Rotor, stator, and ultrasonic motor

Abstract

Provided is a rotor capable of suppressing sticking.　A rotor 4 according to the present invention is used in an ultrasonic motor 1 comprising a stator 2 that has a vibrator 3 and a vibration generating element (piezoelectric element 13) provided on the vibrator 3, the rotor comprising: a rotor body 4A, and a sliding material 7 provided on the rotor body 4A and in contact with the vibrator 3. The sliding material 7 is made of carbon graphite.

Description

Rotor, stator and ultrasonic motor

[0001] The present invention relates to a rotor, a stator, and an ultrasonic motor.

[0002] Various ultrasonic motors have been proposed in the past that use piezoelectric elements to vibrate a stator. One example of an ultrasonic motor is disclosed in Patent Document 1 listed below. In this ultrasonic motor, a rotor is rotated by a traveling vibration wave generated in the stator.

[0003] The stator in Patent Document 1 is made of a ring-shaped piezoelectric body bonded to a ring-shaped elastic body. Vibration of the piezoelectric body generates a traveling vibration wave in the elastic body. Meanwhile, the rotor is made of a ring-shaped slider material bonded to a ring-shaped rotor base material. The slider material of the rotor is in contact with the elastic body of the stator. When the rotor rotates, the slider material slides on the surface of the elastic body. The slider material in Patent Document 1 is made of resin.

[0004] Japanese Patent Application Publication No. 3-074182

[0005] When an ultrasonic motor using a resin slider material is used in a high humidity environment, the rotor may stick to the stator, causing the stator and rotor to become fixed to each other, making it impossible to start the ultrasonic motor. This phenomenon is called "sticking."

[0006] When a slider material made of resin slides over the surface of a stator, the slider material generates wear particles that are broken down into small pieces by mechanical friction and low-molecular-weight components that are decomposed by frictional heat. The inventors discovered that the low-molecular-weight components generated by the slider material include water-soluble components. The inventors discovered that when a water-soluble component or a mixture of a water-soluble component and wear particles is exposed to moisture and then dries, it functions as an adhesive, thereby fixing the stator and rotor to each other. This can cause sticking.

[0007] If the motor is stuck, it will not be possible to start the ultrasonic motor even if a drive signal is applied, and therefore the sticking will be a fatal failure of the ultrasonic motor.

[0008] An object of the present invention is to provide a rotor, a stator, and an ultrasonic motor that can suppress sticking.

[0009] The rotor according to the present invention is a rotor used in an ultrasonic motor equipped with a stator having a vibrating body and a vibration generating element provided on the vibrating body, and comprises a rotor body and a sliding material provided on the rotor body and in contact with the vibrating body, the sliding material being made of carbon graphite.

[0010] The stator according to the present invention is a stator used in an ultrasonic motor having a rotor, and comprises a vibrating body, a vibration generating element provided on the vibrating body, and a sliding material provided on the vibrating body and in contact with the rotor, the sliding material being made of carbon graphite.

[0011] In one broad aspect of the ultrasonic motor according to the present invention, the motor is provided with a rotor configured according to the present invention, the vibrating body, and the stator having the vibration generating element provided on the vibrating body.

[0012] In another broad aspect of the ultrasonic motor according to the present invention, the motor includes a stator configured according to the present invention and the rotor.

[0013] The rotor, stator, and ultrasonic motor according to the present invention can suppress sticking.

[0014] FIG. 1 is a schematic front cross-sectional view of an ultrasonic motor according to a first embodiment of the present invention. FIG. 2 is a schematic plan view of a stator according to the first embodiment of the present invention. FIG. 3 is a schematic plan view of a rotor according to the first embodiment of the present invention. FIG. 4 is a schematic cross-sectional view taken along line II in FIG. 3. FIG. 5 is a schematic front cross-sectional view of a piezoelectric element according to the first embodiment of the present invention. FIG. 6 is a schematic plan view of a rotor according to a second embodiment of the present invention. FIG. 7 is a schematic plan view of a rotor according to a third embodiment of the present invention. FIG. 8 is a schematic plan view of a rotor according to a modified example of the third embodiment of the present invention. FIG. 9 is a schematic cross-sectional view of a portion of a rotor according to a fourth embodiment of the present invention, corresponding to the cross section taken along line II in FIG. 3. FIG. 10 is a schematic cross-sectional view of the rotor according to the fourth embodiment of the present invention, showing a state in which the portion shown in FIG. 9 is in contact with the vibrating body of the stator, and a traveling wave is generated in the stator. FIG. 11 is a schematic cross-sectional view of a portion of a rotor according to a modified example of the fourth embodiment of the present invention, corresponding to the cross section taken along line II in FIG. 3. Fig. 12 is a schematic bottom view of a stator according to a fifth embodiment of the present invention. Fig. 13 is a schematic bottom view of a stator according to a sixth embodiment of the present invention. Fig. 14 is a schematic cross-sectional view taken along line II-II in Fig. 13.

[0015] The present invention will be clarified below by describing specific embodiments of the present invention with reference to the drawings.

[0016] It should be noted that the embodiments described in this specification are merely examples, and partial substitution or combination of configurations is possible between different embodiments.

[0017] FIG. 1 is a schematic front cross-sectional view of an ultrasonic motor according to a first embodiment of the present invention.

[0018] The ultrasonic motor 1 has a stator 2, a rotor 4, and a shaft member 10. The stator 2 and the rotor 4 are in contact with each other. The rotor 4 is a rotor according to one embodiment of the present invention. The rotor 4 rotates due to traveling waves generated in the stator 2. The shaft member 10 rotates in conjunction with the rotation of the rotor 4. The central axis of rotation of the ultrasonic motor 1 is located at the portion where the shaft member 10 is provided. The specific configuration of the ultrasonic motor 1 will be described below.

[0019] FIG. 2 is a schematic plan view of the stator according to the first embodiment.

[0020] The stator 2 has a plate-shaped vibrating body 3. The vibrating body 3 has a disk shape. The vibrating body 3 has a first main surface 3a and a second main surface 3b. The first main surface 3a and the second main surface 3b face each other.

[0021] A through-hole 3c is provided in the center of the vibrating body 3. As shown in Fig. 1, a shaft member 10 is inserted through the through-hole 3c. The position of the through-hole 3c is not limited to the center of the vibrating body 3. The through-hole 3c may be located in a region including the central axis of rotation. Furthermore, the shape of the vibrating body 3 is not limited to a disk shape.

[0022] In this specification, the axial direction Z refers to the direction connecting the first main surface 3 a and the second main surface 3 b and along the central axis of rotation. In this embodiment, the axial direction Z is parallel to the direction in which the shaft member 10 extends. The shape of the vibrating body 3 as viewed from the axial direction Z may be a regular polygon such as a regular hexagon, a regular octagon, or a regular decagon. In this specification, the term "polygon" also includes cases in which the portions corresponding to the vertices are curved and cases in which the corners are chamfered. Hereinafter, the view from the axial direction Z may be referred to as a planar view.

[0023] The vibrating body 3 is made of an appropriate metal. However, the vibrating body 3 does not necessarily have to be made of metal. The vibrating body 3 may be made of other elastic materials such as ceramics or silicon material.

[0024] As shown in FIG. 2 , a plurality of piezoelectric elements 13 are provided on the first main surface 3 a of the vibrating body 3. The piezoelectric elements 13 are vibration generating elements of the present invention. In a plan view, the plurality of piezoelectric elements 13 are distributed in the circumferential direction. More specifically, the plurality of piezoelectric elements 13 are distributed along the circumferential direction of the traveling wave so as to generate a traveling wave that circulates around an axis parallel to the axial direction Z. A structure in the stator 2 in which a plurality of piezoelectric elements 13 are distributed in the circumferential direction and driven to generate a traveling wave is disclosed, for example, in International Publication No. 2010 / 061508. Therefore, a detailed description of the generation of the traveling wave will be omitted.

[0025] FIG. 3 is a schematic plan view of the rotor according to the first embodiment.

[0026] The rotor 4 has a rotor body 4A and a sliding member 7. The rotor body 4A has an annular shape in a plan view. A through hole 4c is provided in the center of the rotor body 4A. The shaft member 10 shown in FIG. 1 is inserted through the through hole 4c. However, the position of the through hole 4c is not limited to the center of the rotor body 4A. The through hole 4c may be located in an area including the central axis of rotation. Furthermore, the shape of the rotor body 4A is not limited to the above. The outer shape of the rotor body 4A in a plan view may be a regular polygon such as a regular hexagon, a regular octagon, or a regular decagon.

[0027] The sliding material 7 is provided on the rotor body 4A. The sliding material 7 has an annular shape in a plan view. The sliding material 7 is provided so as to surround the through-hole 4c of the rotor body 4A. The sliding material 7 is a member that comes into contact with the stator 2 shown in FIG. 1. In this embodiment, specifically, the sliding material 7 comes into contact with the vibrating body 3 of the stator 2. When the ultrasonic motor 1 is driven to rotate the rotor 4, the sliding material 7 of the rotor 4 slides on the surface of the vibrating body 3 of the stator 2.

[0028] The sliding material 7 is made of carbon graphite. Carbon graphite refers to a carbon-based material having a graphitization degree R=D / G of 0.5 or more and 1.2 or less. More specifically, in the Raman spectrum of carbon graphite obtained by Raman spectroscopy, the peak value of the D band is D. In the Raman spectrum, the peak value of the G band is G. The D band is located at 1360 cm in the Raman spectrum. －１ The G band is the band around 1580 cm in the Raman spectrum. －１ The graphitization degree R of the carbon graphite is the value obtained by dividing the peak value D by the peak value G.

[0029] In calculating the degree of graphitization R in this specification, a Raman spectrum of the carbon graphite used in the sliding material is obtained by Raman spectroscopy using an incident laser beam with a wavelength of 532 nm and a grating type of 600 gr / m. Next, the peak values ​​D and G in the obtained Raman spectrum are determined. Next, the obtained peak values ​​D and G are used to calculate R=D / G.

[0030] It is preferable to obtain the peak value D and the peak value G after smoothing the Raman spectrum with a Savizky-Golay-2nd filter.

[0031] If the graphitization degree R of the carbon graphite constituting the sliding material 7 is too high, the lubricity of the sliding material 7 may be reduced. On the other hand, if the graphitization degree R of the carbon graphite constituting the sliding material 7 is too low, the wear resistance of the sliding material 7 may be reduced.

[0032] When obtaining the carbon graphite that constitutes the sliding material 7, for example, carbon powder is solidified by compression molding to obtain a carbon solid. Then, the carbon solid is heat-treated to promote the crystallization of a portion of the carbon solid. In other words, a portion of the carbon solid is converted from carbonaceous to graphite. This results in the carbon graphite. However, the carbon graphite is obtained by promoting the crystallization of a portion of the carbon solid, and is a type of amorphous carbon.

[0033] As shown in FIG. 3 , the rotor body 4A has a rotor base 5 and a leaf spring 6. The outer shape of the rotor body 4A in a plan view is the outer shape of the rotor base 5 in a plan view. The through-hole 4c of the rotor body 4A is provided in the rotor base 5. Meanwhile, the leaf spring 6 has an annular shape in a plan view. The leaf spring 6 is provided so as to surround the through-hole 4c. The rotor base 5 can be made of a suitable metal or a suitable ceramic. The leaf spring 6 can be made of a suitable metal.

[0034] Fig. 4 is a schematic cross-sectional view taken along line II in Fig. 3. The broken lines in Fig. 4 schematically show the displacement of the leaf spring portion, which will be described later.

[0035] The rotor base 5 has a recess 5a. Although not shown, the recess 5a has an annular shape in a plan view. A leaf spring 6 is provided on the rotor base 5 to cover the recess 5a. The leaf spring 6 has a first surface 6a and a second surface 6b. The first surface 6a and the second surface 6b face each other. Of the first surface 6a and the second surface 6b, the first surface 6a is located on the stator 2 side shown in FIG. 1 .

[0036] The sliding material 7 is provided on the leaf spring portion 6 of the rotor body 4A. In this specification, when a member is provided on another member, this includes a case where the other member is provided directly on the member, and a case where the other member is provided indirectly on the member via another layer or the like. In this embodiment, the sliding material 7 is provided directly on the leaf spring portion 6. The sliding material 7 may be bonded to the leaf spring portion 6 by a bonding member such as an adhesive.

[0037] All portions of the sliding material 7 overlap with the recessed portion 5a of the rotor base portion 5 in a plan view. The width of the sliding material 7 is narrower than the width of the leaf spring portion 6 and the width of the recessed portion 5a. The width of the sliding material 7 in this embodiment is the distance between the inner peripheral edge and the outer peripheral edge of the sliding material 7 in a plan view. The same applies to the width of the leaf spring portion 6 and the width of the recessed portion 5a.

[0038] Returning to Figure 3, a feature of this embodiment is that a sliding material 7 is provided on the rotor body 4A of the rotor 4, and the sliding material 7 is made of carbon graphite. This makes it possible to prevent sticking even when the ultrasonic motor 1 using the rotor 4 is used in a high humidity environment. Sticking refers to a phenomenon in which the rotor sticks to the stator, the stator and rotor are fixed to each other, and the ultrasonic motor cannot be started. The above effects are described in detail below.

[0039] When the ultrasonic motor 1 shown in FIG. 1 is driven, the sliding material 7 of the rotor 4 slides on the surface of the vibrator 3 of the stator 2. At this time, even if wear powder is generated from the sliding material 7 made of carbon graphite, no water-soluble components that function as adhesives are generated. Therefore, even in a high-humidity environment where the rotor 4 and stator 2 are exposed to moisture, solidification is unlikely to occur at the contact points between the rotor 4 and stator 2 of the ultrasonic motor 1. This makes it possible to suppress solidification. This allows the ultrasonic motor 1 to be used suitably even in harsh environments with high humidity.

[0040] As shown in Fig. 4, it is preferable that the rotor base 5 has a recess 5a, and that a leaf spring 6 is provided on the rotor base 5 so as to cover the recess 5a. It is also preferable that a sliding member 7 is provided on the leaf spring 6. This allows the rotor 4 to rotate efficiently, as will be explained below.

[0041] In the stator 2 shown in Fig. 1, the vibration of the piezoelectric element 13 serving as a vibration generating element displaces the vibrating body 3, generating a traveling wave. When a traveling wave is generated, portions of the vibrating body 3 undergo large displacement and portions of small displacement. More specifically, when a traveling wave is generated, the displacement is greatest at the crest of the traveling wave in the vibrating body 3. The displacement is also large in portions of the vibrating body 3 surrounding the crest. When the contact area between the rotor 4 and the portion of the vibrating body 3 undergoing large displacement is large, the rotor 4 can be rotated efficiently.

[0042] In this embodiment, as shown in Fig. 4, a sliding member 7 is provided on the leaf spring portion 6. Therefore, the leaf spring portion 6 elastically deforms as shown by the dashed line in Fig. 4 in response to the displacement of the vibrating body 3 due to the traveling wave. This allows the wave crest portion of the vibrating body 3 and its surrounding portion to come into contact with the sliding member 7 when a traveling wave is generated. This makes it possible to increase the area of ​​contact between the largely displaced portion of the vibrating body 3 and the sliding member 7 on the rotor 4. This therefore increases the frictional force between the vibrating body 3 and the rotor 4, allowing the rotor 4 to rotate efficiently.

[0043] The configuration in which the rotor base portion 5 has a recess 5a and the leaf spring portion 6 is provided on the rotor base portion 5 so as to cover the recess 5a can be applied to configurations of the present invention other than this embodiment. However, in the present invention, the rotor main body 4A does not necessarily have to have the leaf spring portion 6. The rotor base portion 5 does not necessarily have to have the recess 5a. The sliding member 7 only needs to be provided on the rotor main body 4A so as to contact the stator 2.

[0044] The configuration of this embodiment will be described in more detail below.

[0045] As shown in Fig. 1, the ultrasonic motor 1 has a first case member 8 and a second case member 9. The second case member 9 is cap-shaped, and the first case member 8 is lid-shaped. The first case member 8 and the second case member 9 form a case. A spring member 16, a rotor 4, and a stator 2 are arranged inside the case.

[0046] The first case member 8 has a first cylindrical protrusion 8 a and a second cylindrical protrusion 8 b. The first cylindrical protrusion 8 a protrudes to the outside of the case. The second cylindrical protrusion 8 b protrudes to the inside of the case. A portion of the second cylindrical protrusion 8 b is located within the through-hole 3 c of the vibrating body 3 of the stator 2.

[0047] A through hole 8c is provided continuously between the first cylindrical protrusion 8a and the second cylindrical protrusion 8b. A first bearing portion 18 is provided in the through hole 8c at a portion where the first cylindrical protrusion 8a is located. A shaft member 10 is inserted through the through hole 8c and the first bearing portion 18. The shaft member 10 protrudes from the through hole 8c of the first case member 8 to the outside of the case. Note that the configuration of the first case member 8 is not limited to the above.

[0048] The second case member 9 has a cylindrical protrusion 9a. The cylindrical protrusion 9a protrudes to the outside of the case. A through hole 9c is provided in the cylindrical protrusion 9a. A second bearing portion 19 is provided in the through hole 9c. The shaft member 10 is inserted through the through hole 9c and the second bearing portion 19. The shaft member 10 protrudes to the outside of the case from the through hole 9c of the second case member 9. Note that the configuration of the second case member 9 is not limited to the above. For example, a plain bearing or a bearing may be used for the first bearing portion 18 and the second bearing portion 19.

[0049] The sliding member 7 of the rotor 4 is in contact with the second main surface 3b of the vibrating body 3 in the stator 2. The second main surface 3b includes a contact surface 3d. The contact surface 3d is the portion of the second main surface 3b that is in contact with the rotor 4. The contact surface 3d is flat. More specifically, the contact surface 3d does not have an uneven structure. The contact surface 3d is configured in the same manner as the portion of the second main surface 3b other than the contact surface 3d. Therefore, when obtaining the stator 2 of this embodiment, it is not necessary to cut the second main surface 3b of the vibrating body 3. This allows for increased productivity of the ultrasonic motor 1.

[0050] An elastic member 12 is provided on the rotor base portion 5 of the rotor 4. More specifically, the elastic member 12 sandwiches the rotor 4 together with the stator 2 in the axial direction Z. The elastic member 12 has an annular shape. Note that the shape of the elastic member 12 is not limited to the above. For example, rubber or resin can be used as the material of the elastic member 12. However, the elastic member 12 does not necessarily have to be provided.

[0051] A spring member 16 is disposed on the second bearing portion 19 side of the elastic member 12. More specifically, the spring member 16 in this embodiment is a metal leaf spring. A through hole 16c is provided in the center of the spring member 16. The shaft member 10 is inserted through the through hole 16c. The shaft member 10 has a wide portion 10a. The width of the wide portion 10a of the shaft member 10 is wider than the width of other portions of the shaft member 10. Note that the width of the shaft member 10 is a dimension along a direction perpendicular to the axial direction Z of the shaft member 10. The inner peripheral edge of the spring member 16 abuts against the wide portion 10a. This makes it possible to suppress misalignment between the spring member 16 and the shaft member 10. However, the material and configuration of the spring member 16 are not limited to those described above. The configuration of the shaft member 10 is also not limited to those described above.

