Thrust clearance adjustment device of optical component

Abstract

To provide a thrust clearance adjustment device of an optical component which can maintain the rotary operation performance or the optical performance by keeping an appropriate clearance in the direction of an optical axis of an optical component which is positioned in the direction of an optical axis and is rotary-operated.SOLUTION: A clearance adjustment unit 8 is provided in plural parts in a circumferential direction in an end surface of a diaphragm linkage ring 6 in the direction of the optical axis. When the diaphragm linkage ring 6 is rotary-operated, the clearance adjusting units 8a are slid and rotated while a steel ball 8b is being pressed against a facing wall 4a.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a thrust clearance adjustment device for optical components incorporated in an imaging device such as a camera or a projector. [Background technology]

[0002] Imaging devices such as cameras and projectors are provided with optical components that require rotation, such as an aperture adjustment ring for adjusting the aperture and a focus ring for moving a lens group forward and backward along the optical axis. Since an imaging device has many optical components assembled along the optical axis direction, the clearance in the optical axis direction is likely to vary due to the accumulation of tolerances between the optical components. In particular, optical components that are rotated require a clearance in the optical axis direction necessary for the rotation, but there is a risk that play caused by excess clearance will cause sliding noise and affect the accuracy of opening and closing the aperture and the accuracy of the focus amount.

[0003] For this reason, in order to adjust the clearance in the optical axis direction of the optical components that are rotated, a number of annular washers (shims) 51 of different thicknesses are prepared, and as shown in Figure 5, washers 51 of a specified thickness are interposed between a fixed member 52 and a rotation operation member 53 that faces it in the optical axis direction, to absorb variations in the clearance in the optical axis direction due to the accumulation of tolerances among the many optical components.

[0004] In a zoom lens barrel in which the distance between lens groups in the optical axis direction is changed by the rotation of a cam barrel with a cam groove provided on the circumferential surface, the clearance in the optical axis direction between the cam barrel and a cam holding frame provided at the end of the fixed barrel fluctuates in response to changes in the environmental temperature.To suppress this clearance fluctuation, a structure has been proposed in which an annular elastic piece is provided between the end of the cam barrel and the cam holding frame to absorb the backlash of the cam barrel in the optical axis direction (JP Patent Publication 2001-243906). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 3-243906 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if multiple washers 51 with different thicknesses are prepared in advance as shown in FIG. 5, a mold must be made, which is costly, and every time a washer 51 is replaced, an adjustment process is required in which the optical components are disassembled and reassembled, which is time-consuming. Furthermore, as in Patent Document 1, sandwiching an elastic member between the end of the cam barrel that is rotated and the opposing cam holding frame increases sliding resistance, making rotational operability poor, and there is also the risk of the clearance in the optical axis direction fluctuating due to deformation of the elastic member. [Means for solving the problem]

[0007] An object of the present invention is to solve the problems of the conventional technology described above and to provide a thrust clearance adjustment device for an optical component that can maintain rotational operability and optical performance by properly maintaining the clearance in the optical axis direction of an optical component that is positioned in the optical axis direction and rotated.

[0008] In order to solve the above problems, a thrust clearance adjustment device for an optical component applied to the present invention has the following configuration. A thrust clearance adjustment device for an optical component in which an optical component arranged concentrically with a lens barrel is rotated around the optical axis while being positioned with a predetermined clearance in the optical axis direction, wherein a recess is provided on the end face in the optical axis direction of the optical component, and clearance adjustment sections are provided at multiple locations around the circumferential direction of the optical component, in which a coil spring is loaded compressed from its natural length and a steel ball connected to the end of the spring is constantly pressed against an opposing fixed wall along the optical axis, and when the optical component is rotated, each of the steel balls slides and rotates while being pressed against the opposing fixed wall. According to the above configuration, the clearance adjustment parts are provided at multiple locations in the circumferential direction on the end surface in the optical axis direction of the optical component, and when the optical component is rotated, the steel balls slide and rotate while being pressed against the fixed wall. Therefore, the coil spring absorbs the variation in the clearance in the thrust direction caused by the accumulation of tolerances between many optical components, and there is no need to replace parts to adjust the thrust clearance of the optical component, reducing the cost of adjusting parts and their manufacturing, and reducing the adjustment process. In addition, by properly maintaining the thrust clearance of the optical component that is rotated, it is possible to maintain the rotational operability and optical performance.

[0009] The clearance adjustment portions may be provided at three or more locations at equal intervals in a circumferential direction on an end surface of the optical component in the optical axis direction. This makes it possible to maintain stable rotational operability and optical performance by adjusting the clearance in the optical axis direction using clearance adjustment sections provided at three or more equally spaced locations circumferentially on the optical axis end face of the optical component.

[0010] The opposing fixed wall against which the steel ball is constantly pressed may be flat or concave. This allows the steel ball to easily slide and rotate while being pressed against the opposing fixed wall, improving the ease of rotation of the optical component.

[0011] The optical component may be an aperture linkage ring that links with an aperture adjustment ring that changes the aperture diameter, and a clearance adjustment portion provided on the end face of the aperture linkage ring in the optical axis direction may be such that a steel ball is constantly pressed against a fixed wall of the opposing front frame base, so that the aperture linkage ring is positioned with a predetermined clearance between it and the front frame base in the optical axis direction. This prevents the rotary sliding noise of the aperture linkage ring, which rotates in conjunction with the rotation of the aperture adjustment ring, from being generated, and by maintaining an appropriate clearance in the optical axis direction, the opening and closing precision of the aperture diameter of the aperture blades can be maintained.

[0012] The optical component may be a focus ring that moves a lens assembly arranged inside a lens barrel in the optical axis direction, and a clearance adjustment portion provided on an end face of the focus ring in the optical axis direction may be configured such that the steel ball is constantly pressed against a fixed wall of the opposing fixed cylinder, thereby positioning the focus ring with a predetermined clearance between it and the fixed cylinder in the optical axis direction. As a result, no rotary sliding noise is generated when the focus ring is rotated, and the focus accuracy of the lens assembly can be maintained by maintaining an appropriate clearance in the optical axis direction. Effect of the Invention

[0013] It is possible to provide an optical component thrust clearance adjustment device that can maintain rotational operability and optical performance by properly maintaining the clearance in the optical axis direction of an optical component that is positioned in the optical axis direction and rotated. [Brief description of the drawings]

[0014] [Figure 1] 1 is a half cross-sectional view of an interchangeable lens showing an example of a thrust clearance adjustment device for an optical component. [Diagram 2] 2 is an explanatory diagram showing the arrangement of the clearance adjustment portion in FIG. 1, as viewed from the front in the optical axis direction. FIG. [Diagram 3] FIG. 4 is an enlarged cross-sectional view of a clearance adjustment portion. [Figure 4] 11 is a half cross-sectional view of an interchangeable lens showing another example of a thrust clearance adjustment device for an optical component. FIG. [Diagram 5] FIG. 10 is an explanatory diagram of a conventional thrust clearance adjustment portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Example 1] An embodiment of a thrust clearance adjustment device for an optical component according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a half cross-sectional view of an interchangeable lens 1 that can be used in a digital camera such as a single-lens reflex camera. The interchangeable lens 1 includes a lens barrel 2 including a fixed cylinder portion 2a. A plurality of lens support frames 2b1, 2b2 are provided on the outside and inside of the fixed cylinder portion 2a, and a plurality of lens bodies L are supported on the inner peripheral surfaces of the lens support frames 2b1, 2b2 (lens bodies on the lens support frame 2b2 side are not shown). In addition, this type of interchangeable lens 1 is usually equipped with a manual or automatic focusing adjustment mechanism and a zoom adjustment mechanism.

[0016] 1, an aperture adjustment ring 3 is rotatably provided on the outer circumferential surface of a lens barrel 2. By rotating this aperture adjustment ring 3, the aperture opening diameter formed by multiple aperture blades can be changed as desired. The aperture adjustment ring 3 is restricted in its displacement in the optical axis direction between a front frame base 4 that is screwed to the front end of the fixed tube portion 2a and a protruding wall 2c that protrudes radially outward from the fixed tube portion 2a, and can only be rotated in the circumferential direction. A filter frame 5 is fixed by screws to the front of the front frame base 4. A lens holding portion 2b1 is provided on the filter frame 5, and a lens holding frame 2b2 is provided inside the fixed cylinder portion 2a, and each of the lens bodies L is held by the lens holding frame 2b2.

[0017] An aperture interlocking ring 6 (optical component) is provided concentrically inside the fixed tube portion 2a. The aperture interlocking ring 6 is integrally connected to the aperture adjustment ring 3 by radially engaging with each other. An annular chrysanthemum washer 2d is provided inside the aperture interlocking ring 6 of the fixed tube portion 2a, protruding radially inward. An aperture blade mechanism M is provided behind the chrysanthemum washer 2d. This aperture blade mechanism M is composed of a plurality of aperture blades (not shown) arranged at equal intervals in the circumferential direction. The aperture blade mechanism M has at least 10 or more aperture blades arranged in the circumferential direction inside the lens barrel 2, one end of which is rotatably supported, and the other end of which is rotated and displaced along a cam groove provided in the chrysanthemum washer 2d to change the size of the aperture opening in cooperation with the aperture interlocking ring 6. When the aperture adjustment ring 3 is rotated, the aperture interlocking ring 6 also rotates in conjunction with the aperture interlocking ring 6, and the size of the aperture opening changes due to the rotational displacement of the aperture blades.

[0018] As shown in Fig. 3, a recess 6a is provided on the front end surface of the aperture interlocking ring 6 in the optical axis direction. A coil spring 8a is loaded in the recess 6a compressed from its natural length, and a steel ball 8b connected to the end of the spring is constantly pressed against the opposing wall 4a (fixed wall) of the front frame base 4 that faces along the optical axis direction (clearance adjustment portion 8). This clearance adjustment portion 8 is provided at multiple locations (for example, three locations as shown in Fig. 2) in the circumferential direction of the aperture interlocking ring 6. In this way, the aperture interlocking ring 6 is positioned with a predetermined clearance between it and the front frame base 4 in the optical axis direction. When the aperture adjustment ring 3 is rotated, the aperture interlocking ring 6 also rotates in conjunction with the rotation, and the steel ball 8b slides and rotates while being pressed against the opposing wall 4a.

[0019] 2, the clearance adjustment parts 8 may be provided at three or more equally spaced locations in the circumferential direction on the front end face of the aperture-interlocking ring 6. In this way, by adjusting the clearance in the optical axis direction with the clearance adjustment parts 8 provided at three equally spaced locations in the circumferential direction on the end face of the aperture-interlocking ring 6 in the optical axis direction, stable rotational operability and optical performance can be maintained.

[0020] In addition, the facing wall 4a against which the steel ball 8b is pressed may be flat or concave. This allows the steel ball 8b to slide and rotate easily while being pressed against the opposing wall 4a, and the aperture interlocking ring 6 is easy to rotate without generating a rotational sliding sound.

[0021] As described above, the coil spring 8a absorbs the variation in clearance in the optical axis direction caused by the accumulation of tolerances between the many optical components in the interchangeable lens 1, and there is no need to replace washers or other components for adjusting the clearance of the aperture interlocking ring 6, reducing the cost of adjustment components and their manufacturing costs, and reducing the adjustment process. Also, by properly maintaining the clearance in the optical axis direction of the optical components that are rotated, it is possible to maintain rotational operability and optical performance.

[0022] [Example 2] Next, a focus ring 9 will be described as another example of an optical part that is rotated. Fig. 4 is a half cross-sectional view of an interchangeable lens 1 that includes a focusing adjustment mechanism. As shown in Fig. 4, the optical part may be a focus ring 9 that moves a lens assembly arranged inside a fixed cylinder in the optical axis direction.

[0023] The focus ring 9 is provided between a first fixed barrel 10 and a second fixed barrel 11 arranged in the optical axis direction. Specifically, the focus ring 9 is positioned in the optical axis direction with a front end face 9b abutted against the first fixed barrel 10 and a predetermined clearance provided between the rear end face 9c and the second fixed barrel 11. A recess 9a is provided on the rear end face 9c in the optical axis direction of the focus ring 9. A coil spring 8a is loaded in the recess 9a compressed from its natural length, and a steel ball 8b connected to the spring end is constantly pressed against an opposing wall 11a (fixed wall) of the second fixed barrel 11 facing along the optical axis direction (clearance adjustment unit 8). This clearance adjustment unit 8 is provided at multiple locations (for example, three locations as shown in FIG. 2) in the circumferential direction of the focus ring 9. In this way, the focus ring 9 is positioned between the first fixed barrel 10 and the second fixed barrel 11 with a predetermined clearance provided between the second fixed barrel 11 and the first fixed barrel 10 in the optical axis direction. Incidentally, the facing wall 11a against which the steel ball 8b is constantly pressed is a flat surface, but it may be a concave surface.

[0024] A first lens holding part 12a constituting the first lens assembly L1 is provided inside the first fixed barrel 10. A movable barrel 12b extending in the optical axis direction is provided on the outer periphery of the first fixed barrel 10. A screw groove is provided on the inner periphery of the movable barrel 12b, which is screw-fitted with a screw groove provided on the outer periphery of a cylindrical helicoid member 13. The focus ring 9 holds a rotation interlocking key 14 extending along the optical axis direction. The rotation interlocking key 14 is slidably fitted into a linear groove formed along the optical axis direction on the outer periphery of the helicoid member 13. When the rotation interlocking key 14 slides along the linear groove, the helicoid member 13 advances or retreats while rotating. This helicoid member 13 is provided on the outer periphery of the first fixed barrel 10 so as to be slidable and rotatable. A first linear groove (not shown) is provided on the first fixed barrel 10 along the optical axis direction. In the first rectilinear groove, a first roller 12c rotatably supported by the first lens holding portion 12a is assembled so as to be capable of rolling and moving along the optical axis direction.

[0025] When the focus ring 9 is rotated, the helicoid member 13 moves in the optical axis direction while rotating via the rotation interlocking key 14. At this time, the first lens holding part 12a moves in the optical axis direction while rotating via the movable barrel 12b that is screw-fitted with the helicoid member 13, but because the first roller 12c is fitted into the first rectilinear groove of the first fixed barrel 10 and its rotation is restricted, the first lens holding part 12a does not rotate, and the first roller 12c rolls in the first rectilinear groove in the optical axis direction to move forward or backward.

[0026] A second lens holding portion 12d constituting a second lens assembly L2 is provided behind the first lens assembly L1 in the first fixed barrel 10. A cam groove (not shown) is provided on the inner peripheral surface of the helicoid member 13 in a direction perpendicular to the optical axis direction, and a second linear groove (not shown) is provided along the optical axis direction in the first fixed barrel 12 facing the cam groove. A second roller (not shown) rotatably supported by the second lens holding portion 12d is assembled in the cam groove and the second linear groove so as to be able to roll along the optical axis direction.

[0027] When the focus ring 9 is rotated, the helicoid member 13 moves in the optical axis direction while rotating via the rotation interlocking key 14. At this time, the second roller is fitted into the second rectilinear groove of the first fixed barrel 10 and its rotation is restricted, so the second lens holding portion 12d does not rotate and the second roller rolls in the second rectilinear groove in the optical axis direction to move forward or backward.

[0028] In this way, when the focus ring 9 is rotated, the helicoid member 13 is rotated via the rotation interlocking key 14, but the first lens holding part 12a and the second lens holding part 12d are both restricted in rotation by the first fixed barrel 10 and move forward or backward along the optical axis direction. This changes the distance in the optical axis direction from the first lens assembly L1 and the second lens assembly L2 to the object, allowing focus adjustment.

