ES346374A1 - Digit tube with the characters secured only at one end - Google Patents

Abstract

In a glow-discharge character-display tube having a number of electrodes 01-91 in the form of characters arranged one behind the other, each character electrode is of chromiumnickel-steel alloy and is secured directly to a corresponding lead-in wire sealed through the base 17 of the tube and is supported by it. The lead-in wires extend through a mica centring plate 19 which is shielded by a metal plate 20 supported by two further lead-in wires (11 and 14, Fig. 2, not shown), and the character electrodes are preferably stud-welded to the ends of corresponding lead-in wires which are preferably of the same material. For shockresistant arrangements the character electrodes may be provided at their upper ends with lugs (not shown) secured in an insulating rod (not shown) which serves only to connect the electrodes together. An additional character electrode (25, Figs. 2 and 3, not shown) in the form of a full stop is preferably formed of a material of lower work function, e.g. iron or molybdenum, so that it will glow sufficiently brightly without using a higher voltage. A lead-in wire 15 has its end projecting above the plate 20 and is connected by a high resistance to the cathode supply voltage so that it does not glow but pre-ionizes the gas to increase the ignition speed of the characters. An anode (Fig. 1, not shown) is welded to the plate 20 and at its upper end carries a sheet metal support for a glass tube (23, Fig. 3, not shown) containing mercury. The metal support may be heated inductively or by radiation to release the mercury after the tube has been sealed.