Vibration actuator and optical device that are miniaturized and suppress abnormal noise generation

Abstract

A vibration type actuator and an optical device that achieve miniaturization while suppressing abnormal noise generation. The vibration type actuator includes a vibration element having a piezoelectric element and an elastic member, and a contact body in contact with the vibration element. The contact body has a square rod shape in which a width and a thickness are substantially uniform in a length direction of the vibration element and the contact body moving relative to each other, and includes a first section and a second section in a region in which the contact body rubs and slides on the vibration element, the first section and the second section being formed with R surfaces having different radii of curvature, respectively, at edges extending in the length direction.

Description

Technical Field

[0001] This invention relates to vibratory actuators and optical devices. Background Technology

[0002] Vibration actuators are characterized by their ability to generate large thrust and achieve high-precision positioning, as well as their excellent quiet operation. They are widely used, for example, to drive focusing lenses or image blur correction lenses in camera equipment. Furthermore, in recent years, vibration actuators have been used as a drive source for panning or tilting mechanisms in lenses for surveillance cameras or webcams.

[0003] A vibratory actuator is a driving device that generates thrust (driving force) by causing a vibrating element and a contact body to come into frictional contact with each other, thereby exciting a predetermined vibration in the vibrating element and causing the vibrating element and the contact body to move relative to each other. Therefore, when driving a vibratory actuator, unwanted vibrations may sometimes be generated in the contact body due to the vibration excited in the vibrating element, and these unwanted vibrations in the contact body may sometimes cause abnormal noise. Therefore, it is desirable to prevent unwanted vibrations in the contact body when driving a vibratory actuator.

[0004] To suppress vibrations in the contact body, vibratory actuators are typically designed to prevent the driving frequency of the vibrating element from coinciding with the resonant frequency of the contact body. However, for example, contact bodies, as components of linear drive vibratory actuators, often exhibit not only typical vibrations such as out-of-plane, in-plane, and torsional vibrations, but also various characteristic vibration modes specific to their shape. To address this issue, Japanese Patent Application Publication No. 2018-67983 proposes a vibratory actuator (vibratory motor) designed such that the frequencies of the contact body in all characteristic vibration modes are far above a predetermined value from the driving frequency.

[0005] There is a strong demand for vibratory actuators to not only suppress the aforementioned abnormal noise but also to achieve miniaturization and weight reduction. To meet this requirement, for example, by reducing the thickness of the contact body, the resonant frequency of the contact body in its natural vibration modes typically shifts to a lower frequency side, and the frequency interval between adjacent frequency orders decreases (narrows). As a result, it is difficult to design vibratory actuators so that all natural vibration modes near the drive frequency are outside the drive band of the vibrating element, which may lead to the excitation of unnecessary vibrations in the contact body under certain drive conditions, resulting in abnormal noise in the audible range. Summary of the Invention

[0006] The present invention provides a vibration actuator that suppresses abnormal noise generation while achieving miniaturization, and an optical device including the vibration actuator.

[0007] In a first aspect of the invention, a vibration actuator is provided, comprising: a vibration element including an electromechanical energy conversion element and an elastic member; and a contact body in contact with the vibration element, the contact body having a length direction in which the vibration element and the contact body move relative to each other, the contact body having a square rod shape with a width and thickness substantially the same in the length direction, and the contact body including a first segment and a second segment in a region on the vibration element where it rubs and slides, the first segment and the second segment having R-surfaces with different radii of curvature at their edges extending along the length direction.

[0008] In a second aspect of the invention, a vibration actuator is provided, comprising: a vibration element including an electromechanical energy conversion element and an elastic member; and a contact body in contact with the vibration element, the contact body having an annular shape with a radial width and an axial thickness substantially the same, a surface parallel to the radial direction being a friction sliding surface for frictional sliding on the vibration element, and the contact body comprising a first segment and a second segment, the first segment and the second segment respectively having R-surfaces with different radii of curvature formed at their outer peripheries.

[0009] In a third aspect of the invention, an optical device is provided, comprising: a vibratory actuator; and an optical component driven by the vibratory actuator, the vibratory actuator comprising: a vibratory element including an electromechanical energy conversion element and an elastic member; and a contact body that contacts the vibratory element, the contact body having a length direction in which the vibratory element and the contact body move relative to each other, the contact body having a square rod shape with a width and thickness substantially the same in the length direction, and the contact body including a first segment and a second segment in a region on the vibratory element where it rubs and slides, the first segment and the second segment having R-surfaces with different radii of curvature at their edges extending along the length direction.

[0010] In a fourth aspect of the invention, an optical device is provided, comprising: a vibratory actuator; and an optical component driven by the vibratory actuator, the vibratory actuator comprising: a vibratory element including an electromechanical energy conversion element and an elastic member; and a contact body that contacts the vibratory element, the contact body having an annular shape with a radial width and an axial thickness substantially the same, a surface parallel to the radial direction being a friction sliding surface for frictional sliding on the vibratory element, and the contact body comprising a first segment and a second segment, the first segment and the second segment respectively having R-surfaces with different radii of curvature formed at their outer peripheries.

[0011] According to the present invention, a vibration actuator that suppresses abnormal noise generation while achieving miniaturization, and an optical device including the vibration actuator, can be obtained.

[0012] Other features of the invention will become apparent from the following description of exemplary embodiments (with reference to the accompanying drawings). Attached Figure Description

[0013] Figures 1A to 1D This is a diagram showing the overall structure of a linear drive type vibration actuator.

[0014] Figures 2A to 2C It is a diagram used to explain the vibration mode of a contact body under typical natural vibration modes.

[0015] Figures 3A to 3C This is a diagram used to explain the structure of the contact body used in the vibration actuator according to the first embodiment.

[0016] Figure 4A and Figure 4B It is used for explanation Figures 1A to 1D The contact bodies that appear in Figures 3A to 3C A diagram showing the inherent vibration modes of the contact bodies.

[0017] Figure 5 It is shown Figures 3A to 3C The diagram shows a torsional vibration pattern of the contact body with three peaks (crest).

[0018] Figures 6A to 6C It is shown Figures 3A to 3C A diagram showing a modified example of the contact body.

[0019] Figure 7 It is used to explain the use of Figures 6A to 6C The graph shows the changes in resonant frequencies under the natural vibration modes caused by the contact body.

[0020] Figure 8A and Figure 8B This is a diagram used to explain the structure of the contact body used in the vibration actuator according to the second embodiment.

[0021] Figures 9A to 9F It is used for explanation Figure 8A and Figure 8B The diagram shows the vibrational modes of the contact body under typical natural vibration modes.

[0022] Figures 10A to 10C This is a diagram showing the overall structure of the lens driving device.

[0023] Figure 11This is an exploded perspective view showing the overall structure of the gimbal drive device. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings illustrating embodiments thereof. Compared to vibratory actuators according to the prior art, vibratory actuators according to embodiments of the present invention have significant features in terms of the structure of the contact body; however, on the other hand, vibratory actuators can be formed without substantial differences in the construction of other components. Therefore, an example of a known construction of a vibratory actuator will be given first, followed by a description of the contact body, which is a characteristic component of vibratory actuators according to various embodiments of the present invention.

[0025] Figure 1A and Figure 1B This is an exploded perspective view of the linear drive type vibration actuator 1. Figure 1A and Figure 1B The orientations of the elements (components) of the vibratory actuator 1 differ from each other. Figure 1C This is a front view of the vibration actuator 1. Figure 1D This is a side view of the vibration actuator 1.

[0026] To clearly show the correspondence between the figures, and further, for ease of explanation, as... Figures 1A to 1D The X-axis (X direction), Y-axis (Y direction), and Z-axis (Z direction) are defined as mutually orthogonal as shown. When describing the components of the vibratory actuator 1, the directions represented by the X, Y, and Z directions will be explained respectively.

[0027] The vibration actuator 1 includes a vibration element 11, a contact body 12, a holding member 13, a pressure member 14, a guided member 15, a fixing member 16, a screw 17, and a rolling member 18. As an example of an electromechanical energy conversion element, the vibration element 11 has a rectangular plate-shaped elastic member 112 and a rectangular plate-shaped piezoelectric element 111. The piezoelectric element 111 is bonded to one of the two surfaces of the elastic member 112 facing the thickness direction (Z direction), i.e., two planes perpendicular to the Z direction, while the other surface has two protrusions 112a that protrude toward the contact body 12 with a predetermined spatial interval in the X direction. Furthermore, two opposite ends in the length direction (X direction) of the elastic member 112 are respectively provided with outwardly extending (along the ±X direction) holding portions 112b.

[0028] For example, the piezoelectric element 111 is formed of a piezoelectric ceramic of lead zirconate titanate (PZT), and the elastic member 112 is formed of a metal such as stainless steel. By applying an AC voltage of a predetermined frequency to the piezoelectric element 111, vibration of a predetermined vibration mode can be excited in the vibrating element 11, thereby causing the end of the protrusion 112a to undergo elliptical motion. Note that the mechanism for generating elliptical motion at the end of the protrusion 112a is known, and therefore a detailed description is omitted here.

[0029] The retaining part 112b is bonded and fixed to the retaining member 13. Therefore, the vibrating element 11 is held by the retaining member 13, thereby preventing the excitation of vibration from being suppressed. The pressure member 14 is, for example, a leaf spring, and the protrusion 112a makes pressure contact with the contact body 12 by using the reaction force generated by elastic deformation to press the retaining member 13 against the contact body 12. The guiding member 15 clamps the pressure member 14 between itself and the retaining member 13, thereby causing the pressure member 14 to elastically deform.

