JPH06194556A - Movable lens guiding mechanism for zoom lens-barrel - Google Patents

Abstract

PURPOSE:To provide the movable lens guiding mechanism of simple structure using a cam ring whose structure is simplified and resinification is facilitated. CONSTITUTION:The movable lens guiding mechanism is provided with an inside fixed ring 13 having a rectilinear guiding groove 14 in parallel with the optical axis of a photographic optical system, the cam ring 20 freely rotatably fitted into the outer periphery of the inner fixed ring 13 and a rectilinear guiding part 19 moved/guided to the rectilinear guiding groove 14 of the inside fixed ring, a rear group lens frame 17 supporting a rear group lens constituting the photographic optical system and fitted into the inside periphery of the inner fixed ring 13 and helicoids 21 and 22 provided on the outer periphery of the rectilinear guiding part 19 of the rear group lens frame 17 and the inner periphery of the cam ring 20, respectively and engaged each other.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a movable lens guide mechanism for a zoom lens barrel.

[0002]

2. Description of the Related Art Generally, in a zoom lens barrel of a camera, the focal length is changed by moving at least two movable lens groups in the front and rear along a predetermined locus in the optical axis direction. The movable lens group is normally guided straight ahead, and the movable lens group guided straight forward is given a non-linear movement by a cam groove. In such a structure of the conventional zooming mechanism, since the cam ring has a plurality of complicated cam grooves, it is difficult to process the resin, and the metal cam ring is formed by machining.

[0003]

An object of the present invention is to simplify the structure of the cam ring and facilitate its resinification. Another object of the present invention is to provide a movable lens guide mechanism using the cam ring and having a simple structure.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a rotatably provided annular member, a movable lens frame which supports a lens group constituting a photographing optical system, and is movable in the optical axis direction; A curved portion provided on one of the lens frame side and the annular member side; and a sandwiching portion provided on the other of the movable lens frame side and the annular member side and sandwiching the curved portion so as to be relatively movable. It is characterized by that.

Further, according to the present invention, a first annular member having a linear guide groove in a direction parallel to the optical axis of the photographing optical system; a second annular member rotatably fitted to the outer periphery of the first annular member; A movable lens frame fitted to the inner circumference of the first annular member, which has a linear guide portion that is guided to move in the linear guide groove of the annular member, and supports a lens group that constitutes the above-mentioned photographing optical system; The movable lens frame is provided with helicoids which are provided on the outer peripheral surface of the straight-ahead guide portion and the inner peripheral surface of the second annular member, and which mesh with each other.

Further, according to the present invention, a fixed ring having a straight guide groove in a direction parallel to the optical axis of the photographing optical system; a cam ring rotatably fitted on the outer periphery of the fixed ring; a lens group constituting the photographing optical system. A first movable lens frame that supports the optical axis direction and that is movable between the first movable lens frame and a cam ring, and that moves the first movable lens frame when the cam ring rotates. A second movable lens frame fitted to the inner periphery of the fixed ring, the second movable lens frame having a straight guide portion fitted in the straight guide groove of the fixed ring; and a straight guide portion of the second movable lens frame, and the cam. It is characterized in that helicoids provided on the inner peripheral surface of the ring and meshing with each other are provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. First, a first embodiment in which the present invention is applied to an interchangeable zoom lens barrel of a single-lens reflex camera will be described with reference to FIGS. The zoom lens barrel 10 shown in FIG. 1 has an outer fixed ring 12 and an inner fixed ring 13 which is a linear guide tube fixed to a detachable mount 11. The outer fixed ring 12 and the inner fixed ring 13 are fixed to the camera body (that is, relative movement with respect to the camera body) when the zoom lens barrel 10 is mounted on the camera body (not shown).
In addition, 9 in the figure is a fixing screw for fixing the inner fixed ring 13 to the outer fixed ring 12.

Reference numeral O in FIG. 1 denotes an optical axis of a photographing optical system (not shown) of the zoom lens barrel 10. The inner fixed ring 13 has a linear guide groove 14 formed so as to be parallel to the optical axis O. The rear lens group frame 17 is located on the inner circumference of the inner fixed ring 13 and holds the rear lens group L2, and integrally has a straight guide portion 19 that projects outward in the radial direction. 19 is fitted in the straight guide groove 14.

