JP2003084186A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel having a high strength against an external force by forming a flat abutting surface on the side part of a cam follower. SOLUTION: A vertical area 9b is arranged in the cam groove 9 of a fixed cylinder 6 so as to be vertically formed in an optical axis O direction, and the can follower 23 with the flat abutting surface 23a formed on the side part vertical to the optical axis O direction is engaged with the cam groove 9. Then, the abutting surface 23a of the cam follower 23 comes in wide contact with the side wall 9d of the cam groove 9. Then, in the case the external force is applied on the lens barrel and the external force is transmitted from the cam follower 23 to the cam groove 9, the external force is dispersedly transmitted to the cam groove 9, then, the contact part between the cam follower 23 and the cam groove 9 is hardly broken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel used in a lens optical system of a camera.

[0002]

2. Description of the Related Art As a related art lens barrel of a camera, a cam follower formed in a lens moving barrel is inserted into a cam groove formed in the cam barrel as described in Japanese Patent Laid-Open No. 2001-42189. It is known that the lens moving barrel can be extended and retracted with respect to the cam barrel by rotating the cam barrel. The cam follower has a tapered truncated cone shape. Further, the cam groove has a tapered tapered cam surface.

[0003]

In such a lens barrel, as shown in FIG. 10, a lens moving barrel 101 is used.
When the cam follower 10 receives an external force in the direction of the optical axis O,
Since 2 is tapered, the lens moving barrel 101 is easily deformed inward and the cam barrel 103 is easily deformed outward. Further, as shown in FIG. 11, since the cam follower 102 has a circular cross section and the cam follower 102 and the cam groove 104 are in contact with each other at one point, the load is concentrated on the contact portion 105 when receiving an external force. This is likely to cause deformation or damage.

Therefore, the present invention has been made in order to solve such a problem, and an object thereof is to provide a lens barrel having high strength against external force.

[0005]

In order to achieve such an object, a lens barrel according to the present invention comprises a first cylinder and a second cylinder which accommodate a lens optical system and are arranged in multiplex inside and outside. At least the cam follower formed on the peripheral surface of the second cylindrical body is engaged with the cam groove formed on the peripheral surface of the first cylindrical body, and the first follower is rotated according to the shape of the cam groove by the rotation of the second cylindrical body. In a lens barrel in which two cylinders can be extended and retracted with respect to a first cylinder, a cam groove has a vertical region formed in a part thereof in a direction perpendicular to the optical axis direction of the lens optical system. Has a flat contact surface that contacts the side wall of the vertical region of the cam groove on the side perpendicular to the optical axis direction.

Further, the lens barrel according to the present invention is characterized in that the side wall of the vertical region is formed perpendicular to the optical axis direction, and the contact surface of the cam follower is formed perpendicular to the optical axis direction. .

Further, the lens barrel according to the present invention is characterized in that the cam follower is a projection whose cross section is a parallelogram.

According to these aspects of the invention, the cam follower of the second cylindrical body has the flat contact surface on the side portion perpendicular to the optical axis direction, so that when the external force is applied to the second cylindrical body. If the cam follower is located in the vertical region of the cam groove, the planar contact surface will contact the side wall of the cam groove in a wide range. Therefore, the force is dispersed and transmitted from the cam follower to the cam groove, and the contact portion between the cam follower and the cam groove is less likely to be damaged.

Further, when an external force acts on the second cylinder by the contact surface of the cam follower and the side wall of the cam groove contacting each other perpendicularly to the optical axis direction, the contact portion between the cam follower and the cam groove moves in the optical axis direction. Only the force is transmitted. Therefore, at the contact portion, it is possible to prevent a problem in which the second cylindrical body is deformed outward and the first cylindrical body is deformed inward, and damage due to such deformation can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same elements are designated by the same reference numerals and the description thereof will be omitted. Further, the dimensional ratios in the drawings do not always match those described. (First Embodiment) FIG. 1 shows an explanatory view of a lens barrel according to this embodiment. As shown in the figure, the lens barrel 1 according to the present embodiment is used for a photographing optical system of a camera 2. The lens barrel 1 contains a first lens group 3, a second lens group 4 and a third lens 5. The first lens group 3, the second lens group 4, and the third lens 5 are lens optical systems sequentially arranged along the optical axis O, and constitute a photographing optical system of the camera 2.

