JPS5922921B2 - zoom lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens barrel of a zoom lens, in particular, at least two lens barrels.
The present invention relates to a zoom lens barrel having a group of movable lens systems.

A zoom lens system is usually composed of three lens groups, and for focusing, the relative distance of the first group lens system to the second and third lens groups is changed, and for zoom operation, all groups are This is done by changing the relative spacing of

Furthermore, although the second and third lens groups should originally be integrated, the distance between them is adjusted for correction by the zoom operation. Therefore, when adjusting the distance between the second and third lens groups, it is required to minimize eccentricity as compared to other lens systems. To meet this requirement, conventionally, lens support frames as shown in FIGS. 1 and 2 have been used.

That is, in the example of FIG. 1, the support frame 2 of the second group lens system consisting of lenses Li and L2 and the support frame 3 of the third group lens system consisting of lens L3 are arranged one behind the other in the fixed frame 1. and are movably fitted together. When placed like this,
It becomes necessary to reduce the width of the lens support frame by the movement range of each lens support frame 2, 3, and since the support frame width cannot be increased by that much, the fitting sliding surface is reduced and eccentricity occurs. It has the disadvantage that it is easy to use, and the overall length of the lens barrel is long. In addition, in order to increase the fitting sliding surface of the lens support frame, an inner cylinder 5 is installed in the fixed frame 4 as shown in the example in FIG.
are integrally formed, and the support frame 6 of the second group lens system is inserted between the inner tube 5 and the fixed frame 4, and the fitting slide of the support frame 6 and T of the second and third group lens systems is formed integrally. There are models with a larger moving surface, but if you do this, the structure will be complicated by the inner cylinder 5, and the outer diameter of the fixed frame 4 will have to be increased, causing eccentricity. This also increases the size of the lens barrel, which increases cost. In view of the above points, an object of the present invention is to fit a support frame for one movable lens system into the fixed frame, and to movably fit the other movable lens system support frame into this support frame. The object of the present invention is to provide a lens barrel for a zoom lens in which the above-mentioned conventional drawbacks are eliminated by arranging the above-mentioned lens support frames so as to overlap each other.

With this configuration, the fitting sliding surfaces of the support frames of the movable lens systems of the second and third groups, that is, the fitting length, can be made sufficiently large, and eccentricity and inclination can be minimized. However, the structure is simple and the overall shape does not increase in size, which provides extremely great effects. The present invention will be explained below based on an embodiment shown in FIGS. 3 to 9.

FIG. 3 is a sectional view of a zoom lens barrel consisting of three lens groups.

The lens barrel u includes a fixed frame 12 whose main part is in the shape of a double cylinder;
The support frame 14 of the third group movable lens Ll4 is slidably fitted into the inner circumferential surface of the inner cylinder 12a of the fixed frame 12, and the second lens group Ll4 is slidably fitted into the inner circumferential surface of the support frame 14. A support frame 13 for the group movable lenses L, , Ll, and a first group lens L, which is located between the inner and outer tubes 12a and 12b of the fixed frame 12 and slidably fits on the outer peripheral surface of the inner tube 12a. l support frame 15;
The distance between the lens driving ring 16 that is slidably fitted on the outer peripheral surface of the support frame 15 and the helicoid screw 12c provided on the outside of the outer cylinder 12b of the fixed frame 12 through the helicoid screw 12c. a ring 17, a lens hood attachment member 18 attached to the distance ring 17, a zoom ring 19 rotatably fitted to the outer peripheral surface of the outer cylinder 12b of the fixed frame 12;
This zoom Fi! An interlocking member 20 is integrally attached to the lens support frame 19 and drives each lens support frame 13, 14, 15.
It is made up of. At the rear end of the fixed frame 12 (on the right side in the figure), there is a mount screw 29 for attaching it to the camera body.
is provided so that the lens barrel Aj is fixed to the camera body (not shown). As shown in FIG. 4, the support frame 13 formed of a cylinder that holds the second group of movable lens systems consisting of lenses L, . A partially arcuate cam slot 13a into which a driving roller 23 (see FIG. 3) to be described later fits is provided, and a fixed roller 25 (to be described later) is provided in the lower wall corresponding to the slot 13a. A long hole 13b parallel to the optical axis 01-02 is provided, into which the optical axis 01-02 (see figure) is fitted.

The support frame 14 of the movable lenses L, , of the third lens group, which fits on the outer peripheral surface of the support frame 13, is also formed of a cylindrical body, and as shown in FIG. 5, the left end of its upper wall Nearby,
A partially arcuate cam slot 14a into which a driving roller 22 (see FIG. 3), which will be described later, is fitted is provided, and a fixed roller 26, which will be described later, is provided in the lower wall corresponding to the slot 14a.
(See FIG. 3) is provided with a long hole 14b parallel to the optical axis 01-02 into which the optical axis 01-02 is fitted. The fitted state of the support frame 13 of the second group lens and the support frame 14 of the third group lens is determined by the above-mentioned fittings provided on the upper walls of both frames 13 and 14, respectively, as shown in FIG. The cam slot holes 13a and 14a are orthogonal to each other when viewed from above, and the elongated holes 13b are provided in the lower wall, respectively.
14b has been polymerized to match.

Fits into the inner cylinder 12a of the fixed frame 12, and the first group lens Lll
As shown in FIG. 7, the support frame 15 holding the support frame 15 is formed of a cylindrical body, and a lens driving ring 16, which will be described below, is mounted on the inner peripheral surface of the upper wall at approximately the center of its upper wall. Upright drive pin 16
A fixed roller 27 (see FIG. 3) is provided on the lower wall of the arcuate cam slot 15a into which the cam slot 15a is fitted. A long hole 15b into which is fitted is provided.

As shown in FIG. 8, the lens drive ring 16 that fits on the outer peripheral surface of the support frame 15 is formed of a cylindrical body.
The right edge of the upper wall has a cutout groove 16a in the optical axis direction into which the tip of the upper side 20a of the interlocking member 20 (to be described later) is fitted.
is provided. A driving pin 16b that fits into the cam slot 15a of the support frame 15 is installed on the inner peripheral surface of the upper wall, and a ring-shaped protrusion 16c is integrated near the left end of the outer peripheral surface. is formed. The support frame 15 and lens drive ring 16 of the first lens group Lll are fitted together as shown in FIG. 9. That is, when the lens drive Fitl6 moves back and forth along the optical axis 01-02 by the means described later, the support frame 15 is moved back and forth by the drive pin 16b fitted in the cam slot 15a of the support frame 15. do.

At this time, the support frame 15 rotates through the elongated hole 15b.
Since it is restrained by the fitting of the fixed roller 27, it moves only in the front-back direction along the optical axes 0 and -02. Also, when the lens drive ring 16 rotates, its drive pin 16b
The support frame 1 of the first lens group L, l is also rotated and is prevented from rotating by the elongated hole 15b and the fixed roller 27.
The pin 16b pushes the inner edge of the cam slot 15a of No. 5 to move it in the front-back direction. In this way, even if the lens drive ring 16 moves back and forth or rotates, the support frame 15 is fitted so that it always moves back and forth.
Returning to FIG. 3 again, the distance ring 17 is screwed into the helicoid screw 12c provided at the tip of the outer cylinder 12b of the fixed frame 12 and moves back and forth by rotation, and the range of rotation is adjusted as appropriate. stopper (shown and regulated by force).

A lens hood attachment member 18 is fixed to the front end (left side in the figure) of the distance ring 17 by screwing.

Two stripes formed by a ring-shaped protrusion 17a provided on the inner circumferential surface near the front end of the distance ring 17, the mounting member 18, and the ring-shaped protrusion 16c of the lens drive ring 16 are provided. A bearing ball 28 is fitted into the ring-shaped cavity. The zoom ring 19 is attached to the outer cylinder 12 of the fixed frame 12.
It is rotatably fitted to the outer peripheral surface near the rear end of b.
A part of it has a through hole 12 formed by a circumferential groove perpendicular to the optical axis 0, -02 bored in the outer cylinder 12b of the fixed frame 12.
An interlocking shaft 19a passing through d is fixed. Also,
The rotation range of the zoom ring 19 is such that this shaft 19a is in the circumferential groove 1.
It is regulated by coming into contact with the inner edge of 2d. At the lower end of this interlocking shaft 19a, inner and outer cylinders 12a of the fixed frame,
12b, an upper side 20a of a plate-shaped interlocking member 20 whose longitudinal section is bent into a U-shape is fixed. The lower side 20b of this interlocking member 20 is connected to the fixed frame 1
A support shaft 2 that supports the drive rollers 22 and 23 extends into the notched groove 12e of the inner cylinder 12a of No.
1 is planted facing downward. This support shaft 21 is
Cam slot holes 13a and 14a (fourth and fifth holes) provided in the second group lens support frame 13 and the third group lens support frame 14
drive rollers 23 and 22, which fit into the rollers (see figure), are rotatably supported. Further, the lens support frame 1 of the second group
In the long holes 13b and 14b provided in the lens support frames 14 of the third and third group, respectively, the fixed roller 25 is rotatably supported by a support shaft 24 installed in the inner cylinder 12a of the fixed frame 12. , 26 are fitted together.

