Fluorescent lamp using low press. mercury vapour discharge - and mixt. of two luminophors on lamp tube to increase luminous efficiency

摘要

Fluorescent lamp using a sealed bulb or tube for a low press. Hg discharge; in the tube is a coating converting at least part of the radiation into visible light with a cold-white spectrum. The coating contains a luminophore (1) with a broad emission spectrum and average wavelength in the yellow part of the visible spectrum; plus a second luminophore (2) with a narrow emission spectrum in a blue part of the visible range; the luminophors (1,2) are mixed together to obtain high luminous efficiency. (1) is pref. Ca10-w-x-yCdwMnxSby(PO4)6F2-yOy, (where w = 0-0.2; x = 0.25-0.5; y = 0.02-0.2) with peak emission 570-300 nm. (2) is pref. Sr10-zEuz(PO4)6Cl2, (where z = 0.02-0.2), with peak emission 450 nm. The amt. of (2) in the mixt. (1,2) pref. results in an emission spectrum for (1) which has a cold-white colour point with trichromatic coordinates X = 0.377 and Y = 0.382; the amt. of Mn in (1) can be varied to reach the colour point. A 5-10% increase in luminous efficiency is obtd., e.g. in a 36 watt lamp.