GB757022A - Improvements in or relating to electric circuits comprising gas-filled glow discharge tubes - Google Patents

Abstract

757,022. Cold-cathode tubes. TELEFONAKTIEBOLAGET L. M. ERICSSON. Sept. 26, 1952 [Sept. 29, 1951], No. 24226/52. Class 39 (1). The ignition delay of a cold-cathode glow discharge tube is reduced by means of a preionizing electrode formed by an electrically conducting body with which a material, preferably glass, is associated in such a way as to be contiguous with said body and interposed between the latter and a further electrode with which the pre-ionizing electrode co-operates to form a priming gap. The tube is connected in a circuit in which the potential applied to the preionizing electrode is such that the current flowing through the material and across the priming gap is sufficient to decrease the ignition delay of the tube, but is not sufficient to lower appreciably the breakdown voltage of the main discharge gap of the tube. Fig. 2 shows a tube comprising an anode 1 and cathode 2 connected through a switch 11 to a voltage source 4. A pre-ionizing electrode 3 comprising a leadin wire 12 and a coating 9 of glass or other semiconductive material forms a priming gap with the cathode 2 and is supplied by a separate source 10. The coating 9 acts as a limiting resistance in the priming circuit. Alternatively the electrode 3 may form a priming gap with a further auxiliary electrode or with the anode. In a modified arrangement the electrode 3 is connected directly inside the tube to either the anode or the cathode, in which case the voltage source 4 also maintains the priming discharge. A trigger electrode may then be connected through a switch to the source 10. In the arrangement shown in Fig. 4 the preionizing electrode 3 comprises a band 12 of metal or carbon on the outer surface of the tube envelope, a portion 9 of the glass envelope itself forming the limiting resistance. The Specification describes a circuit including an electronic time meter used for investigating the effect of the pre-ionizing electrode on the ignition delay as compared with the effect of placing a small quantity of radio-active cobalt in a tube similar to that shown in Fig. 4 and having a filling of neon and 1 per cent argon at a pressure of 70 mm. of mercury.