capillary can be finely driven by this.

[0019]

However, when performing patch clamp using a micromanipulator, the preamplifier must be placed on the movable portion of the manipulator. The preamplifier has a dead weight of, for example, about 100 g.
Therefore, if the weight of the movable portion of the manipulator itself is taken into consideration, the payload of the ultrasonic actuator needs to be 200 gf or more. The ultrasonic actuator as shown in FIG. 8 has a starting thrust of 4 when driven by a continuous sine wave.
Although it was about 00 gf, when the drive by the burst wave was performed in order to perform the precise position control and the speed control, a sufficient thrust could not always be obtained. That is, there is a problem that the function as a micromanipulator may not be sufficiently exerted because the thrust force during driving by the burst wave is not sufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a compact ultrasonic actuator capable of obtaining a large driving force.

[0021]

In order to achieve the above-mentioned object, an ultrasonic actuator according to the present invention comprises an electro-mechanical energy conversion element for generating ultrasonic vibration and an operation of the electro-mechanical energy conversion element. An ultrasonic actuator comprising: an elastic body that receives and generates elliptical vibration; and a driven body that is biased toward the elastic body and is translated by the elliptical vibration with respect to the elastic body. It is formed line-symmetrically, and the elliptical vibration is generated on both sides of the line-symmetrical axis of symmetry, and the directions of rotation at the positions facing each other across the line of symmetry are opposite. By being urged toward the shaft from both sides, the driving force in one direction is received.

[0022]

Function: The electro-mechanical energy conversion element generates ultrasonic vibrations, and the elastic body receives the action of the electro-mechanical energy conversion element and faces the both sides of the line-symmetrical axis of symmetry with the axis of symmetry interposed. Generates an elliptical vibration in which the rotation direction of the elastic body is reversed, and the driven body which is biased toward the elastic body from both sides of the symmetry axis applies a driving force in one direction to the elastic body by the elliptical vibration. It receives and is translated.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a first embodiment of the present invention, FIG. 1 is a front view showing a configuration of an ultrasonic transducer used in an ultrasonic actuator, and FIG. 2 is an elastic body of the ultrasonic transducer. FIG. 3 is a front view showing the action of the ultrasonic transducer, FIG. 4 is a front view showing a method of urging the driven body to the ultrasonic transducer, and FIG. It is an exploded perspective view showing the constituted ultrasonic actuator.

As shown in FIG. 2, the elastic body 12 used in the ultrasonic transducer 1 of the first embodiment is a member formed in a substantially rectangular shape from a brass-based material and is centered from both end surfaces on the short side. A slightly longer cut portion 12a is provided along the symmetry axis K that is vertically symmetric toward the cut portion 12. The cut portion 12a is formed to have a narrow width by using a processing method such as wire cutting. As a result, the elastic body 12 is cut into a vertically symmetrical shape. Further, the elastic body 12 is integrally provided with two convex portions 12b projecting laterally at the central portion on the long side.

As shown in FIG. 1, with respect to such an elastic body 12, a laminated piezoelectric body 11a, which is an electric-mechanical energy conversion element, sandwiching the two convex portions 12b,
11b are adhered to each other, and further, these laminated piezoelectric bodies 11
A holding elastic body 12d is arranged from both sides of a and 11b,
The holding elastic body 12 is fixed by screwing a screw 12e.

Further, the elastic body 12 is the laminated piezoelectric body 11
The sliding member 13 is adhesively fixed to the a and 11b, and the shaft 14 is adhesively fixed at a position approximately in the middle of the two notches 12a so as to project laterally. The ultrasonic transducer 1 is configured.

As shown in FIG. 1, such an ultrasonic transducer 1 applies a sine wave to the laminated piezoelectric body 11a, and a sine wave whose phase is advanced by 90 ° with respect to this sine wave is laminated piezoelectrically. It is adapted to be applied to the body 11b.

As shown in FIG. 4, the two driven bodies 2h and 2i forming the driven body 2 are urged by the urging member 2j so as to sandwich the upper and lower sliding members 13 of the ultrasonic transducer 1. When urged, the driven bodies 2h and 2i integrally receive a thrust force to either the left or the right.