Further, on the outer circumferential surface of the inner cylinder 12a of the fixed frame 12, the elongated hole 15b provided in the circumferential wall of the lens support frame 15 of the first group is formed.
A support shaft 27a is installed to rotatably support a fixed roller 27 that fits into the support shaft 27a. Furthermore, an extensible coil spring 30 is fitted between the right end surface of the second group lens support frame 13 and the left end surface of the lens holding portion 14c at the right end of the third group lens support frame 14. , giving the habit of separating both frames 13 and 14. This natural separation is normally regulated by the fact that the respective frames 13 and 14 are fitted with the driving rollers 23 and 22 and the respective cam slots 13a and 14a. This behavior eliminates any play in fitting between the two. The lens barrel u of the present invention constructed as described above operates as follows. First, the first
When focusing by moving the lens Lll of the group back and forth, if the distance ring 17 is rotated around the optical axis 0, -02,
Due to the helicoid screw action with the outer cylinder 12b of the fixed frame 12, the distance ring 17 moves back and forth along the optical axis 0, -0, and the distance ring 17 moves back and forth along the optical axis 0, -0, and the distance ring 17 moves between the projections 17a provided on its inner peripheral surface and the The projection 16c of the lens drive ring 16, which is fitted between the hood attachment parts 18 via the ball 28, is pushed to move the first group of lens support frames 15 back and forth.

In this case, since the tip of the upper side 20a of the interlocking member 20 is fitted into the notch groove 16a (see FIG. 8) of the drive ring 16, movement in the rotational direction is inhibited and rotation is prevented. It does not move, but only moves back and forth in the optical axis direction. In this way, by moving the first lens group Lll back and forth, the relative relationship with the second and third group lenses Ll2, Ll3, and Ll4 is adjusted, and the object at a certain distance is focused. Next, the operation of performing a zoom operation by moving each of these lens groups along the optical axis 01-02 after focusing will be described. In this case, the zoom ring 19 is rotated around the optical axis 0, -02. When this is rotated, the interlocking member 20 integrated therewith also rotates, and since its upper side 20a fits into the notch groove 16a of the lens drive ring 16, the lens drive ring 16 also rotates. do. When this rotates, the drive pin 1 planted on this inner peripheral surface
6b also rotates, pushing its inner edge along the cam slot 15a of the support frame 15 of the first lens group, and moving the support frame 15 in the front-rear direction. In this case, the support frame 15 does not rotate because the fixed roller 27 supported by the support shaft 27a installed in the inner tube 12a of the fixed frame 12 is fitted into the long hole 15b of the support frame 15. Moves only in the front and back direction. On the other hand, the drive rollers 22, 2 are supported by a support shaft 21 fixed to the tip of the lower side 20b of the interlocking member 20.
3 also rotates in the same direction as the zoom ring 19 rotates.

When the drive rollers 22, 23 rotate, the rollers 22, 23 push the inner edges of the cam slots 14a, 13a of the support frames 14, 13 that are fitted thereto, and the respective cam slots 14a, 13a The support frames 14 and 13 are moved back and forth along the . In this case as well, the support frames 13 and 14 move only in the front-back direction without rotating because the fixed rollers 25 and 26 are fitted into the elongated holes 13b and 14b, respectively. By rotating the zoom ring 19 in this manner, the support frames 13, 14, and 15 of the lenses of each group are simultaneously moved in the front and rear directions, thereby making it possible to easily perform a zoom operation. Note that the amount of relative movement of the lens support frame of each group can be precisely determined by designing the shape of the cam slot in the optical design of the zoom lens system.

As explained above, the zoom lens barrel of the present invention successfully achieves the intended purpose by minimizing eccentricity due to movement of each lens group without increasing the overall shape. .

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing examples of the configuration of a conventional lens support frame, FIG. 3 is a cross-sectional view of a zoom lens barrel showing an embodiment of the present invention, and FIG. FIG. 5 is a perspective view of the movable lens support frame of the second group. FIG. 6 is a perspective view of the movable lens support frame of the third group. FIG. 7 is a perspective view of the lens support frame of the first group, FIG. 8 is a perspective view of the lens drive ring,
FIG. 9 is a plan view showing how the lens support frame of the first group shown in FIG. 7 and the lens driving ring shown in FIG. 8 are fitted together. 11...Zoom lens barrel, 12...
Fixed frame, 13... Second group movable lens support frame,
14... Third group movable lens support frame, 13a,
14a, 15a...cam slot, 15...
・First group lens support frame, 16... Lens drive ring, 19... Zoom ring, 20... Interlocking member, 22, 23... Drive roller, 30・
...Spring spring, 12d...Through hole (
circumferential groove).

Claims (1)

[Scope of Claims] 1. In a zoom lens barrel having at least two movable lens groups, one of the movable lens groups is held and is allowed to move only in the optical axis direction with respect to a fixed frame. The first lens support frame holds a first lens support frame and another movable lens group of the movable lens groups, and is fitted in an overlapping manner within the first lens support frame and can only move in the optical axis direction. a second lens support frame that is allowed, a first cam slot provided in the first lens support frame for moving the frame in the optical axis direction, and a hole bored in the second lens support frame. a second cam slot for moving the frame in the optical axis direction; a first driving roller that fits into the first cam slot; and a first driving roller that is integrated with the first driving roller. a second driving roller that is formed as follows and fits into the second cam slot;
a zoom ring that is rotatably operated from the outside, and a zoom ring that includes the first driving roller and the second driving roller.
A zoom lens barrel comprising: an interlocking member that connects the drive roller to the drive roller.