GB821261A - Discharge lamp and phosphor therefor - Google Patents

Abstract

821,261. Luminescent materials ; discharge lamps. SYLVANIA ELECTRIC PRODUCTS Inc. Nov. 13, 1956 [March 2, 1956], No. 34742/56. Class 39(1). A luminescent material, particularly for use with a H.P. or L.P. mercury vapour discharge lamp, comprises a calcium zinc phosphate activated by stannous tin and containing between 2À50 and 2À98 moles of calcium oxide and zinc oxide, taken together, per mole of phosphorus pentoxide, so as to be mainly an orthophosphate. The phosphor can be activated by between 0À002 and 0À16, preferably 0À002 and 0À12, gram atoms of stannous tin per gram-mole of phosphorus pentoxide. The amount of zinc oxide can be between 0À1 and 0À8 moles per mole of phosphorus pentoxide. Preferred phosphors contain 2À65 moles of calcium oxide, 0À2 mole of zinc oxide and 0À06 mole of stannous oxide or 2À55, 0À30, and 0À25 moles respectively, per mole of phosphorus pentoxide. Several other samples and the effect of varying tin content are decsribed. Some tin can be present which is not in the stannous state. Various raw-mix constituents are described which can be fired in a reducing atmosphere of 2% hydrogen and 98% nitrogen, with or without preliminary firing in air. Ammonium chloride can be used as a flux. Firing temperatures of between 1600‹F. and 2100‹F are referred to. The luminescent material 1 can be applied, e.g. by an electrostatic coating method, to an outer jacket 2 containing an arc discharge tube 4 filled with mercury and an inert gas. The tube contains main electrodes 6 and 8, and an auxiliary electrode 10. A lead wire 14 is connected to electrode 8 by a metal ribbon 18 and a lead wire 16 has mounted on it a U- shaped support wire 20 to the legs of which are attached collars 22 and 24 encircling the tube. The free ends of the wire 20 are bridged by a plate 26 and are provided with resilient metal fingers 28 engaging the inner wall of the jacket 2. The lower parts of the legs of the wire 20 are provided with resilient metal fingers 30 and 32 also engaging the inner wall of the jacket 2. A resistor 34 is disposed on wire 20 and is seated on an insulator botton 35 which rests on the metal finger 32 so as to prevent contact between body of resistor 34 and wire 20. Lead wire 36 of resistor 34 is wound around wire 20 and is welded thereto. Lead wire 38 of resistor 34 is welded to metal ribbon 40 connected to auxiliary electrode 10. The upper end of resistor 34 is engaged by a depending flange 42 of collar 24.