JP4043497B2 - Method for adjusting vibration characteristics of ultrasonic vibrator and ultrasonic vibrator used therefor - Google Patents

Description

  The present invention relates to a method for adjusting vibration characteristics of an ultrasonic vibrator and an ultrasonic vibrator used therefor.

  Conventionally, an ultrasonic transducer using vibration of a piezoelectric element has been used. This ultrasonic transducer is not affected by magnetism, is small, has a high torque, has a high response speed, and has various advantages such as being stopped in a non-energized state. Yes. Therefore, the ultrasonic transducer is a promising element particularly for an autofocus drive mechanism of a mobile phone.

  However, since an ultrasonic transducer obtains a desired driving force by combining a plurality of types of vibrations, the desired driving characteristics can be obtained if the vibration characteristics change due to dimensional errors and manufacturing processes. It may not be possible.

Hereinafter, an ultrasonic transducer that obtains a desired driving force by combining a plurality of conventional vibrations will be described.
Note that an ultrasonic transducer described as an example generates elliptical vibration by combining longitudinal vibration (hereinafter referred to as “stretching vibration”) and flexural vibration (hereinafter referred to as “flexural vibration”). .

  The above-described ultrasonic vibrator obtains desired vibration characteristics by simultaneously generating stretching vibration and bending vibration in a diaphragm having a substantially rectangular planar shape. In order to generate the stretching vibration and the bending vibration at the same time, it is necessary to substantially match the resonance frequency of the stretching vibration generated in the diaphragm and the resonance frequency of the bending vibration. Therefore, the above-described ultrasonic vibrator is designed so that the resonance frequency of the stretching vibration and the resonance frequency of the bending vibration substantially coincide.

  Note that “the resonance frequency of the stretching vibration and the resonance frequency of the bending vibration substantially match” means that the resonance frequency of the stretching vibration is such that the driving force required for each product can be obtained. If the resonance frequency of the bending vibration is approximate, it means that the resonance frequency of the stretching vibration and the resonance frequency of the bending vibration need not be the same value.

  However, when the above-described ultrasonic vibrator is actually assembled, an error in the dimensions of the piezoelectric element and the diaphragm, an error in alignment between the piezoelectric element and the diaphragm, and an error in the dimensions of the electrode, the ultrasonic vibrator product Due to an error in the assembly position, the resonance frequency of the stretching vibration and the resonance frequency of the bending vibration do not substantially coincide with each other, so that desired vibration characteristics may not be obtained.

FIG. 20 shows an example of the ultrasonic transducer disclosed in Japanese Patent Application Laid-Open No. 2001-286167 and described above. According to this ultrasonic transducer, the stretching vibration and the bending vibration are simultaneously generated in the support 24, the protrusion 25, the adjustment unit 21, and the diaphragm 22. Thereby, elliptical vibration is generated in the diaphragm 22. The diaphragm 22 is provided with a protrusion 25, and elliptical vibration is also generated in the protrusion 25 in accordance with the elliptical vibration of the diaphragm 22. As a result, the driven body 23 in contact with the protrusion 25 rotates. The diaphragm 22 is provided with an adjusting unit 21 for adjusting the vibration characteristics. According to this ultrasonic transducer, it is possible to change the vibration characteristics by changing the shape of the adjustment unit 21.
JP 2001-286167 A

  In the method for adjusting the vibration characteristics of the ultrasonic transducer disclosed in Japanese Patent Laid-Open No. 2001-286167 described above, the relationship between the position where the adjustment unit 21 is provided and the position of the vibration node is not taken into consideration at all. For this reason, when the shape of the adjusting unit 21 is changed, the resonance frequencies of both the stretching vibration and the bending vibration are changed. That is, when the vibration characteristics are adjusted, all of the resonance frequencies of the plurality of vibrations change. Therefore, it is extremely difficult to substantially match the resonance frequencies of a plurality of vibrations.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to make it easy to substantially match the resonance frequencies of a plurality of vibrations even after the ultrasonic vibrator is assembled. An object of the present invention is to provide a method for adjusting the vibration characteristics of a sound wave vibrator and an ultrasonic vibrator used therefor.

The method for adjusting the vibration characteristics of an ultrasonic vibrator according to the present invention adjusts the vibration characteristics of an ultrasonic vibrator that drives a driven body by combining a plurality of types of vibration. Each of the plurality of types of vibrations has a vibration node whose amplitude is substantially zero. In this way, the operator of adjusting the characteristics of the vibration of the ultrasonic vibrator, one region a region including the position and the position in the vicinity of the section of one type of vibration of the sections of a plurality of types of oscillation When the region including the position of the node of another type of vibration different from one type of vibration and the vicinity thereof is defined as another region, the region is within one region and outside the other region. Change the physical quantity of a certain structure. Accordingly , the vibration characteristic having the vibration node in the other region is adjusted without substantially changing the vibration characteristic having the vibration node in the one region .

In general, in the manufacture of a product using an ultrasonic transducer, an error in the shape of the piezoelectric element, the diaphragm, or the electrode, a bonding error between the piezoelectric element, the diaphragm, and the electrode, and the final ultrasonic transducer Assembling errors to the product will occur. For this reason, at least one resonance frequency of the vibration resonance frequencies necessary for driving the driven body is different from the design value. As a result, there arises a problem that the resonance frequencies of all vibrations necessary for driving the driven body do not substantially match. In this case, according to the above-described method, the characteristics of one type of vibrations among a plurality of types of vibrations necessary for driving the driven body can be adjusted without changing the characteristics of other types of vibrations. Can do. Therefore, it is easier to make the resonance frequencies of all types of vibrations necessary for driving the driven body substantially the same as in the conventional method.

  The physical quantity of the structure includes at least one of mass, rigidity, shape, and internal stress, but may be any as long as the vibration characteristics can be adjusted. Further, the position in the vicinity of the vibration node may be any position as long as the position includes the position adjacent to the vibration node and the vibration characteristics can be adjusted substantially easily. For example, the position in the vicinity of the vibration node includes a peripheral region surrounding the vibration node when the vibration node is represented by a point when seen in a plan view.

The structure in one region may be a protrusion, and the physical quantity may be the physical quantity of the protrusion . According to this method, since the vibration characteristics can be adjusted by changing the physical quantity of the protruding portion, the vibration characteristics are adjusted compared to the method of adjusting the vibration characteristics by changing the physical quantities of other structures. Is easy.

Further, the physical quantity of the protruding portion may be changed by grinding. According to this method, the vibration characteristics can be adjusted by an extremely simple operation of grinding the protruding portion.

Further, the physical quantity of the protruding portion may be changed by heat treatment. According to this method, the vibration characteristics can be adjusted without changing the shape of the protruding portion.

Further, the physical quantity may be changed by adding a predetermined member to the protruding portion. Also by this method, it is possible to easily adjust the vibration characteristic having the vibration node in another region without substantially changing the vibration characteristic having the vibration node in one region .

Further, the physical quantity of the structure may be changed by providing a recess in one region . According to this method, it is possible to easily adjust the vibration characteristic having the vibration node in another region without substantially changing the vibration characteristic having the vibration node in one region .

  Further, the plurality of types of vibrations include stretching vibration and bending vibration, and any one of the vibration characteristics of the stretching vibration and the bending vibration may be adjusted. According to this, it is possible to easily adjust the vibration characteristics of a general ultrasonic transducer that performs elliptical vibration.

  Further, the bending vibration characteristic may be adjusted without adjusting the stretching vibration characteristic. According to this, the vibration characteristics can be easily adjusted as compared with the method of adjusting the vibration characteristics of the stretching vibration without adjusting the vibration characteristics of the bending vibration.

  In addition, the protrusion may function as a support protrusion for supporting the ultrasonic transducer. According to this method, it is not necessary to provide a support protrusion separately from the protrusion for adjusting the vibration characteristics. Therefore, the vibration characteristics of the ultrasonic transducer can be easily adjusted without increasing the number of parts.

The ultrasonic transducer of the present invention drives a driven body by combining a plurality of types of vibrations. Each of the plurality of types of vibrations has a vibration node whose amplitude is substantially zero. The region including the position of one type of vibration node and the position in the vicinity of one of the plurality of types of vibration nodes is defined as one region, and other types of vibration nodes are different from the one type of vibration. When the region including the position and the position in the vicinity thereof is set as another region, the vibration characteristic adjusting unit is provided in one region and outside the other region. The vibration characteristic adjustment unit adjusts the characteristics of vibrations having vibration nodes in other regions without substantially changing the vibration characteristics having vibration nodes in one region by changing the physical quantity of the structure. It has the structure which can do.

According to this structure, it becomes easy to adjust the characteristic of vibration having the vibration node in another region without substantially changing the characteristic of vibration having the vibration node in one region . As a result, it becomes easier to make the resonance frequencies of all the vibrations necessary for driving the driven body substantially coincide with each other as compared with the conventional structure.

If the above-described vibration characteristic adjusting unit has a protrusion, the vibration characteristic adjustment unit has a vibration node in one region by changing at least one of the shape, rigidity, mass, and internal stress of the protrusion . It becomes easy to adjust the vibration characteristics having vibration nodes in other regions without substantially changing the characteristics . Therefore, the adjustment operation of the vibration characteristics becomes easy.

Moreover, if the above-mentioned vibration characteristic adjustment part has a recessed part, the mass of a vibration characteristic adjustment part can be changed only by adding an object to a recessed part. Therefore, it becomes easy to adjust the vibration characteristic having the vibration node in another region without substantially changing the vibration characteristic having the vibration node in one region .

  The protrusion may function as a support protrusion that supports the ultrasonic transducer. According to this structure, it is not necessary to provide a protrusion for adjusting the vibration characteristics separately from the support protrusion. Therefore, the vibration characteristics of the ultrasonic transducer can be easily adjusted without increasing the number of parts.

  Further, the protrusion may function as a pressing protrusion for pressing the ultrasonic transducer against the driven body driven by the ultrasonic transducer. According to this structure, the vibration characteristic adjusting unit for adjusting the vibration characteristic and the pressing protrusion that presses the ultrasonic transducer against the driven body are made of the same component. Therefore, the vibration characteristics of the ultrasonic vibrator can be adjusted without increasing the number of parts of the ultrasonic vibrator.

  An ultrasonic transducer adjustment method and an ultrasonic transducer used therefor according to an embodiment of the present invention will be described with reference to FIGS. In the present specification, the vibration node means a region where the amplitude is substantially zero when only the vibration is generated. For example, a node of stretching vibration means a region where the amplitude of the main plate portion of the diaphragm is substantially zero when only stretching vibration occurs, and a node of bending vibration means only bending vibration. This means a region where the amplitude of the main plate portion of the diaphragm is substantially zero. The state where the amplitude is substantially zero includes a state where the ultrasonic transducer vibrates with an amplitude that is negligible for driving the driven body.

(Embodiment 1)
Hereinafter, a method for adjusting the vibration characteristics of the ultrasonic transducer according to the first embodiment of the present invention and the ultrasonic transducer used therefor will be described with reference to FIGS.

  The ultrasonic transducer of the present embodiment is one of two types of vibrations necessary for the above-described operation even after the ultrasonic transducer 1 that operates by combining a plurality of vibrations is assembled. It is possible to adjust the characteristics of one vibration independently of the other vibrations.

<Overall configuration>
First, an ultrasonic motor 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a plan view of the ultrasonic motor 100. As shown in FIG. 1, the ultrasonic motor 100 includes an ultrasonic vibrator 1 and a rotor 2 rotated by the ultrasonic vibrator 1. The rotor 2 is an example of a driven body of the present invention. Therefore, the driven body is not limited to the rotating body, and may be another operation.

  The ultrasonic vibrator 1 has a diaphragm 7. The diaphragm 7 has a supporting protrusion 3. A through hole 50 is provided in the supporting protrusion 3. The shaft 5 passes through the through hole 50. Moreover, the shaft 5 is being fixed to the support body 4, as FIG. 2 shows. The outer peripheral surface of the rotor 2 is in contact with one corner S of the four corners of the main plate portion 6. Although the rotor 2 is rotatably supported by the support body 4, the mechanism for that is not shown in figure.

  The ultrasonic vibrator 1 is provided with electrodes 9, 10, 11, 12, 17 and a piezoelectric element 8. The electrodes 9, 10, 11, 12, and 17 are electrically connected to a control device (not shown) so that a predetermined signal can be inputted.

  In the ultrasonic transducer 1 of the present embodiment, when a signal is input to the electrodes 9, 10, 11, 12, and 17, the piezoelectric element 8 vibrates. The vibration of the piezoelectric element 8 is transmitted to the main plate portion 6 of the diaphragm 7. As a result, the diaphragm 7 vibrates so that the corner portion S of the main plate portion 6 draws an elliptical orbit E. As a result, the rotor 2 in contact with the corner S moves along the circular path C. That is, the rotor 2 rotates around its rotation center axis.

<Ultrasonic transducer>
Next, the structure of the ultrasonic transducer 1 will be described in more detail with reference to FIGS. 2 and 3. 2 and 3 are a perspective view and an exploded perspective view of the ultrasonic transducer 1, respectively.

  As shown in FIGS. 2 and 3, the ultrasonic transducer 1 has a diaphragm 7. The diaphragm 7 includes a supporting protrusion 3 fixed to the shaft 5 and a main plate 6 that is formed integrally with the supporting protrusion 3 and rotates the rotor 2 by vibration.

  The main plate portion 6 is a flat plate member having a substantially rectangular planar shape having a width of 2 mm, a length of 9 mm, and a thickness of 0.2 mm. Further, the supporting protrusion 3 protrudes from the long side of the main plate 6 so as to extend from the center position of the long side of the main plate 6 along the short side direction of the main plate 6, and has a width of 1 mm and a length of 2 A flat plate-like member having a substantially rectangular planar shape with a thickness of 15 mm and a thickness of 0.2 mm.

  The supporting protrusion 3 is provided with a circular through hole 50 having a diameter of 0.6 mm. The diameter of the through hole 50 is 0.6 mm, which is the same as the diameter of the shaft 5. The distance from the center position of the long side of the main plate portion 6 to the center point of the through hole 50 is 1.0 mm. The piezoelectric element 8 is attached to each of the front and back surfaces of the main plate portion 6. The piezoelectric element 8 is a flat plate member having a rectangular planar shape with a width of 2 mm, a length of 8 mm, and a width of 0.2 mm. Further, the piezoelectric element 8 is fixed to the main plate part 6 via the electrode 17 so that the long side of the piezoelectric element 8 and the long side of the main plate part 6 coincide.

  The dimensions and shapes of the diaphragm 7 and the piezoelectric element 8 are not limited to the above dimensions and shapes, and may be other dimensions and shapes. Moreover, the material of the diaphragm 7 is not particularly limited, but is preferably a conductive material such as stainless steel. Moreover, although the support protrusion part 3 and the main plate part 6 may be formed of separate members, it is desirable that they are integrally formed of one member.

  The piezoelectric element 8 is made of lead zirconate titanate (PZT), but may be made of any material as long as the element vibrates when a voltage is applied. On one main surface of the piezoelectric element 8, electrodes 9, 10, 11, and 12 are attached. The electrodes 9, 10, 11, and 12 are flat members having the same rectangular planar shape. The electrodes 9, 10, 11, and 12 are provided in each of the four rectangular regions if one main surface of the piezoelectric element 8 is divided into substantially the same four rectangular regions. A substantially rectangular electrode 17 is provided on the other main surface of the piezoelectric element 8. The electrode 17 is a flat plate member having the same rectangular planar shape as the other main surface of the piezoelectric element 8.

  In the ultrasonic transducer 1 of the present embodiment, the two piezoelectric elements 8 are respectively provided on one main surface and the other main surface of the main plate portion 6 via electrodes 17.

  The two electrodes 17 are fixed to one main surface and the other main surface of the main plate portion 6 so that the long side direction thereof coincides with the long side direction of the main plate portion 6. The two electrodes 17 are each bonded to the main plate portion 6 with a conductive adhesive such as silver paste.

  Note that the electrode 17 may not be provided between the piezoelectric element 8 and the main plate portion 6 as long as the piezoelectric element 8 and the main plate portion 6 are bonded by a conductive adhesive. In this case, the conductive adhesive serves as the electrode 17. In particular, when the main plate portion 6 is made of a conductive material such as stainless steel as in the ultrasonic vibrator of the present embodiment, a signal of 0 V is always input to the electrodes 17 of the two piezoelectric elements 8 respectively. Therefore, if the piezoelectric element 8 and the main plate portion 6 are joined by a conductive adhesive, the main plate portion 6 can be formed even if the electrode 17 is not provided between the piezoelectric element 8 and the main plate portion 6. It can serve as the electrode 17.

  Further, the piezoelectric element 8 attached to one main surface of the diaphragm 7 and the electrodes 9, 10, 11, 12, and 17 attached to the piezoelectric element 8 and the other main surface of the diaphragm 7 are attached. The piezoelectric element 8 and the electrodes 9, 10, 11, 12, and 17 attached to the piezoelectric element 8 are arranged mirror-symmetrically in the thickness direction of the diaphragm 7. Therefore, the vibration characteristic of the piezoelectric element 8 on one main surface of the diaphragm 7 and the vibration characteristic of the piezoelectric element 8 on the other main surface of the diaphragm 7 are substantially the same. Therefore, the diaphragm 7 of the present embodiment vibrates in the in-plane direction. Further, since the main plate portion 6 of the diaphragm 7 is rectangular, the corner portion S of the diaphragm 7 vibrates elliptically in the above-described in-plane direction.

  If the object of the present invention can be achieved, the piezoelectric element 8 and the electrodes 9, 10, 11, 12, and 17 attached to one main surface of the diaphragm 7, and the diaphragm 7 The piezoelectric element 8 and the electrodes 9, 10, 11, 12, and 17 attached to the other main surface may have an asymmetric structure or may be asymmetrically arranged.

  Next, a method for driving the ultrasonic transducer 1 of the present embodiment will be described with reference to FIGS. When the ultrasonic transducer 1 is driven, a predetermined signal is input to the electrodes 9, 10, 11, 12, and 17 from a control device (not shown) provided outside. A signal (applied voltage) input to the electrodes 9, 10, 11, 12, and 17 positioned on one main surface side of the diaphragm 7 is positioned on the other main surface side of the diaphragm 7. The signals (applied voltages) input to the electrodes 9, 10, 11, 12, and 17 are input mirror-symmetrically via the main plate 6. However, if the object of the present invention can be achieved, a signal (applied voltage) input to the electrodes 9, 10, 11, 12, and 17 positioned on one main surface side of the diaphragm 7 and The signal (applied voltage) input to the electrodes 9, 10, 11, 12, and 17 positioned on the other main surface side of the diaphragm 7 may be asymmetric.

  As shown in FIG. 3, the electrode 9 and the electrode 12 are connected, and the same signal (φ1) is input. The electrode 10 and the electrode 11 are connected, and the same signal (φ2 ) Is entered. Therefore, the signal input to the electrodes 9, 10, 11, and 12 has four modes (A), (B), (C), and (D) as shown in FIG. . In FIG. 4, the entire outer shape of the electrodes 9, 10, 11, and 12 in a non-vibrated state is drawn by a broken line, and the electrodes 9, 10, 11, and Each of the 12 shapes is drawn with a solid line. Further, as shown in FIG. 5, the signals input to the electrode 9 and the electrode 11 and the signals input to the electrode 10 and the electrode 12 have a difference of 90 degrees in the phase, but the same Has amplitude and frequency.

  The main plate portion 6 of the ultrasonic transducer 1 described above performs vibration in combination with the stretching vibration shown in FIG. 6 and the bending vibration shown in FIG. According to the stretching vibration shown in FIG. 6, the main plate portion 6 of the diaphragm 7 is compressed or expanded in the long side direction as indicated by the white arrow. Thereby, the corner | angular part S vibrates in a long side direction. On the other hand, according to the bending vibration shown in FIG. 7, the diaphragm 7 changes from one S-shape to another S-shape that is mirror-symmetrical to it. Thereby, the corner | angular part of the main-plate part 6 of the diaphragm 7 vibrates in a short side direction, as shown by the white arrow.

  When the main plate portion 6 vibrates and contracts, as can be seen from FIG. 4, since the amplitude in the long side direction is extremely large relative to the amplitude in the short side direction, the corner portion S substantially vibrates in the long side direction. However, when the main plate portion 6 is bent and vibrated, the difference between the amplitude in the long side direction and the amplitude in the short side direction is not so large, so the corner portion S is actually inclined according to the electrode shape. Vibrate in the direction.

  When a voltage changing at the same frequency as the resonance frequency of the stretching vibration is applied to each of the electrodes 9, 10, 11, and 12 with the same phase, the main plate 6 is moved in the direction indicated by the arrow in FIG. 6. , Perform stretching vibration. In addition, a voltage (positive) that changes at the same frequency as the resonance frequency of the bending vibration is applied to each of the electrodes 9 and 11 in the same phase, and a voltage (negative) having an opposite phase to the electrodes 9 and 11 is applied to the electrodes. When applied to each of 10 and 12, the main plate portion 6 performs bending vibration as indicated by arrows in FIG. A reference potential (0 V) is always applied to each of the two electrodes 17.

  In FIGS. 6 and 7, the position X of the expansion vibration node and the position Y of the bending vibration node are indicated by hatching, respectively. The vibration node is a position in the main plate 6 where the amplitude is substantially zero. The shape of the electrode is not limited to a rectangle, and any shape may be used as long as the ultrasonic transducer 1 can generate both stretching vibration and bending vibration.

  Further, according to the conventional ultrasonic vibrator 1, the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration are not substantially the same as shown in FIG. 8, that is, shifted by Δφ. It is extremely difficult to reduce the deviation Δφ. This is because in adjusting the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration, one of them could not be changed independently of the other.

  However, according to the structure of the ultrasonic transducer 1 of the present embodiment, it is easy to reduce the deviation Δφ for the following reason. According to the structure of the ultrasonic transducer 1 described above, as shown in FIG. 6, the supporting protrusion 3 is provided at the position X of the node of the stretching vibration. If at least one of the physical quantities of the structure of the supporting protrusion 3 such as the shape, rigidity, mass, and internal stress is changed, the flexural vibration is not changed without changing the vibration characteristics of the stretching vibration. Characteristics can be changed. Therefore, it is easy to substantially match the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration.

  A voltage having the same frequency as the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration is applied to the electrodes 9 and 11, and the electrodes 9 and 11 have the same frequency and the phase is +90 degrees. A shifted voltage is applied to the electrodes 10 and 12. Thereby, stretching vibration and bending vibration are alternately generated every quarter of one cycle of the AC voltage input to the electrode. As a result, the corner portion S of the main plate portion 6 that is in contact with the rotor 2 performs elliptical vibration as indicated by reference numeral E in FIG.

