Kasei Optonix, Ltd.

Hidemi Yoshida

Takashi Hase

Hideo Suzuki

Morio Hayakawa

A sulfide phosphor emitting green to orange light with long after-glow is represented by the formula of (ZN.sub.1-x,Cd.sub.x)S:eM.sup.I',fM.sup.III', gX' wherein M.sup.I' is at least one of copper and gold, M.sup.III' is at least one of gallium and indium, X' is at least one of chlorine, bromine, iodine, fluorine and aluminum, and x, e, f and g satisfy the conditions of 0.ltoreq.x.ltoreq.0.4, 10.sup.-8 .ltoreq.e.ltoreq.10.sup.-2, 5.times.10 .sup.-8 .ltoreq.f.ltoreq.5.times.10.sup.-3, and 5.times.10.sup.-8 .ltoreq.g.ltoreq.5.times.10.sup.-3. A white emitting phosphor is obtained by mixing the long after-glow yellow emitting phosphor represented by the above formula wherein 0.ltoreq.x.ltoreq.0.3 and 10.sup.-6 .ltoreq.e.ltoreq.10.sup.-2, with a long after-glow blue emitting phosphor. These sulfide phosphors are used to form fluorescent screens of electron excited fluorescent display devices.

Phosphor and electron excited fluorescent display device using the same

A monochrome display cathode ray tube which comprises a white emitting fluorescent screen formed on a face plate facing an electron gun to emit cathode rays, said white emitting fluorescent screen being composed essentially of a phosphor mixture comprising from 40 to 70% by weight of a long after-glow red emitting europium-activated indium borate phosphor, from 10 to 40% by weight of a long after-glow green emitting manganese-activated zinc silicate phosphor and from 10 to 50% by weight of a long after-glow blue emitting silver-activated zinc sulfide phosphor.

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Odawara, Japan

Hidemi Yoshida