| 摘要 |
PURPOSE: To prevent the thermal damage of a lighting circuit component stored in a cover by making the diameter of a member fitted to the opening section of the cover larger than the diameter of the cover. CONSTITUTION: The diameter of a member fitted to the other end opening section of a cover 1, e.g. the diameter of a member 6 supporting a fluorescent lamp 15 or a covering member 18 of the fluorescent lamp 15, is made larger than the diameter of the cover 1. The high-temperature ascending air current generated by the heat emitted from the lamp 15 or the heat emitted from the surface of the covering member 18 of the lamp 15 rises on the periphery apart from the surface of the cover 1. The heat radiation from the surface of the cover 1 is not impeded, the ratio that the ascending air current heats the cover 1 is reduced, and a lighting circuit component can thermally be protected. |
