| 摘要 |
PURPOSE:To improve productivity and yield, by heating electrodes and the whole main tube provided with an inserted inert gas leading-in pipe, through a heating process divided into steps of the predetermined number of times or more, and sealing the electrodes on both ends and forming the luminous portion of a luminous tube at the same time. CONSTITUTION:Electrodes 2, 3 held by electrode holding apparatuses 6 are respectively inserted into both end portions of a main tube 1, and the main tube 1 is held by connecting a chip pipe 4 to an inert gas leading-in pipe 5. Then, after flowing inert gas 7 into the main tube 1 from the leading-in pipe 5 through the chip pipe 4, moisture and impure gas in the main tube 1 are discharged by heating the whole main tube 1 below a melting temperature through a process divided into 2 or more heating steps with a gas burner. After that, electrodes 2, 3 on both end portions of the main tube 1 are sealed at the same time with press heads 9, 9 having concave portions corresponding to a luminous portion, and the luminous portion of a luminous tube is formed by pressing at the same time. Thereby, it is attempted to reduce the number of working processes and working time, and also to improve the yield for forming the luminous portion. |
