| 摘要 |
<p>High-pressure sodium vapor discharge lamps having a color temperature of 2250 to 2750 K. and a color rendition index Ra of 60-85 emit light of a strongly reduced Ra already after approximately 2000 hours in operation. As compared with the life of normal, yellow high-pressure sodium vapor discharge lamps, this period is very short. The discharge vessel contains sodium, mercury and a rare gas, the weight ratio Na/Hg being from 1/1 to 1/9 and the sodium pressure during operation of the lamp being from 4x104 to 10.7x104 Pa. The rare gas pressure in the discharge vessel at 300 K. is between 1333 and 1333x102 Pa. By using an emitter which contains oxygen-bound strontium and oxygen-bound tungsten in a molar ratio from 3/1 to 50/1, the initial properties of such white-light-producing lamps are maintained for a long period of time.</p> |