[0052] An elastic force is applied to the rotor 4 from the spring member 16 via the elastic member 12. This presses the rotor 4 against the stator 2. In this case, the frictional force between the stator 2 and the rotor 4 can be increased. This allows the traveling wave to be effectively propagated from the stator 2 to the rotor 4, allowing the rotor 4 to rotate efficiently. This allows the ultrasonic motor 1 to be driven more reliably and efficiently.

[0053] As shown in FIG. 1 , a retaining ring 17 is provided on the shaft member 10. The retaining ring 17 has an annular shape. In a plan view, the retaining ring 17 surrounds the shaft member 10. More specifically, the inner peripheral edge of the retaining ring 17 is located within the shaft member 10. The retaining ring 17 abuts against the first bearing portion 18 from the outside in the axial direction Z. This defines the length between the retaining ring 17 and the wide portion 10a of the shaft member 10, and determines the amount of deflection of the spring member 16. This allows the spring member 16 to apply elastic force to the rotor 4, as described above. The shaft member 10 and the retaining ring 17 can be made of a material such as metal or resin.

[0054] 2, the stator 2 has a plurality of piezoelectric elements 13. A specific configuration of the piezoelectric elements 13 will be described below.

[0055] FIG. 5 is a schematic front cross-sectional view of the piezoelectric element according to the first embodiment.

[0056] The piezoelectric element 13 has a piezoelectric body 14. The piezoelectric body 14 has a third main surface 14a and a fourth main surface 14b. The third main surface 14a and the fourth main surface 14b face each other. The piezoelectric element 13 has a first electrode 15A and a second electrode 15B. The first electrode 15A is provided on the third main surface 14a of the piezoelectric body 14, and the second electrode 15B is provided on the fourth main surface 14b. The shape of the piezoelectric element 13 in a plan view is rectangular. Note that the shape of the piezoelectric element 13 in a plan view is not limited to the above and may be, for example, elliptical.

[0057] In this embodiment, the stator 2 has four piezoelectric elements 13. Note that the number of piezoelectric elements 13 is not limited to the above. It is sufficient that the plurality of piezoelectric elements 13 are dispersed and arranged along the direction of rotation of the traveling wave so as to generate a traveling wave that rotates around an axis parallel to the axial direction Z.

[0058] Alternatively, the stator 2 may have a single piezoelectric element divided into multiple regions. In this case, for example, each region of the piezoelectric element may be polarized in a different direction from each other. The shape of the piezoelectric element in a plan view may be, for example, an annular shape.

[0059] 5 is attached to the first main surface 3a of the vibrating body 3 with an adhesive. The thickness of this adhesive is very thin. Therefore, the first electrode 15A is electrically connected to the vibrating body 3.

[0060] As shown in Figure 4, the rotor base 5 has a groove 5b formed therein so as to connect with the inner peripheral edge of the recess 5a. Similarly, the rotor base 5 has a groove 5c formed therein so as to connect with the outer peripheral edge of the recess 5a. The grooves 5b and 5c each have an annular shape in plan view. A leaf spring 6 is provided from the groove 5b to the groove 5c. More specifically, the inner peripheral edge of the leaf spring 6 is located within the groove 5b. The outer peripheral edge of the leaf spring 6 is located within the groove 5c.

[0061] In this case, when the thickness of the leaf spring portion 6 is set to a desired thickness, the thickness of the portion of the leaf spring portion 6 that protrudes from the rotor base portion 5 in the axial direction Z can be made thinner. Alternatively, if the dimension corresponding to the depth of the groove portions 5b and 5c is equal to or greater than the dimension corresponding to the thickness of the leaf spring portion 6, the leaf spring portion 6 can be configured not to protrude from the rotor base portion 5 in the axial direction Z. This makes it difficult for the leaf spring portion 6 to peel off from the rotor base portion 5.

[0062] In this embodiment, the rotor base 5 having the grooves 5b and 5c is fitted to the leaf spring 6. In this case, it is easy to position the leaf spring 6 when forming the rotor 4. This allows the rotor 4 to be obtained efficiently, effectively improving the productivity of the ultrasonic motor 1. Note that the grooves 5b and 5c do not necessarily have to be provided.

[0063] The ultrasonic motor 1 of this embodiment shown in Figure 1 is just an example, and the configuration of the ultrasonic motor 1 is not limited to the above. Similarly, the configuration of the stator 2 is not limited to the above. The stator 2 only needs to have an appropriate vibrating body 3 and a vibration generating element provided on the vibrating body 3. In the rotor 4 according to the present invention, the sliding member 7 only needs to be provided so as to come into contact with the vibrating body 3 of the stator 2.

[0064] 6 is a schematic plan view of a rotor according to a second embodiment of the present invention, in which a circular orbit A is indicated by a dashed line.

[0065] The rotor 24 of this embodiment differs from the rotor 4 of the first embodiment in that it includes a plurality of sliding members 27. In a plan view, the plurality of sliding members 27 are dispersedly arranged on an annular track A. Except for the above points, the rotor 24 of this embodiment has the same configuration as the rotor 4 of the first embodiment.

[0066] In this embodiment, the annular orbit A is a circular orbit. The annular orbit A corresponds to an orbit along the circulating direction of a traveling wave generated in a stator used in an ultrasonic motor together with the rotor 24. Therefore, the plurality of sliding members 27 are dispersedly arranged along the circulating direction of the traveling wave.

[0067] By distributing the plurality of sliding members 27 in the above-described manner, the rigidity of the rotor 24 in the circumferential direction of the traveling wave can be reduced. As a result, when a traveling wave is generated in a stator used together with the rotor 24, the leaf spring portion 6 can be made to more easily and effectively follow the displacement of the vibrating body of the stator. This allows the sliding members 27 to more reliably come into contact with the wave crest portion and its surrounding portion of the vibrating body when a traveling wave is generated. Therefore, the area of ​​contact between the portion of the vibrating body that undergoes large displacement and the sliding members 27 of the rotor 24 can be increased. Therefore, the frictional force between the vibrating body and the rotor 24 can be increased, allowing the rotor 24 to rotate more reliably and efficiently.

[0068] In addition, the sliding members 27 are made of carbon graphite, which makes it possible to suppress adhesion in this embodiment as in the first embodiment.

[0069] It is preferable that each sliding member 27 is arranged so that the center of gravity of each sliding member 27 is located on the annular orbit A. This allows the ultrasonic motor, when the rotor 24 is used in the ultrasonic motor, to be driven more reliably and stably. Note that it is sufficient that any part of the sliding member 27 is located on the annular orbit A. The center of gravity of the sliding member 27 does not necessarily have to be located on the annular orbit A.

[0070] As in the first embodiment, the width of the sliding material 27 is narrower than the width of the leaf spring portion 6 and the width of the recess 5a in the rotor base portion 5. The width of the sliding material 27 in this embodiment is the dimension of the sliding material 27 along the direction perpendicular to the annular track A in a plan view.

[0071] Fig. 7 is a schematic plan view of a rotor according to a third embodiment, in which protruding portions of a sliding member (to be described later) are indicated by hatching.

[0072] The rotor 34 of this embodiment differs from the rotor 4 of the first embodiment in that the sliding member 37 has a plurality of protrusions 37a. Except for the above, the rotor 34 of this embodiment has the same configuration as the rotor 4 of the first embodiment.

[0073] The sliding member 37 has a circular ring shape in a plan view. The multiple protrusions 37a of the sliding member 37 are distributed and arranged on a circular track. In other words, the multiple protrusions 37a are distributed and arranged along the circumferential direction of a traveling wave generated in a stator used together with the rotor 34 in an ultrasonic motor. The multiple protrusions 37a protrude outward in the axial direction Z from the rotor main body 4A side. Therefore, the multiple protrusions 37a protrude toward the vibrating body side of the stator. The multiple protrusions 37a of the sliding member 37 come into contact with the vibrating body.

[0074] In the sliding material 37, the multiple protruding portions 37a are connected to each other by portions other than the protruding portions 37a. More specifically, the sliding material 37 has multiple protruding portions 37a and multiple non-protruding portions 37b. The thickness of the non-protruding portions 37b is thinner than the thickness of the protruding portions 37a. Adjacent protruding portions 37a are connected to each other by the non-protruding portions 37b. The sliding material 37 is configured such that, in the circumferential direction of a traveling wave generated in a stator used together with the rotor 34, portions that contact the vibrating body of the stator and portions that are thinner than the portions that come into contact with the vibrating body of the stator are alternately provided. This configuration can reduce the rigidity of the rotor 34 in the circumferential direction of the traveling wave.

[0075] This makes it possible to make it easier for the leaf spring portion 6 to effectively follow the displacement of the vibrating body of the stator when a traveling wave is generated in the stator used together with the rotor 34. This allows the wave crest portion of the vibrating body and its surrounding portion to come into more reliable contact with the sliding member 37 when a traveling wave is generated. This makes it possible to increase the area of ​​contact between the portion of the vibrating body that undergoes large displacement and the sliding member 37 of the rotor 34. This makes it possible to increase the frictional force between the vibrating body and the rotor 34, allowing the rotor 34 to rotate more reliably and efficiently.

[0076] The sliding member 37 in this embodiment corresponds to a single member formed by connecting the plurality of sliding members 27 in the second embodiment. Specifically, the portions of the sliding member 37 that correspond to the plurality of sliding members 27 are the plurality of protrusions 37a. Because the sliding member 37 is a single member having the above-described configuration, the sliding member 37 is easy to handle, and the rotor 34 is easy to process and assemble. This increases the productivity of the rotor 34. Furthermore, the strength of the connection between the sliding member 37 and the leaf spring portion 6 of the rotor main body 4A can be increased.

[0077] The thickness of the portion of the sliding member 37 other than the protruding portion 37a, i.e., the thickness of the non-protruding portion 37b, is preferably 70% or less, and more preferably 30% or less, of the thickness of the protruding portion 37a, thereby more reliably reducing the rigidity of the rotor 34 in the circumferential direction of the traveling wave.

[0078] In addition, the sliding material 37 is made of carbon graphite, which makes it possible to suppress adhesion, as in the first embodiment.

[0079] In the sliding member 37, the width of the protruding portion 37a and the width of the non-protruding portion 37b are the same. However, this is not limited to this. For example, in a modification of the third embodiment shown in FIG. 8, in the sliding member 37A, the width of the non-protruding portion 37b is wider than the width of the protruding portion 37a. Because the width of the non-protruding portion 37b is wider, the strength of the connection between the sliding member 37A and the leaf spring portion 6 of the rotor body 4A can be effectively increased.

[0080] The sliding material 37A is made of carbon graphite, which makes it possible to suppress adhesion, as in the third embodiment.

[0081] FIG. 9 is a schematic cross-sectional view showing a portion of a rotor according to a fourth embodiment, which corresponds to the cross section taken along line II in FIG.

[0082] The rotor 44 of this embodiment differs from the rotor 4 of the first embodiment in that the rotor body 44A consists only of a rotor base portion and that the rotor base portion does not have a recess. In other words, the rotor 44 does not have a leaf spring portion. The rotor 44 of this embodiment also differs from the rotor 4 of the first embodiment in that it has a soft resin layer 48. Furthermore, the rotor 44 of this embodiment differs from the rotor 4 of the first embodiment in that the width of the sliding material 7 is the same as the width of the rotor body 44A. Other than the above points, the rotor 44 of this embodiment has the same configuration as the rotor 4 of the first embodiment.

[0083] In this specification, the soft resin layer 48 refers to a resin layer having a relatively low Young's modulus or a relatively low flexural modulus. Specifically, the Young's modulus of the soft resin layer 48 is preferably 80% or less of the Young's modulus of the sliding material 7, or the flexural modulus of the soft resin layer 48 is preferably 80% or less of the flexural modulus of the sliding material 7.

[0084] For example, epoxy resin, phenol resin, polyphenylene sulfide (PPS) resin, or the like can be used for the soft resin layer 48. Alternatively, the soft resin layer 48 may be a resin layer in which an additive is added to an appropriate resin to adjust the Young's modulus to 80% or less of the Young's modulus of the sliding material 7 or the flexural modulus to 80% or less of the flexural modulus of the sliding material 7. Alternatively, the soft resin layer 48 may be a resin layer in which an additive is added to an appropriate resin to adjust at least one of the Young's modulus and the flexural modulus to 7 GPa or less.

