Vibration-type driving device and image pickup apparatus using the same

Abstract

A vibration-type driving device that realizes low cost and high precision while reducing a driving load. A driving unit has a vibrator with a protruding portion and generates a driving force by vibrating the vibrator. A first unit has a contact portion with which the protruding portion is in pressure contact in a first direction. A second unit rotates relative to the first unit about a rotation axis parallel to the first direction by the driving force. Three or more support members are located between the first unit and the second unit in the first direction to rotatably support the first unit and the second unit. The support members are positioned such that, during relative rotation of the first unit and the second unit, a contact point at which the protruding portion is in contact with the contact portion is always located in at least one triangular region formed by connecting any three of the support members with straight lines when viewed in the first direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a vibration type drive device that generates a rotational driving force by vibration and frictional force, and an image pickup apparatus using the vibration type drive device. BACKGROUND

[0002] Some conventional electronic devices such as image pickup apparatuses employ a vibration type drive device that generates a rotational driving force by excited vibration and frictional force. A rotational ultrasonic motor having a small size, a high output, and quietness and the like is known as a vibration type drive device. Japanese Patent Application Publication No. JP 2018-189745 (JP 2018-189745 A) discloses an ultrasonic motor that employs a ring-shaped vibrator. Japanese Patent Application Publication No. JP 2006-158054 (JP 2006-158054 A) and Japanese Patent Application Publication No. JP 2004-304887 (JP 2004-304887 A) disclose ultrasonic motors that employ a reed type vibrator. For example, when the ultrasonic motor is used for lens driving of a camera, the vibrator is in pressure contact with a friction member connected to a lens frame. And the lens frame is rotationally driven by transmitting the elliptical motion generated by the vibrator to the friction member.

[0003] Incidentally, since the driving unit of the vibration type drive device drives the driven unit while always receiving pressure, driving force loss due to sliding friction caused by pressure occurs. Therefore, in order to reduce such driving force loss due to sliding friction, JP 2018-189745 A and JP 2006-158054 A disclose a configuration that receives pressure by a rolling member such as a ball.

[0004] However, sliding friction that generates driving force loss also occurs in the radial direction. For example, the configuration in JP 2018-189745 A supports a rotating cylinder that is pressed in the thrust direction with rollers arranged in the circumferential direction, and prevents wobble during radial rotation driving by fitting a protrusion portion formed on the end surface in the thrust direction of the rotating cylinder to the inner surface of each roller. According to this configuration, since sliding friction occurs in the fitting portion in the radial direction of the rotating cylinder, driving force loss also occurs at this position. Furthermore, since the protrusion portion of the rotating cylinder is fitted to the inner surface of the roller at a position that is radially outward of the position where the vibrator is in pressure contact, the loss in the fitting portion greatly affects the driving force loss. Therefore, there is room for improvement in terms of reducing the driving load.

[0005] Further, the configuration of JP 2006-158054 A supports the rotating cylinder pressed in the thrust direction by sandwiching the ball between the V-shaped grooves provided along the circumference of the rotor body and the bearing seat, and prevents the wobble in the radial direction during the rotational drive. Since this configuration supports the rotating cylinder by the rolling friction in both the thrust direction and the radial direction, the loss of the driving force is reduced. However, in order to make the diameters of the V-shaped grooves uniform and eliminate the eccentricity, an extremely high machining precision is required, which increases the cost. Therefore, it is difficult to achieve both the cost reduction and the high machining precision.

[0006] Further, both JP 2006-158054 A and JP 2004-304887 A propose a vibration motor configured such that a relatively small-sized vibrator is in pressure contact with the annular friction member at only specified positions on the circumference of the friction member. Since the vibrator is small in size, this vibration motor is advantageous for the miniaturization.

[0007] However, since the friction member is restrained at only the specified positions on the circumference, the friction member tends to generate unnecessary resonance due to the less restraint, which can become an obstacle to the driving force of the vibrator and can reduce the driving performance as a vibration motor. Meanwhile, the friction member can be fixed to the fixed member with a screw to prevent the unnecessary resonance of the friction member. However, if the friction member is not fixed to the fixed member in any clever way, it is possible to generate the unnecessary resonance or cause the entire unit to be large-sized. SUMMARY

[0008] The present application provides a vibration-type driving device that achieves low cost and high precision while reducing the driving load.

[0009] Therefore, the present application provides a vibration-type driving device including: a driving unit having a vibrator provided with a protruding portion and configured to generate a driving force by vibrating the vibrator; a first unit having a contact portion, the protruding portion being in pressure contact with the contact portion in a first direction; a second unit configured to relatively rotate with respect to the first unit around a predetermined rotation axis parallel to the first direction by the driving force of the driving unit; and three or more support members located between the first unit and the second unit in the first direction and configured to support the first unit and the second unit so as to be relatively rotatable. The support members are positioned such that, during the relative rotation of the first unit and the second unit, a contact point at which the protruding portion contacts the contact portion is always located in at least one of one or more triangular regions formed by connecting any three of the three or more support members with straight lines when viewed in the first direction.

[0010] According to the present application, it is possible to provide a vibration-type driving device that achieves low cost and high precision while reducing the driving load.

[0011] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing an electronic device that uses a vibration motor as a vibration-type drive device according to a first embodiment of the present invention.

[0013] Figure 2 This is an exploded perspective view of the vibration motor.

[0014] Figure 3 This is an exploded perspective view of the vibration motor.

[0015] Figure 4 This is a cross-sectional view showing the main parts of a vibration motor, including the driven body shown in simplified form.

[0016] Figure 5A and Figure 5B This is a schematic diagram illustrating the vibration modes of a vibrator included in a vibration motor, and Figure 5C This is a schematic diagram showing the projection of a vibrator performing elliptical motion.

[0017] Figure 6 This is an exploded perspective view showing the main parts of the structure that holds the ball included in the vibrating motor.

[0018] Figure 7A and Figure 7B This is a view illustrating the configuration of the rolling ball as viewed from the -Y side.

[0019] Figure 8A and Figure 8B This is a view illustrating the configuration of the rolling ball as viewed from the -Y side.

[0020] Figure 9A and Figure 9B This is an exploded perspective view showing the driven body included in the vibration motor.

[0021] Figure 10 This is a cross-sectional view showing the main parts of the vibration motor and the driven body in detail.

[0022] Figure 11 It is an exploded perspective view of the main parts of the structure that retains the rolling ball, wherein the rolling ball is included in a vibration motor as a vibration type drive device according to a second embodiment of the present invention.

[0023] Figure 12A and Figure 12B This is a view illustrating the configuration of the rolling ball as viewed from the -Y side. Detailed Implementation

[0024] An embodiment according to the present application will be described in detail below with reference to the drawings.

[0025] Figure 1 is a schematic view showing an electronic device to which a vibration motor as a vibration-type drive device according to a first embodiment of the present application is applied. As the electronic device, a rotational drive device 1 is exemplified. The rotational drive device 1 includes a fixed body 10 and a movable body 20 that rotates with respect to the fixed body 10. The fixed body 10 further includes a control substrate (not shown) that controls the entire rotational drive device 1 except for a vibration motor 100 as a vibration-type drive device. The vibration motor 100 is shown by a cross-sectional view. The movable body 20 includes an imaging device 21 as an image pickup unit that can take an image of a subject. Note that the entire rotational drive device 1 can be referred to as an imaging device.

[0026] The vibration motor 100 is a rotational ultrasonic motor provided with a vibrator 101 (to be mentioned later) that rotates a driven body 121 using vibration. The movable body 20 is connected to the driven body 121 of the vibration motor 100. When the vibrator 101 rotationally moves the driven body 121, the movable body 20 including the imaging device 21 rotates around a rotation axis P passing through the rotation center. The imaging direction of the imaging device 21 changes as the movable body 20 rotates.

[0027] The rotational drive device 1 is configured to be used in a state where the movable body 20 is connected to the driven body 121 and a support body 122 is fixed. Conversely, the rotational drive device 1 can be configured to be used in a state where the movable body 20 is connected to the support body 122 and the driven body 121 is fixed.

[0028] Figure 2 and Figure 3 is an exploded perspective view showing the vibration motor 100. Figure 4 is a cross-sectional view showing a main part of the vibration motor 100 including the driven body 121 shown in a simplified form.

[0029] Hereinafter, the directions of members will be referred to with reference to X, Y, and Z coordinate axes shown in Figure 2 , Figure 3 and the like. In the present embodiment, the direction parallel to the rotation axis P is defined as the Y direction. In particular, the side on which the driven body 121 is located with respect to the vibrator 101 is the +Y side in the Y direction. The longitudinal direction of the vibrator 101 coinciding with the tangential direction of the driven body 121 is defined as the Z direction. The direction that intersects perpendicularly with both the Y direction and the Z direction is defined as the X direction.

[0030] The vibration motor 100 mainly has a driven body 121 constituting a first unit, a support body 122 constituting a second unit, and a chassis 122d. The support body 122 holds the entire vibration motor 100. The driven body 121 is shaped as a whole in an approximate ring shape. The driven body 121 has a shaft 121a, a rolling receiving portion 121b, and a contact surface (contact portion) 121s. The contact surface 121s is a friction surface. A rotation support hole 122a is formed in the support body 122. The shaft 121a of the driven body 121 is rotatably fitted into the rotation support hole 122a. Thus, the entire driven body 121 is relatively rotatable about a rotation axis P with respect to the support body 122. Therefore, the support structure in the radial direction of the vibration motor 100 is a sliding bearing structure.

[0031] Since the vibration motor 100 has a simple structure that determines the fitting relationship in the radial direction by the rotation support hole 122a and the shaft 121a, the assembly accuracy is easily ensured at a relatively low cost. Note that the driven body 121 can be constituted by a single member, or can be constituted by a disc-shaped member including the contact surface 121s and the rolling receiving portion 121b, and a separate member of the shaft 121a. Alternatively, the relationship between the shaft 121a and the rotation support hole 122a can be reversed. That is, a shaft provided in the support body 122 can be fitted into a rotation support hole provided in the driven body 121, so that the entire driven body 121 will be relatively rotatable about the support body 122.

[0032] The vibrator 101 as a member of the drive unit has an elastic body 102 and a piezoelectric device 103. The piezoelectric device 103 is an electromechanical energy conversion element that excites vibration in the elastic body 102. The piezoelectric device 103 is made of, for example, lead zirconate titanate (PZT). The elastic body 102 is constituted by a metal plate made of stainless steel or the like.

[0033] The elastic body 102 has two protruding portions 102a arranged in the longitudinal direction and a held portion 102b Figure 2 ). The elastic body 102 and the piezoelectric device 103 are adhered by an adhesive or the like. Since the piezoelectric device 103 is pressed by a pressure applying mechanism described later in a state where the elastic body 102 and the piezoelectric device 103 are adhered, the protruding portions 102a are in pressure contact with the contact surface 121s. Vibration of a frequency in the ultrasonic wave range (ultrasonic wave vibration) occurs in each of the protruding portions 102a of the elastic body 102 by application of a driving voltage of a high-frequency alternating current to the piezoelectric device 103 Figure 5C ). Thus, a driving force is generated between the protruding portions 102a and the contact surface 121s. The driving force F2 Figure 3 ) mentioned later acts at a position where the protruding portions 102a are in contact with the contact surface 121s.

[0034] A rolling receiving portion 122b facing the rolling receiving portion 121b of the driven body 121 is formed in the support body 122. A rolling ball (six in number) 108 is disposed between the rolling receiving portions 121b and 122b. That is, the support structure with respect to the thrust direction of the vibration motor 100 is a rolling bearing structure, and the driven body 121 and the support body 122 can smoothly rotate with respect to each other by rotation of the rolling ball 108. Thus, it is possible to make the frictional resistance caused when the driven body 121 moves while receiving pressure as small as possible. Figure 2

[0035] Although the rolling receiving portion 122b and the support body 122 can be constituted by a single member, they can be constituted by separate members. Also, although the rolling receiving portion 121b and the driven body 121 can be constituted by a single member, they can be constituted by separate members. Note that, instead of the rolling ball 108, a rolling member such as a roller or a sliding member can be disposed between the rolling receiving portion 122b and the rolling receiving portion 121b.

[0036] The first holder 104 holds the elastic body 102 fixed by holding the held portion 102b of the elastic body 102. Thus, the vibrator 101 moves together with the first holder 104. A chassis 122d is fixed to the support body 122. The frame member 113 holds the first holder 104 by an elastic connecting member 114. The first holder 104 is positioned and fixed to the driven body 121 by fixing the frame member 113 to the chassis 122d with a screw 115.

[0037] The interception member 105 has a function of intercepting transmission of vibration to other members. The interception member 105 intercepts transmission of the ultrasonic vibration of the piezoelectric device 103 to the small base 106 (mentioned later) but does not attenuate the ultrasonic vibration of the piezoelectric device 103. A felt fabric is suitable as the material of the interception member 105. The small base 106 is in surface contact with the piezoelectric device 103 through the interception member 105, and has a function of transmitting the pressure of the pressurizing spring 111 to the piezoelectric device 103.

[0038] ​The pressure applying mechanism includes a pressure applying member 110, a pressure spring 111 as a pressure applying means, and a receiving member 112. The second holder 107 holds the pressure applying mechanism. The second holder 107 is fixed to the chassis 122d with two screws 115 together with a frame member 113. An attachment hole 112a, which is a circular hole, is formed in the center of the receiving member 112. A threaded portion 112b is formed on the outer peripheral surface of the receiving member 112. The receiving member 112 is fixed to the second holder 107 by screwing the threaded portion 112b into a threaded hole 107a of the second holder 107. Further, the attachment hole 112a engages and holds an attachment shaft 110a of the pressure applying member 110. The pressure applying member 110 is attached to the attachment hole 112a of the receiving member 112 and is held so as to be movable only in a direction substantially perpendicular to the contact surface 121s of the driven body 121.

[0039] The pressure applying member 110 transmits the pressure from the pressure spring 111 to the vibrator 101 through the small base 106 and the intercepting member 105. Thereby, the vibrator 101 is in pressure contact with the driven body 121. The pressure spring 111 includes, for example, a compression spring. One end of the pressure spring 111 is fixed to the receiving body 112, and the other end abuts the pressure applying member 110. In this way, the pressure spring 111 generates a pressure Fl by fixing both ends in a compressed state. The generated pressure Fl becomes a force in a direction (+Y direction) perpendicular to the contact surface 121s of the driven body 121 by being transmitted to the piezoelectric device 103. The vibrator 101 is in pressure contact with the driven body 121 by the pressure Fl. Therefore, the +Y direction is the pressure applying direction of the pressure spring 111. The roll ball 108 is an example of a sliding member that receives the pressure Fl between the driven body 121 and the support body 122. Further, the pressure applying position at which the pressure Fl is applied is set at substantially the center in the longitudinal direction of the vibrator 101 between the two protruding portions 102a of the elastic body 102. Thereby, the two protruding portions 102a are in pressure contact with the driven body 121 in a well-balanced manner.

[0040] In this way, the respective members are combined and unitized and thereby constitute the vibration motor 100. In this configuration, when the vibrator 101 vibrates and the elliptical motion EM Figure 5C is generated in the protruding portions 102a, a driving force F2 Figure 3 is generated between the protruding portions 102a and the contact surface 121s of the driven body 121. Since the driving force F2 acts in a direction perpendicular to the radial direction passing through the rotational axis P of the driven body 121, the driven body 121 is rotationally driven about the rotational axis P.

[0041] Hereinafter, the vibration mode of the vibrator 101 of the vibration motor 100 will be described using Figure 5A , Figure 5B and Figure 5C .Figure 5A and Figure 5B is a schematic diagram showing a vibration mode of the vibrator 101. Figure 5C is a schematic diagram showing a protruding portion 102a that performs an elliptical motion EM.

[0042] The vibration mode of the vibrator 101 is a complex vibration including a first vibration and a second vibration. As shown in Figure 5A , the first vibration generates a reciprocating motion Ml shown by an arrow in the protruding portion 102a of the vibrator 101, and moves the protruding portion 102a mainly in a tangential direction of the contact surface 121s. In the first vibration, three nodes Nl shown by a broken line appear in the vibrator 101. Two nodes Nl on both end sides in the longitudinal direction of the vibrator 101 are located near the protruding portion 102a.

[0043] As shown in Figure 5B , the second vibration generates a reciprocating motion M2 shown by an arrow in the protruding portion 102a, and moves the protruding portion 102a mainly in a direction of contact / separation with the contact surface 121s. In the second vibration, two nodes N2 shown by a broken line appear in the vibrator 101.

