| 摘要 |
PROBLEM TO BE SOLVED: To efficiently produce a lamp arc tube with high quality and having no variations in outside dimension, internal volume, wall-thickness distribution, etc. of a light emitting part by using a thin glass tube material with large wall thickness. SOLUTION: While rotating the glass tube material 20 around a tube axis, its intermediate part is heated and softened with a burner 22. Pressurized gas is introduced from both ends of the glass tube material 20 so that the inside of the tube is in a positive pressure state. On or after diametrically expanding the intermediate part which is heated and softened, while mutually approximating the ends of the glass tube material 20, the intermediate part is expanded to form swelling 23 which serves as a light emitting part. COPYRIGHT: (C)2006,JPO&NCIPI
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