JP2000009985A - Lens barrel for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel for camera capable of effectively restraining the quantity of light advancing from the screwing part of a helicoid screw. SOLUTION: Helicoid screws 9b are formed to have three line cut off zones A on the inner peripheral surface of a cylindrical rotating member 9 rotated with an optical axis O as center. One light shielding wall 9c is formed along the thread line of the helicoid screw at one part of each zone A. Meanwhile, the helicoid screw is similarly formed to have three line cut off zones on the outer peripheral surface of the lens barrel inside which a lens is attached. Then, the member 9 and the lens barrel are screwed and constituted so that the lens barrel may be moved in the optical axis O direction by rotating the member 9. Therefore, even though the zone A of the member 9 is opposed to the line cut off zone of the lens barrel in a state where the member 9 is stopped, the quantity of the light advancing from space between them is restrained because the wall 9c exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel for a camera.

[0002]

2. Description of the Related Art A lens barrel for a camera in which a lens barrel is operated linearly in the direction of an optical axis to perform focus adjustment and zooming is known. As, a helicoid screw is formed on the outer peripheral surface of the lens barrel, and it is screwed to a helicoid screw formed on the inner peripheral surface of the cylindrical rotary member, and the cylindrical rotary member is centered on the optical axis. It is known that when rotated, a lens barrel is guided by guide means and is operated linearly in the optical axis direction. The present invention relates to a lens barrel for a camera provided with such a helicoid drive mechanism.

[0003] By the way, such a helicoid screw,
In the past, it was formed on all surfaces of the screwing region between the lens barrel and the cylindrical rotating member. However, recently, when the lens barrel and the cylindrical rotating member are manufactured from synthetic resin,
When the helicoid screw is formed on all surfaces of the screwing region, it has become a problem that the manufacturing cost of the mold becomes extremely high. In addition, when molding is performed using such a mold, it is necessary to remove the mold while rotating the mold at a predetermined speed in order to prevent damage to the threads at the time of release. There was also a problem that it took a long time.

Therefore, it has become common to manufacture such a cylindrical screw member using a mold called a split mold. According to this method, since a series of helicoid screw portions are formed by being divided into a plurality of dies, it is possible to move each of the dies in the radial direction at the time of release, thereby shortening the processing time. There are advantages. However, in the case of manufacturing with a normal split mold configuration, a molten resin material enters at the joint of the divided molds, and a projection called a burr is formed on a part of the screw shape. Would be. Such a situation is extremely difficult to avoid even when the mold is manufactured with high precision, since the mold is worn by repeated use. For this reason, there has been a problem that the mold needs to be frequently updated and secondary processing (burr removing processing) of parts is required.

Therefore, recently, when a cylindrical screw member is manufactured by using a split mold, a thread is not often formed near a contact portion with an adjacent mold. Therefore, in the cylindrical screw member manufactured in the split mold in this way, the screw thread is not continuously formed over the entire surface of the screwing region with the counterpart member, and the screw thread is not formed in the axial direction of the member. Along the way, a plurality of strips without any threads are formed. An example of a cylindrical screw member having such a shape is shown in FIG. FIG. 3 is an exploded view of a member in which a helicoid screw is formed on an outer peripheral surface. Since the helicoid screw is manufactured in a split mold divided into three, the helicoid screw is formed along the optical axis O. Three strips A are formed.

[0006]

As shown in FIG. 3, when the thread of a helicoid screw is formed as shown in FIG. In addition to eliminating the necessity of forming burrs that have an adverse effect, there is an advantage that the mold can be easily manufactured by increasing the width of the cut strip A as much as possible. However, when the member manufactured in such a manner is used for the above-described lens barrel and the cylindrical rotating member, there is a case where a serious problem may occur.

That is, in a lens barrel for a camera,
The cylindrical rotating member may be rotated to a certain rotation angle and stopped at that position, but at that time, if the missing band of the cylindrical rotating member and the missing band of the lens tube are opposed to each other,
An optical path substantially parallel to the optical axis is formed there. Therefore, if the light passing through such an optical path enters the optical path of the light passing through the photographing lens during photographing, a flare may be generated. In addition, during non-photographing, light passing through the photographing lens is generally blocked by shutter blades. However, depending on the configuration of a shutter unit in which a lens barrel is attached, the light enters from around the lens barrel. The emitted light may bypass the blade chamber of the shutter and reach the film surface, causing exposure by so-called light leakage.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a helicoid screw formed to have a plurality of strips on the outer peripheral surface of a lens barrel. A lens barrel for a camera that is screwed to a helicoid screw formed to have a plurality of strips on the inner peripheral surface of a cylindrical rotating member that is rotated about the optical axis, When the strip band of the cylindrical rotating member and the strip band of the lens barrel face each other, the amount of light that enters the inside from the space formed by them is
An object of the present invention is to provide a lens barrel for a camera which can be effectively suppressed.

[0009]

In order to achieve the above-mentioned object, the present invention has a helicoid screw formed on the inner peripheral surface so as to have a plurality of strips along the optical axis. A cylindrical rotating member rotated around the optical axis,
A helicoid screw that is screwed to the helicoid screw is formed on the outer peripheral surface so as to have a plurality of strips along the axial direction of the optical axis, and a lens is mounted inside, and by rotation of the cylindrical rotating member A lens barrel having a lens barrel linearly operated in the axial direction of the optical axis;
At least one light-shielding wall is formed on at least one of the strips along the thread of the helicoid screw. In this case, it is preferable that the light-shielding wall is formed in a strip band portion in a region where the helicoid screw of the cylindrical rotating member and the helicoid screw of the lens barrel are always screwed together.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the embodiments shown in FIGS. This example is
FIG. 1 is a cross-sectional view mainly showing a state in which the taking lens and the lens shutter are assembled as a unit, and FIG. It is an expanded view of a rotary member. In photographing, the left side of FIG. 1 is the subject side. In the following description, the left side of FIG. 1 will be referred to as the subject side, and the right side of FIG. 1 will be referred to as the film surface side.

In FIG. 1, a shutter chamber 3 formed between a shutter base plate 1 and an auxiliary base plate 2 accommodates two shutter blades serving also as a diaphragm. The base plates 1 and 2 are made of synthetic resin, have a ring shape when viewed from the subject side, and have circular openings 1a and 2a centered on the optical axis O at the center. I have. The exposure opening is regulated by the opening 2a having the smaller diameter. Various members are attached to the subject side of the shutter base plate 1, but since a large number of members need to be densely arranged, the shutter base plate 1 is provided with a predetermined space between the shutter base plate 1 and the support plate. 4 is attached.

The support plate 4 is made of a synthetic resin and has an extremely complicated shape. That is, similarly to the shutter base plate 1, it has an annular shape around the optical axis O. However, in actuality, in consideration of the arrangement of members attached thereto, a complicated uneven shape is formed in the left-right direction in FIG. ing. Therefore, when a cross section is taken as shown in FIG. 1, the entire shape cannot be understood, and only a part thereof appears at the lower position and the upper left position in FIG. Further, in order to understand the overall shape of the support plate 4, it is necessary to prepare and explain a plurality of drawings, but it is not necessary to understand so much to grasp the present invention. Required components that are not shown will be supplemented with text each time.

A lens driving motor 5 is mounted between the shutter base plate 1 and the support plate 4 and has an output shaft 5.
The gear 6 is attached to a. Further, a holding plate 7 is attached to the subject side of the support plate 4 by means not shown. The overall shape of the holding plate 7 is
As shown in the lower part of FIG. 1, a gear 8 is rotatably supported between the support plate 4 and an annular shape surrounding the photographing optical path. Further, although not shown, a plurality of gears constituting the speed reduction mechanism make the photographing optical path approximately 180 °.
, So that the rotation of the gear 6 is transmitted to the gear 8. The tooth portion 8a of the two tooth portions 8a and 8b formed on the gear 8 meshes with the gear of the speed reduction mechanism.

The cylindrical rotating member 9 is made of a synthetic resin,
The tooth portion 9a formed on the outer peripheral surface is the tooth portion 8b of the gear 8.
Is engaged. Also, on the inner peripheral surface of the cylindrical rotating member 9,
A helicoid screw 9b is formed using a split mold.
FIG. 2 is an expanded view of the cylindrical rotating member 9 for easy understanding of the inner peripheral surface.
As can be seen from FIG. 3, three strips A are formed on the inner peripheral surface along the axial direction of the optical axis O. Further, one light shielding wall 9c is formed along part of each helicoid screw 9b in a part of each of the strip belts A. The height of each light shielding wall 9c in the radial direction is equal to that of the helicoid screw 9b. It is about the same height as the thread. In addition, each light shielding wall 9c
Is slightly smaller than the width of the crest of the helicoid screw 9b.

The lens barrel 10 is made of a synthetic resin and has a taking lens mounted inside. A helicoid screw 10 is formed on the outer peripheral surface of the lens barrel 10 using a split mold.
a, which is screwed into the helicoid screw 9b of the cylindrical rotary member 9 described above. Although not shown in a developed view, the helicoid screw 10a is also formed with three striped strips along the axial direction of the optical axis O, similarly to the case of the cylindrical rotary member 9 described above. However, no light-shielding wall such as the above-described light-shielding wall 9c is provided in those strips. Further, the lens barrel 10 includes a helicoid screw 10
a is formed in the cylindrical portion 1b provided in the shutter base plate 1, and the coil spring 1
1 is fitted.

The lens barrel 10 is linearly moved in the axial direction of the optical axis O by a guide means (not shown). The urging force of the coil spring 11 causes the cylindrical rotary member 9 to move. Together with the holding plate 7. Therefore, when focus adjustment is performed during shooting,
When the motor 5 is rotated by the number of rotations corresponding to the shooting distance, the rotation is transmitted to the gear 8 via the speed reduction mechanism,
Further, by rotating the cylindrical rotating member 9, the lens barrel 10 is extended linearly. When the photographing is completed, the motor 5 is rotated in the reverse direction, and the lens barrel 10 is returned to the original position.

In practice, an encoder or the like is mounted on the subject side of the shutter base plate 1 to control the number of rotations of the motor 5, or a shutter such as a motor for driving shutter blades. Are attached, but they are not shown because they are not directly related to the present invention. This unit is not provided with a cylindrical light-shielding wall centered on the optical axis O. That is, in a normal case, a cylindrical wall is usually provided so as to enclose all of the above-described configuration. The cylindrical light-shielding wall is often integrated with the shutter base plate 1. However, in the case of the present embodiment, since the size of the outer diameter of the unit is restricted,
It was impossible to provide such a cylindrical light-shielding wall.

Therefore, when such a unit is mounted on a camera, the cylindrical portion 12a is attached to the fixed lens frame 12 of the camera which is a part of the outer casing as shown in FIG. The cylindrical light-shielding wall is also used as described above. In addition, the attachment to the fixed lens frame 12 is such that a part of the support plate 4 faces the object side and is screwed from the object side of the fixed lens frame 12. However, in the case of such a configuration as shown in FIG. 1, the cylindrical portion 12a cannot be intimately adhered to the outer peripheral portion of the shutter base plate 1, and a gap of at least about 0.2 mm is generated. I will.

As described above, when the light shielding wall 9c is not formed at all in the strip of the cylindrical rotating member 9 and the lens barrel 10 as in the prior art, the focus adjustment is performed. When the cylindrical rotary member 9 stops at a predetermined rotational position, the two strips may face each other. Then, an optical path is formed there, for example,
The light that has entered the optical path as indicated by the arrow A shown in FIG. 1 passes between the cylindrical portion 12a and the outer peripheral portion of the shutter base plate 1 through the arrow B and the arrow B ', and the film surface side And the exposure state is affected.

In the initial position of the cylindrical rotary member 9, that is, at the position occupied when photographing is not performed, if the two strip belts are assembled to face each other, the film is loaded. In this case, even if the shutter blades are closed, the light that has entered by bypassing the blade chamber exposes the film. Therefore, in the conventional configuration, at the time of designing and assembling, it is necessary to take care that the two strips never face each other at any rotation stop position of the cylindrical rotating member 9. .

