Light control film with asymmetric transmission profile

Abstract

A light control film includes a structured first major surface. The structured first major surface includes structures extending in a thickness direction of the light control film and separated by one or more grooves. Each structure has a first side surface opposite a second side surface, and each groove has a planar landing joining the corresponding structures. The first side surface is substantially orthogonal with a first adjacent landing. The second side surface makes an angle of greater than about 95 degrees with a second adjacent landing. At least 70% of the first and second side surfaces, and at most 30% of the one or more landings, coated with a cover layer. The cover layer coated on the first side surface has a first average thickness T1, and the cover layer coated on the second side surface has a second average thickness T2, such that T1 > T2.

Description

[0001] LIGHT CONTROL FILM WITH ASYMMETRIC TRANSMISSION PROFILE

[0002] Summary

[0003] In some aspects of the present description, a light control film is provided, the light control film having a structured first major surface opposite a second major surface. The structured first major surface includes a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves. Each structure has a first side surface opposite a second side surface. Each groove has one or more substantially planar landings joining the corresponding adjacent structures. The first side surface is substantially orthogonal with a first adjacent landing of the one or more landings, and the second side surface makes an angle greater than about 95 degrees with a second adjacent landing of the one or more landings. At least 70% of the first and second side surfaces and at most 30% of the one or more landings are coated with a cover layer. The cover layer coated on the first side surface has a first average thickness Tl, and the cover layer coated on the second side surface has a second average thickness T2, such that Tl is greater than T2.

[0004] In some aspects of the present description, a method of making a light control film is provided, the method of making a light control film including providing a substantially light transmissive film having a structured first major surface and an opposing second major surface, the structured first major surface including a plurality of structures separated by one or more grooves extending in a thickness direction of the light control film and each structure having a first side surface opposite a second side surface, and each groove having one or more substantially planar landings joining the corresponding adjacent structures, the first side surface substantially orthogonal with a first adjacent landing of the one or more landings, the second side surface making an angle greater than about 95 degrees with a second adjacent landing of the one or more landings; covering the structured first major surface with a cover layer; etching the cover layer using a directional first etching process to remove the cover layer from more than about 70% of the one or more landings but less than about 30% of each of the first and second side surfaces, such that, the cover layer coated on the first side surface has a first average thickness Tl, the cover layer coated on the second side surface having a second average thickness T2, such that Tl is greater than T2.

[0005] In some aspects of the present description, a light control film is provided, the light control film having a structured first major surface opposite a second major surface. The structured first major surface includes a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves. Each structure includes a first side surface opposite a second side surface, and each groove has one or more substantially planar landings joining the corresponding adjacent structures. The first side surface is substantially orthogonal with a first adjacent landing of the one or more landings, and the second side surface makes an angle greater than about 95 degrees with a second adjacent landing of the one or more landings. At least 70% of the first and second side surfaces and at most 30% of the one or more landings are coated with a cover layer. The cover layer on the first and second side surfaces is coated with a light transmissive layer having a plurality of first inorganic particles at a volume loading of greater than about 5%. The light transmissive layer coated on the first side surface has a first average thickness T3, the light transmissive layer coated on the second side surface has a second average thickness T4, such that T3 is greater than T4.

[0006] In some aspects of the present description, a method of making a light control film is provided, the method of making a light control film, the method including providing a substantially light transmissive film having a structured first major surface and an opposing second major surface, the structured first major surface including a plurality of structures separated by one or more grooves extending in a thickness direction of the light control film, each structure having a first side surface opposite a second side surface, and each groove having one or more substantially planar landings joining the corresponding adjacent structures, the first side surface substantially orthogonal with a first adjacent landing of the one or more landings, the second side surface making an angle greater than about 95 degrees with a second adjacent landing of the one or more landings; covering the structured first major surface with a cover layer; covering the cover layer with a light transmissive layer comprising a plurality of first inorganic particles at a volume loading of greater than about 5%; etching the light transmissive layer using a directional first etching process such that the light transmissive layer coated on the first side surface has a first average thickness T3, the light transmissive layer coated on the second side surface has a second average thickness T4, such that T3 is greater than T4, and the light transmissive layer is substantially removed from at least 70% of the landing surfaces; and etching the cover layer using a directional second etching process such that the cover layer is removed from at least 70% of the landing surfaces and removed from less than 30% of the first side surface and second side surface.

[0007] Brief Description of the Drawings

[0008] FIGS. 1A-1C provide side views of a light control film with an asymmetric transmission profile, in accordance with an embodiment of the present description;

[0009] FIG. 2 provides a top view of a light control film with an asymmetric transmission profile, in accordance with an embodiment of the present description;

[0010] FIGS. 3A-3B illustrate examples of a display system having a light control film with an asymmetric transmission profile, in accordance with an embodiment of the present description;

[0011] FIG. 4 is a plot of a light transmission profile of a light control film with an asymmetric transmission profile, in accordance with an embodiment of the present description;

[0012] FIGS. 5A-5B illustrate examples of a light control film featuring louvers / side surfaces with a multilayer construction, in accordance with an embodiment of the present description;

[0013] FIGS. 6A-6C illustrate examples of a light control film featuring louvers / side surfaces with a cover layer and a light transmissive layer, in accordance with an embodiment of the present description; FIGS. 7A-7B illustrate a method of making a light control film, in accordance with an embodiment of the present description;

[0014] FIG. 8 illustrates an alternate method of making a light control film, in accordance with an embodiment of the present description; and

[0015] FIGS. 9A-9B are illustrations supporting the Examples section.

[0016] Detailed Description

[0017] In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense.

[0018] There are various applications in displays and optical system for which having an off-axis, broad, top-hat transmission profile is beneficial. Traditionally, this type of transmission profile has been created using conventional louvers, where the louvers are created by backfilling trapezoid-shaped grooves with black resin, leading to bulky asymmetric louvers with low efficiency (e.g., less than about 35%). This low efficiency can be attributed primarily to the width of the louvers, which block a significant portion of the light from being transmitted through the louver film.

[0019] According to some aspects of the present description, an improved light control film provides a significant increase in transmission efficiency (e.g., about 60%, compared to around 35% with current methods). In some embodiments, a new method is provided which is based on layer-by-layer (LbL) coating and selective removal process (e.g., removal through directional etching).

[0020] According to some aspects of the present description, a light control film includes a structured first major surface opposite a second major surface. In some embodiments, the structured first major surface may include a plurality of structures (e.g., linear ridges) extending in a thickness direction of the light control film separated by one or more grooves. In some embodiments, each structure includes a first side surface opposite a second side surface. In some embodiments, each groove may have one or more substantially planar landings joining the adjacent side surfaces of corresponding structures (i.e., a first side surface of one structure facing a second side surface of an adjacent structure, separated by a groove including a substantially planar landing).

[0021] In some embodiments, wherein the plurality of structures may include linear structures extending substantially across a width direction (e.g., a y-direction) of the light control film and arranged along an orthogonal length direction (e.g., a x-direction) of the light control film. In some embodiments, each linear structure may be separated from each adjacent linear structure by a groove of the one or more grooves.

[0022] In some embodiments, the first side surface may be substantially orthogonal with a first adjacent landing of the one or more landings, and the second side surface may make an angle of greater than 95 degrees (or greater than 100 degrees, or greater than 105 degrees, or greater than 110 degrees, or greater than 115 degrees, or greater than 120 degrees, or greater than 125 degrees, or greater than 130 degrees) with a second adjacent landing of the one or more landings.

[0023] A structured surface can be prepared by any suitable method. In one embodiment, a structure, e.g., a microstructured film, can be prepared by a method including the steps of (a) preparing a polymerizable composition; (b) depositing the polymerizable composition onto a master negative microstructured molding surface (e.g., tool) in an amount barely sufficient to fill the cavities of the master; (c) filling the cavities by moving a bead of the polymerizable composition between a (e.g., preformed film) base layer and the master, at least one of which is flexible; and (d) curing the composition. The deposition temperature can range from ambient temperature to about 180°F (82°C). The master can be metallic, such as nickel, chrome- or nickel-plated copper or brass, or can be a thermoplastic material that is stable under the polymerization conditions and has a surface energy that allows clean removal of the polymerized material from the master. When the base layer is a preformed film, one or more of the surfaces of the film can optionally be primed or otherwise be treated to promote adhesion to the organic material of the microstructure.

[0024] The polymerizable resin can comprise a combination of a first and second polymerizable component selected from (meth) acrylate monomers, (meth)acrylate oligomers, and mixtures thereof. As used herein, “monomer” or “oligomer” is any substance that can be converted into a polymer. The term “(meth) acrylate” refers to both acrylate and methacrylate compounds. In some cases, the polymerizable composition can comprise a (meth)acrylated urethane oligomer, (meth)acrylated epoxy oligomer, (meth)acrylated polyester oligomer, a (meth)acrylated phenolic oligomer, a (meth)acrylated acrylic oligomer, and mixtures thereof.

[0025] The polymerizable resin can be a radiation curable polymeric resin, such as a UV curable resin. In some cases, polymerizable resin compositions useful for the microstructured film of the present disclosure can include polymerizable resin compositions such as are described in U.S. Patent No. 8,012,567 (Gaides et al.).

[0026] The chemical composition and thickness of the base layer (substrate layer) can depend on the end use of the microstructured film. In typical embodiments, the thickness of the base layer can be at least about 0.025 millimeters (mm) and can be from about 0.05 mm to about 0.25 mm. Useful base layer materials include, for example, styrene-acrylonitrile, cellulose acetate butyrate, cellulose acetate propionate, cellulose triacetate, polyether sulfone, polymethyl methacrylate, polyurethane, polyester, polycarbonate, polyvinyl chloride, polystyrene, polyethylene naphthalate, copolymers or blends based on naphthalene dicarboxylic acids, polyolefin-based material such as cast or orientated films of polyethylene, polypropylene, and polycyclo-olefins, polyimides, and glass. Optionally, the base layer can contain mixtures or combinations of these materials. In some embodiments, the base layer may be multi-layered or may contain a dispersed component suspended or dispersed in a continuous phase. Examples of base layer materials include polyethylene terephthalate (PET) and polycarbonate (PC). Examples of useful PET films include photograde polyethylene terephthalate, available from DuPont Films (Wilmington, DE), under the trade designation “Melinex 618”. Examples of optical grade polycarbonate films include LEXAN polycarbonate film 8010, available from GE Polymershapes, Seattle, WA, and Panlite 1151, available from Teijin Kasei, Alpharetta, GA.

[0027] Alternatively, the microstructured film can be prepared by melt extrusion, i.e., casting a fluid resin composition onto a master negative microstructured molding surface (e.g., tool) and allowing the composition to harden. In this embodiment, the protrusions are interconnected in a continuous layer to the base layer. The individual protrusions and connections therebetween generally comprise the same thermoplastic material. The thickness of the land layer (i.e., the thickness excluding that portion resulting from the replicated microstructure) is typically between 0.001 and 0.100 inches and preferably between 0.003 and 0.010 inches. Suitable resin compositions for melt extrusion are transparent materials that are dimensionally stable, durable, weatherable, and readily formable into the desired configuration. Examples of suitable materials include acrylics, which have an index of refraction of about 1.5, such as Plexiglas brand resin manufactured by Rohm and Haas Company (Philadelphia, PA); polycarbonates, which have an index of refraction of about 1.59; reactive materials such as thermoset acrylates and epoxy acrylates; polyethylene based ionomers, such as those marketed under the brand name of SURLYN by Dow Chemical (Midland, MI); (poly)ethylene-co-acrylic acid; polyesters; polyurethanes; and cellulose acetate butyrates. Polycarbonates are particularly suitable because of their toughness and relatively higher refractive index.

[0028] In yet another embodiment, the master negative microstructured molding surface (e.g., tool) can be employed as an embossing tool, such as described in U.S. Pat. No. 4,601,861 (Pricone).

[0029] In some embodiments, a height of the structures (e.g., the height of the structure extending above the substrate layer) may be in the range of about 10 to about 300 microns. Because of the angles defined by the first and second side surfaces, each groove may have a different width at a top of the groove than at the bottom of the groove (near the landing). In some embodiments, for example, the narrower, bottom end of the groove (e.g., the width of the landing) may have a width in the range of about 2 microns to about 75 microns, and the wider, top end of the groove (away from the landing) may have a width in the range of about 6 microns to about 200 microns. In some embodiments, a pitch of the structures (e.g., a distance from the first side surface of one structure to the first side surface of the immediately adjacent structure) may be in the range of about 10 microns to about 500 microns. The ranges listed here are examples only and are not intended to be limiting. The example film depicted in FIG. 9A, and described in the Examples section herein, shows the corresponding measurements of one embodiment of a structured film according to the present description. All measurements in FIG. 9A are in microns, unless otherwise specified.

[0030] In some embodiments, at least 70% (or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%) of the first and second side surfaces, and at most 30% (or at most 25%, or at most 20%, or at most 15%, or at most 10%, or at most 5%) of the one or more landings may be coated with a cover layer (e.g., a light absorbing layer). In some embodiments, the cover layer coated on the first side surface may have a first average thickness Tl, and the cover layer coated on the second side surface may have a second average thickness T2, wherein Tl is greater than T2.

[0031] In some embodiments, Tl may be greater than T2 by at least a factor of 1.1, or at least 1.25, or at least 1.3, or at least 2.0, or at least 2.5, or at least 3.0, or at least 3.5, or at least 4.0, or at least 4.5, or at least 5.0, or at least 5.5, or at least 6.0.

[0032] In some embodiments, the light control film may further include a planarizing overcoat covering, and substantially planarizing, the structured first major surface. In some embodiments, the planarizing overcoat may include an optically clear adhesive. In some embodiments, the planarizing overcoat may include a polymerizable resin (e.g., it may be the same polymerizable resin used to make the structured surface, described elsewhere herein).

[0033] In some embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of a material comprising the first major surface by greater than about 0.07. In some embodiments, the refractive index of the planarizing overcoat may be substantially equal to a refractive index of the material of the first major surface (e.g., the same material may be used for both the planarizing overcoat and the structured first major surface).

[0034] In some embodiments, the cover layer may be light absorbing. In some such embodiments, the light absorbing cover layer may include a poly electrolyte. In some such embodiments, the light absorbing cover layer may include a plurality of light absorbing particles. For example, in some embodiments, the light absorbing particles may include one or more of a dye, a pigment, and a carbon black. In some embodiments, the light absorbing cover layer has an optical density of greater than about 0.1.

