GB875314A - Improvements in or relating to multi-electrode gas-filled discharge tubes - Google Patents

Abstract

875,314. Multi-gap cold-cathode tubes. ERICSSON TELEPHONES Ltd. May 23, 1960 [June 9, 1959], No. 19761/59. Class 39(1). A multi-electrode cold cathode gaseous discharge sequence or counter tube comprises a central anode 14 supported by a rod 11 which passes through the tube base 10 to form a valve pin and a surrounding ring of cathodes 15 aligned with respect to the anode by means of an insulating structure mounted on the rod 11. The central electrode, however, may be a cathode and the surrounding electrodes anodes. The insulating structure consists of four ceramic discs 17, 18, 19 and 20 and upper and lower ceramic sleeves 16 and 21. A mica disc 23 sandwiched between ceramic discs 18 and 19 spaces the structure from the tube wall. The mica disc is provided at its edge with small triangular ears 24. The ring of cathodes 15 comprises independent cathodes 15a which extend to tube pins, and first, second and third guide electrodes which extend respestively to metal discs 25, 27 and 28 sandwiched between ceramic discs 19 and 20, ceramic disc 18 and mica disc 23, and ceramic discs 17 and 18. One electrode of each group of guide electrodes, e.g. 15b, extends down to a valve pin. Getter supports 29 are welded to two remaining valve pins and another pair of the total of seventeen valve pins are unused. The rod 11 supporting the central electrode may be offset from the axis of the insulating structure. The central electrode may be supported by more than one rod. Specifications 712,171, 712,215, 721,058 and 777,362 are referred to.