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US 5,398,091 AGranted
Method and apparatus for optimizing film flatness in a camera exposure gate
AssigneeEastman Kodak Company
InventorMarc Hershberger
Life of this patent
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AssigneeEastman Kodak Company
InventorMarc Hershberger
Estimating the term…
A method and apparatus suitable for use in a camera for alleviating the effects of film curl due to film core set in a film cartridge caused by aging and/or elevated temperatures. Curl in a film strip stored in a cartridge must be flattened out in the exposure space gate of the camera so that the camera is able to optimally focus an image of an object on the entire image receiving surface of the film within the exposure space gate of the camera. Photographic film wound tightly into film cartridges and stored for a period of time develops a core set approaching the diameter at which it was maintained such that film frames closest to the core have higher degrees of curl than those frames farther away from the cartridge core. Ambient temperature and humidity also contribute to the degree of curl at the time an exposure is made. In order to achieve optimum film flatness in a conventional space gate (i.e., platen, rails), a wider gap is optimum for higher curl and a narrow gap is optimum for lower curl. Adjustment of the gap in the space gate may be accomplished by mechanically detecting the diameter of the film wound about the take-up reel or may be electronically approximated by processing signals reflecting the manufactured date of the film cartridge, the total number of potential image frames of the film in the cartridge, and current exposure frame number to estimate the amount of core set and adjust the space gap accordingly in an automatic exposure control camera. Optionally, the ambient temperature and/or humidity may also be sensed and used to derive the space gate gap. Moreover, the focus of the camera lens may be adjusted along with the space gate gap.
In a camera of the type having a lens assembly, a shutter mechanism and a film advance mechanism for advancing film past an exposure space gate and between a film cartridge and take-up reel, wherein the exposure space gate includes a pressure plate for exerting pressure against the back of the film to press it flat against the exposure space gate rails to thereby define an exposure frame, the improvement in apparatus for adjusting the exposure space gate gap between the pressure plate and space gate rails to compensate for core set film curl comprising:
In a camera of the type having a lens assembly, a shutter mechanism and a film advance mechanism for advancing film past an exposure space gate and between a film cartridge and take-up reel, wherein the exposure space gate includes a pressure plate for exerting pressure against the back of the film to stretch it flat against the exposure space gate rails to thereby define an exposure frame, the improved method for adjusting the exposure space gate gap between the pressure plate and space gate rails to compensate for core set film curl comprising the steps of:
In a camera of the type having a lens assembly, a shutter mechanism and a film advance mechanism for advancing film past an exposure space gate and between a film cartridge and take-up reel, wherein the exposure space gate includes a pressure plate for exerting pressure against the back of the film to press it flat against the exposure space gate rails to thereby define an exposure frame, the improvement in apparatus for adjusting the exposure space gate gap between the pressure plate and space gate rails to compensate for core set film curl comprising:
In a camera of the type having a lens assembly, a shutter mechanism and a film advance mechanism for advancing film past an exposure space gate and between a film cartridge and take-up reel, wherein the exposure space gate includes a pressure plate for exerting pressure against the back of the film to press it flat against the exposure space gate rails to thereby define an exposure frame, an improved method for adjusting the exposure space gate gap between the pressure plate and space gate rails to compensate for core set film curl comprising the steps of:
Dependencies are inferred from the claim text.