[0044] The first vibration and the second vibration generated at the same frequency generate an elliptical motion EM at a contact point 102c Figure 4 and Figure 5C ) of the protruding portion 102a and the contact surface 121s. Although the vibrator 101 has a plurality of (two) contact points to generate the above-described driving force F2 more greatly, it can have a single contact point. Since details of a method for generating the first vibration and the second vibration are well known as described in the above-mentioned JP 2004-304887 A, detailed description is omitted.

[0045] Hereinafter, the holding mechanism of the rolling ball 108 in the vibration motor 100 will be described with reference to Figure 4 , Figure 6 , Figure 7A and Figure 7B . Further, the relationship between a position at which the support body 122 supports the driven body 121, a position at which the vibrator 101 is in pressure contact with the driven body 121, and a position at which the rolling ball 108 contacts the driven body 121 will be described.

[0046] Figure 6 is an exploded perspective view showing a main part of a configuration that holds the rolling ball 108 between the driven body 121 and the support body 122. Figure 7A and Figure 7B are views that explain the arrangement of the rolling ball 108 viewed from the -Y side.

[0047] Although not shown in Figure 1 , the rolling ball 108 is held by Figure 4The retainer 109 is interposed between the rolling receiving portion 121b of the driven body 121 and the rolling receiving portion 122b of the support body 122. The retainer 109 is a ring-shaped member. An inner periphery 109b of the retainer 109 is rotatably fitted to a retainer fitting portion 122c formed in the support body 122. The retainer 109 has ball holding holes 109a for holding the rolling balls 108. The ball holding holes 109a are arranged at a substantially equal regular interval (60-degree interval) in the circumferential direction. Since the rolling balls 108 are housed in the ball holding holes 109a, the rolling balls 108 are held at a substantially equal interval in the circumferential direction. That is, the retainer 109 is a holding member that holds three or more rolling balls 108 so as to be movable in the circumferential direction around the rotation axis P, in conjunction with the relative rotation of the driven body 121 and the support body 122. The retainer 109 restricts the interval between the three or more rolling balls 108 so that the three or more rolling balls 108 do not come into contact with each other.

[0048] Alternatively, the rolling balls 108 can not be held by the retainer 109 but by a ring-shaped groove. For example, a ring-shaped groove around the rotation axis P is formed in the support body 122. The rolling balls 108 are arranged in the ring-shaped groove. The rolling balls 108 are able to roll with respect to the driven body 121 and the support body 122 in a state where the position of the rolling balls 108 in the radial direction is restricted. Note that the number of the rolling balls 108 is not limited to six. At least three rolling balls 108 are required to maintain rotation stability. That is, the number of the sliding members like the rolling balls 108 is not limited to six. At least three sliding members are required to rotate around the rotation axis P.

[0049] The radius of the rolling track of the rolling ball 108 around the rotation axis P is a revolution radius Rr. The revolution radius Rr is a third distance from the rotation axis P to a third position at which the rolling ball 108 comes into contact with the rolling receiving portion 121b of the driven body 121, in a projection view projected onto a plane perpendicular to the rotation axis P. Since the inner periphery 109b of the retainer 109 is rotatably fitted to the retainer fitting portion 122c of the support body 122, the rolling balls 108 are held in a state where the revolution radius Rr and the interval in the circumferential direction are restricted.

[0050] Note that the center of the retainer fitting portion 122c substantially coincides with the rotation axis P. Further, the diameter of the ball holding hole 109a of the retainer 109 is larger than the diameter of the rolling ball 108, and the thickness of the retainer 109 itself is smaller than the diameter of the rolling ball 108. Therefore, the rolling balls 108 become able to revolve and revolve while maintaining the mutual interval, which makes it possible to be well maintained.

[0051] As described above, the shaft 121a of the driven body 121 is rotatably fitted into the rotation support hole 122a of the support body 122. As Figure 4 , Figure 7A and Figure 7BAs shown, in the projection onto a plane perpendicular to the rotation axis P, the first distance from the rotation axis P to the first position where the shaft 121a is supported radially by the rotation support hole 122a is called the assembly radius Rf. Furthermore, in the projection onto a plane perpendicular to the rotation axis P, the second distance from the rotation axis P to the second position where the protrusion 102a of the vibrator 101 makes pressure contact with the contact surface 121s of the driven body 121 is called the driving radius Rd. This second position is also where the driving force F2 is generated. Figure 3 The position of ).

[0052] The assembly radius Rf is shorter than the drive radius Rd, and the revolution radius Rr is longer than the drive radius Rd. That is, the following relationship is satisfied: assembly radius Rf < drive radius Rd < revolution radius Rr. The engagement between the rotary support hole 122a and the shaft 121a forms a sliding friction part, and the engagement between the ball 108 and the rolling receiving part 121b forms a rolling friction part. The frictional force of the sliding friction part is greater than that of the rolling friction part. That is, the sliding friction part with greater sliding friction is located radially inner to the contact position between the protrusion 102a and the contact point 102c, and the rolling friction part with less sliding friction is located radially outer to the contact position. This prevents the loss of driving force caused by sliding friction from occurring in the driving force loss caused by friction between components during rotary drive.

[0053] Furthermore, since the driving radius Rd is smaller than the revolution radius Rr, and since the contact position between the rolling ball 108 and the rolling receiving part 121b is located outside the contact position between the protrusion 12a and the contact point 102c, the enlargement of the vibration motor 100 is controlled. For example, as Figure 7A As shown, when the outline E of the vibrator 101 is projected onto a plane perpendicular to the rotation axis P, the contact point 102c of the vibrator 101 lies within a circle with a revolution radius Rr, and the outline E partially overlaps with the circle with the revolution radius Rr. That is, at least a portion of the vibrator 101 is arranged side by side with the sliding trajectory (rolling trajectory) of the ball 108 in a direction parallel to the rotation axis P. This avoids radial expansion of the vibration motor 100. In particular, when multiple contact points 102c are provided as in the embodiment to amplify the driving force F2, the outline E of the vibrator 101 tends to increase. However, the above configuration enables a highly space-efficient layout and facilitates miniaturization of the vibration motor 100.

[0054] Furthermore, since the driving radius Rd is smaller than the revolution radius Rr, a stable rotary drive becomes possible. For comparison, this will be explained... Figure 4the contact point 1020c of the vibrator 101 and the rolling ball 1080. A virtual case is considered. In the virtual case, the vibration motor 100 is set so that the contact point 1020c of the vibrator 101 will coincide with the position of the revolution radius Rr and the rolling ball 1080 is set at the position of the drive radius Rd. In the virtual case, the rolling ball 1080 always revolves radially inside the contact point 1020c of the vibrator 101. Therefore, for example, when pressure is applied to the contact point 1020c, tilting Θ around the rolling ball 1080 can occur.

[0055] When the tilting prevention mechanism is provided in the area A( Figure 4 ) opposite the contact point 1020c across the rotation axis P as explained in JP 2006-158054 A to cancel the tilting Θ, the motor size will be enlarged and the cost will be increased. In the present embodiment, the above tilting Θ is prevented by providing the rolling ball 108 outside the contact point 102c, which enables stable rotation drive.

[0056] Even if the rolling ball 108 is at any rotation phase by revolution of the rolling ball 108, a certain condition must be satisfied to prevent tilting Θ around the rolling ball 108. The preferable positional relationship of the rolling ball 108 and the vibrator 101 is explained.

[0057] First, as shown in Figure 7A , a case where the rolling balls 108a to 108f are arranged at equal intervals (60-degree intervals) in the circumferential direction is considered. The midpoint of the contact point 102c of the protrusion portion 102a to the contact surface 121s of the driven body 121 by the pressing mechanism is defined as a pressing position f. The pressing position f is located approximately on the circle of the drive radius Rd. In a projection view projected onto a plane perpendicular to the rotation axis P, a polygon SI obtained by connecting the centers of the rolling balls 108 and an inscribed circle CI of the polygon SI are defined. The contact point 102c of the vibrator 101 and the pressing position f are located inside the inscribed circle CI of the polygon SI. When the above positional relationship is satisfied, even if the rolling ball 108 is at any rotation phase, the contact point 102c and the pressing position f are always located in at least one of the triangles obtained by connecting the centers of the rolling balls 108.

[0058] For example, in the state of Fig. 7, the contact point 102c and the pressing position f are located in the triangle abc obtained by connecting the centers of the rolling balls 108a, 108b, and 108c. Figure 7B The rotation phase of the rolling ball 108 obtained by revolving the rolling ball 108 around the rotation axis P by 30 degrees from the state shown in Figure 7A is shown. In addition, the rotation phase of the rolling ball 108 obtained by revolving the rolling ball 108 around the rotation axis P by 60 degrees from the state shown in Figure 7BIn the illustrated state, the contact point 102c of the vibrator 101 and the pressing position f are located in the triangle abc obtained by connecting the centers of the rolling balls 108a, 108b, and 108c.

[0059] In this way, since the pressure is supported by the three points a, b, and c, it is possible to prevent the occurrence of the inclination θ described above. When the positional relationship described above is satisfied, a similar effect can be obtained even if the rolling ball 108 is in any rotational phase. Incidentally, in the example illustrated in Figure 7B In the example illustrated, the pressing position f is located not only in the triangle abc but also in the triangle bcd obtained by connecting the centers of the rolling balls 108b, 108c, and 108d. Note that at least the pressing position f should be located inside the circle Cl that is the incircle of the polygon SI obtained by connecting the centers of the rolling balls 108. It is not indispensable that the adjacent rolling balls 108 form a triangle. In other words, it is sufficient that there are three rolling balls 108 such that the pressing position f will be located inside a triangle obtained by connecting the centers of the three rolling balls 108. Further, when viewed in the Y direction, the contact point 102c of the protruding portion 102a that contacts the contact surface (contact portion) 121s should be located in any one of one or more triangular regions formed by connecting any three of the rolling balls (support members) 108 with straight lines.

[0060] Although in the example illustrated in Figure 6 , Figure 7A and Figure 7B the rolling balls 108 are arranged at equal intervals (60-degree intervals) in the circumferential direction around the rotational axis P, the rolling balls 108 do not necessarily have to be arranged at equal intervals. A modified example in which the rolling balls 108 are arranged at unequal intervals will be described with reference to Figure 8A and Figure 8B .

[0061] Figure 8A and Figure 8B are views that illustrate the arrangement of the rolling balls 108 viewed from the -Y side. In the example illustrated in Figure 8A , the rolling ball 108b is arranged at a position that is displaced by 10 degrees in the circumferential direction from an equal-interval position (60-degree position). Figure 7A The contact point 102c and the pressing position f are arranged so as to be located inside the circle C2 that is in contact with the edge bc closest to the rotational axis P among the edges of the polygon obtained by connecting the centers of the rolling balls 108 and that is centered on the rotational axis P.

[0062] When the positional relationship described above is satisfied, the contact point 102c of the vibrator 101 and the pressing position f are always located in at least one of the triangles obtained by connecting the centers of the rolling balls 108 even if the rolling ball 108 is in any rotational phase. Further, in Figure 8AIn the illustrated state, the contact point 102c and the pressing position f are located in a triangle abc obtained by connecting the centers of the rolling balls 108a, 108b, and 108c. In this way, since the pressure is supported by the three points a, b, and c, occurrence of the inclination θ described above can be prevented.

