GB786092A - Cathode ray character tracer - Google Patents

Abstract

786,092. Photo-electric control of character display apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 12, 1955 [April 15, 1954], No. 10442/55. Class 40 (3). [Also in Group XL (c)] The arrangement comprises a C.R.T. with deflecting means for causing the electron beam to sweep selected regions of the screen several masks in the light path from the tube screen, optical elements arranged to cause the light to fall simultaneously on the part of each mask which corresponds to the selected region of the tube screen, and light-sensitive means associated with each mask so as to receive the light passing therethrough and to produce a voltage varying with the intensity of the received light. The varying voltages produced by this arrangement may be applied to the deflecting means of another C.R.T. so that a character is traced on the screen thereof and may be photographed. As described, amplified pulses from a multivibrator 10, Fig. 1b are fed to a timer ring 13, including nine trigger circuits so arranged that as one trigger is turned ON the preceding trigger is turned OFF. This ring is in circuit with a gate 48 and a sweep circuit 22 to feed one saw-tooth wave to an X positioning circuit during the time that triggers 2 to 9 in ring 13 are ON, and with a power unit 14 feeding X and Y rings 15, 16, each having seven trigger circuits. Each trigger is associated with a power unit arranged so as to produce a different voltage output which is fed to X and Y positioning circuits connected to the deflection plates or cathode-ray tube 21, Fig. 1a. By this means, selected areas of the screen of tube 21 are arranged to be swept, each area corresponding in its position on the screen with a part of each of three masks 34, 28 and 30 through which light from the selected area is caused to pass by optical elements including beam splitters 33, 29, the light passing through the masks faces on associated photo-cells 36, 28 and 32 respectively connected to the X, Y and Z plates of a cathode-ray tube 37. Thus, by suitably patterning the opaque parts of the several areas of the masks, the varying potentials applied to the deflection plates of tube 37 will cause the electron beam to trace out a character on the tube screen, which may be photographed at 41. Successively formed character tracings may be arranged sequentially on the screen by mixing the voltage from photocell 36 with a.voltage generated by power unit 14 and trigger circuits 49 and feeding the mixed voltage to the X plate of tube 37.