Light source utilizing reflective cavity having sloped side surfaces
First Claim
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1. An apparatus comprising:
- a display having a rear surface and a front surface, said display panel being at least partially transmissive such that at least a portion of illumination on said rear surface is transmitted to said front surface;
a light source for backlighting said display panel, said light source comprising;
a device that emits light;
a housing having diffusive reflective interior surfaces forming a cavity, said cavity having a depth, said light emitting device mounted in said cavity, said housing having an aperture which opens into said cavity, said aperture juxtaposed with said rear surface of said display panel to illuminate said rear surface, said cavity having a diffusive reflective surface area and said aperture having an area, the ratio of said area of said aperture to the sum of (i) said area of said aperture and (ii) said surface area of said cavity being at least 0.05, said aperture having an edge to edge dimension, the ratio of said depth to said edge-to-edge dimension being at least 0.1;
a diffuser at said aperture, said diffuser positioned to diffuse illumination which passes through said aperture from said cavity toward said display panel;
a brightness enhancing material disposed between said diffuser and said display panel, said material concentrating illumination within a viewing angle so as to enhance the brightness of the display panel.
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Abstract
A light source for backlighting a display comprises a light-emitting device such as an incandescent bulb or LED array disposed within a cavity having diffusely reflecting walls and an aperture. A diffuser and brightness enhancing film are situated at the opening of the aperture between the aperture and the display to be backlit. A color filter may also be employed to whiten the light emerging from the light source.
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Citations
18 Claims
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1. An apparatus comprising:
a display having a rear surface and a front surface, said display panel being at least partially transmissive such that at least a portion of illumination on said rear surface is transmitted to said front surface;
a light source for backlighting said display panel, said light source comprising;
a device that emits light;
a housing having diffusive reflective interior surfaces forming a cavity, said cavity having a depth, said light emitting device mounted in said cavity, said housing having an aperture which opens into said cavity, said aperture juxtaposed with said rear surface of said display panel to illuminate said rear surface, said cavity having a diffusive reflective surface area and said aperture having an area, the ratio of said area of said aperture to the sum of (i) said area of said aperture and (ii) said surface area of said cavity being at least 0.05, said aperture having an edge to edge dimension, the ratio of said depth to said edge-to-edge dimension being at least 0.1;
a diffuser at said aperture, said diffuser positioned to diffuse illumination which passes through said aperture from said cavity toward said display panel;
a brightness enhancing material disposed between said diffuser and said display panel, said material concentrating illumination within a viewing angle so as to enhance the brightness of the display panel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of backlighting a display panel, comprising:
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producing illumination from a substantially lambertian light source comprising a cavity with internal walls and an aperture, said step of producing illumination comprising the step of directing light rays from the perimeter of the aperture into the cavity such that the light exiting the aperture is substantially uniform in intensity and color;
using a diffuser to diffuse light from said substantially lambertian light source;
using a brightness enhancing film to concentrate the diffused light into a predetermined angular range without significantly reducing the uniformity of the diffused light; and
directing the concentrated, diffused light onto said display panel. - View Dependent Claims (18)
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Specification