[0063] Figure 8B The rotation phase of the rolling ball 108 obtained by causing the rolling ball 108 to revolve 25 degrees around the rotation axis P from the state illustrated in FIG. 10 is illustrated in FIG. 11. In addition, in the example illustrated in FIG. 11, the pressing position f is located in the triangle abc obtained by connecting the centers of the rolling balls 108a, 108b, and 108c. Figure 8A The rotation phase of the rolling ball 108 obtained by causing the rolling ball 108 to revolve 25 degrees around the rotation axis P from the state illustrated in FIG. 10 is illustrated in FIG. 11. In addition, in the example illustrated in FIG. 11, the pressing position f is located in the triangle abc obtained by connecting the centers of the rolling balls 108a, 108b, and 108c. Figure 8B In the illustrated state, the contact point 102c and the pressing position f are located in a triangle abc obtained by connecting the centers of the rolling balls 108a, 108b, and 108c. In this way, since the pressure is supported by the three points a, b, and c, occurrence of the inclination θ described above can be prevented. When the above-described positional relationship is satisfied, a similar effect can be obtained even if the rolling ball 108 is in any rotation phase. Incidentally, in the example illustrated in FIG. 10, the pressing position f is located not only in the triangle abc but also in a triangle bcd obtained by connecting the centers of the rolling balls 108b, 108c, and 108d. Figure 8B In the example illustrated in FIG. 10, the pressing position f is located not only in the triangle abc but also in a triangle bcd obtained by connecting the centers of the rolling balls 108b, 108c, and 108d.

[0064] It should be noted that at least the pressing position f should be located within a circle C2 which contacts an edge of a polygon obtained by connecting the centers of the rolling balls 108 closest to the rotation axis P and which is centered on the rotation axis P.

[0065] According to the present embodiment, in a projection diagram projected onto a plane perpendicular to the rotation axis P, the fitting radius Rf is smaller than the driving radius Rd, and the revolving radius Rr is longer than the driving radius Rd. Thereby, since the driving force loss due to sliding friction is reduced, the driving load can be reduced. Furthermore, since unlike the configuration in JP 2006-158054 A, high machining precision for making the diameters of the V-shaped grooves uniform and eliminating eccentricity is not required, the configuration is simple and a cost increase is prevented. Thus, it is possible to provide a vibration-type driving device which realizes low cost and high precision while reducing the driving load.

[0066] Furthermore, the pressing position f is located within a circle C2 which contacts an edge of a polygon obtained by connecting the centers of the rolling balls 108 closest to the rotation axis P and which is centered on the rotation axis P. This condition is satisfied in the example illustrated in FIG. 10 and the example illustrated in FIG. 11. Figure 7A and Figure 7B the example illustrated in FIG. 10 and the example illustrated in FIG. 11. Figure 8A and Figure 8B the example illustrated in FIG. 10 and the example illustrated in FIG. 11. Figure 7A and Figure 7B), the pressing position f is located inside a circle Cl that is the incircle of a polygon Sl obtained by connecting the centers of the balls 108. This condition is satisfied in the example shown in Figure 7A and Figure 7B . These configurations prevent the occurrence of the tilt θ and enable stable rotational drive. Furthermore, since a tilt prevention mechanism is not required, downsizing is facilitated.

[0067] The configuration of the driven body 121 will be described in detail below with reference to Figure 9A , Figure 9B and Figure 10 . Figure 9A and Figure 9B are exploded perspective views showing the driven body 121. Figure 10 is a cross-sectional view showing the main part of the vibration motor 100 and the driven body 121 in detail.

[0068] The driven body 121 is schematically shown in a simplified form in Figure 2 , Figure 3 and Figure 4 . As shown in Figure 9A and Figure 9B , the driven body 121 constituting the first unit has a shaft (base member) 121a, a rolling receiving portion (second member) 121b, a friction member (first member) 201, a spacer 202, a damping member 203, and a connecting member 204. In Figure 9A , Figure 9B and Figure 10 , the members constituting the driven body 121 are shown separately.

[0069] Although not shown in Figure 10 , a holder 109 that holds the balls 108, as shown in Figure 6 , is interposed between the rolling receiving portion 121b of the driven body 121 and the rolling receiving portion 122b of the support body 122.

[0070] The friction member 201 is a ring-shaped member having a contact surface 121s. The spacer 202 and the rolling receiving portion 121b are interposed between the friction member 201 and the shaft 121a in this order from the friction member 201 side. Furthermore, the damping member 203 is sandwiched between the friction member 201 and the rolling receiving portion 121b so as to surround the spacer 202. Six through-holes are formed in each of the friction member 201, the spacer 202, and the rolling receiving portion 121b for the six connecting members (six fixing members) 204 to pass through, respectively. The holes of the friction member 201 are fixing portions 201a. The positions of the fixing portions 201a of the friction member 201 in the radial direction R are common to each other. The six fixing portions 201a are arranged at substantially equal intervals. The number is not critical. Six screw holes for fastening the six connecting members 204, respectively, are formed in the shaft (base member) 121a.

[0071] The friction member 201 is fixed to the shaft 121a using the connecting member 204. The spacer 202 and the rolling receiving portion 121b are also fixed to the shaft 121a together with the friction member 201 using the connecting member 204 (in a jointly fastened state). With this configuration, the shaft 121a, as a base member, holds the friction member 201. Furthermore, the rolling receiving portion 121b, as a pressure receiving member, receives pressure F1 from the vibrator 101, which is generated by a pressurizing mechanism between the friction member 201 and the rolling receiving portion 122b of the support body 122. The spacer 202 has higher rigidity than the friction member 201.

[0072] like Figure 10 As shown, the radial direction R starts at the rotation axis P and intersects the rotation axis P perpendicularly. Furthermore, in the projection onto a plane perpendicular to the rotation axis P (i.e., on the radial direction R), the second distance from the rotation axis P to the second position where the protrusion 102a of the vibrator 101 makes pressure contact with the contact surface 121s of the driven body 121 is called the driving radius Rd. This second position is also where the driving force F2 is generated. Figure 3 The position of the friction member 201 and the rolling receiving part 121b is also mentioned. Furthermore, the distance from the rotation axis P to the fourth position where the friction member 201 and the rolling receiving part 121b are jointly fixed to the shaft 121a in the radial direction R is called the fixed position radius Rx. The fixed position radius Rx is smaller than the driving radius Rd.

[0073] Since the rolling receiving portion 121b and the friction member 201 are fixed together using the connecting member 204, radial expansion is avoided compared to a configuration where the rolling receiving portion 121b and the friction member 201 are fixed separately. If only radial expansion is to be prevented, a method can be considered where the fixed position of the friction member 201 is shifted circumferentially from the fixed position of the rolling receiving portion 121b around the rotation axis P. For example, each member can be fixed at three points at 120-degree intervals, and the fixed points of the members can be offset by 60 degrees from each other.

[0074] However, according to this method, the shape of the friction member 201 would become an asymmetrical and strange shape around the rotation axis P, which would produce unwanted resonance. Since the fixed position of the rolling receiving portion 121b is the same as the fixed position of the friction member 201 in this embodiment, the friction member 201 will not become an asymmetrical and strange shape and will become a shape that produces almost no unwanted resonance. Furthermore, neither the rolling receiving portion 121b nor the friction member 201 will become an asymmetrical and strange shape. Because the rolling receiving portion 121b will not become an asymmetrical and strange shape, almost no unwanted resonance will occur in the rolling receiving portion 121b caused by vibrations propagating from the friction member 201 through the spacer 202.

[0075] The circle of the fixed position radius Rx is adjacent to and close to the circle of the drive radius Rd. In a projection view projected to a plane perpendicular to the rotation axis P, the position at which the friction member 201 and the rolling receiving portion 121b sandwich the damping member 203 overlaps the circle of the drive radius Rd. In other words, the friction member 201 and the rolling receiving portion 121b sandwich the damping member 203 in the region of the circle of the drive radius Rd in the radial direction R.

[0076] In the present embodiment, the friction member 201 and the rolling receiving portion 121b are fixed together to the shaft 121a at the fourth position by the connecting member 204, the fourth position being on the circle of the fixed position radius Rx, inside the second position on the circle of the drive radius Rd. First, it is possible to dampen the vibration by fixing the friction member 201 to the shaft 121a by the connecting member 204. As a result, unnecessary resonance of the friction member 201 is reduced and the drive performance is improved.

[0077] Furthermore, since the position of the fixed portion 201a is inside the second position at which the vibrator 101 contacts the friction member 201, it is possible to hold and fix the friction member 201 at a position close to the center of mass of the driven body 121, and it is possible to suppress the moment of inertia of the entire driven body 121 to be small. As a result, the drive performance is improved. Furthermore, since the rolling receiving portion 121b and the friction member 201 are fixed together to the shaft 121a, compared to a configuration in which the rolling receiving portion 121b and the friction member 201 are fixed separately, expansion in the radial direction R is avoided. Furthermore, it is possible to prevent the friction member 201 from becoming an odd shape, and unnecessary resonance of the friction member 201 is reduced. Thus, it is possible to control expansion while ensuring good drive performance.

[0078] In particular, since the connecting member 204 fixes the friction member 201 and the rolling receiving portion 121b together at a concentric position around the rotation axis P, space in the radial direction R is saved.

[0079] Furthermore, the friction member 201 and the rolling receiving portion 121b sandwich the damping member 203 in the region of the circle of the drive radius Rd in the radial direction R. Thereby, it is possible to further dampen unnecessary resonance of the friction member 201, and expansion is not caused.

[0080] Furthermore, since the circle of the fixed position radius Rx is adjacent to and close to the circle of the drive radius Rd in the radial direction R, when the friction member 201 is considered as a beam elongated in the radial direction R, it is possible to shorten the length of the beam. As a result, this contributes to control of unnecessary resonance of the friction member 201. Furthermore, from this point of view, when the difference between the fixed position radius Rx and the drive radius Rd is sufficiently short, the effect of resonance control is obtained.

[0081] Further, a spacer 202 having rigidity higher than that of the friction member 201 is interposed between the friction member 201 and the rolling receiving portion 121b. Thereby, the damping effect obtained by fixing the friction member 201 can be improved.

[0082] Next, the second embodiment will be described. Figure 11 is an exploded perspective view showing a main part of a mechanism for holding the rolling ball 108 between the driven body 121 and the support body 122 in the second embodiment of the present application. Figure 12A and Figure 12B is a view showing the arrangement of the rolling ball 108 as viewed from the -Y side.

[0083] In the present embodiment, the number of the rolling balls 108 and the holding mechanism of the rolling balls 108 are different from those of the first embodiment, and the other structures are the same as those of the first embodiment. Figure 11 and Figure 12B correspond to Figure 6 and Figure 7A , respectively.

[0084] The vibration motor 100 of the present embodiment does not have the holder 109. The rolling balls 108 are held only by the support body 122 and the driven body 121. Specifically, an annular groove G is formed in the support body 122. The annular groove G is constituted by a rolling receiving portion 122b and a pair of side walls 122e. The rolling balls 108 are arranged in the annular groove G. The center of the annular groove G substantially coincides with the rotation axis P. In the radial direction R, the distance from the rotation axis P to the center position of the annular groove G is equal to the revolution radius Rr. Therefore, the rolling balls 108 can roll with respect to the driven body 121 and the support body 122 in a state where the position of the rolling balls 108 in the radial direction is constrained.

[0085] Since the rolling balls 108 are arranged in the annular groove G with an appropriate backlash in the circumferential direction and the radial direction, the rolling balls 108 can revolve and orbit while maintaining the mutual spacing between the rolling balls 108 substantially constant, which makes it possible to maintain rotation well. The relationship between the drive radius Rd, the fitting radius Rf, and the revolution radius Rr is the same as that of the first embodiment. Further, the relationship between the outline E of the vibrator 101 and the revolution radius Rr is the same as that of the first embodiment ( Figure 12A and Figure 12B ). Note that the annular groove G is formed in the support body 122 which is one of the driven body 121 and the support body 122. This is different from the configuration in JP 2006-158054 A described above in which V-shaped grooves are formed on both sides. Therefore, since high machining precision is not required, the configuration is simple and an increase in cost is prevented. When the groove is not a V-shaped groove, the annular groove G can be formed in both the driven body 121 and the support body 122.

[0086] According to the present embodiment, the same effects as those of the first embodiment are obtained with respect to providing a low-cost and high-precision vibration-type drive device while reducing a driving load.

[0087] Although the example of driving the rotating image pickup device 21 by the vibration motor 100 is described in each of the above-described embodiments, the present application can be applied to a device having a movable body that is rotated by the vibration motor 100. For example, a laser irradiation device, an arm unit of a robot arm, and the like correspond to the movable body in this case.

[0088] In each of the embodiments, the words with the modifier "approximately" or "substantially" do not exclude exact matches. For example, "approximately equal intervals", "approximately coincides", "approximately constant", "approximately center", "approximately ring type", and "approximately equal" include "equal intervals", "coincides", "constant", "center", "ring", and "equal", respectively.

[0089] Other Embodiments

[0090] While the present application has been described with reference to exemplary embodiments, it is to be understood that the application is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0091] This application claims the benefit of Japanese Patent Applications Nos. 2020-145845 and 2020-145846, filed August 31, 2020, which are hereby incorporated by reference herein in their entirety.

Claims

1. A vibration-type drive device, comprising: A drive unit having a vibrator with protrusions and configured to generate a driving force by vibrating the vibrator. The first unit has a contact portion, and the protrusion is in pressure contact with the contact portion in a first direction; The second unit is configured to rotate relative to the first unit about a predetermined rotation axis parallel to the first direction by the driving force of the driving unit. and Three or more support members are located between the first unit and the second unit in the first direction and are configured to support the first unit and the second unit so as to be rotatable relative to each other. The support member is positioned such that, during relative rotation of the first unit and the second unit, when viewed along the first direction, the contact point where the protrusion contacts the contact portion is always located in at least one of the triangular regions formed by connecting any three of the three or more support members with a straight line.

2. The vibration-type drive device according to claim 1, wherein, During the relative rotation of the first and second units, when viewed along the first direction, the contact point will not coincide with any of the three or more support members.

3. The vibration-type drive device according to claim 1 further includes a retaining member that retains the three or more support members so that they can move circumferentially along the predetermined axis of rotation as the first unit and the second unit rotate relative to each other.

4. The vibration-type drive device according to claim 3, wherein, The retaining member is configured to constrain the spacing between the three or more support members so that the three or more support members do not come into contact with each other.

5. The vibration-type drive device according to claim 1, wherein, The first unit has a first member having the contact portion, a second member in contact with the three or more support members, and an attenuation member between the first member and the second member.

6. The vibration-type drive device according to claim 5, wherein, The first unit has a fixing member for fixing the first component, the second component and the attenuation component to the base component.

7. The vibration-type drive device according to claim 6, wherein, In a plane perpendicular to the first direction, the distance between the predetermined axis of rotation and the fixed member is shorter than the distance between the predetermined axis of rotation and the protrusion.

8. A camera device, comprising: A drive unit having a vibrator with protrusions and configured to generate a driving force by vibrating the vibrator. The first unit has a contact portion, and the protrusion is in pressure contact with the contact portion in a first direction; The second unit is configured to rotate relative to the first unit about a predetermined rotation axis parallel to the first direction by the driving force of the driving unit. and Three or more support members are located between the first unit and the second unit in the first direction, and are configured to support the first unit and the second unit so as to be rotatable relative to each other. The camera unit's camera direction changes according to the relative rotation of the first unit and the second unit. The support member is positioned such that, during relative rotation of the first unit and the second unit, when viewed along the first direction, the contact point where the protrusion contacts the contact portion is always located in at least one of the triangular regions formed by connecting any three of the three or more support members with a straight line.

9. The camera device according to claim 8, wherein, During the relative rotation of the first unit and the second unit, when viewed along the first direction, the contact point will not coincide with any of the three or more support members.

10. The camera device according to claim 8, further comprising a retaining member that retains the three or more support members so as to be movable circumferentially along the predetermined axis of rotation as the first unit and the second unit rotate relative to each other.

11. The camera device according to claim 10, wherein, The retaining member is configured to constrain the spacing between the three or more support members so that the three or more support members do not come into contact with each other.

12. The camera device according to claim 8, wherein, The first unit has a first member having a contact portion, a second member in contact with the three or more support members, and an attenuation member between the first member and the second member.

13. The camera device according to claim 12, wherein, The first unit has a fixing member for fixing the first component, the second component and the attenuation component to the base component.

14. The camera device according to claim 13, wherein, In a plane perpendicular to the first direction, the distance between the predetermined axis of rotation and the fixed member is shorter than the distance between the predetermined axis of rotation and the protrusion.

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