Vibration drive device and image acquisition device that uses this

Abstract

A vibration drive device comprising: a drive unit having a vibrator provided with a projection and designed to generate a driving force by vibrating the vibrator; a first unit having a contact section with which the projection is in pressure contact in a first direction; a second unit designed to rotate about a predetermined axis of rotation parallel to the first direction by the driving force of the drive unit relative to the first unit;and at least three support elements between the first unit and the second unit in the first direction, designed to support the first unit and the second unit so that they are relatively rotatable, the support elements being positioned such that, during a relative rotation of the first unit and the second unit, a point of contact where the projection touches the contact section, viewed in the first direction, is always located in at least one triangular region of one or more triangular regions formed by connecting any three support elements from the at least three support elements with straight lines.

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The invention relates to a vibration drive device that generates a rotary drive force through vibration and frictional force, and an image acquisition device that uses this. Description of the state of the art

[0002] Some conventional electronic devices, such as image recording devices, employ a vibration drive device that generates a rotary driving force through excited vibration and friction. A rotary ultrasonic motor characterized by compact size, high output power, and quiet operation is known as a vibration drive device. Japanese published patent (Kokai) No. 2018-189745 (JP 2018-189745 A) discloses an ultrasonic motor employing a ring-type vibrator. Japanese published patent (Kokai) No. 2006-158054 (JP 2006-158054 A) and Japanese published patent (Kokai) No. 2004-304887 (JP 2004-304887 A) disclose ultrasonic motors employing a blade-type vibrator.For example, when an ultrasonic motor is used to drive the lens of a camera, a vibrator is in contact with a friction component that is connected to a lens frame. The lens frame is then driven to rotate by transmitting an elliptical motion generated by the vibrator to the friction component.

[0003] This results in a loss of driving force due to sliding friction, which in turn leads to a loss of pushing force, since a drive unit of a vibratory drive device drives a driven unit while constantly receiving a pushing force. Accordingly, JP 2018-189745 A and JP 2006-158054 A disclose designs that receive the pushing force through rolling elements, such as balls, in order to reduce such a loss of driving force due to sliding friction.

[0004] However, the sliding friction that causes the loss of driving force also occurs in a radial direction. For example, the design of JP 2018-189745 A supports a rotary cylinder, which is subjected to axial pressure, with rollers arranged circumferentially and prevents wobbling during rotation in the radial direction by fitting a projection, formed on an end face in the axial direction of the rotary cylinder, into the inner surfaces of the respective rollers. According to this design, the loss of driving force also occurs at this point, since the sliding friction in the fitting occurs in the radial direction of the rotary cylinder.Furthermore, the loss at the fitting significantly impacts the loss of driving force, as the projection of the rotary cylinder is fitted into the inner surfaces of the rollers at a position further outward than where the vibrator is in radial contact. Consequently, there is room for improvement regarding the reduction of drive load.

[0005] Furthermore, the design of JP 2006-158054 A supports a rotary cylinder subjected to axial pressure by clamping balls between V-grooves provided along the circumferences of a rotor body and a bearing holder, thus preventing radial wobble during rotary operation. Since this design supports the rotary cylinder through rolling friction in both the axial and radial directions, the loss of driving force is reduced. However, extremely high machining accuracy is required to ensure the V-groove diameters match and to eliminate any misalignment, which increases costs. Consequently, it is challenging to achieve both cost reduction and maintain high machining accuracy.

[0006] Furthermore, both JP 2006-158054 A and JP 2004-304887 A propose a vibration motor designed such that a relatively small vibrator is in contact with an annular friction element only at a specific position on the circumference of the friction element. Such a vibration motor is advantageous for miniaturization because the vibrator is small.

[0007] However, the friction component tends to generate unnecessary resonance due to limited regulation, as it is only regulated in a specific position around the circumference. This can impede the vibrator's driving force and reduce the vibration motor's power output. While the friction component can be fixed to a stationary component with screws to prevent unwanted resonance, simply fixing it without further measures can still generate unwanted resonance or even increase the overall size of the unit. SUMMARY OF THE INVENTION

[0008] The invention provides a vibration drive device that achieves low cost and high accuracy while reducing drive load.

[0009] Accordingly, the invention provides a vibration drive device comprising a drive unit having a vibrator provided with a projection and designed to generate a driving force by vibrating the vibrator, a first unit having a contact section with which the projection is in pressure contact in a first direction, a second unit designed to rotate about a predetermined axis of rotation parallel to the first direction by the driving force of the drive unit, and at least three support components between the first unit and the second unit in the first direction, designed to support the first unit and the second unit so that they are rotatable relative to each other.The support components are positioned such that, during a relative rotation of the first unit and the second unit, a point of contact where the projection touches the contact section is always located in at least one triangular area of ​​one or more triangular areas when viewed in the first direction, which is formed by connecting any three support components from the at least three support components with straight lines.

[0010] According to the invention, a vibration drive device can be provided that achieves low cost and high accuracy while reducing drive load.

[0011] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. List of characters Fig. Figure 1 is a schematic view showing an electronic device in which a vibration motor is used as a vibration drive device according to a first embodiment of the invention. Fig. Figure 2 is a perspective exploded view showing the vibration motor. Fig. Figure 3 is a perspective exploded view showing the vibration motor. Fig. Figure 4 is a sectional view showing a main part of the vibration motor including a driven body, shown in a simplified form. Fig. 5A and Fig. 5B are schematic views showing a vibration mode of a vibrator enclosed in the vibration motor, and Fig. 5C is a schematic view showing a projection of the vibrator performing an elliptical motion. Fig. Figure 6 is a perspective exploded view showing a major part of a design holding rolling balls enclosed within the vibration motor. Fig. 7A and Fig. 7B are views that describe an arrangement of the rolling balls as seen from a -Y side. Fig. 8A and Fig. 8B are views that describe the arrangement of the rolling balls as seen from the - Y side. Fig. 9A and Fig. Figure 9B are perspective exploded views showing the driven body enclosed in the vibration motor. Fig. Figure 10 is a sectional view showing the main part of the vibration motor and the driven body, which is shown in detail. Fig. Figure 11 is a perspective exploded view of a main part of a design holding rolling balls which are included in a vibration motor as a vibration drive device according to a second embodiment of the invention. Fig. Figure 12 is a view that describes an arrangement of the rolling balls as seen from the -Y side. DESCRIPTION OF THE EXECUTION FORMS

[0012] The embodiments according to the invention are described in detail below with reference to the drawings.

[0013] Fig. Figure 1 is a schematic view showing an electronic device in which a vibration motor is used as a vibration drive device according to a first embodiment of the invention. A rotary drive device 1 is an example of this electronic device. The rotary drive device 1 comprises a fixed body 10 and a movable body 20 that rotates relative to the fixed body 10. The fixed body 10 includes a control substrate (not shown) that controls the entire rotary drive device 1, in addition to the vibration motor 100, which is shown as the vibration drive device. The vibration motor 100 is shown in a sectional view. The movable body 20 includes an image acquisition device 21, which is an image acquisition unit capable of capturing an image of an object. It should be noted that the entire rotary drive device 1 can be referred to as the image acquisition device.

[0014] The vibration motor 100 is a rotary ultrasonic motor equipped with a vibrator 101 (referred to later as such) that rotates the 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 rotates the driven body 121, the movable body 20, which includes the image-capturing device 21, rotates about an axis of rotation P that passes through a center of rotation. The image-capturing direction of the image-capturing device 21 changes because the movable body 20 rotates.

[0015] The rotary drive device 1 is designed 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. Alternatively, the rotary drive device 1 can be designed to be used in a state where the rotatable body 20 is connected to the support body 122 and the driven body 121 is fixed.

[0016] Fig. 2 and Fig. Figure 3 are perspective exploded views showing the vibration motor 100. Fig. Figure 4 is a sectional view showing a main part of the vibration motor 100, which includes the driven body 121, shown in a simplified form.

[0017] The directions of components are described below by reference to the X, Y, and Z coordinate axes, which are in Fig. 2, Fig. Figures 3, etc., are shown. A direction parallel to the axis of rotation P is defined as a Y-direction in this embodiment. In particular, the side on which the driven body 121 is located with respect to the vibrator 101 is a +Y-side in the Y-direction. A longitudinal direction of the vibrator 101 that coincides with a tangential direction of the driven body 121 is defined as a Z-direction. A direction that intersects both the Y-direction and the Z-direction perpendicularly is defined as an X-direction.

[0018] The vibratory motor 100 mainly comprises the driven body 121, which forms a first unit, the support body 122, which forms a second unit, and a chassis 122d. The support body 122 holds the entire vibratory motor 100. The driven body 121 is formed as a whole in an approximately ring shape. The driven body 121 has a shaft 121a, a rolling receiving section 121b, and a contact surface (a contact section) 121s. The contact surface 121s is a friction surface. A rotary support hole 122a is formed in the support body 122. The shaft 121a of the driven body 121 is rotatably fitted into the rotary support hole 122a. This allows the entire driven body 121 to rotate about the axis of rotation P relative to the support body 122. Accordingly, the support structure of the vibration motor 100 in the radial direction is a sliding bearing structure.

[0019] Since the vibration motor 100 has a simple design that defines a radial fit relationship through the rotary support hole 122a and the shaft 121a, a high degree of fit is easily ensured at relatively low cost. It should be noted that the driven body 121 can be formed from a single component or from separate components comprising the shaft 121a and a disk component that includes the contact surface 121s and a rolling receiving section 121b. Alternatively, the relationship between the shaft 121a and the rotary support hole 122a can be reversed. That is, a shaft provided in the support body 122 can be fitted into a rotary support hole provided in the driven body 121, so that the entire driven body 121 is rotatable relative to the support body 122.

[0020] The vibrator 101, as a component of a drive unit, has an elastic body 102 and a piezoelectric device 103. The piezoelectric device 103 is an electromechanical energy conversion element that excites a vibration in the elastic body 102. The piezoelectric device 103 is made, for example, of PZT (lead zirconate titanate). The elastic body 102 consists of a metal plate made of stainless steel, etc.

[0021] The elastic body 102 has two projections 102a that are aligned in the longitudinal direction, and restrained sections 102b ( Fig. 2) The elastic body 102 and the piezoelectric device 103 are adhered with adhesive, etc. The projections 102a are in pressure contact with the contact surface 121s, since the piezoelectric device 103 is pressed into a state in which the elastic body 102 and the piezoelectric device 103 are adhered by a subsequently mentioned pressure-applying mechanism. An elliptical motion EM ( Fig. 5C) occurs in each of the projections 102a of the elastic body 102 by a vibration (ultrasonic vibration) of a frequency within an ultrasonic range, which is caused by applying a driving voltage of a high-frequency alternating current to the piezoelectric device 103. As a result, a driving force occurs between the projections 102a and the contact surface 121s. A driving force F2, mentioned later ( Fig. 3) occurs at a position where the projection 102a touches the contact surface 121s.

[0022] A rolling receiving section 122b, which faces the rolling receiving section 121b of the driven body 121, is formed in the support body 122. Rolling balls (six pieces in Fig. 2) 108 are provided between the rolling bearing sections 121b and 122b. That is, a support structure around the axial direction of the vibration motor 100 is a rolling bearing structure and the drive body 121 and the support body 122 are freely rotatable relative to each other by rotations of the rolling balls 108.

[0023] This allows the frictional resistance caused when the driven body 121 moves while receiving the pressure force to be minimized.

[0024] Although the rolling receiving section 122b and the support body 122 can be formed by a single component, they can also be formed by separate components. Furthermore, although the rolling receiving section 121b and the driven body 121 can be formed by a single component, they can also be formed by separate components. It should be noted that rolling elements, such as rollers, or sliding elements can be provided between the rolling receiving section 122b and the rolling receiving section 121b instead of the rolling balls 108.

[0025] A first holder 104 holds the elastic body 102 in a fixed position by holding the sections 102b of the elastic body 102. This causes the vibrator 101 to move together with the first holder 104. The chassis 122d is fixed to the support body 122. A frame component 113 holds the first holder 104 by means of an elastic connecting component 114. The first holder 104 is positioned and fixed to the driven body 121 by fixing the frame component 113 to the chassis 122d with screws 115.

[0026] An interrupting component 105 has the function of interrupting the transmission of vibration to other components. The interrupting component 105 interrupts the transmission of the ultrasonic vibration from the piezoelectric device 103 to a small base 106 (referred to later), but does not dampen the ultrasonic vibration of the piezoelectric device 103. A fur fabric is suitable as a material for the interrupting component 105. The small base 106 is in surface contact with the piezoelectric device 103 by means of the interrupting component 105 and has the function of transmitting the compressive force from a compression spring 111 to the piezoelectric device 103.

[0027] The pressurization mechanism comprises a pressure component 110, the pressurization spring 111 (a pressurization device), and a receiving component 112. A second bracket 107 holds this pressurization mechanism. The second bracket 107 is fixed to the chassis 122d with two screws 115, together with the frame component 113. A fitting hole 112a, a circular hole, is formed in the center of the receiving component 112. A threaded section 112b is formed on an outer circumferential surface of the receiving component 112. The receiving component 112 is fixed to the second bracket 107 by screwing the threaded section 112b into the screw hole 107a of the second bracket 107. Furthermore, the fitting hole 112a engages with and holds a fitting shaft 110a of the pressure component 110.The pressure component 110 is fitted into the fitting hole 112a of the receiving component 112 and is held movable only in one direction, which is approximately vertical to the contact surface 121s of the driven body 121.

[0028] The pressure component 110 transmits the pressure force from the compression spring 111 to the vibrator 101 by means of the small base 106 and the interruption component 105. This brings the vibrator 101 into contact with the driven body 121. The compression spring 111 consists, for example, of a compression spring. One end of the compression spring 111 is fixed to the receiving body 112, and the other end rests against the pressure component 110. In this way, the compression spring 111 generates the pressure force F1 by fixing both ends in a compressed state. The generated pressure force F1 is transmitted to the piezoelectric device 103 as a force in a direction (+Y-direction) perpendicular to the contact surface 121s of the driven body 121. The vibrator 101 is in contact with the driven body 121 due to the pressure force F1.Accordingly, the +Y direction is a direction of pressure application by the pressure spring 111. The rolling balls 108 are examples of sliding components that receive the pressure force F1 between the driven body 121 and the support body 122. Furthermore, a pressure position at which the pressure force F1 is applied is set at an approximate midpoint between the two projections 102a of the elastic body 102 in the longitudinal direction of the vibrator 101. This ensures that the two projections 102a are in good equilibrium in pressure contact with the driven body 121.

[0029] In this way, the respective components are incorporated and modularized, resulting in the formation of the vibration motor 100. In this configuration, when the vibrator 101 vibrates and the elliptical motion EM ( Fig. 5C) occurs in the projections 102a, the driving force F2 ( Fig. 3) between the projections 102a and the contact surface 121s of the driven body 121. Since the driving force F2 acts in the direction that is perpendicular to the radial direction passing through the axis of rotation P of the driven body 121, the driven body 121 is driven to rotate about the axis of rotation P.

[0030] Next, a vibration mode of the vibrator 101 of the vibration motor 100 will be used. Fig. 5A, Fig. 5B and Fig. 5C described. Fig. 5A and Fig. Figure 5B shows schematic views illustrating the vibration mode of the Vibrator 101. Fig. 5C is a schematic view showing the projection 102a performing the elliptical motion EM.

[0031] The vibration mode of the Vibrator 101 is a complex vibration that includes a first vibration and a second vibration. As in Fig. As shown in Figure 5A, the first vibration generates reciprocating movements M1, indicated by arrows, in the projections 102a of the vibrator 101 and displaces the projection 102a mainly in the tangential direction of the contact surface 121s. During the first vibration, three nodes N1, indicated by dashed lines, occur in the vibrator 101. Two nodes N1 at both end faces in the longitudinal direction of the vibrator 101 are located close to the projections 102a.

[0032] As in Fig. As shown in Figure 5B, the second vibration generates reciprocating movements M2, indicated by arrows, in the projections 102a and displaces the projections 102a mainly in one direction to touch / separate from the contact surface 121s. During the second vibration, two nodes N2, indicated by dashed lines, occur in the vibrator 101.

[0033] The first and second vibrations, generated at the same frequency, cause the elliptical movements EM at contact points 102c ( Fig. 4 and Fig. 5C) of the projections 102a with the contact surface 121s. Although the vibrator 101 has a plurality (two) contact points to generate the aforementioned driving force F2 more strongly, it may have a single contact point. Since details of a method for generating the first and second vibrations, as described in the aforementioned JP 2004-304887 A, are well known, detailed descriptions have been omitted.

[0034] Next, a holding mechanism for the rolling balls 108 in the vibration motor 100 is described with reference to Fig. 4, Fig. 6, Fig. 7A and Fig. 7B is described. In addition, a relationship is described between the position at which the support body 122 supports the driven body 121, the position at which the vibrator 101 is in pressure contact with the driven body 121, and the position at which the rolling balls 108 touch the driven body 121.

[0035] Fig. Figure 6 is a perspective exploded view showing a major part of a design that holds the rolling balls 108 between the driven body 121 and the support body 122. Fig. 7A and Fig. 7B are views that describe an arrangement of the rolling balls 108 as seen from a -Y side.

[0036] Although in Fig. 1 to Fig. Figure 4 (not shown) shows a holder 109 positioned between the rolling receiving section 121b of the driven body 121 and the rolling receiving section 122b of the support body. The holder 109 is an annular component. An inner circumference 109b of the holder 109 is rotatably fitted to a holder fitting 122c formed in the support body 122. The holder 109 has ball retaining holes 109a for holding the rolling balls 108. The ball retaining holes 109a are arranged at approximately equal regular intervals (60-degree intervals) in a circumferential direction. Since the rolling balls 108 are housed in the ball retaining holes 109a, they are held at approximately equal intervals in the circumferential direction. That is, the holder 109 is a holding component that holds at least three rolling balls 108, so that they are movable in the circumferential direction around the axis of rotation P, accompanying the relative rotation of the driven body 121 and the support body 122.The holder 109 regulates the intervals between the at least three rolling balls 108, so that the at least three rolling balls 108 cannot touch each other.

[0037] Alternatively, the rolling balls 108 can be held not by the holder 109, but by an annular groove. For example, the annular groove is formed around the axis of rotation P in the support body 122. The rolling balls 108 are arranged in this annular groove. The rolling balls 108 can roll relative to the driven body 121 and the support body 122 in a state where the positions of the rolling balls 108 are regulated in the radial direction. It should be noted that the number of rolling balls 108 is not limited to six. At least three rolling balls 108 are necessary to maintain stable rotation. That is, the number of sliding elements, such as the rolling balls 108, is not limited to six. At least three sliding elements are necessary so that they surround the axis of rotation P.

[0038] A radius of the rolling path of the rolling balls 108 around the axis of rotation P is a circumferential radius Rr. In a projection view onto a plane perpendicular to the axis of rotation P, the circumferential radius Rr is a third distance from the axis of rotation P to a third position where a rolling ball 108 contacts the rolling receiving section 121b of the driven body 121. Since the inner circumference 109b of the holder 109 is rotatably fitted to the holder fitting 122c of the support body 122, the rolling balls 108 are held in a state where the circumferential radius Rr and the intervals are regulated.

[0039] It should be noted that the center of the holder fitting 122c is approximately aligned with the axis of rotation P. Furthermore, the diameter of the ball retaining holes 109a of the holder 109 is larger than the diameter of the rolling balls 108, and the thickness of the holder 109 itself is smaller than the diameter of the rolling balls 108. Accordingly, the rolling balls 108 are able to rotate and move freely while maintaining their relative intervals, thus ensuring secure retention.

[0040] As mentioned above, the shaft 121a of the driven body 121 is rotatably fitted into the rotary support hole 122a of the support body 122. As in Fig. 4, Fig. 7A and Fig. As shown in Figure 7B, in the projection view projected onto the plane perpendicular to the axis of rotation P, a first distance in the radial direction from the axis of rotation P to a first position where the shaft 121a is supported by the rotary support hole 122a is designated as a fit radius Rf. Furthermore, in the projection view projected onto the plane perpendicular to the axis of rotation P, a second distance from the axis of rotation P to a second position where the projection 102a of the vibrator 101 is in contact with the contact surface 121s of the driven body 121 is designated as a drive radius Rd. The second position is also a position where the drive force F2 ( Fig. 3) is generated.

[0041] The fit radius Rf is shorter than the drive radius Rd, and the circumferential radius Rr is longer than the drive radius Rd. This means the following relationship is satisfied: the fit radius Rf < the drive radius Rd < the circumferential radius Rr. A meshing relationship between the rotary support hole 122a and the shaft 121a forms a sliding friction element, and a meshing relationship between the rolling balls 108 and the rolling receiving section 121b forms a rolling friction element. The frictional force of the sliding friction element is greater than that of the rolling friction element. Therefore, the sliding friction element, which has the greater sliding friction, is located on the inside of the contact positions between the projections 102a and the contact points 102c in the radial direction. And the rolling friction element, which has the lesser sliding friction, is located on the outside of the contact positions in the radial direction.This prevents a loss of driving force due to sliding friction, which results from the losses of driving forces due to frictions between the components that are generated in conjunction with the rotary drive.

[0042] Furthermore, since the drive radius Rd is smaller than the rotation radius Rr, and since the contact positions between the rolling balls 108 and the rolling receiving section 121b lie outside the contact positions between the projections 102a and the contact points 102c, an enlargement of the vibration motor 100 is controlled. As in Fig. As shown in Figure 7A, for example, when a contour E of the vibrator 101 is projected onto the plane perpendicular to the axis of rotation P, the contact points 102c of the vibrator 101 lie within the circle of the radius of rotation Rr, and the contour E partially overlaps the circle of the radius of rotation Rr. That is, at least a part of the vibrator 101 is arranged side by side with a sliding track (rolling track) of the rolling balls 108 in the direction parallel to the axis of rotation P. This avoids the enlargement of the vibratory motor 100 in the radial direction. In particular, if the multitude of contact points 102c is provided to increase the driving force F2, as in the embodiment, the contour E of the vibrator 101 tends to enlarge. However, the above-mentioned design enables a layout with high spatial efficiency, and miniaturization of the vibratory motor 100 becomes simple.

[0043] Furthermore, since the drive radius Rd is smaller than the rotation radius Rr, a stable rotary drive is available. For comparison, a contact point 1020c and a rolling ball 1080 are described, which in Fig. Figure 4 shows a hypothetical case. In this hypothetical case, the vibration motor 100 is positioned such that the contact point 1020c of the vibrator 101 coincides with the position of the orbital radius Rr, and the rolling ball 1080 is located at the position of the drive radius Rd. In this hypothetical case, the rolling ball 1080 always rotates radially within the contact point 1020c of the vibrator 101. Accordingly, if a compressive force is applied to the contact point 1020c, an inclination θ about the rolling ball 1080 can occur, for example.

[0044] If a tilt prevention mechanism as described in JP 2006-158054 A is present in an area A ( Fig. 4) If the contact point 1020c is provided opposite to the axis of rotation P in order to compensate for the inclination θ, the motor size will be increased and the costs will rise. In the embodiment, the aforementioned inclination θ is prevented by providing the rolling balls 108 outside the contact points 102c, which enables a stable rotary drive.

[0045] It is necessary to fulfill a specific condition to prevent the occurrence of the inclination θ around the rolling ball 108, even when the rolling balls 108 are in any rotational phase due to their rotation. A preferable positional relationship between the rolling balls 108 and the vibrator 101 is described.

[0046] First, as in Fig. Figure 7A shows the case where the rolling spheres 108a to 108f are arranged at equal intervals (60-degree intervals) in the circumferential direction. A center point of the contact points 102c of the projections 102a with the contact surface 121s of the driven body 121 by the pressure-applying mechanism is defined as a pressure position f. The pressure position f lies approximately on the circle of the drive radius Rd. In the projection view projected onto the plane perpendicular to the axis of rotation P, a polygon S1, obtained by connecting the centers of the rolling spheres 108, and an inscribed circle C1 of the polygon S1 are defined. The contact points 102c of the vibrator 101 and the pressure position f lie within the inscribed circle C1 of the polygon S1.If the above positional relationship is satisfied, the contact points 102c and the pressure position f always lie in at least one of the triangles obtained by connecting the centers of the rolling spheres 108, even if the rolling spheres 108 are in any rotational phase.

[0047] For example, the state of Fig. 7A the points of contact 102c and the pressure position f in a triangle abc obtained by connecting the centers of the rolling spheres 108a, 108b and 108c. Fig. Figure 7B shows a rotational phase of the rolling balls 108, which is obtained by rotating the rolling balls 108 by 30 degrees around the axis of rotation P from the state that is in Fig. 7A is shown. Also in the one in Fig. In the state shown in 7B, the contact points 102c of the vibrator 101 and the pressure position f lie in the triangle abc, which is obtained by connecting the centers of the rolling balls 108a, 108b and 108c.

[0048] In this way, since the compressive force is supported by three points a, b, and c, the occurrence of the aforementioned inclination θ can be prevented. If the above positional relationship is satisfied, the same effect can be obtained even if the rolling balls 108 are in any rotational phase. In this case, the following applies: Fig. In the example shown in Figure 7B, the pressure position f lies not only in triangle abc but also in triangle bcd, which is obtained by connecting the centers of the rolling spheres 108b, 108c, and 108d. It should be noted that at least the pressure position f should lie within the inscribed circle C1 of the polygon S1, which is obtained by connecting the centers of the rolling spheres 108. Adjacent rolling spheres 108 do not necessarily have to form a triangle. In other words, it is sufficient that there are three rolling spheres 108 such that the pressure position f lies in the triangle obtained by connecting the centers of the three rolling spheres 108.Furthermore, the contact points 102c of the projections 102a, which touch the contact surface (a contact section) 121s, should be located in the Y-direction in any triangular area of ​​one or more triangular areas formed by connecting any three rolling spheres 108 from the at least three rolling spheres (supporting components) with straight lines.

[0049] Although the rolling balls 108 in the Fig. 6, Fig. 7A and Fig. In the example shown in Figure 7B, where the rolling balls 108 are arranged at equal intervals (60-degree intervals) in the circumferential direction around the axis of rotation P, they do not necessarily have to be arranged at equal intervals. A modified example, in which the rolling balls 108 are arranged at unequal intervals, is described with reference to Figure 7B. Fig. 8A and Fig. 8B described.

[0050] Fig. 8A and Fig. Figure 8B shows views describing the arrangement of the rolling balls 108 as seen from the -Y side. In the Fig. In the example shown in Figure 8, the rolling ball 108b is arranged at a position that is 10 degrees in the circumferential direction from the equi-interval position ( Fig. 7A). The contact points 102c and the pressure position f are arranged such that they lie within a circle C2 which touches a side bc which is closest to the axis of rotation P from the sides of a polygon obtained by connecting the centers of the rolling balls 108 and which has its center on the axis of rotation P.

[0051] If the above positional relationship is satisfied, the contact points 102c of the vibrator 101 and the pressure position f always lie in at least one of the triangles obtained by connecting the centers of the rolling balls 108, even if the rolling balls 108 are in any rotational phase. Also in the Fig. In the state shown in Figure 8A, the contact points 102c and the pressure position f lie in the triangle abc, which is obtained by connecting the centers of the rolling spheres 108a, 108b and 108c. In this way, since the pressure force is supported by three points a, b and c, the occurrence of the aforementioned inclination θ can be prevented.

[0052] Fig. Figure 8B shows a rotational phase of the rolling balls 108, which is achieved by rotating the rolling balls 108 by 25 degrees around the axis of rotation P of the one in Fig. The state shown in 8A is maintained. Also in the state shown in Fig. In the state shown in Figure 8B, the contact points 102c and the pressure position f lie in triangle abc, which is obtained by connecting the centers of the rolling spheres 108a, 108b, and 108c. In this way, since the pressure force is supported by triangle abc, the occurrence of the aforementioned inclination θ can be prevented. If the above positional relationship is satisfied, the same effect can be obtained even if the rolling spheres 108 are in any rotational phase. In this case, the... Fig. In the example shown in 8B, the pressure position f lies not only in triangle abc but also in triangle bcd, which is obtained by connecting the centers of the rolling spheres 108b, 108c and 108d.

[0053] It should be noted that at least the pressure position f should lie within the circle C2, which touches a side formed by the sides of the polygon obtained by connecting the centers of the rolling spheres 108 and which has a center on the axis of rotation P that is nearest to the axis of rotation P.

[0054] According to this embodiment, in the projection view onto the plane perpendicular to the axis of rotation P, the fit radius Rf is shorter than the drive radius Rd, and the circumferential radius Rr is longer than the drive radius Rd. This reduces the drive force due to sliding friction. Furthermore, since the high machining accuracy required to match the diameters of the V-grooves and eliminate decentering, unlike in the design of JP 2006-158054 A, is not necessary, the design is simplified and costs are avoided. Therefore, a vibration drive device can be provided that achieves low cost and high accuracy while reducing the drive load.

[0055] Furthermore, the pressure position f lies within the circle C2, which touches a side formed by the sides of the polygon obtained by connecting the centers of the rolling spheres 108 and which has a center on the axis of rotation P that is closest to the axis of rotation P. This condition is met in the Fig. 7A and Fig. The example shown in 7B and the one in Fig. 8A and Fig. The example shown in 8B is fulfilled. Alternatively, if the rolling spheres 108 are on the concentric circle around the axis of rotation P at approximately the same intervals ( Fig. 7A and Fig. 7B) are arranged, the pressure position f within the inscribed circle C1 of the polygon S1, which is obtained by connecting the centers of the rolling spheres 108. This condition is in the in Fig. 7A and Fig. The requirements of the example shown in 7B are met. These designs prevent the occurrence of the tilt θ and enable a stable rotary drive. Furthermore, they contribute to miniaturization, as a tilt prevention mechanism becomes unnecessary.

[0056] Next, the design of the driven body 121 will be described in detail by reference to Fig. 9A, Fig. 9B and Fig. 10 described. Fig. 9A and Fig. 9B are perspective exploded views showing the powered body 121. Fig. Figure 10 is a sectional view showing a main part of the vibration motor 100 and the driven body 121, which is shown in detail.

[0057] The powered body 121 is in Fig. 2, Fig. 3 and Fig. 4 shown schematically in simplified form. As in Fig. 9A and Fig. As shown in Figure 9B, the driven body 121, which forms the first unit, has the shaft (a basic component) 121a, the rolling receiving section (a second component) 121b, a friction component (a first component) 201, a spacer 202, a damping component 203, and connecting components 204. Fig. 9A, Fig. 9B and Fig. The 10 components that form the driven body 121 are shown individually.

[0058] Although he was not in Fig. As shown in Figure 10, the holder 109 holds the rolling balls 108 as shown in Figure 10. Fig. Figure 6 shows the intermediate position between the rolling receiving section 121b of the driven body 121 and the rolling receiving section 122b of the support body 122.

[0059] The friction component 201 is an annular component with a contact surface 121s. The spacer 202 and the rolling receiving section 121b are positioned between the friction component 201 and the shaft 121a in that order, from the side of the friction component 201. Furthermore, the damping component 203 is clamped between the friction component 201 and the rolling receiving section 121b, so that it surrounds the spacer 202. Six through holes, through which a plurality of connecting components (six fixing components) 204, such as screws, penetrate, are formed in each of the friction component 201, the spacer 202, and the rolling receiving section 121b. The holes in the friction component 201 are the fixed components 201a. The positions of the fixed parts 201a of the friction component 201 in the radial direction R are common to all. The six fixed parts 201a are arranged at approximately equal intervals. The number is arbitrary.Six screw holes, to which the six connecting components 204 are each attached, are formed in the shaft (base component) 121a.

[0060] The friction component 201 is fixed to the shaft 121a by the connecting components 204. The spacer 202 and the rolling receiving section 121b are also fixed to the shaft 121a together with the friction component 201 by the connecting components 204, which are the same fixing components (in a co-fixed configuration). In this configuration, the shaft 121a, as the base component, holds the friction component 201. Furthermore, the rolling receiving section 121b, as a pressure receiving component, receives the pressure force F1 from the vibrator 101, which results from the pressure-applying mechanism between the friction component 201 and the rolling receiving section 122b of the support body 122. The spacer 202 has a higher stiffness than the friction component 201.

[0061] As in Fig. As shown in Figure 10, the radial direction R begins at the axis of rotation P and intersects the axis of rotation P perpendicularly. Furthermore, in the projection view projected onto the plane perpendicular to the axis of rotation P (that is, in the radial direction R), a second distance from the axis of rotation P to a second position, where the projection 102a of the vibrator 101 is in pressure contact with the contact surface 121s of the driven body 121, is designated as the drive radius Rd. The second position is also a position where the drive force F2 ( Fig. 3) is generated. Furthermore, in the radial direction R, a distance from the axis of rotation P to a fourth position, at which the friction component 201 and the rolling receiving section 121b are together fixed to the shaft 121a, is designated as a fixing position radius Rx. The fixing position radius Rx is smaller than the drive radius Rd.

[0062] Since the rolling receiving section 121b is fixed together with the friction component 201 by the connecting components 204, an increase in the radial direction R is avoided compared to a design in which the rolling receiving section 121b and the friction component 201 are fixed individually. If only the prevention of the increase in the radial direction R is considered, a method can be considered that shifts the fixing positions of the friction component 201 relative to the fixing positions of the rolling receiving section 121b along the circumferential direction about the axis of rotation P. For example, each of the components can be fixed at three points at intervals of 120 degrees, and the fixing points of the components can be offset from each other by 60 degrees.

[0063] However, according to this method, the shape of the friction component 201 will have an asymmetrical odd shape around the axis of rotation P, which tends to have an unnecessary resonance. Since the fixing positions of the rolling receiving section 121b are the same as the fixing positions of the friction component 201 in this embodiment, the friction component 201 does not have an asymmetrical odd shape and has a shape that is unlikely to generate the unnecessary resonance. Furthermore, like the friction component 201, the rolling receiving section 121b does not have an asymmetrical odd shape. Since the rolling receiving section 121b does not have an asymmetrical odd shape, an unnecessary resonance is unlikely to be generated in the rolling receiving section 121b, caused by vibration transmitted from the friction component 201 through the spacer 202.

[0064] The circle of the fixing position radius Rx and the circle of the drive radius Rd are adjacent and close to each other. In the projection view projected onto the plane perpendicular to the axis of rotation P, the position at which the friction component 201 and the rolling receiving section 121b clamp the damping component 203 overlaps the circle of the drive radius Rd. In other words, the friction component 201 and the rolling receiving section 121b clamp the damping component 203 in the area that encompasses the circle of the drive radius Rd in the radial direction R.

[0065] In this embodiment, the friction component 201 and the rolling receiving section 121b are fixed together to the shaft 121a by the connecting components 204 at fourth positions on the circle of the fixing position radius Rx, which are within the second positions on the circle of the drive radius Rd. Initially, the vibration can be dampened by fixing the friction component 201 to the shaft 121a by the connecting components 204. As a result, unnecessary resonance of the friction component 201 is reduced and drive performance is improved.

[0066] Furthermore, since the positions of the fixed parts 201a are within the second positions where the vibrator 101 contacts the friction component 201, the friction component 201 can be held and fixed at positions close to the center of gravity of the driven body 121, and the moment of inertia of the entire driven body 121 can be suppressed, thus minimizing it. As a result, the drive performance is improved. Moreover, because the rolling receiving section 121b and the friction component 201 are fixed together on the shaft 121a, an increase in the radial direction R is avoided compared to a design where the rolling receiving section 121b and the friction component 201 are fixed individually. Additionally, the friction component 201 can be prevented from acquiring an irregular shape, and unnecessary resonance of the friction component 201 is reduced.Accordingly, the magnification can be controlled while ensuring good drive performance.

[0067] In particular, since the connecting components 204 fix the friction component 201 and the rolling receiving section 121b together at concentric positions around the axis of rotation P, space is saved in the radial direction R.

[0068] Furthermore, the friction component 201 and the rolling receiving section 121b clamp the damping component 203 in the area encompassing the circle of the drive radius Rd in the radial direction R. This further dampens the unnecessary resonance of the friction component 201 and prevents it from increasing in size.

[0069] Furthermore, since the circle of the fixing position radius Rx and the circle of the drive radius Rd are adjacent and close to each other in the radial direction R, the length of a beam can be shortened if the friction component 201 is considered as the beam extending in the radial direction R. As a result, this contributes to controlling the unnecessary resonance of the friction component 201. Moreover, from this perspective, if the difference between the fixing position radius Rx and the drive radius Rd is sufficiently shorter than the fixing position radius Rx, the effect of resonance control is achieved.

[0070] Furthermore, the spacer 202, whose stiffness is higher than that of the friction component 201, is positioned between the friction component 201 and the rolling receiving section 121b. This allows the vibration damping effect obtained by fixing the friction component 201 to be increased.

[0071] Next, a second embodiment will be described. Fig. Figure 11 is a perspective exploded view showing a main part of a mechanism for holding the rolling balls 108 between the driven body 121 and the support body 122 in the second embodiment of the invention. Fig. Figure 12 is a view that describes an arrangement of the rolling balls 108 as seen from a -Y side.

[0072] In this embodiment, the number of rolling balls 108 and the holding mechanism of the rolling balls 108 differ from those of the first embodiment, and the further designs are identical. Fig. 11 and Fig. 12 each correspond to Fig. 6 and Fig. 7A.

[0073] The vibration motor 100 of this embodiment does not have the holder 109. The rolling balls 108 are held only by the support body 122 and the driven body 121. In particular, an annular groove G is formed in the support body 122. The annular groove G is formed by the rolling receiving section 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 coincides approximately with the axis of rotation P. A distance from the axis of rotation P to a center position of the annular groove G in the radial direction R is equal to the radius of rotation Rr. Accordingly, the rolling balls 108 can roll relative to the driven body 121 and the support body 122 in a state in which the positions of the rolling balls 108 are regulated in the radial direction.

[0074] Since the rolling balls 108 are arranged in the annular groove G such that they have sufficient clearance in the circumferential and radial directions, the rolling balls 108 can rotate and orbit while maintaining approximately constant intervals between them, thus ensuring good rotational stability. The relationship between the drive radius Rd, the fit radius Rf, and the orbital radius Rr is the same as in the first embodiment. Furthermore, the relationship between the contour E of the vibrator 101 and the orbital radius Rr is the same as in a first embodiment ( Fig.12) It should be noted 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 differs from the design of the aforementioned JP 2006-158054 A, where the V-grooves are formed on both sides. Accordingly, since high machining accuracy is not required, the design is simple and an increase in costs is avoided. If a groove is not a V-groove, the annular grooves G can be formed in both the driven body 121 and the support body 122.

[0075] According to this embodiment, the same effect as that of the first embodiment is obtained with regard to a requirement of low cost and a high-precision vibration drive device, while reducing the drive load.

[0076] Although the example in which the image acquisition device 21 is rotary-driven by the vibration motor 100 is described in each of the aforementioned embodiments, the invention is applicable to a device that has a movable body which is rotary-driven by the vibration motor 100. For example, in this case, a laser irradiation device, an arm unit of a robot arm, etc., correspond to the movable body.

[0077] In each of the embodiments, a word to which a modification such as "approximately" or "closely related" is added does not preclude an exact match. For example, "approximately equal intervals," "approximately congruent," "approximately constant," "approximately center," "approximately ring shape," and "approximately equal" each encompass "equal intervals," "congruent," "constant," "center," "ring shape," and "equal." Other embodiments

[0078] While the invention has been described with reference to exemplary embodiments, it is understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be interpreted in the broadest possible way, so that it includes all such modifications and equivalent structures and functions.

[0079] This application claims the advantage of Japanese patent applications No. 2020-145845 and No. 2020-145846 filed on August 31, 2020, which are hereby incorporated herein by reference in their entirety.

[0080] A vibratory drive device that achieves low cost and high accuracy while reducing the drive load. A drive unit has a vibrator with a projection and generates a driving force by vibrating the vibrator. A first unit has a contact section with which the projection is in pressure contact in a first direction. A second unit rotates relative to the first unit about an axis of rotation parallel to the first direction due to the driving force. At least three support components are provided to rotatably support the first and second units in the first direction.The support components are positioned such that, during a relative rotation of the first and second units, a point of contact where the projection touches the contact section is always located in at least one of triangular areas in the first direction, which are formed by connecting any three support components with straight lines. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2018189745 A [0002, 0003] JP 2006158054

[0002] JP 2006158054 A [0002, 0003, 0005, 0006, 0044, 0054, 0074] JP 2004304887

[0002] JP 2004304887 A [0002, 0033] JP 2018

[0004] JP 189745 A

[0004] JP 2004

[0006] JP 304887 A

[0006] JP 2020145845

[0079] JP 2020145846

[0079]

Claims

[1] Vibration drive device comprising: a drive unit which has a vibrator provided with a projection and is designed to generate a driving force by vibrating the vibrator; a first unit which has a contact section with which the projection is in pressure contact in a first direction; a second unit designed to rotate, by means of the driving force of the drive unit, relative to the first unit about a predetermined axis of rotation parallel to the first direction; and at least three supporting components between the first unit and the second unit in the first direction, designed to support the first unit and the second unit in such a way that they are relatively rotatable, wherein the support components are positioned such that, during a relative rotation of the first unit and the second unit, a point of contact where the projection touches the contact section is always located in at least one triangular area of ​​one or more triangular areas, as seen in the first direction, which is formed by connecting any three support components from the at least three support components with straight lines. [2] Vibration drive device according to claim 1, wherein, during a relative rotation of the first unit and the second unit, the point of contact seen in the first direction never coincides with any of the at least three support components. [3] Vibration drive device according to claim 1, which further comprises a holding component which holds the at least three support components, so that they are movable in a circumferential direction of the predetermined axis of rotation accompanying the relative rotation of the first unit and the second unit. [4] Vibration drive device according to claim 3, wherein the holding component is designed to regulate intervals between the at least three support components so that the at least three support components cannot touch each other. [5] Vibration drive device according to claim 1, wherein the first unit has a first component having the contact section, a second component having the at least three support components, and a damping component between the first component and the second component. [6] Vibration drive device according to claim 5, wherein the first unit has fixing components that fix the first component, the second component and the damping component to a base component. [7] Vibration drive device according to claim 6, wherein in a plane which intersects the first direction perpendicularly, the distance between the predetermined axis of rotation and the fixing components is shorter than the distance between the predetermined axis of rotation and the projection. [8] Image recording device which features: a drive unit which has a vibrator provided with a projection and is designed to generate a driving force by vibrating the vibrator; a first unit which has a contact section with which the projection is in pressure contact in a first direction; a second unit designed to rotate relative to the first unit about a predetermined axis of rotation parallel to the first direction by means of the driving force of the driving unit; at least three supporting components between the first unit and the second unit in the first direction, designed to support the first unit and the second unit so that they are relatively rotatable; and an image acquisition unit whose image acquisition direction changes according to the relative rotation of the first unit and the second unit, wherein the support components are positioned such that, during a relative rotation of the first unit and the second unit, a point of contact where the projection touches the contact section is always located in at least one triangular area of ​​one or more triangular areas, as seen in the first direction, which is formed by connecting any three support components from the at least three support components with straight lines. [9] Image recording device according to claim 8, wherein, during a relative rotation of the first unit and the second unit, the point of contact seen in the first direction never coincides with any of the at least three support components. [10] Image acquisition device according to claim 8, which further comprises a holding component which holds the at least three support components, such that they are movable in a circumferential direction of the predetermined axis of rotation accompanying the relative rotation of the first unit and the second unit. [11] Image acquisition device according to claim 10, wherein the holding component is designed to regulate intervals between the at least three support components so that the at least three support components cannot touch each other. [12] Image acquisition device according to claim 8, wherein the first unit has a first component having the contact section, a second component having the at least three support components, and a damping component between the first component and the second component. [13] Image acquisition device according to claim 12, wherein the first unit has fixing components that fix the first component, the second component and the damping component to a base component. [14] Image recording device according to claim 13, wherein in a plane which intersects the first direction perpendicularly, the distance between the predetermined axis of rotation and the fixing components is shorter than the distance between the predetermined axis of rotation and the projection.