Luminescent material for low-pressure mercury-vapour discharge lamps

摘要

The invention relates to luminescent materials for mercury-vapour discharge lamps of improved long-term stability. Materials used as luminescent materials are those where the electronegativity of the elements forming the central ions of the anions or of the elements which act as cations in the acid-forming oxides is between the limits of 1.1 and 2.2; the luminescent material has, after irradiation for 5 hours at a temperature of between 20 DEG C and 200 DEG C in vacuum at a pressure smaller than 1 Pa or in inert gases, preferably argon, at a pressure of 100 Pa up to 101 kPa with a UV radiator which predominantly emits radiation of the energies 6.71 eV and 4.89 eV at a power ratio (efficiency ratio) of the resonance lines from 0.16 up to 1.0, the irradiance (exposure rate) of the layer of luminescent material being between 50 and 500 W/m<2>, a radiation power per unit area and solid angle which is lower by at most 30% (vacuum) or at most 20% (argon) than the unirradiated luminescent material on excitation at 4.89 eV irradiation of a UV radiator, the irradiated luminescent material, after secondary irradiation carried out in an oxygen-containing atmosphere with the same radiation source and the same irradiance as in the first irradiation, partly or totally regenerated its emission capability and, after 5 hours of action of 4.89 eV radiation of a UV radiator in argon atmosphere at an irradiance of the luminescent-material layer between 50 and 500 W/m<2> a decrease in the luminescence of ... Original abstract incomplete.