JPH09189835A - Lens driving device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the pressing force of an elastic member when a lens supporting frame is moved forward and backward by arranging the elastic member and a tapered member on which a tapered surface corresponding to the forward and backward moving quantity of the lens supporting frame is formed between the lens supporting frame and a rotary ring. SOLUTION: Ring-like plates 38 and 40 are arranged between a moving frame body 24 and a focus ring 34. Leaf springs 44 are formed on the plate 38 and the tapered members 46 are formed on the plate 40. The plate 40 is fixed to the ring 34 so that the tapered members 46... are faced to the springs 44 and the pawls 45 of the springs 44 are pressed and made to abut on the tapered surfaces 48 of the tapered members 46. The tapered surface 48 of the tapered member 46 is formed so that the angle thereof is adjusted to the lead of a helicoid screw. Thus, even when the plate 38 approaches the plate 40 or it is separated from the plate 40 because of the turning action of the ring 34, a distance L between a position on the tapered surface 48 on which the pawl 45 abuts and the plate 38 is not changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device for a camera, and more particularly, to moving a movable lens held by a lens support frame back and forth in the optical axis direction to adjust focus and zoom.
Alternatively, the present invention relates to a lens driving device for a camera that performs macro photography.

[0002]

2. Description of the Related Art Focus adjustment of a camera is performed by moving a focus lens of a photographing lens back and forth in an optical axis direction, and zoom adjustment is performed by moving a variator lens and a compensator lens while maintaining a predetermined optical relationship. It is done by Further, as the photographing lens, there is one in which a relay lens is moved in the optical axis direction to enable macro photographing.

By the way, of the above-described lens driving devices, for example, a focus lens driving device is constructed as follows. That is, the lens support frame holding the focus lens is supported by the guide bar so as to be movable back and forth in the optical axis direction, and the lens support frame and the focus ring are screwed and connected via a helicoid screw. Therefore, when the focus ring is rotated by a motor or manually, the lens support frame (focus lens) moves back and forth in the optical axis direction by the rectilinear action of the helicoid screw and the guide bar.

Further, in the lens driving device, since it is difficult to focus due to backlash due to backlash between the helicoid screws, an elastic member such as a coil spring is arranged between the focus ring and the lens support, and this elastic member is used. The backlash is removed by the urging force of.

[0005]

However, in the conventional lens driving device for a camera, the urging force of the elastic member changes according to the amount of movement of the lens, and the torque changes due to the change in the urging force. When the lens moves to a position where the operability is not good and the biasing force of the elastic member is large, the biasing force causes the lens to collapse.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lens driving device for a camera capable of keeping the biasing force of an elastic member constant regardless of the position of the lens. .

[0007]

In order to achieve the above-mentioned object, the present invention provides a taking lens barrel and a lens support frame that is moved back and forth in the optical axis direction by being guided by a guide member in the taking lens barrel. A rotation ring connected to the lens support frame to move the lens support frame back and forth in the optical axis direction by being rotated, and the rotation ring disposed between the lens support frame and the rotation ring. An elastic member for removing play at the connecting portion between the rotary ring and the rotary ring; and a tapered surface that is slidably contacted with the elastic member by the rotation of the rotary ring and that corresponds to the front-back movement amount of the lens support frame. And a taper member that makes the biasing force of the elastic member uniform by changing the contact position between the elastic member and the tapered surface in accordance with the amount of forward and backward movement of the frame.

According to the present invention, when the rotary ring is rotated,
The lens support frame moves back and forth in the optical axis direction. When the lens support frame is moved, the play in the connecting portion between the lens support frame and the rotary ring is removed by the urging force of the elastic member. Further, the elastic member slides along the taper surface of the taper member, and the contact position with the taper surface is changed according to the amount of front-rear movement of the lens support frame, so that the biasing force becomes uniform. Therefore, the present invention
The biasing force of the elastic member can be kept constant regardless of the position of the lens.

According to a second aspect of the invention, a straight-moving helicoid is adopted as the lens driving device. in this case,
The rotary ring is a helicoid ring, and the helicoid ring and the lens support frame are screwed and coupled via a helicoid screw. Therefore, when the helicoid ring is rotated, the lens support frame moves in the optical axis direction by the action of the helicoid screw. In such a lens driving device,
The backlash between the helicoid screws is removed by the urging force of the elastic member, and the urging force of the elastic member is kept constant regardless of the position of the lens by the action of the taper surface of the taper member.