[0030] The guided member 15 has two guide grooves 15a extending in the driving direction (X direction) of the vibrating actuator 1. The fixed member 16 has two guide grooves 16a extending in the X direction, such that the guide grooves 16a are opposite to the two guide grooves 15a of the guided member 15 in the Z direction.

[0031] The contact body 12 is a square rod with its length direction in the X direction and orthogonal to the length direction, and its width (length in the Y direction) is greater than its thickness (length in the Z direction). Note that, as will be described later, the length direction of the contact body 12 is the direction in which the vibrating element 11 and the contact body 12 move relative to each other.

[0032] Corresponding portions of the contact body 12 at its two opposite ends near the longitudinal direction have holes extending through it in the thickness direction (Z direction). Screws 17 (fastening members) are inserted through the holes formed in the contact body 12 and fastened to the fixing member 16, thereby fixing the contact body 12 to the fixing member 16. The cross-section of the contact body 12 taken along a plane orthogonal to the longitudinal direction (X direction) (YZ plane) is consistent in the longitudinal direction.

[0033] Each has a spherical rolling member 18 (ball) sandwiched between a guide groove 15a formed in the guided member 15 and a guide groove 16a formed in the fixed member 16, thereby holding the guided member 15 in the fixed member 16 in such a way that the guided member 15 can only move in the X direction.

[0034] In the vibration actuator 1, when a predetermined vibration is excited in the vibration element 11 to cause the protrusion 112a to perform elliptical motion in the ZX plane, a driving force is generated at the contact surface between the protrusion 112a and the contact body 12 to move the vibration element 11 and the contact body 12 relative to each other in the X direction. This causes the vibration element 11, the holding member 13, the pressurizing member 14, and the guided member 15 to move in unison with respect to the contact body 12 and the fixing member 16 in the X direction, which is the driving direction.

[0035] Figures 2A to 2C This is a diagram used to explain the vibration mode of contact body 12 under typical natural vibration modes. Figure 2A The out-of-plane bending vibration of the contact body 12 with amplitude in the thickness direction (Z direction) is schematically shown. Figure 2B The in-plane bending vibration of the contact body 12 with amplitude in the width direction (Y direction) is schematically shown. Figure 2C The diagram schematically illustrates torsional vibration with a torsional amplitude about an axis along the length of the contact body 12, which serves as the axis of rotation. Here, although the diagram shows a resonant mode with the smallest resonant frequency among the associated vibrational modes, i.e., a resonant mode with a single vibrational peak, there are inherent vibrational modes with higher-order frequencies, each having multiple peaks, at frequencies higher than those shown.

[0036] Next, a vibration actuator according to a first embodiment of the present invention will be described. The vibration actuator according to the first embodiment and... Figures 1A to 1D The difference in the vibration actuator 1 shown is that, as a component of the vibration actuator 1, contact body 30 or contact body 30A, which will be described later, is used instead of contact body 12. Therefore, the following description will mainly focus on the construction of contact bodies 30 and 30A.

[0037] Figures 3A to 3C This is a diagram illustrating the structure of the contact body 30 used in the vibration actuator according to a first embodiment of the present invention. More specifically, Figure 3A This is a perspective view of the contact body 30. Note that, similar to contact body 12, the length, width, and thickness directions of contact body 30 are defined as the X, Y, and Z directions, respectively. Similar to contact body 12, contact body 30 has a square rod shape with approximately the same width and thickness.

[0038] Two opposite ends of the contact body 30 along its length direction (X direction) have fixing portions 32 for fastening the contact body 30 to the fixing member 16 using screws 17. A friction portion 31 is formed between the fixing portions 32 at the two opposite ends along the length direction. One of the front and back surfaces (the surfaces orthogonal to the Z direction (along the XY plane)) of the friction portion 31 forms a friction sliding surface associated with the protrusion 112a of the vibrating element 11.

[0039] The friction portion 31 has a first section and a second section. The first section and the second section have R-surfaces formed at two edges on the front side (+Z side) of the four edges extending along the length direction of the contact body 30, such that the radius of curvature of the R-surface of the first section is different from that of the R-surface of the second section. The first section is disposed approximately at the center of the friction portion 31 in the length direction, and the two second sections are disposed to sandwich the first section in the length direction.

