Vibration actuator, and pan head and electronic device having the same

Abstract

To provide a vibration type actuator in which cracks or chipping less likely occur at an end of a hardened contact surface than a prior art.SOLUTION: A vibration type actuator includes: a first member having an elastic body and an electromechanical energy conversion element; and a second member that comes in contact with the elastic body and moves relative to the vibration body by vibration generated by an AC voltage applied to the electromechanical energy conversion element. The second member has a contact surface in contact with the first member and subjected to hardening processing and an inclined surface in contact with the contact surface and inclined against the contact surface. A coating film is formed on the inclined surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vibration actuator, and a camera platform and electronic device having the same. [Background technology]

[0002] Due to its characteristics of being capable of low-speed and high-torque driving, vibration actuators have been put to practical use, for example, as autofocus drive motors in the photographic lenses of single-lens reflex cameras. In recent years, they are also expected to be used in various electronic devices other than cameras. For example, vibration actuators are expected to be used to drive the joints of robot arms and the rotation of robot hands, to drive the pan heads of imaging devices such as surveillance cameras, and to drive the photosensitive drums of image forming devices.

[0003] In such applications other than lens driving, the actuator is generally driven more frequently than in lens driving applications, and therefore there is a demand for improved durability of the vibration actuator.

[0004] Patent Document 1 discloses a contact body (moving body) in a vibration actuator that comes into contact with a vibrating body and moves relative to the vibrating body. It also discloses a technology for improving wear resistance by forming a hardened (nitrided) surface layer (contact surface) on the contact surface (sliding part) that comes into contact with the vibrating body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-211755 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, hardening treatment increases brittleness as well as hardness. Therefore, while the vibration actuator described in Patent Document 1 has improved wear resistance compared to a non-hardened actuator, it has a problem in that cracks and chips are more likely to occur at the edge of the hardened surface layer (contact surface).

[0007] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a vibration actuator in which cracks and chips are less likely to occur at the ends of the hardened contact surface than in the prior art. [Means for solving the problem]

[0008] The vibration actuator of the present invention includes a first member having an elastic body and an electromechanical energy conversion element; The elastic body is brought into contact with the electromechanical energy conversion element, and the vibration generated in the electromechanical energy conversion element causes the First Part and a second member that moves relative to the first member, The second member includes: in contact with the first member; Both are nitrided contact surface and an inclined surface connected to the contact surface and inclined relative to the contact surface; A coating is formed on the inclined surface. And, A region located on the back surface of the coating and having a smaller nitrogen content than a region adjacent to the contact surface is provided. It is characterized by:

[0009] The vibration actuator of the present invention includes a first member having an elastic body and an electromechanical energy conversion element; The elastic body is brought into contact with the electromechanical energy conversion element, and the vibration generated in the electromechanical energy conversion element causes the First Part and a second member that moves relative to the first member, The first member includes: contacting the second member; Both are nitrided contact surface and an inclined surface connected to the contact surface and inclined relative to the contact surface; A coating is formed on the inclined surface. And, A region located on the back surface of the coating and having a smaller nitrogen content than a region adjacent to the contact surface is provided. It is characterized by: Effect of the Invention

[0010] According to the above invention, it is possible to provide a vibration actuator in which cracks and chips are less likely to occur at the edge of the hardened contact surface than in the prior art. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a vibration actuator according to a first embodiment of the present invention. [Diagram 2] 2A and 2B are cross-sectional views each showing a schematic configuration of a contact body in FIG. 1, and FIG. 2B is an enlarged cross-sectional view. [Diagram 3] 2 is a process diagram showing a method for producing the contact body in FIG. 1. [Figure 4] 1. FIG. 4 is an enlarged cross-sectional view that illustrates a schematic configuration of a first modified example of the contact body in FIG. [Diagram 5] 2A and 2B are cross-sectional views each showing a schematic configuration of a second modified example of the contact body in FIG. 1, in which FIG. [Figure 6] 1. FIG. 4 is a cross-sectional view and an enlarged cross-sectional view showing a configuration of a third modified example of the contact body in FIG. [Figure 7] FIG. 11 is an exploded perspective view showing a schematic configuration of a vibration actuator according to a second embodiment of the present invention. [Figure 8] 8A and 8B are cross-sectional views each showing a schematic configuration of a vibrating body in FIG. 7, in which FIG. 8A is a cross-sectional view and FIG. 8B is an enlarged cross-sectional view. [Figure 9] 10A, 10B, and 10C are respectively a top view, a cross-sectional view along the CC section, and an enlarged cross-sectional view along the CC section, each showing a schematic configuration of a vibration actuator according to a third embodiment of the present invention. [Figure 10] 1 is a cross-sectional view showing a schematic configuration of a camera platform on which a vibration actuator according to an embodiment of the present invention is mounted, and an imaging device mounted on the camera platform. [Figure 11] 1 is a top view showing a schematic configuration of an imaging device equipped with a vibration actuator according to an embodiment of the present invention. [Figure 12]1 is a perspective view showing a schematic configuration of an MRI diagnostic apparatus equipped with a vibration actuator according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0013] Example 1 1 is a cross-sectional view showing a schematic configuration of a vibration actuator 10 according to a first embodiment of the present invention. The mechanical configuration of the vibration actuator 10, including a vibrating body 20, a contact body 300 (moving body, driven body), and a pressure mechanism 40, is functionally equivalent to that of the vibration actuator described in, for example, JP 2017-108615 A.

[0014] The vibration actuator 10 of this embodiment includes a vibrating body 20 (first member) having an elastic body 21 and an electromechanical energy conversion element 22, and a contact body 300 (second member) in contact with the vibrating body 20. In addition, the vibration actuator 10 includes a power supply member (flexible printed circuit board) 50 that supplies power to the electromechanical energy conversion element 22.

