Thin Backlight Using Low Profile Side Emitting LEDs
First Claim
1. A light emitting device comprising:
- at least one side-emitting, non-lasing light emitting diode (LED), wherein a majority of light emitted normal to a top surface of a semiconductor LED die is redirected away from the normal; and
a lightguide having an output surface through which light is emitted,the lightguide having at least one indention in a first surface, opposite the output surface, wherein each indention contains a side-emitting LED, walls of the indention forming part of the first surface,the lightguide having optical features on at least one of the output surface and the first surface for limiting an appearance of dark areas over each LED or bright areas proximate to each LED, the optical features redirecting light to improve a uniformity of brightness across the output surface of the lightguide.
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Accused Products
Abstract
Backlights containing low profile, side-emitting LEDs are described that have improved brightness uniformity. In one embodiment, the backlight comprises a solid transparent lightguide with a plurality of openings in a bottom surface of the lightguide, each opening containing a side-emitting LED. Prisms or other optical features are formed in the top wall of each opening to reflect light in the lightguide towards a light output surface of the lightguide so that the side-emitting LEDs do not appear as dark spots at the output of the backlight. To avoid any direct emission from the sides of the LED toward the output surface of the lightguide appearing as bright areas, optical features are formed at the edges of the opening or in the output surface of the lightguide so that direct emission light is not output from the lightguide. Substantially identical cells may be formed in the lightguide using cellular walls around one or more LEDs.
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Citations
40 Claims
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1. A light emitting device comprising:
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at least one side-emitting, non-lasing light emitting diode (LED), wherein a majority of light emitted normal to a top surface of a semiconductor LED die is redirected away from the normal; and a lightguide having an output surface through which light is emitted, the lightguide having at least one indention in a first surface, opposite the output surface, wherein each indention contains a side-emitting LED, walls of the indention forming part of the first surface, the lightguide having optical features on at least one of the output surface and the first surface for limiting an appearance of dark areas over each LED or bright areas proximate to each LED, the optical features redirecting light to improve a uniformity of brightness across the output surface of the lightguide. - 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, 26, 27, 28)
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29. A light emitting device comprising:
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a plurality of side-emitting, non-lasing light emitting diodes (LED); a lightguide having an output surface through which light is emitted, each LED being positioned within an opening in the lightguide so as to optically couple light into the lightguide; and cellular walls within the lightguide at least partially surrounding one or more LEDs, each cellular wall being at least partially reflective, wherein the cellular walls create a plurality of cells in the lightguide, a light output from each cell being substantially the same. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification