Patent GB-763934-A (GB)
Title: Signal translation apparatus
IPC: H01J31/06
Filed: 1953-08-11
Abstract: 763,934. Electric selective signalling. BURROUGHS CORPORATION. Aug. 11, 1953 [Aug. 14, 1952], No. 22149/53. Class 40 (1).  [Also in Group XL (c)] An analogue voltage is sampled and translated into digital form by applying it to a selector-tube which selectively energizes - an output corresponding to the voltage amplitude during conducting-gating intervals of the tube. The selector tube outputs are connected to corresponding beam control electrodes of an electron beam switching tube so that the beam is deflected according to the selected output and produces directly, e.g. as disclosed in Specification 759,153, binary coded output corresponding to the sampled amplitude. Sampling, Fig. 3. The signal input wave 132, Fig. 7, to be sampled, is applied over a transformer 117 to the deflecting plates 80, 119 of a selector tube 760 which may be a known form of cathode-ray tube having target electrodes 81-90 on to which the electron beam is directed, selectively, according to the magnitude of the deflecting potential. Normally, the selector tube is cut-off. Negative pulses, Fig. 6, are applied to the sampling frequency, over a terminal 120 and a pulse lengthening stage 121 to the cathode 770 to operate the selector tube for the duration of each lengthened pulse, Fig. 5. The electron beam circuit is completed over the target electrode 81-90 selected by the signal input and the associated load resistor 103-112 to battery 113, the voltage drop in the operative resistor causing the potential of the selected target electrode to drop from 250 to 150 volts. Encoder, Figs. 1, 3. A thermionic tube, as described in Specification 759,153, is used. It comprises a central axial cathode 10, Fig. 1, space electrodes 11-20, equispaced around the cathode, a concentric cylindrical anode 24 surrounding the spade electrodes, and four vertically spaced collector rings 39, 40, 41, 42 surrounding the anode. When the electron beam is switched on it locks in on that spade electrode whose potential has been reduced to substantially that of the cathode, i.e. 150 volts. The beam, when it locks in, falls also on that pocket or portion of the anode between the lowpotential spade electrode and the next succeeding spade electrode. These anode pockets have vertical series of holes such as 25-30, Fig. 1, arranged according to the binary code so that when the beam falls on any one of the ten pockets it passes through a corresponding combination of holes to energize a corresponding combination of the collector rings 39-42, taken one, two or three at a time. Output signals in the binary code are taken from the voltage drops across load resistors 70-73, Fig. 3, connected to the respective collector rings. The tube is shown diagrammatically at 135, Fig. 3. Operation, Fig. 3. The negative impulses at sampling frequency also pass from terminal 120 directly to the grid of a triode 124 to cut-off the electron beam in the encoder tube 135, but owing to the pulse lengthening stage 121 the tube 135 is switched on again at the end of the impulse while the selector tube 760 is still switched on. The target electrodes 81-90 are connected respectively to corresponding spade electrodes 11-20 so that as the potential of the selected target electrode falls, as above described, that of the corresponding spade electrode 11-20 also falls causing the electron beam in the coder tube 135 to lock on to the spade electrode corresponding to the selected target electrode. The binary code value of the sampled input voltage is then taken from the voltage drops across the load resistors 70-73 and persists until the next sampling pulse cutoff the coder tube.