GB395804A - Improvements relating to luminous gas discharge tubes - Google Patents

Abstract

395,804. Discharge lamps. UNEON, Ltd. and SOUNDY, L. H., Vincent House, Vincent Square, London. Feb. 29, 1932, Nos. 6062 and 11753. [Class 39 (i).] Discharge lamps of flashing signs &c. are operated by intermittently short-circuiting the positive column whilst maintaining the flow of current near the cathode. In a neon lamp for direct current, an auxiliary electrode d, Fig. 1, near the cathode b is connected to the anode f through an intermittently closing switch s. The voltage interrupted by the switch s is that across the positive column and not the higher voltage across the electrodes b, f. The electrode d may be of metal gauze at the junction of the positive column and the Faraday dark space but may be nearer the cathode b either in the Faraday or Crookes dark spaces or in the negative glow. In an alternating current lamp, two auxiliary electrodes, one in front of each main electrode, are connected together through the switch s. To extinguish portions of the positive column in sequence, other gauze electrodes may be provided at points along the tube. The tube may be shielded from sight at its ends beyond the auxiliary electrodes. To improve the extinction of the positive column by reducing the escape of ions around the electrode d, this electrode may be circular and may extend near to the walls of the tube; for example, half-way between the circumference of the electrode b and the walls, or the electrodes may be arranged as shown in Fig. 4. The main electrode b is here hollow and is surrounded by insulation l such as steatite, dental plaster or porcelain to produce a discharge spreading from the aperture m. The electrode d is surrounded by insulation n and is carried by, and may be adjustable on, rods p moulded in the insulation l. The electrode b is of iron, aluminium or tungsten. The electrode d is of aluminium, nickel, iron, tungsten, or molybdenum and may be coated with electron emissive material.