Wide angle imaging directional backlights
First Claim
1. A directional backlight comprising:
- a waveguide comprising an input end;
an array of input light sources arranged at different input positions in a lateral direction across the input end of the waveguide and arranged to input input light into the waveguide,the waveguide further comprising first and second opposed, laterally extending guide surfaces for guiding light along the waveguide, side surfaces extending between the first and second guide surfaces, and a reflective end facing the input end for reflecting the input light back along the waveguide and having positive optical power laterally, the second guide surface being arranged to deflect the reflected input light through the first guide surface as output light, and the waveguide being arranged to direct the output light into optical windows in output directions that are distributed in a lateral direction in dependence on the input position of the input light; and
additional light sources arranged to direct additional light into the waveguide in a direction in which the additional light is reflected by the reflective end onto the opposite side surface and by the opposite side surface into a segment of the waveguide adjacent the opposite side surface extending from a corner between the reflective surface and the side surface.
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Accused Products
Abstract
An imaging directional backlight apparatus including a waveguide, a light source array, for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, in which the steps may further include extraction features optically hidden to guided light, propagating in a first forward direction. Returning light propagating in a second 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 hence defines the relative positions of system elements and ray paths. Lateral non-uniformities of output image are improved by means of adjustment of input aperture shape and reflective aperture shape. Cross talk in autostereoscopic and privacy displays may further be improved by light blocking layers arranged on the input end of the waveguide.
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Citations
19 Claims
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1. A directional backlight comprising:
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a waveguide comprising an input end; an array of input light sources arranged at different input positions in a lateral direction across the input end of the waveguide and arranged to input input light into the waveguide, the waveguide further comprising first and second opposed, laterally extending guide surfaces for guiding light along the waveguide, side surfaces extending between the first and second guide surfaces, and a reflective end facing the input end for reflecting the input light back along the waveguide and having positive optical power laterally, the second guide surface being arranged to deflect the reflected input light through the first guide surface as output light, and the waveguide being arranged to direct the output light into optical windows in output directions that are distributed in a lateral direction in dependence on the input position of the input light; and additional light sources arranged to direct additional light into the waveguide in a direction in which the additional light is reflected by the reflective end onto the opposite side surface and by the opposite side surface into a segment of the waveguide adjacent the opposite side surface extending from a corner between the reflective surface and the side surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification