CATHODE RAY TUBE

PURPOSE:To maintain a good high vacuum condition inside a tube and offer a long-life cathode ray tube by forming an inside film containing activated carbon and alumina sol on the surface of material inside the tube except for a fluorescent face. CONSTITUTION:To prevent oxidation and burning of inside material in a frit sealing process, alumina sol is used as binder for the inside material containing activated carbon. The alumina sol is formed by, in general, dispersing fine alumina powder in water using acid stabilizer such as HCl, H2CO3, CH3COOH. For the alumina sol, alumina solid is preferably added so as to be within 0.1-10 pts.wt. to 1 pts.wt. activated carbon. As the alumina sol is used instead of water glass used in the past as binder which is added to the inside material, the decrease of activated carbon firing temperature due to alkaline metal in the water glass is prevented. As a result, there is no possibility of oxidation and burning of the inside material even when heated in a frit sealing process.