Surface-Emission Light Source with Uniform Illumination
AssigneesIfire IP Corporation, Sanyo Electric Co., Ltd.
InventorsJames Alexander Robert Stiles, Hiroki Hamada, Isao Yoshida
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Abstract
An extended area uniform light source providing uniform luminance is taught for displays and other applications where the light emission can be planar or have curvature. The uniform light source is achieved using a combination of a blue light-emitting electroluminescent layer and a highly stable inorganic photoluminescent colour conversion layer to tailor the colour spectrum of the emitted light. The invention thus encompasses the uniform light source, displays incorporating the uniform light sources as well of methods of making such light sources and displays.
Claims28
A light emitting device having a spatially extended surface over which the luminosity of the emitted light at the emission surface is uniform, said device comprising a thick film composite dielectric layer, a blue light-emitting phosphor layer, a photoluminescent film coated over the blue light-emitting phosphor layer, wherein said photoluminescent film permits transmission of only a portion of the blue light to convert to a light of a longer wavelength to provide a light having a defined colour.
A uniform light emitting device comprising, a thick film composite dielectric layer, a barium thioaluminate (BaAl2S4) phosphor layer over said thick film composite, and a yttrium aluminum garnet (YAG) coated over said phosphor layer, wherein said YAG permits transmission of only a portion of the blue light to convert to a light of a longer wavelength to provide a white light having a defined colour temperature.
A method of making a uniform white light source, said method comprising;
- to a thick film composite dielectric layer applying a blue light-emitting phosphor layer;
- coating said blue light-emitting phosphor layer with a semi-transparent photoluminescent film;
- and
- applying an electric field such that said photoluminescent film permits transmission of only a portion of the blue light to convert to a light of a longer wavelength to provide a light having a defined colour.
Dependencies are inferred from the claim text.