However, according to the present embodiment, since each light-shielding wall 9c is provided in each of the strips A of the cylindrical rotary member 9, even if both strips are opposed to each other, Most of the light is blocked, and there is no problem in practice. The light-shielding wall 9c is provided with a helicoid screw 9b of the cylindrical rotating member 9 and a helicoid screw 10a of the lens cylinder 10 regardless of the position of the lens barrel 10 moved.
Are always provided in the area where they are screwed together,
There is no difference in the light blocking effect. However, even in the case where the light shielding wall 9c is not provided as in the related art, the light is considerably attenuated from the arrow A to the arrow C, so that the light can be attenuated to a practically acceptable level. Then, the light shielding wall 9c is replaced with the helicoid screws 9b and 10a.
May be provided in an area where the screwing is temporarily not performed.

In this embodiment, the cylindrical rotating member 9 is used.
Each light-shielding wall 9c is provided in each of the strips A, but the number thereof is not limited, and any number of light-shielding walls 9c may be provided. Also, depending on the design, each of the strips A may be provided with a light shielding wall 9 respectively.
The c may not be provided, but may be provided only in some of the strips A. Further, in the present embodiment, the light blocking wall 9c is provided on the cylindrical rotating member 9, but it may be provided on the strip of the lens tube 10 as described above.
It may be provided on both the cylindrical rotating member 9 and the lens barrel 10. Further, in this embodiment, the light shielding wall 9c is provided independently, but at least one of the light shielding walls 9c may be continuous with the thread of the helicoid screw.

In this embodiment, the taking lens and the lens shutter are manufactured as a unit, and the unit is attached to the camera body. However, depending on the design, first, only the shutter unit is attached to the camera body. Then, a photographing lens may be attached thereto, and finally, an outer casing member such as the fixed lens frame 12 may be attached. Further, the present invention can be applied to a configuration including only a lens barrel, regardless of a shutter configuration, and can also be applied to a configuration of an interchangeable lens.

[0024]

As described above, the present invention is directed to a camera lens mirror in which a helicoid screw is formed so as to have a plurality of strips in a screwing region between a lens barrel and a cylindrical rotating member. In the torso, at least one of the strips is formed with a light-shielding wall along the thread of the helicoid screw, so that when the strip of the lens barrel and the strip of the cylindrical rotating member face each other. Thus, it is possible to effectively suppress the amount of light that is going to enter the interior from the space formed by them.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a developed view of the cylindrical rotary member shown in FIG.

FIG. 3 is a development view of a conventional cylindrical screw member on which a helicoid screw is formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a, 2a Opening 2 Auxiliary base plate 3 Blade chamber 4 Support plate 5 Motor 5a Output shaft 6,8 Gear 7 Press plate 8a, 8b, 9a Teeth 9 Cylindrical rotating member 9b, 10a Helicoid screw 9c Light shielding wall 10 Lens barrel 11 Coil spring 12 Fixed lens frame 12a Cylindrical part

Claims (2)

[Claims] 1. A cylindrical rotating member having a plurality of strips extending in the axial direction of an optical axis, having a helicoid screw formed on an inner peripheral surface thereof, and rotating around the optical axis, A helicoid screw which is screwed to the helicoid screw is formed on the outer peripheral surface so as to have a plurality of strips along the axial direction of, and a lens is mounted inside, and the optical axis is rotated by the rotation of the cylindrical rotating member. A lens barrel having a lens barrel that is operated linearly in the axial direction, wherein at least one light-shielding wall is formed along at least one of the missing strips along a thread of a helicoid screw. Characteristic lens barrel for camera. 2. The light-shielding wall according to claim 1, wherein the light-shielding wall is formed in a strip band portion in a region where the helicoid screw of the cylindrical rotating member and the helicoid screw of the lens barrel are always screwed together. Item 2. A lens barrel for a camera according to Item 1.