JPH0573615U - Zoom lens barrel - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a zoom lens barrel that can be provided at a low cost with a simple structure. [Structure] A zoom lens barrel using front and rear two lens units, wherein a front barrel lens support is provided on a fixed barrel equipped with a mount for coupling to a camera body at a rear end thereof so that the front lens group can be moved forward and backward in the optical axis direction. The lens barrel is supported, the focus ring supporting the front lens group is screwed onto the front lens group support barrel, and the zoom ring is rotatably supported on the fixed barrel. The end surface of the zoom ring and the front lens group support are supported. An end face cam is formed between the end face of the tube and the zoom ring so that the front group lens moves in the optical axis direction, while the rear group lens rotates together with the zoom ring. A zoom lens barrel that moves in the optical axis direction by a moving barrel and a rear group lens moving means that moves the rear group lens in the optical axis direction as the rotary barrel rotates.

Description

[Detailed description of the device]

[0001]

【Technical field】

 The present invention relates to a zoom lens barrel.

[0002]

[Prior art and its problems]

 Various structures are known for the zoom lens barrel, but these basically form a cam groove in the cam ring that determines the movement trajectory of the moving lens group. However, precision machining of cam grooves is expensive. For this reason, it was generally accepted that zoom lens barrels are expensive.

[0003]

[The purpose of the device]

 An object of the present invention is to obtain a zoom lens barrel which can be provided at a low cost with a simple structure.

[0004]

[Outline of the device]

 The present invention uses two lens groups, front and rear, and a front barrel lens support barrel is supported on a fixed barrel equipped with a mount for connecting to the camera body at the rear end so that it can move forward and backward in the optical axis direction. Then, the focus ring supporting the front lens group is screwed into this front lens group support barrel, and the zoom ring is rotatably supported on the fixed barrel. The end surface of this zoom ring and the end surface of the front lens group support barrel An end surface cam is formed between the rear lens group and the front ring lens so that the front lens group moves in the optical axis direction when the zoom ring rotates, while the rear lens group rotates together with the zoom ring. And the rear group lens moving means for moving the rear group lens in the optical axis direction in accordance with the rotation of the rotating barrel.

The rear lens group moving means may be configured, for example, by supporting the rear lens group on the rotating barrel itself, and similarly providing an end face cam between the end face of the rotating barrel and the end face of the fixed barrel. it can .

The rear lens group moving means makes contact with the rear lens group, which supports the rear lens group and which is supported by the fixed barrel so as to be able to move forward and backward in the direction of the optical axis, and the rear lens frame with its end faces contacting each other. It can be composed of a rotating barrel and an end face cam formed between the end face of the rotating barrel and the end face of the fixed barrel or between the end face of the rotating barrel and the end face of the rear lens frame.

[0007]

[Example of device]

 The present invention will be described below with reference to 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 is composed of two groups, a front lens group L 1 and a rear lens group L 2. (A) shows the shortest focal length (for example, 38 mm). From this state, if the front lens group L1 and the rear lens group L2 are moved in the forward direction by changing the distance between them in a predetermined relationship, the focal length becomes It changes to the intermediate focal length (50 mm) (B) and the longest focal length (60 mm) (C). Focusing is performed by adjusting the position of the front lens unit L1 in the optical axis direction at any focal length.

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

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

A spring seat ring 24 is locked on the inner circumference of the front end portion 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 group support barrel 16. Has been. The compression spring 25 pushes the front lens group support cylinder 16 rearward so that the engagement projection 28 on the rear end surface of the compression spring 25 is always brought into contact with the end cam 15 of the zoom ring 14, and the zoom ring 14 is attached to the outer flange of the fixed cylinder 11. It is to be brought into contact with 11a. FIG. 4 shows a developed shape of the end surface cam 15 and an engagement relationship of the engagement protrusions 28. Therefore, when the zoom ring 14 is rotated, the focus ring 22, that is, the front group lens L1 moves by the distance α in the optical axis direction in accordance with the relationship between the end surface cam 15 and the engaging projection 28. When the focus ring 22 is rotated, the front lens group L1 moves in the optical axis direction while rotating in accordance with the female helicoid 21 and the male helicoid 23.

A rear lens group frame (rotating cylinder) 33, which supports the rear lens group L2, is fitted on the inner periphery of the rear portion of the fixed barrel 11 so as to be rotatable and movable in the optical axis direction. The rear end surface 34 of the rear group lens frame 33 engages with the end surface cam 35 formed on the inner flange 11b at the rear end of the fixed barrel 11. The compression spring 36 and the spring seat ring 37 push the rear lens group frame 33 rearward so that the engagement projection 34 on the rear end face and the end face cam 35 are always in contact with each other. FIG. 5 shows the developed shape of the end surface cam 35 and the engagement state with the engagement protrusion 34. A radial interlocking pin 38 is planted in the rear lens group frame 33. The interlocking pin 38 passes through the escape window 39 of the fixed barrel 11 and is aligned with the optical axis formed on the zoom ring 14. It fits in the rotation interlocking groove 40 in various directions.

