JP5326325B2 - Vibration actuator, lens barrel, optical equipment - Google Patents

Description

  The present invention relates to a vibration actuator, a lens barrel, and an optical device.

2. Description of the Related Art Conventionally, a vibration actuator including a stator that vibrates according to a drive signal and a rotor that is driven according to the vibration of the stator is known (for example, see Patent Document 1).
Japanese Patent Application Laid-Open No. 11-69850

In this type of vibration actuator, the rotor and the stator are brought into pressure contact with each other, and they may adhere to each other and the rotor may not be driven.
An object of the present invention is to provide a vibration actuator, a lens barrel, and an optical device that can prevent the rotor and the stator from sticking to each other.

The invention of claim 1 includes a stay data which is formed in an annular shape, has a contact surface of the annular contact with the stator, and a low motor which rotates in response to the vibration of the stator, and the said stator rotor the and a pressure part for pressing in the direction intersecting the contact surface, the rotor comprises a body portion formed in an annular shape, and a contact portion having a contact surface, said contact surface and substantially from the body portion A connecting portion that extends in a parallel direction and connects the main body portion and the contact portion; and a height of the contact portion is 2.2 times or more a thickness of the connection portion. Thus, in the pressurization state by the pressurizing unit, the angle formed between the surface orthogonal to the rotation axis around which the rotor rotates and the direction in which the connection portion extends is the surface orthogonal to the rotation axis and the contact unit vibrations a, wherein the contact surface is the angle of 4 times or more Chue is another.

The invention of claim 2 is the vibration actuator according to claim 1, wherein the stay data is vibration actuator, wherein a polymer film is formed on the contact surface between the low data.
The invention according to claim 3, the vibration actuator according to claim 2, wherein the polymer film, epoxy resin, phenol resin, polyimide resin, a vibration actuator, characterized in that it comprises at least one PEEK resin.
The invention of claim 4 is a lens barrel comprising a vibration actuator according to any one of up to claims 1 to 3, and a lens that is linked to an output shaft provided in the vibration actuator .
The invention of claim 5, Ru Oh in optical equipment, characterized in that it comprises a vibration actuator according to any one of claims 1 to 3.

  According to the present invention, it is possible to provide a vibration actuator, a lens barrel, and an optical device that can suppress the fixation between the rotor and the stator.

Hereinafter, embodiments of the vibration actuator will be described in detail with reference to the accompanying drawings. In the present embodiment, an ultrasonic motor using an ultrasonic vibration region will be described as an example of the vibration actuator.
FIG. 1 is a diagram illustrating a camera system according to an embodiment.
The camera system 1 according to the embodiment includes a camera body 2 having an image sensor 8 and a lens barrel 3 having a lens 7. The lens barrel 3 is an interchangeable lens that can be attached to and detached from the camera body 2. In the present embodiment, the lens barrel 3 is an interchangeable lens. However, the present invention is not limited to this. For example, the lens barrel 3 may be a lens barrel integrated with the camera body.

  The lens barrel 3 includes a lens 7, a cam barrel 6, a gear 5, an ultrasonic motor 10, and the like. In this embodiment, the ultrasonic motor 10 is used as a drive source that drives the lens 7 during the focusing operation of the camera system 1, and the output of the ultrasonic motor 10 is a cam that holds the lens 7 via the gear 5. It is transmitted to the cylinder 6. The lens 7 is a focus lens that moves in the optical axis direction by the output of the ultrasonic motor 10 and performs focus adjustment.

