JP5039974B2 - Ultrasonic motor - Google Patents

Description

  The present invention relates to an ultrasonic motor using a cylindrical vibrator as a drive source.

  Conventionally, an ultrasonic motor is regarded as a high-power micromotor of millimeter order or less because it has a relatively simple structure in addition to a high torque output. It is used to adjust the focal length of the lens in focus.

  Various types of ultrasonic motors have been proposed depending on the application, and in particular, an ultrasonic motor using a cylindrical vibrator that flexures and vibrates is known as an ultrasonic motor capable of obtaining a high torque output. .

  In an ultrasonic motor using a cylindrical vibrator as a drive source, the tip of the vibrator is bent in a direction perpendicular to the longitudinal direction of the vibrator, and the tip of the vibrator is moved by moving the direction of bending of the vibrator. The bending vibration is generated by exciting the traveling wave on the end face.

In an ultrasonic motor using such a vibrator, a vibrator is fixed by suspending and fixing the node portion of the vibrator that vibrates and vibrates, or by attaching an O-ring to the node portion. The driving force can be taken out from both ends (see, for example, Non-Patent Document 1).
Takeshi MORITA, Minoru Kuribayashi KUROSAWA and Toshiro HIGUCHI "Cylindrical Micro Ultrasonic Motor Utilizing Bulk Lead Zirconate Titanate (PZT)" Japanese Journal of Applied Physics, Vol. 38, 1999, p. 3347-3350

  Although such ultrasonic motors are used in various applications, there is a need for ultra-small ultrasonic motors of the order of millimeters to expand the range of use, but scale down conventional ultrasonic motors. Therefore, there is a problem that it is extremely difficult to reduce the size and processing accuracy.

  Moreover, in the case of an ultrasonic motor using a vibrator that performs flexural vibration, it is extremely difficult to securely fix a miniaturized vibrator, and the energy of the flexural vibration is dissipated due to insufficient fixing. Therefore, it has been difficult to provide an ultrasonic motor with sufficient output characteristics.

  In view of the current situation, the present inventors have conducted research and development to provide a small ultrasonic motor that has desired output characteristics and is easy to handle, and has achieved the present invention.

In the ultrasonic motor of the present invention, a cylindrical shape having a hollow portion is provided, and a plurality of electrodes are provided on the outer peripheral surface along the circumferential direction, and electrodes are also provided on the inner peripheral surface. And a vibrator made of a piezoelectric body that vibrates along the circular trajectory around the axis line with respect to the base end by applying a base, and the base end is placed on the tip of the vibrator. Between the rotor and the bearing, a rotor in contact, a cylindrical casing that rotatably supports the rotor via a bearing at one end and the other end attached to the proximal end side of the vibrator And an urging member that presses the proximal end of the rotor against the distal end of the vibrator, and an ultrasonic motor that rotates the rotor in the axial direction along with the vibration of the vibrator. Is expanded toward the vibrator side And over tapered surface, and a cone-shaped insert to be inserted into the hollow portion of the vibrator projecting toward the vibrator-side inside of the tapered surface is provided, the tip end of the transducer to the tapered surface And the tip edge of the hollow portion of the vibrator is brought into contact with the peripheral surface of the conical insert .

Furthermore, the following points are also characteristic. That is,
(1) before SL and the angle between the outer peripheral surface of the tapered surface and the transducer, that the angle between the circumferential surface and the inner peripheral surface of the vibrator of the cone were the same angle.
(2) A cylindrical core material having a hardness higher than that of the piezoelectric body is provided on the inner peripheral surface of the vibrator, and an end portion of the core material on the tip side of the vibrator is a tip of the vibrator. And projecting end portion to form a projecting end portion, and the tip edge of the outer peripheral surface of the projecting end portion is brought into contact with the tapered surface.

