| 摘要 |
<p>A metallic vapor discharge lamp which has an outer tube sealed with a predetermined gas therein, and a light-emitting tube including a pair of electrodes mounted in the tube and provided in the discharge space formed therein, with at least a rare gas and mercury sealed into the discharge space, wherein a lower light transmission cover is provided in the vicinity of the end at the lower position of the end of the light-emitting tube, covering at least the lower end of the light emitting tube when it is alight. In this manner, the temperature-reducing action of the lower part of the light-emitting tube due to convection in the gas in the outer tube can be suppressed, thereby increasing the temperature of the coldest part of the light-emitting tube to increase the vapor pressure in the light-emitting tube suitably, and thereby improve the efficiency of the lamp.</p> |