[0015] 1, the vibration actuator 10 includes a vibrating body 20 (first member) formed in an annular shape, a contact body 300 (second member) formed in an annular shape, and a pressure mechanism 40. The vibration actuator 10 also includes a shaft, a housing, a bearing, and a screw.

[0016] The vibrating body 20 (first member) has an elastic body 21, a piezoelectric element 22 which is an electro-mechanical energy conversion element joined to the elastic body 21, and a power supply member 50 which is joined to the piezoelectric element 22 for applying a driving voltage which is an AC voltage to the piezoelectric element 22.

[0017] The pressure mechanism 40 has a vibration-damping rubber 41, a pressure spring receiving member 42, a pressure spring receiving rubber 43, a pressure spring 44 (pressure member), and a pressure spring fixing member 45. The vibrating body 20 (first member) and the contact body 300 (second member) are arranged concentrically with the shaft as the central axis, and are brought into pressure contact (frictional contact) with each other in the thrust direction of the shaft by the pressure mechanism 40 fixed to the shaft. Specifically, the pressure spring 44 (pressure member) whose movement is restricted by the pressure spring fixing member 45 fixed to the shaft presses the contact body 300 (second member) in the thrust direction via the vibration-damping rubber 41, the pressure spring receiving member 42, and the pressure spring receiving rubber 43. By being configured in this way, the contact body 300 (second member) and the vibrating body 20 (first member) are stably contacted with each other.

[0018] In the vibration actuator 10, a driving voltage, which is an AC voltage, is applied to the piezoelectric element 22 through the power supply member 50 to excite a driving vibration in the vibrating body 20 (first member). The form of the driving vibration depends on the number and arrangement of the electrodes of the piezoelectric element 22, but the piezoelectric element 22 is designed so that the excited driving vibration becomes an n-th order traveling wave that advances in the circumferential direction of the vibrating body 10. The n-th order driving vibration is a bending vibration in which the number of waves in the circumferential direction of the vibrating body 20 (first member) is n. The driving vibration generated in the piezoelectric element 22 drives the contact body 300 (second member) in the circumferential direction around the shaft by the traveling wave generated in the vibrating body 20 (first member). That is, the contact body 300 (second member) rotates relatively to the vibrating body 20 (first member) while maintaining its concentricity. The rotational force generated in the contact body 300 (second member) is output to the outside through the pressure mechanism 40 and the shaft.

[0019] 1, the housing of the vibration actuator 10 according to the present embodiment can be fixed to a desired member and a movable object such as a camera can be freely rotated by fixing the housing to the shaft. On the other hand, it is also possible to fix the shaft and rotate the housing.

[0020] 2(a) is a cross-sectional view showing a schematic configuration of the contact body 300 (second member). The contact body 300 (second member) has a main body portion 301 (base portion) which serves as a base, and a spring portion 302 which extends in an annular shape in the inner diameter direction from the main body portion 301 (base portion) and has spring properties in the pressure direction of the pressure spring 44 (pressure member). The end of the spring portion 302 has a contact surface 303 which comes into pressure contact with the vibrating body 20 (first member).

[0021] The direction in which the spring portion 302 extends intersects with the pressure direction in which the pressure spring 44 (pressure member) presses and contacts the contact body 300 (second member) and the vibrating body 20 (first member). The spring portion 302 is formed with a thickness that has springiness in the pressure direction of the pressure spring 44 (pressure member) (has springiness against the pressure force of the pressure member). This allows the contact body 300 (second member) to be stably contacted with the vibrating body 20 (first member).

[0022] FIG. 2(b) is a cross-sectional view that shows a schematic configuration of the spring portion 302 of the contact body 300 (second member). The main body portion 301 (base portion) and the spring portion 302 have a base material 304 made of an iron-based material such as austenitic stainless steel. The base material is made of an iron-based material in order to perform a hardening treatment (nitriding treatment). A nitride layer 306 is formed on the contact surface 303 with the vibrating body 20 (first member), and a coating 305 made of a metal material other than the iron material is formed on the surface excluding the contact surface 303. The coating is made of a metal material other than the iron material in order to prevent the hardening treatment (nitriding treatment).

[0023] Since the spring portion 302 has spring properties and is deformed by repeatedly receiving a load when the vibration actuator is driven, there is a risk that cracks or chips will occur in the coating 305, or that the coating 305 will peel off from the substrate 304. Cracks, chips, or peeling will change the spring constant and resonance frequency of the spring portion 302, causing squeals and abnormal noises when the vibration actuator is driven, so it is important to take measures against cracks and chips in the coating 305 and against peeling of the coating 305.

[0024] On the outer diameter side of the nitride layer 306, a first inclined surface 307 is formed which is connected to the contact surface 303 and inclined with respect to the contact surface 303, and the nitride layer 306 is covered with a coating 305. In other words, the coating 305 is formed on the first inclined surface 307. On the inner diameter side of the nitride layer 306, a second inclined surface 307 is formed which is connected to the contact surface 303 and inclined with respect to the contact surface 303. 8 is formed, and the nitride layer 306 is covered with the coating 305. That is, the coating 305 is formed on the second inclined surface 308. The inclination angle θout of the first inclined surface 307 with respect to the contact surface 303 and the inclination angle θin of the second inclined surface 308 with respect to the contact surface 303 are both 120 degrees, which are obtuse angles. Therefore, the width of the inner and outer diameters of the nitride layer 306 is configured to expand in the depth direction from the contact surface 303.