[0040] Figure 3B This is a YZ cross-sectional view of the first segment of contact body 30 (showing a cross-section orthogonal to the X direction). Figure 3C This is a YZ cross-sectional view of the second segment of the contact body 30. For the two edges on the back side (-Z side) of the four edges extending along the length direction of the contact body 30, the first and second segments are identical in shape. However, for the two edges on the front side (+Z side) of the four edges extending along the length direction of the contact body 30, the radius of curvature of the R-surface of the first segment is relatively larger than the radius of curvature of the R-surface of the second segment. That is, the first segment has R-surfaces whose radii of curvature are all relatively larger than those of the R-surfaces of the second segment. The R-surface can be formed by rounding (including cutting, grinding, lapping, etc.). When the contact body 30 is formed by casting, the R-surface can also be formed using a mold.

[0041] Each R-surface of the first section is formed in the following region: on the front side (XY plane side), the region extends from the edge located on the front side for a length not greater than 1 / 4 of the width B of the contact body 30 (friction part 31), and on the side side (ZX plane side), it extends from the edge located on the side side for a length not greater than 1 / 2 of the thickness T of the contact body 30 (friction part 31). The amount of the portion of the first section removed by R rounding is configured not to exceed the maximum amount removed by C rounding under the constraints of the above-mentioned size range.

[0042] Note that the edges from which the first and second sections of the contact body 30 can be set are limited to the four edges extending along the length direction. Although in the contact body 30, R-faces with different radii of curvature are provided on the two edges located on the front side, R-faces with different radii of curvature can also be provided on the two edges located on the back side. Furthermore, R-faces with different radii of curvature can be provided on all four edges extending along the length direction. Furthermore, although in the contact body 30, the R-face with a large radius of curvature is only provided at one location on each edge located on the front side, the R-face with a large radius of curvature is not limited to being provided at one location, but can be provided at multiple locations (more specifically, two or four locations). Furthermore, although the radius of curvature of the R-faces in the first section of the contact body 30 is consistent, the radius of curvature of the R-faces in the first section can vary along the length direction. The length of the first section of the contact body 30 in the length direction is limited, and this limitation will be explained later.

[0043] The fixing part 32 is used to fix the contact body 30 to the fixing member 16 using screws 17, and is in the form of a U-shaped groove. The screw 17 is inserted through the U-shaped groove along the thickness direction and fastened to the fixing member 16, thereby fixing the contact body 30 to the fixing member 16. The contact body 30 is a structure in which the fixing part 32 and the friction part 31 are continuous with each other with the same thickness and the same width, but the thickness and shape of each fixing part 32 are not limited to this. For example, the thickness and width of each fixing part 32 may be different from those of the friction part 31. Similar to the contact body 12, through holes may be provided instead of U-shaped grooves, and furthermore, fixing may be achieved by means other than screws 17.

[0044] Next, the technical effects provided by the contact body 30 having the first section will be described. Figure 4A This is a diagram used to explain the inherent vibration modes of contact body 12. Figure 4B This is a diagram used to explain the inherent vibration modes of contact body 30. Figure 4A and Figure 4B In the middle, the horizontal axis represents the reference. Figures 2A to 2C The diagram illustrates the number of peaks under the three vibration modes (out-of-plane vibration, in-plane vibration, and torsional vibration), with the vertical axis representing the resonant frequency of each natural vibration mode. Note that only three vibration modes, namely out-of-plane vibration, in-plane vibration, and torsional vibration, are considered because the vibration modes to be considered in the low-frequency band in rod-shaped contact bodies 12 and 30, which both have four edges along their length, are reduced to these three types.

[0045] It is known that in a beam of fixed length, the resonant frequency increases with the number of peaks, and therefore, for contact bodies 12 and 30, the resonant frequency also increases with the number of peaks in each vibration mode of out-of-plane vibration, in-plane vibration and torsional vibration.

[0046] Contact body 12 does not have a segment corresponding to the first segment provided in contact body 30. Therefore, as Figure 4A As shown, the driving frequency band of the vibrating element 11 includes the resonant frequency of the torsional vibration mode (the resonant frequency of vibration with three peaks). On the other hand, since the contact body 30 is provided with a first section including an R-surface formed with a large radius of curvature, the resonant frequency of the torsional vibration with three peaks will shift towards the higher frequency side and outside the driving frequency band of the vibrating element 11.

[0047] Here, as from Figure 4A and Figure 4B The comparison clearly shows that the resonant frequency of out-of-plane vibration hardly changes, and further, the resonant frequency of in-plane vibration changes only slightly. Therefore, by setting a first segment in the contact body, the resonant frequency of torsional vibration can be selectively shifted away from the driving frequency band of the vibrating element 11, resulting in the suppression of abnormal noise when driving the vibrating actuator.

[0048] Reference Figure 5 This explains why the resonant frequencies of in-plane and out-of-plane vibrations remain almost unchanged, but the resonant frequencies of torsional vibrations change significantly. Figure 5 This is a schematic diagram showing the torsional vibration pattern of the contact body 30 with three peaks. The apex of the torsional vibration peak exists within the first section of the contact body 30. At this time, the mass of the torsional vibration peak decreases due to the amount of the portion removed from the edge by forming a large radius of curvature R-surface in the first section, resulting in a higher resonant frequency. Furthermore, the apex of a torsional vibration peak with a single peak also exists in the first section. Therefore, the resonant frequency of the torsional vibration with a single peak also increases. In other words, by providing a first section with a large radius of curvature R-surface in the contact body 30, the resonant frequency of the torsional vibration with an odd number of peaks is increased.

[0049] On the other hand, when the torsional vibration has an even number of peaks, the nodes of the torsional vibration exist in the first segment. In this case, due to the presence of a large radius of curvature (R-surface) in the first segment, the portion of the torsional vibration experiencing large distortion is eliminated, resulting in a lower resonant frequency for the torsional vibration with an even number of peaks. In other words, the first segment is far from the neutral axis of the torsional vibration, which has a significant impact on the geometric moment of inertia, thus reducing the resonant frequency by an amount corresponding to the mass eliminated by the large radius of curvature (R-surface).

[0050] Next, the limitation on the length of the first segment in the longitudinal direction will be described. When the first segment is positioned at the antinode of the vibration, this provides the effect of shifting the resonant frequency of the vibration to a higher frequency side. Therefore, it is necessary to set the length of the first segment in the longitudinal direction to be the length between nodes of a vibration having a frequency order (i.e., a length not greater than 1 / 2 the wavelength) such that the resonant frequency of that frequency order is located outside the driving frequency band. In the contact body 30, it is desirable to set the length of the first segment in the longitudinal direction to be no greater than 1 / 2 the wavelength of a torsional vibration having three peaks.

[0051] Note that for both out-of-plane and in-plane vibrations, the first segment, which forms an R-plane with a large radius of curvature, partially eliminates the portion experiencing large distortion, thus causing the resonant frequency to change via the same mechanism as torsional vibrations. However, the first segment has a very small effect on the geometric moment of inertia under both out-of-plane and in-plane vibrations.

[0052] As described above, in the contact body 30, by providing a first section with a large radius of curvature R-surface in the edge extending along the length direction, the resonant frequency of torsional vibration can be controlled without affecting the resonant frequencies of out-of-plane and in-plane vibrations. Therefore, the resonant frequency of torsional vibration can be shifted out of the driving frequency band of the vibration element 11, thereby suppressing the generation of abnormal noise.

[0053] Next, a modified example of the contact body 30 will be described. Figures 6A to 6C This is a diagram used to explain the structure of contactor 30A. Figure 6A This is a three-dimensional view of the contact 30A. Figure 6B This is the YZ cross-sectional view of the first section of contact body 30A. Figure 6C This is the YZ cross-sectional view of the second section of contact body 30A.

[0054] The difference between contact body 30A and contact body 30 is that step S is provided to narrow the width of the first segment, but the other structures are the same as those of contact body 30. Therefore, in Figures 6A to 6C The first section is clearly illustrated in the diagram, and the reference numerals for other parts are omitted. The following description will mainly focus on the first section with step S.

[0055] The side surface of the first section is formed with corresponding steps by removing a specific depth along the Y direction, thereby making the width of the first section narrower than that of the second section. Furthermore, in the length direction, within the range where the steps S are provided, the first section forms an R-surface with a radius of curvature that is larger than the radius of curvature of the R-surface of the second section.

[0056] Figure 7This is a graph used to explain the changes in resonant frequencies in the inherent vibration modes caused by the use of contact body 30A in a vibratory actuator. Figure 7 In the middle, a contact body without a first segment (having a connection with) is drawn. Figures 1A to 1D The resonant frequencies of the contact body 12 (which has the same structure as the contact body shown) in various vibration modes are as follows. Here, the driving frequency band includes the resonant frequencies of torsional vibration and in-plane vibration, both of which have two peaks. (Refer to...) Figure 4A and Figure 4B In the description, the influence of the large radius of curvature R on the geometric moment of inertia of in-plane vibration is very small. On the other hand, in contact body 30A, due to the step S provided in the side surface in the width direction, the part experiencing large distortion is not flat, which has a significant impact on the geometric moment of inertia of the in-plane vibration mode, causing the resonant frequency of the in-plane vibration to shift to a lower frequency side. Therefore, by shifting the resonant frequency of the in-plane vibration with two peaks to a lower frequency side, it is possible to move the resonant frequency outside the driving frequency band, a state determined by... Figure 7 The arrow in the image indicates this.

[0057] Therefore, by setting the first section, the resonant frequencies of torsional vibration and in-plane vibration can be selectively shifted outside the driving frequency band, thereby suppressing the generation of abnormal noise. Note that although in the contact body 30A, the width of the first section is narrower than the width of the second section by setting the step S, conversely, the resonant frequencies of torsional vibration and in-plane driving can also be selectively shifted outside the driving frequency band by making the width of the first section larger than the width of the second section.

[0058] Next, a description of the contact body for a vibration actuator according to a second embodiment of the present invention will be given. The vibration actuator according to the second embodiment performs as described later. Figure 11 The described rotary-driven vibratory actuator includes a contact body with an annular shape. (See below for further details.) Figure 11 The overall structure of the vibration actuator according to the second embodiment will be described in detail here, with the structure of the contact body having an annular shape.

[0059] Figure 8A This is a perspective view of the contact body 60 for a vibratory actuator according to a second embodiment of the present invention. The contact body 60 has an annular shape and has an inner peripheral portion and an outer peripheral portion with different thicknesses. The inner peripheral portion of the contact body 60 is the portion for connection with a rotating body (not shown), and its thickness is less than that of the outer peripheral portion. The outer peripheral portion has a thickness T and a radial width B, and one of its radially parallel front and back faces forms a friction sliding surface that slides on the vibrating element 11 (not shown).

[0060] The outer periphery of the contact body 60 is formed with multiple first segments at equal intervals in the circumferential direction, and the portions between adjacent first segments form second segments. The first segment is a segment with an R-surface of large radius of curvature formed on its outer periphery, and the second segment is a segment with an R-surface of relatively smaller radius of curvature than the R-surface of the first segment. Figure 8B It is along Figure 8A The cross-sectional view taken from section AA shows the cross-section of the first segment. The contact body 60 has an R-surface with a large radius of curvature located at the outer periphery of both the front and back sides. Note that the edges where the R-surface with a large radius of curvature can be formed are not limited to the outer periphery of the front and back sides, and the R-surface is not formed at the inner periphery edge of the outer periphery. Here, although the R-surface with a large radius of curvature is located at the outer periphery of both the front and back sides, the R-surface can be formed at only one of the outer periphery edges.

[0061] like Figure 8B As shown, the R-surface in each first segment of the contact body 60 is formed in a region that extends from the associated edge on both the front and back sides by a length not greater than 1 / 4 of the width B of the contact body 60, and on the outer peripheral side, extends from the associated outer peripheral edge by a length not greater than 1 / 2 of the thickness T of the contact body 60. The amount of the portion of the first segment removed by the R-rounding is configured not to exceed the maximum amount removed by the C-rounding under the constraints of the aforementioned size range. The other construction of the first segment is similar to that of the first segment of the contact body 30, and therefore its description is omitted.

[0062] Figures 9A to 9F It is a diagram used to explain the vibration mode of contact body 60 under typical natural vibration modes. Figure 9A and Figure 9B This is a schematic diagram showing the out-of-plane bending vibration of the contact body 60 with amplitude in the axial direction. Figure 9C and Figure 9D This is a schematic diagram showing the in-plane bending vibration of the contact body 60 with amplitude in the radial direction. Figure 9E and Figure 9F This is a schematic diagram illustrating torsional vibration with torsional amplitude about a rotational axis in the circumferential direction around the contact body 60. Here, although... Figures 9A to 9F The resonant modes, all having six vibrational peaks, are shown with the help of typical examples, but there are inherent vibrational modes with different numbers of peaks on the lower and higher frequency sides.

[0063] The vibration modes of contact body 60 are characterized in that, even vibration modes with the same number of peaks typically include two modes, referred to as sin modes and cos modes. One of these modes has a peak position in the first segment, while the other has a node position in the first segment. In this case, the former reduces the mass at the peak position, thus resulting in a higher resonant frequency for torsional vibration. Conversely, the latter has a portion where the large distortion position is eliminated, which lowers the resonant frequency for torsional vibration. Therefore, a difference will occur between the resonant frequencies of the sin and cos modes of torsional vibration modes with the same number of peaks.

[0064] In a vibration actuator driven by a friction-driven annular contact, it is known that abnormal noise is generated by exciting a traveling wave of a specific vibration mode within the contact. However, in contact 60, the resonant frequencies of the sine and cosine modes that generate the traveling wave differ, thus the vibrational energy from the vibrating element does not lead to the generation of the traveling wave, thereby suppressing the generation of abnormal noise. Note that the formation of a large radius of curvature R-surface does not significantly affect the resonant frequencies of both out-of-plane and in-plane vibration modes, for the same reason as in contact 30.

[0065] Therefore, in the annular contact body 60, by providing a first section with a large radius of curvature R-surface at the outer periphery, the resonant frequency of torsional vibration can be controlled without substantially affecting out-of-plane and in-plane vibrations. As a result, the generation of abnormal noise can be suppressed.

