JP2000275501A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the lens barrel which is easily assembled and inexpensive by equipping the lens barrel with a slider which is formed integrally with a lens frame and a cam follower which is formed integrally with the lens frame or slider. SOLUTION: A power varying lens 14 and a correcting lens 16 are supported on lens frames 22 and 24. The lens frames 22 and 24 have rod type sliders 22A and 24B formed integrally so as to make the lens frames 22 and 24 slidable along an optical axis L. The respective corresponding sliders 22A and 24B are fitted in rectilinear grooves 32A and 32B formed on the internal surface of the lens barrel 10. The lens frames 22 and 24 have the cam follower 25 formed in one body and a bush 26 for sliding is inserted into the cam follower 25 while circumscribed. This bush 26 is engaged with the cam groove 30 for power varying lens and the cam groove 34 for correcting lens of an external cam cylinder 28 through a slit 31 formed on the lens barrel 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel,
In particular, the present invention relates to a lens barrel capable of moving a lens along an optical axis of the lens barrel.

[0002]

2. Description of the Related Art In a zoom lens barrel having a variable power lens and a correction lens, a moving guide structure for the variable power lens and the correction lens is disclosed in Japanese Patent Laid-Open No. 4-285904. A method of guiding a frame with a plurality of guide bars is known. Also, two roller-type cam followers are radially provided at three places of the lens frame, and the first-stage cam followers are guided by straight grooves provided at three places of the lens barrel. There is known a method in which a guide is provided by a cam groove provided in a zoom cam cylinder circumscribing a lens barrel and disposed coaxially with the lens barrel.

[0003]

However, the conventional zoom lens barrel requires a large number of parts, and requires a complicated process and high precision adjustment for assembly. In addition, the optical axes of the variable power lens and the correction lens are shifted from the optical axis L due to the movement at the time of zooming, and there has been a phenomenon that a captured image is deteriorated. In order to improve the precision of the parts so that the deviation of the optical axis is reduced, a large processing cost is required.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an inexpensive lens barrel which can minimize the displacement of the optical axis when the lens moves. And

[0005]

According to the first aspect of the present invention, a lens provided inside a lens barrel is supported so as to be movable in an optical axis direction. In the lens barrel, at least one slider integrally formed on a lens frame holding the lens, at least one cam follower integrally formed on the lens frame or the slider, and provided on the lens barrel,
A cam groove provided with a straight groove for guiding the slider in the optical axis direction, and a cam groove for rotating the lens frame parallel to the optical axis while guiding the cam follower while rotating with respect to the lens barrel. It is characterized by having.

According to the first aspect of the present invention, in the lens barrel, at least one slider formed integrally with the lens frame holding the lens, and at least one slider formed integrally with the lens frame or the slider. Two cam followers, a rectilinear groove provided in the lens barrel, for guiding the slider in the optical axis direction, and rotating with respect to the lens barrel, guiding the cam follower so that the lens frame is parallel to the optical axis. And a cam barrel provided with a cam groove for moving the lens barrel, it is possible to provide an inexpensive lens barrel that is easy to assemble.

In order to achieve the above object, according to the invention described in claim 2 of the present application, the slider is constituted by a rod-shaped member having a predetermined length. According to the second aspect of the present invention, since the slider is a rod-shaped member having a predetermined length, the lens can be accurately moved along the optical axis. According to the third aspect of the present invention, in order to achieve the above object, both ends of the slider have a large diameter,
It is characterized in that both ends are in contact with the rectilinear grooves.

According to the third aspect of the present invention, since both ends of the slider have a large diameter and come into contact with the rectilinear grooves at both ends, the lens can be accurately moved along the optical axis without play. can do. According to the invention described in claim 4 of the present application, the width of the portion of the lens barrel according to claim 2 in which the slider engages with the rectilinear groove is the same as the width of the rectilinear groove. It is characterized by a material that is set wider than that and is a material that elastically deforms or a structure that elastically deforms.

According to the fourth aspect of the present invention, the width of the portion where the slider engages with the rectilinear groove is set wider than the width of the rectilinear groove, and the elastically deformable material or the elastically deformable structure is adopted. Therefore, the displacement of the optical axis during the movement of the lens can be suppressed to a small value, and an inexpensive lens barrel that can be easily assembled can be provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a lens barrel according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view of a zoom lens barrel 10 for a television camera to which a lens barrel according to the present invention is applied.

FIG. 2 is a perspective view showing a structure before assembling the lens barrel 10 shown in FIG. 1 and each main component. The lens barrel 10 shown in FIG. 1 includes a focus lens 12, a variable power lens 14, a correction lens 16, a relay lens 17, and a master lens 18 arranged in this order from the front with respect to the optical axis L. In the lens barrel 10, the focus lens 12 is large in order to realize a wider-angle shooting, and the zoom lens 14 and the correction lens 16 are zoom-movable in order to realize higher-magnification shooting. The range is set long.