[0025] When the vibration actuator is driven, the contact surface 303 receives a frictional force between it and the vibrating body 20 (first member). The frictional force may cause peeling at the interface between the contact surface 303 and the coating 305. However, by forming a first inclined surface 307 and a second inclined surface 308 that are connected to the contact surface 303 and inclined relative to the contact surface 303, the component of the frictional force perpendicular to the coating 305 is reduced, and peeling of the coating 305 is suppressed.

[0026] The thickness of the coating 305 is configured to be thin in order to reduce the effect on the spring constant of the spring portion 302 and to suppress the occurrence of cracks and chipping due to the internal stress of the coating. The thickness of the coating 305 is preferably 1 μm or more and 10% or less of the minimum thickness of the spring portion 302. If the thickness of the coating is less than 1 μm, defects will occur in the coating, and it will be impossible to suppress the formation of a nitride layer on the base material in the nitriding process, which is undesirable. Also, if the thickness of the coating is more than 10% of the minimum thickness of the spring portion, the effect of the coating on the spring constant of the spring portion will be large, and unevenness and variation in the thickness of the coating will increase, which is undesirable.

[0027] Specifically, the minimum thickness of spring portion 302 is several hundreds of μm to several mm, and the thickness of coating 305 is several tens of μm or less, and more preferably, the thickness of coating 305 is 10 μm or less. Note that in the drawings of this embodiment, the thickness of coating 305 is exaggerated to make the configuration of spring portion 305 easier to understand.

[0028] 3 is a process diagram showing a method for manufacturing a contact body, showing an enlarged view of spring portion 302. In a cutting process (not shown), which is a first process, base material 304 of contact body 300 (second member) including spring portion 305 is manufactured by cutting. A protrusion is formed at the tip of spring portion 302, and a first inclined surface 307 and a second inclined surface 308 that are connected to contact surface 303 and inclined relative to contact surface 303 are formed on the outer diameter and inner diameter of the protrusion, respectively. An iron-based material such as austenitic stainless steel is used for base material 304.

[0029] In the second step, the plating step, the contact body 300 (second member) including the spring portion 302 is plated to form the coating 305. The plating may be either electroplating or electroless plating. The main component of the coating 305 is copper, nickel, tin, silver, chromium, or the like, and may be any material other than an iron-based material as long as it is capable of suppressing the formation of a nitride layer on the base material 304 in the fourth step, the nitriding step.

[0030] In the third step, a polishing step, coating 305 on contact surface 303 is removed by polishing to expose substrate 304. There is a risk that coating 305 will peel off at the interface between coating 305 and contact surface 303 due to frictional force during polishing, but first inclined surface 307 and second inclined surface 308 distribute the frictional force, making it possible to reduce the force that peels off coating 305 and suppress peeling of coating 305.

[0031] In order to suppress squealing and abnormal noise when the vibration actuator is driven, it is effective to finish the flatness of the contact surface 303 with high precision. In the polishing process, after removing the coating 305, the base material 304 is polished to improve the flatness of the contact surface 303. This makes it possible to finish the flatness of the contact surface 303 with high precision even if the processes such as polishing and lapping for improving the flatness after the nitriding process, which is the fourth process, are simplified or eliminated.

[0032] In the nitriding step, which is the fourth step, the contact body 300 (second member) is placed in a nitriding furnace and subjected to nitriding treatment (hardening treatment). Nitrogen penetrates into the contact surface 303 where the base material 304 is exposed, forming a nitride layer 306. The surface on which the coating 305 is formed has the coating 305 suppressing the penetration of nitrogen into the base material 304, and the formation of a nitride layer on the base material 304 is significantly suppressed. In addition, since the nitriding treatment is a heat treatment at 400 to 600°C, the coating 305 and the base material 304 are thermally diffused to improve adhesion, and peeling of the coating 305 during operation of the vibration actuator is suppressed.

[0033] In the nitriding step, nitrogen penetrates into the base material 304, causing volume expansion during the formation of the nitride layer 306, which may cause the coating 305 in contact with the nitride layer 306 to deform and peel off. Since nitrogen penetrates from the contact surface 303 where the base material 304 is exposed, less nitrogen penetrates into the area A0 on the back side of the coating 305 on the first inclined surface 307 and the second inclined surface 308, and the volume expansion is small. Therefore, deformation of the coating 305 and peeling of the coating 305 are suppressed.

[0034] The coating 305 after the nitriding process is a material in which the plating film formed in the plating process and the base material 304 have diffused, but because the plating film does not use an iron-based material, the material of the plating film is the main component of the coating 305. For example, if nickel plating is used in the plating process, an elemental analysis of the coating 305 using EDX or the like will detect a higher nickel content (mass %) than iron content (mass %). The same is true when copper plating, chromium plating, etc. are used.

[0035] In the configuration of this embodiment, austenitic stainless steel, which is a nonmagnetic material, is used for the base material 304 of the contact body 300 (second member). This makes it possible to reduce the magnetism of the contact body 300 (second member) compared to the case where a ferromagnetic material such as martensitic stainless steel is used.

[0036] In addition, since the nitride layer 306 of an iron-based material formed on the contact body 300 (second member) has magnetism, the coating 305 prevents the formation of a nitride layer on the surfaces other than the contact surface 303. This makes it possible to reduce the magnetism of the contact body compared to a case where a nitride layer is formed on the entire surface of the contact body. Note that it is preferable to use a non-magnetic material for the coating 345.

[0037] Furthermore, by constructing all the components of the vibration actuator 10 from non-magnetic materials, it is possible to make the vibration actuator 10 non-magnetic. For example, the elastic body 21 can be made of austenitic stainless steel that has been subjected to nitriding treatment (hardening treatment), the shaft can be made of austenitic stainless steel, and the pressure spring 44 (pressure member) can be made of phosphorus bronze.