  When a voltage having the same frequency as that of the electrodes 9 and 11 and having a phase shifted by −90 degrees is applied to the electrodes 10 and 12, an ellipse in a direction opposite to the direction indicated by the reference symbol E in FIG. Vibration occurs. In addition, if the phase of one of the signals input to the electrodes 9 and 11 and the electrodes 10 and 12 changes by 180 degrees with the rotor 2 rotating in a certain direction, the ultrasonic transducer The rotation direction of the rotor 2 in contact with the corner portion S of 1 is reversed.

  As shown in FIG. 9, the ultrasonic transducer 1 is located at the position Y of the bending vibration node shown in FIG. 7 or in the vicinity thereof, and the expansion vibration shown in FIG. You may have the adjustment protrusion 20 for adjusting a vibration characteristic in positions other than the position Y of a node, or its vicinity. However, the adjustment protrusion 20 may be formed as a part of the piezoelectric element 8 or the diaphragm 7 or may be formed by adding another material to the piezoelectric element 8 or the diaphragm 7.

  According to the ultrasonic transducer 1 having the structure shown in FIG. 9, the adjustment protrusion 20 is ground or heated, or some member is added to the adjustment protrusion 20, so that the resonance frequency b of the bending vibration is obtained. The resonance frequency a of the stretching vibration can be changed without changing the value. Therefore, the phase shift between the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration can be easily reduced.

<Method for adjusting vibration characteristics of ultrasonic transducer>
In the ultrasonic motor 100, in order to obtain the maximum driving efficiency, the ultrasonic vibrator 1 is assembled and assembled at a predetermined position of the ultrasonic motor 100. It is necessary that the resonance frequency b substantially matches. However, even in the ultrasonic vibrator 1 designed so that the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration substantially coincide with each other, an error in the dimensions of the piezoelectric element 8 or the diaphragm 7, piezoelectricity Due to factors such as errors in alignment between the element 8 and the diaphragm 7 and errors in the dimensions of the electrodes, the ultrasonic vibrator actually assembled and assembled in the ultrasonic motor 100 as shown in FIG. There may be a deviation Δφ between the resonance frequency a of the stretching vibration 1 and the resonance frequency b of the bending vibration. In FIG. 8, the horizontal axis indicates the frequency f (= 1 / T), and the vertical axis indicates the amplitude of vibration in the long side direction of the stretching vibration and the amplitude F of vibration in the short side direction of the bending vibration.

  FIG. 10 shows the result of the simulation performed by the present inventor. The length L1 of the supporting protrusion 3 and the change in the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration of the ultrasonic vibrator 1 are shown in FIG. Showing the relationship. As shown in FIG. 10, the resonance frequency b of the bending vibration of the ultrasonic vibrator 1 decreases approximately linearly as the length L1 of the supporting protrusion 3 increases, The resonance frequency a is substantially constant.

  The portions shown by hatching in FIGS. 6 and 7 correspond to the node position X of the stretching vibration and the node position Y of the bending vibration. The supporting protrusion 3 is provided at a position X of the expansion / contraction vibration node generated in the main plate 6 or a position in the vicinity thereof, and is provided at a position away from the position Y of the bending vibration node or in the vicinity thereof. ing. Therefore, when the length L1 of the supporting protrusion 3 is changed, the resonance frequency a of the stretching vibration does not change, but the resonance frequency b of the bending vibration changes.

  After the ultrasonic vibrator 1 is attached to a predetermined position of the ultrasonic motor 100, the shape and mass thereof can be changed by grinding the support protrusion 3. Thereby, only the resonance frequency b of the bending vibration can be adjusted in a state where the resonance frequency a of the stretching vibration is substantially constant. As a result, it becomes easy to substantially match the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration. Further, instead of changing the shape and mass of the support protrusion 3, the resonance frequency a of the stretching vibration can be kept constant by changing the physical properties such as rigidity of the support protrusion 3 by heat treatment such as annealing. In this state, it is easy to adjust the resonance frequency b of the bending vibration.

  Next, a method for adjusting the vibration characteristics of the ultrasonic transducer 1 by cutting the open end of the support protrusion 3, that is, by changing the shape and mass of the support protrusion 3 will be specifically described. Is done.

  When the assembly is performed and the resonance frequency b of the bending vibration of the ultrasonic vibrator 1 assembled at a predetermined position of the product is lower than the resonance frequency a of the stretching vibration, the resonance frequency a of the stretching vibration and the bending vibration In order to substantially match the resonance frequency b, it is necessary to increase the resonance frequency b of the bending vibration to the resonance frequency a of the stretching vibration.

  In the present embodiment, as shown in FIG. 11, the open end of the support protrusion 3 is scraped and the support protrusion 3 is shortened to increase the resonance frequency b of the bending vibration, thereby causing the stretching vibration. It is made to correspond to the resonance frequency a. According to this method, it is possible to easily adjust the vibration characteristics of the ultrasonic transducer 1. In addition, since the support protrusion 3 is not ground between the through hole 50 of the shaft 5 and the main plate portion 6, the vibration characteristics of the ultrasonic transducer 1 are maintained while the strength of the support protrusion 3 is maintained. Can be adjusted.

  Also, as shown in FIG. 12, a recess 55 is provided at each of two positions separated by the same distance from the center position of the through hole 50 provided in the support protrusion 3, and the shape of the support protrusion 3 is formed. And the mass may be varied. According to this, only the resonance frequency b of the bending vibration can be changed without changing the resonance frequency a of the stretching vibration.

  Further, as shown in FIG. 8, the two concave portions 55 are formed by grinding at positions that are opposed to each other through the center position of the through hole 50 and that are at an equal distance from the center position of the through hole 50. The Accordingly, it is possible to change the resonance frequency of the bending vibration by reducing the moment of inertia in the bending vibration. In addition, when the recessed part 55 becomes large too much by grinding, a vibration characteristic may be adjusted again by embedding a certain member in the recessed part 55. FIG.

  Next, a method of adjusting the vibration characteristics of the ultrasonic transducer 1 by changing the rigidity of the support protrusion 3 by heating the support protrusion 3 will be described. After the supporting protrusion 3 is heated to about 700 degrees using a heating device (not shown), it is naturally cooled. Thereby, the rigidity of the support protrusion 3 is reduced. When the rigidity of the supporting protrusion 3 is reduced, the resonance frequency b of the bending vibration of the ultrasonic transducer 1 is reduced. Further, when the supporting protrusion 3 is heated to about 700 degrees by the heating device and then rapidly cooled in water, the rigidity of the supporting protrusion 3 increases, and the bending vibration of the ultrasonic vibrator 1 is increased. The resonance frequency b increases. As a heating device, it is desirable to use a device that can locally heat only the supporting protrusion 3 such as a laser. Further, the heating temperature needs to be equal to or higher than the transformation temperature of the material of the supporting protrusion 3. When stainless steel is used as the material of the diaphragm 7, the heating temperature is desirably about 700 degrees.

  Next, a method for adjusting the vibration characteristics of the ultrasonic transducer 1 by mounting the weight 13 on the support protrusion 3, that is, by adding a material having a predetermined mass to the support protrusion 3 will be described. .

  As shown in FIG. 13, when the stainless steel weight 13 is bonded to the support protrusion 3, the mass of the support protrusion 3 increases. When the mass of the support protrusion 3 increases, the moment of inertia of the support protrusion 3 in bending vibration increases. Therefore, the resonance frequency b of the bending vibration of the ultrasonic vibrator 1 can be reduced. However, the material of the weight 13 is not limited to stainless steel and may be any material.

  Similarly to the above-described supporting protrusion 3, bending vibration can also be caused by causing a change in at least one of the shape, rigidity, mass, and internal stress of the adjusting protrusion 20 shown in FIG. 9. It becomes easy to change only the resonance frequency b of the stretching vibration without changing the resonance frequency a.

(Embodiment 2)
<Overall configuration>
In the ultrasonic transducer of the present embodiment, the same components as those of the ultrasonic transducer of the first embodiment are the same as the reference numerals assigned to the ultrasonic transducer 1 of the first embodiment. Reference numerals are given and the description will not be repeated unless otherwise required.

  Also in the present embodiment, the vibration characteristics of the ultrasonic transducer 1 can be easily adjusted even after the ultrasonic transducer 1 is assembled.

  FIG. 14 is a plan view of the ultrasonic motor 100 of the present embodiment. As shown in FIG. 14, the ultrasonic motor 100 of the present embodiment includes an ultrasonic transducer 1 and a rotor 2.

  The ultrasonic transducer 1 according to the present embodiment is substantially the same as the ultrasonic transducer 1 according to the first embodiment described with reference to FIGS. 1 to 8, but a supporting protrusion via the main plate 6. 3 is different from the ultrasonic transducer 1 of the first embodiment in that the pressing protrusion 14 is provided so as to oppose to the ultrasonic transducer 1. One end of a linear rubber 15 is bonded to the pressing protrusion 14. The other end of the linear rubber 15 is fixed to a pressing mechanism provided outside (not shown). The linear rubber 15 pulls the pressing protrusion 14 against the pressing mechanism by the contraction force. Accordingly, the force with which the corner portion S of the ultrasonic transducer 1 presses the outer peripheral portion of the rotor 2 can be adjusted. That is, the contact force between the ultrasonic transducer 1 and the rotor 2 is adjusted by adjusting the contraction force of the linear rubber 15.

  Also in the ultrasonic motor 2 of the present embodiment, as in the ultrasonic motor 100 of the first embodiment, signals are sent to electrodes 9, 10, 11, 12, and 17 provided in the ultrasonic transducer 1 described later. Entered. Thereby, the corner | angular part S of the main board part 6 contact | abutted to the outer peripheral surface of the rotor 2 moves drawing the elliptical orbit E shown by FIG. As a result, the rotor 2 rotates around the rotation center axis along the circular orbit C.

<Ultrasonic transducer>
FIG. 15 shows a perspective view of the ultrasonic transducer 1 of the present embodiment. Of the constituent elements of the ultrasonic transducer 1, the shape, dimensions, arrangement, and constituent materials of the main plate portion 6, the piezoelectric element 8, the electrodes 9, 10, 11, 12, and 17 are the ultrasonic waves of the embodiment. Since it is the same as that of the vibrator 1, its description will not be repeated.

  However, in the present embodiment, the through hole 50 and the shaft 5 are not fixed. Therefore, the shaft 5 can rotate around its axis in the through hole 50 provided in the supporting protrusion 3. More specifically, the supporting protrusion 3 is restricted from moving in the direction in which the shaft 5 extends, but can rotate around the rotation center axis along the direction in which the shaft 5 extends. In addition, the axial movement of the shaft 5 of the supporting protrusion 3 is prevented from moving along the axial direction of the shaft 5 on each of the upper side and the lower side of the supporting protrusion 3. A restraining member (not shown) is provided. The pressing protrusion 14 has a substantially rectangular shape with a width of 1 mm and a length of 2.5 mm.

  In addition, since the driving method of ultrasonic transducer 1 of the present embodiment is the same as the driving method of ultrasonic transducer 1 of the first embodiment, description thereof will not be repeated.