  According to the present invention, as a cylindrical shape having a hollow portion, a plurality of electrodes are provided on the outer peripheral surface along the circumferential direction, and electrodes are also provided on the inner peripheral surface, and a predetermined voltage is applied to each electrode. A vibrator made of a piezoelectric body that vibrates the tip with respect to the base end along a circular locus around the axis, and a rotor arranged coaxially with the vibrator and having the base end in contact with the tip of the vibrator A cylindrical casing that rotatably supports the rotor via a bearing at one end and the other end mounted on the base end side of the vibrator, and a base end of the rotor provided between the rotor and the bearing. A small ultrasonic motor can be formed with high accuracy by using an ultrasonic motor that includes an urging body that is pressed against the tip of the motor and that rotates the rotor in the axial direction in accordance with the vibration of the vibrator.

  In particular, in the ultrasonic motor of the present invention, the casing is provided with a cylindrical casing that rotatably supports the rotor via a bearing at one end and is attached to the proximal end side of the vibrator at the other end. By using this, it is possible to easily arrange the ultrasonic motor at a predetermined position, and it is possible to improve the handleability of the ultrasonic motor.

  Further, the base end of the rotor is provided with a taper surface that is widened toward the vibrator side, and the output torque can be increased by bringing the tip edge of the vibrator into contact with the taper surface, Although it is small, an ultrasonic motor with high torque output can be obtained.

  In addition, when an insertion body that is inserted into the hollow portion of the vibrator is provided inside the tapered surface provided at the base end of the rotor, the rotor rotation shaft can be easily arranged on the axis of the vibrator that has a cylindrical shape. And the rotor can be easily placed at an appropriate position.

  In addition, the insertion body is a cone projecting toward the vibrator side, and when the tip edge of the hollow portion of the vibrator is brought into contact with the circumferential surface of the cone, the rotational movement of the vibrator tip is transferred to the rotor. It can be received by the taper surface of the base end and the peripheral surface of the cone, and the output torque can be further increased.

  In particular, the contact state between the vibrator and the taper surface can be obtained by setting the angle between the taper surface and the outer peripheral surface of the vibrator and the angle between the circumferential surface of the cone and the inner circumference of the vibrator to be the same angle. , And the contact state between the vibrator and the peripheral surface of the cone can be made as equal as possible, and it is possible to prevent the vibrator and the rotor base end from being in contact with each other. The rotor can be efficiently rotated.

  In addition, a cylindrical core material having a hardness higher than that of the piezoelectric body is provided on the inner peripheral surface of the vibrator, and the end portion on the tip side of the vibrator of the core material is projected from the tip of the vibrator to project the projecting end. When the tip end of the outer peripheral surface at the protruding end is brought into contact with the tapered surface, the base end of the rotor can be prevented from becoming a large diameter, and a further miniaturized ultrasonic motor can be obtained. be able to.

FIG. 1 is an exploded view of an ultrasonic motor according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the ultrasonic motor according to the embodiment of the present invention. FIG. 3 is a sectional view taken along line XX in FIG. FIG. 4 is an explanatory diagram of a substrate on which the ultrasonic motor according to the embodiment of the present invention is mounted. FIG. 5 is an explanatory view of a main part of an ultrasonic motor of a modification example. FIG. 6 is an explanatory diagram of a main part of an ultrasonic motor of a reference example. FIG. 7 is an explanatory diagram of a main part of an ultrasonic motor of a modification example. FIG. 8 is an explanatory diagram of a main part of an ultrasonic motor of a modification example.

Explanation of symbols

10 transducers
11 Vibration section
12 pedestal
13 Hollow part
14-1 First electrode
14-2 Second electrode
14-3 Third electrode
14-4 Fourth electrode
14-5 Internal electrode
20 Rotor
21 Contact part
22 Tapered surface
23 Insert
30 casing
31 Bearing
32 Coil spring
33 Insertion hole
34 Bearing support wall
35 Annular recess

  As shown in the exploded view of FIG. 1 and the longitudinal sectional view of FIG. 2, the ultrasonic motor of the present invention includes a vibrator 10 formed of a cylindrical piezoelectric body, and a base end at the tip of the vibrator 10. The rod-shaped rotor 20 arranged on the axis of the vibrator 10 while contacting the rotor 20 and the rotor 20 can be rotatably supported via a bearing 31 at one end and the other end can be attached to the base end side of the vibrator 10 And a coil spring 32 that is provided between the rotor 20 and the bearing 31 and that presses the proximal end of the rotor 20 against the distal end of the vibrator 10.

