International Standard Electric Corporation

Nokia Graetz

Gerhard Mauz

Volker Gerstle

Rolf Zondler

Heinz Beckerle

During the formation of a black-matrix layer on the inside surface of a faceplate of a color picture tube, the development of the photoresist coating takes place in an atmosphere with a relative humidity of between about 80-100% and at a temperature of between about 30.degree.-50.degree. C.

Process and apparatus for producing a black matrix layer

To a suspension of rare-earth phosphors and sulfidic or selenidic phosphors there is added about 1 to 2% of the amount of hypohalogenite which would be necessary to convert the entire sulfidic or selenidic chalcogenide phosphor into a soluble sulfate and/or selenate. When acidifying the dispersion to which hypohalgenite has been added, to a pH value of preferably between 1.5 and 2, a sedimentation of elementary sulphur and/or selenium forms and becomes attached to the sulfidic and/or selenidic phosphor solids, thus causing these phosphor solids to form sediment. The supernatant suspension containing the rare-earth phosphor is then decanted, and the rare-earth phosphor is reclaimed from the suspension. The disclosed reclaiming process is particularly suitable for decontaminating phosphor mixtures for use in manufacturing color television cathode-ray tubes.

Process for reclaiming rare-earth metallic oxide and/or rare-earth

Method of preparing a phosphor suspension by mixing a photosensitive material, a photosensitizer, and a phosphor for the purpose of forming a photosensitive film. The photosensitizer in the suspension is a chromic-acid solution. With such a phosphor suspension, a firmly adhering, uniform and compact phosphor film can be formed on the screen substrate. In addition, the phosphor areas obtained by this method have very sharp boundaries.

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Kongen, Germany

Gerhard Mauz