JPS644082Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention provides a lens moving device, especially a zoom operation,
The present invention relates to a lens moving device for a lens barrel in which lens movement is controlled by a cam, such as in a focus operation.

Conventionally, in a lens barrel that moves the lens using this type of cam control, such as a zoom lens barrel, when the leading edge of the first lens group holding member receives an impact, the impact force is applied to the helicoid screw, etc. The cam groove and the cam follower are joined to the cam groove and the cam follower through the part, resulting in deformation of the movable cylinder and damage to the cam groove and cam follower.

Therefore, in order to improve impact resistance, a fixed tube or a member that is securely connected to the fixed tube, such as a screw connection, is placed forward of the tip of the first lens group holding tube, and the fixed tube is attached to the first lens group holding tube. Structures that prevent impact force from being applied are also known.

FIG. 1 shows such a conventional two-group zoom lens barrel. That is, the third lens group _L3 is held in the mount 1 having the attachment part 1a to the camera body, and the fixed tube 2 fixed to the mount 1 with screws etc. has the first lens group L3 on its inner diameter.
First moving frame 3 and second lens group L ₂ for L ₁
A second movable frame 4 is fitted so as to be slidable in the optical axis direction, and a cam follower 3a implanted in the first movable frame 3 and a cam follower 4a implanted in the second movable frame 4 are attached to the fixed barrel 2. A cam cylinder 5 is fitted into the linear guide grooves 2a and 2b provided in the fixed cylinder 2, respectively, and is rotatably fitted to the outer diameter part of the fixed cylinder 2.
They also fit into cam grooves 5a and 5b provided in the cam grooves 5a and 5b, respectively. A first holding frame 6 that holds the first lens group L ₁ is attached to the helicoid 3 on the inner diameter part of the first moving frame 3 .
b, and is connected to the outer periphery of the second fixed barrel 8 fixed to the tip of the fixed barrel 2 by screws. Protrusion 6a formed on frame 6
is inserted. Further, a zoom ring 9 is fixed to the outer periphery of the cam cylinder 5.

With such a configuration, when the focus tube 7 is rotated, the first holding frame 6 is also rotated, and it moves back and forth in the optical axis direction according to the lead of the helicoid 3b to perform focusing, and when the zoom ring 9 is rotated, the first holding frame 6 also rotates. , the cam groove 5a of the cam cylinder 5 and the linear guide groove 2a of the fixed cylinder 2
The first moving frame 3 and the first holding frame 6 are guided by the
However, the second moving frame 4 is similarly guided by the cam groove 5b and the linear guide groove 2b, and both move along the optical axis direction to perform zooming.

However, when an impact is applied to the first holding frame 6 due to an external force in the optical axis direction, the impact force is applied to the helicoid 3b.
The impact force is directly applied to the installed portion of the cam floor 3a, the cam follower 3a, and the cam groove 5a of the cam cylinder 5, deforming or damaging either of them. . For this purpose, the focus tube 7 is made to protrude long forward on the subject side so as not to apply such an impact force to the portion, and the first holding frame 6 is zoomed or focused in order to move forward. Even when the first holding frame 6 is moved, the focus cylinder 7 always covers and protects the first holding frame 6, and the impact force is applied to the focus cylinder 7 and received by the fixed cylinder 2.

This is because the focus tube 7 is formed to be rotatable relative to the fixed tube 2, so no matter how deeply the first holding frame 6 is retracted toward the image side, the focus tube 7 of the same length will protrude. As a result, the total length of the mirror section becomes longer, and in such a state, a sufficient amount of light is given to the first lens group _L1 ,
In addition, in order to provide the lens system with a satisfactory angle of view, it is necessary to make the focus tube 7 large in diameter, which increases the size of the lens barrel and increases its volume and weight. The accessories also had the disadvantage of having to be large in diameter, making them incompatible.

An object of the present invention is to eliminate the drawbacks of the conventional example and provide a lens barrel with a simple structure and impact resistance.

