Vibrating actuator, optical device, and electronic device

Abstract

The invention provides a vibrating actuator, an optical device, and an electronic device. The vibrating actuator includes a vibrating body and a contact body in contact with an elastic body. The elastic body comprises a flat plate part and a protruding part. The vibrating actuator further includes, as part of the adhesive, a first adhesive layer between the electrical-mechanical energy conversion element and the flat plate portion, and a second adhesive layer adjacent to the first adhesive layer, the second adhesive layer being disposed between the electrical-mechanical energy conversion element and the flat plate portion. A thickness of the second adhesive layer is greater than a thickness of the first adhesive layer and increases toward the protrusion.

Description

Technical Field

[0001] The present invention relates to a vibration actuator, an optical device, and an electronic device including the vibration actuator. Background Art

[0002] Japanese Patent No. 5930595 discusses a vibration wave motor using an electric energy-mechanical energy conversion element such as a piezoelectric element as a vibration generation source. The vibration wave motor includes a vibrator and a contact body. The vibrator includes a plate-type elastic body and a piezoelectric element fixed to the reverse surface of the elastic body. The elastic body has an upper surface on which two protrusions are arranged. The contact body is in pressure contact with the protrusions.

[0003] In this vibration wave motor, a predetermined AC voltage is applied to the electric energy-mechanical energy conversion element.

[0004] In this way, two bending vibrations (standing waves) are excited to generate elliptical or circular motion at the end of the protrusion (for example, including the contact surface of each protrusion arranged in pressure contact with the contact part). The motion occurs in a plane including the direction connecting the two protrusions (for example, the direction running through the two protrusions) and the protruding direction of the protrusion. The contact body in pressure contact with the protrusion receives the friction driving force (thrust) from the two protrusions, so that the vibrator and the contact body can move relative to each other in the direction connecting the two protrusions.

[0005] On the other hand, in order to reduce the size of electronic devices, actuators such as vibration wave motors are required to have smaller sizes and drive larger objects, which means high-power densification in actuators.

[0006] With the trend toward high-power densification in vibration wave motors, there is a problem that an adhesive generally used to bond a piezoelectric element and an elastomer may peel off due to high stress applied to the vibrator. Summary of the invention

[0007] In view of this problem, the present invention is directed to providing a vibration wave motor having high output power and bonding reliability and an electronic device including the vibration wave motor.

[0008] According to one aspect of the present invention, a vibration actuator is provided, the vibration actuator comprising: a vibration body, the vibration body comprising an electric energy-mechanical energy conversion element and an elastic body bonded to each other via an adhesive; and a contact body, the contact body being in contact with the elastic body. The vibration body and the contact body are configured to move relative to each other through the vibration of the vibration body. The elastic body comprises: a flat plate portion, the flat plate portion being bonded to the electric energy-mechanical energy conversion element via the adhesive; and a protrusion, the protrusion extending to the flat plate portion and protruding from the flat plate portion. As a part of the adhesive, between the electric energy-mechanical energy conversion element and the flat plate portion, the vibration actuator further comprises: a first adhesive layer; and a second adhesive layer, the second adhesive layer being adjacent to the first adhesive layer, the thickness of the second adhesive layer being greater than the thickness of the first adhesive layer and increasing toward the protrusion.

[0009] Further features of the present invention will become apparent from the following description of examples with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is an exploded perspective view illustrating a vibration wave motor in a first exemplary embodiment of the present invention.

[0011] Figure 2 is a perspective view illustrating the assembly of the vibration wave motor in the first exemplary embodiment of the present invention.

[0012] Figure 3 is a perspective view for describing vibration modes in the first exemplary embodiment of the present invention.

[0013] Figure 4A is a top view of the vibrator in the first exemplary embodiment of the present invention. Figure 4B is a cross-sectional view of a vibrator in a first exemplary embodiment of the present invention. Figure 4C It is an enlarged cross-sectional view showing the vicinity of the rising portion of the protrusion. Figure 4D This is an enlarged view showing the vicinity of the edge of the flat plate portion.

[0014] Figure 5 is a diagram illustrating each adhesive layer region in the vibrator in the first exemplary embodiment of the present invention.

[0015] Figure 6 : is a graph illustrating shear stress applied to the bonding surface of the elastic body in each vibration mode in the first exemplary embodiment of the present invention.

[0016] Fig. 7A : is a top view illustrating a schematic configuration of an image pickup apparatus (electronic device) using a vibration wave motor in a second exemplary embodiment of the present invention. Figure 7B: is a block diagram illustrating a schematic configuration of an image pickup apparatus (electronic device) using a vibration wave motor in a second exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0017] Will refer to Figures 1 to 6 , taking the application of the present invention to a linear vibration wave motor as an example, the first exemplary embodiment is described in detail. First, Figure 1 is an exploded perspective view of the vibration wave motor 1 in the first exemplary embodiment of the present invention. Figure 2 : is a perspective view of the assembly of the vibration wave motor 1. The driving direction of the slider 9 serving as the contact body (for example, the direction of the relative movement of the vibrator 2 and the slider 9 to be described below) is the "X direction" (or simply "X"). The direction in which the slider 9 is in pressure contact with the vibrator 2 (for example, the pressing direction) is the "Z direction" (or simply "Z"). In addition, the direction orthogonal to the X direction and the Z direction is defined as the "Y direction".

[0018] (or "Y" for short).

[0019] The piezoelectric element 4 as an electric energy-mechanical energy conversion element is fixed to the elastic body 3 via an adhesive, and further, the flexible printed board 5 is electrically connected to the piezoelectric element 4 on the surface opposite to the surface on which the elastic body 3 is provided. The elastic body 3, the piezoelectric element 4, and the flexible printed board 5 constitute the vibrator 2. The flexible printed board 5 is fixed to the piezoelectric element 4 using an anisotropic conductive glue or an anisotropic conductive film that can conduct electricity only in the Z direction. The elastic body 3 is formed of two protrusions 3a protruding on the opposite sides of the piezoelectric element 4 and a flat plate portion 3b in the shape of a flat plate.

[0020] Lead zirconate titanate is used for the piezoelectric element 4. Alternatively, the piezoelectric element 4 may be mainly composed of a piezoelectric material that does not contain lead, such as barium titanate or sodium bismuth titanate, i.e., a piezoelectric material having a lead content of 1000 ppm or less. Electrode patterns 4a are formed on both surfaces of the piezoelectric element 4, and power is supplied from the flexible printed board 5 via the electrode patterns 4a.

[0021] A pressure member 6 that presses and supports the vibrator 2 is provided below the vibrator 2. Pressure is applied to the pressure member 6 by a pressure spring 7, and a reaction force is received by a base 8 that serves as a pressure receiving member. A conical coil spring is used as the pressure spring 7 to reduce the size of the vibration wave motor 1 in the Z direction. The coil shape is illustrated in a simplified manner.

[0022] A slider 9 is provided above the vibrator 2 and is in pressure contact with the elastic body 3. The slider 9 is fixed to the slider bracket 10 and is driven as a whole with the slider bracket 10 in the X direction. Rubber may be provided between the slider 9 and the slider bracket 10 to reduce vibration. The slider 9 is composed of metal, ceramic, resin or a composite material thereof, all of which have high wear resistance. Specifically, a material obtained by nitriding stainless steel (such as SUS420J2) has advantages in wear resistance and mass production.

[0023] Three balls 11 are inserted between the slider bracket 10 and three pairs of upper and lower rails provided in the ball rail 12 fixed to the base 8, so that the slider 9 and the slider bracket 10 can move relative to other components in the X direction. An output transmission part having a desired shape attached to the slider bracket 10 transmits the output to the outside. Although an example in which the vibrator 2 is fixed and the slider 9 is moved is described, the slider 9 may be fixed and the vibrator 2 may be moved.

[0024] Then, refer to Figure 3 Described is the vibration mode excited by vibrator 2. In the present exemplary embodiment, two AC voltages of different phases are applied to piezoelectric element 4 through flexible printed board 5, two out-of-plane bending vibrations are excited in different phases in vibrator 2, and vibration combining the two vibrations is generated.

[0025] Mode A, which is the first vibration mode, is a primary out-of-plane bending vibration mode in which two nodes appear in parallel in the X direction, which is the length direction of the vibrator 2. In mode A, each protrusion 3a is located at a position where the vibration amplitude reaches a maximum in the Z direction, that is, at an antinode position, and the vibration in mode A causes each of the two protrusions 3a to shift in the Z direction, which is the pressure direction. Mode B, which is the second vibration mode, is a secondary out-of-plane bending vibration mode in which three nodes appear approximately in parallel in the Y direction, which is the width direction of the vibrator 2. In mode B, each protrusion 3a is located at a position where the vibration amplitude reaches a minimum in the Z direction, that is, at a node position, and the vibration in mode B causes each of the two protrusions 3a to shift in the X direction.

[0026] By combining the vibrations in mode A and mode B, the two protrusions 3a generate elliptical motion or circular motion in the ZX plane. The slider 9 is brought into pressure contact with the two protrusions 3a to generate friction in the X direction, thereby generating a driving force (thrust) for relatively moving the vibrator 2 and the slider 9. In the present exemplary embodiment, the vibrator 2 is held by the method described below so as to drive the slider 9 in the X direction.

[0027] In order to effectively drive the vibration wave motor 1, it is necessary to apply pressure to the vibrator 2 without suppressing the vibration (displacement) in the two vibration modes excited by the vibrator 2. To achieve this goal, it is desirable to support the vicinity of the nodes in the two vibration modes. In view of this, two protrusions 6a are provided on the pressure member 6 to pressurize and hold the nodes common to the two vibration modes, thereby more effectively applying pressure to the vibrator 2.

[0028] In addition, the protrusion 6a also plays a role of holding the vibrator 2 in the X direction and the Y direction. In the present exemplary embodiment, the flexible printed board 5 and the protrusion 6a are in contact with each other in the vibrator 2, and the pressure and the friction coefficient are adjusted so that the maximum static friction force between the flexible printed board 5 and the protrusion 6a is always greater than the thrust generated in the slider 9. That is, during the driving period of the vibration wave motor 1, the vibrator 2 does not move relative to the pressure member 6.

[0029] At the same time, the pressure member 6 is provided with four loosely embedded parts 6b (which are loosely adapted to the outer peripheral surface of the vibrator 2) that movably support the outer peripheral surface of the vibrator 2. These loosely embedded parts 6b play a role of positioning when the vibrator 2 is assembled and play a role of stopper when some external force acts on the slider 9.

[0030] In addition, the loosely fitted portion 6b may contact the vibrator 2 at two positions respectively different from the positions of the vibration nodes on the outer peripheral surface of the vibrator 2. However, as described above, the maximum static friction force between the flexible printed board 5 and the protrusion 6a is greater than the thrust generated in the slider 9, so the forces in the X direction and the Y direction do not act on the contact portion between each loosely fitted portion 6b and the vibrator 2. In view of this, the loss here can be ignored and no problem related to the drive will occur.

[0031] Since the protrusion 6a of the pressure member 6 is in direct contact with each other near the node of the vibrator 2 and the loose embedded portion 6b is in direct contact with each other on the peripheral surface of the vibrator 2, the material of the pressure member 6 is ideally a resin with high vibration isolation performance to prevent noise. For the above reasons, each protrusion 6a ideally has a larger friction coefficient to increase the force of holding the vibrator 2. At the same time, each loose embedded portion 6b ideally has a smaller friction coefficient to reduce the friction loss between each loose embedded portion 6b and the vibrator 2. For the above reasons, the protrusion 6a can also be coated with a coating for increasing the friction coefficient and the loose embedded portion 6b can be coated with a coating for reducing the friction coefficient. In addition, different components with appropriate friction coefficients can also be used by adhesive bonding or press fitting.

[0032] Then, refer to Figures 4A to 4D The details of the vibrator 2 are described. Figure 4A It is a top view of the vibrator 2. Figure 4B It is along Figure 4A AA line cut-off view shown in FIG. Each protrusion 3a formed on the elastic body 3 has a hollow shape and has elasticity (flexibility) in the pressure direction. This elasticity enables smooth contact between the vibrator 2 and the slider 9, thereby preventing noise.

[0033] Figure 4C It is a graphic Figure 4B An enlarged view of part B is shown in FIG. Figure 4D It is a graphic Figure 4B An enlarged view of portion C shown in FIG. An adhesive 13 is present between the flat plate portion 3b of the elastomer 3 and the piezoelectric element 4. In some cases, a too thick adhesive layer may weaken the vibration of the vibrator 2. In other cases, a too thin adhesive layer may reduce the bonding strength. Therefore, the thickness of a portion of the adhesive layer, that is, the thickness of the first adhesive layer 13a that occupies the main part of the adhesive layer, is ideally between 0 μm and 3 μm. Here, a thickness of 0 μm means that the elastomer 3 and the piezoelectric element 4 are in contact with each other. Due to tiny irregularities, undulations, and warping on the surface, the adhesive layer has a certain degree of distribution in thickness.

[0034] Figure 6 The figure shows the calculation results of the shear stress on the bonding surface of the elastic body 3 in the simulation mode A and B. Figure 6 In the calculation, each component is divided into a grid and the grids at locations where the shear stress is relatively high are filled with black. Of course, the shear stress is calculated by the piezoelectric element 4 included, but for simplicity, Figure 6 The piezoelectric element 4 is not shown in the figure. Figure 6 It can be understood that the shear stress is high around the root of each protrusion 3a and around the edge of each rectangular portion.

[0035] In order to relax the shear stress around each protrusion 3a, a second adhesive layer 13b is provided. The second adhesive layer 13b is adjacent to the first adhesive layer 13a, and its thickness gradually increases toward each protrusion 3a. The thickness of the second adhesive layer 13b is between 3μm and 10μm. By making the thickness of the second adhesive layer 13b greater than the thickness of the first adhesive layer 13a, the stress acting on the bonding layer can be relaxed. In addition, the thickness of the second adhesive layer 13b gradually increases to prevent local stress concentration. In some cases, in the radial direction of the second adhesive layer 13b, a length as a length (L2) that is too short will reduce the influence of stress relaxation, while a length that is too long will weaken vibration. Therefore, the thickness of the second adhesive layer 13b is ideally between 100μm and 400μm.

[0036] By appropriately defining the length in the radial direction of the protrusion 3a on the second adhesive layer 13b in the section between the end of the first adhesive layer 13a and the inflection point of the curved portion in this way, a more significant effect is expected.

[0037] The second adhesive layer 13 b is adjacent to the bent portion at the root of each protrusion 3 a , but the second adhesive layer 13 b and the bent portion are distinguished from each other at an inflection point.

[0038] like Figure 4C The maximum thickness of the second adhesive layer 13b shown in the example is t2. Figure 4C At the inflection point of the curved portion shown in , the line indicating the upper end of the maximum thickness t2 and the line indicating the right end of the length (L2) intersect each other.

[0039] The cross section of the bonding surface of the elastic body 3 within the second adhesive layer 13 b differs from the curved portion at the root of the protrusion 3 a in terms of different curvature or linear shape.

[0040] In addition, Figure 4C Similar to the configuration shown in , the following configuration may be adopted: wherein, in addition to the first adhesive layer 13a and the second adhesive layer 13b, an adhesive pool is provided adjacent to the second adhesive layer 13b and formed by extending the inflection point of the bent portion further toward the protruding portion 3a. The adhesive pool provided adjacent to the second adhesive layer 13b that is not on the first adhesive layer 13a side provides a robust vibrating body, ensuring a higher desired stress relaxation effect of the second adhesive layer 13b.

[0041] On the contrary, Figure 4D As shown in , in order to relax the stress around the edge portion of the piezoelectric element 4, a third adhesive layer 13c is provided. The third adhesive layer 13c is adjacent to the first adhesive layer 13a, and its thickness gradually increases toward the edge of the flat plate portion 3b. The thickness of the third adhesive layer 13c is between 3μm and 10μm. The thickness of the third adhesive layer 13c is greater than the thickness of the first adhesive layer 13a, which can relax the stress acting on the bonding layer. In addition, the thickness of the third adhesive layer 13c gradually increases to prevent local stress concentration. In the radial direction of the third adhesive layer 13c, if the length (L3) is too short, the stress relaxation effect will be reduced, while if the length (L3) is too long, the vibration will be weakened. Ideally, the thickness of the third adhesive layer 13c is between 100μm and 400μm. Figure 5 The distribution of each adhesive layer is shown and Figure 6 Compared with the case in FIG. 1 , it can be understood that the portion where a relatively high stress is applied is covered with the second adhesive layer 13 b and the third adhesive layer 13 c.

[0042] To provide the second adhesive layer 13b and the third adhesive layer 13c in this manner, the elastic body 3 or the piezoelectric element 4 is processed into a non-planar shape as described above. However, since the piezoelectric element 4 made of ceramic has poor processability, it is more advantageous to process the elastic body 3 into a non-planar shape. The elastic body 3 can be manufactured by stamping, forging, sintering, cutting or other processing, but the stamping method is optimal in terms of cost and dimensional accuracy.

[0043] At the same time, in order to ensure the height of the protrusion 3a, there is a case where flattening is performed and the volume of the flattened portion flows to the protrusion 3a. In this case, an impact line is formed around the protrusion 3a on the surface to be bonded, reducing the flatness, so that cutting processing such as grinding is required after stamping. In this exemplary embodiment, since grinding changes the non-planar shape, the protrusion 3a is formed by adjusting the height of the protrusion 3a instead of flattening. That is, before and after the protrusion 3a is formed, the internal volume of the protrusion 3a starting from its rising part is equal. Since there is no flattening, the flatness of the surface to be bonded can be maintained, thereby eliminating the need for processing such as grinding.

[0044] As another effect brought about by the absence of specific processing such as grinding, the plate thickness of the flat plate portion 3b is stabilized and the plate thickness difference (i.e., the difference between the maximum and minimum values ​​of the thickness of the flat plate portion 3b) is 10 μm or less, thereby stabilizing the resonance frequency of the vibrator 2 in mode A and mode B.

[0045] The elastomer 3 is ideally made of a material with low vibration attenuation such as metal. A particularly ideal material is martensitic stainless steel, which is suitable because martensitic stainless steel has particularly low attenuation and because the hardness of martensitic stainless steel can be increased by quenching after specific processing, thereby increasing the wear resistance of martensitic stainless steel. In the present exemplary embodiment as described above, in the absence of specific processing such as grinding, the surface to be bonded of the elastomer 3 is formed only by quenching (i.e., by plastic forming) after rolling. Although there are various types of surfaces obtained by rolling, the appropriate surface roughness selected makes the surface have sufficient bonding strength. The surface roughness Ra is ideally between 0.025 μm and 0.2 μm. This is because a certain degree of surface roughness will increase the anchoring effect and surface area, thereby increasing the bonding strength of the surface.

[0046] A second exemplary embodiment will now be described. For example, a vibration wave motor can be used to drive a lens of an image pickup device (optical device). Next, an example of an image pickup device that uses a vibration wave motor to drive a lens arranged in a lens barrel will be described.

[0047] Fig. 7A7 is a top view illustrating a schematic configuration of an image pickup device 700. The image pickup device 700 includes a camera body 730, and the camera body 730 is provided with an image pickup element 710 and a power button 720. The image pickup device 700 also includes a lens barrel 740, and the lens barrel 740 includes a first lens group (not shown), a second lens group 320, a third lens group (not shown), a fourth lens group 340, and vibration-type drive devices 620 and 640. The lens barrel 740 can be replaced as a replaceable lens. The lens barrel 740 suitable for a subject to be imaged can be attached to the camera body 730. In the image pickup device 700, the second lens group 320 and the fourth lens group 340 are driven by two vibration-type drive devices 620 and 640, respectively.

[0048] Although the detailed structure of the vibration drive device 620 is not shown, the vibration drive device 620 includes a vibration wave motor and a driving circuit of the vibration wave motor. The vibration drive device 620 moves the second lens group 320 in the optical axis direction. The vibration drive device 640 has a structure similar to the vibration drive device 620 and moves the fourth lens group 340 in the optical axis direction.

[0049] Figure 7B 7 is a block diagram illustrating a schematic configuration of an image pickup device 700. A first lens group 310, a second lens group 320, a third lens group 330, a fourth lens group 340, and a light amount adjustment unit 350 are arranged at respective predetermined positions on the optical axis inside a lens barrel 740. Light passing through the first lens group 310 to the fourth lens group 340 and the light amount adjustment unit 350 forms an image on an image pickup element 710. The image pickup element 710 converts an optical image into an electrical signal, and outputs and transmits the electrical signal to a camera processing circuit 750.

[0050] The camera processing circuit 750 performs amplification, gamma correction, or other processing on the output signal from the image pickup element 710. The camera processing circuit 750 is connected to a central processing unit (CPU) 790 via an automatic exposure (AE) gate 755, and is connected to the CPU 790 via an automatic focus (AF) gate 760 and an AF signal processing circuit 765. The video signal that has undergone a predetermined process in the camera processing circuit 750 is transmitted to the CPU 790 via the AE gate 755, the AF gate 760, and the AF signal processing circuit 765. The AF signal processing circuit 765 extracts a high frequency component of the video signal, generates an evaluation value signal of AF, and provides the generated evaluation value signal to the CPU 790.

[0051] The CPU 790 is a control circuit that generally controls the operation of the camera 700, and generates a control signal for determining exposure and focusing according to the acquired video signal. The CPU 790 controls the driving of the vibration-type drive devices 620, 640 and the meter 630 so that a determined exposure and an appropriate focusing state can be obtained, and adjusts the respective positions of the second lens group 320, the fourth lens group 340 and the light amount adjustment unit 350 in the optical axis direction. Under the control of the CPU 790, the vibration-type drive device 620 moves the second lens group 320 in the optical axis direction, the vibration-type drive device 640 moves the fourth lens group 340 in the optical axis direction, and the light amount adjustment unit 350 is driven and controlled by the meter 630.

[0052] The position of the second lens group 320 driven by the vibration drive device 620 in the optical axis direction is detected by the first linear encoder 770. The detection result is notified to the CPU 790 and fed back to the driving of the vibration drive device 620. Similarly, the position of the fourth lens group 340 driven by the vibration drive device 640 in the optical axis direction is detected by the second linear encoder 775. The detection result is notified to the CPU 790 and fed back to the driving of the vibration drive device 640. The position of the light amount adjustment unit 350 in the optical axis direction is detected by the aperture encoder 780. The detection result is notified to the CPU 790 and fed back to the driving of the meter 630.

[0053] Although an optical device having a configuration in which an optical element (such as a lens) is driven using the above-mentioned vibration actuator has been described, the optical device may also have a configuration in which an image pickup element or both an optical element and an image pickup element are driven using the vibration actuator. That is, an optical device including at least one of an optical element or an optical pickup element and driving at least one of the optical element and the image pickup element using the above-mentioned vibration actuator may be provided.

[0054] The vibration actuator may be used in other electronic devices without any limitation.An electronic device that drives a target member using the above-mentioned vibration actuator may be provided.

