Lens barrel

Details Lens barrel Lens barrel

2000-06-22

2001-06-12

Mathews, Alan A. (Department: 2851)

Photography

Having variable focal length of camera objective

Power zoom

C396S072000, C359S823000

Reexamination Certificate

active

06246834

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an angular lens barrel used in an optical device such as a camera.
2. Related Background Art
Conventionally, as lens barrels in optical devices such as cameras, lens barrels having rectangular cross sections are known as disclosed in Japanese Patent Utility Model No. 2548509 and Japanese Patent Laid-Open No. 9-222550. These lens barrels cannot extend and retract in the same manner as in a cylindrical lens barrel that extends and retracts upon being rotated by a helicoid mechanism. For this reason, a link mechanism is placed in a lens barrel, and the lens barrel extends and retracts along the optical axis upon extension/contraction of the link mechanism.
According to the lens barrel disclosed in each reference described above, the link mechanism serves not only as a driving mechanism for applying extending force and retracting force to the lens barrel but also as a guide mechanism for moving the lens barrel along the optical axis. For this reason, the link mechanism needs to have certain rigidity, and link pieces and the like making up the link mechanism must be thick. As a consequence, the link mechanism becomes considerably thick as a whole, resulting in an increase in the size of the lens barrel
In addition, to make the link mechanism serve as a guide mechanism, the link mechanism and associated peripheral structures must be accurately formed.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above technical problems, and has as its object to provide a lens barrel which can accurately extend and retract with a simple structure without increasing its size.
In order to achieve the above object, according to the present invention, there is provided a lens barrel used in an optical system of an optical device, comprising a first barrel which can move along an optical axis of the optical system, accommodates a guide shaft directed to the optical axis, and has an angular cross section, and a second barrel which has a cross-sectional shape formed by partly notching an angular shape, has a bearing portion behind the notched portion through which the guide shaft extends, and can extend and retract with respect to the first barrel.
According to the present invention, the second barrel can be accurately extended along the optical axis of the optical system by guiding it along the guide shaft. In addition, the formation of the notched portion in the second barrel allows efficient use of the internal space of the first barrel in which the guide shaft is placed, thereby housing the second barrel therein. This makes it possible to accurately extend and retract the second barrel without increasing the size of the first barrel.


REFERENCES:
patent: 4958178 (1990-09-01), Yoshida
patent: 5689739 (1997-11-01), Yoshida et al.
patent: 5-249362 (1993-09-01), None
patent: 2548509 (1997-05-01), None

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