Cam follower and lens barrel

Details Cam follower and lens barrel Cam follower and lens barrel

1999-10-20

2001-03-06

Mack, Ricky (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S694000

Reexamination Certificate

active

06198578

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the structure of a lens barrel having lens frames that are driven to advance or withdraw via cam followers.
2. Description of the Related Art
Conventional lens barrels have lens frames that can be advanced or withdrawn. A mechanism made by combining a cam groove and a cam follower is generally utilized for driving the cylindrical lens frames to advance or withdraw them. The cam groove runs obliquely to an optical axis, and the cam follower is engaged with the cam groove so that the cam follower can slide freely.
A structure enabling the whole slider surface of the cam follower to slide on a cam slide surface has been adopted as the structure of the cam follower that engages with the cam groove and slides thereon.
Moreover, a structure having the straight shaft of the cam follower press-fitted into a locking hole in a lens frame and thus having the cam follower to fixed to the lens frame has been adopted as the structure of the cam follower to be fixed to the lens frame.
In a conventional lens barrel to which the cam and cam follower is adapted, lens frames are small-sized in compliance with a recent demand for a compact and lightweight camera. Moreover, the lens frames tend to be thinner.
The lens frames themselves are therefore likely to deform. As far as the foregoing conventional structure enabling the cam follower to slide is concerned, when force is applied to the cam follower, the lens frame may be deformed and the cam and cam follower may be disengaged from each other.
Moreover, since the dimension of the shaft of the cam follower press-fitted into the lens frame is very small, if force is applied to the cam follower, there arises a fear that the press-fitted shaft may come off or become unstable. Moreover, using an adhesive to fix the shaft is unfavorable in terms of a manufacturing process or product management. Adhesives are therefore hardly used.
SUMMARY OF THE INVENTION
The present invention attempts to overcome the foregoing drawbacks. An object of the present invention is to provide a lens barrel having a frame advancing and withdrawing mechanism to which a cam follower is adapted, and capable of being smoothly driven to advance or withdraw. The lens barrel is characterized in that the portion of the cam follower engaged with the lens barrel will hardly come off, the cam follower fixed to a lens frame will hardly come out, and lens frames can be designed compactly.
According to one aspect of the present invention, there is provided a lens barrel having a first frame, a second frame, and a cam follower. The first frame has a cam groove cut therein. The second frame moves relative to the first frame. The cam follower has a slider surface that slides in contact with a cam surface of the cam groove, and has an edge formed on the slider surface. The shaft of the cam follower has a circumferential edge formed on the circumference of the shaft. The shaft is fitted into a hole bored in the second frame, whereby the cam follower is fixed to the second frame.
Moreover, according to another aspect of the present invention, there is provided a lens barrel having a first frame, and a second frame, and a cam follower. The first frame has a cam. The second frame moves relative to the first frame. The cam follower is fixed to the second frame, and has a slider surface that slides in contact with a cam surface of the cam groove, and a circumferential edge formed as a margin of the slider surface. The slider surface of the cam follower slides on the cam, whereby the second frame makes a relative movement.
Moreover, according to yet another aspect of the present invention, there is provided a lens barrel having one frame member, the other frame member, and a cam follower. The one frame member has a cam. The other frame member moves relative to the one frame member. The cam follower has a fitting shaft with which the cam follower is fitted in the other frame member, and a slider surface that slides on the cam. The cam follower has an edge formed on the circumferential surface of the shaft thereof. The shaft is press-fitted into a hole bored in the other frame member.
Other features of the present invention and advantages thereof will be fully apparent from the description below.


REFERENCES:
patent: 4707083 (1987-11-01), Iizuka et al.
patent: 5721645 (1998-02-01), Iwasaki et al.

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