Photography – Having variable focal length of camera objective
Reexamination Certificate
2003-03-03
2004-03-16
Perkey, W. B. (Department: 2851)
Photography
Having variable focal length of camera objective
C359S696000
Reexamination Certificate
active
06707993
ABSTRACT:
This application is based upon application No. 2002-349843 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a lens barrel, and particularly relates to the lens barrel which is suitable for a multistage zoom lens (or multiple-step zoom lens).
2. Description of the Related Art
Conventionally, there have been proposed a variety of lens barrels each of which is of a type in which the lens barrel can be projected from its camera body. For examples, each of Japanese Laid-Open Patent Publication No. 2000-66081 and Japanese Laid-Open Patent Publication No. 2001-183563 discloses a lens barrel which is of the type in which the lens barrel can be projected from its camera body by two steps or by two stages. On the other hand, U.S. Pat. No. 6,052,535 discloses a lens barrel which is of the type in which the lens barrel can be projected from its camera body by three steps or by three stages.
The conventional zoom lens barrel which projects from its camera body by two steps, generally, has a straight-moving member which is guided linearly by a fixed barrel (or a stationary barrel), and it has a first rotation member which is positioned radially outside the straight-moving member, which moves integrally therewith in a direction of its optical axis, and which is rotatable relative to the straight-moving member. In addition, the zoom lens barrel has a second rotation member which is positioned radially inside the straight-moving member, which moves relative to the straight-moving member in the direction of the optical axis, and which rotates and interlocks with the first rotation member, where a rotation interlocking piece mounted on the second rotation member is inserted inside an elongate hole formed on the straight-moving member.
According to the conventional zoom lens barrel, however, many components or elements superimpose one over another in its radial direction. Therefore, it is difficult to make the zoom lens barrel small or compact. Also, because the straight-moving member has a low rigidity owing to the presence of the elongate hole, it is difficult to realize a high accuracy for driving and a high anti-shock nature (or a high shock-resistant nature). Also, because there is need of adding a light blocking member (or a light shielding member) in the mechanism, it is difficult to avoid a high cost thereof. Also, in a case of developing the mechanism of the projection of the zoom lens barrel by two steps into a mechanism of the projection of the zoom lens barrel by three steps, there arises a problem of how the straight-moving interlocking mechanism for limiting its rotation should be constructed.
Also, the multistage projection tripe of lens barrel has a straight-moving member for limiting the rotation thereof, and it has a rotation member which rotates relative to the straight-moving member. More specifically, in the mechanism, there are provided a plurality of pairs, each of which is composed of the straight-moving member and the rotation member, and each of which moves integrally in the direction of the optical axis. Between the adjacent pairs, the straight-moving members are interlocked with each other in terms of their straight movement, and the rotation members are interlocked with each other in terms of their rotation. The pairs move relative to each other in the direction of the optical axis on the basis of mutual engagement between the straight-moving member of one of the adjacent pairs and the straight-moving member of the other thereof, so that the lens barrel can project (or expand) and contract (or retract).
The conventional lens barrel having the mechanism of projection by more than two steps, has a construction in which there is mounted the straight-moving member between the front and rear rotation members.
For example, in a case of a mechanism in which the rotation member of one of the pairs is connected to the straight-moving member of the other of the pairs by screw so that the one of the pairs projects from the other of the pairs in which the rotation member is arranged radialy and outwardly of the straight-moving member, there is need of forming a space extending spirally (or helically) on the straight-moving member of the other of the pairs in order to transmit rotation between the rotation member of the one of the pairs and the rotation member of the other thereof.
According to the mechanism, the rigidity of the straight-moving member of the other of the pairs is relatively lower owing to the spiral space formed therein. Therefore, for example, considering the exertion of any excessive power on the lens barrel in the axial direction, not only there exists a limitation to reduction of dimension of the straight-moving member of the other of the pairs in the radial direction, but also there exists a limitation to increase, for increasing the accuracy in control, of rotational angle of the rotation member. Furthermore, in order to prevent light from entering the spiral space of the straight-moving member of the other of the pairs, the light blocking mechanism (or light shielding mechanism) can not help but be complicated in structure.
Accordingly, there has not yet been provided a lens barrel, with a low cost and a high rigidity thereof, having a mechanism of projection thereof by more than two steps, in which the lens barrel is compact or small-sized.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a lens barrel which can project and retract by taking more than two steps or stages, in which the lens barrel can be downsized or can be made compact.
In accomplishing this and other objects of the present invention, according to one aspect thereof, there is provided a lens barrel comprising: a fixed lens barrel member; a first straight-moving member for guiding a first lens barrel member movably in an axial direction of the fixed lens barrel member; a second straight-moving member for guiding a second lens barrel member movably in the axial direction of the fixed lens barrel member, in which the second straight-moving member is provided generally on a same circle or circumference, in a plane perpendicular to the axial direction thereof, as that of the first straight-moving member; and a third straight-moving member for guiding a third lens barrel member movably in the axial direction of the fixed lens barrel member, in which the third straight-moving member is provided generally on the same circle or circumference, in the plane perpendicular to the axial direction thereof, as that of the first straight-moving member.
In the mechanism, a first pair composed of the first straight-moving member and the first lens barrel member as a first step (or as a first stage, or as a first level) with respect to the fixed lens barrel member, a second pair composed of the second straight-moving member and the second lens barrel member as a second step (or as a second stage, or as a second level) therewith, and a third pair composed of the third straight-moving member and the third lens barrel member as a third step (or as a third stage, or as a third level) therewith, can project from each other with respect to the fixed lens barrel. According to the mechanism, the first straight-moving member, the second straight-moving member and the third straight-moving member, are provided or arranged generally on the same circumference, or circle, in the plane perpendicular to the axial direction of the fixed lens barrel. Consequently, with the mechanism, the thickness of the first straight-moving member, the thickness of the second straight-moving member and the thickness of the third straight-moving member, do not accumulate in a direction of radius of the lens barrel; therefore, the lens barrel which can project and retract by taking more than two steps and which can be made compact in size, is provided.
As an embodiment, a lens barrel member of at least one of the first pair, the second pair, and the third pair, is relatively rotata
Kohno Hisanori
Mitani Yoshifumi
Uno Tetsuya
McDermott & Will & Emery
Minolta Co. , Ltd.
Perkey W. B.
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