Vibration actuator and electronic device

Abstract

To provide a vibration actuator with high wear resistance, which suppresses a deterioration in drive performance and the occurrence of an abnormal noise.SOLUTION: A vibration actuator includes: a vibrator having an annular elastic body and an electro-mechanical energy conversion element; and an annular contact body which contacts the elastic body. The vibrator and the contact body are moved relative to each other when the vibrator vibrates. The contact body includes: an annular base; an annular thin plate extending from the base toward the center axis of the ring of the base; an annular support provided at the end of the thin plate; and an annular friction member, a member different from the support, which is provided on the support to contact the elastic body. The base, the thin plate, and the support are integrally formed. The friction member, which is formed of a ferrous material, has a higher density than the thin plate. A weight ratio obtained by dividing the weight of the thin plate by the total weight of the friction member and the support is 0.5 to 1.5.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a so-called vibration actuator that frictionally drives a driven body by bringing a vibrating body into pressure contact with the driven body, and more particularly to the structure of a contact body of the vibration actuator. [Background technology]

[0002] A vibration actuator has a vibrating body composed of an electromechanical energy conversion element such as a piezoelectric element and an elastic body, and a contact body that is in pressure contact with the vibrating body. The vibration actuator is used as a vibration wave motor that moves the contact body relative to the vibration body by utilizing friction generated by the driving force of vibration excited in the vibrating body. One type of vibration actuator is a rotary vibration actuator. A lens is attached to the hollow part of the rotary vibration actuator, and the lens is moved for the autofocus or zoom function of a camera, or the rotary vibration actuator is used as a driving source for panning and tilting operations.

[0003] A rotary vibration actuator has a circular vibrating body and a circular contact body that is in pressurized contact with the vibrating body by a pressure member. The contact body can be divided into three parts: a contact part that contacts the vibrating body, a main ring part located on the outer diameter side of the contact body, and a spring part that connects the main ring part and the contact part. The main ring part and the spring part are generally molded as one piece from a single material using cutting processing or the like.

[0004] Patent Document 1 describes an example of a contact body in which the contact portion is made of a separate material, and cites a contact body in which a friction member made of resin or carbon fiber, which has a lower density than a moving body made of aluminum alloy or phosphor bronze, is joined by adhesive or the like as the contact portion.

[0005] However, in the technology described in Patent Document 1, the friction member made of small resin or carbon fiber was used, so the wear resistance of the contact portion was insufficient. In addition, according to the study by the inventors of the present application, it was found that if an iron-based material such as stainless steel is used for the friction member to improve the wear resistance, the friction member has a high density, so the weight increases, and there is a risk that the natural frequency of the spring portion will decrease. In this case, the frequency of the vibration excited in the vibrating body (hereinafter referred to as the driving frequency) and the natural frequency of the contact body become close to each other, and there is a problem that unintended vibration occurs in the contact body when driving the vibration type actuator, which reduces the driving performance and generates abnormal noise. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2000-245175 A Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the present invention provides a vibration actuator that has high wear resistance at the contact portion and suppresses the deterioration of driving performance and the generation of abnormal noise. [Means for solving the problem]

[0008] The vibration actuator of the present invention comprises: a vibrator having an annular elastic body and an electromechanical energy conversion element; a ring-shaped contact body that contacts the elastic body, A vibration actuator in which the vibrating body and the contact body move relatively to each other due to vibration of the vibrating body, The contact body is An annular base; an annular thin plate portion extending from the base toward a central axis of the ring of the base; An annular support portion provided at an end portion of the thin plate portion; an annular friction member that is provided on the support portion and comes into contact with the elastic body, the friction member being a separate member from the support portion; having the base portion, the thin plate portion, and the support portion are integrally formed, The friction member is made of an iron-based material, The density of the friction member is greater than the density of the thin plate portion, a weight ratio obtained by dividing the weight of the thin plate portion by the combined weight of the friction member and the support portion is 0.5 to 1.5; the law of nature, The annular friction member is an L-shaped member cut along a plane parallel to the rotation axis. It is characterized by the above. Effect of the Invention

[0009] According to the present invention, it is possible to increase the natural frequency of the contact body even if a high-density material such as an iron-based material is used for the friction member, and it is possible to provide a vibration actuator having high wear resistance in the contact area and suppressing deterioration of drive performance and generation of abnormal noise. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a vibration actuator according to a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view of a rotary vibration actuator according to a first embodiment of the present invention. [Diagram 3] 1 is a cross-sectional view of a contact body in a first embodiment of the present invention. [Figure 4] 3A to 3C are diagrams illustrating a configuration of a contact body in the first embodiment of the present invention. [Diagram 5] 1 is a graph illustrating a problem to be solved by the present invention. [Figure 6] 1 is a graph illustrating the effects of the present invention that the inventors have investigated. [Figure 7] 6 is a graph illustrating the effect when the shape of the rotating body is changed in the first embodiment of the present invention. [Figure 8] FIG. 13 is a diagram of a pan head device according to a third embodiment of the present invention. [Figure 9]4 is a graph showing the relationship between sliding radius and weight ratio in the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The vibration actuator of the present invention is a vibration actuator including a vibrator having a ring-shaped elastic body and an electromechanical energy conversion element, and a ring-shaped contact body in contact with the elastic body, and the vibrator and the contact body move relative to each other due to vibration of the vibrator. The contact body includes a ring-shaped base, a ring-shaped thin plate portion extending from the base toward the central axis of the ring of the base, The elastic body has an annular support portion provided at an end of the thin plate portion, and an annular friction member provided at the support portion and in contact with the elastic body, which is a separate member from the support portion. The base portion, the thin plate portion, and the support portion are integrally formed, and the friction member is made of an iron-based material. The density of the friction member is greater than that of the thin plate portion, and the weight ratio of the weight of the thin plate portion divided by the combined weight of the friction member and the support portion is 0.5 to 1.5.

[0012] The following detailed description will be given with reference to the drawings. EXAMPLES

[0013] FIG. 1 is a perspective view of a rotary vibration actuator in accordance with a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the rotary vibration actuator in accordance with the first embodiment of the present invention taken along a plane passing through the central axis of rotation and parallel to the axis.

[0014] In FIG. 2, a center line L1 is the rotation axis of the rotary vibration actuator, and the rotary vibration actuator includes a vibrating body 41 formed in a circular ring shape, a contact body 1 also formed in a circular ring shape, and a pressure mechanism 50.

[0015] A piezoelectric element 40, which is an electromechanical energy conversion element, is attached to the surface of the elastic body 4 facing the contact body 1 to form a vibrating body 41. The vibrating body 41 is fixed to the vibrating body support member 6 using screws.

[0016] The pressure mechanism 50 is composed of a pressure spring receiving member 5, a pressure spring receiving rubber 51, a pressure spring 52, and a pressure spring fixing portion 53. The vibrating body 41 and the contact body 1 are arranged concentrically with the shaft 7 as the central axis, and are in pressure contact with each other in the thrust direction of the shaft 7 by the pressure mechanism 50 fixed to the shaft 7. Specifically, the pressure spring 52, whose movement is restricted by the pressure spring fixing member 53 fixed to the shaft 7, presses the contact body 1 in the thrust direction via the vibration-damping rubber 9, the pressure spring receiving member 5, and the pressure spring receiving rubber 51, thereby bringing the contact body 1 and the vibrating body 41 into stable contact.

[0017] In this embodiment, a leaf spring is used as the pressure spring 52. The pressure spring fixing member 53 is fixed to the shaft 7 by a set screw (not shown) (internal screw, set screw). The shaft 7 is rotatably supported by the support member 6 that supports the vibrating body 41 via the rotary bearings 8a and 8b. In this embodiment, a ball bearing is used as the rotary bearing, but a sliding bearing or a thrust bearing may be used as long as the shaft 7 is rotatably supported by the vibrating body support member 6. This allows the contact body 1 to move stably in the circumferential direction relative to the vibrating body 41, centered on the rotation axis L1.

[0018] The vibration actuator of the present invention excites a driving vibration in the vibrating body 41 by applying a driving voltage, which is an AC voltage, to the piezoelectric element 40 through a power supply member (not shown). The driving vibration depends on the configuration of the piezoelectric element 41, but the piezoelectric element 40 is designed so that the excited driving vibration becomes an n-th order (n=7 in this embodiment) traveling wave that progresses in the circumferential direction of the vibrating body 41. Note that the n-th order driving vibration is a bending vibration with n waves in the circumferential direction of the vibrating body 41. The driving vibration generated in the piezoelectric element 41 drives the contact body 1 in the circumferential direction around the shaft 7 by the traveling wave generated in the contact portion of the vibrating body 41.

