METHOD FOR FORMING FILM INSIDE DISCHARGE TUBE FOR DISCHARGE LAMP

摘要

PROBLEM TO BE SOLVED: To provide a means for forming a film consisting of only prescribed molecules for the thin film on an inner surface of a hollow discharge tube 1 wherein a target 3 is sputtered or vaporized onto the inner surface of the discharge tube 1 which is at the same time irradiated by ultraviolet rays which decompose weakly combined molecules in the film. SOLUTION: A sputter electrode 2 which holds the target 3 containing same elements as the prescribed elements for the film that should be formed on the inner surface of the discharge tube 1 is inserted through an exhaust tube 12 and is set stably in the prescribed position inside the discharge tube 1. High frequency voltage is applied between the sputter electrode 2 and an outer electrode 4 made of a cylindrical mesh and at the same time ultraviolet rays are irradiated to the discharge tube 1 using a ultraviolet irradiation device 11. By using a sputtering method, the prescribed thin film is combined on the inner surface of the discharge tube 1. The weakly combined molecules in the film generated by the sputtering are decomposed by the irradiation of the ultraviolet rays, and nitrogen atoms which form the thin film are captured and form covalent bonds in mesh structures of oxidized silicon molecules at the inner surface of the discharge tube 1 made of a quartz glass and form the film firmly.