JP2593603Y2 - Zoom lens barrel - Google Patents

Description

[Detailed description of the invention]

[0001]

TECHNICAL FIELD The present invention relates to a zoom lens barrel.

[0002]

2. Description of the Related Art Various types of zoom lens barrels are known, but these basically form a cam groove on a cam ring for determining the movement locus of a movable lens group. Was. However, precise machining of the cam groove is expensive. For this reason, it was generally recognized that zoom lens barrels were expensive.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a zoom lens barrel which can be provided at a low cost with a simple structure.

[0004]

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a zoom lens barrel having two front and rear lens groups.
A fixed barrel having a mount mounted to the camera body at the rear end; a front lens support barrel fitted to the outer peripheral surface of the fixed barrel so as to be able to linearly advance and retreat in the optical axis direction; and support the front lens group A focus ring screwed into the front lens support cylinder;
A zoom ring, which is rotatably fitted directly to the outer peripheral surface of the front lens support cylinder, and which is integrally rotated; and an end surface of the front lens support cylinder, and an inner peripheral step portion at an intermediate portion of the zoom ring. An end surface cam mechanism for the front group formed between the front group lens; a rotating cylinder supporting the rear group lens and rotating integrally with the zoom ring, directly fitted to the inner peripheral surface of the fixed cylinder; And a rear group end face cam mechanism formed between the end face of the fixed cylinder and a part of the fixed cylinder.

According to a second aspect of the present invention,
In a zoom lens barrel having two front and rear lens groups, a fixed barrel having a mount mounted to a camera body at a rear end; and a linearly movable reciprocatingly movable in the optical axis direction on an outer peripheral surface of the fixed barrel. A combined front lens support cylinder; a focus ring that supports the front lens group and is screwed to the front lens support cylinder; all that is directly rotatably fitted to the outer peripheral surface of the front lens support cylinder. A zoom ring that rotates integrally; a front-group end cam mechanism formed between an end surface of the front-group lens support cylinder and an inner peripheral step portion of an intermediate portion of the zoom ring; A rear group lens frame which is directly fitted to the inner peripheral surface of the fixed barrel so as to be able to advance and retreat in the optical axis direction; and a turn which is integrally fitted to the inner peripheral surface of the fixed barrel and rotates together with the zoom ring. A moving cylinder; an end face of the rotating barrel and a part of the fixed barrel, or between an end face of the rotating barrel and an end face of the rear lens frame. It is characterized by comprising; a group for end cam mechanism after being made.

In any of the embodiments, the front group end cam and the rear group end cam move the two front and rear lens groups in the optical axis direction in a predetermined relationship with the rotation of the zoom ring to perform zooming. .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 8 shows an optical system of a zoom lens used in the lens barrel group of the present invention. This optical system includes two groups, a front lens group L1 and a rear lens group L2.
(A) shows the shortest focal length (for example, 38 mm). From this state, when the front lens group L1 and the rear lens group L2 are moved forward with a predetermined relationship between them, the focal length becomes the intermediate focal length. The distance (50 mm) (B) and the longest focal length (60 mm) (C) change. At any focal length, focusing is performed by adjusting the position of the front lens unit L1 in the optical axis direction.

FIGS. 1 to 5 show a first embodiment of a zoom lens barrel according to the present invention using the optical system of FIG. The fixed cylinder 11 is provided at its rear end with a mount 12 for connection to a camera body. A zoom ring 14 is rotatably fitted on the outer periphery of the fixed cylinder 11. The zoom ring 14 has an end face cam 15 in a step formed on the inner periphery of the intermediate portion, and a large diameter portion 14a is provided in front of the end face cam 15.
It has become.

A front lens support tube 16 is fitted between the large diameter portion 14a and the fixed tube 11 so as to be able to move straight in the optical axis direction. That is, a key groove 18 in a direction parallel to the optical axis is formed on the outer periphery of the fixed cylinder 11, and a key projection 19 that fits into the key groove 18 is provided on the front lens support cylinder 16. On the inner circumference of the distal end of the front lens support cylinder 16,
A female helicoid 21 is formed, and a male helicoid 23 of a focus ring 22 is screwed to the female helicoid 21. The focus ring 22 includes an inner cylinder 22a and an outer cylinder 22b.
The front cylinder lens L1 is supported by the inner cylinder 22a, and the male helicoid 23 is formed. The outer cylinder 22b extends to the outer periphery of the zoom ring 14.

A spring seat ring 24 is engaged with the inner periphery of the distal end of the zoom ring 14, and a compression spring 25 is inserted between the spring seat ring 24 and the end surface of the front lens support cylinder 16. I have. The compression spring 25 pushes the front lens support barrel 16 rearward so that the engagement protrusion 28 on the rear end face always abuts on the end face cam 15 of the zoom ring 14 and the zoom ring 1
4 contacts the outer flange 11 a of the fixed cylinder 11. FIG. 4 shows the deployed shape of the end cam 15 and the engagement relationship between the engagement protrusions 28. Therefore, the zoom ring 14
When the is rotated, the focus ring 22, that is, the front lens group L1 moves by the distance α in the optical axis direction according to the relationship between the end face cam 15 and the engagement protrusion 28. The focus ring 22
Is rotated, the female helicoid 21 and the male helicoid 23
, The front lens L1 moves in the optical axis direction while rotating.

A rear group lens L
The rear group lens frame (rotating cylinder) 33 supporting the lens 2 is fitted so as to rotate and move in the optical axis direction. This rear group lens frame 3
The rear end face 34 engages with an end face cam 35 formed on the inner flange 11b at the rear end of the fixed cylinder 11. Compression spring 3
The spring ring 6 and the spring seat 37 push the rear lens group frame 33 rearward so that the engagement protrusion 34 on the rear end face and the end face cam 35 are always in contact. FIG. 5 shows an expanded state of the end face cam 35 and an engagement state between the engagement projection 34 and the engagement cam 34. A radial interlocking pin 38 is implanted in the rear lens frame 33. The interlocking pin 38 passes through the escape window 39 of the fixed barrel 11 in a direction parallel to the optical axis formed on the zoom ring 14. In the rotation interlocking groove 40.

Therefore, according to the zoom lens barrel having the above-described configuration, by rotating the zoom ring 14, the front lens group L1 and the rear lens group L2 according to the cam surface shapes of the end cams 15 and 35. Can be moved in a predetermined relationship in the optical axis direction to perform zooming. At any focal length, by rotating the focus ring 22, the front lens L1 can be moved in the optical axis direction to perform focusing. The end cams 15 and 35 are different from the cam grooves, and can be formed at low cost because both can be formed by resin molding.

FIGS. 6 and 7 show a second embodiment of the present invention. In the first embodiment, the rear lens L
In this embodiment, the rear lens group L2 moves straight. In this embodiment, the rear group lens frame 33A supporting the rear group lens L2 and the fixed barrel 11A
3 is provided between the rear group lens frame 33A and the outer flange 11a of the fixed barrel 11, and a rotation member formed of a member separate from the rear group lens frame 33A. A moving cylinder 45 is provided. The engaging projection 46 on the rear end face of the rotating cylinder 45 contacts the end face cam 35 of the outer flange 11a, and the same interlocking pin 38 as in the first embodiment is implanted in the rotating cylinder 45. The interlocking pin 38 is fitted in the rotation interlocking groove 40 of the zoom ring 14. Other parts are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals.

According to this embodiment, the rear lens group L2 does not rotate during zooming. Other points are the same as those of the first embodiment.

[0015]

As described above, according to the present invention, a zoom lens barrel can be formed with a simple configuration, and a more inexpensive zoom lens can be provided.

[Brief description of the drawings]

FIG. 1 is an upper half sectional view showing a first embodiment of a zoom lens barrel according to the present invention.

FIG. 2 is an upper half sectional view different from FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a development view of an end face cam of the zoom ring and an end face of a front lens support cylinder.

