Patent GB-448642-A (GB)
Title: Improvements in or relating to electrical signalling systems operating on the stroboscopic principle
Filed: 1935-01-08
Abstract: 448,642. Electric signalling systems. DEAN, W. H., 18, Cleveland Avenue, Darling- ton. Jan. 8, 1935, No. 661. [Class 40 (i)] In an electric signalling system having a stroboscopic receiver, the transmitter comprises a fixed arcuate electrode, a rotating electrode and a pointer, the position of which is to be signalled, sparks, which cause impulses to be transmitted, passing between the electrodes when the rotating electrode passes (a) the pointer and (b) a predetermined point in its path, the relative position of the two sparks being used to indicate the pointer position. At the receiver a disc or drum carrying a scale and a pointer is rotated in synchronism with the rotating electrode of the transmitter, the system being arranged so that the impulses generated by the sparks illuminate a neon tube placed behind the disc or drum when the arrow and the scale are respectively passing the viewing aperture, the cycle speed being such that both arrow and scale appear to be continuously illuminated. Readings of several instruments may be transmitted simultaneously over a single circuit, the incoming pulses being fed to individual stroboscopic instruments by a distributer. The apparatus for sending a single reading is shown in Fig. 1. The motors 32 and 15 run isochronously and power is fed to the system over rectifier 18. The arcuate electrode 14 and rotating electrode 16 are at high potentials and are separated by a distance greater than the sparking distance. Pointer 11 moves over scale 12 and is provided with a bridge piece 13 which is clear of both electrodes by a combined distance which is less than the sparking distance. When the rotating electrode passes the pointer a spark discharge passes between the electrodes over the bridge piece 13 causing an impulse train to pass through amplifier 27 which lights neon lamp 28. A similar discharge takes place when the electrode 16 passes extension 26 of electrode 14 and the lamp is again lit. The apparatus is arranged so that the pointer (such as 36, Fig. 4) and scale (such as 37, Fig. 4) are passing the aperture 31 as the lamp is flashed and, depending on whether arrow or scale is illuminated when 16 passes 26, the effect seen is either that of a fixed arrow co-operating with a scale moving in accordance with the pointer 11, or a fixed scale with the arrow simulating the pointer. For transmitting four readings simultaneously, the apparatus is arranged as shown in Figs. 5 and 6. The arcuate fixed electrodes 14 are arranged in different segments of the paths traversed by electrodes 16 whilst the extensions 26 correspond with spaces between the electrodes. A distributer 44 feeds the impulses in correct sequence to the four receiving instruments a<1>, b<1>, c<1>, d<1> and the cycle is arranged so that the fixed pulse of transmitters a, b, c and d are sent between the scale pulses of c and d, d and a, a and b, and band c respectively. The system may be arranged for any number of instruments by making the scales and arcuate electrodes of suitable length. Where two or more readings are being sent simultaneously, the motors at receiver and transmitter must run synchronously. One of the extensions 26 is arranged out of symmetry so that, if the indications should be appearing on the incorrect indicators, an out-of-centre indication is given. The indications can be changed over by movement of handle 52.