Ultrasonic motor

Abstract

Provided is an ultrasonic motor capable of improving vibration efficiency of a vibrating body and capable of improving rotation efficiency. The ultrasonic motor of the present invention includes a stator (6) having a vibrating body (12) and first to fourth piezoelectric elements (13A to 13D), a rotor, and a wiring member (7) having an insulating base material (16) and first and second wirings (17A, 17B). The plurality of piezoelectric elements are dispersedly arranged along a circumferential direction of a traveling wave that circulates around a center in an axial direction, so that the traveling wave is generated by vibrating the vibrating body (12). The first and third piezoelectric elements (13A, 13C) are opposed across the center of the traveling wave. The first wiring (17A) is electrically connected to the first and third piezoelectric elements (13A, 13C), and the second wiring (17B) is electrically connected to the second and fourth piezoelectric elements (13B, 13D). The second wiring (17B) extends from the second piezoelectric element (13B) side, over the third piezoelectric element (13C), and toward the fourth piezoelectric element (13D) side.

Description

Technical Field

[0001] This invention relates to an ultrasonic motor having multiple piezoelectric elements. Background Technology

[0002] Previously, various ultrasonic motors that vibrate the stator using piezoelectric elements have been proposed. For example, in the vibration wave motor described in Patent Document 1 below, multiple piezoelectric elements are attached to an elastomer. A flexible printed circuit board (FPC) is used to transmit signals to the multiple piezoelectric elements. The FPC is multilayered. Therefore, two-phase signals can be transmitted.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-142473 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, when using multi-layer FPCs, vibration energy is easily absorbed, and vibration efficiency may deteriorate. Consequently, the rotational efficiency of the motor also deteriorates. On the other hand, when using a single-layer FPC to transmit signals to multiple piezoelectric elements and transmit two-phase signals, the possibility of short circuits increases, and the wiring may also become more complex.

[0008] The purpose of this invention is to provide an ultrasonic motor that can improve the vibration efficiency and rotation efficiency of a vibrating body.

[0009] Solution for solving the problem

[0010] The ultrasonic motor of the present invention comprises: a stator having a plate-shaped vibrating body and a plurality of piezoelectric elements, the plate-shaped vibrating body including a first main surface and a second main surface opposite to each other, the plurality of piezoelectric elements being disposed on the first main surface of the vibrating body; a rotor having direct or indirect contact with the second main surface of the vibrating body; and a wiring member having an insulating substrate and a first wiring and a second wiring, the insulating substrate being disposed on the first main surface of the vibrating body, the first wiring and the second wiring being disposed on the insulating substrate, wherein when the direction connecting the first main surface and the second main surface of the vibrating body and along the rotation center is defined as the axial direction, the plurality of piezoelectric elements are dispersed along the circumferential direction of a traveling wave centered on the axial direction. The configuration is such that the traveling wave is generated by vibrating the vibrator. The plurality of piezoelectric elements include a first piezoelectric element, a second piezoelectric element, a third piezoelectric element, and a fourth piezoelectric element. When viewed from the axial direction, the first and third piezoelectric elements are opposite each other across the center of the traveling wave, and the second and fourth piezoelectric elements are opposite each other across the center of the traveling wave. The first wiring of the wiring member is electrically connected to the first and third piezoelectric elements, and the second wiring is electrically connected to the second and fourth piezoelectric elements. When viewed from the axial direction, the second wiring extends from the side of the second piezoelectric element, through the third piezoelectric element, and toward the side of the fourth piezoelectric element.

[0011] Invention Effects

[0012] The ultrasonic motor according to the present invention can improve the vibration efficiency of the vibrating body and improve the rotation efficiency. Attached Figure Description

[0013] Figure 1 This is a perspective view of the ultrasonic motor according to the first embodiment of the present invention.

[0014] Figure 2 This is an exploded perspective view of the ultrasonic motor according to the first embodiment of the present invention.

[0015] Figure 3 This is a bottom view of the stator in the first embodiment of the present invention.

[0016] Figure 4 This is a perspective view of the stator and wiring components in the first embodiment of the present invention.

[0017] Figure 5 This is a perspective view showing the stator and wiring components of the first embodiment of the present invention, omitting the insulating cover.

[0018] Figure 6This is a top view showing the third piezoelectric element and the portion connected to the first wiring in the first embodiment of the present invention, with the insulating cover omitted.

[0019] Figure 7 This is a perspective view showing the third piezoelectric element and the portion connected to the first wiring in the first embodiment of the present invention, with the insulating cover omitted.

[0020] Figure 8 This is a top view showing the third piezoelectric element and the vicinity of the portion connected to the first wiring in the first embodiment of the present invention.

[0021] Figure 9 This is a front cross-sectional view of the third piezoelectric element in the first embodiment of the present invention.

[0022] Figure 10 This is a circuit diagram illustrating the circuit for applying a drive signal to a piezoelectric element in the first embodiment of the present invention.

[0023] Figure 11 (a) to (c) are schematic bottom views illustrating the stator of the excited traveling wave in the first embodiment of the present invention.

[0024] Figure 12 This is a top view showing the third piezoelectric element in a first variation of the first embodiment, with the insulating cover omitted.

[0025] Figure 13 This is a schematic cross-sectional view showing the vicinity of the third piezoelectric element in a second variation of the first embodiment. Detailed Implementation

[0026] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings, thereby making the present invention clear.

[0027] It should be noted that the embodiments described in this specification are illustrative, and it is indicated in advance that partial substitutions or combinations of structures can be made between different embodiments.

[0028] Figure 1 This is a perspective view of the ultrasonic motor according to the first embodiment of the present invention. Figure 2 This is an exploded perspective view of the ultrasonic motor according to the first embodiment.

[0029] like Figure 1 As shown, the ultrasonic motor 1 has a first housing member 2A and a second housing member 2B. The second housing member 2B is fixed to the first housing member 2A. Thus, the housing 2 is formed. Figure 2As shown, a bearing 3, a rotor 4, a friction element 5, a stator 6, and a pressure spring 8 are arranged inside the housing 2. The stator 6 has a vibrating body 12. In the ultrasonic motor 1, a vibration is generated by vibrating the vibrating body 12 of the stator 6. Figure 2 The traveling wave shown is centered on axis Z and rotates around it. This traveling wave causes rotor 4 to rotate.

[0030] Here, the vibrating body 12 of the stator 6 has a first principal surface 12a and a second principal surface 12b. The first principal surface 12a and the second principal surface 12b are opposite to each other. In this specification, the axial direction Z refers to the direction connecting the first principal surface 12a and the second principal surface 12b, and is along the direction of the center of rotation.

[0031] Figure 3 This is a bottom view of the stator in the first embodiment.

[0032] The stator 6 has multiple piezoelectric elements. In this embodiment, the multiple piezoelectric elements are a first piezoelectric element 13A, a second piezoelectric element 13B, a third piezoelectric element 13C, and a fourth piezoelectric element 13D. The multiple piezoelectric elements are disposed on the first main surface 12a of the vibrator 12. More specifically, the multiple piezoelectric elements are attached to the vibrator 12 using an adhesive. For example, epoxy resin, polyethylene resin, etc., can be used as the adhesive.

[0033] Multiple piezoelectric elements are distributed along the direction of a traveling wave that revolves around the Z-axis, thereby generating the traveling wave. When viewed from the Z-axis, the first piezoelectric element 13A and the third piezoelectric element 13C are positioned opposite each other across the center of the traveling wave. The second piezoelectric element 13B and the fourth piezoelectric element 13D are positioned opposite each other across the center of the traveling wave.

[0034] In this embodiment, the center of the traveling wave coincides with the center of the stator 6 and the center of the vibrator 12. However, the center of the traveling wave does not necessarily have to coincide with the center of the stator 6 and the center of the vibrator 12.

[0035] like Figure 3 As shown, when viewed from the Z-axis, the third piezoelectric element 13C is rectangular and has a first side 13a, a second side 13b, a third side 13c, and a fourth side 13d, which are the outer periphery of the third piezoelectric element 13C. The first side 13a and the third side 13c are opposite each other. The second side 13b and the fourth side 13d are opposite each other. Here, in this specification, unless otherwise specified, when viewed from the Z-axis, the side farther from the axis is called the outer side, and the side closer to the axis is called the inner side. The first side 13a is located inside the third side 13c. The second side 13b and the fourth side 13d extend from the inner side to the outer side. The first piezoelectric element 13A, the second piezoelectric element 13B, and the fourth piezoelectric element 13D also have the first to fourth sides in the same way as the third piezoelectric element 13C.

[0036] Multiple piezoelectric elements are electrically connected to the wiring component. The wiring component and... Figure 1 The connector 9 shown is electrically connected. Multiple piezoelectric elements are electrically connected to the outside via wiring components and connector 9.

[0037] Hereinafter, the features of this embodiment will be described together with the details of the wiring component 7 in this embodiment.

