GB625256A - Gas discharge lamp - Google Patents

Abstract

625,256. Discharge lamps. PENNYBACKER, M. Oct. 25, 1945, No. 28245. Convention date, Dec. 23, 1944. [Class 39 (i)] A discharge lamp has two main electrodes 2, Fig. 1, and a conductive starting strip in the form of a straight channel unconnected to the circuit and provided with a porous insulating coating in the form of discrete particles ; the coating allows the passage of a glow discharge at starting, but resists the passage of any current after the main discharge has started. The starting strip 3 is of iron, nickel-plated iron, magnesium, aluminium, or of an alloy, coated with aluminium oxide, magnesium oxide, or with a fluorescent material, e.g. silicates. The metal may act as a reflector and the coating may be transparent, translucent, or reflecting. The strip may be elastic and is inserted into the tube as a separate unit ; it is preferably an exact semi-cylinder, but may extend for more or less than 180 degrees around the circumference of the tube ; in another form, Fig. 2B (not shown), it is V-shaped. Alternatively, the strip is of less elastic material and is held in place by a coating of adhesive material between it and the tube wall. The tube wall may be of quartz or of glass which transmits ultra-violet, and may be provided with fluorescent material or with a filter. The strip may also have a rear coating of porcelain enamel, and is placed at a predetermined position with respect to the contact pins so that it is in the correct position when the lamp is inserted into its socket. The power supply transformer has a poor regulation characteristic. The electrodes may be hot or cold starting. A plurality. of starting strips separated by gaps may be used. If two starting strips are used, Fig. 4 (not shown), their lengths may be in the ratio of 39 : 46. In all forms, the coating is applied by spraying, dipping, or dusting. The filling may be argon or an argon-neon mixture, at 3 mms., or at 1-5 mms. with the addition of mercury vapour. The Specification as open to inspection under Sect. 91 describes a form, Fig. 3 (Cancelled), in which the electrodes 11, 12, are separated by a partition 14 formed of metal, or of glass or mica coated with conductive material, and having an outer covering of insulating material. The insulating outer covering may also be fluorescent. This subject-matter does not appear in the Specification as accepted.