Therefore, according to the present zoom lens barrel having the above-described configuration, by rotating the zoom ring 14, the front lens group L1 and the rear lens group L1 follow the cam surface shapes of the end cams 15 and 35. Zooming can be performed by moving L2 in the optical axis direction in a predetermined relationship. Then, by rotating the focus ring 22 at any focal length, the front lens group L1 can be moved in the optical axis direction for focusing. Further, unlike the cam groove, the end cams 15 and 35 can be resin-molded and can be manufactured at low cost.

6 and 7 show a second embodiment of the present invention. In the first embodiment, the rear lens group L2 is rotated in association with zooming, but in this embodiment, the rear lens group L2 is moved straight. In this embodiment, a rectilinear guide mechanism 44 similar to that shown in FIG. 3 is provided between the rear lens group frame 33A supporting the rear lens group L2 and the fixed barrel 11A, while the rear lens group frame 33A and the fixed barrel 11 are connected to each other. A rotating cylinder 45, which is a member separate from the rear lens frame 33A, is provided between the outer flange 11a and the outer flange 11a. The engaging projection 46 on the rear end surface of the rotary cylinder 45 contacts the end surface cam 35 of the outer flange 11a, and the same interlocking pin 38 as that of the first embodiment is implanted in the rotary cylinder 45. The interlocking pin 38 is fitted in the rotation interlocking groove 40 of the zoom ring 14. The other parts are the same as those in the first embodiment, and the same parts are designated by the same reference numerals.

According to this embodiment, the rear lens group L2 does not rotate during zooming. The other points are the same as in the first embodiment.

[0015]

[Effect of the device]

 As described above, according to the present invention, a zoom lens barrel can be constructed with a simple structure, and a cheaper zoom lens can be provided.

[Brief description of 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 in a state different from that in FIG.

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

FIG. 4 is a development view of an end surface cam of a zoom ring and an end surface of a front lens group supporting cylinder.

FIG. 5 is a development view of an end face 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 in a state different from FIG.

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]

 11 11A Fixed barrel 12 Combined mount 14 Zoom ring 15 End face cam 16 Front group lens support barrel 28 34 46 Engagement protrusion 33 Rear group lens frame (rotating barrel) 33A Rear group lens frame 35 End face cam 45 Rotating barrel L1 Front group Lens L2 Rear group lens

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Tokio Kataoka 2-5-2 Higashi Oizumi, Nerima-ku, Tokyo Within Asahi Seiko Co., Ltd. (72) Masaaki Wada 2-5-2 Higashi-oizumi, Nerima-ku, Tokyo No. 2 Asahi Seiko Co., Ltd. (72) Inventor Takaho Shishido 2-5-2 Higashi-Oizumi, Nerima-ku, Tokyo No. 2 2 Asahi Seiko Co., Ltd. (72) Tsuguo Kanai 2-chome, Higashi-oizumi, Nerima-ku, Tokyo No. 2 Asahi Seiko Co., Ltd.

Claims (3)

[Scope of utility model registration request] 1. A zoom lens barrel having two front and rear lens groups, a fixed barrel having a mount for coupling to a camera body at a rear end thereof; and a straight barrel which can be moved back and forth in the optical axis direction on the fixed barrel. A front group lens support tube that supports; a focus ring that supports the front group lens and is screwed into the front group lens support tube; a zoom ring that is rotatably supported by the fixed cylinder; and an end surface of the zoom ring. An end face cam formed between the front lens group support barrel and an end surface of the front lens group support barrel; a rotary barrel that rotates integrally with the zoom ring; and a rear lens group in the optical axis direction as the rotary barrel rotates. And a rear lens group moving means for moving the front lens group and the rear lens group moving means to move the front and rear lens groups in the optical axis direction in a predetermined relationship according to the rotation of the zoom ring. And zoom lens barrel. 2. The rear group lens moving means according to claim 1, wherein the rear group lens is supported by the rotating barrel itself; and an end face cam formed between the end face of the rotating barrel and the end face of the fixed barrel. When;
A zoom lens barrel composed of. 3. The rear lens group moving means according to claim 1, wherein the rear lens group moving means supports a rear lens group, and a fixed lens barrel supports the rear lens group so as to be able to move forward and backward in the optical axis direction; And the end face cam formed between the end face of the turn barrel and the end face of the fixed barrel or between the end face of the turn barrel and the end face of the rear lens group frame. A zoom lens barrel.