US Patent 7400378 Dual sprocket contact motion picture film printer

A dual sprocket contact motion picture film printer maintains film steadiness when running a film negative in contact with an unexposed raw stock film by tensioning perforations along one film side against sprocket teeth of a full fitting sprocket and a shrinkage sprocket on the other side. The films pass through a fluid chamber before passing through a printer aperture and a vacuum pressure applied from one side of the chamber tensions the negative against the sprocket teeth while a positive fluid pressure applied from an opposite side tensions the raw stock against the sprocket. The films are self-aligned by the fluid forces maintaining equal tension on both sides of each film strip as the films pass the aperture of the film printer.