Directional backlight
First Claim
Patent Images
1. A directional backlight comprising:
- an array of light sources;
a light expansion waveguide section having an input end and opposed guide surfaces for guiding light along the waveguide, the array of light sources disposed at different input positions in a lateral direction across the input end of the light expansion waveguide section;
a light extraction waveguide section arranged to receive light from the light expansion waveguide section; and
a lens element arranged between the light expansion waveguide section and the light extraction waveguide section, the lens element having positive optical power in the lateral direction,wherein the light extraction waveguide section comprises first and second opposed guide surfaces for guiding light along the light extraction waveguide section, the first guide surface being arranged to guide light by total internal reflection and the second guide surface having a stepped shape comprising a plurality of facets and intermediate regions intermediate the facets, whereinthe intermediate regions are arranged to direct light through the light extraction waveguide section without extracting it, andthe facets extend in the lateral direction facing the light expansion waveguide section, are oriented to reflect light guided through the light extraction waveguide section in directions allowing exit through the first guide surface, and are curved to provide positive optical power in the lateral direction, the positive optical power in the lateral direction of the lens element and the positive optical power in the lateral direction of the facets being arranged to converge the input light such that the light that exits through the first guide surface is directed into optical windows in output directions distributed in the lateral direction that are dependent on the input positions of the light sources.
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Abstract
Disclosed is an optical inline light guiding apparatus which may include a substantially parallel planar light expansion section and a light extraction section comprising a stepped structure, in which the steps may be extraction features and guiding features. Such controlled illumination may provide for efficient, multi-user autostereoscopic displays with wide viewing freedom, high efficiency and low cross talk and other directional display uses.
334 Citations
14 Claims
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1. A directional backlight comprising:
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an array of light sources; a light expansion waveguide section having an input end and opposed guide surfaces for guiding light along the waveguide, the array of light sources disposed at different input positions in a lateral direction across the input end of the light expansion waveguide section; a light extraction waveguide section arranged to receive light from the light expansion waveguide section; and a lens element arranged between the light expansion waveguide section and the light extraction waveguide section, the lens element having positive optical power in the lateral direction, wherein the light extraction waveguide section comprises first and second opposed guide surfaces for guiding light along the light extraction waveguide section, the first guide surface being arranged to guide light by total internal reflection and the second guide surface having a stepped shape comprising a plurality of facets and intermediate regions intermediate the facets, wherein the intermediate regions are arranged to direct light through the light extraction waveguide section without extracting it, and the facets extend in the lateral direction facing the light expansion waveguide section, are oriented to reflect light guided through the light extraction waveguide section in directions allowing exit through the first guide surface, and are curved to provide positive optical power in the lateral direction, the positive optical power in the lateral direction of the lens element and the positive optical power in the lateral direction of the facets being arranged to converge the input light such that the light that exits through the first guide surface is directed into optical windows in output directions distributed in the lateral direction that are dependent on the input positions of the light sources. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification