Abstract An improved luminescent combination wherein the emissions of distinct luminescent materials are blended to provide a predetermined spectral energy distribution for the combination. When one of the blend constituents is particularly expensive, the requisite amount of this material can be substantially reduced by providing a plurality of luminescent layers with the expensive material being disposed as the layer nearest the source of ultraviolet radiations. This increases the absorption of ultraviolet radiations by this expensive material and its corresponding emission. The desired spectral energy distribution for the combination can be provided with substantially less of the most expensive luminescent material.
The combination as specified in claim 1, wherein the combination comprises a conventional elongated, tubular, low-pressure, mercury discharge lamp, and wherein said plurality of distinct luminescent layers is disposed on the interior surface of the envelope of the lamp.
Claim 2
Dependent Claim
43 words
The combination as specified in claim 1, wherein said combination coMprises a conventional elongated, tubular, high-pressure, mercury discharge lamp enclosed within a bulbous outer envelope, and wherein said plurality of distinct luminescent layers is disposed on the interior surface of said outer envelope.
Claim 3
Dependent Claim
46 words
The combination as specified in claim 1, wherein said base layer of less expensive luminescent composition comprises a blend of predetermined amounts of strontium-magnesium phosphate, tin-activated, strontium blue halophosphate and zinc silicate, manganese activated, and said other layer of more expensive luminescent composition comprises yttrium-europium oxide.
Claim 4
Dependent Claim
42 words
The combination as specified in claim 1, wherein said base layer of less expensive luminescent composition comprises a blend of predetermined amounts of manganese activated zinc orthosilicate and calcium tungstate, and said other layer of more expensive luminescent composition comprises yttrium-europium oxide.
Claim 5
Dependent Claim
27 words
The combination as specified in claim 4, wherein the weight ratios of said strontium-magnesium phosphate, said halophosphate, said silicate, and said yttrium-europium oxide are about 41:55:2: 2.
Claim 6
Dependent Claim
23 words
The combination as specified in claim 5, wherein the weight ratios of said orthosilicate, said tungstate and said yttrium-europium oxide are about 1.77:0.92:0.77.