LAMP WITH MULTI-LAYER PHOSPHOR COATING

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A lamp envelope is provided with an alumina layer and a multilayer phosphor coating on the alumina layer. The phosphor coating includes a top phosphor layer with a first weight percent of rare earth activators and a middle phosphor layer with a second weight percent of rare earth activators. The second weight percent is less than the first weight percent so that a total amount of the activators in the coating is reduced while maintaining a required lamp brightness and color rendering index (CRI). Preferably, the second weight percent is about 50-60% of the first weight percent and the middle layer is about 30-50% of a total weight of the coating so that a total weight of the activators in the coating is no more than about 80% of a weight of the activators in the coating if the first and second weight percents were the same.