FIG. 5 is a development view of an end cam of a fixed barrel and an end face of a rotating barrel.

FIG. 6 is an upper half sectional view showing a second embodiment of the zoom lens barrel according to the present invention;

FIG. 7 is an upper half sectional view different from FIG. 6;

FIG. 8 is a lens configuration diagram showing a zoom optical system used in a zoom lens barrel according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 11A Fixed cylinder 12 Coupling mount 14 Zoom ring 15 End cam 16 Front group lens support cylinder 28 34 46 Engagement projection 33 Rear group lens frame (rotating cylinder) 33A Rear group lens frame 35 End face cam 45 Rotating cylinder L1 Front group Lens L2 Rear group lens

Continuing on the front page (72) Inventor Tokio Kataoka 2-5-2 Higashi-Oizumi, Nerima-ku, Tokyo Asahi Precision Co., Ltd. (72) Masaaki Wada 2-5-2 Higashi-Oizumi, Nerima-ku, Tokyo Asahi Precision (72) Inventor Takao Shishido 2-5-2-2 Higashi-Oizumi, Nerima-ku, Tokyo Asahi Seimitsu Co., Ltd. (72) Inventor Tsugio Kanai 2-5-2, Higashi-Oizumi, Nerima-ku, Tokyo Asahi Precision Co., Ltd. (56) References JP-A-1-280707 (JP, A) JP-A-2-103512 (JP, A) JP-A-1-156710 (JP, A) JP-A 64-11212 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 7/04 G02B 7/10

Claims (2)

(57) [Scope of request for utility model registration] 1. A zoom lens barrel having two front and rear lens groups, comprising: a fixed barrel having a mount mounted to a camera body at a rear end; and a straight line extending in the optical axis direction directly on an outer peripheral surface of the fixed barrel. Can move forward and backward
A fitted front-group lens support cylinder; a focus ring supporting the front-group lens and screwed to the front-group lens support cylinder ; directly rotatably fitted to the outer peripheral surface of the front-group lens support cylinder
A zoom ring that rotates all together ; an end surface of the front lens support barrel, and an intermediate portion of the zoom ring.
An end surface cam mechanism for the front group formed between the front lens unit and the peripheral step ; supporting the rear group lens and rotating integrally with the zoom ring;
A rotating cylinder directly fitted to the inner peripheral surface of the fixed cylinder ; after being formed between an end surface of the rotating cylinder and a part of the fixed cylinder.
An end cam mechanism for the group, and the end cam mechanism for the front group and the end cam mechanism for the rear group move the front and rear two lens groups in the optical axis direction in a predetermined relationship according to the rotation of the zoom ring. A zoom lens barrel characterized in that: 2. A zoom lens having two front and rear lens groups.
Fixed barrel with a mounting mount to the camera body at the rear end of the lens barrel
And; can move straight back and forth in the optical axis direction directly on the outer peripheral surface of this fixed cylinder.
A fitted front-group lens support cylinder; supported by the front-group lens and screwed into the front-group lens support cylinder
A focus ring; rotatably fitted directly to the outer peripheral surface of the front lens support cylinder
A zoom ring that rotates all together; an end surface of the front lens support barrel, and an intermediate portion of the zoom ring.
An end surface cam mechanism for the front group formed between the peripheral section and the rear group lens ; and supporting the rear group lens on the inner peripheral surface of the fixed cylinder in the optical axis direction.
A rear lens group frame which is directly fitted so as to be able to rectilinearly advance and retreat; and an inner peripheral surface of the fixed cylinder which rotates integrally with the zoom ring.
A rotating cylinder directly fitted ; an end face of the rotating cylinder and a part of the fixed cylinder, or an end face of the rotating cylinder
The rear group end face cover formed between the
Arm mechanism and; equipped with, the front end cam for the rear group and the end face cam group of the zoom ring times
According to the rotation, the front and rear two lens groups are moved in the optical axis direction in a predetermined relationship.
A zoom lens barrel characterized by being moved to