[0085] The soft resin layer 48 is provided between the rotor body 44A and the sliding material 7. That is, the rotor 44 has a configuration in which the rotor body 44A, the soft resin layer 48, and the sliding material 7 are laminated in this order.

[0086] More specifically, in this embodiment, all portions of the sliding material 7 are provided on the soft resin layer 48. Note that the sliding material 7 may include portions that are not provided on the soft resin layer 48. The rotor 44 is used in an ultrasonic motor together with a stator having a vibrating body. The portion where the sliding material 7 and the soft resin layer 48 are laminated may overlap, in a plan view, with the wave crest portion and its surrounding portion of the vibrating body when a traveling wave is generated in the stator.

[0087] The soft resin layer 48 and the sliding material 7 may be bonded together by a bonding member such as a separate adhesive. Alternatively, the soft resin layer 48 may be the bonding member that bonds the rotor body 44A and the sliding material 7 together.

[0088] As described above, the width of the sliding member 7 is the same as the width of the rotor body 44A. However, for example, the width of the sliding member 7 may be narrower than the width of the rotor body 44A.

[0089] FIG. 10 is a schematic cross-sectional view showing a state in which the portion of the rotor according to the fourth embodiment shown in FIG. 9 is in contact with the vibrating body of the stator, and a traveling wave is generated in the stator.

[0090] In this embodiment, a portion of the rotor 44 elastically deforms in response to the displacement of the vibrating body 3 due to the traveling wave. More specifically, the soft resin layer 48 elastically deforms. Accordingly, the sliding material 7 also deforms, as shown by the arrows in FIG. 10 . This allows the wave crest portion of the vibrating body 3 and its surrounding portion to come into contact with the sliding material 7 when a traveling wave is generated. Therefore, the area of ​​contact between the largely displaced portion of the vibrating body 3 and the sliding material 7 of the rotor 44 can be increased. Therefore, the frictional force between the vibrating body 3 and the rotor 44 can be increased, allowing the rotor 44 to rotate more reliably and efficiently.

[0091] The soft resin layer 48 elastically deforms in response to the displacement of the vibrating body 3 in the stator, changing the resonant state of the stator. Specifically, part of the vibration energy in the stator is converted into heat as the soft resin layer 48 elastically deforms. In other words, the vibration energy in the stator is absorbed. As a result, the mechanical quality factor Qm of the resonant state of the stator decreases, and the amplitude of the vibrating body 3 in the stator decreases. Note that the greater the amplitude of the vibrating body 3, the higher the maximum rotation speed of the ultrasonic motor. On the other hand, the elastic deformation of the soft resin layer 48 has the effect of widening the frequency range in which the stator resonates. This effect is called the damping effect.

[0092] The damping effect makes it easier for the stator to enter a resonant state even when variations in the stator vibration occur, so that the rotor 44 can be rotated appropriately and the ultrasonic motor can be driven appropriately even when variations in the stator vibration occur.

[0093] Furthermore, by adjusting the Young's modulus or flexural modulus of the soft resin layer 48 through selection of the material of the soft resin layer 48, it is possible to adjust the balance between the magnitude of the vibration amplitude in the vibrating body 3 and the width of the frequency range in which the stator resonates. Alternatively, the above balance can also be adjusted by adjusting the thickness of the soft resin layer 48, etc.

[0094] In addition, the sliding material 7 is made of carbon graphite, which makes it possible to suppress adhesion, as in the first embodiment.

[0095] Incidentally, even when the soft resin layer 48 is provided, the leaf spring portion 6 shown in Fig. 4 may be provided. For example, in a modified example of the fourth embodiment shown in Fig. 11, the rotor base portion 5 of the rotor main body 4A has a recess 5a. The leaf spring portion 6 is provided on the rotor base portion 5 so as to cover the recess 5a. The soft resin layer 48 is provided between the leaf spring portion 6 and the sliding material 7. In other words, the sliding material 7 is indirectly provided on the leaf spring portion 6 via the soft resin layer 48. In other words, the leaf spring portion 6, the soft resin layer 48, and the sliding material 7 are layered in this order.

[0096] In a plan view, the entire sliding member 7 overlaps with the recess 5a of the rotor base 5. The width of the sliding member 7 is narrower than the width of the leaf spring portion 6 and the width of the recess 5a.

[0097] The rotor 54 is used in an ultrasonic motor together with a stator having a vibrating body. The leaf spring portion 6 and the soft resin layer 48 elastically deform in response to the displacement of the vibrating body due to the traveling wave. The sliding material 7 also elastically deforms in response to the elastic deformation of the soft resin layer 48. This allows the wave crest portion of the vibrating body and its surrounding portion to come into more reliable contact with the sliding material 7 when a traveling wave is generated. Therefore, the contact area between the largely displaced portion of the vibrating body and the sliding material 7 of the rotor 54 can be more reliably increased. Therefore, the frictional force between the vibrating body and the rotor 54 can be increased, allowing the rotor 54 to rotate more reliably and efficiently.

[0098] As in the fourth embodiment, even when variations in the vibration of the stator occur due to the damping effect, the rotor 54 can be rotated appropriately, and the ultrasonic motor can be driven appropriately. By adjusting the Young's modulus or flexural modulus of the soft resin layer 48 through selection of the material of the soft resin layer 48, it is possible to adjust the balance between the amplitude of the vibration of the stator vibrating body and the width of the frequency range in which the stator resonates. Alternatively, the above balance can be adjusted by adjusting the thickness of the soft resin layer 48, etc.

[0099] The vibration energy in the stator is also absorbed by the elastic deformation of the leaf springs 6, which follows the displacement of the vibrating body in the stator. The degree of elastic deformation of the leaf springs 6 can be adjusted by selecting the material of the leaf springs 6, adjusting the thickness of the leaf springs 6, or adjusting the width of the recesses 5a in the rotor base 5. This allows the amount of vibration energy absorbed in the stator to be adjusted by the elastic deformation of the leaf springs 6.

[0100] In this modification, the sliding material 7 is also made of carbon graphite, which makes it possible to suppress adhesion, similar to the fourth embodiment.

[0101] The rotor 54 may have a plurality of sliding members 27 in the second embodiment shown in Fig. 6 or sliding member 37 in the third embodiment shown in Fig. 7 instead of the sliding member 7. In these cases, it is possible to reduce the rigidity of the rotor 54 in the circumferential direction of the traveling wave generated in the stator used together with the rotor 54. As a result, as in the second and third embodiments, it is possible to increase the frictional force between the vibrating body of the stator and the rotor 54, and it is possible to rotate the rotor 54 more reliably and efficiently.

