| 摘要 |
PURPOSE:To prevent generation of dispersion of the phosphor film end part positions or of the wrincles of the phosphor film by forming a concave part extending in the circumferential direction in a ring shape on the end part of a glass tube followed by applying phosphor coating varnish to the inner peripheral surface of the glass tube and thereafter sealing a stem on the end part of the glass tube. CONSTITUTION:A ring-shaped concave part 2 winding about the outer periphery is formed in a prescribed position from the end part of a glass tube. After the molding of the concave part 2 is finished, phosphor coating varnish is applied to the inside of the glass tube 1 for forming a phosphor film 3 while wiping out the phosphor film 3 up to a position in a prescribed distance from the tube end of the glass tube 1, for instance, up to the center position of the concave part. Next, after inserting a stem 4 up to a position in a prescribed distance from the center of the concave part 2 in the glass tube, for instance, up to the position in the distance of l2, the glass tube 1 and the stem 4 are sealed. |