  In this embodiment, the vibrator 10 is made of a ceramic made of lead zirconate titanate having a hollow portion having a predetermined inner diameter. In particular, in the present embodiment, the vibrator 10 is first a cylindrical base made of cylindrical lead zirconate titanate ceramics having a diameter of 1.3 mm and a length of 3.4 mm, and one end side of this cylindrical base Is formed in a cylindrical body with a diameter of 0.8 mm and a length of 2.2 mm to form a thin vibrating portion 11, and then a through-hole with an inner diameter of 0.4 mm is drilled along the central axis of the cylindrical base. A cylindrical shape having a hollow portion 13 is provided. The vibrator 10 has a pedestal portion 12 having a relatively large diameter as the small-diameter vibration portion 11 is formed.

  Thereafter, a metal film is formed on the entire surface of the cylindrical substrate made of the lead zirconate titanate ceramic with the vibration portion 11 and the pedestal portion 12 formed by plating or the like. The metal film covering the surface is separated into a plurality along the circumferential direction of the cylindrical substrate. In the present embodiment, the metal film is separated by scanning the laser beam along the longitudinal direction of the cylindrical base body on the outer peripheral surface of the cylindrical base body. In particular, FIG. 3 which is an XX cross-sectional view of FIG. Thus, the vibrator 10 includes four electrodes, a first electrode 14-1, a second electrode 14-2, a third electrode 14-3, and a fourth electrode 14-4, along the circumferential direction of the cylindrical base. An electrode is formed.

  Also, the metal film at the tip, which is the end of the cylindrical base on the vibrating part 11 side, and the metal film at the base, which is the end on the base 12 side of the cylindrical base, are also removed and provided on the inner peripheral surface of the cylindrical base. The metal film is electrically separated from the first to fourth electrodes 14-1 to 14-4 provided on the outer peripheral surface of the cylindrical substrate, and the metal film provided on the inner peripheral surface of the cylindrical substrate is used as the internal electrode 14-5. .

  In the present embodiment, four electrodes of the first to fourth electrodes 14-1 to 14-4 are provided on the outer peripheral surface of the cylindrical base body. However, the number of electrodes is not limited to four, and a larger number of electrodes. May be provided. In the present embodiment, the first to fourth electrodes 14-1 to 14-4 and the internal electrode 14-5 are made of a nickel metal film. However, the electrodes 14-1 to 5 are made of a conductive film other than the nickel metal film. May be formed. Furthermore, in this embodiment, the vibrator 10 is formed of ceramics made of lead zirconate titanate, but may be formed of other piezoelectric materials.

  In this embodiment, the rotor 20 is made of a SUS cylinder having a predetermined diameter, and is provided with an abutting portion 21 that abuts the tip of the vibrator 10 with the end of one end as a base end. .

  The abutting portion 21 is a cylindrical body having a diameter larger than the diameter of the vibrating portion of the vibrator 10, and the bottom surface of the cylindrical body on the vibrator 10 side is partially cut away as shown in FIG. In addition, a mortar-shaped taper surface 22 is provided so as to expand toward the vibrator 10 side. As shown in FIG. 2, the rotor 20 is in contact with the edge of the outer peripheral surface of the vibrating portion 11 of the vibrator 10 on the tapered surface 22.

  Further, an insertion body 23 to be inserted into the hollow portion 13 of the cylindrical vibrator 10 is provided inside the tapered surface 22 on the bottom surface of the contact portion 21 on the vibrator 10 side.

  Moreover, the insertion body 23 is a cone projecting toward the vibrator 10 side, and on the peripheral surface 24 of this cone, as shown in FIG. 2, the end of the hollow part 13 in the vibration part 11 of the vibrator 10 It is in contact with the edge.

