Patent GB-912201-A (GB)
Title: Improvements in or relating to phototypesetting machines
IPC: H03M1/00
Filed: 1959-03-12
Abstract: 912,201. Photographic type-composing apparatus. HARRIS-INTERTYPE CORPORATION. March 12, 1959 [March 12, 1958], No. 8609/59. Class 98 (1). Character selection apparatus for a photo-type setting machine comprises a matrix having a plurality of characters defined therein by parts of differential light transmitting properties, a controllable flashing light source of relatively high intensity and short duration, the matrix and light source being mounted for relative movement therebetween to align the light source and individual characters in predetermined succession, code representation on the matrix associated with and identifying each of said characters and formed by a plurality of impulse generating means selectively arranged in two locations on the matrix pattern characteristic of the character, reading means for scanning each of the two locations during relative movement between the matrix and the light source to determine the sequence in which the impulse generating means for each character are arranged, a character selector including means for temporarily retaining code data corresponding character selected, a comparing device connected between the sensing means and the selector for comparing the code representation for each character with the code data in the selector, and an output from said comparing device for passing a signal to the light source whenever the code representation for one of the characters coincides with the code data in the selector corresponding to the selected character. The characters A, B, C . . . formed by opaque delineation on a transparent rotating disc 10, or vice versa, are illuminated when selected, by an intense light from an are 17 and optically projected by lenses 20 on to a photo-sensitive sheet mounted on a drum 22 rotated or stepped to provide letter spacing. The disc 10 also carries code marks representing the various characters in binary notation, the lines 30 in the outer positions representing " 1 "s and the lines 32 in the inner positions being representative of " 0 "s, the code being suitably spaced from the corresponding letters and all separated by lines 35 extending across the " 0 " and " 1 " positions to produce pulses simultaneously on photo-cells PC1, PC0 positioned to respond to the radial lines in the " 1 " and " 0 " positions respectively. Pulses from the cells PC1, PC0 pass via amplifiers 42, 52 to the respective grids 45G1, 55G1 of pentodes 45, 55 and also to an " AND " circuit 190. The 7-unit code of a character to be photographed is set up on flipflops FO(70) . . . F6(76), a flip-flop in the state " 1 " providing a positive pulse to the righthand (r.h) grid of a valve 80P1 . . . 86P1, and in the state " 0 " applying a positive pulse to the left-hand grid of the double triode valves 80P1 . . . 86P1. The codes set up on the flip-flops 70 . . . 76 and the code pulses produced from the binary code markings 30, 32 on the rotating disc 10 are compared by the operation of a beam-switching tube 110 having targets 120 . . . 126 connected to the pairs of cathodes of the valves 80P1 . . . 86P1, the even-numbered (140. . .) and odd-numbered (141 . . . ) grids being connected to the alternative outputs of a flip-flop 62. The spades 121 . . . are connected to earth and the spade 120 to an amplifier 65 providing a restoring pulse when the "AND"  circuit 190 is operated by simultaneous pulses from PC0 PC1 in response to a separating line 35 between sets of code marks 30 representing characters. When the successive pulses from the disc 10 are in agreement with those from the flip-flops 70 . . . 76, pulses are applied to both grids 45G1, 45G2 or 55G1, 55G2 of the pentodes 45, 44 passing pulses in succession to the flipflop 62 so that the beam is switched from target 120 until it reaches target 127 from which a pulse passes via amplifier 176 to switch all the flip-flops 70 . . . 76 to their zero or rest condition. At the same time a sharp pulse passes from the spade 137 to amplifier 172 to produce a spark at 17 to project an image of the appropriate character A, B . . . on the disc 10 on to the sheet on the drum 22. If there is discrepancy between the binary code detected on the disc 10 and the code set up on the flip-flops 70 . . . 76, the beam switching is interrupted, and the beam in the tube 110 is restored to its normal position to begin another comparison before it can reach the spade 127 to operate the arc gap 17. More than one character can be reproduced during a revolution of the disc 10 if selecting codes are fed at the appropriate rate to the flip-flops 70 . . . 76. In a modification, Figs. 3, 4 (not shown), with operation generally similar to that described in respect of Fig. 1, the binary code of the desired character is set up on seven bi-stable trigger circuits with two outputs of each connected to a respective grid of each of a pair of associated pentodes, having two other similar grid suppressors connected to photo-cells similar to PC1, PCO of Fig. 1. In a further arrangement, Fig. 5 (not shown), generally similar to that of Fig. 3 (not shown), a separate beamswitching tube is employed to control the comparison of the binary elements derived from the disc with those set up on the seven flip-flops or triggers in accordance with the desired character. The additional beam-switching tube is controlled and stepped through an " OR " gate opened by pulses from either of the photocells PC1 or PCO. The beam-switching tube which in the two other embodiments controlled the printing operation and also controlled operation of the comparison circuits, operates solely in the arrangement of Fig. 5, not shown, to initiate the printing operation when the discharge has been stepped seven times due to identity between the binary code on the disc and the code set up on the registering flip-flops or bi-stable triggers. Specifications 768,374, 891,142 and U.S.A. Specification 2,944,472 are referred to.