[0102] Similarly, the rotor 44 of the fourth embodiment may have the plurality of sliding members 27 of the second embodiment shown in Fig. 6 or the sliding member 37 of the third embodiment shown in Fig. 7 instead of the sliding member 7. In these cases, it is possible to reduce the rigidity of the rotor 44 in the circumferential direction of the traveling wave generated in the stator used together with the rotor 44. This makes it possible to increase the frictional force between the vibrating body of the stator and the rotor 44, as in the second and third embodiments, and to rotate the rotor 44 more reliably and efficiently.

[0103] FIG. 12 is a schematic bottom view of a stator according to a fifth embodiment of the present invention.

[0104] The stator 62 of this embodiment differs from the stator 2 of the first embodiment in that it includes a sliding member 7. In all other respects, the stator 62 of this embodiment has the same configuration as the stator 2 of the first embodiment.

[0105] A sliding material 7 is provided on the second main surface 3b of the vibrating body 3 in the stator 62. The sliding material 7 has a configuration similar to that of the sliding material 7 of the rotor 4 in the first embodiment. Specifically, the sliding material 7 in this embodiment has an annular shape in a plan view. The sliding material 7 is made of carbon graphite.

[0106] The sliding member 7 is provided in the stator 62 so as to surround the through-hole 3c of the vibrator 3. The stator 62 is used together with a rotor in an ultrasonic motor. The sliding member 7 in the stator 62 is a member that comes into contact with the rotor. When the ultrasonic motor is driven, the surface of the rotor slides on the sliding member 7. Therefore, when the ultrasonic motor is driven, the sliding member 7 in the stator 62 slides on the surface of the rotor relatively.

[0107] There are no particular limitations on the configuration of the rotor used together with the stator 62. It is sufficient that the material of the portion of the rotor that comes into contact with the sliding member 7 does not contain resin.

[0108] When an ultrasonic motor using the stator 62 of this embodiment is driven, even if wear powder is generated from the sliding material 7 made of carbon graphite, no water-soluble components that function as adhesives are generated. Therefore, even in a high-humidity environment where the rotor and stator 62 are exposed to moisture, solidification is unlikely to occur at the contact points between the rotor and stator 62 in the ultrasonic motor. This makes it possible to suppress solidification. This allows the ultrasonic motor to be used effectively even in harsh, high-humidity environments.

[0109] The stator 62 may have, instead of the sliding member 7, for example, the plurality of sliding members 27 in the second embodiment shown in Fig. 6 or the sliding member 37 in the third embodiment shown in Fig. 7. Alternatively, the stator 62 may have, instead of the sliding member 7, for example, the sliding member 37A in the modified example of the third embodiment shown in Fig. 8.

[0110] Fig. 13 is a schematic bottom view of a stator according to a sixth embodiment. Fig. 14 is a schematic cross-sectional view taken along line II-II in Fig. 13. Piezoelectric elements are omitted in Figs. 13 and 14.

[0111] 13 and 14 , this embodiment differs from the fifth embodiment in that a plurality of protrusions 73e are provided on the second main surface 73b of the vibrating body 73. This embodiment also differs from the fifth embodiment in that a plurality of sliding members 27 are provided. Except for the above points, the stator 72 of this embodiment has the same configuration as the stator 62 of the fifth embodiment. Therefore, the vibrating body 73 has a first main surface 73a and a second main surface 73b, and the vibrating body 73 is provided with a through hole 73c.

[0112] As described above, the piezoelectric elements are omitted in Figures 13 and 14. However, in this embodiment, similar to the fifth embodiment, a plurality of piezoelectric elements are provided on the first main surface 73a of the vibrating body 73.

[0113] A plurality of protrusions 73e are provided on the second main surface 73b of the vibrating body 73 so as to surround the through-hole 73c. ​​The plurality of protrusions 73e are distributed and arranged on an annular track. Specifically, the annular track is a circular track. In other words, the plurality of protrusions 73e are distributed and arranged along the circumferential direction of a traveling wave generated in the stator 72.

[0114] The multiple protrusions 73e protrude outward in the axial direction Z from the second main surface 73b of the vibrating body 73. When the stator 72 is used together with a rotor in an ultrasonic motor, the multiple protrusions 73e protrude toward the rotor side.

[0115] One sliding member 27 is provided on each of the plurality of protrusions 73 e. Thus, like the plurality of protrusions 73 e, the plurality of sliding members 27 are dispersed and arranged along the circumferential direction of the traveling wave generated in the stator 72. The plurality of sliding members 27 come into contact with the rotor.

[0116] The plurality of sliding members 27 are made of carbon graphite, which makes it possible to suppress adhesion in this embodiment as in the fifth embodiment.

[0117] Additionally, in this embodiment, the multiple protrusions 73e protrude outward in the axial direction Z from the second main surface 73b. As a result, when a traveling wave is generated in the vibrating body 73 of the stator 72, the tips of the multiple protrusions 73e are displaced even more greatly. The rotor then comes into contact with the sliding members 27 provided on the surfaces of the tips of the protrusions 73e on the second main surface 73b. Therefore, the traveling wave generated in the stator 72 can efficiently rotate the rotor.

[0118] Specifically, the displacement of the traveling wave generated in the stator 72 is a displacement caused by the flexural deformation of the vibrating body 73. This displacement caused by the flexural deformation is a displacement parallel to the axial direction Z. Therefore, when a traveling wave is generated, flexural deformation occurs on the first main surface 73a and the second main surface 73b of the vibrating body 73. As described above, the tip ends of the multiple protrusions 73e provided on the second main surface 73b are displaced even more greatly.

[0119] However, deflection is unlikely to occur on the surface of the tip of each protrusion 73e where each sliding member 27 is provided. Therefore, deflection is unlikely to occur in the plurality of sliding members 27. This reduces the energy loss of the stator 72 that accompanies deflection of the plurality of sliding members 27. This allows the ultrasonic motor to be driven efficiently.

[0120] In addition, there is a concern that cracks may occur due to excessive bending deformation in each of the slide members 27 made of carbon graphite. In contrast, in this embodiment, bending deformation is unlikely to occur in each of the slide members 27. Therefore, cracks in each of the slide members 27 can be more reliably suppressed.

