GB315369A - Improvements in and relating to gaseous conduction electric lamps - Google Patents

Abstract

315,369. British Thomson-Houston Co., Ltd., (Assignees of Moore, D. M.). July 12, 1928, [Convention date]. Vacuum tubes.-A gaseous discharge lamp with a negative glow discharge which is responsive without appreciable time lag to voltages of the order of radio frequency, and for use in television apparatus &c., comprises a tubular anode into which the cathode is tightly fitted and separated therefrom by only a thin insulating layer. In the construction shown in Fig. 1, the active face of the cathode 14 is flush with the end of the anode 13, a thin insulating layer 16 confining the glow to the exposed surface of the cathode. Depressions of various shapes may be made in the face of the cathode to confine the glow to the centre thereof. In the construction shown in Fig. 7, a deep conical depression 38 is formed and the anode is extended over the face of the cathode and provided with an aperture 40 registering with the mouth of the depression 38. The depression may be of inverted conical form as shown at 34, Fig. 5, the glow being confined to the interior conical surface. In the construction shown in Fig. 3, the depression is in the form of a narrow bore 23 giving an intense spot of light. The leading-in wires may be connected to an ordinary lamp base or may be led in from opposite sides 'of the bulbs as shown at 31, Fig. 5. The electrodes may be steadied by fitting closely in a tubular envelope as shown, or if the support wires are sufficiently robust the electrodes may be mounted in a spherical or like bulb. The gas filling may be of argon, or of pure or commercial neon, the latter containing about 20 per cent of helium. A neon filling may contain about 0.5 per cent of argon. The gas pressure is about 30 mm. The anode may be of aluminium, magnesium, iron, copper, or nickel, and the cathode of nickel, aluminium, or magnesium.