Charactron

Abstract: 999,043. Electrophotographic and photographic recording. RANK-XEROX Ltd. (Haloid Xerox Inc.). July 26, 1961, No. 27138/61. Headings G2A and G2H. A high speed recorder records information represented by electrical signals on a light sensitive member. The signals are supplied to a cathode ray tube 10, e.g. a "Charactron" (Registered Trade Mark) from an electronic computer, data processor, or a magnetic data storage unit. An image in the form of alpha-numeric characters on the face 18 of the tube 10 is optically projected on to a endless belt, e.g. having a conductive backing 21 and a photoconductive layer 20. Alternatively, the light sensitive member may be a silver halide microfilm or a diazo material. The photoconductive layer 20 may be anthracene, sulphur, or vitreous selenium. The belt passes around rollers 23, 24 and 25, the roller 23 being driven by a motor 26 mechanically coupled to a tachometer 42. The belt is uniformly electrostatically charged by electrode 28 before exposure; the latent electrostatic image formed is developed by cascade apparatus 29. The developed image is transferred to a paper web 30 by an electrode 31 which applies a charge to the web of polarity opposite to the powder image. The motor 26 is under the control of a servomotor control 37. When a line advance signal is received, the electron beam in cathode ray tube is deflected downwardly by a deflection plate 33 or a deflection coil, such that the starting point of the line is deflected to the axis XA, Fig. 2. The display of characters along the line Z occurs in synchronism with the movement of the endless belt. The plate 33, Fig. 1, is connected to an amplifier 39 connected to the de-coding resistive network 35 of a reversible binary counter 35 which applies error signals to a position detector 36 connected to servomotor control 37. The tachometer 42 produces a voltage proportional to the speed of the motor which is converted into pulses by an analogue to digital converter 43, such pulses being fed to the binary counter 35. For repetitively printing the same format the cathode ray tube 10 may be provided with horizontal deflection plates 49, Fig. 7, while a control system 50, connected to the plates 33 and 49, is fed by a horizontal and vertical position memory unit 48. Instead of employing tachometer 42, the endless belt may have a variable density track 44, Fig. 6 (not shown) co-operating with a light source and photo-cell to produce electric pulses fed to the converter 43. Alternatively the belt may have magnetic marks detected by a pick-up head to produce the pulses.