Abstract: Mercury vapor discharge lamp, in particular low pressure mercury vapor discharge lamp, for color copying by electrophotographic processes, which lamp has a luminescent layer which emits in a band in the blue part, in a band in the green part and in a band in the red part of the spectrum. The luminescent layer comprises two luminescent materials the first of which emits both in the said blue part and in the said green part of the spectrum, while the second emits in the said red part of the spectrum.

Abstract: A low-pressure mercury vapour discharge lamp provided with a luminescent coating comprising three luminescent materials each emitting in a narrow spectral range. The first material has an emission band with a maximum between 430 and 490 nm; the second material has its emission in the range 520-565 nm; the third material emits in the range 590-630 nm. The second material is defined by one of the formulas:A. Ce.sub.1-x-y La.sub.x Tb.sub.y MgAl.sub.11 O.sub.19b. (Ce.sub.1-x-y La.sub.x Tb.sub.y).sub.2 O.sub.3.nAl.sub.2 O.sub.3The first material is preferably chosen fromC. A.sub.1-p Eu.sub.p Mg.sub.2-q Mn.sub.q Al.sub.16 O.sub.27d. B.sub.5.5-x Eu.sub.x Mg.sub.6-y Mn.sub.y Al.sub.55 O.sub.94(a and B are barium and/or strontium).