GB906600A - Improvements relating to photocomposing machines - Google Patents

Abstract

906,600. Photographic type-composing apparatus; optical systems. MERGENTHALER LINOTYPE CO. May 7, 1959 [July 17, 1958], No. 15643/59. Classes 97 (1) and 98 (1). In a photographic type-composing machine including an array of graphic symbols or characters lit by a light source, there is provided for character selection one or more optical prisms through each of which light from all the characters in the array passes and means for positioning the or each of the prisms in any one of a chosen number of positions so that only light from a selected character will be deflected to pass along a predetermined path to form an image of the selected character. Since the number of different positions from which an image can be formed at a given position by means of n wedge prisms each having m different positions is m<SP>n</SP>, for an eighty-eight character font it is necessary to use for example a single prism having that number of different positions, two prisms each having ten positions or, say, seven prisms each having two positions. Thus with a single prism the characters are arranged on a circle centred at the centre of rotation of the prism or as shown with seven prisms 32, each having two positions differing by 180 degrees, the characters are arranged as indicated on the font plate 10 as indicated in Fig. 8. For such an array four prisms of angles, say, of 1, 2, 4 and 8 degrees would be arranged to deflect light horizontally and three prisms of angle 1, 2 and 4 degrees provide to deflect light vertically, while if a further prism is added for vertical deflection a more compact font plate array as in Fig. 10 may be used. To compensate for slight deviations due to differences in the angle of incidence of light from the array on the prisms, the array may have a slightly cushionshaped appearance (Fig. 11, not shown). Instead of rotating the prism 180 degrees to reverse its deflection, each prism may be replaced by a pair of prisms as in Fig. 4 displaceable across the optical axis in the direction of their aligned faces. A further arrangement of four prisms each having four different positions is referred to for an array as in Fig. 10, the deflections being effected in directions at 45 degrees to the rectangular co-ordinate lines shown.