According to a third aspect of the present invention, a focus lens is used as the lens. The lens support frame of the focus lens is moved by the movement of the straight-moving helicoid, and the biasing force of the elastic member during the movement is tapered. The taper surface of the member keeps it constant.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a lens driving device for a camera according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an example of a photographing lens device to which a lens driving device for a camera according to an embodiment of the present invention is applied. In the photographing lens device 10 shown in the figure, a first lens 14, an iris unit 16, and a second lens 18 are arranged in order from the front of the cover 12 along an optical axis P, and the rear of the cover 12 (the right end in the figure). Part) and a mount ring 20 provided on the camera body (not shown). Further, in the photographing lens device 10, the first lens 14 and the second lens 18 constitute a focus lens.

The first lens 14 is supported in a lens support frame 22 formed in a cylindrical shape, and the lens support frame 22 is fixed in a moving frame body 24 formed in a substantially cylindrical shape. ing. Similarly, the second lens 18 is also supported in the cylindrical lens support frame 28, and the lens support frame 2
8 is also fixed in the moving frame body 24. The moving frame body 24 is fixed to the cover 12 with screws 26. Further, a key plate 19 for restricting rotation of the moving frame body 24 is provided between the moving frame body 24 and the mount ring 20, and the key plate 19 allows the moving frame body 2 to move.
4 is guided so as to be able to move straight in the optical axis P direction. Therefore, the moving frame 24 is guided by the key plate 19 and the optical axis P
When moved back and forth in the direction, the first and second lenses 14, 1
8 moves back and forth together with the cover 12 in the optical axis P direction. As a result, focus adjustment is performed.

The iris unit 16 is arranged between the first lens 14 and the second lens 18, and is driven by the driving force from the galvanometer 30 to adjust to a desired aperture value. The galvanometer 30 is installed in a space portion 32 formed between the moving frame body 24 and the cover 12. On the outer peripheral surface of the rear part of the moving frame 24,
The helicoid screw 25 is formed. The helicoid screw 25 is screwed into a helicoid screw 35 formed on the small-diameter inner peripheral surface of the focus ring 34. Further, the helicoid screw 3 is also attached to the large-diameter inner peripheral surface of the focus ring 34.
7 is formed, and the helicoid screw 37 is screwed into the helicoid screw 21 formed on the outer peripheral surface of the mount ring 20. Therefore, when the focus ring 34 is rotated, the helicoid screws 21 and 37 move the focus ring 34 in the front-rear direction with respect to the mount ring 20, and the helicoid screws 25 and 35.
The moving frame 24 moves in the front-rear direction with respect to the focus ring 34 by the action. By combining these two operations, the first and second lenses 14 and 18 are moved to a predetermined focusing position.

On the other hand, between the moving frame 24 and the focus ring 34, two ring-shaped plates 38 and 40 are provided.
Is arranged. The plate 38 is fixed to the side surface of the flange portion 42 of the moving frame 24, and the plate 4
0 is fixed to the front side surface of the focus ring 34 facing the plate 38. The plates 38, 4 are shown in FIG.
The development view of 0 is shown. As shown in FIG.
Three leaf springs 44, 44, 44, which are elastic members, are formed on the. The leaf springs 44, 44 ... Are integrally formed with the plate 38 at equal intervals, and the tip claws 45, 45 ... Are bent toward the plate 40.

The plate 40 has taper members 46, 4
6, 46 are integrally formed with the plate 40 at equal intervals.
The plate 40 includes leaf springs 44, 44 of the plate.
... so that the taper members 46, 46 ... face each other, and the claws 45, 45 ... of the leaf springs 44, 44 ... are pressed against the taper surfaces 48, 48 ... of the taper members 46, 46 .... Then, it is fixed to the focus ring 34.

Therefore, an urging force is generated in the leaf springs 44, 44 ... And this urging force is transmitted to the focus ring 34 via the plate 40. As a result, the backlash between the helicoid screw 25 and the helicoid screw 35 described above is removed by the biasing force. By the way, the taper surface 48 of the taper member 46 is formed at an angle corresponding to the amount of forward and backward movement of the lenses 14 and 18. That is, the tapered surface 48 is formed at an angle that matches the leads of the helicoid screws 25 and 35. As a result, the rotation of the focus ring 34 causes the plate 38 to move to the plate 4.
The distance between the plate 38 and the position on the tapered surface 48 with which the claw 45 of the leaf spring 44 is abutted, even when approaching 0 (FIG. 3A) or moving away from 0 (FIG. 3B). L does not change. Therefore, the biasing force applied from the leaf spring 44 becomes uniform regardless of the positions of the lenses 14 and 18.

Next, the operation of the lens driving device constructed as described above will be described. When the focus ring 34 is rotated, the lenses 14 and 18 are moved back and forth in the optical axis P direction by the rectilinear action of the helicoid screws 21 and 37, the helicoid screws 25 and 35, and the key plate 19 to move to a predetermined position. It is located at the focus position. During such movement of the lenses 14 and 18, the backlash between the helicoid screws is removed by the urging force of the leaf spring 44 formed on the plate 38.
4 and 18 are securely held in the focus position. Further, as shown in FIG. 3, the leaf spring 44 slides along the taper surface 48 of the taper member 46 formed on the plate 40, so that the biasing force thereof becomes uniform.

Therefore, in this embodiment, the lens 14,
The urging force of the leaf spring 44 can be kept constant regardless of the movement position of 18. As a result, the operation feeling of the focus ring 34 becomes constant, and since an excessive biasing force is not applied to the lenses 14 and 18, the lenses 14 and 1 are
8 can be prevented from falling. In this embodiment,
We have adopted a linear helicoid mechanism with a helicoid screw as the lens driving device, but it is not limited to this.
For example, a mechanism having a mechanism for moving the lens support frame by rotating the cam can be applied.

Although the lens driving device for the lens has been described in the present embodiment, the present invention is not limited to this. For example, in the case of a zoom lens device that performs zooming by rotating the cam barrel, play between the variator lens and the compensator lens with respect to the cam groove of the cam barrel is removed by the leaf spring 44 of the present embodiment, and the leaf spring is used. The biasing force of 44 may be made uniform by the taper member 46.

Further, in the present embodiment, the movable frame 24 and the plate 38 are formed separately, but they may be formed integrally, and similarly, the focus ring 34 and the plate 40 may be formed integrally. good. Also, in the case of a zoom lens device that performs macro shooting by moving the relay lens in the optical axis direction,
The lens driving device of the present embodiment may be applied as the macro mechanism of the relay lens.

[0021]

As described above, according to the lens driving device for a camera of the present invention, the elastic member is slid along the tapered surface corresponding to the amount of forward and backward movement of the lens support frame. The urging force of the elastic member can be kept constant regardless of the position.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a photographing lens device to which a lens driving device for a camera according to an embodiment of the present invention is applied.

FIG. 2 is a development view showing an embodiment of a plate on which a leaf spring and a taper member are formed.

FIG. 3 is a cross-sectional view of essential parts showing a positional relationship between a leaf spring and a taper member corresponding to lens movement.

[Explanation of symbols]

 10 ... Photographing lens device 12 ... Covers 14, 18 ... Lens 16 ... Iris unit 20 ... Mount ring 24 ... Moving frame 34 ... Focus ring 38, 40 ... Plate 44 ... Leaf spring 46 ... Tapered member 48 ... Tapered surface

Claims (3)

[Claims] 1. A photographic lens barrel, a lens support frame which is guided by a guide member in the photographic lens barrel and moves back and forth in the direction of the optical axis, and by being connected to the lens support frame and rotated. A rotary ring that moves the lens support frame back and forth in the optical axis direction, and an elastic member that is disposed between the lens support frame and the rotary ring and that removes play in the connecting portion between the lens support frame and the rotary ring. By the rotation of the rotary ring, a taper surface is formed which is slidably contacted with the elastic member and corresponds to the front-rear movement amount of the lens support frame, and the elastic member and the taper surface correspond to the front-rear movement amount of the lens support frame. A lens driving device for a camera, comprising: a taper member that changes a contact position to make the biasing force of the elastic member uniform. 2. The lens of a camera according to claim 1, wherein the rotating ring is a helicoid ring, and the helicoid ring is screwed to the lens support frame through a helicoid screw formed on the helicoid ring. Drive. 3. The lens driving device for a camera according to claim 2, wherein the lens supporting frame is a lens supporting frame of a focus lens.