GB777562A - Improvements in or relating to electric discharge tubes - Google Patents

Abstract

777,562. Glow discharge lamps. ERICSSON TELEPHONES, Ltd. and ACTON, J. R. Feb. 26, 1954 [March 9, 1953], No. 6403/53. Class 39(1). The composition and disposition of the electrodes and the nature and pressure of the gas filling in a glow discharge tube for use as a luminous signalling or indicating device in electronic counter or computer arrangements are such that a separate discharge glow may be maintained between a common anode and one or more of a plurality of cathodes, and each such discharge glow may be produced or extinguished independently of any other discharge glow within the tube. The tube shown comprises ten nickel rod cathodes 1 arranged a uniform distance apart in a circle with their discharge surfaces 1a spaced equidistantly from the discharge surface 2a of a dished circular nickel cathode 2. The cathodes pass through holes in a ceramic insulator 5 and a mica disc 9 which is sandwiched between an upper ceramic insulator 6 and a lower ceramic insulator (not shown) and has projecting teeth which engage the inner wall of the tube envelope 3 to locate the electrode assembly with respect to the envelope. The anode 2 is secured to a rod 4 which passes through the ceramic insulators into a ceramic sleeve 8 where it is attached to a wire 14 passing through the pinch 10. Each cathode 1 is fastened at its lower end to a wire 11 projecting from the pinch 10, each wire 11 and the wire 14 being attached to a base pin 12. The tube is filled with 99À5 per cent neon and 0À5 per cent argon at a pressure of 40 mm. of mercury, which together with the nature and disposition of the electrodes ensures that the difference between the striking and extinguishing potentials is less than forty volts. A number of discharges may be maintained simultaneously in the tube and may be viewed through an apertured plate covering the end of the tube envelope. The number of cathodes is not limited to ten, and the individual cathodes may be of rectangular or channel section and may be arranged in an arcuate row. The anode may be a disc or cylinder which in the latter case may surround the cathodes. Specification 712,171 is referred to.