Document Type and Number:
Japanese Patent JPS50151147
Kind Code:
A
Abstract:
A film cartridge loaded with a roll of motion picture film having a magnetic stripe on one surface of the film is subject to shaking or impacts during handling of the cartridge which results in displacement of some convolutions of the film in a direction parallel to the axis of the film roll, especially when the film has first clocksprung in a radial direction. When this occurs, friction between the displaced convolution and the adjacent convolutions of the film effectively prevents return of the stepped convolution to its original position. Subsequently, when film is to be pulled from the supply roll during operation of a camera in which the cartridge is positioned, the stepped convolutions can contact a wall of the cartridge defining the supply chamber in the cartridge and produce a frictional force that opposes normal unwinding of the film. This can result in improperly exposed film. In order to avoid the undesirable results from stepped film, the film supply chamber is expanded in a direction parallel to the axis of the roll. This expansion of the supply chamber is effected by a pusher member which is urged against a wall of the supply chamber to cause that wall to flex in an outward direction, thereby obtaining some additional space within the supply chamber to permit substantially free rotation of the film roll even if it has become stepped. Movement of the pusher member to a position for flexing the cartridge wall is effected by a rodlike member comprising part of a disengageable anti-backup mechanism. The rod can be moved to a position for moving the pusher member in response to proper insertion of the cartridge into an operative position in the camera.
Application Number:
JP5199675A
Publication Date:
December 04, 1975
Filing Date:
April 28, 1975
Export Citation:
International Classes:
G03B19/18; G03B17/26; G03B31/00; (IPC1-7): G03B23/02; G03B31/02