US 11,668,975 B2
Edge-lit back light unit with improved efficiency
Kenneth L. Walker, Semora, NC (US); Bing A. Shen, Durham, NC (US); and Matthew K. Pope, Durham, NC (US)
Assigned to BrightView Technologies, Inc., Durham, NC (US)
Filed by BrightView Technologies, Inc., Durham, NC (US)
Filed on Dec. 16, 2021, as Appl. No. 17/553,170.
Claims priority of provisional application 63/214,730, filed on Jun. 24, 2021.
Claims priority of provisional application 63/127,325, filed on Dec. 18, 2020.
Prior Publication US 2022/0197086 A1, Jun. 23, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. G02F 1/13357 (2006.01); F21V 8/00 (2006.01); G02F 1/1335 (2006.01)
CPC G02F 1/133603 (2013.01) [G02B 6/0011 (2013.01); G02F 1/133524 (2013.01); G02F 1/133607 (2021.01); G02F 1/133615 (2013.01)] 37 Claims
OG exemplary drawing
 
1. An edge-lit back light unit for a backlit display, the edge-lit back light unit comprising:
a specular reflector;
an edge-lit light guide film positioned above the specular reflector, the edge-lit light guide film having a length and a width, wherein a combination of the edge-lit light guide film and the specular reflector is configured to provide a peak optical distribution of 15° to 20° and a full width half maximum angle of diffusion of 25° to 45°;
a diffuser film positioned above the edge-lit light guide film, the diffuser film having a plurality of parallel prism microstructures on one side thereof facing the edge-lit light guide film, at least some of the plurality of parallel prism microstructures having an apex angle of 78° to 92° and being formed of a material having a refractive index of 1.49 to 1.58, and a plurality of diffuser microstructures on an opposite side thereof, the diffuser microstructures having a full width half maximum angle of diffusion of 30° to 60°; and
a pair of crossed brightness enhancement films positioned above the diffuser film, at least one of the brightness enhancement films having a plurality of parallel micro prisms on one side thereof and facing away from the diffuser film, wherein the plurality of parallel micro prisms of one of the brightness enhancement films is oriented perpendicular to the plurality of micro prisms of the other brightness enhancement film,
wherein the plurality of prism microstructures of the diffuser film is substantially aligned with the plurality of parallel micro prisms of at least one of the brightness enhancement films.