CROSS-REFERENCE TO RELATED PPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63/423604 filed on November 8, 2022, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

Field

[0002] The present disclosure relates generally to backlights for displays. More particularly, it relates to backlights including a patterned diffuser.

Technical Background

[0003] Liquid crystal displays (LCDs) are commonly used in various electronics, such as cell phones, laptops, electronic tablets, televisions, and computer monitors. LCDs are light valve-based displays in which the display panel includes an array of individually addressable light valves. LCDs may include a backlight for producing light that may then be wavelength converted, filtered, and/or polarized to produce an image from the LCD. Backlights may be edge-lit or direct-lit. Edge-lit backlights may include a light emitting diode (LED) array edge- coupled to a light guide plate that emits light from its surface. Direct-lit backlights may include a two-dimensional (2D) array of LEDs directly behind the LCD panel.

[0004] Direct-lit backlights may have the advantage of improved dynamic contrast as compared to edge-lit backlights. For example, a display with a direct-lit backlight may independently adjust the brightness of each LED to set the dynamic range of the brightness across the image. This is commonly known as local dimming. To achieve desired light uniformity and/or to avoid hot spots in direct-lit backlights, however, a diffuser plate or film may be positioned at a distance from the LEDs, thus making the overall display thickness greater than that of an edge-lit backlight. Lenses positioned over the LEDs have been used to improve the lateral spread of light in direct-lit backlights. The optical distance (OD) between the LEDs and the diffuser plate or film in such configurations (e.g., from at least 10 to typically about 20-30 millimeters), however, still results in an undesirably high overall display thickness and/or these configurations may produce undesirable optical losses as the backlight thickness is decreased. While edge-lit backlights may be thinner, the light from each LED may spread across a large region of the light guide plate such that turning off individual LEDs or groups of LEDs may have only a minimal impact on the dynamic contrast ratio.

SUMMARY

[0005] Some embodiments of the present disclosure relate to a backlight. The backlight includes a substrate, a plurality of light sources, a reflective layer, a plurality of elements, and a patterned diffuser. The plurality of light sources are proximate the substrate. The reflective layer is on the substrate and includes a first reflectance. The plurality of elements are proximate the substrate and each element includes a second reflectance different from the first reflectance. The patterned diffuser includes a plurality of patterned reflectors and a plurality of compensation features over the plurality of light sources and the plurality of elements. Each patterned reflector is over a corresponding light source and includes a varying transmittance, and each compensation feature is over a corresponding element.

[0006] Yet other embodiments of the present disclosure relate to a backlight. The backlight includes a substrate, a plurality of light sources, a reflective layer, a plurality of elements, and a patterned diffuser. The plurality of light sources are proximate the substrate. The reflective layer is on the substrate and includes a first reflectance. The plurality of elements are proximate the substrate and each element includes a second reflectance different from the first reflectance. The patterned diffuser includes a plurality of patterned reflectors over the plurality of light sources and the plurality of elements. The plurality of patterned reflectors includes asymmetric reflectors over corresponding light sources arranged adjacent to a corresponding element and symmetric reflectors over corresponding light sources not arranged adjacent to a corresponding element.

[0007] Yet other embodiments of the present disclosure relate to a backlight. The backlight includes a substrate, a plurality of light sources, a reflective layer, and a patterned diffuser. The plurality of light sources are proximate the substrate. The reflective layer is on the substrate. The patterned diffuser includes a plurality of patterned reflectors over the plurality of light sources. Each patterned reflector is aligned with a corresponding light source. Each patterned reflector includes a reflectance varying from a first value at a first location at a center of each patterned reflector to a second value less than the first value at a second location at a first distance from the first location, and varying from the second value at the second location to a third value greater than the second value at a third location at a second distance from the first location greater than the first distance.

[0008] Yet other embodiments of the present disclosure relate to a backlight. The backlight includes a substrate, a plurality of light sources, a reflective layer, and a plurality of elements. The plurality of light sources are proximate the substrate. The reflective layer is on the substrate and includes a first reflectance. The plurality of elements are proximate the substrate and each element is proximate a corresponding first, second, third, and fourth nearest light source of the plurality of light sources. A corresponding center of each of the corresponding first, second, third, and fourth light sources forms a corresponding quadrilateral as vertices. Each element includes a second reflectance different from the first reflectance. A distance between a center of each element and the corresponding first nearest light source is at least about 80 percent of a distance between a center of the corresponding quadrilateral and the corresponding first nearest light source.

[0009] Yet other embodiments of the present disclosure relate to a backlight. The backlight includes a substrate, a plurality of dimming zones, a reflective layer, and an element proximate the substrate within each dimming zone. Each dimming zone includes a plurality of light sources proximate the substrate and includes a first pitch Px and a second pitch Py between the plurality of light sources. The reflective layer is on the substrate and includes a first reflectance. The element includes a second reflectance different from the first reflectance and a distance dl between a center of the element and a nearest light source of the plurality of light sources is given by: 0.5 x ^Px x Px + Py x Py > dl > MAX(0.5 x Px, 0.5 x Py).

[0010] The backlights disclosed herein are thin direct-lit backlights with improved light efficiency and uniformity. The backlights have an improved ability to hide light sources and mitigate local luminance disparity due to absorptive elements and/or due to the intersection between two or more light source zones resulting in a thinner backlight. The improved ability to hide the light sources and mitigate local luminance disparity allows for the removal of so- called “hot” spots directly above the light sources of the backlight and so-called “dark” spots directly above the absorptive elements and/or at the intersections between two or more light source zones, thus resulting in a uniform brightness across the display.

[0011] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings. [0012] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description explain principles and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIGS. 1A-1F are various views of exemplary backlights including a patterned diffuser;

[0014] FIG. 2 is a simplified cross-sectional view of an exemplary liquid crystal display (LCD) including the exemplary backlight of FIG. 1 A;

[0015] FIGS. 3A-3E are various views of other exemplary backlights including a patterned diffuser;

[0016] FIGS. 4A-4D are various views of yet other exemplary backlights including a patterned diffuser;

[0017] FIG. 5 is a chart illustrating exemplary thickness/area coverage versus radial position for a patterned reflector of a patterned diffuser;

[0018] FIGS. 6A and 6B are a simplified cross-sectional view and a top view, respectively, of another exemplary backlight; and

[0019] FIGS. 7A-7E are top views of exemplary dimming zones for a backlight.

DETAILED DESCRIPTION

[0020] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0021] Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0022] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom, vertical, horizontal - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0023] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0024] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0025] Referring now to FIGS. 1A-1F, various views of exemplary backlights are depicted. FIG. 1A is a simplified cross-sectional view of an exemplary backlight 100a. Backlight 100a may include a substrate 102, a reflective layer 104, a plurality of light sources 106, a plurality of elements 107, and a patterned diffuser 108a. Patterned diffuser 108a includes a carrier 110 (e.g., a light guide plate), a plurality of patterned reflectors 112 and 112a, and a plurality of compensation features 118a. The plurality of light sources 106 are proximate (e.g., arranged on) the substrate 102 and are in electrical communication with the substrate 102. The plurality of elements 107 are proximate (e.g., arranged on) the substrate 102 and may be in electrical communication with the substrate 102. The plurality of light sources 106 and/or the plurality of elements 107 may be electrically connected to backplane electronics on the backside of the substrate 102 through vias extending through the substrate 102 (not shown).

[0026] The reflective layer 104 is on the substrate 102 and surrounds each light source 106 and each element 107. In certain exemplary embodiments, the substrate 102 may be reflective such that the reflective layer 104 may be excluded. The patterned diffuser 108a is over the plurality of light sources 106 and the plurality of elements 107 and optically coupled to each light source 106. In certain exemplary embodiments, an optical adhesive (not shown) may be used to couple the plurality of light sources 106 to the patterned diffuser 108a. The optical adhesive (e.g., phenyl silicone) may have a refractive index greater than or equal to a refractive index of the carrier 110. The plurality of patterned reflectors 112 and 112a and the compensation features 118a are arranged on the upper surface of the carrier 110. In other embodiments, the patterned reflectors 112 and 112a and the compensation features 118a may be arranged on the lower surface of the carrier 110. Each patterned reflector 112 and 112a is over a corresponding light source 106. Each compensation feature 118a is over a corresponding element 107.

[0027] Each element 107 may be proximate a light source 106 within a dimming zone. A dimming zone is a group of light sources 106 that can be turned on and off simultaneously. A dimming zone may include any suitable number of light sources 106, such as four light sources arranged in two rows and two columns, nine light sources arranged in three rows and three columns, 16 light sources arranged in four rows and four columns, etc. Each element 107 may be an electrical element, such as a control chip for each dimming zone, or another suitable element. Each element 107 may reduce the luminance locally around the area where each element is located, which may result in mura that affects luminance uniformity. Accordingly, the compensation features 118a are formed to mitigate the effects of the elements 107 by including a higher transmittance (lower reflectance) at the locations on the patterned diffuser 108a corresponding to the elements 107.

