Tokyo Shibaura Denki Kabushiki Kaisha

Nobuyuki Tsuda

Masaaki Tamatani

Norio Koike

Nagai Hitosi

Sakae Ajiro

Fukaya Ajiro

A projection cathode-ray tube for a projection video apparatus, comprising a green-emitting screen including a terbium-activated lanthanum oxychloride phosphor. The disclosed phosphor exhibits a luminance maximum at a minimum beam size, a property advantageous for producing a high-resolution image. The phosphor is chemically stable at high temperatures. The phosphor shows no substantial decrease in emission efficiency even at about 80.degree. C., and the emission luminance is twofold that of the prior art. The green-emitting screen is made by the steps of: (a) settling the terbium-activated lanthanum oxychloride phosphor onto the inner surface of a cathode-ray tube, wherein the phosphor is settled from a suspension comprising a solution of potassium water glass and barium nitrate, and wherein the ratio of the weight concentration of potassium water glass to barium nitrate is in the range between about 20 to about 35; and (b) removing the resulting supernatant.

Projection CRT with a green emitting terbium activated lanthanum

A projection type green cathode ray tube (CRT) with improved brightness despite an increase in the temperature of the faceplate, a method for manufacturing a phosphor screen adopted therein, and a projection video device which utilizes the projection type green CRT. The phosphor screen of the CRT is formed of a cerium-activated calcium sulfide phosphor which contains 0.01 to 0.3 mol% of cerium. According to the method for manufacturing the phosphor screen, the cerium-activated calcium sulfide phosphor is precipitated in a 0.3 to 5% aqueous solution of water glass based on weight. The aqueous solution does not contain barium ions. The projection video device includes the green CRT, a red CRT having a phosphor screen which is formed of an europium-activated yttrium oxide phosphor, and a blue CRT having a phosphor screen which is formed of a silver-activated zinc sulfide phosphor. Brightness of images is improved and does not substantially change over time.

Growing community of inventors

Kawasaki, Japan

Nobuyuki Tsuda