  Further, the structure shown in FIG. 16 may be employed as the structure of the ultrasonic transducer 1. In the structure shown in FIG. 16, at least one of the positions near the flexural vibration node position X shown in FIG. 6 and away from the expansion vibration node position Y shown in FIG. The adjustment protrusion 20 is provided at a position of the piezoelectric element 8 or the main plate 6 even if the adjustment protrusion 20 is a part of the piezoelectric element 8 or the main plate 6. It may be added.

<Method for adjusting vibration characteristics of ultrasonic transducer>
FIG. 17 shows a simulation result performed by the inventors of the present application. The length L2 of the pressing protrusion 14 of the ultrasonic transducer 1, the resonance frequency a of the stretching vibration of the ultrasonic transducer 1, and the bending vibration are shown. The relationship with the resonance frequency b is shown. As shown in FIG. 17, as the length L2 of the pressing protrusion 14 is increased, the resonance frequency b of the bending vibration of the ultrasonic transducer 1 decreases approximately linearly. a is almost constant.

  The pressing projection 14 is provided at the position X of the expansion vibration node generated in the main plate 6 or in the vicinity thereof, and at a position away from the position Y of the bending vibration node or the vicinity thereof. Therefore, when the length L2 of the pressing protrusion 14 is changed, the resonance frequency b of the bending vibration can be changed without changing the resonance frequency a of the stretching vibration.

  After the ultrasonic vibrator 1 is attached to a predetermined position of the ultrasonic motor 100, the shape and mass of the pressing projection 14 are changed, so that the resonance frequency a of the stretching vibration is substantially constant and the bending vibration By adjusting only the resonance frequency b, the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration can be substantially matched.

  It is also possible to adjust the resonance frequency of the bending vibration by changing the physical properties of the pressing protrusion 14 such as rigidity using a technique such as annealing.

  Next, there is a specific method of adjusting the vibration characteristics of the ultrasonic transducer 1 by grinding the tip of the pressing projection 14 to change the shape and mass of the pressing projection 14 of the ultrasonic transducer 1. Explained.

  When the resonance frequency b of the bending vibration of the ultrasonic vibrator 1 assembled and installed at a predetermined position is lower than the resonance frequency a of the stretching vibration, the resonance frequency a of the stretching vibration and the resonance frequency b of the bending vibration Therefore, it is necessary to increase only the resonance frequency b of the bending vibration so as to substantially match the resonance frequency a of the stretching vibration. As shown in FIG. 18, when the length L2 of the pressing protrusion 14 is shortened by grinding the tip of the pressing protrusion 14, the resonance frequency a of the stretching vibration is constant and the resonance frequency of the bending vibration is constant. b increases. Therefore, it is easy to substantially match the resonance frequency b of the bending vibration with the resonance frequency a of the stretching vibration.

  Next, a method of adjusting the vibration characteristics of the ultrasonic transducer 1 by applying heat treatment to the pressing projection 14 to change the rigidity of the pressing projection 14 of the ultrasonic transducer 1 will be described.

  The pressing protrusion 14 is heated to about 700 degrees using a heating device. Thereafter, natural cooling is performed. As a result, the rigidity of the pressing protrusion 14 is reduced. When the rigidity of the pressing projection 14 is reduced, the resonance frequency b of the bending vibration of the ultrasonic vibrator 1 is lowered.

  Further, when the pressing protrusion 14 is heated to about 700 degrees using a heating device and then rapidly cooled in water, the rigidity of the pressing protrusion 14 increases, and the ultrasonic transducer 1. The resonance frequency b of the bending vibration increases.

  As the heating device, it is desirable to use a device such as a laser that can locally heat only the pressing protrusion 14. The heating temperature needs to be equal to or higher than the transformation temperature of the material of the pressing protrusion 14. Therefore, when stainless steel is used as the material of the pressing protrusion 14, it is desirable that the pressing protrusion 14 is heated at a temperature of about 700 degrees.

  Next, a method of adjusting the vibration characteristics of the ultrasonic vibrator 1 by changing the mass of the pushing protrusion 14 of the ultrasonic transducer 1 when the weight 13 is mounted on the pressing projection 14 will be described. The

  As shown in FIG. 19, when the stainless steel weight 13 is bonded to the pressing protrusion 14, the resonance frequency b of the bending vibration is lowered while the resonance frequency a of the stretching vibration is constant. In addition, the material of the weight 13 is not limited to stainless steel, and may be a material other than stainless steel.

  Similarly to the support protrusion 3, by changing at least one of the shape, rigidity, and mass of the adjustment protrusion 20 shown in FIG. 16, the resonance frequency b of the bending vibration is changed. Only the resonance frequency a of the stretching vibration can be easily adjusted without changing it.

  In the above-described embodiment, the physical quantity of the protruding portion, which is a structure provided at the position of one of the plurality of types of vibration nodes or in the vicinity thereof, of the shape, rigidity, and mass The vibration characteristics are adjusted by changing at least one of them. However, as described above, the internal stress of the structure at or near the position of the vibration node is changed instead of the shape, rigidity, and mass of the structure provided at or near the position of the vibration node. It is possible to adjust the vibration characteristics. As a method of changing the internal stress, a method in which the structure at the position of the vibration node or in the vicinity thereof includes a dielectric and an electric field is applied to the dielectric from the outside.

  Further, in each of the above embodiments, the protrusion is provided so as to include the vibration node, but even if the protrusion is provided in the vicinity of the position of the vibration node, the vibration node and the protrusion If the distance between them is smaller than a predetermined amount, it is easy to adjust the vibration characteristics as compared with the conventional method. For example, in the case where the resonance frequency a of the stretching vibration is changed without changing the resonance frequency b of the bending vibration, a peripheral shape surrounding the node of the bending vibration expressed by a point when seen in a plan view is used. A protrusion may be formed on the region. For example, even if a pipe-like protruding portion surrounding a point as a vibration node of bending vibration is provided instead of the adjusting protruding portion 20, the vibration characteristics can be easily adjusted in the same manner as described above. .

