Patent GB-191414901-A (GB)
Title: Photographic Printing and Apparatus therefor.
Inventor: THORNTON JOHN EDWARD
IPC: G03B27/08
Filed: 1914-06-23
Granted: 1915-06-22
Abstract: 14,901. Thornton, J. E. June 23. Printing - apparatus, step-and-repeat. - Relates to the printing of three - colour and other kinematograph films, or other continuous strips such as post-card paper, coated with an emulsion of low sensitiveness, such as those prepared with bichromates or iron salts. A large number of pictures are exposed simultaneously to fixed lights, the exposed film being perforated and moved intermittently, and a slack length or loop of film being arranged between each printing point, so that no two adjoining pictures on the film are printed at the same period of exposure, and so that those parts of the film printed at the same time may be independently adjusted to their correct positions for exposure. After each exposure, a length of film equal to the number of pictures printed may be fed forward. A grid, which is given a continuous motion during exposure of the film, is arranged between the source of light and the film so as to cause the light to pass through the film at right-angles. Intermittently moving shutters are provided. Lamps of high actinic and low heating power, such as mercury-vapour lamps, are used. The negative and positive films A, A' may travel over two flat beds or plates C arranged on each side of a lamp B, as shown in Fig. 2, or arranged in line below two lamps, alternate pictures being printed at the two plates C between which is left a long slack length of film. Short slack lengths of film are left between the exposure apertures d in the clamping-plates D, and these parts of the films A, A' may pass on opposite sides of pins d<2> to facilitate their movement. The films A, A' are brought into register, positioned for exposure, and intermittently fed forward by sprocket-wheels G, travelling toothed bands, or reciprocating claws, the leading sides of the sprocket-wheel teeth being flat to ensure accurate registration of the films. Movable clamping-plates may be provided, or the films may pass over suction devices H, H<1>, Fig. 12, to produce a tensioning effect on them. The grid F and shutter E may be arranged as shown in Fig. 2, or a combined shutter and grid, with alternate spaces and blanks, may be used. Different films may be exposed on opposite sides of the lamps. The films may traverse crosswise a number of lamps, and in this arrangement, a number of separate films may be printed side by side, or the same films may be passed several times over the same lamps. Fig. 4 shows the beds divided into sections C' with gaps through which depend slack loops a of the films which may be equivalent in length to the length of ten pictures. The loops of the films at the bottom may pass in spiral form round rollers similar to those described in Specification 14,433/12, and in front of the exposure apertures the films pass over flanged rollers provided with sprocket-wheels and travel either transversely to or longitudinally of the lamp. The films may be moved backwards and forwards in a number of spirals transversely of a number of lamps. Fig. 12 shows the apparatus arranged to expose the films at a number of points arranged round a single lamp, the films being passed spirally round flanged rollers M and under pivoted clamping-plates D operated by a cam, and the loops of slack film passing over rollers M'. The screen E, which is moved to and fro by cam and ratchet mechanism, and the grid F, which is operated by an eccentric or cam, are arranged as shown.