1. Field of the Invention
The present invention relates to a camera, and more particularly to a camera using a film cartridge equipped with a means for indicating an exposed state of a film.
2. Related Art Statement
A photographic film is generally handled in a state of being housed within a film cartridge which is a simple cartridge with a light screening or shielding function for the purpose of its protection against exposure in mounting and removing in and from a camera or during storage and conveyance. In addition, the decision on whether a film is in a non-exposed condition or in an exposure-completed condition is made by checking whether or not a tip portion of the film is drawn out from a film-drawing opening of the film cartridge.
U.S. Pat. Nos. 4,423,943, 4,998,123, and 5,296,887 disclose a new type of cartridge different from the prior types, where a film is completely or entirely accommodated therein regardless of being in a non-exposed condition, a partially exposed condition or an exposure-completed condition. In this instance, the film-mounting into a camera is automatically made in such a manner that a fork and a spool geared therewith are rotatively driven with a motor, with the result that the carelessness of the user can cause double exposure to the film.
On the other hand, U.S. Pat. No. 4,994,828 or Japanese Unexamined Patent Publication No. 6-301106 has proposed an approach to eliminate this problem, where a camera is provided with a sensor means cooperating with an exposure-state indicating device so that the insertion of the film cartridge into a film compartment (cartridge compartment) is inhibited when the exposure-state indicating device assumes an exposure-completed condition. In addition, as exemplified by Japanese Unexamined Patent Publication No. 4-90530, there has been proposed an ejecting means which pushes out a film cartridge by a biasing means such as a spring in response to a film cartridge ejecting operation.
There is a problem which arises with the provision of this sensor means, however, in that a side wall of the film cartridge suffers damages and the mounting of the film cartridge requires a larger force due to the resulting occurrence of a friction between the sensor means and the film cartridge, for that the sensor means is generally biased by a spring to protrude into the film compartment and made to retreat from the cartridge sitting position and then to come into contact with a side wall of the film cartridge when a non-exposed film cartridge is mounted therein. In addition, when the film cartridge is taken out from the film compartment after the completion of photography, difficulty is experienced to easily remove the film cartridge from the film compartment due to the frictional force taking place between the sensor means and the film cartridge.
What is worse, in the case of the apparatus disclosed by the aforesaid Japanese Unexamined Patent Publication No. 6-301106, if the film cartridge once mounted therein is taken out halfway after the photography completion and then again mounted immediately before its insertion-inhibiting function begins to work, the camera operates normally to result in double exposure.