[0035] In some embodiments, the cover layer may have an average thickness of greater than about 0.05 microns, or greater than about 0.1 microns, or greater than about 0.15 microns, or greater than about 0.2 microns, or greater than about 0.25 microns, or greater than about 0.3 microns, or greater than about 0.35 microns, or greater than about 0.4 microns, or greater than about 0.45 microns, or greater than about 0.5 microns, or greater than about 0.55 microns, or greater than about 0.6 microns, or greater than about 0.65 microns, or greater than about 0.7 microns, or greater than about 0.75 microns, or greater than about 1.0 microns, or greater than about 1.25 microns, or greater than about 1.5 microns, or greater than about 2 microns, or greater than about 2.5 microns, or greater than about 3 microns. In some embodiments, the cover layer may have an average thickness of less than about 2000 nm, or less than about 1500 nm, or less than about 1000 nm, or less than about 500 nm, or less than about 400 nm, or less than about 300 nm, or less than about 200 nm, or less than about 100 nm, or less than about 50 nm.

[0036] In some embodiments, the cover layer may be light absorbing. The cover layer may absorb light at one more wavelengths in the ultraviolet light range (i.e., 100-400 nm) and / or the visible light range (i.e., 400-700 nm) and / or the infrared light range (i.e., 700 nm - 1 mm). In some such embodiments, the light absorbing cover layer may include a plurality of light absorbing particles. In some such embodiments, the light absorbing particles may include one or more of a dye, a pigment, and a carbon black. In some embodiments, the light absorbing cover layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about

[0037] 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6. In some embodiments, the optical density is less than about 3.0, or less than about

[0038] 2.5, or less than about 2.0. In some embodiments the optical density is between 0.5 and 2.5, or between 1.0 and 2.0 or between 1.2 and 1.8. As used herein, optical density shall be defined as -loglO(T), where T is the optical transmission of the film, and T is defined as VL, where Iois the intensity of incident light and Itis the intensity of the transmitted light (light passing through the medium). For example, if transmission, T, is 1%, the optical density is calculated as -loglO(O.Ol) which is equal to an optical density of 2.0.

[0039] In some embodiments, a display system may include any of the light control films described herein. In some such embodiments, the display may be configured to form an image to a viewer, and the light control film may be disposed between the viewer and the display. In some embodiments, the display system may include a display configured to form an image to a viewer, an extended light source (e.g., a backlight), and any of the light control film embodiments described herein. In some such embodiments, the light control film may be disposed between the extended light source and the display. In some embodiments, the display may be any type of appropriate display device, including but not limited to an LCD or on OLED display.

[0040] In some embodiments, the cover layer may include a core layer sandwiched between a first cladding layer and a second cladding layer. In some such embodiments, the core layer may have a first concentration, Cl, of a light absorbing material, and the first and second cladding layers may have a second concentration, C2, of the light absorbing material, wherein C2 is less than Cl. In some embodiments, the core layer may include 30 wt. % to 100 wt. % of light absorbing material and the first and second cladding layers may each include 0.5 wt. % to 50 wt. % of light absorbing material. In some embodiments, the core layer may include 15 vol. % to 90 vol. % of light absorbing material and the first and second cladding layers may each include 0.3 vol. % to 35 vol. % of light absorbing material.

[0041] In some embodiments, the core layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6. In some such embodiments, thicknesses of the first cladding layer and the core layer on the first side surface are substantially the same as corresponding thicknesses of the of the first cladding layer and the core layer on the second side surface, wherein a thickness of the second cladding layer on the first side surface is greater than a thickness of the second cladding layer on the second side surface.

[0042] In some embodiments, the light control film may have an asymmetric transmission profile. For example, in some embodiments, a transmission profile of the light control film may have a peak transmission at a viewing angle having a magnitude greater than or equal to about 10 degrees, and an average transmission percentage across the entire profile equal to 50% or less of the peak transmission. Stated another way, the transmission profile may have a peak transmission percentage at least 10 degrees from normal, and lower average transmission levels on either side of the location of the peak transmission. For example, when the peak transmission is located at a viewing (polar) angle of greater than zero degrees, transmission percentage at an angle of 50 degrees may be less than 10%, less than 5%, or less than 2%, transmission percentage at an angle of 60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of 70 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of 80 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -20 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -30 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -40 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -50 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -70 degrees may be less than 10%, less than 5% or less than 2%, and transmission percentage at an angle of -80 degrees may be less than 10%, less than 5% or less than 2%. When the peak transmission is located at a viewing (polar) angle of less than zero degrees, transmission percentage at an angle of -50 degrees may be less than 10%, less than 5%, or less than 2%, transmission percentage at an angle of -60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -70 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -80 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +20 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +30 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +40 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +50 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +70 degrees may be less than 10%, less than 5% or less than 2%, and transmission percentage at an angle of +80 degrees may be less than 10%, less than 5% or less than 2%. In some embodiments, the transmission profile exhibits a “top-hat shape”; for example, peak transmission percentage is nearly constant (e.g., within ± 2%T) within a range of viewing (polar angles) for example within 10 degrees, within 20 degrees, or within 30 degrees, or within 40 degrees, or within 50 degrees.

[0043] In some embodiments, the transmission profile of the light control film may have a peak transmission at a viewing angle having a magnitude between about 10 degrees and about 30 degrees. In some such embodiments, an average transmission percentage across the profile may be equal to 50% or less of the peak transmission (i.e., the peak transmission percentage). The transmission percentages listed in the previous paragraph and description of a “top-hat” transmission profile apply to this embodiment as well.

[0044] According to some aspects of the present description, a method of making a light control film includes providing a substantially light transmissive film having a structured first major surface and an opposing second major surface. In some embodiments, the structured first major surface may include a plurality of structures (e.g., linear structures extending across a width of the film and arranged along a length of the film) separated by one or more grooves. In some embodiments, the structures may extend in a thickness direction of the light control film (i.e., they have a height that extends above the plane of the film and its first major surface). In some embodiments, each structure may include a first side surface opposite a second side surface, separated by a substantially planar landing of one of the grooves of the one or more grooves (i.e, each groove may have one or more substantially planar landings joining the side surfaces of corresponding, adjacent structures facing each other across the groove). In some embodiments, the first side surface may be substantially orthogonal with a first adjacent landing of the one or more landings, and the second side surface may make an angle greater than 95 degrees (or greater than 100 degrees, or greater than 105 degrees, or greater than 110 degrees, or greater than 115 degrees, or greater than 120 degrees, or greater than 125 degrees, or greater than 130 degrees) with a second adjacent landing of the one or more landings.

[0045] In some embodiments, the method further includes covering the structured first major surface with a cover layer (e.g., a light-absorbing cover layer). The method may further include etching the cover layer using a directional first etching process (e.g., reactive ion etching) to remove the cover layer from more than about 70%, or more than about 80%, or more than about 90%, or more than about 95% of the one or more landings, but from less than about 30%, or less than about 25%, or less than about 20%, or less than about 15%, or less than about 10%, or less than about 5%) of each of the first and second side surfaces, such that, the cover layer coated on the first side surface has a first average thickness Tl, the cover layer coated on the second side surface having a second average thickness T2, and Tl is greater than T2. In some embodiments, Tl may be greater than T2 by at least a factor of 1.1, or at least a factor of 1.3, or at least a factor of 1.5, or at least a factor of 2.0, or at least a factor of 2.5, or at least a factor of 3.0, or at least a factor of 3.5, or at least a factor of 4.0, or at least a factor of 4.5, or at least a factor of 5.0, or at least a factor of 5.5, or at least a factor of 6.0.

