PROCEDE ET DISPOSITIF POUR EVITER LE VOILAGE DE PARTIES DE FILMS PHOTOGRAPHIQUES NON EXPOSEES

An apparatus and methods for producing a transmission barrier for inhibiting propagation of light into still unimaged transparent portions of microfiche recording system intermediate film strips by light-piping action are described. The barrier serves to optically isolate the subsequently-to-be-imaged still unexposed portion of the film strip in a dispensing film head from the illumination used to transfer the previously developed image on the exposed portion of the strip onto a permanent recording medium, such as a microfiche film card. In one exemplary form of the invention, the barrier regions are photographically produced dark bands or lines between the longitudinally spaced areas of the film strip to be imaged. These bands or lines are preferably created as latent images during the initial exposure of the intermediate film and subsequently developed at the same time as the record image. Alternative embodiments include placing bands or lines of light absorbing material on the film strip or by serrating or otherwise locally deforming the intermediate film strip to produce the barrier regions, the serrations serving to spoil total internal reflection in the film. Long term fogging of the film by normal ambient light is dealt with by providing an automatic film payout feature. Particular applications to archival microfiche systems involving the intermediate film strip carrying a transferable image are described. An apparatus for using pre-formed barriers on the film strip to regulate film advance is described.