[0028] The reflective layer 104 includes a first reflectance and each element 107 includes a second reflectance different from the first reflectance. As used herein, the first reflectance of the reflective layer 104 and the second reflectance of each element 107 are values based on the bidirectional reflectance distribution function (BRDF). In certain exemplary embodiments, the second reflectance is less than the first reflectance. In the embodiment of FIG. 1A, each compensation feature 118a includes an opening extending through a patterned reflector 112a, such that the surface of the carrier 110 is exposed at each compensation feature 118a. Each patterned reflector 112a is similar to each patterned reflector 112 except for the compensation feature 118a within each patterned reflector 112a. Each compensation feature 118a within a patterned reflector 112a includes a transmittance different from a transmittance at corresponding locations of each patterned reflector 112 not corresponding to an element 107. Thus, the compensation feature 118a alters the transmittance of the patterned reflector 112a where the compensation feature is arranged compared to the patterned reflectors 112 where there is no compensation feature 118a. In this embodiment, since each compensation feature 118a includes an opening, each compensation feature includes a constant transmittance. In this embodiment, the center of each patterned reflector 112 and 112a is aligned with a corresponding light source 106 (e.g., the center of the corresponding light source) as indicated at 130. In addition, the center of each compensation feature 118a is aligned with a corresponding element 107 (e.g., the center of the corresponding element) as indicated at 132. [0029] Each patterned reflector 112 and 112a includes a varying transmittance and might include a thickness profde along a width or diameter of the patterned reflector including a substantially flat section as indicated at 113 and a curved section as indicated at 114 extending from and surrounding the substantially flat section 113. The substantially flat section 113 may have a rough surface profde (e.g., slight variations in the thickness throughout the substantially flat section). In certain exemplary embodiments, the substantially flat section 113 varies in thickness by no more than plus or minus 20 percent of an average thickness of the substantially flat section. In this embodiment, the average thickness measured in the direction orthogonal to the carrier 110 is defined as the maximum thickness (T _ma x) of the substantially flat section plus the minimum thickness (T _m in) of the substantially flat section divided by two (i.e., (Tmax+Tmin)/2). For example, for an average thickness of the substantially flat section 113 of about 100 micrometers, the maximum thickness of the substantially flat section would be equal to or less than about 120 micrometers and the minimum thickness of the substantially flat section would be equal to or greater than about 80 micrometers. In other embodiments, the substantially flat section 113 varies in thickness by no more than plus or minus 15 percent of an average thickness of the substantially flat section. For example, for an average thickness of the substantially flat section 113 of about 80 micrometers, the maximum thickness of the substantially flat section would be equal to or less than about 92 micrometers and the minimum thickness of the substantially flat section would be equal to or greater than about 68 micrometers.

[0030] In yet other embodiments, the substantially flat section 113 varies in thickness by no more than plus or minus 10 percent of an average thickness of the substantially flat section. For example, for an average thickness of the substantially flat section 113 of about 50 micrometers, the maximum thickness of the substantially flat section would be equal to or less than about 55 micrometers and the minimum thickness of the substantially flat section would be equal to or greater than about 45 micrometers. In yet other embodiments, the substantially flat section 113 varies in thickness by no more than plus or minus 5 percent of an average thickness of the substantially flat section. The curved section 114 may be defined as the absolute ratio of the change in thickness over the change in the distance from the center of the patterned reflector 112. The slope of the curved section 114 may decrease with the distance from the center of the patterned reflector 112. In certain exemplary embodiments, the slope is highest near the substantially flat section 113, rapidly decreases with the distance from the center of the patterned reflector 112, and then slowly decreases with further distance from the center of the patterned reflector.

[0031] The size L0 (i.e., width or diameter) of each substantially flat section 113 as indicated at 120 (in a plane parallel to the substrate 102) may be greater than the size (i.e., width or diameter) of each corresponding light source 106 as indicated at 124 (in a plane parallel to the substrate 102). The size 120 of each substantially flat section 113 may be less than the size 124 of each corresponding light source 106 times a predetermined value. In certain exemplary embodiments, when the size 124 of each light source 106 is greater than or equal to about 0.5 millimeters, the predetermined value may be about two or about three, such that the size of each substantially flat section 113 is less than three times the size of each light source 106. When the size 124 of each light source 106 is less than 0.5 millimeters, the predetermined value may be determined by the alignment capability between the light sources 106 and the patterned reflectors 112 and 112a, such that the size of each substantially flat section 113 of each patterned reflector 112 and 112a is within a range between about 100 micrometers and about 300 micrometers greater than the size of each light source 106. Each substantially flat section 113 is large enough such that each patterned reflector 112 and 112a can be aligned to the corresponding light source 106 and small enough to achieve suitable luminance uniformity and color uniformity.

[0032] The size LI (i.e., width or diameter) of each patterned reflector 112 is indicated at 122 (in a plane parallel to the substrate 102) and the pitch P between adjacent light sources 106 is indicated at 126. While the pitch is illustrated along one direction in FIG. 1A, the pitch may be different in a direction orthogonal to the direction illustrated. The pitch may, for example, be about 90, 45, 30, 10, 5, 2, 1, or 0.5 millimeters, larger than about 90 millimeters, or smaller than about 0.5 millimeters. In certain exemplary embodiments, the ratio Ll/P of the size 122 of each patterned reflector 112 and 112a over the pitch 126 is within a range between about 0.45 and 1.0. The ratio may vary with the pitch 126 of the light sources 106 and the distance between the emission surface of each light source and the corresponding patterned reflector 112 and 112a. For example, for a pitch 126 equal to about 5 millimeters and a distance between the emission surface of each light source and the corresponding patterned reflector equal to about 0.2 millimeters, the ratio may equal about 0.50, 0.60, 0.70, 0.80, 0.90, or 1.0.

[0033] Each patterned reflector 112 and 112a reflects at least a portion of the light emitted from the corresponding light source 106 into the carrier 110. Each patterned reflector 112 and 112a has a specular reflectance and a diffuse reflectance. The specularly -reflected light exits from the bottom surface of the carrier 110. While specularly-reflected light travels laterally primarily due to the reflection between the reflective layer 104 and the carrier 110, or due to the reflection between the reflective layer 104 and the color conversion layer, diffuser sheet, or diffuser plate (shown below in FIG. 2), some loss of light may occur due to imperfect reflection from the reflective layer 104. The diffusively reflected light has an angular distribution between 0 degrees and 90 degrees measured from the normal of the carrier 110. About 50 percent of the diffusively reflected light has an angle exceeding the critical angle (OTIR) of the total internal reflection. Thus, the diffusively reflected light can travel laterally due to the total internal reflection without any loss, until the light is subsequently extracted out of the carrier 110 by patterned reflectors 112 and 112a.

[0034] FIG. IB is a simplified cross-sectional view of an exemplary backlight 100b. Backlight 100b is similar to backlight 100a previously described and illustrated with reference to FIG. 1A, except that in backlight 100b a patterned diffuser 108b is used in place of patterned diffuser 108a. Patterned diffuser 108b includes a carrier 110 (e.g., a light guide plate), a plurality of patterned reflectors 112 and 112b, and a plurality of compensation features 118b. The plurality of patterned reflectors 112 and 112b and the compensation features 118b are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of patterned reflectors 112 and 112b and the compensation features 118b may be arranged on the lower surface of the carrier 110. Each patterned reflector 112 and 112b is over a corresponding light source 106. Each compensation feature 118b is over a corresponding element 107.

[0035] In this embodiment, each compensation feature 118b includes a transmittance varying from a lower value closer to a center of a patterned reflector 112b to a higher value farther from the center of the patterned reflector 112b. Each patterned reflector 112b is similar to each patterned reflector 112 except for the compensation feature 118b within each patterned reflector 112b. Each compensation feature 118b within a patterned reflector 112b includes a transmittance different from a transmittance at corresponding locations of each patterned reflector 112 not corresponding to an element 107. Thus, the compensation feature 118b alters the transmittance of the patterned reflector 112b where the compensation feature is arranged compared to the patterned reflectors 112 where there is no compensation feature 118b. In this embodiment, the center of each patterned reflector 112 and 112b is aligned with a corresponding light source 106 (e.g., the center of the corresponding light source) as indicated at 130. In addition, the center of each compensation feature 118b is aligned with a corresponding element 107 (e.g., the center of the corresponding element) as indicated at 132. [0036] FIG. 1C is a simplified cross-sectional view of an exemplary backlight 100c. Backlight 100c is similar to backlight 100a previously described and illustrated with reference to FIG. 1A, except that in backlight 100c a patterned diffuser 108c is used in place of patterned diffuser 108a. Patterned diffuser 108c includes a carrier 110 (e.g., a light guide plate), a plurality of patterned reflectors 112 and 112c, and a plurality of compensation features 118c. The plurality of patterned reflectors 112 and 112c and the compensation features 118c are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of patterned reflectors 112 and 112c and the compensation features 118c may be arranged on the lower surface of the carrier 110. Each patterned reflector 112 and 112c is over a corresponding light source 106. Each compensation feature 118c is over a corresponding element 107.

[0037] In this embodiment, each compensation feature 118c includes a layer including a constant thickness. Each patterned reflector 112c is similar to each patterned reflector 112 except for the compensation feature 118c within each patterned reflector 112c. Each compensation feature 118c within a patterned reflector 112c includes a transmittance different from a transmittance at corresponding locations of each patterned reflector 112 not corresponding to an element 107. In some embodiments, each compensation feature 118c within a patterned reflector 112c includes a higher transmittance than a transmittance at corresponding locations of each patterned reflector 112 not corresponding to an element 107. In other embodiments, each compensation feature 118c within a patterned reflector 112c includes a lower transmittance than a transmittance at corresponding locations of each patterned reflector 112 not corresponding to an element 107. Thus, the compensation feature 118c alters the transmittance of the patterned reflector 112c where the compensation feature is arranged compared to the patterned reflectors 112 where there is no compensation feature 118c. In this embodiment, since each compensation feature 118c includes a constant thickness, each compensation feature includes a constant transmittance. In this embodiment, the center of each patterned reflector 112 and 112c is aligned with a corresponding light source 106 (e.g., the center of the corresponding light source) as indicated at 130. In addition, the center of each compensation feature 118c is aligned with a corresponding element 107 (e.g., the center of the corresponding element) as indicated at 132. [0038] FIG. ID is a simplified cross-sectional view of an exemplary backlight lOOd. Backlight lOOd is similar to backlight 100a previously described and illustrated with reference to FIG. 1A, except that in backlight lOOd, the center of each patterned reflector 112 and 112a is offset with respect to a corresponding light source 106 (e.g., the center of the corresponding light source) as indicated at 134 and the center of each compensation feature 118a is offset with respect to a corresponding element 107 (e.g., the center of the corresponding element) as indicated at 136. While patterned diffuser 108a including patterned reflectors 112 and 112a and compensation features 118a are shown in FIG. ID to illustrate the offsets 134 and 136, the offsets 134 and 136 may also be applied to patterned diffuser 108b of FIG. IB or 108c of FIG. 1C.

[0039] Due to asymmetry caused by the compensation features 118a, the misalignment tolerance of the patterned diffuser 108a toward the direction of the compensation features 118a may be degraded. Mura visibility becomes asymmetric and increases in the direction of the elements 107. With the asymmetric misalignment tolerance, to improve the misalignment sensitivity in the direction of the elements 107, the center of each patterned reflector 112 and 112a may be shifted from the center of the corresponding light source 106 in the opposite direction to the corresponding element 107. The intentional misalignment between the patterned reflectors 112 and 112a may be within a range between about 100 micrometers and about 200 micrometers. This intentional misalignment, however, may reduce the misalignment sensitivity in an orthogonal direction.

[0040] FIG. IE is a top view of the plurality of light sources 106, the reflective layer 104, and the plurality of elements 107 on the substrate 102 for a backlight 100, such as backlight 100a, 100b, or 100c previously described and illustrated with reference to FIGS. 1A-1C, respectively. Light sources 106 are arranged in a 2D array including a plurality of rows and a plurality of columns. While 36 light sources 106 are illustrated in FIG. IE in six rows and six columns, in other embodiments backlight 100 may include any suitable number of light sources 106 arranged in any suitable number of rows and any suitable number of columns. Light sources 106 may also be arranged in other periodic patterns, for example, a hexagonal or triangular lattice, or as quasi-periodic or non-strictly periodic patterns. For example, the spacing between light sources 106 may be smaller at the edges and/or comers of the backlight 100.

[0041] In certain exemplary embodiments as illustrated in FIG. IE, each light source 106 may be rectangular in shape such that a length of each light source 106 is different from a width of each light source 106. In other embodiments, each light source 106 may have another suitable shape, such as a square shape or a circular shape. In this embodiment, each dimming zone indicated at 140 includes four light sources 106 in a two by two arrangement for each element 107. Light sources 106 within a row have a first pitch (e.g., center to center) as indicated at 142, and light sources 106 within a column have a second pitch (e.g., center to center) as indicated at 144. The distance between an element 107 and the adjacent light source 106 (e.g., center to center) within each dimming zone 140 is indicated at 146. In certain exemplary embodiments, the first pitch 142 may be different from the second pitch 144. In other embodiments, the first pitch 142 may equal the second pitch 144. In the embodiment illustrated in FIG. IE, the first pitch 142 is less than the second pitch 144.

[0042] The smaller the distance 146, the more light that is absorbed by each element 107 due to more light near the corresponding light source 106. Due to the absorption, there is lower luminance around the location of the element 107. Thus, to mitigate the effect of lower luminance caused by the elements 107, the compensation features (e.g., 118a, 118b, and/or 118c) disclosed herein are formed on the patterned diffuser (e.g., 108a, 108b, and/or 108c).

[0043] Referring back to FIGS. 1A-1D, substrate 102 may be a printed circuit board (PCB), a glass or plastic substrate, or another suitable substrate for passing electrical signals to each light source 106 and each element 107 for individually controlling each light source and each element. Substrate 102 may be a rigid substrate or a flexible substrate. For example, substrate 102 may include flat glass or curved glass. The curved glass, for example, may have a radius of curvature less than about 2000 millimeters, such as about 1500, 1000, 500, 200, or 100 millimeters. The reflective layer 104 may include, for example, metallic foils, such as silver, platinum, gold, copper, and the like; dielectric materials (e.g., polymers such as polytetrafluoroethylene (PTFE)); porous polymer materials, such as polyethylene terephthalate (PET), Poly(methyl methacrylate) (PMMA), polyethylene naphthalate (PEN), polyethersulfone (PES), etc.; multi-layer dielectric interference coatings, or reflective inks, including white inorganic particles such as titania, barium sulfate, etc., or other materials suitable for reflecting light and tuning the color of the reflected and transmitted light, such as colored pigments.

[0044] Each of the plurality of light sources 106 may, for example, be an LED (e.g., size larger than about 0.5 millimeters), a mini -LED (e.g., size between about 0.1 millimeters and about 0.5 millimeters), a micro-LED (e.g., size smaller than about 0.1 millimeter), an organic LED (OLED), or another suitable light source having a wavelength ranging from about 400 nanometers to about 750 nanometers. In other embodiments, each of the plurality of light sources 106 may have a wavelength shorter than 400 nanometers and/or longer than 750 nanometers. The light from each light source 106 is optically coupled to the carrier 110. As used herein, the term “optically coupled” is intended to denote that a light source is positioned at a surface of the carrier 110 and is in optical communication with the carrier 110 directly or through an optically-clear adhesive, so as to introduce light into the carrier that at least partially propagates due to total internal reflection. The light from each light source 106 is optically coupled to the carrier 110 such that a first portion of the light travels laterally in the carrier 110 due to the total internal reflection and is extracted out of the carrier by the patterned reflectors 112 and 112a, 112b, or 112c and compensation features 118a, 118b, or 118c, and a second portion of the light travels laterally between the reflective layer 104 and the patterned reflectors 112 and 112a, 112b, or 112c and compensation features 118a, 118b, or 118c due to multiple reflections at the reflective surfaces of the reflective layer 104 and the patterned reflectors 112 and 112a, 112b, or 112c and compensation features 118a, 118b, or 118c or between an optical film stack (shown in FIG. 2) and the reflective layer 104.

[0045] According to various embodiments, the carrier 110 may include any suitable transparent material used for lighting and display applications. As used herein, the term “transparent” is intended to denote that the carrier has an optical transmission of greater than about 70 percent over a length of 500 millimeters in the visible region of the spectrum (about 420-750 nanometers). In certain embodiments, an exemplary transparent material may have an optical transmittance of greater than about 50 percent in the ultraviolet (UV) region (about 100-400 nanometers) over a length of 500 millimeters. According to various embodiments, the carrier may include an optical transmittance of at least 95 percent over a path length of 50 millimeters for wavelengths ranging from about 450 nanometers to about 650 nanometers.

[0046] The optical properties of the carrier may be affected by the refractive index of the transparent material. According to various embodiments, the carrier 110 may have a refractive index ranging from about 1.3 to about 1.8. In other embodiments, the carrier 110 may have a relatively low level of light attenuation (e.g., due to absorption and/or scattering). The light attenuation (a) of the carrier 110 may, for example, be less than about 5 decibels per meter for wavelengths ranging from about 420-750 nanometers. The carrier 110 may include polymeric materials, such as plastics (e.g., polymethyl methacrylate (PMMA), methylmethacrylate styrene (MS), polydimethylsiloxane (PDMS)), polycarbonate (PC), or other similar materials. The carrier 110 may also include a glass material, such as aluminosilicate, alkalialuminosilicate, borosilicate, alkali-borosilicate, aluminoborosilicate, alkali- aluminoboro silicate, soda lime, or other suitable glasses. Non-limiting examples of commercially available glasses suitable for use as a glass carrier 110 include EAGLE XG®, Lotus™, Willow®, Iris™, and Gorilla® glasses from Coming Incorporated. In examples where substrate 102 includes curved glass, carrier 110 may also include curved glass to form a curved backlight. In other embodiments, the carrier 110 may have a relatively high level of light attenuation. The light attenuation (a) of the carrier 110 may, for example, be greater than about 5 decibels per meter for wavelengths ranging from about 420-750 nanometers.

[0047] FIG. IF is atop view of a plurality of patterned reflectors 112 and 112a and a plurality of compensation features 118a on a carrier 110 of the patterned diffuser 108a previously described and illustrated with reference to FIG. 1A. While patterned diffuser 108a including patterned reflectors 112 and 112a and compensation features 118a are shown in FIG. IF, the features of patterned diffuser 108a described with reference to FIG. IF may also be applied to patterned diffuser 108b of FIG. IB or 108c ofFIG. 1C.

[0048] Each compensation feature 118a, 118b, or 118c may include a circular shape (as shown in FIG. IF) or an elliptical shape. As previously described, each compensation feature 118a, 118b, or 118c has a higher transmittance than the patterned reflector 112a, 112b, or 112c within which each compensation feature 1 18a. 118b, or 118c is arranged. The size (e.g., width or diameter) of each compensation feature 118a, 118b, or 118c should be large enough so that a sufficient amount of light is transmitted to compensate for the corresponding element 107. The size of each compensation feature 118a, 118b, or 118c, however, should not be so large that the compensation feature is recognizable as mura in the backlight. The optimal size of each compensation feature 118a, 118b, or 118c might depend on the emission properties of the light sources 106 and the optical film used to recycle light within the backlight. For example, for a typical light source with a Lambertian emission profile, each compensation feature might have a size less than about 1 millimeter. For a light source 106 having a wide-angle emission profile, however, each compensation feature might have a size up to about 2 millimeters.

[0049] Each patterned reflector 112 and 112a, 112b, or 112c may include a substantially flat section 113 and a curved section 114 as previously described. The substantially flat section 113 may be more reflective than the curved section 114, and the curved section 114 may be more transmissive than the substantially flat section 113. Each curved section 114 may have properties that change in a continuous and smooth way with distance from the substantially flat section 113. While in the embodiment illustrated in FIG. IF, each patterned reflector 112 and 112a is circular in shape, in other embodiments each patterned reflector 112 and 112a, 112b, or 112c may have another suitable shape (e.g., elliptical, rectangular, hexagonal, etc.). With the patterned reflectors 112 and 112a, 112b, or 112c fabricated directly on the upper surface of the carrier 110, the patterned reflectors 112 and 112a, 112b, or 112c increase the ability of hiding the light sources 106. Fabricating patterned reflectors 112 and 112a, 112b, or 112c directly on the upper surface of the carrier 110 also saves space.

[0050] In certain exemplary embodiments, each patterned reflector 112 and 112a, 112b, or 112c is a diffuse reflector, such that each patterned reflector 112 and 112a, 112b, or 112c further enhances the performance of the backlight by scattering some light rays at high enough angles such that they can propagate in the carrier 110 by total internal reflection. Such rays will then not experience multiple bounces between the patterned reflectors 112 and 112a, 112b, or 112c and the reflective layer 104 or between an optical film stack and the reflective layer 104 and therefore avoid loss of optical power, thereby increasing the backlight efficiency. In certain exemplary embodiments, each patterned reflector 112 and 112a, 112b, or 112c is a specular reflector. In other embodiments, some areas of each patterned reflector 112 and 112a, 112b, or 112c have a more diffuse character of reflectivity and some areas have a more specular character of reflectivity.

[0051] Each patterned reflector 112 and 112a, 112b, or 112c may be formed, for example, by printing (e.g., inkjet printing, screen printing, microprinting, etc.) a pattern with white ink, black ink, metallic ink, or other suitable ink. The printing density, ink thickness, and/or spatial coverage may be varied to form the substantially flat section 113 and the curved section 114 of each patterned reflector 112 and 112a, 112b, or 112c and the compensation feature 118b or 118c of each patterned reflector 112b or 112c. In certain exemplary embodiments, the ink coverage for each compensation feature 118a might be zero percent, and the ink coverage for each compensation feature 118b or 118c might be less than 50 percent (i.e., 50 percent of the surface area of the carrier 110 is covered with ink at compensation features 118b or 118c. Each patterned reflector 112 and 112a, 112b, or 112c may also be formed by first depositing a continuous layer of a white or metallic material, for example by physical vapor deposition (PVD) or any number of coating techniques such as for example slot die or spray coating, and then patterning the layer by photolithography or other known methods of area-selective material removal. Each patterned reflector 112 and 112a, 112b, or 112c may also be formed by other known methods of selectively removing material from the carrier itself, for example through laser ablation or chemical etching into the carrier.

[0052] In certain exemplary embodiments, where white light sources 106 are used, the presence of different reflective and absorptive materials in variable density in the patterned reflectors 112 and 112a, 112b, or 112c may be beneficial for minimizing the color shift across each of the dimming zones of the backlight. Multiple bounces of light rays between the patterned reflectors and the reflective layer 104 (FIGS. 1A-1D) may cause more loss of light in the red part of the spectrum than in the blue, or vice versa. In this case, engineering the reflection to be color neutral, for example by using slightly colored reflective/absorptive materials, or materials with the opposite sign of dispersion (in this case, dispersion means spectral dependence of the reflection and/or absorption) may minimize the color shift. When white light sources 106 are used, it is also beneficial that the patterned reflectors 112 and 112a, 112b, or 112c reflect and transmit a similar amount of blue light as green and red light. The patterned reflectors 112 and 112a, 112b, or 112c may contain microsized particles larger than a threshold size. For example, the threshold size may be about 140 nanometers for titanium dioxide, about 560 nanometers for aluminum oxide, or about 750 nanometers for sodium fluoride. In other examples, the threshold size may be 1, 2, 5, 10, or 20 micrometers. In certain exemplary embodiments where blue light sources 106 are used, it is beneficial that the patterned reflectors 112 and 112a, 112b, or 112c reflect more blue light than green and red light and transmit less blue light than green and red light. The patterned reflectors 112 and 112a, 112b, or 112c may contain nano-sized particles smaller than a threshold size. For example, the threshold size may be about 140 nanometers for titanium dioxide, about 560 nanometers for aluminum oxide, or about 750 nanometers for sodium fluoride.

[0053] Patterned diffuser 108a, 108b, or 108c has a spatially varying transmittance or a spatially varying color shift. Since the spatial reflectance and the spatial transmittance of the patterned diffuser 108a, 108b, or 108c are linked together, the patterned diffuser also has a spatially varying reflectance. For example, at the same location of the patterned diffuser 108a, 108b, or 108c a less (or greater) reflectance is linked to a greater (or less) transmittance.

[0054] FIG. 2 is a cross-sectional view of an exemplary liquid crystal display (LCD) 150. LCD 150 includes a backlight 100a including a patterned diffuser 108a as previously described and illustrated with reference to FIG. 1A. While backlight 100a including patterned diffuser 108a is shown in FIG. 2, the features of LCD 150 described with reference to FIG. 2 may also be applied to backlight 100b of FIG. IB or 100c of FIG. 1C. In addition, the backlight of LCD 150 includes optionally a diffuser plate 152 over the backlight 100a, optionally a color conversion layer 154 (e.g., a quantum dot film or a phosphor film) over the diffuser plate 152, optionally a prismatic film 156 over the color conversion layer 154, and optionally a reflective polarizer 158 over the prismatic film 156. LCD 150 also includes a display panel 160 over the reflective polarizer 158 of the backlight. In certain exemplary embodiments, the reflective polarizer 158 may be bonded to the display panel 160.

[0055] To maintain the alignment between the light sources 106 and the patterned reflectors 112 and 112a on the carrier 110 for the proper functioning of the backlight 100a, it is advantageous if the carrier 110 and the substrate 102 are made of the same or similar type of material so that both the patterned reflectors 112 and 112a on the carrier 110 and the light sources 106 on the substrate 102 are registered well to each other over a large range of operating temperatures. In certain exemplary embodiments, the carrier 110 and the substrate 102 are made of the same plastic material. In other embodiments, the carrier 110 and the substrate 102 are made of the same or similar type of glass.

[0056] An alternative solution to keep the carrier 110 and light sources 106 on the substrate 102 in alignment is to use a highly flexible substrate. The highly flexible substrate may be made of a polyimide or other high temperature resistant polymer fdm to allow component soldering. The highly flexible substrate may also be made of materials such as FR4 or fiberglass, but of a significantly less thickness than usual. In certain exemplary embodiments, an FR4 material of 0.4 millimeters thickness may be used for substrate 102, which may be sufficiently flexible to absorb the dimensional changes resulting from changing operating temperatures.

