Photography – Camera detail – Detachable or removable film holder unit
Reexamination Certificate
1996-11-19
2001-01-30
Gray, David M. (Department: 2851)
Photography
Camera detail
Detachable or removable film holder unit
C396S515000, C396S538000
Reexamination Certificate
active
06179494
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a camera using a film cartridge provided with rotatable display means rotatable with a supply spool in the film cartridge and displaying by its rotated position whether the film is unused or used, and rotation restraining means for preventing said supply spool from being rotated except during the loading with the camera.
2. Related Background Art
A film cartridge designed such that whether the film therein is unused or used is displayed by a member movable in response to the rotation of a supply spool in the film cartridge is proposed in Japanese Laid-Open Patent Application No. 2-114248.
In the above-described example of the prior art, it is necessary that a member for locking the rotation of the supply spool be provided in the film cartridge to prevent the supply spool from being inadvertently rotated to thereby change the display, that is, to prevent the occurrence of the deviation of the relative position of the member movable with the supply spool and (the outer cover of) the film cartridge, when the film cartridge is removed from the camera and is a single piece.
Accordingly, to load the camera with the film cartridge and start the feeding of the film, said lock member must be released.
However, the film twines around the supply spool and therefore, tension is created in the direction of rotation of the supply spool and thus, the supply spool is rotated upon unlocking and the relative position of the member movable with the supply spool and (the outer cover of) the film cartridge is changed, and this has led to the possibility of displaying wrong information. Particularly when the information as to whether the film is unused one or used one is changed by mistake, it will result in a serious error such as double exposure.
SUMMARY OF THE INVENTION
It is an aspect of the present invention to provide, in view of the above-noted point, a camera in which the phenomenon that the display of the state of use of film is erroneously read and the film is double-exposed can be prevented.
Also, when loading a camera with a film cartridge, the fork of the camera sometimes is not in complete mesh engagement with a supply spool and this may cause slippage between the fork and the supply spool, which is thus rotated. Also, when removing the film cartridge from the camera, the stopped position of the supply in the film cartridge is controlled by the rotation of the fork and particularly, during the rewinding of film, tension remains in the film and therefore, in the case of such structure that lock works when the film cartridge is taken out with the cartridge lid of the camera opened, the fork also comes out at the same time, and this has led to a result that with a delicate deviation of timing, the position of the supply spool is changed by the tension of the film rolled in.
It is an another aspect of the present invention to provide, in view of the above-noted point, a camera in which the phenomenon that the display of the state of use of film in a film cartridge becomes wrong by deviating during the loading of the camera with the film cartridge or during the removal of the film cartridge from the camera can be prevented.
REFERENCES:
patent: 3894796 (1975-07-01), Cook et al.
patent: 4834306 (1989-05-01), Robertson et al.
patent: 4994828 (1991-02-01), Smart
patent: 5030978 (1991-07-01), Stoneham et al.
patent: 5047794 (1991-09-01), Pagano et al.
patent: 5049912 (1991-09-01), Pagano et al.
patent: 5115268 (1992-05-01), Kitagawa et al.
patent: 5475454 (1995-12-01), Ezawa
patent: 5483310 (1996-01-01), Tanii et al.
patent: 2-114248 (1990-04-01), None
patent: 3-67535 (1991-03-01), None
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Gray David M.
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