Kasei Optonix, Ltd.

Dai Nippon Toryo Co., Ltd.

Thihiro Yoshida

Noboru Kotera

Shusaku Eguchi

Kazuhito Iwasaki

Katuzo Kanda

Seiji Murakami

Toshiaki Hatsumi

Isao Iwamoto

Shusaku Kakita

Hiroshi Uchida

A cathode ray tube having a fluorescent screen of a copper and aluminum activated zinc sulfide phosphor (ZnS:Cu,Al). The ZnS:Cu,Al phosphor has a Cu activator value ranging from 3.times.10.sup.-4 to 5.times.10.sup.-3 grams per 1 gram of ZnS; an emission color point within a yellowish green region in the color coordinates of CIE color system represented by values x and y ranging from 0.295 to 0.370 and 0.570 to 0.630, respectively; a color point of body color within a yellow region in the color coordinates of CIE color system represented by values x and y ranging from 0.380 to 0.400 and 0.390 to 0.440, respectively; and a mean reflectance in the visible spectrum region of not less than 75% when the mean reflectance of a magnesium oxide diffusion plate is defined to be 100%.

Cathode ray tube

In a phosphate fluorescent substance including orthophosphate as a parent material and manganese as a main activator, said phosphate fluorescent substance has at least one of the following features (I) and (II): (I) The maximum intensity point in the glow curve is within the range of 200.degree.-400.degree. C. and (II) Ia/Ib is within the range of 0.6-3.0.

Phosphate fluorescent substance

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

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

Growing community of inventors

Hatano, Japan

Thihiro Yoshida