[0057] FIGS. 3A-3E are various views of other exemplary backlights including a patterned diffuser. FIG. 3A is a simplified cross-sectional view and FIG. 3B is a top view of an exemplary backlight 100c. Backlight 100c is similar to backlight 100a previously described and illustrated with reference to FIG. 1A, except that in backlight 100c a patterned diffuser 108e is used in place of patterned diffuser 108a. Patterned diffuser 108e includes a carrier 110 (e.g., a light guide plate) and a plurality of patterned reflectors 112, 112d, and 112e. The plurality of patterned reflectors 112, 112d, and 112e are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of patterned reflectors 112, 112d, and 112e may be arranged on the lower surface of the carrier 110. The plurality of patterned reflectors 112, 112d, and 112e includes asymmetric reflectors 112d and 112e over corresponding light sources 106 arranged adjacent to a corresponding element 107 and symmetric reflectors 112 over corresponding light sources 106 not arranged adjacent to a corresponding element 107. The asymmetric reflectors 112d and 112e may include an elliptical shape, while the symmetric reflectors 112 may include a circular shape or an elliptical shape having a different area than the asymmetric reflectors. In this embodiment, the asymmetric reflectors 112d and 112e are formed to mitigate the absorptive effects of the elements 107.

[0058] In certain exemplary embodiments, a first asymmetric reflector 112d over a corresponding first light source 106 is adjacent to a first side of a corresponding element 107 and includes a first area, and a second asymmetric reflector 112e over a corresponding second light source 106 is adjacent to a second side of the corresponding element 107 and includes a second area different from the first area. The first light source 106 (e.g., the center 170 of the first light source) may be arranged a first distance from the corresponding element 107 (e.g., the center 172 of the corresponding element) as indicated at 174. The second light source 106 (e.g., the center 170 of the second light source) may be arranged a second distance from the corresponding element 107 (e.g., the center 172 of the corresponding element) as indicated at 176. In certain exemplary embodiments, the first light source 106 may be closer to the corresponding element 107 than the second light source 106, such that the distance 174 is less than the distance 176. In this embodiment, the first area of each first patterned reflector 112d is less than the second area of each second patterned reflector 112e. The center of each patterned reflector 112 may be aligned with a corresponding light source 106 (e.g., center 170 of a corresponding light source) or the center of each patterned reflector 112 may be offset with respect to a corresponding light source (e.g., center 170 of a corresponding light source). The asymmetric patterned reflectors 112d and 112e adjacent to a corresponding element 107 improve the luminance uniformity of the backlight 100c by mitigating the effects due to the absorptive elements 107.

[0059] FIG. 3C is a simplified cross-sectional view and FIG. 3D is a top view of an exemplary backlight lOOf. Backlight lOOf is similar to backlight lOOe previously described and illustrated with reference to FIGS. 3A and 3B, except that in backlight lOOf elements 107 are arranged in a different location and a patterned diffuser 108f is used in place of patterned diffuser 108e. Patterned diffuser 108f includes a carrier 110 (e.g., a light guide plate) and a plurality of patterned reflectors 112 and 112f. The plurality of patterned reflectors 112 and 112f are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of patterned reflectors 112 and 112f may be arranged on the lower surface of the carrier 110. The plurality of patterned reflectors 112 and 112f includes asymmetric reflectors 112f over corresponding light sources 106 arranged adjacent to a corresponding element 107 and symmetric reflectors 112 over corresponding light sources 106 not arranged adjacent to a corresponding element 107. The asymmetric reflectors 112f may include an elliptical shape, while the symmetric reflectors 112 may include a circular shape. In this embodiment, the asymmetric reflectors 112f are formed to mitigate the absorptive effects of the elements 107. [0060] In certain exemplary embodiments, a first asymmetric reflector 112f over a corresponding first light source 106 is adjacent to a first side of a corresponding element 107, and a second asymmetric reflector 112f (having an opposite orientation) is over a corresponding second light source 106 adjacent to a second side of the corresponding element 107. The asymmetric reflectors 112f all have the same area. The first light source 106 (e.g., the center 170 of the first light source) may be arranged a first distance from the corresponding element 107 (e.g., the center 172 of the corresponding element) as indicated at 174. The second light source 106 (e.g., the center 170 of the second light source) may be arranged a second distance from the corresponding element 107 (e.g., the center 172 of the corresponding element) as indicated at 176. In this embodiment, the first distance 174 is equal to the second distance 176. The center of each patterned reflector 112 may be aligned with a corresponding light source 106 (e.g., center 170 of a corresponding light source) or the center of each patterned reflector 112 may be offset with respect to a corresponding light source (e.g., center 170 of a corresponding light source). The asymmetric patterned reflectors 112f adjacent to a corresponding element 107 improve the luminance uniformity of the backlight lOOf by mitigating the effects due to the absorptive elements 107.

[0061] FIG. 3E is a top view of an exemplary backlight 100g. Backlight 100g is similar to backlight lOOe previously described and illustrated with reference to FIGS. 3A and 3B, except that in backlight 100g elements 107 are arranged in a different location and a patterned diffuser 108g is used in place of patterned diffuser 108e. Patterned diffuser 108g includes a plurality of patterned reflectors 112 and 112g over the plurality of light sources 106 and the plurality of elements 107. The plurality of patterned reflectors 112 and 112g include asymmetric reflectors 112g over corresponding light sources 106 arranged adjacent to a corresponding element 107 and symmetric reflectors 112 over corresponding light sources 106 not arranged adjacent to a corresponding element 107.

[0062] In this embodiment, four patterned reflectors 112g are adjacent to each element 107 such that the element 107 is an equal distance from each of the four patterned reflectors 112g. Each patterned reflector 112g includes a circular shape minus a missing part facing the element 107 such that a circular portion of the carrier 110 directly over each element 107 is free of patterned reflector material. The asymmetric patterned reflectors 112g adjacent to a corresponding element 107 improve the luminance uniformity of the backlight 100g by mitigating the effects due to the absorptive elements 107.

[0063] FIGS. 4A-4D are various views of yet other exemplary backlights including a patterned diffuser. FIG. 4A is a simplified cross-sectional view and FIG. 4B is a top view of an exemplary backlight 200a. Backlight 200a may include a substrate 102, a reflective layer 104, a plurality of light sources 106, and a patterned diffuser 208a. Patterned diffuser 208a includes a carrier 110 (e .g. , a light guide plate) and a plurality of patterned reflectors 212a. The plurality of light sources 106 are proximate (e.g., arranged on) the substrate 102 and are in electrical communication with the substrate 102. The reflective layer 104 is on the substrate 102 and surrounds each light source 106. In certain exemplary embodiments, the substrate 102 may be reflective such that the reflective layer 104 may be excluded. The patterned diffuser 208a is over the plurality of light sources 106 and optically coupled to each light source 106. In certain exemplary embodiments, an optical adhesive (not shown) may be used to couple the plurality of light sources 106 to the patterned diffuser 208a. The optical adhesive (e.g., phenyl silicone) may have a refractive index greater than or equal to a refractive index of the carrier 110. The plurality of patterned reflectors 212a are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of patterned reflectors 212a may be arranged on the lower surface of the carrier 110. Each patterned reflector 212a is over a corresponding light source 106. In this embodiment, the center of each patterned reflector 212a is aligned with a corresponding light source 106 (e.g., the center of the corresponding light source) as indicated at 230.

[0064] Each patterned reflector 212a includes a varying transmittance and might include a thickness profile along a width or diameter of the patterned reflector including a substantially flat section as indicated at 213, a curved section as indicated at 214 extending from and surrounding the substantially flat section 213, and a comer section 215 at each interface with an adjacent patterned reflector 212a. The substantially flat section 213 may have a rough surface profile (e.g., slight variations in the thickness throughout the substantially flat section). In certain exemplary embodiments, the substantially flat section 213 varies in thickness by no more than plus or minus 20 percent of an average thickness of the substantially flat section. In this embodiment, the average thickness measured in the direction orthogonal to the carrier 110 is defined as the maximum thickness (Tmax) of the substantially flat section plus the minimum thickness (Tmin) of the substantially flat section divided by two (i.e., (T _m ax+T _m in)/2). For example, for an average thickness of the substantially flat section 213 of about 100 micrometers, the maximum thickness of the substantially flat section would be equal to or less than about 120 micrometers and the minimum thickness of the substantially flat section would be equal to or greater than about 80 micrometers. In other embodiments, the substantially flat section 213 varies in thickness by no more than plus or minus 15 percent of an average thickness of the substantially flat section. For example, for an average thickness of the substantially flat section 213 of about 80 micrometers, the maximum thickness of the substantially flat section would be equal to or less than about 92 micrometers and the minimum thickness of the substantially flat section would be equal to or greater than about 68 micrometers. [0065] In yet other embodiments, the substantially flat section 213 varies in thickness by no more than plus or minus 10 percent of an average thickness of the substantially flat section. For example, for an average thickness of the substantially flat section 213 of about 50 micrometers, the maximum thickness of the substantially flat section would be equal to or less than about 55 micrometers and the minimum thickness of the substantially flat section would be equal to or greater than about 45 micrometers. In yet other embodiments, the substantially flat section 213 varies in thickness by no more than plus or minus 5 percent of an average thickness of the substantially flat section. The curved section 214 may be defined as the absolute ratio of the change in thickness over the change in the distance from the center of the patterned reflector 212a. The slope of the curved section 214 may decrease with the distance from the center of the patterned reflector 212a. In certain exemplary embodiments, the slope is highest near the substantially flat section 213, rapidly decreases with the distance from the center of the patterned reflector 212a, and then slowly decreases with further distance from the center of the patterned reflector. The comer section 215 may include a curved section having a slope that increases with the distance from the center of the patterned reflector 212a, and then reaches a substantially flat section at the interface with an adjacent patterned reflector 212a. The substantially flat section of the comer section 215 may have substantially the same thickness or area coverage as the substantially flat section 213, or the substantially flat section of the comer section 215 may have a thickness or area coverage less than the thickness or area coverage of the substantially flat section 213.