[0055] A vibration wave motor having a large output power and high attachment reliability can be provided. In addition, an electronic device including the vibration wave motor can also be provided.

[0056] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is intended that the scope of the appended claims cover all such modifications and equivalent structures and functions.

Claims

1. A vibration actuator, comprising: a vibrating body including an electric energy-mechanical energy conversion element and an elastic body bonded to each other via an adhesive; as well as a contact body, the contact body being in contact with the elastic body, wherein the vibrating body and the contact body are configured to move relative to each other through vibration of the vibrating body, Wherein, the elastomer comprises: a flat plate portion, the flat plate portion being bonded to the electrical energy-mechanical energy conversion element via the adhesive; and a protrusion extending to the flat plate portion and protruding from the flat plate portion, As a part of the adhesive, between the electrical energy-mechanical energy conversion element and the flat plate portion, the vibration actuator further includes: a first adhesive layer; and A second adhesive layer is adjacent to the first adhesive layer, the second adhesive layer having a thickness greater than that of the first adhesive layer and increasing toward the protruding portion.

2. The vibration actuator according to claim 1, wherein: The thickness of the first adhesive layer is 3 μm or less, and the thickness of the second adhesive layer is between 3 μm and 10 μm.

3. The vibration actuator according to claim 1, in, A curved portion is formed at a root of the protruding portion, the curvature of the curved portion being different from the curvature of the flat plate portion adjacent to the second adhesive layer, and In the section from the end of the first adhesive layer adjacent to the second adhesive layer to the inflection point of the curved portion, the length of the protrusion on the second adhesive layer in the radial direction is between 100 μm and 400 μm. 4 . The vibration actuator of claim 1 , further comprising an adhesive pool adjacent to the second adhesive layer that is not on a side of the first adhesive layer.

5. The vibration actuator according to claim 1, wherein: The elastic body is made of martensitic stainless steel, and a surface of the elastic body on the electrical-mechanical energy conversion element side is a surface in a state of being quenched after rolling.

6. The vibration actuator according to claim 5, wherein: The surface roughness Ra of the surface is between 0.025 μm and 0.2 μm.

7. The vibration actuator according to any one of claims 1 to 6, wherein: A difference between a maximum value and a minimum value of the thickness of the flat plate portion is 10 μm or less.

8. An optical device, comprising: A vibration actuator according to any one of claims 1 to 6; as well as At least one of an optical element and an image pickup element is configured to be driven by the vibration actuator.

9. An electronic device, comprising: member; as well as According to any one of claims 1-6, the vibration actuator is configured to drive the component.

10. A vibration actuator, comprising: a vibrating body including an electric energy-mechanical energy conversion element and an elastic body bonded to each other via an adhesive; as well as a contact body, the contact body being in contact with the elastic body, wherein the vibrating body and the contact body are configured to move relative to each other through vibration of the vibrating body, Wherein, the elastomer comprises: a flat plate portion, the flat plate portion being bonded to the electrical energy-mechanical energy conversion element via the adhesive; and a protrusion extending to the flat plate portion and protruding from the flat plate portion, As a part of the adhesive, between the electrical energy-mechanical energy conversion element and the flat plate portion, the vibration actuator further includes: a first adhesive layer; and A third adhesive layer, which is adjacent to the first adhesive layer and between the first adhesive layer and the end of the electric energy-to-mechanical energy conversion element, the thickness of the third adhesive layer increases toward the end and is 10μm or less, and the length of the third adhesive layer is between 100μm and 400μm.

11. The vibration actuator according to claim 10, wherein: A difference between a maximum value and a minimum value of the thickness of the flat plate portion is 10 μm or less.

12. An optical device, comprising: The vibration actuator according to claim 10; as well as At least one of an optical element and an image pickup element is configured to be driven by the vibration actuator.

13. An electronic device, comprising: member; as well as The vibration actuator according to claim 10, wherein the vibration actuator is configured to drive the member.

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