The lens barrel 1 includes a fixed frame 6 fixed to the main body of the camera 2, an intermediate barrel 7 that can be extended and retracted with respect to the fixed frame 6, and a movable extension and extension with respect to the intermediate barrel 7. And a tube 8. The fixed frame 6, the intermediate cylinder 7 and the movable cylinder 8 are arranged in multiplex inside and outside with the optical axis O as the center.

The fixed frame 6 is a tubular member having an opening 10 at one end and an opening at the other end. An image plane 11 of the photographing optical system is formed in the opening 10. The opening 10 is used as a mounting space for mounting the holding frame 13 of the CCD 12, which is an image sensor. The holding frame 13 is the CCD 1
It is a frame body for holding 2 and is configured separately from the fixed frame 6 and attached to the opening 10 of the fixed frame 6. The image plane 11 may be set inside the fixed frame 6 with respect to the opening 10.

The holding frame 13 is attached to the opening 10 by being held by the edge of the opening 10, being pressed by the holding plate 14. As a result, the CCD held by the holding frame 13
12 is arranged on the image plane 11.

A cam groove 9 is formed on the peripheral surface of the fixed frame 6. The cam groove 9 is formed, for example, penetrating inside and outside the peripheral surface of the fixed frame 6. The cam follower 23 of the intermediate cylinder 7 is inserted into the cam groove 9. The cam follower 23 is a projection that projects outward from the outer peripheral surface of the intermediate cylinder 7. In addition,
The shapes and the like of the cam groove 9 and the cam follower 23 will be described later.

A pin 24 is provided at the tip of the cam follower 23.
Is attached. The pin 24 is a member for transmitting the rotational force to the intermediate cylinder 7, and is inserted into the vertical groove 16 a formed in the rotary cylinder 16. The rotating cylinder 16 is a fixed frame 6
It is a cylindrical member disposed on the outside of and rotates when driven by a drive source such as a motor. The vertical groove 16a is formed by recessing the inner peripheral surface of the rotary cylinder 16 and extends in the direction of the optical axis O of the photographing optical system, that is, in the optical axis direction.

As the rotary cylinder 16 rotates, the pin 2
4 and the cam follower 23 move in the circumferential direction and along the cam groove 9 in the optical axis direction. As a result, the intermediate cylinder 7 moves in the optical axis direction while rotating, and is extended or retracted with respect to the fixed frame 6.

A vertical groove 17 extending in the optical axis direction is formed on the inner peripheral surface of the fixed frame 6. The vertical groove 17 is a groove for stopping the rotation of the straight advance key ring 18 and guiding the straight advance key ring 18 in the optical axis direction. The straight advance key ring 18 is an annular member having substantially the same diameter as the intermediate cylinder 7, and is rotatably locked to the intermediate cylinder 7 at the rear end of the intermediate cylinder 7. Therefore, the straight-ahead key ring 18 moves in the optical axis direction together with the intermediate cylinder 7 while allowing the intermediate cylinder 7 to rotate.

The straight key ring 18 has a support portion 18a extending forward. The support portion 18a is hooked on the rear end of the movable barrel 8 to prevent the movable barrel 8 from rotating. A pin 21 protruding from the outer peripheral surface is provided at the rear end of the movable barrel 8. The pin 21 is inserted into a cam groove 22 formed on the inner peripheral surface of the intermediate cylinder 7. The cam groove 22 is formed in a spiral shape along the inner peripheral surface of the intermediate cylinder 7, for example.

Even if the intermediate cylinder 7 rotates, the movable cylinder 8 does not rotate because it is supported by the straight key ring 18. However, the pin 21 moves in the optical axis direction according to the shape of the cam groove 22. As a result, the movable barrel 8 moves in the optical axis direction as the intermediate barrel 7 rotates, and is extended or retracted with respect to the intermediate barrel 7.

The first lens group 3 is fixed to the movable barrel 8 via a first lens holding frame 30 and the like. The first lens group 3 moves in the optical axis direction as the movable barrel 8 is extended and retracted. A second lens holding frame 40 that holds the second lens group 4 is fixed to the intermediate cylinder 7. Therefore, the second lens group 4 moves in the optical axis direction in accordance with the extension and retraction of the intermediate cylinder 7.

A focus motor 41 is attached to the second lens holding frame 40 by screwing or the like.
The focus motor 41 is a drive unit for moving the third lens 5 which is the focus lens of the photographing optical system in the optical axis direction, and is a range finder (not shown) installed in the camera 2 for measuring the distance to the subject. Drive based on the output signal of.

The rotary shaft 42 of the focus motor 41 has a thread groove formed on its peripheral surface and functions as a lead screw. A third lens holding frame 43 is screwed onto the rotating shaft 42. A shaft 44 installed in the second lens holding frame 40 penetrates the third lens holding frame 43. The shaft 44 functions as a guide shaft of the third lens holding frame 43 and a rotation preventing unit. When the rotation shaft 42 of the focus motor 41 rotates, the third lens holding frame 43 and the third lens 5 move in the optical axis direction along with the rotation.

FIG. 2 is a development view in which the intermediate cylinder 7 is developed in a plane shape. FIG. 3 is a perspective view of the cam follower 23 formed on the intermediate cylinder 7. FIG. 4 is a development view in which the fixed cylinder 6 is developed in a plane.

As shown in FIG. 2, at the end of the intermediate cylinder 7,
A plurality of cam followers 23 are formed, and for example, three cam followers 23 are formed at equal intervals in the circumferential direction. The cam follower 23 is configured as a protrusion having a parallelogram cross section. The cam follower 23 has a flat contact surface 23a formed on a side portion perpendicular to the optical axis direction. This contact surface 23a
Are raised vertically from the peripheral surface of the intermediate cylinder 7 and are perpendicular to the optical axis O. As shown in FIG. 3, a tapered tapered surface 23b is formed on a side portion of the cam follower 23 adjacent to the contact surface 23a.

As shown in FIG. 4, the cam groove 9 of the fixed barrel 6
Are formed in plural, for example, three are formed at equal intervals in the circumferential direction of the fixed cylinder 6. The cam followers 23 are inserted into the cam grooves 9 respectively, and the cam followers 23 are inserted along the forming direction thereof.
To move. The cam groove 9 is in the optical axis direction (direction of the optical axis O).
It has an inclined region 9a formed to be inclined with respect to and a vertical region 9b formed to be perpendicular to the optical axis direction.

As shown in FIG. 5, the inclined region 9 of the cam groove 9 is formed.
The side walls 9c, 9c in a are tapered so as to taper toward the outer peripheral side, and are shaped to fit with the tapered surface 23b of the cam follower 23.

As shown in FIG. 6, the vertical region 9 of the cam groove 9 is shown.
The side walls 9d and 9d in b are vertical surfaces that stand upright, and are shaped to fit with the contact surface 23a of the cam follower 23.

Next, the operation of the lens barrel according to this embodiment will be described.

In FIG. 1, when the rotary cylinder 16 rotates,
The rotational force is transmitted to the intermediate cylinder 7 via the pin 24 hooked in the vertical groove 16a of the rotary cylinder 16. This allows
The intermediate cylinder 7 rotates together with the rotary cylinder 16. When the intermediate cylinder 7 rotates, the cam follower 23 moves along the circumferential direction of the fixed cylinder 6.

Therefore, as shown in FIG. 4, when the cam follower 23 passes through the inclined region 9a of the cam groove 9, the intermediate cylinder 7 is extended from the fixed cylinder 6. At this time, the cam follower 23 is formed in a parallelogram, the side portion thereof is formed in parallel with the side wall of the inclined region 9a, and the cam follower 23 and the cam groove 9 are in contact with each other over a wide range, so that the intermediate cylinder 7 is connected to the cam follower 23. It is stably held by the fixed barrel 6 via. Further, even if an external force acts on the intermediate cylinder 7, the contact portion between the cam follower 23 and the cam groove 9 is not easily damaged.

When the intermediate cylinder 7 further rotates and the cam follower 23 reaches the vertical area 9b of the cam groove 9, the camera 2 is ready to take a picture. That is, when the intermediate cylinder 7 is extended, the first lens group 3, the second lens group 4, and the third lens 5 are moved to a position where an appropriate image can be taken.

When the cam follower 23 is in the vertical region 9b, even if the intermediate cylinder 7 rotates, the cam follower 23 does not move in the optical axis direction. For this reason, the intermediate cylinder 7 is not extended or retracted with respect to the fixed cylinder 6, but the rotation of the intermediate cylinder 7 causes the movable cylinder 8 to be extended or retracted with respect to the intermediate cylinder 7 to perform zooming.