  In particular, the angle formed between the peripheral surface 24 of the cone and the inner peripheral surface of the vibrator 10 is the same as the angle formed between the tapered surface 22 and the outer peripheral surface of the vibrator 10.

  Thus, by setting the angle formed between the circumferential surface 24 of the cone and the inner circumferential surface of the vibrator 10 and the angle formed between the tapered surface 22 and the outer circumferential surface of the vibrator 10 to be the same angle, the circumference of the cone is increased. When the surface 24 and the taper surface 22 are in contact with the vibrator 10, respectively, it is possible to suppress the contact of one of them more strongly than the other, so that substantially the same contact state can be obtained.

  In this embodiment, the bearing 31 to be mounted on the rotor 20 is formed of a cylindrical body made of ethylene tetrafluoride resin, and the rotor 20 is inserted into the hollow portion 31a of the cylindrical bearing 31 so that the bearing 31 is mounted on the rotor 20. is doing.

  Since the bearing 31 made of ethylene tetrafluoride resin has a small frictional resistance on the surface, the rotor 20 can be smoothly rotated via the bearing 31 and can function as the bearing 31.

  Before inserting the rotor 20 into the bearing 31, the rotor 20 is inserted through the cylindrical coil spring 32, and then the rotor 20 is inserted through the bearing 31. As shown in FIG. The coil spring 32 is held in a sandwiched state between the portion and the bearing 31, and the contact portion 21 at the base end of the rotor 20 is pressed against the tip of the vibrator 10 by the bias of the coil spring 32. In the present embodiment, the coil spring 32 is used because of its small size, but any elastic body may be used. Instead of the coil spring 32, a disc spring or a cylindrical rubber tube is used. You can also.

  The casing 30 is a glass cylinder in the present embodiment, and includes a bearing support wall 34 provided with an insertion hole 33 through which the rotor 20 is inserted at one end, and an inner peripheral surface at the other end. An annular recess 35 is provided, and the pedestal 12 of the vibrator 10 can be inserted into the annular recess 35. In the present embodiment, the casing 30 has an outer diameter of 1.8 mm, an inner diameter of 1.0 mm, and a length of 5.8 mm, and the annular recess 35 portion has an inner diameter of 1.3 mm.

The casing 30 is not limited to glass, and may be anything as long as it satisfies the following conditions.
(1) The casing 30 is bent by the bending vibration generated in the vibrator 10, and the target bending vibration mode is not reduced.
(2) It is electrically insulated from the vibrator 10.
(3) It must be lightweight. That is, the density is small.

  In specifying the material of the casing 30, modal analysis was performed on the 12 kinds of materials by the finite element method. The results are shown in Table 1. In the table, Young's modulus, Poisson's ratio, and density are based on the “Science Chronology” (National Astronomical Observatory). The modal analysis result is a value obtained by dividing the maximum displacement of the casing 30 by the displacement of the tip of the vibration part. The judgment column in the table shows whether the modal analysis result meets the design condition, that is, the vibration mode condition. If the result is less than 0.2, ○, 0.2 or less than 0.4 is △, 0.4 or more. X indicates that ◯ is most preferable, and deteriorates in the order of Δ and ×.

  As a result of the modal analysis, the casing 30 is preferably made of a material having a Young's modulus of about 3 N / m 2 or more, desirably about 5 N / m 2 or more. As the Young's modulus is smaller than about 5 N / m 2, the casing 30 vibrates by resonating with the flexural vibration of the vibrator 10, and the driving force due to the flexural vibration is diminished, and vibration may propagate through the casing 30. there were. In this case, there was no correlation with the magnitude of the Poisson's ratio, and quartz glass and Pyrex (registered trademark) glass satisfied the above conditions when compared only with insulating materials.

