| 摘要 |
PURPOSE:To prevent occurrence of ''pitting'' in the tubular body of fluorescent lamp, by air-cooling the central portion of a rapid-start type fluorescent lamp. CONSTITUTION:In a rapid-start type fluorescent lamp, in which a transparent conductive film 2 principally made of tin oxide is formed on the inner surface of bulb 1 and fluorescent material 3 is coated on the film 2, the lowest temperature points where condensation of mercury is promoted is located at the portions 10 to 30 % bulb length from both ends of the bulb 1, and minute discharge is caused between the condensed mercury and said conductive film 2, ao that there is caused dark ''pitting'' 5 due to rupture, discoloration or other of the fluorescent material 3. In order to prevent such ''pitting'', cool air supplying ports 7 connected to air condioning duct 12 are opened at the central portion of lithting apparatus 6, and cool air is blown out downwards of the lighting apparatus 6 by the aid of covers 6a on both sides of the same, to forcibly cool the bulb 1. With such an arrangement, central portion of the bulb 1 is cooled effctively, so that any discharge is not caused between said film 2 and condensed mercury, if condensation of merucry is caused, since almost no potential difference between the film 2 and Hg gas. Thus, occurrence of pitting of the bulb 1 can be positively prevented. |