Further, as shown in FIG. 7, the cam follower 2
When 3 is in the vertical region 9b, the contact surface 23a of the cam follower 23 is in wide contact with the side wall 9d of the cam groove 9, so that even if an external force acts on the intermediate cylinder 7, the cam follower 23
The force is dispersed and transmitted from the to the cam groove 9. Therefore, the contact portion between the cam follower 23 and the cam groove 9 is less likely to be damaged.

Further, as shown in FIG. 8, the cam follower 2
Since the contact surface 23a of 3 and the side wall 9d of the cam groove 9 are in contact with each other in the direction perpendicular to the optical axis direction, when an external force acts on the intermediate cylinder 7, the contact portion between the cam follower 23 and the cam groove 9 moves in the optical axis direction. Only the force is transmitted. Therefore, at the contact portion, it is possible to prevent the intermediate cylinder 7 from being deformed outward and the fixed cylinder 6 to be deformed inward, and it is possible to prevent damage due to such deformation.

As described above, according to the lens barrel 1 of the present embodiment, the cam follower 23 of the intermediate barrel 7 is formed with the planar contact surface 23a, so that the deformation or damage to the external force can be prevented. It is possible to have a high strength structure.

Although the case where the lens barrel according to the present invention is applied to a digital camera has been described in the present embodiment, the lens barrel according to the present invention is not limited to such a digital camera. It may be applied to optical devices other than cameras. (Second Embodiment) Next, a lens barrel according to a second embodiment will be described.

FIG. 9 is an explanatory view of the lens barrel according to this embodiment. As shown in the figure, the lens barrel according to the present embodiment has a structure substantially similar to that of the lens barrel according to the first embodiment, and has linear contact surfaces 23a, 23.
This is different from the lens barrel according to the first embodiment in that an oval cam follower 23 having a curved side portion between a is provided.

According to the lens barrel of this embodiment, since the cam follower 23 is oval, even if the inclined region 9b of the cam groove 9 is curved instead of being straight, the cam follower 23 can be moved in the inclined region 9b. It can be moved easily.

[0039]

As described above, according to the present invention, by forming a flat contact surface on the cam follower of the second cylindrical body, it is possible to prevent deformation and damage due to external force, and to prevent the lens barrel from being damaged. It can have high strength.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a lens barrel according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of an intermediate cylinder in the lens barrel of FIG.

FIG. 3 is an explanatory diagram of a cam follower in the lens barrel of FIG.

4 is an explanatory view of a fixed barrel and a cam groove in the lens barrel of FIG.

5 is a sectional view of a cam groove taken along line VV of FIG.

6 is a sectional view of a cam groove taken along line VI-VI of FIG.

FIG. 7 is an explanatory diagram of an operation of the lens barrel of FIG.

FIG. 8 is an explanatory diagram of an operation of the lens barrel of FIG.

FIG. 9 is an explanatory diagram of a lens barrel according to a second embodiment.

FIG. 10 is an explanatory diagram of a conventional technique.

FIG. 11 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1 ... Lens barrel, 2 ... Camera, 3 ... First lens group, 4 ...
Second lens group, 5 ... Third lens, 6 ... Fixed frame (first cylinder), 7 ... Intermediate cylinder (second cylinder), 8 ... Moving cylinder, 9 ... Cam groove, 9a ... Inclined region, 9b ... Vertical area, 9d ... Side wall, 2
3 ... Cam follower, 23a ... Contact surface, O ... Optical axis.

Claims (3)

[Claims] 1. A second cylinder having at least a first cylinder and a second cylinder which accommodate a lens optical system and are arranged in multiple layers inside and outside, wherein the second cylinder is provided in a cam groove formed on a peripheral surface of the first cylinder. A lens that engages a cam follower formed on the peripheral surface of the body and that allows the second cylinder to be extended and retracted with respect to the first cylinder according to the shape of the cam groove by rotation of the second cylinder. In the lens barrel, the cam groove has a vertical region formed in a part thereof in a direction perpendicular to the optical axis direction of the lens optical system, and the cam follower has a side portion perpendicular to the optical axis direction. A lens barrel having a planar contact surface that contacts the side wall of the vertical region of the cam groove. 2. The side wall of the vertical region is formed perpendicularly to the optical axis direction, and the contact surface of the cam follower is formed perpendicularly to the optical axis direction. A lens barrel to do. 3. The lens barrel according to claim 1, wherein the cam follower is a protrusion having a parallelogram cross section.