[0066] Next, an example of an optical device using a vibratory actuator will be described. Figure 10A This is a diagram showing the overall structure of the lens driving device 40. Figure 10B This is the front view of the lens drive device 40. Figure 10C This is a side view of the lens drive device 40.

[0067] Figures 10A to 10C The lens driving device 40 shown is used functionally with Figures 1A to 1D The vibration actuator 1 shown is the same as the vibration actuator shown, therefore the same reference numerals are used and a detailed description is omitted. Figures 10A to 10C The structure of the lens drive device 40 is shown in a simplified manner. The lens drive device 40 includes a vibrating actuator 1, an optical lens 41 (optical component), a lens holding member 42, and a guide member 43.

[0068] The optical lens 41 is, for example, a focusing lens used in the lens barrel of a camera device. A lens holding member 42 holds the optical lens 41. A guide member 43 is inserted through a hole formed in the lens holding member 42, and in this state, the two opposite ends of each guide member 43 are fixed inside the lens barrel substantially parallel to the optical axis O of the optical lens 41. Thus, the optical lens 41 is guided by the guide member 43, allowing the optical lens 41 to move along the optical axis.

[0069] The lens holding member 42 is provided with a fitting portion 42b. Furthermore, the guided member 15 of the vibrating actuator 1 is provided with a fitting protrusion 15b that fits into the fitting portion 42b. The fixing member 16 is fixed at a predetermined position within the lens barrel, such that the fitting protrusion 15b fits into the fitting portion 42b, and the direction of movement of the guided member 15 is approximately parallel to the optical axis O. Therefore, by driving the vibrating actuator 1 to move the guided member 15 along the optical axis, the optical lens 41 can be moved along the optical axis.

[0070] In the lens barrel equipped with the lens drive device 40, there is a strong demand for miniaturization of the vibratory actuator in order to achieve miniaturization of the lens barrel. As mentioned above, since the resonant frequency of the contact body in its inherent vibration mode enters the drive frequency band, miniaturization of the vibratory actuator may lead to the generation of abnormal noise in the audible range. To solve this problem, the contact body 30 structure described above is applied to the contact body, which is a component of the vibratory actuator. This allows for miniaturization of the vibratory actuator by making the contact body thinner and smaller while suppressing the generation of abnormal noise.

[0071] Figure 11 This is an exploded perspective view of the pan / tilt driving device 50 using a vibration actuator. The camera unit 57 supports a lens barrel 58 containing optical components such as various lenses and apertures, allowing the lens barrel 58 to rotate about the pitch axis TL. The camera unit 57 is the driven component of the pan / tilt driving device 50 and is supported by an intermediate cover 59, allowing the camera unit 57 to rotate about the pan / tilt axis PN in sync with the lens barrel 58. A connecting member 56 is connected to a contact body 60 using screws 55, thereby connecting the contact body 60 and the camera unit 57 to each other. The intermediate cover 59 is fixed to the base 54.

[0072] exist Figure 11The overall structure of the vibratory actuator 1 is not shown. The vibratory actuator 1 is held on the actuator support plate 51, which is fixed to the base 54. The two protrusions 112a of the vibrating element 11 contact the surface of the contact body 60 located on the -Y side. The driving force of the vibratory actuator acts along the tangential direction of the contact body 60, causing the contact body 60 to rotate about the pan-tilt axis PN, thereby also causing the camera unit 57 to rotate about the pan-tilt axis PN. The contact body 60 holds a scale 53 for position detection. The scale 53 is disposed on the surface opposite to the position detection sensor 52 fixed to the actuator support plate 51, and the rotation angle of the contact body 60 can be determined by the position detection sensor 52. Note that as an actuator for driving the lens barrel 58 to rotate about the pitch axis TN, an actuator equivalent to the actuator that rotates the camera unit 57 about the pan-tilt axis PN can be used.

[0073] In the gimbal drive device 50, the vibration actuator can also be miniaturized while suppressing the generation of abnormal noise, for the same reason as the lens drive device 40.

[0074] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the claims should be accorded the broadest interpretation to include all such variations, equivalent structures, and functions.

[0075] This application claims priority to Japanese Patent Application No. 2021-031805, filed on March 1, 2021, the entire contents of which are incorporated herein by reference.

Claims

1. A vibration actuator, comprising: Vibrating elements, which include electromechanical energy conversion elements and elastic components; as well as The contact body, which is in contact with the vibrating element, The contact body is characterized in that, with the direction in which the vibrating element and the contact body move relative to each other as its length direction, the contact body has a square rod shape with a width and thickness that are approximately the same in the length direction, and the region in which the contact body rubs and slides on the vibrating element includes a first segment and a second segment, the first segment being sandwiched between two second segments in the length direction, and the first segment and the second segment respectively forming R-surfaces with different radii of curvature at their edges extending along the length direction. Wherein, the radius of curvature of the first section is greater than the radius of curvature of the second section, and the first section is located at a position corresponding to the antinode or node of the contact body in torsional vibration mode, and The length of the first segment in the direction in which the contact body moves relative to the vibrating element is no greater than 1 / 2 of the wavelength of the torsional vibration mode of the drive frequency band closest to the vibrating element.

