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US 5,744,233 AGranted
Method of coating luminescent powders, luminescent powders and coated object
AssigneeU.S. Philips Corporation
InventorsJoachim Opitz, Walter Mayr
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AssigneeU.S. Philips Corporation
InventorsJoachim Opitz, Walter Mayr
Estimating the term…
The invention relates to a method of coating luminescent powders with a coating which comprises silicon dioxide, which method is characterized in that in a first step luminescent particles are dispersed in a solution containing one or more metallo-organic compounds of silicon and, optionally, metallo-organic compounds of further elements in a hydrous solvent mixture having a pH-value of 1<pH 5, whereafter the metallo-organic compounds are hydrolysed by adding ammonia. A further aspect of the invention relates to a luminescent powder having a coating composed of silicon oxide and at least one oxide of a further element selected from the group formed by aluminum, barium, lead, boron, magnesium, titanium, zinc, zirconium, cobalt, copper and iron. Another aspect of the invention relates to a coated object, such as a fluorescent screen or display screen for a cathode ray tube or lamp or for other electrical discharge tubes or lamps, in particular also color television display screens, which is coated with a luminescent powder coated in accordance with the invention.
A method of providing luminescent powders with a coating comprising silicon dioxide comprising dispersing luminescent particles in a solution comprising at least one metallo-organic compound of silicon and, optionally, one or more metallo-organic compounds of further elements, in one aqueous organic solvent mixture having a pH value of 1<pH<5 and then adding ammonia to the resultant dispersion to catalyze hydrolysis of the metallo-organic compound(s) to oxides.
Dependencies are inferred from the claim text.