Fluorescent lamp utilizing phosphor combination
AssigneeGeneral Electric Company
InventorWilliam W. Piper
Life of this patent
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Abstract
A fluorescent lamp construction is described utilizing a particular combination of two different phosphor materials in order to produce more efficient emission of white color light and whose color temperature can be controlled. The particular phosphor combination can be utilized as a blended mixture; and the color point of the lamp emission can be adjusted to approximate black body radiation emission such as incandescent lamp emission with negligible loss in optimum luminous efficacy.
Claims8
In a high pressure mercury vapor type fluorescent lamp having an evacuable light transmissive envelope coated with phosphor, a gaseous medium containing mercury vapor within said envelope which can be excited by an electromagnetic field at a very high discharge power density to produce a mercury vapor pressure in excess of 7 millitorr and emit ultraviolet radiation as well as visible radiation of an overall blue color, said visible radiation constituting at least 25% of the total visible lamp emission, the improvement which comprises using a blended mixture comprising a europium activated rare earth oxide phosphor with a second phosphor having a narrow principal emission band with a mean wavelength in the green portion of the spectrum between the wavelengths of 525 and 570 nanometers, said phosphor combination producing composite lamp emission of a white color when exposed directly to said gaseous medium.
Dependencies are inferred from the claim text.