[0038] Figure 4 This is a perspective view of the stator and wiring components in the first embodiment. Figure 5 This is a perspective view showing the stator and wiring components of the first embodiment, omitting the insulating cover. It should be noted that the insulating cover will be described later.

[0039] like Figure 4 and Figure 5 As shown, the wiring member 7 has an insulating substrate 16 disposed on a first main surface 12a of the vibrator 12. The insulating substrate 16 has a first substrate main surface 16a and a second substrate main surface 16b. The first substrate main surface 16a and the second substrate main surface 16b are opposite to each other. The second substrate main surface 16b is the surface on the vibrator 12 side. A first wiring 17A and a second wiring 17B are disposed on the first substrate main surface 16a of the insulating substrate 16. Thus, the insulating substrate 16 is disposed between the first wiring 17A and the second wiring 17B and the vibrator 12. Therefore, the first wiring 17A and the second wiring 17B are electrically insulated from the vibrator 12.

[0040] In addition, such as Figure 5 As shown, the wiring component 7 has a grounding wiring 17C. The grounding wiring 17C has a portion disposed on a first substrate main surface 16a of the insulating substrate 16 and a portion disposed on a first main surface 12a of the vibrator 12. It should be noted that in this embodiment, the vibrator 12 is made of metal. The grounding wiring 17C is electrically connected to the vibrator 12. More specifically, the grounding wiring 17C is connected to the vibrator 12 at a portion located inside the first wiring 17A. The grounding wiring 17C is electrically connected to the ground potential via the vibrator 12. It should be noted that the position of the grounding wiring 17C is not limited to the above. The first wiring 17A, the second wiring 17B, and the grounding wiring 17C are connected to the connector 9 described above.

[0041] like Figure 4 As shown, the wiring component 7 has an insulating cover 18 that covers the first wiring 17A, the second wiring 17B, the grounding wiring 17C, and the first substrate main surface 16a of the insulating substrate 16. It should be noted that the insulating cover 18 only needs to cover the first wiring 17A and the second wiring 17B. The insulating cover 18 can also extend to multiple piezoelectric elements or the vibrator 12.

[0042] For the first wiring 17A, the second wiring 17B, and the grounding wiring 17C, copper foil, for example, can be used. However, the materials for the first wiring 17A, the second wiring 17B, and the grounding wiring 17C are not limited to the above, and suitable metals can be used. For the insulating substrate 16 and the insulating cover 18, polyimide, for example, can be used. However, the materials for the insulating substrate 16 and the insulating cover 18 are not limited to the above, and suitable insulating materials can be used.

[0043] Figure 6 This is a top view showing the third piezoelectric element in the first embodiment and the portion connected to the first wiring, with the insulating cover omitted. Figure 7 This is a perspective view showing the third piezoelectric element in the first embodiment and the portion connected to the first wiring, with the insulating cover omitted. It should be noted that... Figure 6 In the image, the insulating substrate 16 is shown by a shaded line.

[0044] like Figure 5 and Figure 6 As shown, the first wiring 17A of the wiring component 7 is electrically connected to the first piezoelectric element 13A and the third piezoelectric element 13C. More specifically, as... Figure 5 As shown, the portion of the first wiring 17A connected to the first piezoelectric element 13A is not disposed on the insulating substrate 16 of the wiring member 7. Similarly, as Figure 6 As shown, the portion of the first wiring 17A that connects to the third piezoelectric element 13C is not located on the insulating substrate 16 of the wiring member 7. More specifically, as... Figure 7 As shown, the insulating substrate 16 has an opening 16c. When viewed from the Z-axis, the opening 16c is located on the third piezoelectric element 13C. The portion of the first wiring 17A connected to the third piezoelectric element 13C is located within the opening 16c. On the other hand, the first wiring 17A is not electrically connected to the second piezoelectric element 13B and the fourth piezoelectric element 13D.

[0045] return Figure 6 The second wiring 17B is electrically connected to the second piezoelectric element 13B and the fourth piezoelectric element 13D. More specifically, the portions of the second wiring 17B connected to the second piezoelectric element 13B and the portions connected to the fourth piezoelectric element 13D are not provided on the insulating substrate 16 of the wiring member 7. On the other hand, the second wiring 17B is not electrically connected to the first piezoelectric element 13A and the third piezoelectric element 13C.

