| 摘要 |
PURPOSE:To improve luminous flux maintainability by forming a film, which is made of calcium barium borate as a main ingredient, on an inner surface of a glass tube and forming a phosphor film thereon. CONSTITUTION:A film 3, which is made of calcium barium borate as a main ingredient, is formed as a first layer on an inner surface of a glass tube 2 of a crooked fluorescent lamp 1, and a phosphor film 4 is formed thereon. The calcium, barium borate is made glassy by a heating temperature when the glass tube 2 is crookedly formed so as to be strongly sticked on the inner surface of the glass tube, and it is strongly sticked also on the phosphor film 4 so that the phosphor film 4 is prevented from being peeled when the lamp is crookedly formed. Hence, coloring or so of a glass tube wall, which is caused by ultraviolet radiation and invasion.diffusion of mercury ions, can be suppressed to improve luminous flux maintainability during its life.
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