HIGH COLOR RENDERING HIGH-PRESSURE SODIUM LAMP

摘要

PROBLEM TO BE SOLVED: To provide a high color rendering high-pressure sodium lamp with a light color close to an incandescent lamp by preventing a luminescent color from being seen as green, and by positioning the chromaticity point of the luminescent color in the vicinity of a black-body locus. SOLUTION: Conductive tube 2 and 3 are provided on both ends of an arc tube 1 and are sealed tightly with the arc tube 1 by frits 4 and 5. Electrodes 6 and 7 are held in the conductive tubes 2 and 3. The tube wall load of the arc tube 1 is 39.5W/cm<2> and metallic sodium 3mg and xenon gas 4×10<4> Pa (25 deg.C) are filled in the arc tube 1. The arc tube 1 is held in an outer tube 9, which is filled with gaseous nitrogen 2.7×10<4> Pa. A proximity conductor 10 is attached along the outer wall of the arc tube 1 to facilitate starting by applying electric potential. A getter 11 is provided to adsorb hydrogen in the outer tube 9 and to control the rise of starting voltage, and 12 is a base.