[0046] When viewed from the Z-axis, the second wiring 17B extends from the side of the second piezoelectric element 13B, through the third piezoelectric element 13C, and toward the side of the fourth piezoelectric element 13D. It should be noted that an insulating substrate 16 is disposed between the second wiring 17B and the third piezoelectric element 13C.

[0047] The first wiring 17A is bonded to the first piezoelectric element 13A and the third piezoelectric element 13C using an adhesive. Similarly, the second wiring 17B is bonded to the second piezoelectric element 13B and the fourth piezoelectric element 13D using an adhesive. For example, epoxy resin, polyethylene resin, etc., can be used as the adhesive. However, the adhesive material is not limited to the above. The bonding method between the first wiring 17A and the second wiring 17B and each piezoelectric element is not limited to the above; for example, bonding can also be performed using solder or the like.

[0048] like Figure 5 As shown, in this embodiment, the portion of the first wiring 17A connected to the first piezoelectric element 13A has a first comb-shaped portion 17a. Similarly, the portion of the second wiring 17B connected to the second piezoelectric element 13B has a second comb-shaped portion 17b. The portion of the first wiring 17A connected to the third piezoelectric element 13C has a third comb-shaped portion 17c. The portion of the second wiring 17B connected to the fourth piezoelectric element 13D has a fourth comb-shaped portion 17d. When viewed from the Z-axis, the first comb-shaped portion 17a, the second comb-shaped portion 17b, and the fourth comb-shaped portion 17d are comb-shaped portions facing outwards. On the other hand, when viewed from the Z-axis, the third comb-shaped portion 17c is a comb-shaped portion facing inwards. It should be noted that the first comb-shaped portion 17a, the second comb-shaped portion 17b, the third comb-shaped portion 17c, and the fourth comb-shaped portion 17d can face inwards or outwards when viewed from the Z-axis. The first wiring 17A and the second wiring 17B may not necessarily have the aforementioned comb-shaped portions.

[0049] The feature of this embodiment is that, when viewed from the Z-axis, the second wiring 17B extends from the side of the second piezoelectric element 13B, through the third piezoelectric element 13C, and toward the side of the fourth piezoelectric element 13D. Therefore, the wiring can be routed using the wiring member 7, which is a single layer. This improves the vibration efficiency of the vibrator 12 and the rotational efficiency of the ultrasonic motor 1. Furthermore, since it is not necessary to make the wiring member 7 multi-layered, productivity can be improved.

[0050] like Figure 6 and Figure 7As shown, preferably, the insulating substrate 16 has an opening 16c, which, when viewed from the Z-axis, includes a portion of the outer periphery of the third piezoelectric element 13C. More specifically, for example, as in this embodiment, the opening 16c preferably includes a first side 13a that is part of the outer periphery of the third piezoelectric element 13C. In this case, the area of ​​the inner portion of the opening 16c when viewed from the Z-axis can be effectively increased. Therefore, without increasing the routing of the second wiring 17B, excess adhesive can be easily and effectively discharged from between the first wiring 17A and the third piezoelectric element 13C to the outside of the piezoelectric element surface. Therefore, the formation of adhesive clumps between the first wiring 17A and the third piezoelectric element 13C can be suppressed. Furthermore, the adhesive between the first wiring 17A and the third piezoelectric element 13C can be prevented from becoming too thick, thus making it difficult for air bubbles to form in the adhesive between the first wiring 17A and the third piezoelectric element 13C. Therefore, it is difficult for stress to concentrate on the adhesive due to temperature changes, thus effectively preventing the first wiring 17A from breaking. This improves reliability against thermal shock.

[0051] As in this embodiment, the first wiring 17A preferably has a first comb-shaped portion 17a and a third comb-shaped portion 17c. Therefore, even at the junction of the first wiring 17A with the first piezoelectric element 13A and the third piezoelectric element 13C, the first piezoelectric element 13A and the third piezoelectric element 13C can be easily joined to the insulating cover 18. Similarly, the second wiring 17B preferably has a second comb-shaped portion 17b and a fourth comb-shaped portion 17d. Therefore, even at the junction of the second wiring 17B with the second piezoelectric element 13B and the fourth piezoelectric element 13D, the second piezoelectric element 13B and the fourth piezoelectric element 13D can be easily joined to the insulating cover 18.

