JP2001091812A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain desired actuation torque with simple constitution by forming a pawl part which can be elastically deformed in a radial direction in a lens frame and making the pawl part press the inner peripheral surface of a cam barrel. SOLUTION: The pawl part 80, which can be elastically deformed in the radial direction, is formed at the outer peripheral part of the lens frame 28. By inserting the lens frame 28 in the cam barrel 34, the pawl part 80 presses the inner peripheral surface of the cam barrel 34. Thus, resistance is given to the lens frame 28 moving in the cam barrel 34, and the desired actuation torque is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lens barrel,
In particular, the present invention relates to a lens barrel which performs zooming and focusing by rotating a manipulation ring to move a lens frame fitted into a fixed barrel back and forth.

[0002]

2. Description of the Related Art In a lens barrel which performs zooming and focusing by rotating an operation ring fitted on an outer peripheral portion of a fixed barrel to move a lens frame fitted on an inner peripheral portion of the fixed barrel back and forth, In order to prevent the operation ring from rotating carelessly, the operation ring is provided with resistance.

Conventionally, the resistance applied to the operating ring is determined by urging the operating ring fitted into the fixed cylinder in the optical axis direction by means of a corrugated spring or an O-ring so that the operating ring is formed on a step formed on the outer peripheral surface of the fixed cylinder. It is given by pressing against a part or the like.

[0004]

However, if a resistance is given to the operating ring by using a corrugated spring or an O-ring as in the prior art, there is a disadvantage that the number of parts increases and the cost increases. In addition, there is a disadvantage that as the number of parts increases, the number of assembling steps increases, and it takes time to assemble.

[0005] In addition, since a corrugated spring or an O-ring is interposed, there is a disadvantage that the lens barrel becomes large.

Further, since the operating ring is urged in the optical axis direction using a corrugated spring or an O-ring,
There is a disadvantage that the pressing load changes even by a slight change in the dimension in the optical axis direction, and the operating torque varies.

The present invention has been made in view of such circumstances, and has as its object to provide a lens barrel that can obtain a desired operating torque with a simple configuration.

[0008]

According to the present invention, in order to achieve the above object, a cam barrel fitted in a fixed barrel is rotated to move a lens frame fitted in the cam barrel back and forth along an optical axis. In the lens barrel to be moved, the lens frame has a claw that elastically deforms in a radial direction. When the lens frame is fitted into the cam cylinder, the claw presses the inner peripheral surface of the cam cylinder to rotate the cam cylinder. It is characterized by giving a predetermined resistance sometimes.

According to the present invention, when the lens frame is fitted into the cam barrel, the claw formed on the lens frame presses the inner peripheral surface of the cam barrel. Thereby, resistance is given to the lens frame during rotation in the cam barrel, and a desired operating torque can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a lens barrel according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side sectional view of a lens barrel according to the present embodiment. The lens barrel 10 is a varifocal type lens barrel, and is mainly used for a monitoring camera. As shown in FIG. 1, a fixed lens group 14, a variable power lens group 16, a relay lens group 18, and a focus lens group 20
Are arranged in order. An iris device 24 is disposed between the variable power lens group 16 and the relay lens group 18.

The fixed barrel 12 comprises a front fixed barrel 12A and a rear fixed barrel 12B. The rear fixed barrel 12B is fixed to the rear end of the front fixed barrel 12A with screws 22.

A lens frame 26 for holding the fixed lens group 14
Are fixed to the distal end of the front fixed cylinder 12A by a snap fit 26A.

The lens frame 2 for holding the zoom lens group 16
8 is provided with three cams 30, 30, 30 at regular intervals on its outer peripheral surface. The three cams 30, 30, 30 are respectively composed of three straight grooves 36, 36, 36 formed in the cam cylinder 34 and three cam grooves formed in the inner peripheral surface of the front fixed cylinder 12A. 38, 38,
38. The cam cylinder 34 is a front fixed cylinder 12.
A is rotatably arranged inside A, and a pin 40 is attached to an outer peripheral portion thereof. The pin 40 is inserted into a long hole 42 formed in the front fixed cylinder 12 </ b> A.
It is inserted in. The zoom ring 44 is attached to the front fixed cylinder 1
It is rotatably arranged on the outer periphery of 2A, and a knob 44A is attached to the outer periphery.

