GB346668A - Improvements in or relating to the preparation of photographic sound records - Google Patents

Abstract

346,668. Changing signs. BENNETT, D. T., Garrydene, Green Dragon Lane, Winchmore Hill, London. Jan. 9, 1930, No. 887. [Class 3 (i).] Neon lamps, or other electric glow-discharge devices have one electrode comprised at least in part by a resistance through which varying currents flow to vary the glow. In an electric sign, the electrodes are in the form of symbols. The resistance electrode 13, Fig. 1, may be a carbon filament or a coiled wire arranged alongside an equipotential electrode 12. A battery is connected between the electrode 12 and one end 14 of the electrode 13 and a second battery 17 is connected to the electrode 13 to produce a steady fall of potential along it. The varying currents are applied through a transformer 20 and modify the potential fall along the electrode 13 and so to the extent g to which the glow extends along the electrode from the end 14. In a modification, the battery 15 is connected to the centre of the electrode 13 whilst the battery 17 and transformer 20 are duplicated or are arranged in a common circuit between this centre and both ends of the electrode 13. The glow then extends from the centre towards both ends to a varying extent. The glow may also extend from the ends of the tube towards the ceutre. The glow may vary in intensity as well as in area. In other modifications, the electrode 12 and the source 15 are omitted, the electrode 13 being doubled back on itself into U-shape or into the form shown in Fig. 5 and the glow occurring between opposite parts of the electrodes 13. The resistance 13 need not be constant per unit length and the electrodes or limbs of the resistance electrodes need not be straight or parallel. The electrode 12 may be U-shaped in cross section with the electrode 13 within it. The discharge tube may have two resistance electrodes.