  Since the vibration generated in the casing 30 is an elastic deformation of the casing 30, the results of comparison for each material by the value obtained by dividing the Young's modulus by the density are shown in Table 2. In Table 2, for the same materials as shown in Table 1, the values obtained by dividing the Young's modulus by the density are arranged in descending order. When the insulating materials are compared, the same results as in Table 1 are obtained. However, when a comparison is made including metal materials, it cannot be determined whether the condition is satisfied by a value obtained by dividing the Young's modulus by the density.

  In the ultrasonic motor, the rotor 20 to which the coil spring 32 and the bearing 31 are sequentially attached is inserted into the casing 30, the tip of the rotor 20 is inserted into the insertion hole 33 provided in the bearing support wall 34 of the casing 30, and the casing 30 The vibrator 10 is inserted therein, and the annular recess 35 of the casing 30 is fitted and integrated with the pedestal 12 of the vibrator 10. In the ultrasonic motor, the tip of the rotor 20 projected from the casing 30 is used as the output shaft.

  The contact portion 21 provided at the base end of the rotor 20 is provided with a mortar-shaped taper surface 22 that expands toward the vibrator 10 side, so that the rotor 20 can be easily placed on the axis of the vibrator 10. Can be arranged.

  Further, when the insertion body 23 to be inserted into the hollow portion 13 of the vibrator 10 is provided inside the tapered surface 22, the rotor 20 is regulated by the vibrator 10 by the insertion body 23, whereby the vibrator 10 The rotor 20 can be easily arranged on the axis.

  Since the casing 30 is attached by being fitted to the vibrator 10, the casing 30 can be attached very easily, and an extremely small ultrasonic motor can be accurately formed.

  When the casing 30 is fitted to the vibrator 10, the pedestal portion 12 of the vibrator 10 to which the casing 30 is fitted is not entirely covered with the casing 30, but as shown in FIG. The length of the pedestal 12 or the length of the annular recess 35 is set so that the lower end thereof is not covered with the casing 30.

  Thus, the lower end of the base part 12 is exposed from the casing 30, and the exposed first to fourth electrodes 14-1 to 14-4 are used as external connection terminals.

  For example, as shown in FIG. 4, the substrate 40 on which the ultrasonic motor is erected has a first substrate electrode 40-1 electrically connected to the first electrode 14-1, and a second electrode 14-2. A second substrate electrode 40-2 electrically connected to the third electrode 14-3, a third substrate electrode 40-3 electrically connected to the third electrode 14-3, and a fourth electrode electrically connected to the fourth electrode 14-4. The substrate electrode 40-4 is provided in a ring shape.

  When the ultrasonic motor is erected on the substrate 40, a solder paste is applied to each of the first to fourth substrate electrodes 40-1 to 40-4, and then the first electrode 14-1 is formed on the first substrate electrode 40-1. The second electrode 14-2 on the second substrate electrode 40-2, the third electrode 14-3 on the third substrate electrode 40-3, and the fourth electrode 14- on the fourth substrate electrode 40-4. 4 is arranged so that the solder paste solder can be reflowed to be electrically conductive.

  Note that the ultrasonic motor may be mounted not only on the substrate 40 but also on an appropriate socket (not shown) provided on the substrate 40.

  In the present embodiment, a potential signal of V0sinωt is applied to the first substrate electrode 40-1, a potential signal of −V0cosωt is applied to the second substrate electrode 40-2, and a potential signal of −V0sinωt is applied to the third substrate electrode 40-3. The potential signal of V0 cos ωt is input to the fourth substrate electrode 40-4. Note that the internal electrode 14-5 is equivalently 0 V as a voltage is applied to the first to fourth substrate electrodes 40-1 to 40-4.

  The respective potential signals are input to the first to fourth electrodes 14-1 to 4-4 via the first to fourth substrate electrodes 40-1 to 40-4, and the first to fourth electrodes 14-1 to 14-4 are based on the respective potential signals. By applying a potential, the vibrator 10 can be physically deformed.