Hereinafter, embodiments of the present invention will be described based on the drawings.

Figures 2 to 4 show an embodiment of the lens barrel according to the present invention; Figure 2 is a longitudinal sectional view thereof, Figure 3 is an exploded perspective view of its main parts, and Figures 4a and 4b are respectively FIG. 2 is an enlarged plan view and an enlarged cross-sectional view of main parts.

In the figure, 21 is a mount having a mounting part 21a to the camera body, which is held by the third lens group _L3 . Reference numeral 22 denotes a fixed cylinder fixed to the mount 21 with screws or the like, and a first moving frame 23 for the first lens group L ₁ and a second moving frame 24 for the second lens group L ₂ are mounted on the inner diameter of the fixed cylinder. is fitted so as to be slidable in the optical axis direction, and linear guide grooves 22a and 22b are provided. A cam cylinder 25 is rotatably fitted onto the outer diameter portion of the fixed cylinder 22, and has cam grooves 25a and 25b formed therein. 26 is the first lens group
With the first holding frame holding L ₁ , the first moving frame 2
3 and protrudes forward of the optical axis. Reference numeral 27 denotes a focus tube, which is threadedly connected to a second fixed tube 28 fixed to the tip of the fixed tube 22 with a screw or the like, and has a linear guide groove 27a formed in the optical axis direction at the front inner circumference of the focus tube. The first holding frame 26 is inserted into the guide groove 27a.
A protrusion 26a protruding from the front part of the outer periphery is fitted,
Moreover, its tip does not protrude beyond the tip of the first holding frame 26. 29 is a zoom ring fixed to the outer periphery of the cam cylinder 25. 30 is the first moving frame 2
A cam follower is embedded on the outer circumferential surface of 3 with a screw 30' or the like and is made of an elastic member such as synthetic resin, and has a small diameter portion 30a that fits into the linear guide groove 22a of the fixed cylinder 22 and a cam groove of the cam cylinder 25. 25a, and a surface 30c connecting the small diameter part 30a and the large diameter part 30b is formed to have a small space with respect to the outer diameter part of the fixed cylinder 22. has been done. Therefore, the width of the cam groove 22a is larger than the width of the linear guide groove 22a so as to fit into the large and small diameters of the cam follower 30. A cam follower 31 is installed in the second movable frame 24 with screws or the like, and is fitted into the linear guide groove 22b of the fixed cylinder 22 and the cam groove 25b of the cam cylinder 25.

Next, the operation of this embodiment having the following configuration will be explained.

First, when the focus tube 27 is rotated, the first holding frame 26 rotates due to the engagement between its protrusion 26a and the linear guide groove 27a, and the first moving frame 23
Focusing is performed by moving forward or backward in the optical axis direction according to the lead of the helicoid 23a, and when the zoom ring 29 is rotated, the cam cylinder 25 is rotated.
The cam groove 25b and the linear guide groove 2 of the fixed cylinder 22
2b, the cam follower 31 of the second movable frame 24 moves along the optical axis direction together with the second movable frame 24, and is guided by the cam groove 25a of the cam barrel 25 and the linear guide groove 22a of the fixed barrel 22. The cam follower 30 of the first moving frame 23 is moved in the optical axis direction together with the first moving frame 23, and the first holding frame 26 connected by the helicoid 23a is also moved to perform zooming, which is different from the conventional example described above. The same is true.

By the way, when an impact force due to an external force in the optical axis direction is applied to the first holding frame 26, the impact force is transmitted to the first moving frame 23 via the helicoid 23a, and further transmitted to the cam follower 30.