A cam ring 20 is provided on the outer circumference of the inner fixed ring 13.
It is fitted so that it can rotate relative to the inner fixed ring 13 and cannot move in the optical axis direction. As shown in FIG. 5, the cam ring 20 has a pair of guide rollers 15 and 18 provided on the outer periphery of the front part thereof at a predetermined interval in the front-rear direction of the optical axis. The front group moving ring 2 is provided on the outer circumference of the front part of the cam ring 20.
4 is fitted so as to be relatively rotatable. This front group moving ring 24
Has a curved projection 25 formed by bending in a curved or arcuate shape and protruding inward in the radial direction. The curved protrusion 25 is formed so as to bend back from the front side (left side in FIG. 5) of the optical axis of the zoom lens barrel 10 to the rear side (right side).
The thickness is set so that the front group moving ring 24 is fitted into the cam ring 20 so as to fit between the two guide rollers 15 and 18 without a gap. Therefore, the cam ring 2
When 0 is rotated relative to the inner fixed ring 13, the guide roller 1 moves vertically with the cam ring 20 in FIG.
Since 5 and 18 roll along the arcuate shape of the curved projection 25, the front group moving ring 24 relatively moves in the front-rear direction of the optical axis with respect to the cam ring 20 whose movement in the optical axis direction is restricted.

Further, as shown in FIGS. 1 and 4, the rear lens group frame 17 has three male helicoids 21 on the outer peripheral surface 19a of the rectilinear guide portion 19. The length (width) along the circumferential direction of the rear group lens frame 17 of the straight-movement guide portion 19 is formed to be substantially the same as the width of the straight-movement guide groove 14 in the circumferential direction of the cam ring 20. It is set so as not to rattle when it is fitted in the straight guide groove 14 and to be freely movable in the front-back direction of the optical axis.

As shown in FIGS. 1 to 3, a female helicoid 22 that meshes with a male helicoid 21 formed in the rectilinear guide portion 19 of the rear lens group frame 17 is formed on the inner peripheral surface of the cam ring 20. The female helicoid 22 is formed with three threads so that it can mesh with the three male helicoids 21. The male helicoid 21 of the linear guide section 19 is provided with a linear guide groove 14 when the rear lens group frame 17 is assembled in a normal state.
Can be properly engaged with the female helicoid 22 of the cam ring 20.

A focusing ring 26, which can be rotated from the outside, is screwed onto the outer circumference of the front group moving ring 24 by a screw 27, and the front group lens frame 16 described above holds a pressing ring 28 on the focusing ring 26. Is fixed through.
At the front end portion of the inner fixed ring 13, a support protrusion 13a is formed that protrudes radially outward so as to slidably support the inner peripheral surface of the front group moving ring 24 in the optical axis direction.

A zoom ring 30, which can be rotated from the outside, is rotatably fitted on the outer periphery of the outer fixed ring 12. The zoom ring 30 and the cam ring 20 are connected by a connecting pin 31 penetrating the circumferential elongated hole 32 of the outer fixed ring 12, and therefore the cam ring 20 is connected to the zoom ring 3 by the zoom ring 3.
It is possible to make a rotation that is always equal to zero.

The present zoom lens barrel 1 having the above configuration
0 can be activated as follows. First, when the zoom ring 30 is operated and rotated, the cam ring 20
It rotates integrally with the zoom ring 30 via the connecting pin 31. Then, due to the relationship between the male helicoids 21 and 22,
The rear group lens frame 17 (rear group lens L2) moves its straight guide portion 19 along the straight guide groove 14 and moves in the front-back direction of the optical axis. At the same time, the guide rollers 15 and 18 that move in the rotational direction of the cam ring 20 roll along the arcuate surfaces of the curved projection 25, respectively.
A moving force in the front-back direction of the optical axis is given to 4. Therefore, the focusing ring 26 moves in the same direction as the front group moving ring 24, and the front group lens L1 and the rear group lens L2 are moved in the optical axis direction in a predetermined relationship to perform zooming.

Further, when the focusing ring 26 is manually rotated, the front lens group frame 16 (front lens group L1) is moved in the optical axis direction in accordance with the screw 27 formed on the inner circumference of the ring to perform focusing. .

As described above, according to the movable lens guiding mechanism of the present embodiment, it is possible to form a part of the driving mechanism of the front lens group L1 only by providing the guide rollers 15 and 18 on the cam ring 20, and the cam can be constructed. A female helicoid 22 is formed on the inner peripheral surface of the ring 20.
It is possible to form a part of the drive mechanism of the rear lens group L2 by simply forming Therefore, unlike a conventional cam ring having a plurality of complicatedly shaped cam grooves, its structure is greatly simplified, and thus resin processing such as injection molding can be easily realized. As a result, the accuracy of the cam ring 20 can be easily improved, and the front lens group L1
Therefore, it is possible to eliminate backlash when guiding the rear lens group L2. Therefore, it becomes possible to smooth the zooming operation and improve the optical performance of the zoom lens barrel 10.

