JP7183225B2 - Vibration type driving device and imaging device - Google Patents

Description

The present invention relates to a vibration-type driving device and an imaging device that generate rotational driving force by vibration and frictional force.

2. Description of the Related Art Conventionally, an electronic device such as an imaging device employs a vibration-type driving device that generates rotational driving by excited vibration and frictional force. 2. Description of the Related Art As a vibration type driving device, a rotary vibration type motor is known which has the characteristics of small size, high output, and quietness.

In such a rotary vibration type motor, an annular vibrator, which is a driving source, uniformly presses and biases an annular friction member (contacted member) over the entire annular surface. There is also a configuration in which the driving force in the rotational direction is obtained by utilizing the frictional force generated by the pressurization. On the other hand, as disclosed in Patent Documents 1 and 2, a vibrator having a relatively small size with respect to an annular friction member is configured to pressurize and energize only a specific position on the circumference of the friction member. A vibrating motor has also been proposed. Such a vibration type motor is advantageous for miniaturization due to the small size of the vibrator.

JP 2006-158054 A Japanese Patent Application Laid-Open No. 2004-304887

However, if the regulation is limited to a specific position on the circumference, the friction member is likely to generate unnecessary resonance due to the lack of regulation. Driving characteristics may deteriorate. On the other hand, in order to suppress unnecessary resonance of the friction member, a method of damping vibration by fixing the friction member to a fixed member with a screw or the like is conceivable. However, if the friction member is fixed to the fixing member without any ingenuity, there is a possibility that unnecessary resonance will occur or the size of the entire unit will be increased.

SUMMARY OF THE INVENTION It is an object of the present invention to ensure good driving characteristics and to suppress an increase in size.

In order to achieve the above object, the present invention provides a substantially annular contact member, a holding member that holds the contact member, and a contact member that presses and contacts the contact member and vibrates the contact member. a drive unit that rotationally drives a contact member; a pressurizing unit that presses the drive unit against the contact member; a pressure receiving member that receives pressure from the drive unit ; a spacer member interposed between a pressure receiving member and a second position radially of the contacted member, which is inner than a first position at which the driving portion is in pressure contact with the contacted member, fixing means for collectively fixing the contacted member , the pressure receiving member and the spacer member to the holding member; and a damping member that is not fixed to the fixing means but is sandwiched between the contacted member and the pressure receiving member .

ADVANTAGE OF THE INVENTION According to this invention, a favorable drive characteristic can be ensured and an increase in size can be suppressed.

1 is a schematic diagram of an electronic device; FIG. 1 is an exploded perspective view of a vibration type motor; FIG. 1 is an exploded perspective view of a vibration type motor; FIG. FIG. 3 is a cross-sectional view of a main part of the vibration type motor; FIG. 4A is a schematic diagram of a vibration mode of a vibrator, and a schematic diagram of a protrusion that makes an elliptical motion. 3 is an exploded perspective view of a driven body; FIG. FIG. 3 is a cross-sectional view of the main part of the vibration type motor showing the driven body in detail;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an electronic device to which a vibration-type driving device according to an embodiment of the invention is applied. A turning drive device 1 is exemplified as this electronic device. The turning drive device 1 includes a fixed body 10 and a movable body 20 rotatable with respect to the fixed body 10 . The fixed body 10 includes a vibration motor 100 as a vibration drive device and a control board (not shown) that controls the entire swing drive device 1 . Vibrational motor 100 is shown in cross-section. The movable body 20 includes an imaging device 21 that is an imaging unit capable of imaging a subject. Note that the entire turning drive device 1 may be called an imaging device.

The vibration-type motor 100 is a rotary ultrasonic motor provided with a vibrator 101 (described later) that rotationally drives a driven body 121 using vibration. The movable body 20 is connected to the driven body 121 of the vibration motor 100 . The movable body 20 including the imaging device 21 rotates about the rotation center P by rotating the driven body 121 by the vibrator 101 .

The turning drive device 1 is configured such that the movable body 20 is connected to the driven body 121 and the supporting body 122 is fixed. However, conversely, the swing drive device 1 may be configured such that the movable body 20 is connected to the support body 122 and the driven body 121 is fixed.

2 and 3 are exploded perspective views of the vibration type motor 100. FIG. FIG. 4 is a cross-sectional view of the essential parts of the vibration type motor 100. As shown in FIG.

Hereinafter, directions of respective parts will be referred to with reference to the X, Y, and Z coordinate axes shown in FIGS. Here, for convenience, the direction parallel to the axial direction of the rotation center P is defined as the Y direction. In particular, in the Y direction, the side where the driven body 121 is positioned with respect to the vibrator 101 is the +Y direction. A longitudinal direction of the vibrator 101 is defined as a Z direction. A direction orthogonal to the Y direction and the Z direction is defined as the X direction.

Vibration-type motor 100 mainly includes support body 122, driven body 121, and chassis 122d. The support 122 holds the entire vibrating motor 100 . The driven body 121 is a substantially annular member as a whole. The driven body 121 has a shaft portion 121a, a rolling receiving portion 121b, and a contact surface 121s. 121 s of contact surfaces are friction surfaces. The support 122 is formed with a rotation support hole 122a. A shaft portion 121a of the driven body 121 is rotatably fitted (supported) in the rotation support hole 122a. As a result, the entire driven body 121 is rotatable about the rotation center P relative to the support body 122 . Therefore, the vibration type motor 100 has a slide bearing structure in the radial direction.

Since the vibration type motor 100 has a simple configuration in which the fitting relationship in the radial direction is determined by the rotation support hole 122a and the shaft portion 121a, fitting accuracy can be easily ensured at a relatively low cost. In addition, the driven body 121 may be composed of a single member, or the disc-shaped portion including the contact surface 121s and the rolling receiving portion 121b and the shaft portion 121a may be composed of separate members. Alternatively, the relationship between the shaft portion 121a and the rotation support hole 122a may be reversed. That is, by providing a rotation support hole in the driven member 121 and providing a shaft portion in the supporting member 122 and fitting them together, the entire driven member 121 can be rotated relative to the supporting member 122. It may be configured as

A vibrator 101 as a drive unit has an elastic body 102 and a piezoelectric element 103 . The piezoelectric element 103 is an electro-mechanical energy conversion element that excites the elastic body 102 to vibrate. The piezoelectric element 103 is made of PZT (lead zirconate titanate), for example. The elastic body 102 is made of sheet metal such as stainless steel.

The elastic body 102 has two protruding portions 102a and two held portions 102b arranged in the longitudinal direction (FIG. 2). The elastic body 102 and the piezoelectric element 103 are fixed with an adhesive or the like. With both of them fixed, the piezoelectric element 103 is pressed by a pressure mechanism, which will be described later, so that the projection 102a comes into pressure contact with the contact surface 121s of the driven body 121 . By applying a high-frequency AC drive voltage to the piezoelectric element 103, the vibration of the frequency in the ultrasonic range (ultrasonic vibration) causes the protrusion 102a of the elastic body 102 to move in an elliptical motion EM (Fig. 5(a), ( b)) occurs. As a result, a driving force is generated between the protrusion 102a and the contact surface 121s. A contact position between the projection 102a and the contact surface 121s is a position where a driving force F2 (FIG. 3), which will be described later, is generated.

The support member 122 is formed with a rolling receiving portion 122b that faces the rolling receiving portion 121b of the driven member 121 . A plurality of (six in the drawing) rolling balls 108 are provided between the rolling receiving portion 122b and the rolling receiving portion 121b. That is, the support structure for the thrust direction of the vibration type motor 100 is a rolling bearing structure, and the driven body 121 and the support body 122 can rotate relatively smoothly through the rolling of the rolling balls 108. . As a result, the frictional resistance when the driven body 121 moves while receiving pressure can be minimized.

Note that the rolling receiving portion 122b may be provided integrally with the support 122, but may be configured as a separate member. Further, the rolling receiving portion 121b may be provided integrally with the driven body 121, or may be configured as a separate member. Instead of the rolling ball 108, a rolling member such as a roller or a roller may be provided between the rolling receiving portion 122b and the rolling receiving portion 121b, or a sliding member may be provided.

The first holding member 104 holds the elastic body 102 fixedly by holding the held portion 102 b of the elastic body 102 . Thereby, the vibrator 101 and the first holding member 104 move integrally. Chassis 122 d is fixed to support 122 . The frame member 113 holds the first holding member 104 via the elastic connecting member 114 . By fixing the frame member 113 to the chassis 122 d with a plurality of screws 115 , the first holding member 104 is positioned and fixed to the driven body 121 .

The blocking member 105 has a function of blocking the transmission of vibration to other components. The blocking member 105 suppresses the ultrasonic vibration of the piezoelectric element 103 from propagating to the small base 106 described later, but does not attenuate the ultrasonic vibration of the piezoelectric element 103 . Felt fabric is suitable as a material for the blocking member 105 . The small base 106 is in surface contact with the piezoelectric element 103 through the blocking member 105 and has a function of transmitting the pressure force of the pressure spring 111 to the piezoelectric element 103 .

The pressure mechanism includes a pressure member 110 , a pressure spring 111 as pressure means, and a receiving member 112 . The second holding member 107 holds this pressure mechanism. The second holding member 107 is fixed to the chassis 122 d with two screws 115 together with the frame member 113 . A circular fitting hole portion 112 a is formed in the center of the receiving member 112 , and a screw portion 112 b is formed on the outer peripheral surface of the receiving member 112 . The receiving member 112 is fixed to the second holding member 107 by screwing the screw portion 112 b into the screw hole 107 a of the second holding member 107 . Further, the fitting hole portion 112a fits and holds the fitting shaft portion 110a of the pressure member 110 . The pressurizing member 110 is fitted into the fitting hole 112a of the receiving member 112 and held so as to be movable only in a direction substantially perpendicular to the contact surface 121s of the driven body 121 .

The pressing member 110 transmits the pressing force from the pressing spring 111 to the vibrator 101 via the small base 106 and the blocking member 105 . As a result, the vibrator 101 is brought into pressure contact with the driven body 121 . The pressure spring 111 is composed of, for example, a compression coil spring. One end of the pressure spring 111 is fixed to the receiving member 112 and the other end is in contact with the pressure member 110 . In this manner, the pressure spring 111 generates a pressure force F1 by fixing both ends thereof in a compressed state. The generated pressing force F1 is transmitted to the piezoelectric element 103 and acts in the direction perpendicular to the contact surface 121s of the driven body 121 (+Y direction). The pressure F1 brings the vibrator 101 and the driven body 121 into contact with each other. Therefore, the +Y direction is the pressing direction of the pressing spring 111 . The rolling ball 108 is an example of a sliding member that receives the pressure F1 between the driven body 121 and the support body 122 . The pressurizing position where the pressurizing force F1 is applied is set substantially at the center between the two projections 102a of the elastic body 102 in the longitudinal direction of the vibrator 101. As shown in FIG. As a result, the two protrusions 102a can be pressed into contact with the driven body 121 in a well-balanced manner.

In this way, each member is assembled into a unit, and the vibration type motor 100 is configured. In this configuration, when the vibrator 101 vibrates and an elliptical motion EM (FIG. 5(c)) is generated in the projection 102a, the driving force F2 (Fig. 3) occurs. Since the driving force F2 is perpendicular to the radial direction centered on the rotation center P of the driven body 121, the driven body 121 is rotationally driven around the rotation center P. FIG.

Next, vibration modes of the vibrator 101 of the vibration type motor 100 will be described with reference to FIGS. 5(a) to 5(c). 5A and 5B are schematic diagrams showing vibration modes of the vibrator 101. FIG. FIG. 5(c) is a schematic diagram of the protrusion 102a that performs the elliptical motion EM.