[0046] In some embodiments, the method of making a light control film may further include covering and substantially planarizing the structured first major surface with a planarizing overcoat. In some embodiments, the planarizing overcoat covering may include an optically clear adhesive. In some embodiments, the planarizing overcoat may include a polymerizable resin (e.g., it may be the same polymerizable resin used to make the structured surface, described elsewhere herein).

[0047] In some embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of a material comprising the first major surface by greater than about 0.07. In other embodiments, a refractive index of the planarizing overcoat may be substantially the same as a refractive index of a material comprising the first major surface.

[0048] In some embodiments, the cover layer applied in the method may be light absorbing. In some such embodiments, the light absorbing cover layer may include a poly electrolyte. In some embodiments, the light absorbing cover layer may include a plurality of light absorbing particles, including, but not limited to, a dye, a pigment, and a carbon black, or combinations thereof.

[0049] In some embodiments, the light absorbing cover layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6.

[0050] In some embodiments, the cover layer may include a core layer sandwiched between a first cladding layer and a second cladding layer. In some such embodiments, the core layer may have a first concentration, Cl, of a light absorbing material and the first and second cladding layers may have a second concentration, C2, of the light absorbing material, wherein C2<C 1. In some embodiments, the core layer may include 30 wt. % to 100 wt. % of light absorbing material and the first and second cladding layers may each include 0.5 wt. % to 50 wt. % of light absorbing material. In some embodiments, the core layer may include 15 vol. % to 90 vol. % of light absorbing material and the first and second cladding layers may each include 0.3 vol. % to 35 vol. % of light absorbing material.

[0051] In some embodiments, the core layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm, of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6.

[0052] According to some aspects of the present description, a light control film includes a structured first major surface opposite a second major surface. The structured first major surface may include a plurality of structures extending in a thickness direction of the light control film and separated by one or more grooves. In some embodiments, each structure may include a first side surface opposite a second side surface. In some embodiments, the plurality of structures may include linear structures extending substantially across a width direction (e.g., a y-direction) of the light control film and arranged along an orthogonal length direction (e.g., an x-direction) of the light control film. In some embodiments, each linear structure may be separated from each adjacent linear structure by a groove of the one or more grooves.

[0053] In some embodiments, each groove may have one or more substantially planar landings joining (i.e., connecting) the side surfaces of corresponding, adjacent structures. In some embodiments, the first side surface may be substantially orthogonal with a first adjacent landing of the one or more landings (i.e., substantially vertical in the thickness direction of the light control film). In some embodiments, the second side surface may make an angle greater than about 95 degrees, or about 100 degrees, or about 105 degrees, or about 110 degrees, or about 115 degrees, or about 120 degrees, or about 125 degrees, or about 130 degrees with a second adjacent landing of the one or more landings.

[0054] In some embodiments, at least 70% (or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%) of the first and second side surfaces, and at most 30% (or at most 25%, or at most 20%, or at most 15%, or at most 10%, or at most 5%) of the one or more landings may be coated with a cover layer (e.g., a light-absorbing cover layer). In some such embodiments, the cover layer on the first and second side surfaces may be coated with a light transmissive layer including a plurality of first inorganic particles at a volume loading of greater than about 5%. In some embodiments, the light transmissive layer coated on the first side surface may have a first average thickness T3, and the light transmissive layer coated on the second side surface may have a second average thickness T4, such that T3 is greater than T4. In some embodiments, T3 may be greater than T4 by at least a factor of 1.1, or at least a factor of 1.3, or at least a factor of 1.5, or at least a factor of 1.7, or at least a factor of 1.9, or at least a factor of 2.0, or at least a factor of 2.5, or at least a factor of 3.0, or at least a factor of 3.5, or at least a factor of 4.0.

[0055] In some embodiments, the light control film may further include a planarizing overcoat covering, and substantially planarizing, the structured first major surface. In some such embodiments, the planarizing overcoat may include an optically clear adhesive. In other such embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of a material comprising the first major surface by greater than about 0.07. In still some other such embodiments, a refractive index of the planarizing overcoat may be substantially the same as a refractive index of a material comprising the first major surface (e.g., the same material may be used for both the planarizing overcoat and the structured first major surface).

[0056] In some embodiments, the cover layer may be light absorbing. For example, in some embodiments, the light absorbing cover layer may include a polyelectrolyte. In some embodiments, the light absorbing cover layer may include a plurality of light absorbing particles. In some such embodiments, the light absorbing particles include one or more of a dye, a pigment, and a carbon black. In some embodiments, the light absorbing cover layer may have an optical density of greater than about

[0057] 0.1.

[0058] In some embodiments, any of the light control films described herein may be used in a display system. For example, in some embodiments, a display system may include the light control film and a display configured to form an image to a viewer. In such embodiments, the light control film may be disposed between the viewer and the display. In other embodiments, the display system may include the display configured to form an image to a viewer, an extended light source (e.g., a backlight), and the light control film. In these embodiments, the light control film may be disposed between the extended light source and the display. In some embodiments, the display may be any appropriate display device, including but not limited to an LCD or OLED display.

[0059] In some embodiments, the first inorganic particles of the light transmissive layer may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets. In the embodiments including clay platelets, the clay platelets may include silicates. In some such embodiments, the silicates may include one or more of aluminum silicates and magnesium silicates.

[0060] In some embodiments, the first inorganic particles of the first light transmissive layer may be dispersed in a polymeric binder at the weight loading of the first inorganic particles of greater than about 15%. In some such embodiments, one of the polymeric binder and the plurality of first inorganic particles may include a plurality of positively charged ionic groups, and the other one of the polymeric binder and the plurality of first inorganic particles may include a plurality of negatively charged ionic groups.

[0061] In some embodiments, the polymeric binder may include one or more of poly(ethylenimine) (PEI), poly( allylamine hydrochloride), polyvinylamine, chitosan, polyaniline, polyamidoamine, poly(vinylbenzyltriamethylamine), polydiallyldimethylammonium chloride (PDAC), poly(dimethylaminoethyl methacrylate), poly(methacryloylamino)propyl-trimethylammonium chloride, poly(vinyl sulfate), poly(vinyl sulfonate), poly( acrylic acid) (PAA), poly(methacrylic acid), poly(styrene sulfonate), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethylcellulose, alginate, sulfonated tetrafluoroethylene based fluoropolymers, poly(vinylphosphoric acid), poly(vinylphosphonic acid), polyurethane, and acrylic.

[0062] In some embodiments, any binder present in the first light transmissive layer may be at a weight loading of not greater than about 20%. In other embodiments, the first light transmissive layer may not include any binder.

[0063] In some embodiments, the cover layer may be multilayer and may include a core layer sandwiched between a first cladding layer and a second cladding layer. In some such embodiments, the core layer may have a first concentration, Cl, of a light absorbing material and the first and second cladding layers may have a second concentration, C2, of the light absorbing material. In some such embodiments, C2 may be less than Cl. In some embodiments, the core layer may include 30 wt. % to 100 wt. % of light absorbing material and the first and second cladding layers may each include 0.5 wt. % to 50 wt. % of light absorbing material. In some embodiments, the core layer may include 15 vol. % to 90 vol. % of light absorbing material and the first and second cladding layers may each include 0.3 vol. % to 35 vol. % of light absorbing material.

[0064] In some embodiments, the core layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6.

