GB1370598A - Photographic film products and methods of manufacturing such products - Google Patents

Abstract

1370598 Film units POLAROID CORP 24 April 1973 [5 May 1972 6 Nov 1972] 19295/73 Heading G2X In a film unit which includes a layer of photosensitive material between a pair of superposed sheets which is processed in situ by spreading a processing liquid between the sheets, these are spaced apart along the lateral margins by tapered spacers, to assist in obtaining a more uniform spread of the liquid. The unit is of the type in which a supply of processing liquid is provided in a pod attached to one of the sheets, and which is ruptured by passing the unit between pressure rollers which then spread the liquid between the sheets. The liquid tends to vary in thickness from a minimum near the leading edge to a maximum at the trailing edge. By providing a tapered spacer which varies from a maximum at the leading edge to a minimum at the trailing edge, this has a counter action on the varyingthickness of the liquid, so tending to produce a more uniform spread. The tapered spacer is preferably formed as a number of separate layers, as shown in Fig. 6, and is preferably applied to the polyester base sheet 48 by a gravure process. A gravure roller is prepared having cells 66 which vary progressively in depth across the width of the roller. Fig. 7 shows three such rollers, so that three sheets may be made simultaneously. The rollers 62 dip into a supply of coating liquid 70, and the sheet 48 is passed between rollers 62 and a pressure roller 64.