[0038] 4 is a cross-sectional view that shows a schematic configuration of a first modified example of the contact body in this embodiment, and shows a schematic configuration of spring portion 312 of contact body 310 (second member). Body portion 311 (base portion) and spring portion 312 have substrate 314 made of an iron-based material such as austenitic stainless steel. A nitride layer 316 is formed on contact surface 313 with vibrating body 20 (first member), and a coating 315 is formed on the surface excluding contact surface 313.

[0039] A first inclined surface 317 is formed on the outer diameter side of the nitride layer 316, which is connected to the contact surface 313 and inclined with respect to the contact surface 313, and the nitride layer 316 is covered with the coating 315. In other words, the coating 315 is formed on the first inclined surface 317. No inclined surface is formed on the inner diameter side of the nitride layer 316. The inclination angle θ of the first inclined surface 317 with respect to the contact surface 313 outis 120 degrees, which is an obtuse angle. With the configuration of this modification, cutting of the inclined surface on the inner diameter side during manufacturing can be omitted. Note that the inclined surface may be formed only on the inner diameter portion, and not on the outer diameter portion. The configuration of this modification can also obtain the same effect as this embodiment. The frictional force acting on the contact surface 313 during driving of the vibration actuator and during the polishing process during manufacturing can be dispersed by the first inclined surface 317, thereby suppressing peeling of the coating 315. Furthermore, the first inclined surface 317 can suppress expansion of the area A1 on the back side of the coating 315 during the nitriding process, thereby suppressing peeling of the coating 315.

[0040] FIG. 5(a) is a cross-sectional view showing a schematic configuration of a second modified example of the contact body in this embodiment. In this embodiment, the spring part has a cantilever beam configuration, but in this modified example, the spring part has a doubly supported beam configuration. The contact body 320 (second member) includes a main body part 321 (base part) and a spring part 322. The main body part 321 (base part) includes a first main body part 321-1 (first base part) and a second main body part 321-2 (second base part) that are concentrically arranged. The spring part 322 extends radially from the first and second main body parts to connect the two main body parts (base parts). The spring part 322 has a contact surface 323 near the center in the radial direction that is in pressure contact with the vibrating body 20 (first member). The direction in which the spring portion 322 extends intersects with the pressure direction of the contact body 320 (second member) and the vibrating body 20 (first member), and is formed with a thickness that provides springiness against pressure. This allows the contact body 320 (second member) to be stably contacted with the vibrating body 20 (first member).

[0041] FIG. 5(b) is a cross-sectional view that shows a schematic configuration of the spring portion 322 of the contact body 320 (second member) in the second modified example. The main body portion 322 (base portion) and the spring portion 322 have a base material 324 made of an iron-based material such as austenitic stainless steel. A nitride layer 326 is formed on a contact surface 323 with the vibrating body 20 (first member), and a coating 325 is formed on the surface except for the contact surface 323. A first inclined surface 327 that is connected to the contact surface 323 and inclined with respect to the contact surface 323 is formed on the outer diameter side of the nitride layer 326, and the nitride layer 326 is covered with the coating 325. That is, the coating 325 is formed on the first inclined surface 327. A second inclined surface 328 that is connected to the contact surface 323 and inclined with respect to the contact surface 323 is formed on the inner diameter side of the nitride layer 326, and the nitride layer 326 is covered with the coating 325. That is, the coating 325 is formed on the second inclined surface 328. The inclination angle θ of the first inclined surface 327 with respect to the contact surface 323 out and the inclination angle θ of the second inclined surface with respect to the contact surface 323. in are both 110 degrees, which are obtuse angles. The inclined surface may be on either the inner or outer diameter. The configuration of this modified example can also provide the same effects as this embodiment. The frictional force acting on the contact surface 323 during driving of the vibration actuator and during the polishing process during manufacture can be dispersed by the first inclined surface 327 and the second inclined surface 328, thereby suppressing peeling of the coating 325. Furthermore, the first inclined surface 327 and the second inclined surface 328 can suppress expansion of the area A1 on the back side of the coating 325 during the nitriding process, thereby suppressing peeling of the coating 325.

[0042] 6(a) is a cross-sectional view showing a schematic configuration of a third modified example of the contact body in this embodiment. In this embodiment, the spring part and the main body part (base part) are an integrated part manufactured by cutting the same material, but in this modified example, the spring part and the main body part (base part) are separate parts, and the two parts are bonded and joined together.

[0043] The contact body 330 (second member) includes a main body member 331 and a spring member 339. The main body member 331 and the spring member 339 are concentrically arranged, fitted together, and bonded. The main body member 331 is a component manufactured by cutting a free-cutting material such as brass or an aluminum alloy, and the spring member 339 is a component manufactured by pressing an iron-based material such as an austenitic stainless steel. The spring portion 332 extends in the axial direction from the fitting portion with the main body member 331, bends diagonally toward the inner diameter direction from the middle, and has a contact surface 333 at the tip that comes into pressure contact with the vibrating body 20 (first member). The portion between the fitting portion and the contact surface 333 is the spring portion 332. The direction in which the spring portion 332 extends intersects with the pressure direction of the contact body 330 (second member) and the vibrating body 20 (first member), and is formed with a thickness that provides springiness against pressure. This allows the contact body 330 (second member) to be brought into stable contact with the vibrating body 20 (first member).

[0044] FIG. 6(b) is a cross-sectional view that shows a schematic configuration of the spring portion 332 of the contact body 330 (second member) in the third modified example. The spring portion 332 has a base material 334 made of an iron-based material such as austenitic stainless steel. A nitride layer 336 is formed on a contact surface 333 with the vibrating body 20 (first member), and a coating 335 is formed on the surface except for the contact surface 333. A first inclined surface 337 that is connected to the contact surface 333 and inclined with respect to the contact surface 333 is formed on the outer diameter side of the nitride layer 336, and the nitride layer 336 is covered with the coating 335. That is, the coating 335 is formed on the first inclined surface 337. A second inclined surface 338 that is connected to the contact surface 333 and inclined with respect to the contact surface 333 is formed on the inner diameter side of the nitride layer 336, and the nitride layer 336 is covered with the coating 335. That is, the coating 335 is formed on the second inclined surface 338. The inclination angle θ of the first inclined surface 337 with respect to the contact surface 333 out The inclination angle θ of the second inclined surface 338 with respect to the contact surface 333 is 135 degrees, which is an obtuse angle. in is 45 degrees, an acute angle.

[0045] The configuration of this modified example can also provide the same effects as those of this embodiment. The frictional force acting on the contact surface 333 during driving of the vibration actuator and during the polishing process during manufacture can be dispersed by the first inclined surface 337 and the second inclined surface 338, making it possible to suppress peeling of the coating 335. Furthermore, the first inclined surface 337 can suppress expansion of the area A2 on the back side of the coating 335 during the nitriding process, making it possible to suppress peeling of the coating 335.

[0046] In this embodiment, specific values ​​of the inclination angle of the inclined surface with respect to the contact surface are shown, but in order to suppress peeling of the coating due to frictional force, it is sufficient that the inclination angle is not perpendicular. In order to suppress peeling of the coating due to expansion of the nitride layer, the inclination angle needs to be an obtuse or acute angle, and is preferably 5 degrees or more and 80 degrees or less, or 100 degrees or more and 175 degrees or less.

[0047] If the angle is outside these ranges, that is, greater than 80 degrees or less than 100 degrees, the effect of the coating in dispersing the frictional force and preventing peeling of the coating is not sufficiently suppressed, and the effect of the coating in preventing cracks and chips from occurring at the edge of the hardened contact surface is reduced, which is undesirable. Also, if the angle is outside these ranges, that is, less than 5 degrees or greater than 175 degrees, the area other than the area where the contact surface and the vibrator contact (the area where the coating and the vibrator contact) occupies in the area where the contact body and the vibrator contact each other becomes large. As a result, an unintended contact state occurs, and the desired drive characteristics cannot be obtained, which is undesirable.

[0048] In this embodiment, the coating is formed on all surfaces of the spring portion except the contact surface, but the present invention is not limited to this configuration. The effect of this embodiment can be obtained as long as the coating is formed on only a part of the spring portion.

[0049] Example 2 Fig. 7 is an exploded perspective view showing a schematic configuration of a vibration actuator according to Example 2 of the present invention. A vibration actuator 400 shown in Fig. 7 is a device capable of linear driving, and includes a vibrating body 32 (first member) and a contact body 33 (second member) that move relative to each other.

[0050] The vibrating body 32 (first member) has an elastic body 32b, two protrusions 32d provided on one surface of the elastic body 32b, and a piezoelectric element 32a provided on the surface opposite to the surface on which the protrusions 32d are provided. Note that at least one protrusion 32d is sufficient to drive the contact body 33 (second member).

[0051] The piezoelectric element 32a is bonded to the elastic body 32b by an adhesive. The piezoelectric element 32a has a structure in which electrodes of a predetermined shape are formed on both sides of a plate-shaped piezoelectric ceramic. A driving voltage (AC voltage) of a predetermined frequency is applied to the electrodes of the piezoelectric element 32a to excite the vibration of the vibration body 32 (first member) in two vibration modes, and the protrusions 32d are caused to perform elliptical motion in a plane including a direction connecting the two protrusions 32d and a protruding direction of the protrusions 32d. As a result, the protrusions 32d frictionally drive the contact body 33 (second member), and the contact body 33 (second member) and the vibration body 32 (first member) can be linearly driven relative to each other. The principle of causing the vibration body 32 (first member) to perform elliptical motion is well known, so a detailed description thereof will be omitted here.

[0052] The vibrating body 32 (first member) is held and fixed by a supporting member 119. The supporting member 119 is movable in the X direction while being guided by two guide bars 122, which are two guide members arranged parallel to the X direction in Fig. 6. The two guide bars 122 are fixed in a state where they are sandwiched between two driven body holding members 123 and 124 fixed to a bottom plate 121.

[0053] The vibrating body 32 (first member) is fixed by screws via a holding member 109 to a fixing portion 119d provided on the supporting member 119. This allows the supporting member 119 and the vibrating body 32 (first member) to move integrally in the X direction.

[0054] Between the support member 119 and the vibrating body 32 (first member), a pressure spring 125 is disposed, which is a pressure means having a leaf spring shape and generating a spring force by bending in the Z direction. The free end of the pressure spring 125 is in contact with the vibrating body 32 (first member) and presses the vibrating body 32 (first member) against the contact body 33 (second member). In order to realize a desired pressurized contact state, the vibrating body 32 (first member) and the contact body 33 (second member) need to be relatively displaceable in the Z direction. In this embodiment, a part of the holding member 109 is elastically deformed, so that the vibrating body 32 (first member) and the contact body 33 (second member) are relatively displaceable in the Z direction.

[0055] In the vibration actuator 400, the support member 119 that slides in the X direction together with the vibrating body 32 (first member) serves as output means to extract a driving force (or displacement) to drive any device.

[0056] FIG. 8(a) is a cross-sectional view showing a schematic configuration of the vibrating body in this embodiment. The elastic body 32b has a main body portion 341 (base portion) and a disk-shaped spring portion 342 at the tip of two cylindrical protrusions 32d provided on the main body portion 341 (base portion). The center of the spring portion 342 has a circular contact surface 343 that is in pressure contact with the contact body 33 (second member). The direction in which the spring portion 342 extends intersects with the pressure direction of the contact body 33 (second member) and the elastic body 32b, and is formed with a thickness that has spring properties against pressure. This allows the contact body 33 (second member) to be stably contacted with the elastic body 32b.

[0057] 8(b) is a cross-sectional view showing a schematic configuration of the spring part 342 of the vibrating body 32 (first member) in this embodiment. The main body part 341 (base part) and the spring part 342 have a base material 344 made of an iron-based material such as austenitic stainless steel. A nitride layer 346 is formed on a contact surface 343 with the vibrating body 32 (first member), and a coating 345 made of a metal material other than the iron-based material is formed on the surface excluding the contact surface 343.

[0058] A first inclined surface 347 is formed around the nitride layer 346 in a circumferential manner, connected to the contact surface 343, and inclined with respect to the contact surface 343, and the nitride layer 346 is covered with the coating 345. In other words, the coating 345 is formed on the first inclined surface 347. The inclination angle θ of the first inclined surface 347 with respect to the contact surface 343 is 150 degrees, which is an obtuse angle. Therefore, the diameter of the nitride layer 346 increases in the depth direction from the contact surface 333.

[0059] The thickness of coating 345 is configured to be thin in order to reduce the effect on the spring constant of spring portion 342 and to suppress the occurrence of cracks and chipping due to internal stress of the coating. It is preferable that the thickness of coating 345 is 10% or less of the thickness of spring portion 342. Specifically, the thickness of spring portion 342 is several hundreds of μm to several mm, and the thickness of coating 345 is several tens of μm or less, and more preferably the thickness of coating 345 is 10 μm or less. Note that the thickness of coating 345 is exaggerated in FIG. 8 to make it easier to understand the configuration of spring portion 345.

[0060] The elastic body 32b of this embodiment can be manufactured by the same method as the contact body described in the first embodiment. In this modification, the first step of forming the base material 341 can be achieved by pressing an austenitic stainless steel plate. The second step, which is a plating step, the third step, which is a polishing step, and the fourth step, which is a nitriding step, are the same as those of the first embodiment. After the nitriding step, the coating 345 on the bonding surface of the elastic body 32b with the piezoelectric element 32a is removed by polishing, thereby enabling the piezoelectric element 32a to be firmly bonded.

[0061] The configuration of this modified example can also provide the same effects as this embodiment. The frictional force acting on the contact surface 323 during driving of the vibration actuator and during the polishing process during manufacture can be dispersed by the first inclined surface 347, thereby suppressing peeling of the coating 345. Furthermore, the first inclined surface 347 can suppress expansion of the area A3 on the back side of the coating 345 during the nitriding process, thereby suppressing peeling of the coating 345.

[0062] In the configuration of this embodiment, the base material 344 of the elastic body 32b is made of austenitic stainless steel, which is a nonmagnetic material, and thus the magnetism of the elastic body 32b can be reduced compared to when a ferromagnetic material such as martensitic stainless steel is used. In addition, since the nitride layer 346 of the iron-based material formed on the elastic body 32b has magnetism, the coating 345 prevents the formation of a nitride layer on the surface other than the contact surface 343. This reduces the magnetism of the contact body compared to when a nitride layer is formed on the entire surface of the contact body. It is preferable to use a nonmagnetic material for the coating 345. Furthermore, the vibration actuator 10 can be made nonmagnetic by constructing the components other than the elastic body 32b constituting the vibration actuator 400 from a nonmagnetic material. For example, the contact body 33 (second member) can be made of austenitic stainless steel that has been subjected to a nitriding treatment (hardening treatment), the guide bar 122 can be made of austenitic stainless steel, and the pressure spring 125 can be made of phosphor bronze.

[0063] In this embodiment, a specific value of the inclination angle of the inclined surface with respect to the contact surface is shown, but in order to suppress peeling of the coating due to frictional force, it is not necessary that the angle is perpendicular. In order to suppress peeling of the coating due to the expansion of the nitride layer, the angle needs to be obtuse, and is preferably 100 degrees or more and 175 degrees or less. If the angle is out of this range and is less than 100 degrees, the effect of the coating in dispersing the frictional force and suppressing peeling of the coating sufficiently decreases, and it is not preferable. Also, if the angle is out of this range and is greater than 175 degrees, the area other than the area where the contact surface and the vibrator contact each other (the area where the coating and the vibrator contact each other) becomes large in the area where the contact body and the vibrator contact each other. As a result, an unintended contact state occurs, and the desired driving characteristics cannot be obtained, which is not preferable.

[0064] In this embodiment, the coating 345 is formed on all surfaces of the spring portion 342 except the contact surface 343, but this is not limiting. The effect of this embodiment can be obtained as long as the coating 345 is formed on only a part of the spring portion 342.

[0065] Example 3 9A, 9B, and 9C are respectively a top view, a cross-sectional view along the CC section, and an enlarged cross-sectional view along the CC section, and are schematic diagrams showing the configuration of a contact body of a vibration actuator according to a third embodiment of the present invention.

[0066] The vibration actuator of this embodiment differs from the vibration actuator described in Example 1 in that only the configuration of the contact body is different, and the other configurations and driving principles are the same as those described in Example 1. The contact body of Example 1 has been described as having a configuration in which a contact surface with the vibrating body is formed on a part of the spring part, but the contact body of this embodiment has a friction member (contact member) bonded (fitted) to the tip of the spring part, and a part of the friction member (contact member) forms the contact surface with the vibrating body.

[0067] The contact body 360 is composed of a main body member 350 having a main body portion 351 (base portion) and a spring portion 352, and a friction member 359 (contact member). The main body portion 351 (base portion) and the spring portion 352 are made of a free-cutting material such as an aluminum alloy, and are manufactured by cutting or the like.

[0068] The friction member 359 (contact member) has a substantially L-shaped cross section, is adhered or joined to the spring portion 352, and has a contact surface 353 that comes into pressurized contact with the vibrating body 20 (first member). The friction member 359 (contact member) has a base material 354 made of an iron-based material such as austenitic stainless steel. It is manufactured by pressing, cutting, or the like. In FIG. 9, the friction member 359 (contact member) is inclined in cross section and in contact with the main body member 350 including the main body portion 351 (base portion) and the spring portion 352 at two points, but it may be in contact on a surface without being inclined.

[0069] The spring portion 352 extends in the radial direction from the main body portion 351 (base portion). The direction in which the spring portion 352 extends intersects with the pressure direction of the contact body 360 and the vibrating body 20 (first member), and is formed with a thickness that provides springiness against pressure. This allows the contact body 360 to be stably in contact with the vibrating body 20 (first member).

[0070] A nitride layer 356 is formed on a contact surface 353 of a friction member 359 (contact member) that comes into contact with the vibration body 20 (first member), and a coating 355 is formed on the surface excluding the contact surface 353 .

[0071] A first inclined surface 357 that is connected to the contact surface 353 and inclined with respect to the contact surface 353 is formed on the outer diameter side of the nitride layer 356, and the nitride layer 356 is covered with the coating 355. In other words, the coating 355 is formed on the first inclined surface 357.

[0072] A second inclined surface 358 is formed on the inner diameter side of the nitride layer 356, the second inclined surface 358 being connected to the contact surface 353 and inclined with respect to the contact surface 353, and the nitride layer 356 is covered with the coating 355. In other words, the coating 355 is formed on the second inclined surface 358.

[0073] The inclination angle θout of the first inclined surface 357 relative to the contact surface 353 is 175 degrees, and the inclination angle θin of the second inclined surface relative to the contact surface 353 is 155 degrees, which are both obtuse angles. The inclined surface may be on either the inner or outer diameter.

[0074] The configuration of this embodiment can also provide the same effects as those of Example 1. The frictional force acting on the contact surface 353 during driving of the vibration actuator and during the polishing process during manufacture can be dispersed by the first inclined surface 357 and the second inclined surface 358, thereby suppressing peeling of the coating 355. Furthermore, the first inclined surface 357 and the second inclined surface 358 can suppress expansion of the area on the back side of the coating 355 (the area corresponding to area A1 in FIG. 4) during the nitriding process, thereby suppressing peeling of the coating 355.

[0075] In addition, in Examples 1, 2 and 3, nitriding was used as the hardening treatment, but carburizing may also be used as the hardening treatment in addition to nitriding.

[0076] Example 4 In the fourth embodiment, a configuration of a camera platform for an imaging device such as a surveillance camera will be described as an example of a device including the vibration actuator 10 described in the first embodiment.

[0077] In this embodiment, a pan head including a rotating table (base) and a vibration type actuator provided on the rotating table (base) will be described below.

[0078] figure 10 , the tripod head 2 00 and the tripod head 2 Imaging device installed in 00 2 FIG. 4 is a diagram showing a schematic configuration of the camera platform 40. 2 00 is the base 2 20 and two vibration actuators 2 70, 2 Head with 80 2 10 and an imaging device 2 L angle for fixing 40 2 30. A vibration actuator provided on the pan axis 2 80 head 2 10 and L angle 2 30 and imaging device 2 40, base 2 20 around the pan axis. Also, a vibration actuator provided on the tilt axis 2 70 is L angle 2 30 and imaging device 2 40, Head 2 10 is an actuator for rotating the tilt sensor 10 around the tilt axis.

[0079] By using two vibration actuators 870, 880 in the camera platform 800, it becomes possible to change the orientation of the imaging device 840 at high speed, with high response, quietly, and with high precision. In addition, since the vibration actuator has a high holding torque even when not energized, the orientation of the imaging device 840 can be maintained without consuming power from the vibration actuator even if the center of gravity of the imaging device 840 is misaligned around the tilt axis.

[0080] In addition, it is possible to provide an electronic device that includes a member desired by a user of the present invention and a vibration type actuator provided on the member.

[0081] Example 5 In the fifth embodiment, a configuration of an imaging device will be described as an example of a device including the linear vibration actuator described in the second embodiment.

[0082] figure 11 FIG. 5 is a top view showing a schematic configuration of an imaging device 500 including a linear vibration actuator of a second embodiment. The imaging device 500 includes an imaging device body 501 having an imaging element (not shown), and a lens barrel 502 that is detachable from the imaging device body 501. The lens barrel 502 includes a plurality of lens groups 503, a focus adjustment lens 504, and a vibration actuator 510. A lens holding frame (not shown) that holds the focus adjustment lens 504 is connected to a contact body in the vibration actuator 510. By driving the vibration actuator 510, the focus adjustment lens 504 can be driven in the optical axis direction to focus on a subject.

[0083] When a zoom lens is arranged in the lens barrel 502, the vibration actuator 510 can also be used as a drive source for moving the zoom lens in the optical axis direction. Furthermore, when an image stabilization lens is arranged in the lens barrel 502, the vibration actuator 510 can be used as a drive source for driving the image stabilization lens in a plane perpendicular to the optical axis.

[0084] Example 6 In the sixth embodiment, a puncture device for biopsy in which the rotary shaft of the rotary vibration actuator of the first embodiment made of a non-magnetic material is connected to a needle will be described. Here, an example in which the puncture device is applied to an MRI diagnostic device, which is a medical system, will be described.

