This invention relates to film drive assemblies for photographic printers and, more particularly, to methods for attachment of film drive assemblies to photographic printers.
Commercial photographic processing laboratory require the capability of making vast numbers of photographic prints from equally large numbers of photographic negatives. The photographic negatives are typically handled in long roll form, and are processed in photographic printers by mounting the long roll of negative film on mechanized film drives. The photographic printers may operate in both automated and semi-automated environments.
Most film drives for use with these photographic printers are either electrically or pneumatically powered. A continuous roll of exposed and developed photographic film is mounted on the feed spool of the film drive and routed across the optical stage of the photographic printer. Individual negative frames are sequentially positioned at the optical stage of the photographic printer by operation of the drive components of the film drive so that one or more photographic prints can be made from each frame, under either operator or machine control. Finally, the film is collected on a film takeup spool of the film drive.
Because photographic film is manufactured in a variety of different widths, a film drive needs to be capable of variably positioning the film in relation to the photographic printer so that the longitudinal center line of the various widths of photographic film can be positioned to correspond with the optical center of the photographic printer. And because each frame of a roll of photographic film requires individual cropping, a film drive further must be capable of variably positioning each frame of a roll of film of a given width.
A number of devices have been developed and utilized, with limited success, to provide the capacity for variably positioning the film in relation to the printer. In U.S. patent application Ser No. 359,852, filed May 31, 1989, now U.S. Pat. No. 5,097,292 issued Mar. 17, 1992 an apparatus is disclosed consisting essentially of two nested brackets, one affixed to the printer work surface and the second slidably affixed to the first. An alternative type currently used in printers manufactured by Lucht Engineering of Minneapolis, Minn., permits the entire drive assembly to slide longitudinally across a limited portion of the printer work station top surface. Both of these devices utilize electronic position sensing switches to relocate the film center line. This arrangement has not been entirely satisfactory since it requires sophisticated Hall effect magnetic sensor technology to function with a degree of reliability necessary in a commercial setting. Additionally, removal of the drive mechanism is frequently time consuming and labor intensive. The present invention addresses these problems.