Photocopying – Contact printing – Machine
Patent
1994-12-19
1997-04-08
Pendegrass, Joan H.
Photocopying
Contact printing
Machine
355 84, G03B 2704
Patent
active
056193068
ABSTRACT:
Photographic films, such as X-rays, are duplicated by exposing an unexposed copy film in the presence of an intimately overlying developed film to be copied. The device exposure station has a pair of rollers at the entrance to drive the film pair and to remove from the interface between the films trapped air that would compromise the accuracy of resolution and contrast of the copy. Another pair of rollers at the outlet from the exposure station cooperates with the roller pair at the exposure station inlet to maintain the film pair within the exposure station in a planar orientation to avoid curvature which is another principal source of compromised resolution in film copies. The source of illumination for copy film exposure is, preferably, a fluorescent tube that generates emissions that are approximately matched to the wave length response of the unexposed copy film and has a length such that each end is disposed beyond the portion of the exposure station confronting a film pair so that only the tube portion intermediate the heating elements at the tube ends, where emission is most uniform, confronts the film being exposed. The film pair is driven through the apparatus by a stepper motor controlled by a microprocessor which enables the average film pair speed (and thus the exposure time) to be selected from a range of incremented values contained in an addressable controller memory location. The sequence of incremented step rate values can be changed by addressing another addressable block of values in the controller memory.
REFERENCES:
patent: 3953125 (1976-04-01), Bost
patent: 4891664 (1990-01-01), Kanai
patent: 4926215 (1990-05-01), Rank, Jr.
patent: 5073792 (1991-12-01), Paccagnella
Baxter Duane W.
Hamburgen Arthur
Wanek Donald J.
Lahtinen Robert W.
Pendegrass Joan H.
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