[0066] The size L0 (i.e., width or diameter) of each substantially flat section 213 as indicated at 220 (in a plane parallel to the substrate 102) may be greater than the size (i.e., width or diameter) of each corresponding light source 106 as indicated at 124 (in a plane parallel to the substrate 102). The size 220 of each substantially flat section 213 may be less than the size 124 of each corresponding light source 106 times a predetermined value. In certain exemplary embodiments, when the size 124 of each light source 106 is greater than or equal to about 0.5 millimeters, the predetermined value may be about two or about three, such that the size of each substantially flat section 213 is less than three times the size of each light source 106. When the size 124 of each light source 106 is less than 0.5 millimeters, the predetermined value may be determined by the alignment capability between the light sources 106 and the patterned reflectors 212a, such that the size of each substantially flat section 213 of each patterned reflector 212a is within a range between about 100 micrometers and about 300 micrometers greater than the size of each light source 106. Each substantially flat section 213 is large enough such that each patterned reflector 212a can be aligned to the corresponding light source 106 and small enough to achieve suitable luminance uniformity and color uniformity.

[0067] The size LI (i.e., width or diameter) of the substantially flat section in combination with the curved section 214 of each patterned reflector 212a is indicated at 222 (in a plane parallel to the substrate 102). The size L2 (i.e., width or diameter) of each patterned reflector 212a is indicated at 223 (in a plane parallel to the substrate 102). The pitch P between adjacent light sources 106 is indicated at 126. While the pitch is illustrated along one direction in FIG. 4 A, the pitch may be different in a direction orthogonal to the direction illustrated. The pitch may, for example, be about 90, 45, 30, 10, 5, 2, 1, or 0.5 millimeters, larger than about 90 millimeters, or smaller than about 0.5 millimeters. In certain exemplary embodiments, the ratio Ll/P of the size 222 of each patterned reflector 212a over the pitch 126 is within a range between about 0.45 and 0.9. The ratio may vary with the pitch 126 of the light sources 106 and the distance between the emission surface of each light source and the corresponding patterned reflector 212a. For example, for a pitch 126 equal to about 5 millimeters and a distance between the emission surface of each light source and the corresponding patterned reflector equal to about 0.2 millimeters, the ratio may equal about 0.50, 0.60, 0.70, 0.80, or 0.90. The ratio L2/P of the size 223 of each patterned reflector 212a over the pitch 126 is 1.0. [0068] Accordingly, as indicated at 226 in FIG. 4B, each patterned reflector 212a has a reflectance varying from a first value at a first location at a center (e.g., 230) of each patterned reflector 212a to a second value less than the first value at a second location (e.g., 231) at a first distance from the first location, and varying from the second value at the second location to a third value greater than the second value at athird location (e.g., 232) at a second distance from the first location greater than the first distance. In certain exemplary embodiments, the third value equals the first value. The third location of each patterned reflector 212a is proximate an intersection of the patterned reflector 212a with at least two (e.g., three) adjacent patterned reflectors 212a.

[0069] Each patterned reflector 212a reflects at least a portion of the light emitted from the corresponding light source 106 into the carrier 110. Each patterned reflector 212a has a specular reflectance and a diffuse reflectance. The specularly-reflected light exits from the bottom surface of the carrier 110. While specularly-reflected light travels laterally primarily due to the reflection between the reflective layer 104 and the carrier 110, or due to the reflection between the reflective layer 104 and the color conversion layer, diffuser sheet, or diffuser plate (shown above in FIG. 2), some loss of light may occur due to imperfect reflection from the reflective layer 104. The diffusively reflected light has an angular distribution between 0 degrees and 90 degrees measured from the normal of the carrier 110. About 50 percent of the diffusively reflected light has an angle exceeding the critical angle (OTIR) of the total internal reflection. Thus, the diffusively reflected light can travel laterally due to the total internal reflection without any loss, until the light is subsequently extracted out of the carrier 110 by patterned reflectors 212a.

[0070] The comer sections 215 of each patterned reflector 212a might improve the luminance uniformity of the backlight 200a compared to a backlight including patterned reflectors without comer sections 215. Comer sections 215 enhance light extraction locally and increase the brightness of the backlight 200a. At the center of each light source zone, the patterned glass diffuser 208a reflects back most of the light directly from the light source 106 and creates rays that are totally internally reflected. The totally internally reflected rays travel laterally in the carrier 110 and are extracted at the comers of the light source zones. As the distance increases from the light sources 106, however, the totally internally reflected light intensity decreases. To mitigate this effect, light extraction efficiency is improved at the comers of the light source zones by the comer features 215. The distance (LD) from the center of a light source 106 beyond which the comer features 215 are beneficial depends upon multiple factors, including the size 124 of each light source 106, the pitch 126 between light sources 106, and the optical distance (OD) between the light sources 106 and the patterned glass diffuser 208a. For small light sources 106 (e.g., less than about 0.5 millimeters) and a negligible OD (e.g., less than about 1 millimeter), LD might be greater than about 3 millimeters. If OD is not negligible (e.g., greater than about 1 millimeter), LD might equal about 3 + OD/2 in millimeters. If the pitch 126 is less than two times LD, the comer sections 215 may not be needed. In addition, if the OD is large enough, the comer sections 215 may not be needed since a larger OD improves luminance uniformity. In certain exemplary embodiments, comer sections 215 may be beneficial when the light source pitch to OD ratio is at least two. The comers sections 215 may be printed with the same ink as the center patterns of each patterned reflector 212a, or may be printed separately with different ink. The ink of the comers sections 215 may be white ink or clear ink. The area coverage in the comer sections 215 may be about 50 percent or more to enhance light extraction. The comer sections 215 may be formed using any suitable process, such as inkjet printing, screen printing, microprinting, etc.

[0071] FIG. 4C is a top view of an exemplary backlight 200b. Backlight 200b is similar to backlight 200a previously described and illustrated with reference to FIGS. 4A and 4B, except that backlight 200b includes a patterned diffuser 208b in place of patterned diffuser 208a. Paterned diffuser 208b includes a carrier 110 (e.g., a light guide plate) and a plurality of paterned reflectors 212b. The plurality of patterned reflectors 212b are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of paterned reflectors 212b may be arranged on the lower surface of the carrier 110. Each paterned reflector 212b is over a corresponding light source 106. In this embodiment, the center of each paterned reflector 212b is aligned with a corresponding light source 106 (e.g., the center of the corresponding light source).

[0072] In this embodiment, each paterned reflector 212b is similar to each paterned reflector 212a except paterned reflectors 212b include rectangular features 240 in place of comer features 215. Each rectangular feature 240 is proximate (e.g., directly adjacent) an intersection of the paterned reflector 212b with an adjacent paterned reflector 212b. Each paterned reflector 212b may include two rectangular features 240 on opposing sides of each circular center patern of each paterned reflector. As indicated at 242 in FIG. 4C, each paterned reflector 212b has a reflectance varying from a first value at a first location at a center (e.g., 230) of each paterned reflector 212b to a second value less than the first value at a second location (e.g., 243) at a first distance from the first location, and varying from the second value at the second location to a third value greater than the second value at a third location (e.g., 244) at a second distance from the first location greater than the first distance. In certain exemplary embodiments, the third value equals the first value. In other embodiments, the third value is less than the first value. The third location of each paterned reflector 212b is proximate an intersection of the paterned reflector 212b with at least one adjacent paterned reflector 212b. Rectangular features 240 enhance light extraction locally and increase the brightness of the backlight 200b.

[0073] FIG. 4D is a top view of an exemplary backlight 200c. Backlight 200c is similar to backlight 200a previously described and illustrated with reference to FIGS. 4A and 4B, except that backlight 200c includes a paterned diffuser 208c in place of paterned diffuser 208a. Paterned diffuser 208c includes a carrier 110 (e.g., a light guide plate) and a plurality of paterned reflectors 212c. The plurality of patterned reflectors 212c are arranged on the upper surface of the carrier 110. In other embodiments, the plurality of paterned reflectors 212c may be arranged on the lower surface of the carrier 110. Each paterned reflector 212c is over a corresponding light source 106. In this embodiment, the center of each paterned reflector 212c is aligned with a corresponding light source 106 (e.g., the center of the corresponding light source). [0074] In this embodiment, each patterned reflector 212c is similar to each patterned reflector 212a except patterned reflectors 212c also include rectangular features 240 and 250 in addition to comer features 215. Each rectangular feature 240 and 250 is proximate (e.g., directly adjacent) an intersection of the patterned reflector 212c with an adjacent patterned reflector 212c. Each patterned reflector 212c may include two rectangular features 240 on first opposing sides of each circular center pattern of each patterned reflector and two rectangular features 250 on second opposing sides of each circular center pattern of each patterned reflector. In certain exemplary embodiments, rectangular features 240, rectangular features 250, and/or comer features 215 may have the same transmittance. In other embodiments, rectangular features 240, rectangular features 250, and/or comer features 215 may have different transmittance s. As indicated at 242 in FIG. 4D, each patterned reflector 212c has a reflectance varying from a first value at a first location at a center (e.g., 230) of each patterned reflector 212c to a second value less than the first value at a second location (e.g., 243) at a first distance from the first location, and varying from the second value at the second location to a third value greater than the second value at athird location (e.g., 244) at a second distance from the first location greater than the first distance. In certain exemplary embodiments, the third value equals the first value. In other embodiments, the third value is less than the first value. The third location of each patterned reflector 212c is proximate an intersection of the patterned reflector 212c with at least one adjacent patterned reflectors 212c.

[0075] As indicated at 252, the reflectance of each patterned reflector further varies from the first value at the first location (e.g., 230) to the second value at a fourth location (e.g., 253) at the first distance from the first location, and varies from the second value at the fourth location to a fourth value greater than the second value and less than the third value at a fifth location (e.g., 254) at a third distance from the first location greater than the second distance. The third location of each patterned reflector 212c includes a first rectangular feature 240 including a first rectangular area proximate an intersection of the patterned reflector 212c with an adjacent patterned reflector 212c, and the fifth location of each patterned reflector 212c includes a second rectangular feature 250 including a second rectangular area perpendicular to the first rectangular area and proximate an intersection of the patterned reflector 212c with another adjacent patterned reflector 212c. Rectangular features 240 and 250 and comer features 215 enhance light extraction locally and increase the brightness of the backlight 200c.

[0076] FIG. 5 is a chart 300 illustrating exemplary thickness/area coverage versus radial position for a patterned reflector of a patterned diffuser, such as a patterned reflector 212a, 212b, or 212c of FIGS. 4A-4D. In one embodiment as indicated by curve 302, as the distance from the center of the patterned reflector increases, the thickness/area coverage is substantially constant at a maximum value, then the thickness/area coverage decreases to a minimum value, remains substantially constant at the minimum value, increases back to the maximum value, and remains substantially constant at the maximum value. In another embodiment as indicated by curve 304, as the distance from the center of the patterned reflector increases, the thickness/area coverage is substantially constant at a maximum value, then the thickness/area coverage decreases to a minimum value, remains substantially constant at the minimum value, increases back to a value between the minimum and maximum value, and remains substantially constant at the value between the minimum and maximum value.

[0077] For patterned reflectors 212a of FIG. 4B, the radial position of chart 300 may correspond to 226 from the center of a patterned reflector 212a to the comer of the patterned reflector 212a. For patterned reflectors 212b of FIG. 4C, the radial position of chart 300 may correspond to 242 from the center of a patterned reflector 212b to a side of the patterned reflector 212b. For patterned reflectors 212c of FIG. 4D, the radial position of chart 300 may correspond to 242 from the center of a patterned reflector 212c to a first side of the patterned reflector 212c, may correspond to 252 from the center of a patterned reflector 212c to a second side of the patterned reflector 212c perpendicular to the first side, and/or may correspond to 226 from the center of a patterned reflector 212c to the comer of the patterned reflector 212c. [0078] FIGS. 6A and 6B are a simplified cross-sectional view and a top view, respectively, of an exemplary backlight 600. While not illustrated in FIGS. 6A and 6B, backlight 600 may also include a patterned diffuser 108a, 108b, 108c, 108e, 108f, or 108g as previously described with reference to at least FIGS. 1A-1C and 3A-3E. In addition, the backlight 600 may be used in LCD 150 of FIG. 2 in place of backlight 100a. Backlight 600 may include a substrate 102, a reflective layer 104, a plurality of light sources 106, a plurality of elements 607, and a backplane 602. The plurality of light sources 106 are proximate (e.g., arranged on) the substrate 102 and are in electrical communication with the substrate 102. The plurality of elements 607 are proximate (e.g., arranged on and/or through) the substrate 102 and may be in electrical communication with the substrate 102. In certain exemplary embodiments, each element 607 is an electrical contact (e.g., copper, silver) extending through the substrate 102 to electrically couple the plurality of light sources 106 on a first side of the substrate 102 to the backplane 602 on a second side of the substrate 102 opposite to the first side. For example, each element 607 may electrically couple one dimming zone 140 to the backplane 602. The backplane 602 may include circuitry for individually controlling each dimming zone 140 (e.g., on, off, and brightness control). In other embodiments, each element 607 may be a control chip that controls the light sources 106 in the corresponding dimming zone 140.

[0079] The reflective layer 104 is on the substrate 102 and surrounds each light source 106 and each element 607. In certain exemplary embodiments, the substrate 102 may be reflective such that the reflective layer 104 may be excluded. The reflective layer 104 includes a first reflectance and each element 607 includes a second reflectance different from the first reflectance. In certain exemplary embodiments, the second reflectance is less than the first reflectance.

[0080] Referring to the top view of FIG. 6B, the light sources 106 are arranged in a 2D array including a plurality of rows and a plurality of columns. While 36 light sources 106 are illustrated in FIG. 6B in six rows and six columns, in other embodiments backlight 600 may include any suitable number of light sources 106 arranged in any suitable number of rows and any suitable number of columns. Light sources 106 may also be arranged in other periodic patterns, for example, a hexagonal or triangular lattice, or as quasi-periodic or non-strictly periodic patterns. For example, the spacing between light sources 106 may be smaller at the edges and/or comers of the backlight 600.

[0081] In this embodiment, each dimming zone 140 includes four light sources 106 in a two by two arrangement for each element 607. Light sources 106 within a row have a first pitch Px (e.g., center to center) as indicated at 142, and light sources 106 within a column have a second pitch Py (e.g., center to center) as indicated at 144. In certain exemplary embodiments, the first pitch Px 142 may be different from the second pitch Py 144. In other embodiments, the first pitch Px 142 may equal the second pitch Py 144. In the embodiment illustrated in FIG. 6B, the first pitch Px 142 is less than the second pitch Py 144.

[0082] Within each dimming zone 140, the element 607 may be proximate a corresponding first nearest light source 106i, a second nearest light source IO62, a third nearest light source IO63, and a fourth nearest light source IO64. The first, second, third, and fourth nearest light sources may have equal distances to the element 607. In certain exemplary embodiments, a distance dl as indicated at 612 between a center of each element 607 and the corresponding first nearest light source IO61 (e.g., the center of the first nearest light source IO61) is greater than or equal to the first pitch Px 142 or greater than or equal to the second pitch Py 144. A corresponding center of each of the corresponding first nearest light source 1061, second nearest light source IO62, third nearest light source IO63, and fourth nearest light source IO64 forms a corresponding quadrilateral as vertices as indicated at 610. In certain exemplary embodiments, the distance dl 612 between the center of each element 607 and the corresponding first nearest light source 106i (e.g., the center of the first nearest light source 1061) is at least about 80 percent of a distance between a center of the corresponding quadrilateral 610 and the corresponding first nearest light source 106i. In other embodiments, the distance dl 612 between the center of each element 607 and the corresponding first nearest light source 106i (e.g., center of the first nearest light source 106i) is at least about 98 percent of the distance between the center of the corresponding quadrilateral 610 and the corresponding first nearest light source 1061.

[0083] In other embodiments, the distance dl 612 between the center of the element 607 and the nearest light source 106i is given by: dl = 0.5 x ^Px x Px + Py x Py

In other embodiments, the distance dl 612 between the center of the element 607 and the nearest light source 106i is given by:

0.5 0.5 x Py)

In yet other embodiments, the distance dl 612 between the center of the element 607 and the nearest light source 106i is given by:

0.5 x Px x Px + Py x Py > dl > 0.8 x 0.5 x Px x Px + Py x Py

In yet other embodiments, the distance dl 612 between the center of the element 607 and the nearest light source 106i is given by:

0.5 x Px x Px + Py x Py > dl > 0.9 x 0.5 x Px x Px + Py x Py

[0084] A patterned diffuser including a plurality of patterned reflectors and a plurality of compensation features may be over the plurality of light sources 106 and the element 607 within each dimming zone 140. Each patterned reflector may be over a corresponding light source 106 and may include a varying transmittance. Each compensation feature may be over a corresponding element 607. Each element 607 may reduce the luminance locally around the area where each element is located, which may result in mura that affects luminance uniformity. Less light, however, is absorbed by the element 607 the farther the element 607 is arranged from the nearest light source. By arranging each element 607 farther away from the light sources 1061 , IO62, IO63, and IO64 within each dimming zone 140 (e.g., at a maximum possible distance from the nearest light source) the backlight 600 may have a higher luminance and an improved alignment tolerance with the patterned diffuser.