The focus lens 12 is disposed at an opening at the front end of the lens barrel 10 and is provided so as to be movable back and forth along the optical axis L, and is moved back and forth by a driving mechanism such as a helicoid screw (not shown). Thereby, focus adjustment is performed. The variable power lens 14 is supported by a lens frame 22. The lens frame 22 has a rod-shaped slider 22 for allowing the lens frame 22 to slide along the optical axis L.
A is integrally formed, and a plurality of A are provided. The correction lens 16 is supported by a lens frame 24. The lens frame 24 is integrally formed with a plurality of rod-shaped sliders 24B for enabling the lens frame 24 to slide along the optical axis L, and a plurality of sliders 24B are provided.

The inner surface of the lens barrel 10 has a plurality of straight grooves 3.
2A, 32B,...
The sliders 22A, 24B,.
(See FIGS. 1 and 2). Straight grooves 32A, 32
B are formed in parallel with the optical axis L,
And 16 are slidable along the optical axis L. A cam follower 25 is formed integrally with the lens frame 22,
A bush 26 formed of a sliding material such as resin is circumscribed in the cam follower 25. The bush 26 is engaged with a variable-lens lens cam groove 30 of the outer cam cylinder 28 via a slit 31 (see FIGS. 1 and 2) formed in the lens barrel. Similarly, a cam follower 25 is integrally formed with the lens frame 24 of the correction lens 16.
Is inserted. The bush 26 is engaged with the correction lens cam groove 34 of the outer cam cylinder 28 via the slit 31. The spur gear 40 connected to the outer cam cylinder 28 and the pinion gear 42 engaged with the output shaft 38 of the motor 36 mesh with each other.

FIG. 3 is a development view of the outer periphery of the outer cam cylinder 28. According to FIG. 3, the cam grooves 30 for the variable power lens of the outer cam barrel 28 and the cam grooves 34 for the correction lens
Six introduction grooves 30a and 34a are formed, and one end is open. The introduction grooves 30a and 34a are
And a bush 26 for facilitating assembly when the lens frame 24 and the lens frame 24 are assembled to the lens barrel 10.

The procedure for assembling the main components of the zoom lens to the lens barrel 10 will be described below with reference to FIG.
In assembling the zoom lens system of the lens barrel 10, parts are assembled from the front of the lens barrel 10. First, outer cam cylinder 2
8 is attached to the lens barrel 10 and rotated, and the lens barrel 1 is rotated.
The angle is adjusted so that the position of the slit 31 of 0 and the position of the introduction groove 34a coincide. The sliders 24B of the lens frame 24, 24B ...
Are fitted into the predetermined rectilinear grooves 32B, 32B,..., And the lens frame 24 is advanced to the back along the inner surface of the lens barrel 10. At this time, the bush 26 advances along the introduction groove 34a, reaches the cam groove 34 for the correction lens, and inserts the bush 26 to a position where it cannot be further advanced.

Next, the outer cam barrel 28 is rotated so that the slit 31 of the lens barrel 10 and the position of the introduction groove 30a coincide with each other. A slider 22A of the lens frame 22,
Are inserted into predetermined straight grooves 32A, 32A,
The lens frame 22 is advanced along the inner surface of the lens barrel 10. At this time, the bush 26 advances along the introduction groove 30a and reaches the correction lens cam groove 34. This completes the assembly of the zoom lens system.
2 and a focus system component (not shown) are assembled.

A situation in which the magnification is changed from WIDE (wide angle) to TELE (telephoto) using the zoom lens barrel configured as described above will be described. Output shaft 3 of motor 36
When the lens 8 is driven forward / reverse, the variable power lens 14 moves back and forth in the optical axis L direction along the locus of the cam groove 30. Similarly, the correction lens 16 moves back and forth in the optical axis L direction along the locus of the cam groove 34. Since the variable power lens 14 and the correction lens 16 have positive power, WIDE (wide angle) photographing can be performed at the position where the variable power lens 14 and the correction lens 16 are farthest away, and TELE is performed at the closest position. (Telephoto) You can shoot.

Incidentally, the variable power lens 14 and the correction lens 1
As described above, the zoom movement range of the zoom lens 6 is set to be long in order to enable shooting at a higher magnification. For this reason, the slider 22A of the lens frame 22 of the variable power lens 14
.. And the sliders 24B, 24B of the lens frame 24 of the correction lens 16 may interfere when moved to the closest position. Are formed at positions where they do not interfere with each other, and are fitted into separate linear grooves 32A, 32B, respectively.

However, if the cam followers 25, 25 use one straight groove, the accuracy is improved and the processing of the lens barrel 10 is easy. Therefore, the cam follower 2
5 and 25 are fitted in the slit 31 which is the same straight groove. From the above, the cam followers 25, 2
5 is a slider 22A, 22A or a slider 24B,
24B are arranged at positions slightly deviated from the uniform positions between the respective 24B.