  In particular, the vibrator 10 has a proximal end side connected to the substrate 40 as a thick pedestal portion 12 and a distal end side as a thin vibrating portion 11, so that the vibrator 10 has a distal end relative to the proximal end. Can be caused to rotate along a circular orbit around the axis at a frequency of ω / 2π.

  The rotor 20 has the contact portion 21 pressed against the tip of the vibrator 10 by the bias of the coil spring 32, and rotates in the direction opposite to the rotational direction of the bending vibration along with the bending vibration of the tip of the vibrator 10. A predetermined torque output can be obtained.

  The abutting portion 21 at the base end of the rotor 20 is not provided with the tapered surface 22 and the conical insert 23 as shown in FIGS. 1 and 2, but only the tapered surface 22 as shown in FIG. Even if it is provided, the rotor 20 can be sufficiently rotated.

  As described above, when only the tapered surface 22 is provided in the contact portion 21, the rotor 20 can be easily miniaturized as much as the conical insert 23 is not provided, and the vibrator 10 can be further miniaturized to further reduce the size of the ultrasonic motor. Even when the rotor 20, casing 30, bearing 31 and coil spring 32 are scaled down, the tapered surface 22 can be formed with high accuracy. Output can be obtained.

  As shown in FIG. 6, only the conical insert 23 may be provided at the contact portion 21 at the base end of the rotor 20.

  However, when the rotor 20 is rotationally driven through the conical insert 23, the rotor 20 tends to be correctly assembled to the casing 30, but a large output torque tends not to be obtained.

  That is, when V0 = 25V, the spring constant of the coil spring 32 is 0.01 N / mm, and the starting torque of the rotor 20 is measured with the coil spring 32 applying a preload of 5 mN to the rotor 20, as shown in FIG. In addition, when only the conical insert 23 is provided at the contact portion 21 of the rotor 20 base end, it was 0.61 μNm, whereas as shown in FIG. When only the tapered surface 22 was provided at the contact portion 21, the value was 1.0 μNm.

  The taper surface 22 is in contact with the outer periphery of the tip of the vibrator 10 where the vibrator 10 bends the most, so that the amount of displacement per unit time of the contact portion between the outer periphery of the tip of the vibrator 10 and the taper surface 22 It can be assumed that the starting torque can be improved.

  Further, as shown in FIGS. 1 and 2, a taper surface 22 and a conical insert 23 are provided at the contact portion 21 at the base end of the rotor 20, and the tip outer peripheral edge of the vibrator 10 is tapered surface 22. When the inner peripheral edge of the distal end of the hollow portion 13 of the vibrator 10 is brought into contact with the peripheral surface 24 of the cone of the insertion body 23, the starting torque was 1.7 μNm.

  In this case, it is considered that a large starting torque can be generated by the rotor 20 because the rotor 20 and the vibrator 10 are in contact at two locations.

  The tapered surface 22 is preferably abutted so that the angle formed with the outer peripheral surface of the vibration part 11 in the vibrator 10 is 30 to 60 °, and the conical peripheral surface 24 of the insert 23 is It is desirable that the vibrator 10 is brought into contact with the inner peripheral surface of the hollow portion 13 so that the angle is 30 to 60 °.

  If the angle is smaller than 30 °, the size of the contact portion 21 at the base end of the rotor 20 tends to increase in the length direction, and the weight of the contact portion 21 increases, so that the rotor 20 is difficult to rotate. Thus, the amount of rotation output from the rotor 20 may be reduced.

  On the other hand, if the angle is larger than 60 °, there is a possibility that the edge of the vibrator 10 slips on the taper surface 22 and the peripheral surface 24, and conversion that converts the bending vibration of the vibrator 10 into the rotational motion of the rotor 20. Efficiency may be reduced.

  Further, as described above, the angle formed by the peripheral surface 24 of the cone and the inner peripheral surface of the hollow portion 13 of the vibrator 10 and the angle formed by the tapered surface 22 and the outer peripheral surface of the vibration portion 11 of the vibrator 10 are determined. By setting the same angle, when the conical circumferential surface 24 and the tapered surface 22 are in contact with the vibrator 10, respectively, they can be brought into the same contact state, and the rotor 20 can be smoothly rotated. Therefore, torque can be taken out efficiently.