If the positive and negative of the phase difference between the two sets of sine waves are inverted and the laminated piezoelectric body 11b is a sine wave whose phase is delayed by 90 ° with respect to the laminated piezoelectric body 11a, the direction of thrust is reversed. The driven body 2 moves in the opposite direction.

In the ultrasonic actuator of the first embodiment, as shown in FIG. 5, the ultrasonic vibrator 1 is housed in a recess 2a provided in the driven body 2 so as to be held therein, and is pressed by a pressing member. Through the plates 5 and 9, positioning is performed between the two bases 4 and 8 which are the bases of the ultrasonic actuator to form the main part.

The driven body 2 is a substantially rectangular plate-like member, and has the rectangular recess 2a for accommodating the ultrasonic transducer 1 as described above, and the central portion of the recess 2a has a rectangular hole. 2b is provided. Further, a pair of leaf springs 2d is attached to the upper edge portion inside the recess 2a,
It has an elastic force in the direction shown by arrow E in FIG. Therefore, the ultrasonic transducer 1 is vertically sandwiched by the leaf springs 2d in the recess 2a.

The driven body 2 is also provided with a pair of cross roller guides 3 at the upper and lower ends which are the long sides of the rectangular shape. The cross roller guide 3 connects the driven body 2 and the base plate 4 so that they can move in translation, so that the driven body 2 can move relative to the base plate 4 only in the direction indicated by arrow A in FIG. It is supported for translational movement.

The bases 4 and 8 are rectangular plate-like members each having a convex portion 4f and a convex portion 8f in the longitudinal direction which come into contact with the cross roller guide 3. These bases 4, 8
Is provided with elongated holes 4a, 8a in a direction perpendicular to the movement direction of the driven body 2 at substantially the center thereof.
In the vicinity of a and 8a, holes 4b and 8b for screwing, holes 4c and 8c through which one end of the torsion springs 7a and 7b, which are elastic members, can be finely moved, and holes for holding the torsion springs 7a and 7b. 4d, 8d and holes 4e, 8e for engaging the other ends of the torsion springs 7a, 7b are bored. The bases 4 and 8 are firmly fastened to each other by bolts (not shown), thereby forming a frame structure that supports the ultrasonic transducer 1 and the driven body 2 so as to wrap it. .

The pressing plates 5 and 9 are formed by forming a plurality of holes in a rectangular plate member. More specifically, the pressing plate 9 has a vertically long hole 9a provided at the center and a screw 1 at the lower right corner.
A hole 9b for attaching to the base 8 by means of 0 and a hole 9c for engaging one end of the torsion spring 7b are formed at the lower left corner. Similarly, the pressing plate 5 is also provided with an elongated hole 5a vertically elongated in the central portion, a hole 5b for attaching the base plate 4 with a screw 6, and a hole 5c for engaging one end of the torsion spring 7a. is doing. With this structure, the pressing plates 5 and 9 are rotatably attached to the bases 4 and 8 by the screws 6 and 10, and the pressing springs 7a and 7b of FIG. It is urged in the directions indicated by arrows B and B ′, respectively.

The shaft 14 of the ultrasonic transducer 1 is provided with a pressing plate 5
Through the long hole 5a and is connected to the long hole 4a serving as the reference surface of the substrate 4. Similarly, on the opposite side, the shaft 14 penetrates through the long hole 9a of the pressing plate 9 and engages with the long hole 8a serving as the reference surface of the base plate 8.

The pressing plates 5 and 9 have the long holes 5
The shaft 14 of the ultrasonic transducer 1 is pressed against the wall surfaces of the long holes 4a and 8a of the substrates 4 and 8 by a and 9a to position the ultrasonic transducer 1 with respect to the direction of translational movement of the driven body 2. There is.

As a modified example of the above-mentioned configuration,
If a commercially available cross roller guide is used instead of combining and positioning the long holes 5a and 9a and the long holes 4a and 8a, the positioning can be performed more firmly.