2. The vibration actuator according to claim 1, wherein, The contact body has multiple first segments.

3. The vibration actuator according to claim 1, wherein, The width of the first segment is smaller than the width of the second segment.

4. The vibration actuator according to claim 3, wherein, In the first section, in the direction in which the contact body moves relative to the vibrating element, the length of the region formed by the R-surface is shorter than the length of the region whose width is smaller than that of the second section.

5. The vibration actuator according to claim 1, wherein, In a cross section orthogonal to the direction of movement of the contact body relative to the vibrating element, the R-surface in the first segment is formed in a region that extends from the edge on a surface parallel to the width direction for a length not greater than 1 / 4 of the width, and on a surface parallel to the thickness direction for a length not greater than 1 / 2 of the thickness from the edge.

6. A vibration actuator, comprising: Vibrating elements, which include electromechanical energy conversion elements and elastic components; as well as The contact body, which is in contact with the vibrating element, The contact body is characterized by having an annular shape with a radial width and axial thickness that are approximately the same, and a surface parallel to the radial direction serving as a friction sliding surface for frictional sliding on the vibrating element. Furthermore, the contact body comprises a first segment and a second segment. Multiple first segments are formed at equal intervals along the circumference of the contact body, and the portions between adjacent first segments form the second segment. The first segment and the second segment each have an R-surface with a different radius of curvature formed at their outer periphery. Wherein, the radius of curvature of the first section is greater than the radius of curvature of the second section, and the first section is located at a position corresponding to the antinode or node of the contact body in torsional vibration mode, and The length of the first segment in the direction in which the contact body moves relative to the vibrating element is no greater than 1 / 2 of the wavelength of the torsional vibration mode of the drive frequency band closest to the vibrating element.

7. The vibration actuator according to claim 6, wherein, The width of the first segment is smaller than the width of the second segment.

8. The vibration actuator according to claim 7, wherein, In the first section, in the direction in which the contact body moves relative to the vibrating element, the length of the region formed by the R-surface is shorter than the length of the region whose width is smaller than that of the second section.

9. The vibration actuator according to claim 6, wherein, In a cross section orthogonal to the direction of movement of the contact body relative to the vibrating element, the R-surface in the first segment is formed in a region that extends from the edge on a surface parallel to the width direction for a length not greater than 1 / 4 of the width, and on a surface parallel to the thickness direction for a length not greater than 1 / 2 of the thickness from the edge.

10. An optical device, comprising: Vibration actuator; and Optical components, driven by the vibratory actuator, The vibration actuator includes: Vibrating elements, including electromechanical energy conversion elements and elastic components; and The contact body, which is in contact with the vibrating element, The contact body is characterized in that, with the direction in which the vibrating element and the contact body move relative to each other as its length direction, the contact body has a square rod shape with a width and thickness that are approximately the same in the length direction, and the region in which the contact body rubs and slides on the vibrating element includes a first segment and a second segment, the first segment being sandwiched between two second segments in the length direction, and the first segment and the second segment respectively forming R-surfaces with different radii of curvature at their edges extending along the length direction. Wherein, the radius of curvature of the first section is greater than the radius of curvature of the second section, and the first section is located at a position corresponding to the antinode or node of the contact body in torsional vibration mode, and The length of the first segment in the direction in which the contact body moves relative to the vibrating element is no greater than 1 / 2 of the wavelength of the torsional vibration mode of the drive frequency band closest to the vibrating element.

11. An optical device, comprising: Vibration actuator; and Optical components, driven by the vibratory actuator, The vibration actuator includes: Vibrating elements, including electromechanical energy conversion elements and elastic components; and The contact body, which is in contact with the vibrating element, The contact body is characterized by having an annular shape with a radial width and axial thickness that are approximately the same, and a surface parallel to the radial direction serving as a friction sliding surface for frictional sliding on the vibrating element. Furthermore, the contact body comprises a first segment and a second segment. Multiple first segments are formed at equal intervals along the circumference of the contact body, and the portions between adjacent first segments form the second segment. The first segment and the second segment each have an R-surface with a different radius of curvature formed at their outer periphery. Wherein, the radius of curvature of the first section is greater than the radius of curvature of the second section, and the first section is located at a position corresponding to the antinode or node of the contact body in torsional vibration mode, and The length of the first segment in the direction in which the contact body moves relative to the vibrating element is no greater than 1 / 2 of the wavelength of the torsional vibration mode of the drive frequency band closest to the vibrating element.

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