[0019] 3 is a diagram for explaining the configuration of the contact body 1 in the first embodiment of the present invention. The contact body 1 is made up of a rotating body 2 and a friction member 3 which is a portion that comes into contact with the vibrating body 41. Furthermore, the rotating body 2 is made up of a main body portion 2a, a thin plate portion 2b, and a support portion 2c that supports the friction member 3, and the friction member 3 is fixed to the support portion 2c by a means such as adhesion. In this embodiment, the friction member 3 is made larger than the support portion 2c so that the contact state between the friction member 3 and the vibrating body 41 is not affected even if the adhesive that fixes the friction member 3 protrudes from the adhesive portion.

[0020] FIG. 4 shows an exploded view of the contact body 1 in the first embodiment of the present invention. As shown in FIG. 4, the rotating body 2 is integrally formed with a main body portion 2a, a thin plate portion 2b, and a support portion 2c. The thin plate portion 2b has a length L and a thickness t. The thin plate portion 2b of the rotating body 2 acts as a contact spring. For this reason, it is preferable that the thin plate portion 2b, which is a contact spring, is made of a material with a low Young's modulus, such as an aluminum alloy, which can suppress variation in the spring constant even if there is a processing error. In this embodiment, the rotating body 2 is made of an aluminum alloy.

[0021] Here, the definition of the spring constant in the present invention will be explained. As described above, the contact body 1 and the vibrating body 41 are in contact while being pressurized by the pressure spring 52, and the thin plate portion 2b of the contact body 1 has low rigidity and is in a state of being largely elastically deformed. The relationship between the force applied by the pressure spring 52 at this time and the displacement of the thin plate portion 2b in the pressure direction is defined as the spring constant in the present invention. By appropriately managing this spring constant, it is possible to make the contact state between the contact body 1 and the vibrating body 41 during driving appropriate.

[0022] The friction member 3 has a substantially L-shaped surface when cut along a plane parallel to the rotation axis. Therefore, two different surfaces can be used as adhesive surfaces, improving adhesive strength. Since the friction member 3 is in frictional contact with the vibrating body 41, it is desirable to use an iron-based material such as steel, which has high wear resistance. In this embodiment, stainless steel is used as the material for the friction member 3.

[0023] The processing method of the rotating body 2 and the friction member 3 will now be described. The friction member 3 is preferably made of a material with high wear resistance, and in this embodiment, it can be manufactured by pressing and hardening using a stainless steel material. On the other hand, the rotating body 2 is preferably made of a free-cutting material that can be processed with high precision, and is manufactured by cutting using an aluminum alloy that is more free-cutting than the friction material 3. In other words, the material of the contact body is an aluminum alloy, and the material of the friction material may be stainless steel.

[0024] The rotating body 2 may be surface-treated, for example, may be anodized. The processing method of the friction member 3 is not limited to press processing, and may be laser processing, electric discharge processing, cutting processing, etching processing, etc. In addition, nitriding, carburizing, etc. may be performed as heat treatment, and hardening treatment such as plating may be performed other than heat treatment.

[0025] Here, the problem with the structure of the contact body 1 of this embodiment will be explained. Figures 5(a) and (b) show graphs of the relationship between the length L of the thin plate portion 2b and the natural frequency of the vibration mode in which the thin plate portion 2b deforms. Figure 5(a) shows the natural frequency of the thin plate portion 2b in a configuration in which the friction member is a separate member from the contact body, and Figure 5(b) shows the natural frequency of the thin plate portion 2b in a configuration in which the contact body and the friction member are integrally formed.

[0026] In the present invention, the natural frequency refers to the lowest frequency of the vibration modes in which the thin plate portion 2b deforms when modal analysis is performed. Specifically, the analysis is performed with the upper surface of the main ring portion 2a of the rotor 2, i.e., the contact surface with the vibration-damping rubber 9, fixed as an analysis condition, to extract the vibration mode in which the thin plate portion 2b deforms.

[0027] The spring constant of each plot connected by a line in each graph is constant, and the thickness t of the thin plate portion 2b shown on the second axis on the right side of the graph increases as the length L of the thin plate portion increases. In addition, the first axis on the left side in Figs. 5(a) and (b) represents the natural frequency, with the lower limit being 0 and the upper limit being Y, and the range of the first axis being the same. The natural frequency of the thin plate portion 2b in the configuration in which the friction member is a separate member from the contact body shown in Fig. 5(a) is represented, and is lower than the natural frequency of the thin plate portion 2b in the configuration in which the contact body and the friction member are integrally formed shown in Fig. 5(b). In other words, the natural frequency of the thin plate portion 2b is reduced by fixing the friction member 3 made of an iron-based material to the tip of the thin plate portion 2b.

[0028] In order to suppress the deterioration of drive performance and abnormal noise, it is desirable to increase the natural frequency, and in a configuration in which the contact body and the friction member are integrally formed, it is effective to make the thin plate portion 2b smaller, that is, to make the thin plate portion 2b thinner and shorter (reducing L and t). The relationship between the radial length L of the thin plate portion 2b and the thickness t of the thin plate portion 2b in this case is shown as a graph with a dashed dotted line in Figure 5(b). The natural frequency is shown as a graph with a solid line, and the thinner and shorter the thin plate portion 2b, the higher the natural frequency.

[0029] However, in a configuration in which friction member 3 is attached as a separate member to the tip of thin plate portion 2b as shown in FIG. 5(a), it was found that there is an inflection point where the natural frequency starts to decrease when thin plate portion 2b is made thinner and shorter.

[0030] As described above, in the contact body 1 shown in FIG. 3, the friction member 3 made of stainless steel, which has a higher material density than an aluminum alloy, is attached to the support portion 2c provided at the tip of the thin plate portion 2b, which poses the problem that the natural frequency of the thin plate portion 2b is lower than when the friction member is not a separate member and the rotor is formed solely from an aluminum alloy.

[0031] As described above, in order to increase the natural frequency, it is common to make the thin plate portion 2b thin and short, i.e., to make it smaller. However, the inventors' study revealed that if the thin plate portion 2b is made too small when the friction member 3 is attached, the natural frequency will decrease. This is because the weight of the support portion 2c and the friction member 3 provided at the tip of the thin plate portion 2b is relatively larger than that of the thin plate portion 2b, and therefore the influence of the support portion 2c and the friction member 3 on the natural frequency is large. For this reason, in order to maximize the natural frequency in a configuration in which the friction member 3 is provided at the tip of the rotating body 2 as in the first embodiment of the present invention, the relationship between the weight of the thin plate portion 2b and the combined weight of the support portion 2c and the friction member 3 must satisfy a specific condition.

[0032] The inventors have therefore investigated the relationship between the weight ratio X and the natural frequency Fr, and the results are shown in Figure 6. The horizontal axis of the graph is the weight ratio X, which is the ratio between the weight of the thin plate portion 2b of the rotor 2 and the combined weight of the support portion 2c and the friction member 3 when the thickness and radial length of the thin plate portion 2b are changed so that the spring constant of the thin plate portion 2b is constant. In other words, the weight ratio X is

[0033]

number

[0034] The vertical axis of the graph is the natural frequency Fr for each X. As described above, the natural frequency Fr is the frequency of the lowest vibration mode among the vibration modes in which the thin plate portion 2b deforms when the modal analysis is performed. In the shape of this embodiment, the natural frequency Fr is maximum when X ≈ 0.9, as shown in FIG. 6.

[0035] Figure 7 shows the results of a similar analysis performed under multiple conditions with different spring constants. The spring constants were divided into four stages for analysis, and were defined as very soft, soft, medium, and hard from the lowest spring constant, with the spring constant of very soft differing by approximately 30 times from that of hard. The spring constant in Figure 6 is medium, which is approximately 10 times that of very soft. Since the natural frequency also changes when the spring constant is changed, in Figure 7 the maximum natural frequency for the spring constants plotted on the vertical axis is set to 1, and the natural frequency ratio is Ra. Figure 7 shows that the natural frequency Fr is maximized when X = 0.8 to 0.9, regardless of the spring constant. In other words, even if the spring constant is changed, it is possible to maximize the natural frequency Fr if the weight ratio is in the range of X = 0.8 to 0.9.

[0036] Furthermore, by suppressing the variation in the natural frequency when the shape of the parts is changed due to the effect of processing errors of the rotor 2 and the friction material 3, it is possible to provide a rotary vibration actuator with stable performance. As shown in Fig. 7, when the weight ratio X = 0.5 to 1.5, the natural frequency can be set to 0.95 (= 95%) or more of the maximum natural frequency. Furthermore, when the weight ratio X = 0.65 to 1.15, the natural frequency can be set to 0.98 (= 98%) or more of the maximum natural frequency. In other words, when the weight ratio X = 0.65 to 1.15, the variation in the natural frequency is further suppressed, which is preferable.

[0037] FIG. 9 shows a graph of the change in weight ratio when the inner diameter of the friction member 3 is changed while the cross-sectional shapes of the friction member 3 and the rotating body 2 are kept constant. The horizontal axis represents the inner diameter of the friction member 3. The vertical axis represents the change in weight ratio X. FIG. 9 shows the change in weight ratio X relative to the inner diameter of the friction member 3, and does not seek the optimal solution for weight ratio X. From FIG. 9, it can be seen that the weight ratio X is almost constant when the inner diameter of the friction member 3 is 20 mm or more, and that the weight ratio X is determined from the cross-sectional shapes of the thin plate portion 2b, the support portion 2c, and the friction member 3 as long as the inner diameter is a predetermined value or more. Note that the weight ratio X at this time is not necessarily the value when the natural frequency is maximized.

[0038] Here, we will explain a method for defining the weight ratio X without taking into account the weights of the thin plate portion 2b, the support portion 2c, and the friction member 3. If the cross-sectional area of ​​the thin plate portion 2b is S1, the cross-sectional area of ​​the support portion 2c is S2, the cross-sectional area of ​​the friction member 3 is S3, the density of the rotating body 2 is D1, and the density of the friction member 3 is D2, then the weight ratio X can be expressed as X = S1 x D1 / (S2 x D1 + S3 x D2).

[0039] In order to suppress the decrease in the natural frequency in a configuration in which the friction member is positioned and fixed to the contact body to form the contact portion, it is possible to reduce the size and weight of the friction member. However, if the friction member is made smaller, when an adhesive is used to fix the friction member to the contact body, the adhesive area becomes smaller, and there is a risk of the adhesive strength decreasing. Therefore, it is necessary to make the friction member larger to some extent in order to ensure the adhesive strength.

[0040] In order to ensure the adhesive strength, it is desirable that the contact area between the friction member 3 and the support portion 2b is large. In addition, when the friction member 3 is fixed to the support portion 2b using an adhesive, if the adhesive protrudes from the friction member 3 into the area where the friction member 3 contacts the vibration body 41, it may hinder the drive. Therefore, it is desirable that the friction member 3 is longer in the radial direction than the support portion 2c. The dimensions of each part at this time will be explained using FIG. 4. In this embodiment, it is preferable that the radial length c of the adhesive surface side of the friction member 3 is 1.2 times or more larger than the radial length b of the support portion 2c (c / b≧1.2). The extension part of the friction member 3 extending from the support portion 2c can be used as an adhesive reservoir. In addition, if the radial length c of the friction member 3 is too long compared to the radial length b of the support portion 2c, the displacement of the part where the friction member 3 protrudes radially from the support portion 2c when pressure is applied may become large, and the contact state may change. Therefore, it is desirable that the radial length c of the friction member 3 is twice or less than the radial length b of the support portion 2c (c / b≦2). For example, if the radial length b of the support portion 2c is 0.3 mm, the radial length c of the friction member 3 is 0.36 mm or more and 0.6 mm or less.

[0041] That is, the width of the radial area of ​​the friction member that comes into contact with the support portion is 1.2 times or more and 2 times or less than the width of the radial area of ​​the support portion.

[0042] Similarly, in order to ensure the adhesive strength between the friction member 3 and the support portion 2c, the area where the friction member 3 and the support portion 2c contact in the axial direction is increased. At the same time, in order to suppress the influence of the adhesive overflowing, it is necessary to prevent the adhesive from spreading to the contact area between the friction member 3 and the vibration body 41. For this purpose, it is necessary to make the height h2 of the adhesive surface side of the friction member 3 larger than the height h1 of the support portion 2c, and to provide an adhesive pool on the surface of the support portion 2c opposite to the surface where the contact body 1 and the vibration body 41 contact. In this embodiment, the height h2 of the adhesive surface side of the friction member 3 is 1.4 times the height h1 of the support portion 2c (h2 / h1=1.4). The difference between the height h2 of the friction member 3 and the height h1 of the support portion 2c should be 1.2 times or more in order to act as an adhesive pool, and it is desirable that h2 / h1 be 1.8 times or less because the natural frequency decreases if the friction member 3 is too large. For example, if the height h1 of the support portion 2c is 0.5 mm, the height h2 of the friction material 3 is 0.6 mm or more and 0.9 mm or less. EXAMPLES

[0043] As a second embodiment, the configuration of a pan head device (rotating device) will be described as an example of a device equipped with at least two vibration type actuators of the present invention.

[0044] FIG. 8(a) is a front view of the pan head device 200 in this embodiment, and FIG. 8(b) is a side view of the pan head device 200 in this embodiment.

[0045] The camera platform 200 has a head section 210, a base section 220, an L-angle 230, and an imaging device 240. Inside the head section 210, two vibration type actuators of the present invention are disposed.

[0046] The output section of the vibration actuator 280 for panning is connected to the base member 220 , and the head section 210 is panned relative to the base section 220 by the rotational drive of the vibration actuator 280 .

[0047] The output section of the vibration actuator 270 for tilting is connected to the L-angle 230 , and the rotational drive of the vibration actuator 270 tilts the L-angle 230 relative to the head section 210 .

[0048] The imaging device 240 attached to the L-angle 230 is a camera for taking moving and still images, and is capable of panning and tilting by driving two vibration type actuators while taking pictures.

[0049] As described above, the vibration actuator of the present invention can be used as a drive source for a camera-head device. [Industrial Applicability]

[0050] The present invention can be used in a vibration actuator such as an ultrasonic motor. It may also be configured as an optical device having an optical element and the above vibration actuator in a driving section. It may also be used as an electronic device having a substrate and the above vibration actuator on the substrate. [Explanation of symbols]

[0051] 1 contact body 2 Rotating body 2a Main body 2b Thin plate part 2c Support part 3 Friction materials 4 Elastic Body 5 Pressure spring support member 6. Vibration body support member 7 Shaft 8a, 8b Rotary bearing 9. Vibration-damping rubber 40 Piezoelectric element 41 Vibration Body 50 Pressure Mechanism 51 Pressure spring support rubber 52 Pressure spring 53 Pressure spring fixing part 200 Panhead device 210 Head 220 Base 230 L angle 240 Imaging Device 270 Vibration Actuator 280 Vibration Actuator

Claims

1. A vibrating body having an annular elastic body and an electromechanical energy conversion element; a ring-shaped contact body that contacts the elastic body, A vibration actuator in which the vibrating body and the contact body move relatively to each other due to vibration of the vibrating body, The contact body is An annular base; an annular thin plate portion extending from the base toward a central axis of the ring of the base; An annular support portion provided at an end of the thin plate portion; an annular friction member that is provided on the support portion and comes into contact with the elastic body, the friction member being a separate member from the support portion; having the base portion, the thin plate portion, and the support portion are integrally formed, The friction member is made of an iron-based material, The density of the friction member is greater than the density of the thin plate portion, a weight ratio obtained by dividing the weight of the friction member and the support portion by the weight of the thin plate portion is 0.5 to 1.5; 4. A vibration actuator comprising: a first friction member and a second friction member;

2. 2. The vibration actuator according to claim 1, wherein the base, the thin plate and the support are made of an aluminum alloy, and the friction member is made of stainless steel.

3. 3. The vibration actuator according to claim 1, wherein the weight ratio is 0.65 to 1.

15.

4. 4. The vibration actuator according to claim 1, wherein the radial area width of the friction member in contact with the support portion is 1.2 times or more and 2 times or less than the radial area width of the support portion.

5. 5. The vibration actuator according to claim 1, wherein the axial area width of the friction member in contact with the support portion is 1.2 times or more and 1.8 times or less than the axial area width of the support portion.

6. 6. The vibration actuator according to claim 1, wherein the friction member has an inner diameter of 20 mm or more.

7. The cross-sectional area of ​​the thin plate portion cut by a plane passing through the central axis of rotation of the vibration actuator and parallel to the axial direction is S1, the cross-sectional area of ​​the support portion cut by the plane is S2, and the cross-sectional area of ​​the friction member cut by the plane is S3. When the density of the contact body is D1 and the density of the friction member is D2, the weight ratio X is given by X=S1×D1 / (S2×D1+S3×D2) 7. The vibration actuator according to claim 1, wherein the vibration actuator is represented by the formula:

8. An optical device comprising an optical element and the vibration actuator according to claim 1 in a drive section.

9. An electronic device comprising: a substrate; and the vibration actuator according to claim 1 on the substrate.

10. An imaging device comprising, in a drive section, the vibration type actuator according to claim 1 .

Images