[0085] FIG. 7A is a top view of an exemplary dimming zone 140a for a backlight, such as backlight 600 of FIGS. 6A and 6B. Backlight 600 may include a plurality of dimming zones 140a arranged in rows and columns. Dimming zone 140a includes an element 607 and four light sources 106 including a first nearest light source 106i, a second nearest light source IO62, a third nearest light source IO63, and a fourth nearest light source IO64 arranged in two rows and two columns. Light sources 106 (e.g., IO63 and IO64) within each row have a first pitch Px (e.g., center to center) as indicated at 142a, and light sources 106 (e.g., IO61 and IO63) within each column have a second pitch Py (e.g., center to center) as indicated at 144a. In certain exemplary embodiments, the first pitch Px 142a may be different from the second pitch Py 144a. In other embodiments, the first pitch Px 142a may equal the second pitch Py 144a. In the embodiment illustrated in FIG. 7A, the first pitch Px 142a is less than the second pitch Py 144a.

[0086] A center 706i, 7062, 7063, and 7064 of each of the first nearest light source 1061, second nearest light source IO62, third nearest light source IO63, and fourth nearest light source IO64, respectively, forms a quadrilateral as vertices as indicated at 610a. In this embodiment, the center 707 of the element 607 within the dimming zone 140a is arranged at the center 710a of the quadrilateral 610a, such that the distance 612a between the center 707 of the element 607 and the first nearest light source IO61 (e.g., the center 706i of the first nearest light source IO61) is about 100 percent of the distance between the center 710a of the quadrilateral 610a and the first nearest light source IO61. Thus, the element 607 is arranged at a maximum possible distance from the nearest light source. In this embodiment, the plurality of light sources 1061, IO62, IO63, and IO64 within each dimming zone 140a are aligned with respect to a rectangular grid, such that quadrilateral 610a is a rectangle.

[0087] FIG. 7B is a top view of an exemplary dimming zone 140b for a backlight, such as backlight 600 of FIGS. 6A and 6B. Backlight 600 may include a plurality of dimming zones 140b arranged in rows and columns. Dimming zone 140b includes an element 607 and four light sources 106 including a first light source IO61, a second light source IO62, a third light source IO63, and a fourth light source IO64 arranged in two rows and two columns. Light sources 106 (e.g., IO63 and IO64) within each row have a first pitch Px (e.g., center to center) as indicated at 142b, and light sources 106 (e.g., IO61 and IO63) within each column have a second pitch Py (e.g., center to center) as indicated at 144b. In certain exemplary embodiments, the first pitch Px 142b may be different from the second pitch Py 144b. In other embodiments, the first pitch Px 142b may equal the second pitch Py 144b. In the embodiment illustrated in FIG. 7B, the first pitch Px 142b is less than the second pitch Py 144b. [0088] A center 706i, 7062, 706s, and 7064 of each of the first light source 106i , second light source IO62, third light source IO63, and fourth light source IO64, respectively, forms a quadrilateral as vertices as indicated at 610b. In this embodiment, the center 707 ofthe element 607 within the dimming zone 140b is arranged at a comer of the dimming zone 140b, such that the distance 612b between the center 707 of the element 607 and the first nearest light source IO61 (e.g., the center 706i of the first nearest light source IO61) is the maximum possible distance between the center 707 of the element 607 and the nearest light source, which is light source IO61 in this embodiment. For example, the distance 612b may be greater than the distance between the center 710b of the quadrilateral 610b and the center 7061 of the first light source IO61. In this embodiment, the plurality of light sources IO61, IO62, IO63, and IO64 within each dimming zone 140b are aligned with respect to a rectangular grid, such that quadrilateral 610b is a rectangle.

[0089] FIG. 7C is a top view of an exemplary dimming zone 140c for a backlight, such as backlight 600 of FIGS. 6A and 6B. Backlight 600 may include a plurality of dimming zones 140c arranged in rows and columns. Dimming zone 140c includes an element 607 and four light sources 106 including a first nearest light source IO61, a second nearest light source IO62, a third nearest light source IO63, and a fourth nearest light source IO64 arranged in a two by two array. Light sources 106 (e.g., IO63 and IO64) within each row have a first pitch Px (e.g., center to center) as indicated at 142c, and light sources 106 (e.g., IO61 and IO63) within each column have a second pitch Py (e.g., center to center) as indicated at 144c. In certain exemplary embodiments, the first pitch Px 142c may be different from the second pitch Py 144c. In other embodiments, the first pitch Px 142c may equal the second pitch Py 144c. In the embodiment illustrated in FIG. 7C, the first pitch Px 142c is less than the second pitch Py 144c.

[0090] A center 706i, 7062, 7063, and 7064 of each of the first nearest light source 1061, second nearest light source IO62, third nearest light source IO63, and fourth nearest light source IO64, respectively, forms a quadrilateral as vertices as indicated at 610c. In this embodiment, the center 707 ofthe element 607 within the dimming zone 140c is arranged at the center 710c of the quadrilateral 610c, such that the distance 612c between the center 707 of the element 607 and the first nearest light source IO61 (e.g., the center 706i of the first nearest light source IO61) is about 100 percent of the distance between the center 710c of the quadrilateral 610c and the first nearest light source IO61. Thus, the element 607 is arranged at a maximum possible distance from the nearest light source. In this embodiment, the plurality of light sources 106i, IO62, IO63, and IO64 within each dimming zone 140c are offset with respect to a rectangular grid, such that quadrilateral 610c is not a rectangle.

[0091] FIG. 7D is a top view of an exemplary dimming zone 140d for a backlight, such as backlight 600 of FIGS. 6A and 6B. Backlight 600 may include a plurality of dimming zones 140d arranged in rows and columns. Dimming zone 140d includes an element 607 and six light sources 106 including a first nearest light source IO61, a second nearest light source IO62, a third nearest light source IO63, a fourth nearest light source IO64 a fifth light source IO65, and a sixth light source 106e arranged in two rows and three columns. Light sources 106 (e.g., IO63 and IO64) within each row have a first pitch Px (e.g., center to center) as indicated at 142d, and light sources 106 (e.g., IO61 and IO63) within each column have a second pitch Py (e.g., center to center) as indicated at 144d. In certain exemplary embodiments, the first pitch Px 142d may be different from the second pitch Py 144d. In other embodiments, the first pitch Px 142d may equal the second pitch Py 144d. In the embodiment illustrated in FIG. 7D, the first pitch Px 142d is less than the second pitch Py 144d.

[0092] A center 706i, 7062, 7063, and 7064 of each of the first nearest light source 1061, second nearest light source IO62, third nearest light source IO63, and fourth nearest light source IO64, respectively, nearest to the element 607 forms a quadrilateral as vertices as indicated at 610d. In this embodiment, the center 707 of the element 607 within the dimming zone 140d is arranged at the center 710d of the quadrilateral 610d, such that the distance 612d between the center 707 of the element 607 and the first nearest light source 1061 (e.g., the center 706i of the first nearest light source IO61) is about 100 percent of the distance between the center 710d of the quadrilateral 610d and the first nearest light source 1061. Thus, the element 607 is arranged at a maximum possible distance from the nearest light source . In this embodiment, the plurality of light sources IO61, IO62, IO63, IO64, IO65, and 106e within each dimming zone 140d are aligned with respect to a rectangular grid, such that quadrilateral 610d is a rectangle.

[0093] FIG. 7E is a top view of an exemplary dimming zone 140e for a backlight, such as backlight 600 of FIGS. 6A and 6B. Backlight 600 may include a plurality of dimming zones 140e arranged in rows and columns. Dimming zone 140e includes an element 607 and nine light sources 106 including a first nearest light source IO61, a second nearest light source IO62, a third nearest light source IO63, a fourth nearest light source IO64, a fifth light source IO65, a sixth light source 106e, a seventh light source IO67, an eighth light source I O6x. and a ninth light source IO69 arranged in three rows and three columns. Light sources 106 (e.g., IO63 and IO64) within each row have a first pitch Px (e.g., center to center) as indicated at 142e, and light sources 106 (e.g., 106i and IO63) within each column have a second pitch Py (e.g., center to center) as indicated at 144e. In certain exemplary embodiments, the first pitch Px 142e may be different from the second pitch Py 144e. In other embodiments, the first pitch Px 142e may equal the second pitch Py 144e. In the embodiment illustrated in FIG. 7E, the first pitch Px 142e is less than the second pitch Py 144e.

[0094] A center 706i, 7062, 706g, and 7064 of each of the first nearest light source 1061, second nearest light source IO62, third nearest light source IO63, and fourth nearest light source IO64, respectively, nearest to the element 607 forms a quadrilateral as vertices as indicated at 610e. In this embodiment, the center 707 of the element 607 within the dimming zone 140e is arranged at the center 710e of the quadrilateral 610e, such that the distance 612e between the center 707 of the element 607 and the first nearest light source 1061 (e.g., the center 706i of the first nearest light source IO61) is about 100 percent of the distance between the center 710e of the quadrilateral 610e and the first nearest light source 1061. Thus, the element 607 is arranged at a maximum possible distance from the nearest light source . In this embodiment, the plurality of light sources IO61, IO62, IO63, IO64, IO65, 106e, IO67, 106s, and IO69 within each dimming zone 140e are aligned with respect to a rectangular grid, such that quadrilateral 610e is a rectangle.

[0095] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.