| abstract |
A low-pressure mercury vapor discharge lamp has a light-transmitting discharge vessel ( 10 ) enclosing, in a gastight manner, a discharge space ( 13 ) provided with a filling of mercury and a rare gas. The discharge vessel comprises discharge means for maintaining a discharge in the discharge space. The discharge vessel is provided with a luminescent layer ( 17 ) comprising a mixture of at least a red and a green luminescent material. The red luminescent material comprises (Y,Gd) 2 O 3 :Eu. The green luminescent material comprises (Ba,Ca,Sr) 2 SiO 4 :Eu and/or (Sr,Ca,Ba,Mg,Zn)Si 2 N 2 O 2 :Eu. Particles of the green luminescent material are surrounded by a coating of aluminum oxide. Preferably, at least 50% of the particles of the green and red luminescent materials have an average diameter greater than or equal to approximately 5 μm. The mixture of the red and green luminescent materials render a low-pressure mercury-vapor discharge lamp with an improved lumen equivalent. |