Luminescent materials
AssigneeThorn EMI plc
InventorsPeter W. Ranby, David R. Palowkar
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Abstract
A phosphor for use in fluorescent lamps which comprises calcium sulphate and, optionally, up to 50% of strontium sulphate together with cerium (0.5-10%), manganese (up to 10%), an alkali metal (0.001 to 3%) and boron and/or aluminium (0.001 to 8%). The phosphor may be produced by blending and then firing the individual components. Tubes for use in the lamps may be electrostatically coated with the phosphor.
Claims12
A phosphor for use in a fluorescent lamp which comprises an alkaline earth sulphate of which at least 50% of the alkaline earth of said alkaline earth sulphate is calcium but wherein up to 50% of the alkaline earth of said alkaline earth sulfate may be strontium, with the balance of said alkaline earth being calcium, and which additionally contains the following percentages by weight of the alkaline earth sulphate
- (a) from 0.5 to 10 of cerium,
- (b) up to 10 of manganese,
- (c) from 0.001 to 3 of an alkali metal selected from lithium, sodium and potassium, and
- (d) from 0.001 to 8 of boron.
Dependencies are inferred from the claim text.