[0052] The third comb-shaped portion 17c of the first wiring 17A is preferably a comb-shaped portion facing inward. In other words, the third comb-shaped portion 17c of the first wiring 17A is preferably a comb-shaped portion facing the outer periphery, i.e., the first side 13a, of the third piezoelectric element 13C. In this case, when excess adhesive is discharged from between the first wiring 17A and the third piezoelectric element 13C to the outside of the piezoelectric element surface, the adhesive is easily discharged towards the inward side when viewed from the Z-axis. Thus, even if the distance between the portion of the second wiring 17B located on the outer side of the first wiring 17A and the third comb-shaped portion 17c of the first wiring 17A is short, the aforementioned discharge of adhesive to the outside of the piezoelectric element surface can be easily performed. Therefore, without increasing the routing of the second wiring 17B, it is even easier to discharge adhesive from between the first wiring 17A and the third piezoelectric element 13C to the outside of the piezoelectric element surface.

[0053] Figure 8 This is a top view showing the third piezoelectric element in the first embodiment and the area near the portion connected to the first wiring.

[0054] The insulating cover 18 has a cutout 18a. When viewed from the Z-axis, the cutout 18a is located inside the opening 16c. The cutout 18a surrounds the portion of the first wiring 17A that connects to the third piezoelectric element 13C. The cutout 18a on the third piezoelectric element 13C is located between the portion of the insulating cover 18 covering the first wiring 17A and the portion covering the second wiring 17B. Therefore, even if there is a height difference between the surfaces of the first wiring 17A and the second wiring 17B on the insulating cover 18 side, both the first wiring 17A and the second wiring 17B can be more reliably pressed against the insulating cover 18. However, the insulating cover 18 may also not have the cutout 18a.

[0055] The first wiring 17A preferably extends through the insulating substrate 16 to the portion of the third piezoelectric element 13C and reaches the third piezoelectric element 13C. In this case, the first wiring 17A can be more reliably electrically insulated from the vibrator 12 and electrically connected to the third piezoelectric element 13C. Similarly, as Figure 5 As shown, the first wiring 17A preferably extends through the insulating substrate 16 to a portion of the first piezoelectric element 13A and reaches the first piezoelectric element 13A. For example... Figure 6 As shown, the second wiring 17B preferably extends through the insulating substrate 16 to a portion of the second piezoelectric element 13B and to the second piezoelectric element 13B. Furthermore, the second wiring 17B preferably extends through the insulating substrate 16 to a portion of the fourth piezoelectric element 13D and to the fourth piezoelectric element 13D.

[0056] In this embodiment, the multiple piezoelectric elements are four piezoelectric elements. It should be noted that this is not a limitation; the multiple piezoelectric elements can be 4x piezoelectric elements. It should be noted that x is a positive number greater than or equal to 1. When the number of piezoelectric elements is more than four, the insulating substrate 16 preferably has two or more openings 16c.

[0057] However, in the wiring component 7, for example, a driving wiring pattern may be provided on the first substrate main surface 16a of the insulating substrate 16, and a detection pattern may be provided on the second substrate main surface 16b. The detection pattern refers to the wiring pattern that constitutes the circuit for detecting the vibration of the piezoelectric element. In this way, two layers of wiring patterns can also be used in the wiring component 7.

[0058] The following describes the details of the other structures of the ultrasonic motor 1.

[0059] like Figure 2As shown, the rotor 4 has a circular plate-shaped rotor body 4a and a rotating shaft 4b connected to the rotor body 4a at one end. When the rotor 4 rotates, the rotating shaft 4b rotates accordingly. It should be noted that the shape of the rotor body 4a is not limited to the above description. When viewed from the Z-axis, the shape of the rotor body 4a can also be, for example, a regular hexagon, a regular octagon, or a regular decagon, etc., a regular polygon.

[0060] exist Figure 2 In this embodiment, the friction element 5 is fixed to the lower surface of the rotor body 4a of the rotor 4, and is provided to increase the friction between the rotor 4 and the vibrator 12. It should be noted that in this embodiment, the rotor 4 indirectly contacts the second main surface 12b of the vibrator 12 through the friction element 5, but the friction element 5 may not be necessary. In this case, the rotor 4 may also directly contact the second main surface 12b of the vibrator 12.

[0061] A cross-shaped recess 2a is provided on the upper surface of the first housing member 2A. A pressure spring 8, serving as a pressure member, is disposed between the first main surface 12a of the vibrating body 12 and the first housing member 2A. The pressure spring 8 has a cross-shaped shape when viewed from above, and the front end of the cross-shaped portion fits into the cross-shaped portion of the recess 2a. Thus, the pressure spring 8 is configured not to rotate relative to the axial center, and the center of the shaft coincides with the center of the spring.

