Cool-white fluorescent lamp with phosphor having modified spectral energy distribution to improve luminosity thereof
AssigneeGeneral Electric Company
InventorsWilliam W. Piper, Jerome S. Prener, George R. Gillooly
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Abstract
An improved cool-white fluorescent lamp utilizes a particular two-component phosphor combination exhibiting a narrow "blue" emission spectrum and a broad "yellow" emission spectrum to achieve improved luminous efficacy. In one preferred embodiment, the combination is a blended mixture of europium activated strontium chlorapatite with manganese and antimony coactivated calcium fluorapatite phosphors.
Claims8
In a fluorescent lamp of the type having a sealed envelope enclosing means to generate a low-pressure mercury discharge within said envelope, and a coating contained within said envelope for conversion of at least a portion of the radiation emitted from said discharge to visible light having a white color, the improved coating comprising:
- a first phosphor having a relatively broad emission spectrum with a mean wavelength in a yellow portion of the visible spectrum, wherein said first phosphor is Ca.sub.10-w-x-y Cd.sub.w Mn.sub.x Sb.sub.y (PO.sub.4).sub.6 F.sub.2-y O.sub.y where w is in the approximate range 0.0-0.2, x is in the approximate range 0.25-0.50 and y is in the approximate range 0.02-0.2;
- a second phosphor having a relatively narrow emission spectrum in a blue portion of the visible spectrum;
- said first and second phosphors being uniformly blended together in a porportional relationship preselected to provide increased luminous efficacy for said mixture.
Dependencies are inferred from the claim text.