# US 2019/0317364 A1 · Thin two-dimensional local dimming backlight > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0317364 A1 - Document ID: US20190317364A1 - Status: Published application - Kind: A1 - Application number: 15/953,686 - Filed: 2018-04-16 - Published: 2019-10-17 - Earliest claimed: 2018-04-16 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: David James Montgomery; Takeshi Ishida - Web page: https://patentgrep.com/patent/US20190317364A1 ## CPC - G09G 3/36: using liquid crystals - G02B 6/0031: {Reflecting element, sheet or layer} - G02B 6/005: {provided by one optical element, or plurality thereof, placed on the light output side of the light guide} - G02B 26/005: {based on electrowetting} - G02F 1/133603: {with LEDs} - G02F 1/1343: Electrodes {(reflective electrodes G02F1/133553)} - G02F 1/195: {by using frustrated reflection (digital reflection using controlled total internal reflection G02F1/315)} - G09G 3/32: semiconductive, e.g. using light-emitting diodes [LED] - G09G 3/3426: {the different display panel areas being distributed in two dimensions, e.g. matrix} - H05B 45/10: Controlling the intensity of the light - G02B 6/3538: {based on displacement or deformation of a liquid (controlling the intensity of light by displacement or deformation of a fluid in general G02B26/004; fluid-filled lens of variable focal length G02B3/14)} - G02B 6/357: {Electrostatic force (electrostatic forces controlling reflecting elements in general G02B26/0841)} - G09G 3/348: {based on the deformation of a fluid drop, e.g. electrowetting} - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - 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 - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract A backlight assembly includes a light source, a light guide optically coupled to the light source that receives light from the light source, a substrate including an electrode layer and a hydrophobic surface located on the electrode layer, wherein the hydrophobic surface of the substrate is spaced apart from a surface of the light guide to define a cell gap, and a plurality of conductive liquid beads located within the cell gap. Liquid beads that are subject to an actuation voltage applied to the electrode layer are in an actuated state, and liquid beads that are not subject to an actuation voltage applied to the electrode layer are in a non-actuated state. When the liquid beads are in the non-actuated state, the liquid beads are in contact with the surface of the light guide for extracting light from the light guide, and when the liquid beads are in the actuated state, the liquid beads deform such that contact of the liquid beads with the surface of the light guide is reduced relative to the non-actuated state to reduce extraction of light from the lightguide, thereby dimming the backlight assembly. ## Claims ### Claim 1 A backlight assembly comprising: a light source; a light guide optically coupled to the light source that receives light from the light source; a substrate including an electrode layer and a hydrophobic surface located on the electrode layer, wherein the hydrophobic surface of the substrate is spaced apart from a surface of the light guide to define a cell gap; and a plurality of conductive liquid beads located within the cell gap; wherein liquid beads that are subject to an actuation voltage applied to the electrode layer are in an actuated state, and liquid beads that are not subject to an actuation voltage applied to the electrode layer are in a non-actuated state; and wherein when the liquid beads are in the non-actuated state, the liquid beads are in contact with the surface of the light guide for extracting light from the light guide, and when the liquid beads are in the actuated state, the liquid beads deform such that contact of the liquid beads with the surface of the light guide is reduced relative to the non-actuated state to reduce extraction of light from the lightguide, thereby dimming the backlight assembly. ### Claim 2 (depends on 1) The backlight assembly of claim 1, wherein the substrate includes from a viewing side: the hydrophobic surface, a dielectric layer, and the electrode layer. ### Claim 3 (depends on 2) The backlight assembly of claim 2, wherein the electrode layer is patterned to include a plurality of electrode arrangements. ### Claim 4 (depends on 3) The backlight assembly of claim 3, wherein the plurality of electrode arrangements comprises, as to each liquid bead, a ground electrode and at least one additional electrode for receiving a voltage, and the actuation voltage comprises a voltage difference across the electrode arrangement. ### Claim 5 (depends on 4) The backlight assembly of claim 4, wherein the plurality of electrode arrangements comprises, as to each liquid bead, a center ground electrode and two peripheral electrodes. ### Claim 6 (depends on 1) The backlight assembly of claim 1, wherein: the surface of the lightguide that defines the cell gap has a lenticular prism surface; a peak of each prism of the lenticular prism surface is aligned with a respective liquid bead such that each liquid bead is in contact with a respective prism with the peak of the respective prism being immersed within the liquid bead when the liquid bead is in a non-actuated state; and when a liquid bead is actuated the actuated liquid bead moves down the respective prism to reduce the light extraction by reduced contact of the actuated liquid bead with the respective prism. ### Claim 7 (depends on 1) The backlight assembly of claim 1, wherein when the liquid beads are in the actuated state, the liquid beads are not in contact with the surface of the lightguide that defines the cell gap. ### Claim 8 (depends on 1) The backlight assembly of claim 1 wherein the plurality of liquid beads is grouped in zones, and liquid beads within a given zone are commonly controlled to be in the actuated state or non-actuated state. ### Claim 9 (depends on 1) The backlight assembly of claim 1, wherein the substrate further comprises support structures for supporting the liquid beads on the hydrophobic surface. ### Claim 10 (depends on 9) The backlight assembly of claim 9, wherein the support structures comprise, for each liquid bead, a hydrophilic central pillar with the liquid bead surrounding the central pillar. ### Claim 11 (depends on 9) The backlight assembly of claim 9, wherein the support structures comprise, for each liquid bead, a hydrophobic edge pillar that is placed along an edge of the liquid bead. ### Claim 12 (depends on 11) The backlight assembly of claim 11, wherein the edge pillar is a triangular pillar. ### Claim 13 (depends on 1) The backlight assembly of claim 1, wherein a density of the liquid beads increases with distance from the light source. ### Claim 14 (depends on 1) The backlight assembly of claim 1, wherein the liquid beads are water located in air within the cell gap. ### Claim 15 (depends on 1) The backlight assembly of claim 1, wherein the light source comprises a plurality of light emitting diodes that are positioned to emit light to an edge of the light guide. ### Claim 16 (depends on 1) The backlight assembly of claim 1, further comprising one or more optical components for the control of light emission from the backlight assembly. ### Claim 17 (depends on 16) The backlight assembly of claim 16, wherein optical components include a specular reflector on a non-viewing side of the backlight assembly relative to the lightguide, and at least one brightness enhancing film on a viewing side of the backlight assembly relative to the lightguide. ### Claim 18 A method of operating a backlight assembly for active dimming control comprising the steps of: providing a backlight assembly including a light source; a light guide optically coupled to the light source that receives light from the light source; a substrate including an electrode layer and a hydrophobic surface located on the electrode layer, wherein the hydrophobic surface of the substrate is spaced apart from a surface of the light guide to define a cell gap; and an array of conductive liquid beads located within the cell gap; wherein liquid beads that are subject to an actuation voltage applied to the electrode layer are in an actuated state, and liquid beads that are not subject to an actuation voltage applied to the electrode layer are in a non-actuated state; and wherein when the liquid beads are in the non-actuated state, the liquid beads are in contact with the surface of the light guide for extracting light from the light guide, and when the liquid beads are in the actuated state, the liquid beads deform such that contact of the liquid beads with the surface of the light guide is reduced relative to the non-actuated state to reduce extraction of light from the lightguide, thereby dimming the backlight assembly; the method further comprising sequentially operating the backlight assembly to illuminate the array of liquid beads in sequence by: time-sequentially switching on the light source to apply respective data for each sequence; and time-sequentially retaining an extracting zone within the array of liquid beads by maintaining the extracting zone in a non-actuated state for light extraction corresponding to the data, while generating a non-extracting zone that does not extract light by actuating liquid beads in the non-extracting zone; wherein the backlight assembly is sequentially operated in a time of one frame during which the array of liquid beads is illuminated. ### Claim 19 (depends on 18) The method of operating a backlight assembly of claim 18, wherein the extracting zone corresponds in each sequence to a different row or column within the array of liquid beads. ### Claim 20 (depends on 18) The method of operating a backlight assembly of claim 18, wherein sequentially operating the backlight assembly includes placing the backlight assembly in an initial state in which the entire array of liquid beads is non-actuated, and no light emission data is being applied to the light source.