Method and apparatus for forming a thin film on an outer surface of a display screen of a cathode ray tube

A method of forming a thin film on an outer surface of a display screen of a cathode ray tube, comprising the steps of:

• applying a film formation material solution having a volatile solvent and silicon alchoholate on said outer surface of said display screen to form a solution film;
• rotating said cathode ray tube around an axis thereof to obtain a uniform film thickness of said solution film on the outer surface;
• a first heating step of applying a first quantity of hot air to a central portion of said cathode ray tube for a first time, during said rotating, such that hot air of a first temperature reaches said central portion;
• a second heating step of applying a second quantity of hot air to said central portion of said cathode ray tube for a second time, during said rotating, such that hot air of a second temperature reaches said central portion, said second temperature being higher than said first temperature;
• and
• a third heating step of applying a third quantity of hot air to said central portion of said cathode ray tube for a third time, during said rotating, such that hot air of a third temperature reaches said central portion, said third temperature being higher than said second temperature, thereby producing SiO from said silicon alcoholate in said film formation material solution to form the thin film including SiO.sub.2 on said outer surface.