[0121] The ultrasonic motor according to the present invention may include, for example, the rotor according to the present invention and a suitable stator. Alternatively, the ultrasonic motor according to the present invention may include a suitable rotor and the stator according to the present invention. These features make it possible to suppress adhesion.

[0122] Examples of the configuration of the rotor, stator, and ultrasonic motor according to the present invention will be described below.

[0123] <1> A rotor used in an ultrasonic motor having a stator with a vibrating body and a vibration generating element provided on the vibrating body, the rotor comprising: a rotor body; and a sliding material provided on the rotor body and in contact with the vibrating body, the sliding material being made of carbon graphite.

[0124] <2> The rotor according to <1>, wherein, in a Raman spectrum of the carbon graphite used in the sliding material obtained by Raman spectroscopy with an incident laser light wavelength of 532 nm and a grating type of 600 gr / m, when a peak value of a D band is D, a peak value of a G band is G, and a graphitization degree of the carbon graphite is R, R = D / G, and the graphitization degree R of the carbon graphite is 0.5 or more and 1.2 or less.

[0125] <3> A rotor according to <1> or <2>, wherein the rotor body has a rotor base portion having a recess and a leaf spring portion provided on the rotor base portion so as to cover the recess, and the sliding material is provided on the leaf spring portion.

[0126] <4> The rotor according to <3>, further comprising a soft resin layer provided between the leaf spring portion and the sliding material.

[0127] <5> The rotor according to <1> or <2>, further comprising a soft resin layer provided between the rotor body and the sliding material.

[0128] <6> The rotor according to any one of <1> to <5>, comprising a plurality of the sliding members, the plurality of sliding members being dispersed and arranged on an annular track in a plan view.

[0129] <7> The rotor according to any one of <1> to <5>, wherein the sliding member includes a plurality of protrusions that are dispersedly arranged on a circular track in a plan view, and the plurality of protrusions protrude toward the vibrating body.

[0130] <8> A stator used in an ultrasonic motor having a rotor, the stator comprising: a vibrating body; a vibration generating element provided on the vibrating body; and a sliding material provided on the vibrating body and in contact with the rotor, the sliding material being made of carbon graphite.

[0131] <9> The stator according to <8>, wherein, in a Raman spectrum of the carbon graphite used in the sliding material obtained by Raman spectroscopy with an incident laser light wavelength of 532 nm and a grating type of 600 gr / m, when a peak value of a D band is D, a peak value of a G band is G, and a graphitization degree of the carbon graphite is R, R = D / G, and the graphitization degree R of the carbon graphite is 0.5 or more and 1.2 or less.

[0132] <10> An ultrasonic motor comprising: the rotor according to any one of <1> to <7>; the vibrating body; and the stator having the vibration generating element provided on the vibrating body.

[0133] <11> An ultrasonic motor comprising the stator according to <8> or <9> and the rotor.

[0134] DESCRIPTION OF SYMBOLS 1...Ultrasonic motor 2...Stator 3...Vibrator 3a, 3b...First and second main surfaces 3c...Through hole 3d...Contact surface 4...Rotor 4A...Rotor body 4c...Through hole 5...Rotor base portion 5a...Recess 5b, 5c...Groove portion 6...Leaf spring portion 6a, 6b...First and second surfaces 7...Sliding material 8...First case member 8a, 8b...First and second cylindrical protrusions 8c...Through hole 9...Second case member 9a...Cylindrical protrusion 9c...Through hole 10...Shaft member 10a...Wide portion 12...Elastic member 13...Piezoelectric element 14...Piezoelectric body 14a, 14b...Third and fourth main surfaces 15A, 15B...First and second electrodes 16...Spring member 16c...Through hole 17...Retaining ring DESCRIPTION OF SYMBOLS 18, 19...First and second bearing portions 24...Rotor 27...Sliding member 34...Rotor 37, 37A...Sliding member 37a...Protruding portion 37b...Non-protruding portion 44...Rotor 44A...Rotor body 48...Soft resin layer 54...Rotor 62, 72...Stator 73...Vibrating body 73a, 73b...First and second main surfaces 73c...Through hole 73e...Protruding portion

Claims

1. A rotor used in an ultrasonic motor equipped with a stator having a vibrating body and a vibration generating element provided on the vibrating body, the rotor comprising: a rotor body; and a sliding material provided on the rotor body and in contact with the vibrating body, wherein the sliding material is made of carbon graphite.

2. The rotor according to claim 1, wherein, in a Raman spectrum of the carbon graphite used in the sliding material obtained by Raman spectroscopy with an incident laser light wavelength of 532 nm and a grating type of 600 gr / m, when the peak value of the D band is D, the peak value of the G band is G, and the graphitization degree of the carbon graphite is R, R = D / G, and the graphitization degree R of the carbon graphite is 0.5 or more and 1.2 or less.

3. A rotor according to claim 1 or 2, wherein the rotor body has a rotor base portion having a recess, and a leaf spring portion provided on the rotor base portion so as to cover the recess, and the sliding material is provided on the leaf spring portion.

4. The rotor according to claim 3, further comprising a soft resin layer provided between said leaf spring portion and said sliding member.

5. The rotor according to claim 1 or 2, further comprising a soft resin layer provided between said rotor body and said sliding member.

6. A rotor according to any one of claims 1 to 5, comprising a plurality of said sliding members, said plurality of sliding members being dispersedly arranged on an annular track in a plan view.

7. A rotor according to any one of claims 1 to 5, wherein the sliding member includes, in a plan view, a plurality of protrusions dispersedly arranged on a circular track, the plurality of protrusions protruding toward the vibrating body.

8. A stator used in an ultrasonic motor having a rotor, comprising: a vibrating body; a vibration generating element provided on the vibrating body; and a sliding material provided on the vibrating body and in contact with the rotor, wherein the sliding material is made of carbon graphite.

9. A stator according to claim 8, wherein, in a Raman spectrum of the carbon graphite used in the sliding material obtained by Raman spectroscopy with an incident laser light wavelength of 532 nm and a grating type of 600 gr / m, when the peak value of the D band is D, the peak value of the G band is G, and the graphitization degree of the carbon graphite is R, R = D / G, and the graphitization degree R of the carbon graphite is 0.5 or more and 1.2 or less.

10. An ultrasonic motor comprising: a rotor according to any one of claims 1 to 7; and a stator having the vibrating body and the vibration generating element provided on the vibrating body.

11. An ultrasonic motor comprising: a stator according to claim 8 or 9; and the rotor.

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