Photography – Having variable focal length of camera objective – Having direct viewfinder
Reexamination Certificate
1998-12-02
2003-05-27
Mahoney, Christopher (Department: 2851)
Photography
Having variable focal length of camera objective
Having direct viewfinder
C396S373000, C396S379000
Reexamination Certificate
active
06571059
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a camera, particularly to a driving system for driving a photographing optical system and a finder optical system (with variable magnifications) of a camera in which the photographing optical system and the finder optical system exist independently from each other.
2. Description of the Related Art
For a long time, a camera for taking a picture has usually been an optical device in which a photographing optical system and a finder optical system exist independently from each other. In detail, a commonly used camera device is designed in a manner such that its photographing optical system and its finder optical system are capable of changing in their focal distances.
On the other hand, there has long been a demand that a camera be made compact in size, but there is another demand that a camera's photographing optical system be made to have a long focal distance and a high variable magnification. The above two sorts of demands have been remarkably satisfied in a camera of a kind which uses a compact type film such as IX240 film. However, with such kind of compact camera, it has been found that an interval distance between an optical axis of a photographing optical system and an optical axis of a finder optical system has become shorter than before, and that both the photographing optical system and the finder optical system have longer focal distances and higher variable magnifications.
Since an interval distance between the optical axis of a photographing optical system and the optical axis of a finder optical system has become shorter, and since both the photographing optical system and the finder optical system have longer focal distances and higher variable magnifications, an observation image of the finder optical system will be obstructed by a lens-barrel which holds the photographing optical system, causing an undesirable phenomenon called “eclipse”.
In order to solve the above problem, Japanese Unexamined Patent Publication No.7-261243 has suggested a technical solution for prohibiting the eclipse phenomenon by improving some related optical systems involved in a camera.
Further, Japanese Unexamined Patent Publication No.9-138464 has suggested another technical solution for prohibiting the eclipse phenomenon by utilizing a TTL system which can divide an optical path at middle of a camera lens. In addition, Japanese Unexamined Patent Publication No.9-197487 has suggested a further technical solution for prohibiting the eclipse phenomenon by projecting the finder optical system into a different position during a photographing operation.
However, solving an eclipse phenomenon as discussed above has been proved to be not so easy. For instance, the technical solution suggested by Japanese Unexamined Patent Publication No.7-261243 has been proved to be not suitable for use in a camera which has a further higher variable magnification. The technical solution (utilizing a TTL system) suggested by Japanese Unexamined Patent Publication No.9-138464 and the technical solution (projecting the finder optical system into a different position during a photographing operation) suggested by Japanese Unexamined Patent Publication No.9-197487, have been proved to be not suitable for general use because of their complex structures and their large size.
SUMMARY OF THE INVENTION
In view of the above problems associated with the above discussed prior art, it is an object of the present invention to provide an improved camera which is capable of controlling a stop position of a camera lens, so that an observation image of a finder optical system will not have an eclipse phenomenon which would otherwise be caused due to a camera lens-barrel, thereby enabling the camera to have an improved performance and enabling a user to have an improved feeling when using the camera.
As a brief summary, an improved camera made according to the present invention, has a photographing optical system and a finder optical system existing independently from each other, said camera comprising a driving circuit for respectively driving the photographing optical system and the finder optical system, and a control circuit for controlling the photographing optical system in a manner such that the finder optical system will not be obstructed by the photographing optical system.
Other objects and advantages of the present invention will become clearly understood from the following detailed descriptions.
As related above, the present invention provides a camera which has a photographing optical system and a finder optical system existing independently from each other. With the use of the present invention, an optical design can be made easier than before for a compact camera which is compact in size and has an photographing optical system with a high magnification. Meanwhile, the present invention makes it possible to provide a camera capable of easily prohibiting an eclipse phenomenon in an observation image of the finder optical system, so as to prevent the observation image from being obstructed by the photographing optical system.
REFERENCES:
patent: 4964686 (1990-10-01), Kato
patent: 5055868 (1991-10-01), Itoh et al.
patent: 5083146 (1992-01-01), Ueda
patent: 5606383 (1997-02-01), Daitoku et al.
patent: 5634147 (1997-05-01), Machida
patent: 5692227 (1997-11-01), Yokota et al.
patent: 5848302 (1998-12-01), Machida
patent: 02234111 (1990-09-01), None
patent: 04053938 (1992-02-01), None
patent: 07261243 (1995-10-01), None
patent: 09138464 (1997-05-01), None
patent: 09197487 (1997-07-01), None
Kodama Shinichi
Sugita Yukihiko
Mahoney Christopher
Olympus Optical Co., LTD
Volpe and Koenig P.C.
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