Backlight having a waveguide with a plurality of extraction facets, array of light sources, a rear reflector having reflective facets and a transmissive sheet disposed between the waveguide and reflector
First Claim
1. A directional backlight comprising:
- a waveguide comprising first and second, opposed guide surfaces for guiding light along the waveguide, an input surface extending between the first and second guide surfaces for receiving input light, and a reflective end for reflecting input light from the light sources back along the waveguide;
an array of light sources arranged at different input positions along the input surface of the waveguide and arranged to input the input light into the waveguide,wherein the first guide surface is arranged to guide light by total internal reflection and the second guide surface has a stepped shape comprising a plurality of extraction facets oriented to reflect input light from the light sources, after reflection from the reflective end, through the first guide surface as output light, and intermediate regions between the facets that are arranged to guide light along the waveguide, the waveguide being arranged to image the light sources so that the output light is directed into respective optical windows in output directions that are distributed laterally in dependence on the input positions of the light sources;
a rear reflector comprising a linear array of reflective facets arranged to reflect light from the light sources, that is transmitted through the plurality of facets of the waveguide, back through the waveguide to exit through the first guide surface; and
a transmissive sheet arranged between the rear reflector and the second guide surface of the waveguide.
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Accused Products
Abstract
An imaging directional backlight apparatus includes a waveguide and light source array for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure in which steps may include extraction features optically hidden to guided light, propagating in a forward direction. Returning light propagating in a backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Viewing windows are formed through imaging individual light sources and defines the relative positions of system elements and ray paths. Alignment of the waveguide to mechanical and optical components may be provided by surface relief features of the waveguide arranged in regions adjacent the input surface and intermediate the light emitting regions of the light sources. Efficient, uniform operation may be achieved with low cross talk for application to autostereoscopic and privacy modes of operation.
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Citations
11 Claims
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1. A directional backlight comprising:
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a waveguide comprising first and second, opposed guide surfaces for guiding light along the waveguide, an input surface extending between the first and second guide surfaces for receiving input light, and a reflective end for reflecting input light from the light sources back along the waveguide; an array of light sources arranged at different input positions along the input surface of the waveguide and arranged to input the input light into the waveguide, wherein the first guide surface is arranged to guide light by total internal reflection and the second guide surface has a stepped shape comprising a plurality of extraction facets oriented to reflect input light from the light sources, after reflection from the reflective end, through the first guide surface as output light, and intermediate regions between the facets that are arranged to guide light along the waveguide, the waveguide being arranged to image the light sources so that the output light is directed into respective optical windows in output directions that are distributed laterally in dependence on the input positions of the light sources; a rear reflector comprising a linear array of reflective facets arranged to reflect light from the light sources, that is transmitted through the plurality of facets of the waveguide, back through the waveguide to exit through the first guide surface; and a transmissive sheet arranged between the rear reflector and the second guide surface of the waveguide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification