Patent GB-565611-A (GB)
Title: Improvements relating to apparatus for processing photographic films
IPC: G03D3/12
Filed: 1943-05-14
Abstract: 565,611. Photographic processing apparatus. DUGUID, R. J. May 14, 1943, No. 7746. [Class 98 (ii)] Apparatus of the type in which photographic films in comparatively long lengths are traversed in extended form through a container within which the processing operation (e.g. developing, fixing, washing, or bleaching) is effected, is provided with means for traversing the film continuously through the treatment chamber first in a helical path proceeding in a direction from one side or end of the chamber towards the other and then in a helical path proceeding in the reverse direction. The apparatus may comprise an endless carrier (e.g. an endless band, belt, or chain) arranged to be traversed in succession in two oppositely directed parallel helical paths and means for connecting the film to the carrier surface for movement therewith. As shown, a framework 11 for insertion in a tank has two pairs of rollers 13, 14 (the front pair) and 15, 16 (the back pair), and the endless band 12 is wound helically from one side of the frame around the top roller 14 and bottom roller 13 to the opposite side, where it is taken round the bottom roller 15 and wound helically in the reverse direction around the back pair of rollers to the original side, where it is taken over the top roller 14. The top rollers 14, 16 carry gear wheels meshing with a pinion 19 adapted to be rotated either by a hand crank 20 or by reduction gearing 21 from an electric motor. The rollers are provided with guide flanges, or alternatively guides are provided on the frame 11. The roll of film 23, on a spool, magazine, or other container, is mounted on or held against the end of a shaft 24 carried on a bracket 25. The leading end 27 of the film is taken through the light-trapped opening 28 and is attached to the band by a collar 29 slidable on the band and provided with a catch so arranged that when pulled in the direction opposite to that in which the band is travelling it will grip the band, e.g. it may engage holes or corrugations therein. Alternatively, a stop may be arranged on the band. The end 27 is attached to the collar 29 through a spring tensioning device 30 (which may be a strip of elastic material) which may have a second collar to which the end of the film is attached. The shaft 24 may have a spring brake or like retarding device to ensure that the tensioning device 30 is extended to the maximum extent. The hinged lid 31 forms a light-tight enclosure for the film so that the apparatus may be used for daylight loading. To indicate when the film has been fully wound on, the collar 29 may carry a projection arranged to operate a bell or to raise a rod operating through the top panel 26 to give a visual signal. Alternatively the projection may close an electric contact to illuminate a lamp. After the film has been fully wound on, the trailing end is attached to the collar 29, so that the band is covered by the film with the tensioning device between the two ends of the film. The tank is provided at the top with a light-trapped inlet for the treating solution and at the bottom with a capclosed outlet or tap through which the solution may be removed. A further or alternative inlet may be provided in the top panel 26. Only a small quantity of solution at the bottom of the tank is needed. After processing, the film is rewound on the spool. In a modification, four pairs of rollers are provided. For short lengths of film, there may be but two convolutions of the endless band on each pair of rollers.