If a flat-bottomed groove is formed in a portion of the driven body 2 and the leaf spring 2d where the sliding member 13 abuts, and the sliding member 13 slides in the groove, Since the ultrasonic vibrator 1 moves without meandering, the operation is stable.

Next, the laminated piezoelectric body 11a and the laminated piezoelectric body 11b of the ultrasonic transducer 1 as described above have a phase of 90.
The operation in the case of applying the sine wave deviated from the angle will be described with reference to FIG. In the state shown in FIG. 3A, the laminated piezoelectric body 11a is in a stretched state and the laminated piezoelectric body 11b is in a shortened state.

The state shown in FIG. 3B is the same as that shown in FIG.
The state in which the phase is advanced by approximately 90 ° from the state shown in FIG.
b is also in a state of natural length.

The state shown in FIG. 3C is the same as that shown in FIG.
The phase is advanced by about 90 ° from the state shown in FIG. 3, the laminated piezoelectric body 11a is in a shortened state,
b is in a stretched state.

The state shown in FIG. 3D is the same as that shown in FIG.
The state in which the phase is advanced by approximately 90 ° from the state shown in FIG.
b is also in a state of natural length.

When the phase advances by approximately 90 ° from the state shown in FIG. 3 (D), the state returns to the state shown in FIG. 3 (A).

As is apparent from FIG. 3, the elastic body 12
A standing wave of stretching vibration and a secondary bending vibration is generated above and below, and each sliding member 13 fixed at a position which is an antinode of the standing wave of the secondary bending vibration performs an elliptic motion. At this time, since the standing wave of the bending whose direction is reversed in the vertical direction is generated, the direction of rotation of the elliptical vibration is reversed in the vertical direction. Thus, as shown in FIG. 4, when the ultrasonic transducer 1 is sandwiched between the driven bodies 2h and 2i from above and below, thrust forces in the same direction are generated in these two driven bodies 2h and 2i.

Here, as a configuration necessary for sandwiching, as is apparent from FIG. 5, only two leaf springs 2d are provided.
Can be realized by using the above, and unlike the conventional ultrasonic actuator described with reference to FIG. 8, a complicated and enormous urging means is not required. Further, since an elastic body having a similar volume is driven by using four laminated piezoelectric bodies that are twice as large as the conventional one, the amplitude of the elliptic vibration is increased and a stronger driving force can be obtained. .

According to the first embodiment as described above, since the elliptical vibrations of which the directions are opposite to each other can be generated above and below the elastic body, the ultrasonic actuator having a small size and a strong driving force can be obtained. Since no complicated biasing means is required,
It becomes a simple and thin ultrasonic actuator.

FIG. 6 shows a second embodiment of the present invention, and FIG. 6 is a front view showing an ultrasonic transducer. In the second embodiment, the same parts as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted. Only different points will be mainly described.

As shown in the figure, the elastic member 22 used in the ultrasonic transducer of the second embodiment has the notch 1 of the first embodiment.
A portion corresponding to 2a is cut out in a rectangular shape to provide a sandwiching portion 22a, and the laminated piezoelectric body 11c is sandwiched and held in the sandwiching portion 22a.

The point that the elastic body 22 is vertically symmetrical is the same as in the first embodiment.

As shown in FIG. 6, such an ultrasonic vibrator applies a sine wave to the laminated piezoelectric body 11a and also produces a sine wave whose phase is advanced by 90 ° with respect to this sine wave. It is adapted to be applied to 11b. Then, a sine wave whose polarity is inverted is applied to the added laminated piezoelectric body 11c.

When the voltage is applied in this manner, the elastic body 22
The upper part and the lower part with respect to the axis of symmetry are subjected to stretching / compressing forces by the laminated piezoelectric materials above and below them to excite vibration. Then, the sliding member 13 performs an elliptical vibration by performing substantially the same operation as described in FIG.

In this embodiment, since the upper and lower parts of the elastic body 22 are driven from the upper and lower sides, respectively, the vibration amplitude becomes large, and the vibration exciting force has a margin, so that the vibration is out of the resonance point. It is possible to drive by frequency.

