GB701378A - Improvements in or relating to electrical discharge tubes - Google Patents

Abstract

701,378. Cold-cathode tubes. ERICSSON TELEPHONES, Ltd., and ACTON, J. R. Aug. 9, 1951 [Aug. 14, 1950], No. 20117/50. Class 39(1) A cold-cathode tube, ir which a discharge space be tween an anode in the forrr of a metal rod or ring and a cathode in the form of a meta plate or dish extends betweer the anode and at least a cen tral part of one face of the cathode, has a filling of a reactive gas or a mixture of reactive and d non-reactive gases at a pressure within a range of 2 to 30 mm. inclusive of mercury. The tube is aged before use by passing a discharge between the elec trodes and has a negative resistance characteristic so that it may be connected ir series with a suitable resis tance to provide a voltage stabilizer arrangement or a source of reference voltage. The tube shown comprises a nickel rod anode 12 fastened to two leadout wires 15 at a point at which they adjoin and a molybdenum plate cathode 11 attached as by welding to three lead-out wires 14, each associated with a separate pin 19 in the base 18. A shield in the form of a nickel disc 16 is attached to three lead-out wires 17, but is not connected to any external circuit, its purpose being to protect the base 18 from direct electron bombardment during the ageing process and thus preserve the anodecathode insulation. A rectangular mica spacer 20 is attached to a nickel rod 21 fixed to the cathode and the electrodes are spaced so that the cathode 11 and anode 12 are substantially equidistant from the longitudinal axis of the bulb 13 which passes through the centres of the shield 16 and base 18. The gas filling is hydrogen at a pressure of 9.5 to 10.5 mm. of mercury. In a further embodiment the tube comprises a nickel wire ring anode mounted in a vertical plane coaxially with a circular dish-shaped molybdenum cathode.