  The angle formed between the peripheral surface 24 of the cone and the inner peripheral surface of the hollow portion 13 in the vibrator 10 and the angle formed between the tapered surface 22 and the outer peripheral surface of the vibration portion 11 in the vibrator 10 are 40 to 50, respectively. The degree is most desirable.

  In this embodiment, the abutment portion 21 at the base end of the rotor 20 is provided with a conical insert 23. However, the insert 23 is not limited to a conical shape, for example, as shown in FIG. Thus, it may be formed in a hemispherical shape or may have an appropriate shape.

  Further, as a modification example, as shown in FIG. 8, a cylindrical core member 15 having higher strength than the piezoelectric body constituting the vibrator 10 is provided on the inner peripheral surface of the cylindrical vibrator 10. Moreover, the core material 15 is provided so as to protrude from the tip of the vibrator 10 toward the rotor 20, and the protruding portion of the core material 15 protruding from the vibrator 10 is defined as a protruding end portion 15 ′, and this protruding end portion 15 ′ portion The rotor 20 may be brought into contact with the rotor.

  In particular, by bringing the tip edge of the outer peripheral surface of the projecting end portion 15 ′ into contact with the tapered surface, the contact portion 21 of the rotor 20 can be made small in diameter, so the rotor 20 can be easily miniaturized. Further, it is possible to further reduce the size of the ultrasonic motor.

  For the core material 15, structural ceramics such as alumina ceramics and silicon nitride ceramics can be used. The core material 15 may be provided not only on the inner peripheral surface of the cylindrical vibrator 10 but also on the outer peripheral surface. In this case, the vibrator 10 does not necessarily have the pedestal 12 having a large diameter near the vibration part 11, and a necessary pedestal may be provided on the structural ceramics surrounding the vibrator 10.

  Because it can provide a small, high-power ultrasonic motor, medical devices that need to be miniaturized not only for lens position control in cameras but also for beating devices in consumer electronic products such as watches and endoscopic surgery It can be used as a drive device for an apparatus, a drive device for an industrial manufacturing machine, or a drive actuator for a micro robot.

Claims (3)

As a cylindrical shape having a hollow portion, a plurality of electrodes are provided on the outer peripheral surface along the circumferential direction, and electrodes are also provided on the inner peripheral surface, and a predetermined voltage is applied to each of the electrodes to form a base end. On the other hand, a vibrator made of a piezoelectric body that vibrates the tip along a circular locus around the axis,
A rotor arranged coaxially with the vibrator and having a base end in contact with the tip of the vibrator;
A cylindrical casing that rotatably supports the rotor via a bearing at one end and is attached to the base end side of the vibrator at the other end;
An urging body provided between the rotor and the bearing to press the proximal end of the rotor against the distal end of the vibrator;
In the ultrasonic motor that rotates the rotor in the axial direction along with the vibration of the vibrator,
At the proximal end of the rotor, a tapered surface that is widened toward the vibrator side, and a cone that is inserted into the hollow portion of the vibrator that protrudes toward the vibrator side inside the tapered surface. a body-shaped insert is provided, abut the leading edge of the transducer to the tapered surface, is abutted against the leading edge of the hollow portion of the vibrator on the peripheral surface of the cone-shaped insert An ultrasonic motor characterized by that. And angle formed between the outer peripheral surface of the vibrator and the tapered surface, super according to claim 1, wherein the angle formed between the circumferential surface and the inner peripheral surface of the vibrator of the cone were the same angle Sonic motor.   A cylindrical core material having a hardness higher than that of the piezoelectric body is provided on the inner peripheral surface of the vibrator, and an end of the core material on the tip side of the vibrator is projected from the tip of the vibrator. The ultrasonic motor according to claim 1, wherein a protruding end portion is formed, and a tip edge of an outer peripheral surface of the protruding end portion is brought into contact with the tapered surface.

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