According to the second embodiment as described above, substantially the same effect as that of the above-described first embodiment is obtained, and since the amplitude of the elliptical vibration is further increased, the thrust and the speed are increased. .

Further, since forced driving is possible, it is not necessary to exactly match the resonance points of the stretching vibration and the secondary bending vibration, and the dimensional intersection of the elastic body is made rough, thereby reducing the manufacturing cost. The effect is that you can

FIG. 7 shows a third embodiment of the present invention, and FIG. 7 is a front view showing an ultrasonic transducer. In the third embodiment, the same parts as those in the above-described first and second embodiments are designated by the same reference numerals and the description thereof will be omitted. Only different points will be mainly described.

As shown in the figure, the elastic member 32 used in the ultrasonic transducer of the third embodiment has the holding portion 2 of the second embodiment.
A portion corresponding to 2a is formed in a rectangular shape to form a rectangular hole 32a, and the laminated piezoelectric body 11d is sandwiched and held in the rectangular hole 32a. And, unlike the first and second embodiments, the laminated piezoelectric bodies 11a and 11b are not provided.

The operation of the third embodiment is almost the same as that of the above-mentioned first and second embodiments, and by applying voltages different in phase from each other by 90 ° to the laminated piezoelectric body 11d, the elastic body 32 is moved. The upper and lower parts are excited at the same time, and the sliding member 13
An elliptical vibration is generated in the, and the driven body is pressed into contact with the driven body.

According to the third embodiment as described above, while the same effect as that of the first and second embodiments described above is obtained and the amplitude of the elliptic vibration generated in the sliding member is slightly reduced, the laminated piezoelectric material is obtained. Since only two bodies are required and the shape of the elastic body is simple, the ultrasonic transducer can be manufactured in a small size and at low cost.

[0059]

As described above, according to the present invention, a compact ultrasonic actuator capable of obtaining a large driving force can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing the configuration of an ultrasonic transducer used in an ultrasonic actuator according to a first embodiment of the present invention.

FIG. 2 is a front view showing an elastic body of the ultrasonic transducer of the first embodiment.

FIG. 3 is a front view showing the operation of the ultrasonic transducer of the first embodiment.

FIG. 4 is a front view showing a method for urging a driven body to the ultrasonic transducer of the first embodiment.

FIG. 5 is an exploded perspective view showing an ultrasonic actuator configured using the ultrasonic vibrator of the first embodiment.

FIG. 6 is a front view showing an ultrasonic transducer according to a second embodiment of the present invention.

FIG. 7 is a front view showing an ultrasonic transducer according to a third embodiment of the present invention.

FIG. 8 is an exploded perspective view showing a conventional ultrasonic actuator which is inverted.

FIG. 9 is a front view showing a conventional ultrasonic transducer.

FIG. 10 is a diagram showing resonant longitudinal vibration excited in a conventional ultrasonic transducer.

FIG. 11 is a diagram showing resonant bending vibration excited in a conventional ultrasonic transducer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transducer 2 ... Driven body 11a, 11b, 11c, 11d ... Laminated piezoelectric body (electro-mechanical energy conversion element) 12, 22, 32 ... Elastic body 13 ... Sliding member K ... Symmetric axis

Front page continuation (72) Inventor Toshiharu Tsubata 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd. (72) Inventor Takashi Ouchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd.

Claims (1)

[Claims] 1. An electro-mechanical energy conversion element for generating ultrasonic vibrations, an elastic body for generating elliptical vibrations under the action of the electro-mechanical energy conversion element, and an elastic body biased toward the elastic body. In a ultrasonic actuator comprising: a driven body that is translated by the elliptical vibration with respect to the elastic body, the elastic body is formed in line symmetry, and the elliptical vibration has an axis of symmetry in the line symmetry. The direction of rotation of the portions that occur on both sides of the axis of symmetry and that face each other across the axis of symmetry is reversed, and the driven body is urged toward the axis from both sides of the axis of symmetry, thereby driving in one direction. An ultrasonic actuator that receives a force.