The variable power lens 1 which is movable
If the optical axis of the correction lens 16 and the optical axis of the correction lens 16 are shifted from the optical axis L due to the movement at the time of zooming, this will appear as a deterioration phenomenon of the captured image. Therefore, the variable power lens 14 and the correction lens 1
It is necessary to move straight ahead with high precision so that the optical axis of 6 does not shift as much as possible. For this purpose, the clearance between the rectilinear grooves 32A, 32B... Formed on the inner surface of the lens barrel 10 and the sliders 22A, 24B.

FIGS. 4 and 5 show the linear groove 32 and the slider 2 respectively.
3 and 3 show a configuration for eliminating clearance with 23A. FIG.
The width Wa of the slider 23 constituted by the elastic member shown in FIG. 1 is set to be equal to or larger than the width W of the rectilinear groove 32. When the slider 23 is fitted into the rectilinear groove 32, the width of the slider 23 is elastically deformed and corrected to the width W, so that the clearance can be eliminated. The setting of the amount of deformation at this time is determined according to the physical properties and shape related to the force required when the slider 23 elastically deforms, and the frictional force generated between the slider 23 and the rectilinear groove 32. When a resin molded product is used as the material of the slider 23, the shape of the deformed portion and the integrated structure with the lens frame can be easily and accurately achieved, and a dimensional error during molding is absorbed by the deformation of the slider 23. can do. Therefore, the displacement of the optical axis during the movement of the lens can be suppressed to a small value, and the assembling is easy, so that an inexpensive lens barrel can be provided.

The means for eliminating the clearance shown in FIG.
When the slider 23A is provided with a flexible portion that can be elastically deformed, and the slider 23A having a width Wa is fitted into the rectilinear groove 32 having a width W, the width of the slider 23A is bent and corrected to the width W. Can be. The setting of the amount of deformation at this time is determined according to the physical properties and shape of the elastic coefficient of the slider 23A and the frictional force generated between the slider 23A and the rectilinear groove 32. By setting such a shape of the slider 23A, the same effect as that of the embodiment shown in FIG. 4 can be obtained, and the material is not only a resin molded product but also a cast product represented by a metal die cast or the like. Can also be used.

In this embodiment, the variable magnification structure of the lens barrel 10 applied to a television camera has been described. However, the present invention may be applied to a general camera using a photographic film. The present invention may be applied to a focus structure and other lens moving structures. Further, in the present embodiment, the cam follower 25 has been described as an example integrally formed with the lens frames 22, 24 separately from the sliders 22A, 24B.
The present invention is not limited to this. Even if the cam follower 25 is integrally formed on the sliders 22A and 24B, the object of the present invention can be achieved. In this case, one of the straight grooves 32A and 32B is made common to the slit 31.

In the present embodiment, the cam barrel used for zooming is described as an outer cam type. However, the present invention is not limited to this, and the present invention is not limited to this. May be applied to the cam ring system.

[0025]

As described above, according to the lens barrel of the present invention, by forming the slider on the lens frame, the displacement of the optical axis during the movement of the lens can be suppressed and the assembly is easy. It is possible to provide an inexpensive lens barrel.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a zoom lens barrel for a television camera to which a lens barrel according to the present invention is applied.

FIG. 2 is a perspective view showing a configuration of the lens barrel shown in FIG. 1 before assembling each main component.

FIG. 3 is an outer peripheral development view of the outer cam cylinder.

FIG. 4 is a diagram showing a configuration for eliminating a clearance between a straight groove and a slider.

FIG. 5 is a diagram showing a configuration for eliminating a clearance between a rectilinear groove and a slider.

[Explanation of symbols]

Reference numeral 10: lens barrel, 12: focus lens, 14: variable power lens, 16: correction lens, 22: lens frame, 22A
... Slider, 23, 23A ... Slider, 24 ... Lens frame, 24B ... Slider, 25 ... Cam follower, 28 ... Outer cam cylinder, 30 ... Cam groove, 32, 32A, 32B ... Straight groove, 34 ... Cam groove

Claims (4)

[Claims] A lens provided inside the lens barrel, the lens barrel being designated to be movable in an optical axis direction, wherein at least one slider formed integrally with a lens frame holding the lens; At least one cam follower integrally formed with the lens frame or the slider; a straight groove provided in the lens barrel for guiding the slider in an optical axis direction; and rotating with respect to the lens barrel. A lens barrel provided with a cam groove for guiding the cam follower to move the lens frame in parallel with the optical axis. 2. The lens barrel according to claim 1, wherein said slider comprises a rod-shaped member having a predetermined length. 3. The lens barrel according to claim 2, wherein both ends of the slider have a large diameter, and the both ends contact the straight groove. 4. A portion where the slider engages with the rectilinear groove is set to have a width larger than a width of the rectilinear groove, and is made of a material that is elastically deformed or a structure that is elastically deformed. The lens barrel according to claim 2, wherein