[0085] figure 12 1 is a perspective view showing a schematic configuration of an MRI diagnostic apparatus 600 equipped with a puncture device 660. FIG.

[0086] Since the MRI diagnostic device 600 generates a strong magnetic field, when installing devices using magnetic materials, such as electromagnetic motors that use magnets, it is necessary to take preventive measures to prevent any influence on diagnostic images. In contrast, the vibration actuator does not use magnets, and the vibrating body and contact body are made of austenitic stainless steel, so it can be installed near or inside the MRI diagnostic device 600.

[0087] While the MRI diagnostic apparatus 600 acquires image information of the subject, a needle attached to the tip of the puncture apparatus 660 extracts a living tissue.

[0088] Specifically, the puncture device 660 is disposed near a doughnut-shaped MRI diagnostic device 600. The MRI diagnostic device 600 has a magnetic field generating unit 601 configured in a ring shape, a bore 602 which is a cylindrical portion in which a subject fits, a treatment table 603 on which the subject 604 lies, and a support table 605 which moves the treatment table 603 closer to / away from the bore 602. The puncture device 660 is disposed at a position where a needle can be inserted into the bore 602.

[0089] Based on the image information acquired by the MRI diagnostic apparatus 600, the puncture device 660 is driven to perform biological extraction using a needle.

[0090] The support table 605 is also equipped with a vibration actuator as a drive source for moving the treatment table 603. As described above, since the vibration actuator does not use a magnet, it can be disposed in the vicinity of the magnetic field generating unit 601, and therefore, it is possible to increase the degree of freedom in designing the treatment table 603.

[0091] Here, an example is shown in which a needle is inserted into the bore 602 of the doughnut-shaped MRI diagnostic device 600, but the configuration of the MRI diagnostic device is not limited to the doughnut shape.

[0092] Although the present invention has been described in detail based on the preferred embodiments, the present invention is not limited to these specific embodiments, and various forms within the scope of the gist of the present invention are also included in the present invention. Furthermore, each of the above-mentioned embodiments shows only one embodiment of the present invention, and each embodiment can be appropriately combined. [Explanation of symbols]

[0093] 10,400 Vibration Actuator 20, 32 Vibration body (first member) 21, 32b Elastic body 22, 32a Piezoelectric element (electromechanical energy conversion element) 50 Power supply components 300, 310, 320, 330, 33, 360 contact body (second member) 301, 311, 321, 331, 341, 351 Main body (base) 302, 312, 322, 332, 342, 352 Spring part 303, 313, 323, 333, 343, 353 contact surface 304, 314, 324, 334, 344, 354 base material 305, 315, 325, 335, 345, 355 coating 307, 317, 327, 337, 347, 357 First inclined surface (inclined surface) 308, 328, 338, 358 Second inclined surface (inclined surface) 359 Contact parts

Claims

1. A first member having an elastic body and an electromechanical energy conversion element; a second member that is in contact with the elastic body and moves relative to the first member due to vibration generated in the electromechanical energy conversion element; The second member includes: a contact surface that contacts the first member and is nitrided; an inclined surface connected to the contact surface and inclined relative to the contact surface; A coating is formed on the inclined surface, A vibration actuator comprising an area on the back side of the coating, the area having a lower nitrogen content than the contact surface.

2. A first member having an elastic body and an electromechanical energy conversion element; a second member that is in contact with the elastic body and moves relative to the first member due to vibration generated in the electromechanical energy conversion element; The first member includes: a contact surface that contacts the second member and is nitrided; an inclined surface connected to the contact surface and inclined relative to the contact surface; A coating is formed on the inclined surface, A vibration actuator comprising an area on the back side of the coating, the area having a lower nitrogen content than the contact surface.

3. the second member has a base; 2. The vibration actuator according to claim 1, wherein the inclined surface is formed between the contact surface and the base portion.

4. The first member has a base, 3. The vibration actuator according to claim 2, wherein the inclined surface is formed between the contact surface and the base portion.

5. the vibration actuator includes a pressure member that brings the first member and the second member into pressure contact with each other, 5. The vibration actuator according to claim 3, wherein the first member or the second member has a spring portion extending from the base portion between the contact surface and the base portion in a direction intersecting the pressure direction applied by the pressure member.

6. the first member or the second member has a contact member that fits with the spring portion, The contact member is The contact surface; 6. The vibration actuator according to claim 5, further comprising the inclined surface.

7. 7. The vibration actuator according to claim 1, wherein an inclination angle of the inclined surface with respect to the contact surface is equal to or greater than 100 degrees and equal to or less than 175 degrees.

8. 7. The vibration actuator according to claim 1, wherein an inclination angle of the inclined surface with respect to the contact surface is equal to or greater than 5 degrees and equal to or less than 80 degrees.

9. 6. The vibration actuator according to claim 5, wherein the thickness of the coating is 1 [mu]m or more and 10% or less of the minimum thickness of the spring portion.

10. 10. The vibration actuator according to claim 1, wherein the contact surface and the inclined surface are made of an iron-based material.

11. 11. The vibration actuator according to claim 10, wherein the coating is made of a metal material other than the iron material.

12. 11. The vibration actuator according to claim 10, wherein the iron-based material is an austenitic stainless steel.

13. 12. The vibration actuator according to claim 11, wherein the metallic material other than the iron-based material is a material containing copper, nickel, tin, silver or chromium as a main component.

14. The base and The vibration actuator according to claim 1 , which is provided on the base; and a driven body that is moved relatively to the base by the vibration actuator.

15. The material, The vibration actuator according to claim 1 , which is provided on the member; and a driven body that is moved relatively to the member by the vibration actuator.

Images