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a top view of the ultrasonic motor of an embodiment. 1 is a perspective view of an ultrasonic transducer according to an embodiment. It is a disassembled perspective view of the ultrasonic transducer | vibrator of embodiment. It is a figure for demonstrating four voltage modes applied to four electrodes attached to the piezoelectric element. 6 is a time chart for explaining that a phase of a signal for stretching vibration and a phase of vibration for bending vibration are shifted by 90 °. It is a figure which shows the aspect which the main board part of embodiment deform | transforms by expansion-contraction vibration. It is a figure which shows the aspect which the main board part of embodiment deform | transforms by bending vibration. It is a figure for demonstrating that the resonance frequency of a stretching vibration and the resonance frequency of a bending vibration do not correspond. It is the schematic showing the structure of the ultrasonic transducer | vibrator of embodiment. It is a graph which shows the relationship between the length of the protrusion part for support of embodiment, and the resonance frequency of expansion vibration, and the resonance frequency of bending vibration. It is a figure for demonstrating how to cut the protrusion part for support of embodiment. It is a figure which shows the recessed part provided in the protrusion part for support of embodiment. It is a figure for demonstrating the state by which the weight was installed in the protrusion part for support of embodiment. 6 is a plan view of an ultrasonic motor according to Embodiment 2. FIG. 6 is a perspective view of an ultrasonic transducer according to Embodiment 2. FIG. 6 is a schematic diagram illustrating a configuration of an ultrasonic transducer according to Embodiment 2. FIG. 6 is a graph showing the relationship between the length of a pressing protrusion of Embodiment 2, the resonance frequency of stretching vibration and the resonance frequency of bending vibration. It is a figure for demonstrating how to cut the protrusion part for pressing of embodiment. It is a figure which shows the state by which the weight was installed in the protrusion part for pressing of embodiment. It is the schematic which shows the structure of the ultrasonic transducer | vibrator shown in Unexamined-Japanese-Patent No. 2001-286167.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Ultrasonic vibrator, 2 Rotor, 100 Ultrasonic motor, 3 Protrusion part for support, 4 Support body, 5 Shaft, 6 Main plate part, 7 Vibration plate, 8 Piezoelectric element, 9, 10, 11, 12, 17 Electrode, 14 Protruding part for pressing, 15 Rubber, 20 Adjusting protruding part, 50 Through hole, 55 Recessed part, a Resonance frequency for stretching vibration, b Resonance frequency for bending vibration, C circular orbit, E elliptical orbit, S corner, X telescopic Vibration node position, Y Bending vibration node position, Δφ Phase shift.

Claims (14)

A method for adjusting the vibration characteristics of an ultrasonic vibrator that drives a driven body by combining a plurality of types of vibrations,
Each of the plurality of types of vibrations has a vibration node having an amplitude of substantially zero;
The region including the position of one type of vibration node of the plurality of types of vibration nodes and the position in the vicinity thereof is defined as one region, and other types of vibrations different from the one type of vibration. When the area including the position of the node and the vicinity thereof is set as another area, the physical quantity of the structure that is in the one area and outside the other area is changed to vibrate in the one area. A method for adjusting an ultrasonic transducer, wherein the characteristic of vibration having a vibration node in the other region is adjusted without substantially changing the characteristic of vibration having a node. The structure in the one region is a protrusion;
The method according to claim 1, wherein the physical quantity is a physical quantity of the protrusion.   The method of adjusting an ultrasonic transducer according to claim 2, wherein the physical quantity of the protruding portion is changed by grinding.   The method of adjusting an ultrasonic transducer according to claim 2, wherein the physical quantity of the protruding portion is changed by heat treatment.   The method of adjusting an ultrasonic transducer according to claim 2, wherein the physical quantity is changed by adding a predetermined member to the protrusion.   The method for adjusting an ultrasonic transducer according to claim 1, wherein a physical quantity of the structure is changed by providing a concave portion in the one region. The plurality of types of vibrations include stretching vibrations and bending vibrations,
The vibration characteristic of any one of the said stretching vibration and the said bending vibration is adjusted.
The method for adjusting an ultrasonic transducer according to claim 1.   The method for adjusting an ultrasonic transducer according to claim 7, wherein the characteristic of the bending vibration is adjusted without adjusting the characteristic of the stretching vibration.   The method for adjusting an ultrasonic transducer according to claim 2, wherein the protruding portion functions as a supporting protruding portion for supporting the ultrasonic transducer. An ultrasonic vibrator that drives a driven body by combining a plurality of types of vibrations,
Each of the plurality of types of vibrations has a vibration node having an amplitude of substantially zero;
The region including the position of one type of vibration node of the plurality of types of vibration nodes and the position in the vicinity thereof is defined as one region, and other types of vibrations different from the one type of vibration. When the region including the position of the node and the vicinity thereof is set as another region, a vibration characteristic adjusting unit is provided in the one region and outside the other region,
The vibration characteristic adjusting unit is configured to change a physical quantity of the structure so that a vibration characteristic having a vibration node in the one region is substantially unchanged without changing a vibration characteristic having the vibration node in the one region. An ultrasonic transducer having a structure capable of adjusting characteristics .   The ultrasonic transducer according to claim 10, wherein the vibration load adjustment unit has a protrusion.   The ultrasonic transducer according to claim 10, wherein the vibration characteristic adjusting unit has a recess.   The ultrasonic transducer according to claim 11, wherein the protruding portion functions as a supporting protruding portion that supports the ultrasonic transducer.   The ultrasonic transducer according to claim 11, wherein the protrusion functions as a pressing protrusion for pressing the ultrasonic transducer against a driven body driven by the ultrasonic transducer.

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