[0062] The pressure spring 8 provides pressure for pressing the vibrator 12 against the rotor 4. To provide this pressure, the first housing member 2A and the second housing member 2B are fixed together, and the pressure is provided by the elastic force of the pressure spring 8.

[0063] It should be noted that the first housing member 2A and the second housing member 2B can be fixed by means of suitable fixing structures, such as bolts and nuts passing through the through holes 2b and 2c.

[0064] A cylindrical protrusion 2e with a through hole 2d is provided in the center of the second housing member 2B. The bearing 3 is housed in the through hole 2d, and the rotating shaft 4b passes through the through hole of the bearing 3.

[0065] like Figure 2 As shown, the vibrating body 12 of the stator 6 is in the shape of a circular plate. A through hole 12d is provided in the center of the vibrating body 12. It should be noted that the shape of the vibrating body 12 when viewed from the Z-axis is not limited to a circle; for example, it can also be a regular polygon such as a regular hexagon, regular octagon, or regular decagon. The vibrating body 12 may also not have the through hole 12d. The vibrating body 12 can simply be plate-shaped.

[0066] Multiple protrusions 12c are provided on the second main surface 12b of the vibrating body 12. These protrusions 12c are the portions of the vibrating body 12 that contact the friction element 5. It should be noted that, without the friction element 5, the multiple protrusions 12c contact the rotor body 4a of the rotor 4. Each protrusion 12c protrudes from the second main surface 12b of the vibrating body 12 along the axial direction Z. When viewed from the axial direction Z, the multiple protrusions 12c are arranged in a circular shape. Because the multiple protrusions 12c protrude from the second main surface 12b along the axial direction Z, when traveling waves are generated in the vibrating body 12, the leading ends of the multiple protrusions 12c are further displaced significantly. Therefore, the rotor 4 can be effectively rotated by the traveling waves generated in the stator 6. It should be noted that the multiple protrusions 12c may not be necessary.

[0067] As described above, the vibrator 12 is made of a suitable metal. However, the vibrator 12 does not necessarily have to be made of metal. For example, the vibrator 12 can also be made of other elastomers such as ceramics, silicon materials, or synthetic resins. However, the vibrator 12 is preferably made of metal. This allows the vibrator 12 to be electrically connected to a ground potential, thus simplifying wiring.

[0068] Figure 9 This is a front cross-sectional view of the third piezoelectric element in the first embodiment.

[0069] The third piezoelectric element 13C 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 are opposite to each other. The third piezoelectric element 13C 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 first piezoelectric element 13A, the second piezoelectric element 13B, and the fourth piezoelectric element 13D are also constructed in the same manner as the third piezoelectric element 13C.

[0070] Next, the driving method of the ultrasonic motor 1 will be explained.

[0071] use Figure 10 The driving circuit shown provides a first signal and a second signal to the piezoelectric elements 13A, 13C, 13B, and 13D, respectively.

[0072] It should be noted that the construction of distributing multiple piezoelectric elements in the stator 6 along the circumferential direction and generating a traveling wave by driving is disclosed, for example, in WO2010 / 061508A1. It should also be noted that the construction for generating this traveling wave is not limited to the following description; the structure described in WO2010 / 061508A1 is also referenced in this specification, thus omitting detailed descriptions.

[0073] Figure 11 Images (a) through (c) are schematic bottom views used to more easily illustrate the traveling wave described above. It should be noted that... Figure 11 In (a) to (c), the grayscale image shows that the closer to black, the greater the stress in one direction; and the closer to white, the greater the stress in another direction. Figure 11 (a) shows the standing wave X of the three waves. Figure 11 (b) shows a standing wave Y of three waves. The first piezoelectric element 13A to the fourth piezoelectric element 13D are arranged at an angle 30° apart from each other. Each piezoelectric element has a circumferential dimension occupying a central angle of 60°. In this case, the standing waves X and Y of the three waves are excited, therefore, the central angle relative to the wavelength of the traveling wave becomes 120°. That is, the first piezoelectric element 13A to the fourth piezoelectric element 13D have a circumferential dimension corresponding to a central angle of 120° / 2 = 60°. Adjacent piezoelectric elements are separated by a gap corresponding to a central angle of 120° / 4 = 30°. In this case, as described above, the standing waves X and Y of the three waves with a phase difference of 90° are excited and combined to produce... Figure 11 The traveling wave shown in (c).

