Kasei Optonix, Ltd.

Hitachi, Ltd.

Dai Nippon Toryo Co., Ltd.

Katuzo Kanda

Shusaku Eguchi

Kazuhito Iwasaki

Noboru Kotera

Yoichi Oba

Thihiro Yoshida

Seiji Murakami

Toshiaki Hatsumi

Isao Iwamoto

Masaaki Hayashi

Hiroshi Takada

Tsuyoshi Kano

Hidenaga Horiuchi

Pigment coated phosphors comprising a europium activated yttrium oxysulfide phosphor having a europium activator value within a range of 0.04 gram atom to 0.066 gram atom per 1 mol of yttrium oxysulfide having adhered thereto red colored pigment particles such as cadmium sulfoselenide pigment particles, rouge pigment particles or red lead pigment particles, in respective amounts of 0.1 to 2.0 wt %, 0.05 to 2.0 wt % or 0.1 to 12 wt %, based upon the europium activated yttrium oxysulfide phosphor; and a cathode ray tube for high contrast color television using as a red emitting phosphor at least one of the three pigment coated phosphors.

Pigment coated phosphor and high contrast color television cathode ray

Pigment-coated phosphors which may be used in the production of a cathode-ray tube of a high contrast for a color television receiver can be produced by adding a pigment and an anionic polymer emulsion to an aqueous suspension of a phosphor and then making the system neutral or weakly acidic or adding a cationic polymer emulsion or carrying out both of these steps so that the phosphor and the pigment may be coated with the polymer.

Process for producing pigment-coated phosphors

A pigment-coated phosphor having good finish sieve passability and capable of forming a fluorescent film with excellent properties can be produced from a process characterized by:

A pigment coated phosphor used as a green emitting phosphor for a high contrast color television cathode ray tube. A green emitting phosphor is coated with TiO.sub.2 --ZnO--CoO--NiO system pigment particles.

Pigment coated phosphor

On the surface of a phosphor, pigment particles are uniformly adhered by a layer of a gelatin-gum arabic mixture. A process for manufacturing such a pigment coated phosphor includes the steps of preparing an aqueous solution of gelatin and an aqueous solution of gum arabic, allowing the phosphor to disperse homogeneously into one of these aqueous solutions, allowing the pigment particles to disperse homogeneously into the other aqueous solution, and mixing the so obtained phosphor and pigment dispersions.

Pigment coated phosphor and process for manufacturing the same

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