Patent GB-937669-A (GB)
Title: Electroluminescent instrument lighting
IPC: H05B33/00
Filed: 1960-09-05
Abstract: 937,669. Electroluminescence. SYLVANIA ELECTRIC PRODUCTS Inc. Sept. 5, 1960 [Sept. 8, 1959], No. 30538/60. Class 39 (1). Instrument lighting and indicating means having a dial and a pointer, such as a clock or speedometer, has the pointer 7, Fig. 2, formed as an electroluminescent lamp comprising a conductive piece 8 of circular or rectangular crosssection forming a centre electrode surrounded by a coating 15 including an electroluminescent phosphor surrounded by a transparent electrically conductive coating 16 forming an outer electrode, electrical connections 9, 21 and 13 leading from the electrodes 8 and 16 to a voltage supply. The electrode 8 can be of aluminium or of a chromium-steel alloy, e.g. that known as No. 4 Alloy comprising 42% nickel, 6% chromium, 0.29% manganese, 0.04% carbon and the balance iron, and is fixed to the rotatable hollow metal shaft 9 by collars 10, 11. A coating 14 having a dielectric constant of several thousand, e.g. a ceramic as described in Specification 809,099, can be fused on the electrode 8. The coating 15 can be a phosphor embedded in a ceramic as described in Specification 773,997. The transparent conductive coating 16 can be of tin chloride applied as described in Specification 773,997 and a glaze 17 of ceramic as described in the latter Specification can be applied over the coating 16. A coating 18 of a non-electroluminescent phosphor emitting red light under the radiation from the electroluminescent phosphor 15 can be applied over the coating 17. The various coatings can be formed by successive dippings and firings, a spot on the coating 16 being kept free from the coatings 17 and 18 for attachment of the connection 13 by painting the spot with an air-drying silver paint or baked-on silver or gold, placing the end of the connection 13 over the spot and applying a coating of epoxy resin. The connection 13 is enamelled. In a modification the electrode 8 can be of plastic or glass if conductive or if a conductive coating is applied thereto. The electrical connections from the movable pointer can be made by flexible wires or by movable contacts moving over fixed contacts. The dial, Fig. 3, comprises a base-plate 23 of aluminium or of No. 4 Alloy, referred to above, carrying a ceramic coating 24, a coating 25 of ceramic and electroluminescent phosphor, a transparent conductive coating 26 and a glass coating 27. The base-plate 23 forms one contact and a wire 28 connected to the coating 26 and led through an insulating bushing 29 the other contact. The base-plate 23 can be of enamelling steel, an additional coating of a glass having a coefficient of expansion nearer to that of the steel than the coating 24 being applied between the base-plate 23 and the coating 24, and can contain some glass or ceramic of high dielectric constant. An opaque dial 1 is coated on the glass coating 27, openings being formed for indicia, and can be of black or coloured paints or inks stamped or printed on the coating 27. A metal or plastic ring 6 encloses the outside rim of the dial. The indicia on the dial can be made to electroluminesce green, blue or white and the pointer red. The dial can be made in a dull circle or a part thereof and can be flat or convex. In modifications the pointer can move along a straight or non- circular line. Specification 809,099 also is referred to.