[0074] It should be noted that, Figure 11 In (a) to (c), A+, A-, B+, and B- represent the polarization direction of the piezoelectric element 14. + indicates polarization in the thickness direction from the third principal surface 14a toward the fourth principal surface 14b. - indicates polarization in the opposite direction. A represents the first piezoelectric element 13A and the third piezoelectric element 13C, and B represents the second piezoelectric element 13B and the fourth piezoelectric element 13D.

[0075] It should be noted that although a three-wave example is shown, it is not limited to this. In the case of nine waves, two standing waves with a 90° phase difference are also excited, and a traveling wave is generated by the synthesis of the two.

[0076] As described above, by causing the vibrator 12 to generate a traveling wave that travels in the circumferential direction, the rotor 4, which is pressed against the second main surface 12b of the vibrator 12, rotates about the axial Z-center.

[0077] It should be noted that, in this invention, the structure that generates the traveling wave is not limited to... Figure 11 The structure shown can utilize various previously known structures for generating traveling waves.

[0078] Figure 12 This is a top view showing the third piezoelectric element in a first variation of the first embodiment, with the insulating cover omitted.

[0079] In this variation, the routing of the first wiring 27A and the second wiring 27B near the third piezoelectric element 13C, as well as the arrangement of the insulating substrate 26, are different. More specifically, the insulating substrate 26 covers the second side 13b and the fourth side 13d of the third piezoelectric element 13C. When viewed from the Z-axis, the second wiring 27B overlaps with the second side 13b and the fourth side 13d of the third piezoelectric element 13C. A portion of the first wiring 27A extends substantially parallel to the first side 13a of the third piezoelectric element 13C.

[0080] In this modified example, similar to the first embodiment, the wiring can be routed using a single-layer wiring member 27. Therefore, the vibration efficiency of the vibrator 12 can be improved, and the rotational efficiency of the ultrasonic motor can be increased. Furthermore, the adhesive between the first wiring 27A and the third piezoelectric element 13C can be easily removed, making it less likely for stress to concentrate on the adhesive due to temperature changes.

[0081] Furthermore, in this modified example, the bonding area between the third piezoelectric element 13C and the insulating substrate 26 can be increased, thereby improving the bonding strength between the third piezoelectric element 13C and the insulating substrate 26.

[0082] However, as Figure 7 As shown, in the first embodiment, the wiring member 7 is bent vertically at the portion where it extends from the first main surface 12a of the vibrator 12 to the third piezoelectric element 13C. Therefore, at this portion, the wiring member 7 extends along the normal direction of the first main surface 12a. Similarly, the wiring member 7 is also bent vertically at the portions where it extends from the first main surface 12a to each piezoelectric element other than the third piezoelectric element 13C. However, the structure of the portions where the wiring member 7 reaches each piezoelectric element is not limited to the above description.

[0083] Figure 13 This is a schematic cross-sectional view showing the vicinity of the third piezoelectric element in a second variation of the first embodiment.

[0084] In this modified example, at the portion where the wiring member 7 extends from the first main surface 12a of the vibrator 12 to the third piezoelectric element 13C, the wiring member 7 extends obliquely relative to the normal direction of the first main surface 12a. This is achieved based on the structure of the adhesive layer 28 in this modified example. Specifically, the adhesive layer 28 is provided from the first main surface 12a of the vibrator 12 to the third piezoelectric element 13C. At the portion where the adhesive layer 28 extends from the first main surface 12a to the third piezoelectric element 13C, the thickness of the adhesive layer 28 increases as it approaches the third piezoelectric element 13C. The wiring member 7 is provided on this adhesive layer 28. Thus, the wiring member 7 extends obliquely along the shape of the adhesive layer 28. This suppresses sharp bends in the wiring member 7. Therefore, the wiring member 7 is difficult to break.

[0085] At the portion of the wiring member 7 that extends from the first main surface 12a of the vibrator 12 to the piezoelectric element other than the third piezoelectric element 13C, the wiring member 7 may also extend obliquely relative to the normal direction of the first main surface 12a. This further reduces the likelihood of the wiring member 7 breaking. It should be noted that, for the adhesive layer 28, epoxy resin, polyethylene resin, etc., can be used, for example, in the same manner as in the first embodiment.

[0086] Furthermore, in this modified example, similar to the first embodiment, the wiring can be routed using a single-layer wiring member 7. Therefore, the vibration efficiency of the vibrator 12 can be improved, and the rotational efficiency of the ultrasonic motor can be increased.

