Photocomposing apparatus and method

Abstract

Photosensitive sheet handling apparatus and method for phototypesetters. Accurate control of the lateral positioning of the sheet (i.e., film) is provided by the use of tapered drive rolls. The apparatus includes an input cassette, a film input drive assembly comprised of tapered pinch rollers and a lateral film edge locating stop, a slightly tapered vacuum film drive drum having a collar or flange on one side in accurate alignment with the edge locating stop of the pinch rollers, a motor operated output drive assembly also comprised of tapered pinch rollers and a film edge locating stop in accurate alignment with the drum flange, and a periodically operated film winding mechanism located within an output cassette. The tapered rolls urge one edge of the film against the flange of the drum and stops of the pinch rollers to maintain accurate alignment. Chambers are provided for receiving loops of film at the input and output sides of the drum. The film moves forwardly for leading, and moves in the reverse direction for reverse leading. During the reverse motion, film is withdrawn from one of the loops while another loop is formed to take up the film. This avoids the scratching and wear which otherwise would occur by repeatedly passing the film through the pinch rollers. The film winding mechanism in the output cassette winds the film under tension, but periodically relieves the tension in order to prevent the film from jamming in the output cassette.