GB707850A - Photographic copying apparatus - Google Patents

Abstract

707,850. Photographic copying apparatus. HIGONNET, R. A. E., and MOYROUD, L. M. Aug. 18, 1952, No. 20723/52. Classes 98(1) and 98(2) Apparatus for composing images upon a photosensitive surface comprises a support for the said photosensitive surface, a support for a first imagecarrier, a support for a second image-carrier, a partial reflector adapted to reflect images from the first carrier and to transmit images from the second carrier, and an optical system for projecting the reflected and transmitted images on to the photosensitive surface. As shown in Fig. 1, a pedestal 6 in a casing 2 supports a block 4 comprising two right-angled prisms having a partially silvered contact face 18. Lens 8, 10 are mounted near the block so that an image of a film 12 bearing letterpress can be projected through the block on to photographic film 16, and an image of a film 14 can be projected by reflection at the surface 18 on to the film 16. A container 28 for film 16 has a dark slide 30 and is removable from the casing. It is mounted in front of a tapered light-tight tunnel 26 which is closed by a shutter 22, operated by a rod 24 to make an exposure. Images of films 12, 14 are also projected on to a ground glass screen 20. Film 12 bears original text, while film 14 bears lines of corrected text to be substituted for defective lines in the original. Each film is mounted in a lighttight box 56, Fig. 2, having an apertured base 48, and suspended before an aperture 44 in casing 2 by hooks 46 which engage rebates formed in a rack 42. Pinions 50 are mounted in the hooks to engage the rack teeth and move the box laterally when knobs 52 are turned. Shutters 58, 60 are movable in front of the film by a rack-and-pinion. The projection lamps 74 are mounted behind the film, and are of variable intensity. When lines of the original are to be replaced, part of film 12 is unmasked to project an image of the page down to the incorrect lines on to screen 20. Part of film 14 is also unmasked to project the correct lines under the image of film 12. The images are lined up on the screen by the adjustments provided. To facilitate adjustment + and - marks are printed at the beginning and end of each line. Since the reflecting surface transmits more light than it reflects, and the lamps are adjusted to produce equally intense images on film 16, the image of film 14 on screen 20 is brighter than the image of film 12. Other matter, such as pictures, can be projected from positions 32, 34 by means of mirrors 36, 38 which are turned when required to reflect light from these objects into the optical system. From single columns of text a double-column page form can be printed, with tables &c. of the full width of the page. Specification 669,531 is referred to.