GB704968A - Improvements in or relating to gaseous electric discharge tubes - Google Patents

Abstract

704,968. Multi-gap cold-cathode tubes. STANDARD TELEPHONES & CABLES, Ltd. Jan. 3, 1951, No. 243/51. Class 39(1) A cold cathode unidirectional sequence discharge tube comprises electrodes defining an array of glow discharge gaps arranged in line in pairs in such manner that the ionization. coupling between the two gaps of each said pair has a large value while the ionization coupling between each two adjacent gaps not of the same pair has a smaller value than that appropriate to the shaping of the electrodes. In one electrode arrangement, Fig. 5, an anode 21 co-operates with cathodes 22, designated storage cathodes and cathodes 23 designated transfer cathodes, the cathodes being evenly spaced from one another at a separation less than the length of the cathode dark space. Insulating barriers 24, located between adjacent pairs of cathodes and partially overlapping them, project towards the anode a distance of the order of the length of the cathode dark space, and have the effect of reducing the ionization coupling between, say, the storage cathode 22c and the transfer cathode 236 to some 40 per cent, while the coupling between storage cathode 22c and transfer cathode 23c remains 100 per cent. Coupling between adjacent storage cathodes is reduced by curtains 25 of insulating material secured to an insulating sheet 26 on which the anode 21 is mounted. A similar electrode assembly is supported on a platform 38, Fig. 6, in an envelope 28 having a glass base 29 through which project pins 30 to which leads from the electrodes are welded. The ends 32 and 33 of a strip metal anode are bent over the ends of a sheet of insulating material 31. The cathodes 22 and 23 are formed of metallic strips clamped between and projecting from opposite sides of an insulating sheet 34 and a mask of insulating material 35. Rectangular slots are formed in the mask to expose the discharge surfaces of a pair of cathodes, and the portions of the mask separating adjacent slots constitute the barriers 24. The curtains 25 are formed by the transverse portion of H-shaped members 36 which space the anode from the cathode array, the assembly being locked together by rods 37 eyeletted to the corners of the insulating sheets. In a simple modified arrangement, the barriers 24 and curtains 25 are omitted, the directional feature being obtained by locating the transfer cathode of each cathode pair close to the storage cathode of the same pair with a wider spacing between adjacent cathodes not of the same pair. With nickel electrodes in a gaseous atmosphere of 92 per cent neon, 1 per cent argon, and 7 per cent hydrogen at 100 mm. pressure, the spacing between cathodes of the same pair is 0.010 inch and between cathodes not of the same pair 0.025 inch. In a further modification, curtains of insulating or of metallic material are provided between successive pairs of cathodes and the transfer cathodes are made considerably longer in the direction of the array than the storage cathodes. Specifications 639,827, 691,901 and 692,415 are referred to.