[0065] In some embodiments, the light control film may have an asymmetric transmission profile. For example, in some embodiments, a transmission profile of the light control film may have a peak transmission at a viewing angle having a magnitude greater than or equal to about 10 degrees, and an average transmission percentage across the entire profile equal to 50% or less of the peak transmission. Stated another way, the transmission profile may have a peak transmission percentage at least 10 degrees from normal, and lower average transmission levels on either side of the location of the peak transmission. For example, when the peak transmission is located at a viewing (polar) angle of greater than zero degrees, transmission percentage at an angle of 50 degrees may be less than 10%, less than 5%, or less than 2%, transmission percentage at an angle of 60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of 70 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of 80 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -20 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -30 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -40 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -50 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -70 degrees may be less than 10%, less than 5% or less than 2%, and transmission percentage at an angle of -80 degrees may be less than 10%, less than 5% or less than 2%. When the peak transmission is located at a viewing (polar) angle of less than zero degrees, transmission percentage at an angle of -50 degrees may be less than 10%, less than 5%, or less than 2%, transmission percentage at an angle of -60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -70 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of -80 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +20 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +30 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +40 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +50 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +60 degrees may be less than 10%, less than 5% or less than 2%, transmission percentage at an angle of +70 degrees may be less than 10%, less than 5% or less than 2%, and transmission percentage at an angle of +80 degrees may be less than 10%, less than 5% or less than 2%. In some embodiments, the transmission profile exhibits a “top-hat shape”; for example, peak transmission percentage is nearly constant (e.g., within ± 2%T) within a range of viewing (polar angles) for example within 10 degrees, within 20 degrees, or within 30 degrees, or within 40 degrees, or within 50 degrees.

[0066] In some embodiments, the transmission profile of the light control film may have a peak transmission at a viewing angle having a magnitude between about 10 degrees and about 30 degrees. In some such embodiments, an average transmission percentage across the profile may be equal to 50% or less of the peak transmission (i.e., the peak transmission percentage). The transmission percentages listed in the previous paragraph and description of a “top-hat” transmission profile apply to this embodiment as well.

[0067] According to some aspects of the present description, a method of making a light control film may include providing a substantially light transmissive film comprising a structured first major surface and an opposing second major surface; covering the structured first major surface with a cover layer; covering the cover layer with a light transmissive layer including a plurality of first inorganic particles at a volume loading of greater than about 5%; etching the light transmissive layer using a directional first etching process (e.g., reactive ion etching) such that the light transmissive layer coated on the first side surface has a first average thickness T3, the light transmissive layer coated on the second side surface has a second average thickness T4, such that T3 is greater than T4, and the light transmissive layer is substantially removed from at least 70% of the landing surfaces; and etching the cover layer using a directional second etching process such that the cover layer is removed from at least 70% of the landing surfaces and removed from less than 30% of the first side surface and second side surface.

[0068] In some embodiments, T3 may be greater than T4 by at least a factor of 1.1, or at least a factor of 1.3, or at least a factor of 1.5, or at least a factor of 1.7, or at least a factor of 1.9, or at least a factor of 2.0, or at least a factor of 2.5, or at least a factor of 3.0, or at least a factor of 3.5, or at least a factor of 4.0.

[0069] In some such embodiments, the structured first major surface may include a plurality of structures separated by one or more grooves extending in a thickness direction of the light control film (having a height above the film). In some such embodiments, each structure may include a first side surface opposite a second side surface. In some embodiments, each groove of the one or more grooves may have one or more substantially planar landings which join the side surfaces of two corresponding, adjacent structures (i.e., that is, a first side surface of one structure facing the second side surface of a second, adjacent structure, the first side surface and the facing second side surface connected by the landing of a groove).

[0070] In some embodiments, the first side surface may be substantially orthogonal with a first adjacent landing of the one or more landings, and the second side surface may make an angle of greater than about 95 degrees with a second adjacent landing of the one or more landings. In some embodiments, the directional first etching process and the directional second etching process may be the same process. In other embodiments, the directional first etching process and the directional second etching process may be different processes.

[0071] In some embodiments, the method of making a light control film may further include covering and substantially planarizing the structured first major surface with a planarizing overcoat. In some such embodiments, the planarizing overcoat covering comprises an optically clear adhesive. In some embodiments, the planarizing overcoat may include a polymerizable resin (e.g., it may be the same polymerizable resin used to make the structured surface, described elsewhere herein).

[0072] In other such embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of a material comprising the first major surface by greater than about 0.07. In still other such embodiments, a refractive index of the planarizing overcoat may be substantially the same as a refractive index of a material comprising the first major surface (e.g., the two materials may be or include substantially the same material).

[0073] In some embodiments, the cover layer may be light absorbing. In some such embodiments, the light absorbing cover layer may include a poly electrolyte. In some embodiments, the light absorbing cover layer may include a plurality of light absorbing particles. In some such embodiments, the light absorbing particles may include one or more of a dye, a pigment, and a carbon black.

[0074] In some embodiments, the light absorbing cover layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm, of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6.

[0075] In some embodiments, the first inorganic particles of the light transmissive layer may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets. In embodiments including clay platelets, the clay platelets may include silicates. In some such embodiments, the silicates comprise one or more of aluminum silicates and magnesium silicates.

[0076] In some embodiments, the first inorganic particles of the first light transmissive layer may be dispersed in a polymeric binder at the weight loading of the first inorganic particles of greater than about 15%. In some such embodiments, one of the polymeric binder and the plurality of first inorganic particles may include a plurality of positively charged ionic groups, and the other one of the polymeric binder and the plurality of first inorganic particles may include a plurality of negatively charged ionic groups. In some such embodiments, the polymeric binder may include one or more of poly(ethylenimine) (PEI), poly(allylamine hydrochloride), polyvinylamine, chitosan, polyaniline, polyamidoamine, poly(vinylbenzyltriamethylamine), polydiallyldimethylammonium chloride (PDAC), poly(dimethylaminoethyl methacrylate), poly(methacryloylamino)propyl-trimethylammonium chloride, poly(vinyl sulfate), poly(vinyl sulfonate), poly( acrylic acid) (PAA), poly(methacrylic acid), poly(styrene sulfonate), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethylcellulose, alginate, sulfonated tetrafluoroethylene based fluoropolymers, poly(vinylphosphoric acid), poly(vinylphosphonic acid), polyurethane, and acrylic.

[0077] In some embodiments, any binder in the first light transmissive layer may be at a weight loading of not greater than about 20%. In other embodiments, the first light transmissive layer may not include any binder.

[0078] In some embodiments, the cover layer may include a core layer sandwiched between a first cladding layer and a second cladding layer. In some such embodiments, the core layer may have a first concentration, Cl, of a light absorbing material, and the first and second cladding layers may have a second concentration, C2, of the light absorbing material. In some such embodiments, C2 may be less than Cl. In some embodiments, the core layer may include 30 wt. % to 100 wt. % of light absorbing material, and the first and second cladding layers may each include 0.5 wt. % to 50 wt. % of light absorbing material. In some embodiments, the core layer may include 15 vol. % to 90 vol. % of light absorbing material and the first and second cladding layers may each include 0.3 vol. % to 35 vol. % of light absorbing material.

[0079] In some embodiments, the core layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm, of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6.

[0080] Turning now to the figures, FIGS. 1A-1C provide side views of an embodiment of a light control film with an asymmetric transmission profile, according to the present description. FIGS. 1 A, IB, and 1C should be considered together for the following discussion. Light control film 100 a structured first major surface 11 and an opposing second major surface 12. In some embodiments, light control film 100 may include a substrate layer 14 disposed on the second major surface 12 (and may, in some embodiments, be considered a part of the second major surface 12). Stated another way, light control film 100 may include a substantially planar second major surface 12, including, at least in some embodiments, a substrate layer 14, and a structured first major surface 11. Possible substrate materials and dimensions are discussed elsewhere herein.

[0081] In some embodiments, structured first major surface 11 may include a plurality of structures 10 extending in a thickness direction (e.g., the z-direction shown in FIG. 1A). In some embodiments, structures 10 may be separated by grooves 15. Each of structures 10 may include a first side surface 20 and an opposing (on the opposite side of the structure) second side surface 25. In some embodiments, each of the first side surfaces 20 and second side surfaces 25 of the plurality of structures 10 may be substantially covered (at least 70% covered) by a cover layer 30. In some embodiments, cover layer 30 may be a light-absorbing cover layer. Each of the structures 10, may be separated from adjacent structures 10 by one or more grooves 15. In some embodiments, each groove 15 may have a substantially planar landing 16, which connects the first side surface 20 of one structure 10 with a second side surface 25 of an adjacent structure 10. In some embodiments, each structure 10 may also have a substantially planar top surface 18. Planar landings 16, as well as planar top surfaces 18, may be substantially uncovered by cover layer 30 (no more than 30% of the surfaces covered by cover layer 30).

[0082] In some embodiments, light control film may further include a planarizing overcoat 17 covering, and substantially planarizing, structured first major surface 11 (i.e., at least partially filling grooves 15). In some embodiments, the planarizing overcoat 17 may “overfill” the grooves 15, such that the planarizing overcoat extends above structures 10 (see, e.g., FIG.7A, subprocess (D)).

[0083] In some embodiments, a material included in planarizing overcoat 17 may be substantially the same as a material included in structures 10. In other embodiments, the material of planarizing overcoat 17 may be different from the material of structures 10.

[0084] As shown in FIG. IB, first side surface 20 may be substantially orthogonal (see 01) with a first adjacent landing 16. In some embodiments, second side surface 25 may make an angle 02 with a second adjacent landing 16. In some such embodiments, the angle 02 may be greater than at least about 95 degrees (i.e., second side surface 25 is inclined from the normal to the landing 16, and at a non-zero angle to first side surface 20).

[0085] Looking at FIG. 1C, the cover layer 30 covering first side surface 20 of light control film 100 may have a first average thickness Tl, and the cover layer 30 covering second side surface 25 may have a second average thickness T2, wherein Tl is greater than T2. In some embodiments, this difference in thicknesses of the cover layer 30 between first side surface 20 and second side surface 25 may be caused by the directional etching process used to remove cover layer 30 from the substantially planar surfaces, landing 16 and planar top surface 18. As first side surface 20 is oriented to be substantially orthogonal to landing 16 (and planar top surface 18), the etching process used to remove cover layer 30 from surfaces 16 and 18 will have less effect on the cover layer 30 of first side surface 20, while second side surface 25, oriented at an angle to first side surface 20, will see more of the effects of the directional etching process. Therefore, the thickness of cover layer 30 on second side surface 25, T2, may be thinner than the thickness of cover layer 30 on first side surface 25, Tl.

[0086] FIG. 2 provides an alternate, top view of the embodiment of light control film 100 of FIG. 1 A (see top image of FIG.2, compared against the side view shown as the bottom image of FIG. 2). This top view is provided to illustrate that, in some embodiments, structures 10 may extend across a width direction (e.g., the y-direction shown in FIG. 2, top) and may be arranged along a length direction (e.g., the x-direction shown in FIG. 2, top). The description and function elements shown in FIG. 2 are identical to their like-numbered components in FIGS. 1A-1C, and, accordingly, no additional description is supplied. FIGS. 3A-3B illustrate alternate embodiments of a display system 300a, 300b having light control film 100, according to the present description. In FIG. 3A, display system 300a includes a display 70 configured to generate an image 71 for viewing by the eye of a viewer 80, disposed between an extended light source 75 (e.g., a backlight) and light control film 100. In embodiment 300a, light 50 is emitted by extended light source 75 and passes through display 70, creating image rays 73. These image rays 73 are then incident on light control film 100. Those image rays 73 that are incident on the cover layer of a first side surface or a second side surface (see surfaces 20 and 25 in FIG. 1A, and cover layer 30) are substantially absorbed and are not substantially transmitted through light control film 100. Those light rays 73 that are aligned such that they pass between the first and second side surfaces without being incident on the cover layer are transmitted through to the eye of the viewer 80. Because of the arrangement of the first and second side surfaces, image rays 73 are transmitted such that there is a transmission peak at a viewing angle that is off of a physical axis 301 of the display system 300a, as shown by the position of eye 80 of the viewer.

[0087] In other embodiments, such as the embodiment shown in FIG. 3B, light control film 100 may be instead disposed between extended light source 75 and display 70. In this embodiment, light rays 50 are emitted by extended light source 75 but are only transmitted toward the display if light rays 50 are aligned with the first and second side surfaces of light control film 100 (that is, if the light rays 50 pass through without being incident on the light-absorbing cover layer 30 of the first and second side surfaces). For example, light rays 50a are incident on one of the first and second side surfaces are substantially absorbed by the cover layer on these surfaces and is not substantially transmitted through the light control film 100. In this embodiment, the light being sent to display 70 is already asymmetric relative to physical axis 301.

[0088] FIG. 4 is a plot of a light transmission profile for an embodiment of a light control film with an asymmetric transmission profile, such as light control film 100 of FIG. 1A. FIG.4 shows plots of 4 different sample light control films created using the methods described herein. In each case, the transmission profile of the light control film (plotted against the viewing angle, or “polar angle” as shown in FIG. 4) has a peak transmission 60 at a viewing angle having a magnitude greater than or equal to about 10 degrees, and an average transmission percentage across the profile equal to 50% or less of the peak transmission. In the embodiments shown in FIG. 4, for example, the sample light control films show a peak transmission percentage between about (0.55) 55% and (0.60) 60% at a viewing / polar angle of about +17 degrees. Of course, this peak transmission could be at about -17 degrees if the films are rotated 180 degrees. In some embodiments, the peak transmission 60 may be at a viewing angle having a magnitude between about 10 degrees and about 30 degrees. The average transmission percentage across the profile may be equal to 50% or less of the peak transmission (i.e., the transmission percentage drops off on either side of the transmission peak transmission).

[0089] FIGS. 5A-5B illustrate embodiments of a light control film featuring louvers / side surfaces with a multilayer construction, according to the present description. Looking at FIGS. 5 A and 5B together, an alternate embodiment of a light control film is shown. In some embodiments, the cover film 30 of light control film 100a may be a multilayer construction, having a core layer 30coresandwiched between a first, inner cladding layer 30ciadi and a second, outer cladding layer 30ciad2- This type of construction can be used to prevent unwanted reflections from the cover layer on the side surfaces. High aspect ratio louvers (such as the louvers created by the light absorbing cover layer on the first and second side surfaces in the light control film described herein) preferably have a relatively high extinction coefficient in order to efficiently absorb light in a thin layer. This high extinction coefficient can produce a reflective, metal-like interface with the transmissive regions of the light control film (the areas between side surfaces within the light control film). It has been found that adding cladding layers on each side of a high extinction coefficient core, for example, reduces louver reflectivity and thereby reduces high angle light leakage through the light control film. This multilayer construction, with an inner cladding layer, a core layer, and an outer cladding layer, can be formed on the sidewalls by depositing the layers over the (e.g., entire) structured surface and then removing the layers from the planar surfaces (such as the planar landing 16 and planar top surface 18 of FIG. 1A) by selectively (e.g., anisotropically) etching the layer from these layers.

[0090] Because the construction of FIGS. 5A and 5B is created using a layer-by-layer or similar deposition method, the three layers of inner cladding layer 30ciadi, core layer 30core, and outer cladding layer 30ciad2 are initially deposited over the entire structured first major surface 11 (see FIG. 1A), including over the planar landings 16 of the grooves 15 and planar top surfaces 18 of the structure 10. As described elsewhere herein, a first directional etching process (e.g., reactive ion etching) is applied which etches away the cover layers from these substantially planar surfaces. The cover layer (including inner cladding layer 30ciadi, core layer 30COre, and outer cladding layer 30ciad2) on the first side surface 20 are minimally etched because the first side surface 20 is substantially orthogonal relative to the landing 16 and the primary direction of the etching process. However, as second side surface 25 is at an increased angle to landing 16, the directional etching process will etch the second side surface 25 more than the first side surface 20. As shown in FIG. 5B, the difference in thicknesses T1 and T2, while still applying to the overall cover layer 30 on the first 20 and second 25 side surfaces, may be more specifically applied to the difference in thicknesses between the outer cladding layer 30ciad2 on each side surface. That is, the outermost layer of the second side surface 25, whether it is only a unitary, single cover layer or the outermost cladding layer of a cover layer having the multilayer construction in FIGS. 5A and 5B, will be subjected more to the effects of the etching process than the same layers on the first side surface 20. Because outer cladding layer 30ciad2 may be subjected more directly to the directional first etching process used to remove cover layer from the planar surfaces, this layer may be applied with a greater initial thickness than inner cladding layer 30ciadi (as shown in FIGS. 5A and 5B). Also, as the inner cladding layer 30ciadi and core layer 30COre, are not exposed directly to the directional first etching process, the thickness of these layers should be substantially the same on the second side surface 25 as they are on the first side surface 20. FIGS. 6A-6C illustrate embodiments of a light control film featuring louvers / side surfaces with a cover layer and a light transmissive layer, according to the present description. Many of the elements shown in FIGS. 6A-6C share reference numbers with their corresponding elements in the embodiment of FIGS. 1 A-1C and are assumed to have the same function as described for those figures, unless specifically stated otherwise.

[0091] In the embodiment of light control film 100b of FIGS. 6A-6C, the first side surface 20 and second side surface 25 of each structure 10 are coated with a light-absorbing cover layer 30, as with previous embodiments described herein. It should be noted that cover layer 30 may be either a single layer cover layer, such as that shown in FIGS. 1A-1C, or a multilayer construction having a cladding-core-cladding structure as shown in FIGS. 5A-5B. In this discussion, “cover layer 30” should be assumed to apply equally to either architecture.

[0092] On top of cover layer 30, facing the interior of each groove 15, a light transmissive layer 35 is disposed. In some embodiments, this light transmissive layer 35 may include a plurality of first inorganic particles at a volume loading of greater than about 5%, as further detailed elsewhere herein. Light transmissive layer 35 acts as an “etch stop” layer to prevent etching of the underlying cover layer 30 that is on the side surfaces. Because of this, it is the light transmissive layer 35 that is exposed to the directional first etching process, such that, as shown in FIG. 6C, the light transmissive layer 35 on first side surface 20 has an average thickness T3, and the light transmissive layer 35 on the second side surface 25 has an average thickness T4, such that T3 is greater than T4 (i.e., the light transmissive layer 35 on second side surface 25 has been at least partially etched by the directional first etching process).

[0093] FIGS. 7A-7B illustrate one method of making a light control film, according to the present description. Looking first at FIG. 7 A, the method of making a light control film (such as light control film 100 of FIG. 1A) includes subprocesses (A), (B), (C), and (D). In subprocess (A), a substantially light transmissive film 110 is provided. In some embodiments, light transmissive film 110 may include a structured first major surface and an opposing second major surface. The structured first major surface may include a plurality of structures 10 separated by grooves 15. Each groove 15 may have a substantially planer landing 16 joining the sides of adjacent structures, and, in some embodiments, each structure 10 may have a substantially planar top surface 18. Each structure has a first side surface 20, which is substantially orthogonal to a first adjacent landing 16, and a second side surface 25, which makes an angle greater than about 95 degrees with a second adjacent landing.

[0094] In subprocess (B), the structured first major surface is coated with a cover layer 30a, which covers the first 20 and second 25 side surfaces of structures 10, as well as planar landings 16 and planar top surfaces 18.

[0095] In subprocess (C), the cover layer 30a is etched using a directional first etching process 120 to remove the cover layer 30a from more than about 70% of the one or more landings 16 but less than about 30% of each of the first and second side surfaces, creating cover layer 30 that exists primarily on the first 20 and second 25 side surfaces. The remaining cover layer on the first side surface 20 has a first average thickness Tl, and the remaining cover layer 30 coated on the second side surface has a second average thickness T2, such that Tl is greater than T2.

[0096] In some embodiments, subprocess (D) may include covering and substantially planarizing the structured first major surface with a planarizing overcoat 17.

[0097] FIG. 7B provides an alternate embodiment (B2) of subprocess (B) from FIG. 7A. In this embodiment, cover layer 30 is deposited as a three-layer structure including an inner cladding layer 30ciadi, a core layer 30cOre, and an outer cladding layer 30ciad2, as described elsewhere herein. As shown in the close-up of the first side surface shown in FIG. 7B, the outermost cladding layer 30ciad2 may be applied thicker than innermost cladding layer 30ciadi, as the outermost cladding layer will be subjected to the directional etching process more directly.

[0098] Other than alternated subprocess (B2), the method outlined in FIG. 7A remains essentially the same.

[0099] FIG. 8 illustrates an alternate method of making a light control film, according to the present description. Looking at FIG. 8, this alternate method of making a light control film (such as light control film 100b of FIG. 6A) includes subprocesses (A), (B), (C), (D), (E), and (F).

[0100] In subprocess (A), a substantially light transmissive film 110 is provided. In some embodiments, light transmissive film 110 may include a structured first major surface and an opposing second major surface. The structured first major surface may include a plurality of structures 10 separated by grooves 15. Each groove 15 may have a substantially planer landing 16 joining the sides of adjacent structures, and, in some embodiments, each structure 10 may have a substantially planar top surface 18. Each structure has a first side surface 20, which is substantially orthogonal to a first adjacent landing 16, and a second side surface 25, which makes an angle greater than about 95 degrees with a second adjacent landing.

[0101] In subprocess (B), the structured first major surface is coated with a cover layer 30a, which covers the first 20 and second 25 side surfaces of structures 10, as well as planar landings 16 and planar top surfaces 18.

[0102] In subprocess (C), cover layer 30a is covered with a light transmissive layer 35a which includes a plurality of first inorganic particles at a volume loading of greater than about 5%.

[0103] In subprocess (D), the light transmissive layer 35a is etched using a directional first etching process 120 to remove the light transmissive layer 35a from more than about 70% of the one or more landings 16 and planar top surfaces 18 but from less than about 30% of each of the first and second side surfaces. The remaining light transmissive layer 35 on the first side surface 20 has a first average thickness T3, and the remaining light transmissive layer 35 coated on the second side surface has a second average thickness T4, such that T3 is greater than T4.

