Light input for directional backlight
First Claim
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1. A directional backlight comprising:
- a waveguide comprising first and second, opposed guide surfaces for guiding input light along the waveguide, wherein the second guide surface comprises at least two parts each extending partway along the waveguide, being separated perpendicular to a lateral direction by an input aperture; and
an array of light sources arranged to generate input light and to inject the input light through the input aperture into the waveguide at respective input positions in the lateral direction across the waveguide, whereinthe waveguide further comprises a reflective end arranged to reflect the input light back through the waveguide to each of the parts of the second guide surface,the first guide surface is arranged to guide light by total internal reflection,each of parts of the second guide surface comprises a plurality of light extraction features that extend linearly and parallel to each other and intermediate regions between the light extraction features that are arranged to direct light through the waveguide without extracting it, the light extraction features being oriented to deflect the input light after reflection from the reflective end in directions allowing exit through the first guide surface as output light through the first guide surface, andthe reflective end has positive optical power in the lateral direction so that the waveguide directs the output light from the light sources into optical windows in output directions that are positioned in the lateral direction in dependence on the input position of the input light.
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Abstract
A directional backlight may include a light guiding apparatus including at least one transparent optical waveguide for providing large area collimated illumination from localized light sources. The waveguide is arranged in a first part and a second part with a light injection aperture between the respective parts. Such controlled illumination may provide for efficient, multi-user autostereoscopic displays as well as improved 2D display functionality including high brightness displays and high display efficiency.
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Citations
25 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 input light along the waveguide, wherein the second guide surface comprises at least two parts each extending partway along the waveguide, being separated perpendicular to a lateral direction by an input aperture; and an array of light sources arranged to generate input light and to inject the input light through the input aperture into the waveguide at respective input positions in the lateral direction across the waveguide, wherein the waveguide further comprises a reflective end arranged to reflect the input light back through the waveguide to each of the parts of the second guide surface, the first guide surface is arranged to guide light by total internal reflection, each of parts of the second guide surface comprises a plurality of light extraction features that extend linearly and parallel to each other and intermediate regions between the light extraction features that are arranged to direct light through the waveguide without extracting it, the light extraction features being oriented to deflect the input light after reflection from the reflective end in directions allowing exit through the first guide surface as output light through the first guide surface, and the reflective end has positive optical power in the lateral direction so that the waveguide directs the output light from the light sources into optical windows in output directions that are positioned in the lateral direction in dependence on the input position of the input light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification