| 摘要 |
<p>37 A low-pressure mercury vapour discharge lamp having a very satisfactory colour rendition, (R(a,8)?85), a colour temperature of 2300-3300 K and a colour point on or near the Planckian curve. Besides a very satisfactory colour rendition at a low colour temperature, these lamps have a high luminous flux and a high maintenance of the luminous flux during their life. The lamp is provided with a luminescent layer comprising: a. a luminescent alkaline earth metal halophosphate activated by Sb3+ and Mn2+ having a colour temperature of 2900-5000 K; b. a luminescent material activated by Eu2+ with an emission maximum in the range of 470-500 nm and a halfvalue width of at most 90 nm, and c. a luminescent rare earth metal metaborate activated by Ce3+ and Mn2+, having a fundamental lattice Ln(Mg,Zn,Cd) B5O10, in which Ln represents the elements Y, La and/or Gd, which borate has red Mn2+ emission and the lamp is further provided with means for absorbing blue radiation having wavelengths below 480 nm. Preferably, the luminescent layer further contains: d. a luminescent material activated by Tb3+ which exhibits green Tb3+ emission.</p> |
