Patent GB-799116-A (GB)
Title: Improvements in or relating to photographic type-composing machines
IPC: B41B21/24
Filed: 1956-12-28
Abstract: 799,116. Photographic type-composing. MERGENTHALER LINOTYPE CO. Dec. 28, 1956 [Dec. 30, 1955], No. 39490/56. Class 98(1) A photographic type-composing machine includes a font of typographical characters, a small lens for each character, a mounting for each small lens so arranged with respect to the font that each character is substantially axially in the focal plane of its small lens, an imaging lens arranged to bring an image of any character by way of its associated small lens to a common position in the focal plane of the imaging lens, and an official device for each small lens to correct any deviation of the principal axis of the small lens from parallelism with the principal axis of the imaging lens. As shown in Figs. 1 and 2, the small lenses 27 are mounted in a disc 21, consisting of several laminations. The lenses 27 are supported in apertures 26 in the central aluminium disc 25, which also has threaded holes for locking screws 30, 31. Plates 32, 33 of half-hard brass, plates 35, 36 of hard aluminium, and clamping plates 41, 42 are placed on opposite sides of the disc 25, and have clearance holes for screws 30, 31. Although screws 30 pass only through plates 32, 35, 41, and screws 31 pass only through plates 33, 36, 42, both sets of clearance holes are formed in all plates to reduce the number of different parts. The plates are held together by nuts and bolts 23, 22 and have registering apertures 24. The members for adjusting the optical axes consist of optical wedges 50, see also Fig. 2A, mounted on opposite sides of the lenses 27 in tubes 46 accommodated in apertures 37 in plates 35, 36. The square surfaces of wedges 50 engage shoulders 51 in the tubes 46, and the ends of the tubes bear against the edges of apertures 34 in plates 32, 33. The tubes also pass through apertures in clamping plates 41, 42 which engage shoulders 45 on the tubes 46. As shown in Fig. 5, the complete assembly 20 is mounted in an aperture 62 in a frame 61. A pin 65 on a bracket 63 engages the registering apertures 24 to orient the assembly, which is held in position by clamps 67. To adjust the small lens assemblies, the assembly 20 is set up; as shown in Fig. 7, before a target array 75. This array has a number of transparent figures, e.g. crosses, having positions in the array corresponding to the positions of the characters in the character array, and is illuminated by a lamp 72 and condenser 74. Rays from each figure are rendered parallel by the lenses of the assembly 20, and light from a figure selected by a shutter system 76 passes to a lens 80, of sufficient aperture to cover all the small lenses, so that an image is formed at 77, after reflection at a prism 81. This image is projected on to a screen 84 by a lens 82 and reflectors 83, 85. The shutter is actuated to pass light through a first small lens, and the position of the image on screen 84 is noted. The tube 46 containing the optical wedges are locked by tightening the screws 30, 31 adjacent thereto. The other lenses are brought into operation one at a time and in sequence, and by rotating tubes 46 by means of their slots 47, the wedges are rotated to bring the images to the same position on screen 84, the tubes being locked by the adjacent screws 30, 31 after adjustment. Owing to the thinness of the clamping plates 41, 42, only the tubes next to a tightened screw are clamped thereby. The pair of wedges may be replaced by a single wedge, the angle of which is a function of the degree of decentring of the associated lens, or by a plane parallel plate mounted to pivot about a point. Specification 746,562 is referred to.