With the above arrangement, when the zoom ring 44 is rotated, the rotation is transmitted to the cam cylinder 34 via the pin 40, and the cam cylinder 34 rotates. Then, when the cam cylinder 34 rotates, the lens frame 28 moves back and forth by the action of the cam groove 38 and the straight groove 36, thereby performing zooming. At this time, the lens frame 28 moves inside the cam cylinder 34 while receiving resistance by the action of a claw portion described later. Therefore, the lens frame 28 does not move carelessly, and the lens frame 28 is always fixed at a fixed position in a normal state.

The lens frame 4 for holding the relay lens group 18
6 is fixed to the front end of the inner cylinder 48 inserted and arranged in the rear fixed cylinder 12B. The inner cylinder 48 has a flange 48A formed at the rear end thereof.
Are fixed to the rear end surface of the rear fixed cylinder 12B with screws 50.

The lens frame 52 for holding the focusing lens group 20 has three cams 54, 54, 54 attached at regular intervals on the outer peripheral surface thereof. This 3
The main cams 54, 54, 54 have three straight grooves 56, 56, 56 formed on the inner cylinder 48 and three cam grooves 60, 60, 60 formed on the inner peripheral surface of the cam cylinder 58. Mated. The cam cylinder 58 is rotatably arranged on the outer peripheral portion of the inner cylinder 48, and a connecting arm 62 is connected to the outer peripheral portion. The connecting arm 62 is connected to the rear fixed cylinder 12.
B is inserted into an arc-shaped long hole 64 formed on the front end surface of B, and its front end is connected to a focus ring 66. The focus ring 66 is rotatably arranged on the outer peripheral portion of the front fixed cylinder 12A, and a knob 66A is attached to the outer peripheral portion.

With the above configuration, the focus ring 66
Is rotated, the rotation is transmitted to the cam barrel 58 via the connecting arm 62, and the cam barrel 58 rotates. And
When the cam cylinder 58 rotates, the lens frame 52 moves back and forth by the action of the cam groove 60 and the straight groove 56, and focusing is performed.

A connecting pin 70 is connected to the chrysanthemum seat 68 of the iris device 24. The connecting pin 70 is inserted into a long hole 72 formed on the outer peripheral surface of the rear fixed cylinder 12B, and the distal end thereof is connected to an iris ring 74. The iris ring 74 is rotatably disposed on the outer peripheral portion of the rear fixed barrel 12B, and has a knob 7 on its outer peripheral surface.
4A is attached. When the iris ring 74 is rotated, the rotation of the iris ring 74 is performed via the connecting pin 70.
8 and the chrysanthemum seat 68 rotates. When the chrysanthemum seat 68 rotates, the aperture blades 76 of the iris device 24 are operated, and iris adjustment is performed.

FIG. 2 is a perspective view of the lens frame 28 as viewed from the front side, and FIG. 3 is a front view showing a state of the lens frame 28 fitted in the cam barrel 34.

As shown in FIGS. 2 and 3, the lens frame 28
Has a double-pipe structure including an inner frame 28A and an outer frame 28B. The variable power lens group 16 is held on the inner peripheral portion of the inner frame 28A. This lens frame 28
Are integrally formed of an elastically deformable material such as resin, and the outer frame 28B has three claw portions 80, 8
0 and 80 are formed at equal intervals.

The claw portion 80 is formed integrally with the lens frame 28 by forming a pair of slits 82 in the outer frame 28B. The slits 82 have a predetermined length along the optical axis from the end of the zoom ring 44 and extend through the outer and inner peripheral surfaces of the outer frame 28B. Thereby, the claw portion 80 is formed so as to be elastically deformable in the radial direction. The claw portion 80 formed so as to be elastically deformable is integrally formed with a mountain-shaped projection 84 on the outer periphery of the distal end portion.

The lens frame 28 configured as described above is
It is attached to the front fixed cylinder 12A as follows.

First, three cams 30, 30, 30 formed on the lens frame 28 are fitted into three straight grooves 36, 36, 36 formed on the cam cylinder 34. Then, the lens frame 28 is pushed into the cam cylinder 34 along the optical axis.

When the lens frame 28 is pushed into the cam barrel 34, the projection 84 of the claw 80 formed at the tip of the lens frame 28 is pressed against the inner peripheral surface of the cam barrel 34 to reduce the diameter. The reduced diameter projection 84 presses the inner peripheral surface of the cam cylinder 34 by the elastic restoring force, whereby a frictional force is generated on the moving lens frame 28, and resistance is generated.

When the lens frame 28 is inserted into the cam cylinder 34 as described above, the cam 3 formed on the lens frame 28
0 protrudes from the outer peripheral portion of the cam cylinder 34 via the straight groove 36. Next, the cam 30 is fitted into a cam groove 38 formed in the front fixed cylinder 12A. And the cam cylinder 34
Is pushed into the front fixed barrel 12A along the optical axis.

When the cam cylinder 34 is housed in the front fixed cylinder 12A, a long hole 42 formed in the front fixed cylinder 12A is formed.
The pin 40 is connected to the outer peripheral surface of the cam cylinder 34 via the.
Then, a zoom ring 44 is provided on the outer peripheral portion of the front fixed cylinder 12A.
And the pin 40 is fitted into a groove 45 formed on the inner peripheral surface of the zoom ring 44.

The mounting of the lens frame 28 is completed as described above, and the lens frame 28 moves back and forth along the optical axis with the rotation of the zoom ring 44. At this time, the lens frame 28
Since frictional resistance is generated when moving, zoom ring 4
4 cannot be rotated unless a force greater than a predetermined torque is applied, and does not rotate carelessly.

As described above, the lens barrel 10 of the present embodiment
According to this, the desired operating torque can be generated in the zoom ring 44 by the claw portion 80 integrally formed on the lens frame 28 without requiring a separate urging member.
Thus, the cost can be reduced, and the number of assembly steps can be reduced.

In the present embodiment, an example has been described in which the present invention is applied to the lens frame 28 holding the zooming lens group 16. However, other embodiments such as the lens frame 52 holding the focusing system lens group 20, etc. It can also be applied to a lens frame.

In the present embodiment, the number of the claw portions 80 formed on the lens frame 28 is three. However, the present invention is not limited to this, and two or four claw portions 80 may be provided.

Further, in the present embodiment, the lens frame 28 has a double tube structure composed of an inner frame 28A and an outer frame 28B. In order to speed up the drying of the lens frame 28 and improve the processing accuracy, the lens frame 28 is often made to have a double tube structure as in the present embodiment. This is called so-called "meat peanut", and the present invention can be configured by effectively utilizing this meat peanut. It should be noted that instead of having a double tube structure as in the present embodiment, only the inside of the claw portion 80 may be formed in a hollow shape.

[0033]

As described above, according to the lens barrel of the present invention, a desired operating torque can be obtained without adding any additional parts by integrally forming the claw portion with the lens frame. . In addition, the cost can be reduced, and the number of assembling steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a lens barrel according to an embodiment of the present invention.

FIG. 2 is a perspective view of the lens frame viewed from the front side.

FIG. 3 is a front view showing a state of a lens frame fitted into a cam barrel.

[Explanation of symbols]

10: lens barrel, 12: fixed barrel, 12A: front fixed barrel, 12B: rear fixed barrel, 14: fixed lens group, 16 ...
Variable power lens group, 18 relay lens group, 20 focus lens group, 24 iris device, 26 lens frame, 28A inner frame, 28B outer frame, 30 cam, 34 ...
Cam cylinder, 38: cam groove, 40: pin, 42: long hole, 44
... zoom ring, 66 ... focus ring, 74 ... iris ring, 80 ... claw, 82 ... slit, 84 ... projection

Claims (1)

[Claims] 1. A lens barrel in which a lens barrel fitted in a cam barrel is moved back and forth along an optical axis by rotating a cam barrel fitted in a fixed barrel, wherein the lens frame is elastically deformed in a radial direction. A lens barrel having a claw portion that presses an inner peripheral surface of the cam tube when the lens frame is fitted into the cam tube to apply a predetermined resistance when the cam tube rotates.