Polarized diffractive backlight
First Claim
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1. A lightguide for distributing light received from a light source, comprising:
- a lightguide substrate having first and second major faces and an edge face there between into which light from the light source is injected, the lightguide substrate being configured to transfer the light between the first and second major faces by total internal reflection; and
an extraction feature structure on at least one of the first and second major faces of the lightguide substrate to extract the light from the lightguide substrate, the extraction feature structure including at least a first grating interleaved with a second grating, wherein a spatial frequency of the first grating is different than that of the second grating,wherein the spatial frequency of the first grating is substantially twice that of the second grating.
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Abstract
A backlight is provided for illuminating an at least partially transmissive display. The backlight includes a light source. A light guide receives the light from an edge surface and guides the light by total internal reflection. The light is extracted from the lightguide using sub-wavelength extraction features designed on the basis of two interleaved grating structures. The emitted light, using this arrangement has a high level of polarization.
43 Citations
19 Claims
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1. A lightguide for distributing light received from a light source, comprising:
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a lightguide substrate having first and second major faces and an edge face there between into which light from the light source is injected, the lightguide substrate being configured to transfer the light between the first and second major faces by total internal reflection; and an extraction feature structure on at least one of the first and second major faces of the lightguide substrate to extract the light from the lightguide substrate, the extraction feature structure including at least a first grating interleaved with a second grating, wherein a spatial frequency of the first grating is different than that of the second grating, wherein the spatial frequency of the first grating is substantially twice that of the second grating. - View Dependent Claims (2, 3, 4, 5, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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6. A lightguide for distributing light received from a light source, comprising:
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a lightguide substrate having first and second major faces and an edge face there between into which light from the light source is injected, the lightguide substrate being configured to transfer the light between the first and second major faces by total internal reflection; and an extraction feature structure on at least one of the first and second major faces of the lightguide substrate to extract the light from the lightguide substrate, the extraction feature structure including at least a first grating interleaved with a second grating, wherein a spatial frequency of the first grating is different than that of the second grating, wherein the first and second gratings are configured such that for a first polarization, light emitted from the first grating interferes destructively with light emitted from the second grating and is reflected back into the lightguide substrate. - View Dependent Claims (7)
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9. A lightguide for distributing light received from a light source, comprising:
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a lightguide substrate having first and second major faces and an edge face there between into which light from the light source is injected, the lightguide substrate being configured to transfer the light between the first and second major faces by total internal reflection; and an extraction feature structure on at least one of the first and second major faces of the lightguide substrate to extract the light from the lightguide substrate, the extraction feature structure including at least a first crating interleaved with a second grating, wherein a spatial frequency of the first crating is different than that of the second grating, the extraction feature structure further comprising at least a third grating interleaved with the first and second gratings, wherein a spatial frequency of the third grating is an integer multiple of the spatial frequency of the first grating.
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Specification