A vibration mode of the vibrator 101 is a composite vibration including a first vibration and a second vibration. In the first vibration, as shown in FIG. 5A, the protruding portion 102a of the vibrator 101 generates a reciprocating motion M1 indicated by an arrow, and displaces the protruding portion 102a mainly in the tangential direction of the contact surface 121s. Vibration. A plurality of nodes N1 are generated in the first vibration. The vibrator 101 has three nodes N1 indicated by dashed lines, and the nodes N1 on both ends in the longitudinal direction of the vibrator 101 are located near the protrusions 102a.

As shown in FIG. 5B, the second vibration is a vibration that causes the projection 102a to generate a reciprocating motion M2 indicated by an arrow, and displaces the projection 102a mainly in the direction of contacting and separating from the contact surface 121s. be. A plurality of nodes N2 are generated in the second vibration. Vibrator 101 has two nodes N2 indicated by dashed lines.

By generating the first vibration and the second vibration at the same frequency, an elliptical motion EM is generated at the contact point 102c (FIGS. 4 and 5C) with the contact surface 121s of the protrusion 102a. can be done. In the vibrator 101, a plurality (two) of contact points 102c are provided in order to generate a larger driving force F2, but providing a plurality of contact points is not essential. Details of the method for generating the first vibration and the second vibration are well known, as described in Japanese Patent Application Laid-Open No. 2004-304887, for example, so detailed description thereof will be omitted here.

Next, a detailed configuration of the driven body 121 will be described with reference to FIGS. 6 and 7. FIG. 6A and 6B are exploded perspective views of the driven body 121. FIG. FIG. 7 is a cross-sectional view of a main part of vibration type motor 100 showing driven body 121 in detail.

In FIGS. 2 to 4, the driven body 121 is shown schematically in a simplified manner. As shown in FIG. 7, the driven body 121 has a shaft portion 121a, a rolling receiving portion 121b, a friction member 201 (contacted member), a spacer member 202, a damping member 203 and a connecting member 204. 6 and 7 individually show elements constituting the driven body 121. FIG.

Although not shown, a retainer is interposed between the rolling receiving portion 121b of the driven body 121 and the rolling receiving portion 122b of the support 122. As shown in FIG. The retainer is a ring-shaped member. The retainer is rotatably fitted to support 122 . The retainer has a plurality of ball retaining holes for retaining rolling balls 108 . The plurality of ball holding holes are arranged at substantially equal intervals (for example, at intervals of 60°) in the circumferential direction. By housing the rolling balls 108 in the ball holding holes, the rolling balls 108 are held at substantially equal intervals in the circumferential direction.

Alternatively, multiple rolling balls 108 may be retained by an annular groove rather than a retainer. For example, the support 122 is formed with an annular groove around the rotation center P. As shown in FIG. A plurality of rolling balls 108 are arranged in this annular groove. The plurality of rolling balls 108 can roll with respect to the driven body 121 and the support body 122 while the revolution radius (rolling trajectory), that is, the position in the radial direction is restricted. Although the number of rolling balls 108 is not limited to six, at least three or more rolling balls 108 are required for stable rolling and holding. That is, for stable driving, the number of sliding members such as the rolling balls 108 is not limited to six, and at least three may be provided so as to surround the rotation center P.

The friction member 201 is an annular member having a contact surface 121s. A spacer member 202 and a rolling receiving portion 121b are interposed in order from the friction member 201 side between the friction member 201 and the shaft portion 121a. Further, a damping member 203 is sandwiched outside the spacer member 202 between the friction member 201 and the rolling receiving portion 121b. The friction member 201, the spacer member 202, and the rolling receiving portion 121b are formed with six holes through which connecting members 204 such as a plurality of (six) screws pass. A hole in the friction member 201 is a fixing portion 201a. The positions of the plurality of fixing portions 201a of the friction member 201 in the radial direction R are common to each other. Six of the plurality of fixing portions 201a are arranged at approximately equal intervals, but the number does not matter. A screw hole into which the connecting member 204 is screwed is formed in the shaft portion 121a.

The friction member 201 is fixed to the shaft portion 121 a by a plurality of connecting members 204 . The spacer member 202 and the rolling receiving portion 121b are also collectively fixed (in a jointly tightened state) to the shaft portion 121a together with the friction member 201 by the connecting member 204, which is the same fixing means. With such a configuration, the shaft portion 121 a as a holding member holds the friction member 201 . Further, the rolling receiving portion 121b as a pressure receiving member receives the pressure F1 from the vibrator 101 caused by the pressure mechanism between the friction member 201 and the rolling receiving portion 122b of the support 122. FIG. Spacer member 202 is stiffer than friction member 201 .

As shown in FIG. 7, the radial direction R is a direction perpendicular to the rotation center P starting from the rotation center P. As shown in FIG. In a projection view from a direction parallel to the rotation center P (that is, in the radial direction R), the position (first position) is called a drive radius Rd. The first position is also the position where the driving force F2 (FIG. 1(b)) is generated. In the radial direction R, the distance from the rotation center P to the position (second position) where the friction member 201 and the rolling receiving portion 121b are collectively fixed to the shaft portion 121a is defined as the fixed position radius. Called Rx. In the radial direction R, the position of the fixed position radius Rx (second position) is inside the position of the drive radius Rd (first position).

Since the rolling receiving portion 121b is collectively fixed together with the friction member 201 by the connecting member 204, compared to a configuration in which the rolling receiving portion 121b and the friction member 201 are individually fixed, an increase in size in the radial direction R is avoided. be able to. Here, if it is only possible to avoid an increase in size in the radial direction R, a method of avoiding the fixed positions of the friction member 201 and the rolling receiving portion 121b along the circumferential direction around the rotation center P is conceivable. . For example, it is conceivable that each part is fixed at three points every 120 degrees and the fixed positions are shifted from each other by 60 degrees.

However, with this method, the shape of the friction member 201 becomes asymmetrical with respect to the center of rotation P, and tends to have an unnecessary resonance mode. As in the present embodiment, by sharing the fixing portion with the rolling receiving portion 121b of the friction member 201, it is possible to avoid the friction member 201 from being deformed, and to make the shape less likely to cause unnecessary resonance. can be done. Further, like the friction member 201, the rolling receiving portion 121b can also be prevented from being deformed. Unnecessary resonance generated in the rolling contact receiving portion 121b due to vibration propagated from the friction member 201 via the spacer member 202 can also be made less likely to occur by avoiding the deformation of the rolling contact receiving portion 121b. .

The position of the fixed position radius Rx and the position of the driving radius Rd are adjacent and close to each other. In a projection view from a direction parallel to the center of rotation P, the position where the damping member 203 is sandwiched between the friction member 201 and the rolling receiving portion 121b overlaps the position of the driving radius Rd. In other words, the friction member 201 and the rolling receiving portion 121b sandwich the damping member 203 in a region including the position of the driving radius Rd in the radial direction R.

According to the present embodiment, in the radial direction R, the friction member 201 and the rolling receiving portion are located at the position of the fixed position radius Rx (second position) inside the position of the driving radius Rd (first position). 121b are collectively fixed to the shaft portion 121a by a connecting member 204. As shown in FIG. First, by fixing the friction member 201 to the shaft portion 121a with the connecting member 204, vibration can be damped. As a result, unnecessary resonance of the friction member 201 is reduced, and driving characteristics are improved. Further, since the position of the fixing portion 201a is inside the first position where the vibrator 101 and the friction member 201 are in frictional contact, the friction member 201 can be held and fixed at a position close to the center of gravity of the driven body 121. As a result, the moment of inertia of the entire driven body 121 can be kept small. As a result, driving characteristics are improved. Furthermore, since the rolling receiving portion 121b is collectively fixed to the shaft portion 121a together with the friction member 201, compared to a mode in which the rolling receiving portion 121b and the friction member 201 are individually fixed, the size in the radial direction R is increased. can be avoided. In addition, it is possible to prevent the friction member 201 from becoming irregular in shape, thereby reducing unnecessary resonance of the friction member 201 . Therefore, it is possible to ensure good driving characteristics and to suppress an increase in size.

In particular, since the connecting member 204 collectively fixes the friction member 201 and the rolling receiving portion 121b at a plurality of concentric locations around the rotation center P, the space in the radial direction R can be saved.

In addition, the friction member 201 and the rolling receiving portion 121b sandwich the damping member 203 in a region including the position of the driving radius Rd in the radial direction R. As a result, unnecessary resonance of the friction member 201 can be further damped, and it does not lead to an increase in size.

In addition, since the position of the fixed position radius Rx and the position of the drive radius Rd are adjacent and close in the radial direction R, the beam length when the friction member 201 is viewed as a beam extending in the radial direction R is shortened. be able to. As a result, it contributes to suppression of unnecessary resonance of the friction member 201 . From this point of view, if the distance between the position of the fixed position radius Rx and the position of the drive radius Rd is sufficiently shorter than the fixed position radius Rx, the effect of suppressing resonance can be obtained.

A spacer member 202 having a higher rigidity than the friction member 201 is interposed between the friction member 201 and the rolling receiving portion 121b. As a result, the effect of damping vibration by fixing the friction member 201 can be enhanced.

Although an example in which the imaging device 21 is rotationally driven by the vibration motor 100 has been described, the present invention is applicable to any device having a rotating body that is rotationally driven by the vibration motor 100 . Examples of the rotating body in this case include an irradiation device such as a laser beam and an arm portion of a robot arm.

It should be noted that, in each embodiment, the abbreviation does not mean that completeness is excluded. For example, "substantially equidistant", "substantially coincident", "substantially centered", and "substantially toroidal" are meant to include equidistant, coincident, centered, and toroidal, respectively.

Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various forms without departing from the gist of the present invention can be applied to the present invention. included.

101 Oscillator 121 Driven Body 121a Shaft 121b Rolling Receiving Part 122 Support 201 Friction Member 204 Connection Member P Rotation Center

Claims (7)

a substantially annular contacted member;
a holding member that holds the contacted member;
a driving unit that pressurizes and contacts the contacted member and rotationally drives the contacted member using vibration;
a pressurizing means for pressurizing the driving portion against the contacted member;
a pressure receiving member that receives pressure from the drive unit;
a spacer member interposed between the contacted member and the pressure receiving member;
In the radial direction of the contacted member, the contacted member, the pressure receiving member , and the spacer member are positioned at a second position inside a first position where the driving portion is in pressure contact with the contacted member. a fixing means for collectively fixing to the holding member;
a damping member arranged in a region including the first position along with the spacer member in the radial direction, and not fixed to the fixing means but sandwiched between the contacted member and the pressure receiving member. A vibration type driving device characterized by: 2. The vibration type driving device according to claim 1 , wherein said second position is close to said first position in said radial direction. The fixing means collectively fixes the contacted member , the pressure receiving member , and the spacer member to the holding member at a plurality of concentric points centered on a rotational center of the rotational driving of the contacted member. 3. The vibration type driving device according to claim 1 or 2 , characterized in that: 4. The vibration type driving device according to claim 1 , wherein the spacer member has higher rigidity than the contacted member. further comprising a support that supports the holding member so as to be rotatable around the center of rotation;
5. The vibration type driving device according to claim 1 , wherein the pressure receiving member receives pressure from the driving portion between the contacted member and the support. . The drive unit has an elastic body that contacts the contacted member and an element that excites vibration of the elastic body,
6. The vibration type driving device according to claim 1, wherein the contact member is rotationally driven by vibrations excited by the elastic body. a vibration type driving device according to any one of claims 1 to 6 ;
and an imaging unit driven by the vibration type driving device.

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