[0029] When the focus ring 9 is rotated, the steel ball 8b is constantly pressed against the opposing wall 11a and slides and rotates in the optical axis direction while maintaining a predetermined clearance between the second fixed cylinder 11 and the ring 8b. Therefore, the rotation of the focus ring 9 does not generate a rotational sliding sound, and the focus accuracy can be maintained by maintaining an appropriate clearance in the optical axis direction.

[0030] As described above, the clearance adjustment parts 8 are provided at multiple locations in the circumferential direction on the end surfaces of optical components in the optical axis direction, such as the aperture adjustment ring 6 and the focus ring 9, and when these optical components are rotated, the steel balls 8b slide and rotate while being pressed against the opposing wall. Therefore, the coil spring 8a absorbs the variation in the clearance in the optical axis direction due to the accumulation of tolerances between optical components, and there is no need to replace parts for adjusting the clearance of the optical components, reducing the cost of adjusting parts and their manufacturing, and also reducing the adjustment process. In addition, by properly maintaining the clearance in the optical axis direction of the optical components that are rotated, it is possible to maintain the rotational operability and optical performance.

[0031] In each of the above-described embodiments, the imaging device is not limited to the interchangeable lens 1 for a camera, but may be a lens for a projector, etc. Also, the number of aperture blades provided in the aperture blade mechanism M may be either 10 or more or 10 or less. [Explanation of symbols]

[0032] 1 interchangeable lens 2 lens barrel 2a fixed barrel portion 2b1, 2b2 lens support frame 2c protruding wall 2d star washer L lens body 3 aperture adjustment ring 4 front frame base 4a, 11a opposing wall 5 filter frame 6 aperture interlocking ring 6a, 9a recess M aperture blade mechanism 8 clearance adjustment portion 8a coil spring 8b steel ball 9 focus ring 10 first fixed barrel 11 second fixed barrel L1 first lens assembly L2 second lens assembly 12a first range holding portion 12b movable barrel 12c first roller 12d second lens holding portion 13 helicoid member 14 rotation interlocking key

Claims

1. An optical component thrust clearance adjustment device in which an optical component arranged concentrically with a lens barrel is rotated about an optical axis while being positioned with a predetermined clearance in the optical axis direction, a recess is provided on the end face of the optical component in the optical axis direction, a coil spring is loaded into the recess compressed from its natural length, and a steel ball connected to the end of the spring is constantly pressed against an opposing fixed wall along the optical axis, so that clearance adjustment sections are provided at a plurality of locations around the circumference of the optical component, and when the optical component is rotated, the steel balls each slide and rotate while being pressed against the opposing fixed wall.

2. 2. The thrust clearance adjusting device for an optical component according to claim 1, wherein the clearance adjusting portions are provided at three or more positions at equal intervals in a circumferential direction on the end surface of the optical component in the optical axis direction.

3. 2. The thrust clearance adjusting device for an optical component according to claim 1, wherein the opposing fixed wall against which the steel ball is constantly pressed is flat or concave.

4. The optical component is an aperture linkage ring that links with an aperture adjustment ring that changes the aperture diameter, and a clearance adjustment portion provided on the end face of the aperture linkage ring in the optical axis direction is constantly pressed against a fixed wall of the opposing front frame base by a steel ball, so that the aperture linkage ring is positioned with a predetermined clearance between it and the front frame base in the optical axis direction.

5. 3. The thrust clearance adjustment device for optical components according to claim 1 or 2, wherein the optical component is a focus ring that moves a lens assembly arranged inside a lens barrel in the optical axis direction, and a clearance adjustment portion provided on an end face of the focus ring in the optical axis direction is configured so that the steel ball is constantly pressed against a fixed wall of the opposing fixed cylinder, thereby positioning the focus ring with a predetermined clearance between the focus ring and the fixed cylinder in the optical axis direction.

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