# US 12,001,097 B2 · Edge-lit back light unit with improved efficiency > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,001,097 B2 - Document ID: US12001097B2 - Status: Granted - Kind: B2 - Application number: 18/310,877 - Filed: 2023-05-02 - Published: 2023-08-31 - Granted: 2024-06-04 - Earliest claimed: 2020-12-18 - Assignees: BrightView Technologies, Inc. - Applicants: BrightView Technologies, Inc. - Inventors: Kenneth L. Walker; Bing Shen; Matthew K. Pope - Web page: https://patentgrep.com/patent/US12001097B2 ## CPC - G02B 6/0053: {Prismatic sheet or layer; Brightness enhancement element, sheet or layer} - G02F 1/133603: {with LEDs} - G02B 6/0011: {the light guides being planar or of plate-like form} - G02B 6/0051: {Diffusing sheet or layer} - G02B 6/0055: {Reflecting element, sheet or layer} - G02F 1/133524: {Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides} - G02F 1/133607: {the light controlling member including light directing or refracting elements, e.g. prisms or lenses} - G02F 1/133615: {Edge-illuminating devices, i.e. illuminating from the side} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract An edge-lit back light unit for a backlit display includes a reflector, an edge-lit light guide film, a diffuser film, and a pair of crossed brightness enhancement films with increased efficiency. The diffuser film has an angular light distribution output that is matched to light acceptance angles of the pair of crossed brightness enhancement films to provide increased on-axis brightness without having to increase power to the edge-lit back light unit. ## Claims ### Claim 1 An edge-lit back light unit for a backlit display, the edge-lit back light unit comprising: a) a specular reflector; b) 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 couple light that is input at a light input edge of the edge-lit light guide film out of the edge-lit light guide film with an angular distribution that is directed away from the light input edge and runs nominally along the length of the edge-lit light guide film; c) 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 and being formed of a material having a refractive index, and a plurality of inverted pyramid microstructures on an opposite side thereof, the inverted pyramid microstructures having an apex angle and being formed of a material having a refractive index; and d) 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. ### Claim 2 (depends on 1) The edge-lit back light unit according to claim 1, wherein the plurality of parallel prism microstructures of the diffuser film is substantially aligned with the plurality of parallel micro prisms of at least one of the pair of brightness enhancement films. ### Claim 3 (depends on 1) The edge-lit back light unit according to claim 1, wherein the at least one of the pair of brightness enhancement films comprises the plurality of parallel micro prisms that is oriented to be most closely aligned with a light direction. ### Claim 4 (depends on 1) The edge-lit back light unit according to claim 1, wherein the at least one of the pair of brightness enhancement films is positioned at a top of the edge-lit back light unit. ### Claim 5 (depends on 1) The edge-lit back light unit according to claim 1, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle of about 110°. ### Claim 6 (depends on 1) The edge-lit back light unit according to claim 1, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle of about 90°. ### Claim 7 (depends on 1) The edge-lit back light unit according to claim 1, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle of about 80°. ### Claim 8 (depends on 1) The edge-lit back light unit according to claim 1, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle between about 78° and 92°. ### Claim 9 (depends on 1) The edge-lit back light unit according to claim 1, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index of at least one of 1.5, 1.57, 1.61, 1.62, 1.63, 1.64, 1.65, or 1.7. ### Claim 10 (depends on 1) The edge-lit back light unit according to claim 1, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.49 and 1.58. ### Claim 11 (depends on 1) The edge-lit back light unit according to claim 1, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.60 to 1.65. ### Claim 12 (depends on 1) The edge-lit back light unit according to claim 1, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.55 to 1.7. ### Claim 13 (depends on 1) The edge-lit back light unit according to claim 1, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.5 to 1.65. ### Claim 14 (depends on 1) The edge-lit back light unit according to claim 1, wherein at least some faces of the inverted pyramid microstructures are aligned to be parallel to the parallel prism microstructures of the diffuser film. ### Claim 15 (depends on 1) The edge-lit back light unit according to claim 1, wherein at least some faces of the inverted pyramid microstructures are aligned to be parallel to the prism microstructures of the diffuser film to within less than or equal to 10 degrees. ### Claim 16 (depends on 1) The edge-lit back light unit according to claim 1, wherein at least some faces of the inverted pyramid microstructures are aligned to be parallel to the parallel prism microstructures of the diffuser film to within less than or equal to 20 degrees. ### Claim 17 (depends on 1) The edge-lit back light unit according to claim 1, wherein at least some faces of the inverted pyramid microstructures are oriented about 45° relative to the parallel prism microstructures of the diffuser film. ### Claim 18 (depends on 1) The edge-lit back light unit according to claim 1, further comprising a plurality of LEDs positioned along the width of the light guide film. ### Claim 19 (depends on 18) The edge-lit back light unit according to claim 18, wherein the diffuser film comprises angle-bending microstructures oriented to bend light in a direction aligned with the plurality of prism microstructures and away from the plurality of LEDs. ### Claim 20 An edge-lit back light unit for a backlit display, the edge-lit back light unit comprising: a) a diffusive reflector; b) an edge-lit light guide film positioned above the diffusive 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 diffusive reflector is configured to couple light that is input at a light input edge of the edge-lit light guide film out of the edge-lit light guide film with an angular distribution that is directed away from the light input edge and runs nominally along the length of the edge-lit light guide film; c) 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 and being formed of a material having a refractive index, and a plurality of inverted pyramid microstructures on an opposite side thereof, the inverted pyramid microstructures having an apex angle and being formed of a material having a refractive index; and d) 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. ### Claim 21 (depends on 20) The edge-lit back light unit according to claim 20, wherein the plurality of parallel prism microstructures of the diffuser film is substantially aligned with the plurality of parallel micro prisms of at least one of the pair of crossed brightness enhancement films. ### Claim 22 (depends on 20) The edge-lit back light unit according to claim 20, wherein the plurality of parallel micro prisms of the at least one of the pair of crossed brightness enhancement films is oriented to be most closely aligned with a light direction. ### Claim 23 (depends on 20) The edge-lit back light unit according to claim 20, wherein the at least one of the pair of crossed brightness enhancement films is positioned at a top of the edge-lit back light unit. ### Claim 24 (depends on 20) The edge-lit back light unit according to claim 20, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle of about 110°. ### Claim 25 (depends on 20) The edge-lit back light unit according to claim 20, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle of about 90°. ### Claim 26 (depends on 20) The edge-lit back light unit according to claim 20, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle of about 80°. ### Claim 27 (depends on 20) The edge-lit back light unit according to claim 20, wherein the apex angle of at least one of the inverted pyramid microstructures comprises an angle between about 78° and 92°. ### Claim 28 (depends on 20) The edge-lit back light unit according to claim 20, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index of at least one of 1.5, 1.57, 1.61, 1.62, 1.63, 1.64, 1.65, or 1.7. ### Claim 29 (depends on 20) The edge-lit back light unit according to claim 20, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.49 and 1.58. ### Claim 30 (depends on 20) The edge-lit back light unit according to claim 20, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.60 to 1.65. ### Claim 31 (depends on 20) The edge-lit back light unit according to claim 20, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.55 to 1.7. ### Claim 32 (depends on 20) The edge-lit back light unit according to claim 20, wherein the refractive index of the material of at least one of the inverted pyramid microstructures comprises a refractive index between 1.5 to 1.65. ### Claim 33 A diffuser film for a back light unit comprising: a) a substrate; b) a plurality of parallel prism microstructures positioned on a bottom surface of the substrate, at least some of the plurality of parallel prism microstructures having an apex angle between 78° and 92° and a refractive index between 1.49 and 1.58, the plurality of parallel prism microstructures configured to receive light having a peak optical distribution between 15° and 20° and a full width half maximum angle of diffusion of between 25° to 45°; and c) a plurality of inverted pyramid microstructures positioned on a top surface of the substrate, at least some of plurality of the inverted pyramid microstructures having an apex angle between 80° and 110° and a refractive index between 1.49 and 1.7, the diffuser film providing light from the top surface having a peak optical distribution between 30° to 50° and a full width half maximum angle of diffusion of 55° to 85°.