| 摘要 |
A low-pressure mercury vapour discharge lamp particularly for "sun tanning" purposes comprises a discharge vessel containing mercury and an inert gas and, on the vessel walls, a first fluorescent layer of eg Barium disilicate activated with lead, or Strontium fluoroborate activated with europium exhibiting an emission maximum in the UV/A (315 to 400nm) range and a second fluorescent layer of eg Strontium aluminate activated with cerium, or Calcium orthophosphate actived with thallium exhibiting an emission maximum in the UV/B range (280 to 315 nm). UV/A to UV/B radiation ratios from 10:1 to 100:1 are recommended, the radiation output being influenced by the transmissivity of the lamp glass. Advantageously the UV/A to UV/B radio is approximately 50:1 with 18% glass transmission at 300 nm. A typical spectrum of the invention, Fig. 2 curve a, is compared with that, Fig. 2 curve b of a lamp emitting substantially only in the UV/A region. The mixture of radiations is said to promote faster tanning. <IMAGE> |