[0087] Explanation of reference numerals in the attached figures

[0088] 1…ultrasonic motor;

[0089] 2…shell;

[0090] 2A, 2B… First shell component, second shell component;

[0091] 2a...concave part;

[0092] 2b~2d…through holes;

[0093] 2e… cylindrical protrusion;

[0094] 3…bearings;

[0095] 4…rotor;

[0096] 4a…rotor body;

[0097] 4b…rotation axis;

[0098] 5…friction components;

[0099] 6…Stator;

[0100] 7…wiring components;

[0101] 8…Compression spring;

[0102] 9… connectors;

[0103] 12…vibrating body;

[0104] 12a, 12b... First principal face, second principal face;

[0105] 12c…protrusion;

[0106] 12d…through hole;

[0107] 13A~13D…First piezoelectric element~Fourth piezoelectric element;

[0108] 13a~13d…First side~Fourth side;

[0109] 14…piezoelectric elements;

[0110] 14a, 14b... Third principal face, fourth principal face;

[0111] 15a, 15b… First electrode, second electrode;

[0112] 16…Insulating substrate;

[0113] 16a, 16b... First substrate main surface, second substrate main surface;

[0114] 16c…opening;

[0115] 17A, 17B... First wiring, second wiring;

[0116] 17C…grounding wiring;

[0117] 17a~17d…First comb-like part~Fourth comb-like part;

[0118] 18…Insulating cover;

[0119] 18a…Incision area;

[0120] 26…Insulating substrate;

[0121] 27…wiring components;

[0122] 27A, 27B… First wiring, second wiring;

[0123] 28… Adhesive layer.

Claims

1. An ultrasonic motor, wherein, The ultrasonic motor has the following features: A stator having a plate-shaped vibrating body and a plurality of piezoelectric elements, the vibrating body including a first main surface and a second main surface opposite to each other, the plurality of piezoelectric elements being disposed on the first main surface of the vibrating body; The rotor is in direct or indirect contact with the second principal surface of the vibrating body; as well as A wiring component has an insulating substrate and a first wiring and a second wiring. The insulating substrate is disposed on the first main surface of the vibrating body, and the first wiring and the second wiring are disposed on the insulating substrate. When the first and second principal surfaces of the vibrating body are connected along the axis of rotation, the plurality of piezoelectric elements are distributed along the direction of a traveling wave that surrounds the axis, such that the traveling wave is generated by vibrating the vibrating body. The plurality of piezoelectric elements includes a first piezoelectric element, a second piezoelectric element, a third piezoelectric element, and a fourth piezoelectric element. When viewed from the axial direction, the first piezoelectric element and the third piezoelectric element are positioned opposite each other across the center of the traveling wave, and the second piezoelectric element and the fourth piezoelectric element are positioned opposite each other across the center of the traveling wave. The first and second wirings of the wiring component are single-layered, and the first, second, third, and fourth piezoelectric elements are connected to one of the first and second wirings in the same direction along the axial direction. The first wiring of the wiring component is electrically connected to the first piezoelectric element and the third piezoelectric element, and the second wiring is electrically connected to the second piezoelectric element and the fourth piezoelectric element. When viewed from the axial direction, the second wiring extends from the second piezoelectric element side through the third piezoelectric element and toward the fourth piezoelectric element side.

2. The ultrasonic motor according to claim 1, wherein, When viewed from the axial direction, the insulating substrate of the wiring member has an opening located on the third piezoelectric element. The portion of the first wiring connected to the third piezoelectric element is located within the opening of the insulating substrate, and a portion of the outer periphery of the third piezoelectric element is located within the opening.

3. The ultrasonic motor according to claim 1 or 2, wherein, The wiring component has an insulating cover that covers the first wiring and the second wiring.

4. The ultrasonic motor according to claim 1 or 2, wherein, At least any one of the following portions has a comb-like portion: the portion of the first wiring connected to the first piezoelectric element, the portion of the first wiring connected to the third piezoelectric element, the portion of the second wiring connected to the second piezoelectric element, and the portion of the second wiring connected to the fourth piezoelectric element.

5. The ultrasonic motor according to claim 1 or 2, wherein, The portion of the first wiring connected to the third piezoelectric element has a comb-like shape. The comb-like portion is shaped like a comb facing the outer periphery of the third piezoelectric element. The comb-like portion is a comb-like shape facing inward when viewed from the axial direction.

6. The ultrasonic motor according to claim 1 or 2, wherein, The wiring component also includes a grounding wire, which is electrically connected to the vibrating body and, via the vibrating body, to the ground potential. The grounding wiring is a single layer and has a portion disposed on the insulating substrate and a portion disposed on the first main surface of the vibrator.

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