In the second embodiment shown in FIGS. 6 to 8, the present invention is applied to the zoom lens barrel 10 of a single-lens reflex camera as in the case of the first embodiment.
9. There are differences in the structures of the male helicoid 21 on the outer peripheral surface and the female helicoid 22 on the inner peripheral surface of the cam ring 20. That is, the male helicoids 21 and 2 formed as the three threads in the first embodiment
No. 2 is one in the second embodiment. According to this configuration, the three-line male helicoids 21 and 22 of the first embodiment described above are used.
It is possible to obtain the same effect as the above, and when molding the straight guide portion 19 by injection molding or the like, it is sufficient if the parting line formed by the mold is along one male helicoid 21. It can be done easily and can be easily die-cut. In addition, the female helicoid 22 on the inner circumference of the cam ring 20 can also be a single line in correspondence with this,
Even when the cam ring 20 is molded with a mold, the mold can be easily removed.

In the first and second embodiments, only one straight guide groove 14 is provided in the inner fixed ring 13 in parallel with the optical axis O, and the corresponding straight guide portion 19 is provided correspondingly to the rear group lens frame 17. Only one can be provided in the circumferential direction. In that case, in the first embodiment, as shown in FIG. 3, the female helicoid 22 on the inner peripheral surface of the cam ring 20 corresponds to one set of male helicoids 21 by the three lines of one straight guide portion 19 only. It may be formed. Further, in the second embodiment, FIG.
As described above, the female helicoid 22 on the inner peripheral surface of the cam ring 20 is provided with a single male helicoid 21 having one straight guide portion 19.
It is sufficient to form only one line corresponding to.

Further, in the first and second embodiments, a pair of rectilinear guide grooves 14 are provided at rotationally symmetrical positions about the optical axis O of the inner fixed ring 13, and the rectilinear guide part 19 is provided correspondingly. Two pieces (a pair) can be provided in the circumferential direction of the group lens frame 17. In that case, in the first embodiment, the cam ring 2
0 The female helicoid 22 on the inner peripheral surface is attached to the pair of straight guide portions 1
One set of three male helicoids 9 each has
Corresponding to No. 1, one set of three sets may be formed. Further, in the second embodiment, the female helicoids 22 on the inner peripheral surface of the cam ring 20 may be made to correspond to the male helicoids 21 of the pair of straight-moving guide portions 19, respectively, so that a pair of the female helicoids 21 may be formed.

Further, a plurality of straight guide grooves 14 are provided in the inner fixed ring 13 in a number exceeding one pair, and the straight guide portions 19 are provided in the rear lens group frame 17.
The same applies to the case of providing more than one pair. In that case, the female helicoids 22 on the inner peripheral surface of the cam ring 20 are made to correspond to the male helicoids 21 (or 3 lines) each of which has a pair of straight guides 19 and the pair of 1 (or 3) lines are formed. It suffices to form only a number exceeding.

The male helicoid 21 and the female helicoid 2
2 does not have to be formed as the three-row or one-row as shown in the first and second embodiments, and may be formed as the number of the threads exceeding three or as the two-row.

In the first embodiment, the pair of guide rollers 15 and 18 are provided on the cam ring 20 and the curved projection 25 is provided on the front group moving ring 24. However, the relationship between the two may be reversed. That is, the same operation can be performed even if the curved projection 25 is provided on the cam ring 20 side and the pair of guide rollers 15 and 18 is provided on the front group moving ring 24 side.

Further, in the first and second embodiments, the present invention is applied to the interchangeable zoom lens barrel 10. However, the present invention is not limited to the interchangeable type, but the zoom optical system is moved in the optical axis direction by the rotation of the cam ring. It can be applied to all zoom lens barrels whose position is changed by. Further, in the first and second embodiments, the present invention is applied to the zoom lens barrel 10 of a single-lens reflex camera, but the present invention is not limited to a camera including a zoom lens.
The present invention can be applied to any type of camera such as a lens shutter type camera and an electronic still camera.

[0024]

As described above, according to the present invention, a part of the lens driving mechanism can be formed only by providing a curved portion or a sandwiching portion in the annular member, and thus the structure of the annular member is simplified. Thus, resin processing such as injection molding can be easily realized. This makes it possible to easily improve the accuracy of the annular member, for example, the cam ring, and to eliminate play when guiding the movable lens frame as much as possible. Therefore, it becomes possible to smooth the zooming operation and improve the optical performance of the zoom lens barrel.

According to the fourth aspect of the present invention, a part of the lens driving mechanism can be formed only by providing the second annular member with a helicoid, and thus the structure of the second annular member can be simplified and the injection can be performed. Resin processing such as molding can be easily realized. As a result, it is possible to easily improve the accuracy of the second annular member, for example, the cam ring, and it is possible to eliminate backlash when guiding the movable lens frame. Therefore, it becomes possible to smooth the zooming operation and improve the optical performance of the zoom lens barrel.

According to the invention of claim 6, in the cam ring,
A part of the zooming mechanism can be configured only by providing a simple shape helicoid and a part of the movement guide means,
Therefore, it is possible to simplify the structure of the cam ring and easily realize resin processing such as injection molding. As a result, the accuracy of the cam ring can be easily improved, and it is possible to eliminate rattling when guiding the first and second movable lens frames. Therefore, it becomes possible to smooth the zooming operation and improve the optical performance of the zoom lens barrel.

[Brief description of drawings]

FIG. 1 is an upper half sectional view showing an embodiment of a zoom lens barrel to which the present invention has been applied.

FIG. 2 is a view showing a female helicoid formed on an inner peripheral surface of a cam ring.

FIG. 3 is a partially cutaway vertical sectional view showing a female helicoid of the cam ring.

FIG. 4 is a perspective view showing a state in which a rectilinear guide portion of a rear lens group frame is fitted in a rectilinear guide groove of an inner fixed ring.

FIG. 5 is a plan view showing an engagement state between a curved protrusion and a guide roller provided at a front end portion of a cam ring.

FIG. 6 is a view showing a female helicoid on the inner peripheral surface of the cam ring in the second embodiment.

FIG. 7 is a partially cutaway vertical sectional view showing a female helicoid of the same cam ring.

FIG. 8 is a perspective view showing a state in which a rectilinear guide portion of a rear lens group frame is fitted into a rectilinear guide groove of an inner fixed ring in the second embodiment.

[Explanation of symbols]

10 zoom lens barrel 12 outer fixed ring 13 inner fixed ring (fixed ring, first annular member) 13a support protrusion 14 straight guide groove 16 front lens group frame (movable lens frame, first movable lens frame) 15 18 guide roller ( 17) Rear group lens frame (movable lens frame, second movable lens frame) 19 Straight guide portion 20 Cam ring (annular member, second annular member) 21 Male helicoid (moving guide means) 22 Female helicoid (moving guide) Means) 24 front group moving ring 25 curved projection (curved portion) 26 focusing ring 30 zoom ring 31 coupling pin L1 front group lens (lens group) L2 rear group lens (lens group) O optical axis

Claims (7)

[Claims] 1. A rotatably provided annular member; a movable lens frame that supports a lens group that constitutes a photographing optical system and is movable in the optical axis direction; provided on one of the movable lens frame side and the annular member side. A zoom lens barrel including: a curved portion; and a sandwiching portion that is provided on the other side of the movable lens frame side and the annular member side and sandwiches the curved portion so as to be relatively movable. Movable lens guide mechanism. 2. The movable lens guide mechanism for a zoom lens barrel according to claim 1, wherein the annular member is a cam ring, and the movable lens frame is a front lens group supporting the front lens group. 3. The curved portion according to claim 2, wherein the curved portion is a curved protrusion formed in an arc shape or a curved shape and connected to the front lens group frame, and the sandwiching portion is provided on the outer circumference of the cam ring. , A movable lens guide mechanism for a zoom lens barrel, which is a pair of guide rollers provided at a predetermined interval in the optical axis direction. 4. A first annular member having a straight guide groove in a direction parallel to the optical axis of the photographing optical system; a second annular member rotatably fitted to the outer periphery of the first annular member; A movable lens frame fitted to the inner periphery of the first annular member, which has a linear guide portion that is guided to move in the linear guide groove, and which supports a lens group that constitutes the above-mentioned photographing optical system; and this movable lens frame. 2. A movable lens guide mechanism for a zoom lens barrel, comprising: helicoids, which are provided on the outer peripheral surface of the straight guide portion and the inner peripheral surface of the second annular member, and which mesh with each other. 5. The zoom lens mirror according to claim 4, wherein the first annular member is an inner fixed ring, the second annular member is a cam ring, and the movable lens frame is a rear group lens frame that supports the rear group lens. Cylinder movable lens guide mechanism. 6. A fixed ring having a straight guide groove in a direction parallel to the optical axis of the photographing optical system; a cam ring rotatably fitted to the outer periphery of the fixed ring; and a lens group constituting the photographing optical system. A first movable lens frame movable in the optical axis direction; a movement guide means provided between the first movable lens frame and the cam ring, and moving the first movable lens frame when the cam ring rotates;
A straight guide portion that fits in the straight guide groove of the fixed ring,
A second movable lens frame fitted to the inner circumference of the fixed ring; and
A movable lens guide mechanism for a zoom lens barrel, comprising: a straight guide portion of the second movable lens frame and interlocking helicoids respectively provided on the inner peripheral surface of the cam ring. 7. The zoom lens mirror according to claim 6, wherein the first movable lens frame is a front lens group supporting the front lens group, and the second movable lens frame is a rear lens group supporting the rear lens group. Cylinder movable lens guide mechanism.