| 摘要 |
PROBLEM TO BE SOLVED: To suppress inner temperature-rise of a lighting circuit part, and reduce thermal load to circuit elements by carrying out cooling through a natural ventilation in a lamp housing by air temperature differences in the inside and the outside of the lamp housing. SOLUTION: This is constituted so that the first opening part 2d to be opened to face a housing space K of a lighting circuit part surrounded by the rear face 3f of a reflector 3 and the lamp housing 2 and to be positioned more downwardly than a lighting control circuit 8 does and the second opening part 2d to be opened to face the housing space K of the lighting circuit part in the samer manner and to be positioned more upwardly than the lighting control circuit 8 does are installed, so that the natural ventilation of the inside of the housing space K of the lighting circuit part is carried out via these the first and the second opening parts 2d, 2e. As a result of this, the lighting control circuit 8 is cooled by natural convection of air occurring due to temperature differences between the temperature in the housing space K of the lighting circuit part during the lighting of a discharge lamp bulb 4 and the outside air temperature, and the thermal load to the circuit elements can be reduced. |