The small diameter portion 30a of the cam follower 30 is fitted into the linear guide groove 22a of the fixed cylinder 22 and is not affected by the impact force, but the large diameter portion 30a of the cam follower 30 is not affected by the impact force.
Since 0b is fitted into the cam groove 25a of the cam cylinder 25, an impact force is applied thereto. As a result, the cam follower 30 is tilted, but the large diameter portion 30b and the small diameter portion 30
The surface 30c that connects the cam groove 25a and the cam follower 30 is brought into contact with the outer peripheral surface of the fixed cylinder 22 to disperse the applied impact force together with the elasticity of the cam follower 30, thereby reducing the influence on the cam groove 25a and the cam follower 30, and preventing damage thereto. Ru.

Further, instead of using the entire cam follower as an elastic member, an elastic member such as rubber may be fitted around the outer periphery of the metal roller.

As explained above, the present invention has a cam cylinder that controls the movement of the first lens group moving frame in the optical axis direction by rotation of the operating member, and a fixed cylinder in which the cam cylinder is fitted, and the first lens group It has a zoom mechanism in which a cam follower provided on the lens group moving frame is fitted into a linear guide groove provided on the fixed barrel and a cam groove provided on the cam barrel, and the lens holding frame protrudes in front of the optical axis. In a lens barrel connected in the optical axis direction to the first lens group moving frame to which the cam follower is fixed, the cam follower has a two-stage shape consisting of a large diameter portion and a small diameter portion on the distal end side, and the cam barrel is The cam groove width and the linear guide groove width of the fixed cylinder are arranged on the outer diameter side of the fixed cylinder, and the width of the cam groove is set so that the width of the cam groove is set to the linear guide groove so that the width of the cam groove and the linear guide groove width of the fixed cylinder fit into the large and small diameters of the cam follower. By making the lens large, the focus tube does not have to protrude forward and have a large diameter, and the first lens This has the effect of dispersing the impact force in the optical axis direction on the moving frame and preventing deformation and damage to the cam groove of the cam barrel and the cam follower of the first lens moving frame.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional zoom lens barrel, FIG. 2 is a longitudinal sectional view of an embodiment of the zoom lens barrel according to the present invention, and FIG. 3 is an exploded perspective view of the main parts thereof. Figures 4a and 4b are an enlarged plan view and an enlarged cross-sectional view of the main parts, respectively. _L1 ...first lens group, _L2 ...second lens group,
L ₃ ...Third lens group, 21...Mount, 22
... Fixed cylinder, 22a ... Straight guide groove, 23 ...
First moving frame, 24... Second moving frame, 25... Cam barrel, 25a, 25b... Cam groove, 26... First holding frame, 27... Focus barrel, 29... Zoom ring serving as an operating member , 30, 31...cam follower, 30a...small diameter part, 30b...large diameter part.

Claims (1)

[Claims for Utility Model Registration] 1. A cam barrel that controls the movement of a first lens group moving frame in the optical axis direction by rotation of an operating member, and a fixed barrel into which the cam barrel is fitted, and the first lens It has a zoom mechanism in which a cam follower provided on the group moving frame is fitted into a linear guide groove provided on the fixed barrel and a cam groove provided on the cam barrel, and a lens holding frame protruding forward of the optical axis is attached to the lens holding frame. In a lens barrel connected in the optical axis direction to the first lens group moving frame to which a cam follower is fixed, the cam follower has a two-stage shape consisting of a large diameter part and a small diameter part on the distal end side, and The cam groove width of the cam cylinder and the linear guide groove width of the fixed cylinder are arranged on the outer diameter side of the fixed cylinder, and the cam groove is arranged so that the cam groove width of the cam cylinder and the linear guide groove width of the fixed cylinder fit into the large and small diameters of the cam follower. A lens moving device for a lens barrel characterized by an increased width. 2. The lens moving device for a lens barrel according to claim 1, wherein the cam follower has an outer peripheral portion formed of an elastic member. 3. Utility model registration claim 1 or 2, characterized in that the surface connecting the large diameter part and the small diameter part of the cam follower is set to have a minute space from the outer peripheral surface of the fixed cylinder. A lens moving device for the lens barrel described above.