| 摘要 |
PURPOSE:To make the phosphor film applied to an inner surface of a bent bulb burnable in a short time, by blowing a combustion improving gaseous body of the phosphor film in a U-shaped bulb from one side of the double end openings. CONSTITUTION:Each passing position of openings (m) and (m) of upper stage straight tube parts 3a and 3a of two U-shaped bulbs 2 and 2 of a bent bulb 1 and openings (n) and (n) of lower stage straight bulb parts 3b and 3b at the inside of a heating furnace 9 is parted to the upper stage. If the passing position of these opening (m) and (m) of the former is set to L1 and the passing position of that of the latter to L2, respectively, a blow pipe 10 is, for example, set up in opposition to the upper end passing position L1 in parallel. This blow pipe 10 is provided with a long-size slit 11 in the front to be opposed to the upper stage passing position L1. And, a combustion improving gaseous body of the phosphor film 7' supplied to the blow pipe 10, for example, air 12 is jetted out of the slit 11, and blown in these openings (m) and (m) of the upper stage straight bulb parts 3b and 3b passing through the upper stage passing position L1. With this constitution, the phosphor film 7' applied to inner surface of the bulb 1 is heated and burned in a short time.
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