FIG. 2 is a cross-sectional view of the ultrasonic motor according to the embodiment.
The ultrasonic motor 10 according to the present embodiment includes a stator 11, a rotor 15, an output shaft 18, a pressure member 19, and the like. The stator 11 side is fixed and the rotor 15 is rotationally driven.
The stator 11 is a substantially annular member having an elastic body 12 and a piezoelectric body 13 joined to the elastic body 12.
The elastic body 12 is formed of a metal material having a high resonance sharpness, and has a substantially annular shape. The elastic body 12 includes a comb tooth portion 12a, a base portion 12b, and a flange portion 12c.
The comb tooth portion 12a is formed by cutting a plurality of grooves on the surface opposite to the surface to which the piezoelectric body 13 is bonded. The front end surface of the comb tooth portion 12 a is in pressure contact with the rotor 15 and serves as a drive surface that drives the rotor 15. A lubricious polymer film such as an epoxy resin is formed on the driving surface. The reason for providing the comb tooth portion 12a is that the neutral surface of the progressive vibration wave (hereinafter referred to as traveling wave) generated on the drive surface due to the expansion and contraction of the piezoelectric body 13 is as close as possible to the piezoelectric body 13 side. This is to amplify the amplitude of the traveling wave.

The base portion 12b is a portion that is continuous in the circumferential direction of the elastic body 12, and the piezoelectric body 13 is bonded to the surface of the base portion 12b opposite to the comb tooth portion 12a.
The flange portion 12 c is a collar-shaped portion that is provided on the inner diameter side of the base portion 12 b and protrudes in the inner diameter direction of the elastic body 12. The stator 11 is fixed to the fixing member 16 by the flange portion 12c.

The piezoelectric body 13 is an electromechanical conversion element that converts electrical energy into mechanical displacement. For example, a piezoelectric element or an electrostrictive element is used. The piezoelectric body 13 is divided into ranges in which electric signals of two phases (A phase and B phase) are input along the circumferential direction of the elastic body 12. In each phase, elements in which polarization is alternated every ½ wavelength are arranged, and an interval of ¼ wavelength is provided between the A phase and the B phase.
The flexible printed circuit board 14 is connected to the electrodes of each phase of the piezoelectric body 13. The piezoelectric body 13 performs an expansion / contraction operation by a drive signal supplied via the flexible printed board 14. In the stator 11, traveling waves are generated on the drive surface of the elastic body 12 by the expansion and contraction of the piezoelectric body 13.

  The rotor 15 is a member that is made of a light metal such as aluminum and is rotationally driven by a traveling wave generated on the drive surface of the elastic body 12. In the rotor 15, a surface treatment such as anodizing treatment for improving wear resistance is performed on a contact surface with respect to the stator 11 (drive surface of the elastic body 12).

The output shaft 18 is provided through the inner diameter side of the stator 11 and the rotor 15, and the gear 4 is attached to one end portion. The other end of the output shaft 18 is in contact with the rotor 15 via the rubber member 23 and rotates integrally with the rotor 15.
The rubber member 23 is a substantially ring-shaped member made of a rubber-based material. The rubber member 23 has a function of allowing the rotor 15 and the output shaft 18 to be rotated together by viscoelasticity of rubber, and a function of absorbing the vibration so as not to transmit the vibration from the rotor 15 to the output shaft 18. But, butyl rubber, silicon rubber, propylene rubber and the like are used.

The pressure member 19 is a member that generates a pressing force that pressurizes and contacts the stator 11 and the rotor 15, and is provided between the gear 4 and the bearing receiving member 21. In the present embodiment, the pressing member 19 uses a coil spring, but is not limited thereto.
The gear 4 is inserted so as to fit in the D cut of the output shaft 18, is fixed by a stopper 22 such as an E ring, and is provided so as to be integrated with the output shaft 18 in the rotation direction and the axial direction.
Further, the bearing receiving member 21 is arranged on the inner diameter side of the bearing 17, and the bearing 17 is arranged on the inner diameter side of the fixed member 16.
The pressurizing member 19 pressurizes the rotor 15 toward the stator 11 in the axial direction of the output shaft 18. The rotor 15 is brought into pressure contact with the driving surface of the stator 11 by this applied pressure, and is driven to rotate. The spring constant of the pressure member 19 is set so that the contact surface pressure generated between the drive surface of the stator 11 and the contact surface of the rotor 15 is, for example, about 6 to 15N. A pressure adjusting washer may be provided between the pressure member 19 and the bearing receiving member 21 so that an appropriate pressure for driving the ultrasonic motor 10 can be obtained.

Here, the configuration of the rotor 15 will be described.
FIG. 3 is an enlarged view of a main part showing a rotor provided in the ultrasonic motor shown in FIG.
The rotor 15 includes a main body portion 30, a contact portion 31, and a connection portion 32.
The main body portion 30 is formed in an annular shape (cylindrical shape), and the output shaft 18 passes through the inner diameter side thereof. The rubber member 23 is in contact with one end of the main body 30.
The contact portion 31 is formed in an annular shape (cylindrical shape) having an inner diameter dimension larger than the outer diameter dimension of the main body portion 30, and one end portion thereof is in contact with the stator 11 (drive surface of the elastic body 12). It is a surface (sliding surface).

The connecting portion 32 is a portion that connects the other end of the main body 30 and the other end of the contact portion 31. The connection portion 32 is a circular plate-like portion that extends in a direction substantially parallel to the contact surface of the contact portion 31 when the rotor 15 is not pressurized by the pressure member 19.
The main body part 30, the contact part 31, and the connection part 32 are integrally formed by cutting a metal material, for example.

The rotor 15 is pressurized against the stator 11 by the pressure member 19. In this pressurized state, the connection part 32 formed in a circular plate shape is bent with respect to the main body part 30 and the contact part 31, respectively, as shown in FIG.
In addition, since the contact portion 31 has a structure that is cantilevered and supported by the main body portion 30 by the connection portion 32, a region on the inner diameter side of the contact surface (sliding surface) of the contact portion 31 with respect to the elastic body 12 is an elastic body. 12 is in contact with the drive surface, and the region on the outer diameter side is separated from the drive surface of the elastic body 12.
As described above, since the ultrasonic motor 10 is configured such that only a part of the contact surface of the contact portion 31 is in contact with the drive surface of the elastic body 12, the ultrasonic motor 10 is caused by a narrow contact area (concentration of applied pressure). There is a possibility that the stator 11 and the rotor 15 are fixed.

On the other hand, in the rotor 15 of the present embodiment, an angle formed by a plane orthogonal to the output shaft 18 (indicated by reference numeral P1 in FIG. 3) and a plane in which the connecting portion 32 extends (indicated by reference numeral P2 in FIG. 3). The dimensions of each part of the rotor 15 are set so that A1 is at least four times the angle A2 formed by the plane P1 and the plane including the contact surface of the contact portion 31 (indicated by reference numeral P3 in FIG. 3). Accordingly, the ultrasonic motor 10 prevents the stator 11 and the rotor 15 from sticking to each other.
More specifically, in the rotor 15 of the present embodiment, the angle A1 becomes four times the angle A2 by appropriately setting the thickness T of the connection portion 32 and the height H of the contact portion 31. It is adjusted.

  Table 1 shows the presence or absence of sticking in five types of ultrasonic motors in which the thickness T of the connection portion 32 and the height H of the contact portion 31 are changed.

As shown in Table 1, when the angle A1 is four times or more than the angle A2, the contact surface displacement difference D2 is small, and a relatively wide area of the contact surface is in contact with the drive surface of the elastic body 12. The contact surface displacement difference D2 means a difference in position between the inner peripheral edge and the outer peripheral edge of the contact surface in the axial direction of the output shaft 18. The angle A is obtained from the contact surface displacement difference D2 of the contact portion 31 and the radial length of the contact portion 31.
Further, the connection portion 32 is displaced in the axial direction of the output shaft 18 by the pressure contact between the rotor 15 and the stator 11. The amount of displacement differs between the inner peripheral side and the outer peripheral side of the connecting portion 32. The connecting portion displacement difference D1 means the difference between the amount of displacement at the inner peripheral edge of the connecting portion 32 in the axial direction of the output shaft 18 and the amount of displacement at the outer peripheral edge. The angle A1 is obtained from the connecting portion displacement difference D1 and the length of the connecting portion 32 in the radial direction.
And in order to make angle A1 into 4 times or more of angle A2, it is preferable to make height H of contact part 31 large with respect to thickness T of connecting part 32. As shown in Table 1, the height H of the contact portion 31 is preferably 2.2 times or more the thickness T of the connection portion 32.
And the ultrasonic motor with a wide contact area between the contact portion 31 and the elastic body 12 configured as described above does not cause the stator 11 and the rotor 15 to be fixed in any case shown in Table 1. The rotor 15 cannot be driven.

According to the lens barrel of the embodiment described above, the following effects can be obtained.
(1) The height of the contact portion 31 is set so that the angle A1 formed by the plane P1 orthogonal to the output shaft 18 and the direction in which the connection portion 32 extends is at least four times the angle A2 formed by the plane P1 and the contact surface. Since the height H and the thickness T of the connection portion 32 are set and the contact surface of the contact portion 31 with respect to the stator 11 is increased, the fixation between the stator 11 and the rotor 15 can be suppressed.
(2) Since the angle A1 is set to be four times or more the angle A2 by setting the thickness T of the connecting portion 32 and the height H of the contact portion 31, the basic performance of the ultrasonic motor 10 is deteriorated. It is possible to prevent the stator 11 and the rotor 15 from sticking to each other.
(3) Since the polymer film is formed on the contact surface of the stator 11 with the rotor 15, the sliding resistance between the stator 11 and the rotor 15 is reduced, and the energy loss can be reduced.

[Deformation]
The present embodiment is not limited to the embodiment described above, and various modifications and changes as described below are possible.
(1) In the ultrasonic motor of the embodiment, by appropriately setting the thickness of the connection portion and the height of the contact portion, an angle formed by a plane orthogonal to the output shaft and a direction in which the connection portion extends is The angle formed by the plane perpendicular to the output shaft and the contact surface is made larger. However, the present invention is not limited to this. For example, the rotor main body, contact, and connection are formed of different materials. The same effect as the embodiment may be obtained depending on the difference in the elastic modulus of the material. Further, for example, the pressing force of the pressurizing unit may be adjusted.
(2) Although the ultrasonic motor of the embodiment drives the focus lens provided in the lens barrel, the present invention is not limited thereto, and for example, a zoom lens or the like may be driven. In addition, the lens barrel is not limited to that used in a photographing apparatus such as a camera system, and may be used in other optical devices such as a microscope, binoculars, and a telescope.
(3) In the embodiment, the polymer film formed on the driving surface of the stator is an epoxy resin. However, the polymer film is not limited thereto, and may be formed of, for example, a phenol resin, a polyimide resin, a PEEK resin, or the like. Further, the drive surface of the stator may be subjected to a surface treatment such as Ni-P (nickel-phosphorus) plating.

It is a figure explaining the camera system of an embodiment. It is sectional drawing of the ultrasonic motor of embodiment. It is a principal part enlarged view which shows the rotor with which the ultrasonic motor shown in FIG. 2 was equipped.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Ultrasonic motor: 11 Stator: 15 Rotor: 18 Rotating shaft: 19 Pressurizing member: 30 Main part: 31 Contact part: 32 Connection part

Claims (5)

A stator formed in an annular shape;
A rotor having an annular contact surface in contact with the stator and rotating in response to vibration of the stator;
A pressurizing unit that pressurizes the stator and the rotor from a direction intersecting the contact surface;
The rotor is provided in a ring-shaped main body portion, a contact portion having the contact surface, and extending from the main body portion in a direction substantially parallel to the contact surface, and the main body portion and the contact portion. And a connecting portion for connecting
When the height of the contact portion is 2.2 times or more the thickness of the connection portion, the surface perpendicular to the rotation axis around which the rotor rotates and the connection portion are in a pressurized state by the pressure portion. The vibration actuator characterized in that an angle formed by the extending direction is at least four times an angle formed by a surface orthogonal to the rotation axis and a contact surface of the contact portion . The vibration actuator according to claim 1 ,
The vibration actuator, wherein the stator has a polymer film formed on a contact surface with the rotor. The vibration actuator according to claim 2 ,
The polymer actuator includes at least one of an epoxy resin, a phenol resin, a polyimide resin, and a PEEK resin. The vibration actuator according to any one of claims 1 to 3 ,
A lens barrel comprising: a lens interlocking with an output shaft provided in the vibration actuator. An optical apparatus comprising the vibration actuator according to any one of claims 1 to 3 .

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