Patent GB-786028-A (GB)
Title: Improvements in teletyping means for the printing or other indication of numbers andother information
IPC: G06K7/016
Filed: 1950-06-23
Abstract: 786,028. Electric selective signalling. DIRKS, G. June 23, 1950 [Oct. 1, 1948], No. 37208/54. Divided out of 786,021, [Group XIX]. Class 40 (1). Means including at least one electronic distributer (e.g. of the cathode-ray tube type), convert series-mode input signals representing information in a plurality of columns or demoninations to output signals in parallel. Signals for controlling printing mechanism of the type described in Specification 786,027, [Group XVI], are distributed under the control of a cathoderay tube 13. Signals recorded serially on a magnetic drum, disc or tape (or photo-electrically-sensed tape may be used) are picked up by a reading head 16 and, after amplification, fed to the control electrode 19 of the upper gun assembly of C.R.T. 13. A second reading head 21 picks up a sine wave synchronizing signal from the same recording surface which, in a known manner, controls voltages to the deflection system 25, 26, causing the electron beam to follow a circular path over a ring of target electrodes 20<SP>0-n</SP>. The lower gun assembly comprises only one set of deflecting plates 31, its electron beam following a linear path across targets 30<SP>1</SP>...30<SP>10</SP>, 30. These two distributers control a matrix of gas-discharge tubes 27<SP>1-n</SP>, 28<SP>1-n</SP>, &c., which serve to register, in static form, the pattern of signals read serially by the head 16. During each rotation of the upper electron beam those target electrodes 20<SP>0-n</SP> receiving the turned-on beam emit more secondary electrons and thus develop a positive charge which is sufficient to prime gas tubes 27<SP>1-n</SP> connected thereto through plug-and-socket means. A row of these gas tubes is selected when secondary emission from one of the targets 30<SP>1-10-0</SP> causes positive potential through a further plug connection to fire one of a column of tubes 35<SP>1-n</SP> which, by virtue of its cathode load 36<SP>1-n</SP>, raises the anode voltage of the selected row and causes the primed tubes 27<SP>1-n</SP> to fire. Each time the upper electron beam passes over the target 200 a signal via terminal c fires a gas tube 34, and a voltage developed across an inductor d cuts off a tube 37 and extinguishes the previously fired tube 35<SP>1-n</SP>. Discharges are maintained in the fired tubes 27<SP>1-n</SP> of the selected row, however, by a supply via a resistor 38<SP>1</SP>. The firing of gas tube 34 also causes a brief period of conduction in a pentode 33 and, consequently, steps up the charge on a condenser 32 which is connected, together with the C.R.T. deflection plates 31, to the anode of pentode 33. The change in potential here is sufficient to move the lower electron beam to the next target plate 30<SP>n</SP>, so completing the conditions for firing primed tubes 27<SP>1-n</SP> in another row. Upon reaching the target 30 the lower electron beam, through terminal a, serves to ignite a gas tube 29 which provides a discharge path for the condenser 32 and so brings the beam back to its initial position. The current in each of the discharging gas tubes 27<SP>1-n</SP>, 28<SP>1-n</SP> can be intensified by closing a switch 39 to short out a load in the H.T. supply. This provides sufficient energizing current to the printing magnets 3<SP>1-n</SP>, 4<SP>1-n</SP> to cause selective printing in the manner described in the Specification referred to above. More than one C.R.T..may be employed for distributing the input signals. - An arrangement for transmitting the signals by radio or line telegraphy to an additional remote printing or indicating unit, is also described. Both synchronizing and printing signals may be transmitted over a single channel and separated by frequency filters at the receiving end. Results of a computation may be checked by automatically comparing output signals from two distributers of the type described above, the inputs being the results of two successive computations. Specifications 786,022, 786,023, [both in Group XVI], 786,035, 786,036, [both in Group XIX], 786,041 and 786,043 also are referred to.