[0104] In subprocess (E), the cover layer 30a is etched using a directional second etching process 125 such that the cover layer is removed from at least 70% of the landing surfaces 16 and planar top surfaces 18, but removed from less than 30% of the first side surface and second side surfaces, creating final cover layer 30 and light transmissive layer 35.

[0105] In some embodiments, subprocess (F) may include covering and substantially planarizing the structured first major surface with a planarizing overcoat 17.

[0106] Examples

[0107] Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Materials Used in the Examples

[0108] Method to Make Microstructured Film (Step 1)

[0109] A diamond was used to cut a cylindrical copper tool having the structure shown in Figure 9A with linear grooves running along the curved portion of the tool and arranged laterally across the width direction of the tool (units of microns for the length dimensions; darker-colored regions represent the metal tool, while lighter-colored regions represent the microreplicated film).

[0110] Resin A was prepared by mixing the materials in Table 1 below. Table 1: Composition of Resin A Used to Make Microstructured Film

[0111] A “cast-and-cure” microreplication process was carried out with Resin A and the tool described above on a continuous microreplication line. The line conditions were resin temperature 130 °F (54.4 °C), coater IR 120 °F (48.9 °C), tool temperature 100 °F (37.8 °C), and line speed 35 feet per minute (fpm) (0.18 meters per second (m / s). Resin A was coated onto 5 mil (127 microns) thick, primed PET film. After coating, the coated film passed under IR heaters. The coated film then passed between a rubber nip roll and metal tool at a nip pressure of 10 psi (69 kPa). The resulting film was cured using two sequential banks of Fusion D lamps both at 100% power. The protrusions of the microstructured film are a negative replication of the grooves of the tool. The channels of the microstructured film are a negative replication of the uncut portions of the tool between the grooves.

[0112] Method to Coat a Light Absorbing Cover Laver (Step 2)

[0113] A black, light-absorbing cover layer was coated conformally on the microstructured film via layer-by-layer (LbL) deposition on a coater as described in US Pat. No. 10,926,289 (Kawakami et al.). First, three separate coating solutions were prepared: Cation, Cover Layer Core Anion, and Cover Layer Clad Anion. The Cation solution was 2.5% solids SC72 with 200 mM NaCl and 0.1% PL92 in DI water. The Cover Layer Core Anion solution was 2.5% solids EXPCB with 50 mM NaCl and 0.1% PL92 in DI water. The Cover Layer Clad Anion solution was 4.0% solids CARBOSET CR-3090, 0.5% solids EXPCB, 50 mM NaCl, and 0.1% PL92. The coating construction was a cladded core as described in U.S. Pat. Appl. No. 2021 / 0333624 (Schmidt et al.). Unless otherwise specified, six bilayers of Cation / Clad Anion were deposited, followed by four bilayers of Cation / Core Anion, followed by six bilayers of Cation / Clad Anion for a total of 16 bilayers. For deposition of the coating, the microstructured film was threaded through the coating line. The coating solutions were separately coated onto the microstructured film with a #4 Mayer Rod fed with needles from a liquid delivery manifold at a flow rate of about 200 mL / min at each coating station. Excess coating solution was removed from the web after each deposition step with air-knives gapped at 40 mil to the web with pressure of about 35 psi. Line speed was 50 feet per minute. Method to Coat a Layer-by-Layer Etch Stop (“Light Transmissive Layer”) (Step 3)

[0114] A nano-SiO2-containing etch stop was deposited conformally on the microstructured film via layer-by-layer (LbL) deposition on a coater as described in US Pat. No. 10,926,289 (Kawakami et al.). Two separate coating solutions were prepared: Cation and Etch Stop Anion. The Cation solution was 2.5% solids SC72 with 200 mM NaCl and 0.1% PL92 in de-ionized (DI) water. The Etch Stop Anion solution was 1.0% solids nano-SiO2 (20 nm particle size), 125 mM NaCl, and 0.1% PL92 in DI water, with pH adjusted to about 10 using IM NaOH. The etch stop comprised six bilayers, denoted as (SC72 / SiO2)6. The Cation and Etch Stop Layer Anion solutions were separately coated onto the microstructured film with a #4 Mayer Rod fed with needles from a liquid delivery manifold at a flow rate of about 200 mL / min at each coating station. Excess coating solution was removed from the web after each deposition step with air-knives gapped at 40 mil to the web with pressure of about 35 psi. Line speed was 50 feet per minute. Thickness of the LbL etch stop coating, determined by analyzing an SEM image with ImageJ software, was 173 ± 34 nm. Weight percent of SiO2, determined by the “Method for Determining Weight% of Inorganic Particles in LbL Etch Stop Coatings” from an equivalent etch stop coating deposited with a small-scale spray coater, was 51.0 wt%. Porosity of this etch stop was not directly measured, but generally the SC72 polymer provides relatively non-porous coatings due to its film forming nature. Calculation of approximate vol% of inorganic particles, assuming 0% porosity, using a density of 2.05 g / cm3 for the SiO2 and a density of 1.00 g / cm3 for the SC72 polymer, gives 34 vol% inorganic particles.

[0115] Method to Selectively Remove Portions of the Etch Stop (Light Transmissive

[0116] Reactive ion etching (RIE) was performed in a home-built parallel plate capacitively coupled plasma reactor. The chamber has a central cylindrical powered electrode with a surface area of 18.3 ft2. After placing the coated film on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 0.26 Pa (2 mTorr). Oxygen (02) and perfluorohexane (C6F14) were introduced into the chamber at flow rates of 1000 SCCM and 200 SCCM, respectively. Treatment was carried out by coupling RF power into the reactor at a frequency of 13.56 MHz, an applied power of 7500 watts, and an approximate pressure of 2.53 Pa (19 mTorr). Treatment time was controlled by moving the coated film through the reaction zone at rate of 3 ft / min, corresponding to an approximate exposure time of 100 sec. Following the treatment, the RF power and the gas supply were stopped and the chamber was returned to atmospheric pressure. Additional information regarding materials and processes for applying cylindrical RIE and further details around the reactor used can be found in US8460568 B2.

[0117] Method to Selectively Remove Portions of the Light Absorbing Cover Layer (Step 4B)

[0118] Reactive ion etching was carried out in the same home-built reactor chamber used in the “Method to Selectively Remove Portions of the Layer-by-Layer Etch Stop (Light Transmissive Layer). After placing the coated film on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 0.13 Pa (1 mTorr). 02 gas was flowed into the chamber at a rate of 1000 SCCM. 13.56 MHz RF power was subsequently coupled into the reactor with an applied power of 9000 W and an approximate pressure of 0.93 Pa (7 mTorr). The film was then carried through the reaction zone at a set rate. At the end of this treatment time, the RF power and the gas supply were stopped, and the chamber was returned to atmospheric pressure.

[0119] Method to Backfill (Step 5)

[0120] The grooves of the microstructured film were backfilled, planarizing the film, with Resin A on a microreplication line using a smooth metal tooling roll. The line conditions were resin temperature 150 °F (65.6 °C), coater IR 150 °F (65.6 °C), tool temperature 150 °F (65.6 °C), and line speed 10 feet per minute (fpm) (0.18 meters per second (m / s). Resin A was first coated onto 3 mil (76 microns) thick, primed PET film. After coating, the coated film passed under IR heaters. The coated film was brought into contact with film processed sequentially through Step 1, Step 2, Step 3, Step 4A, and Step 4B (or Step 1, Step 2, and Step 4B) from an auxiliary unwind and then passed between a rubber nip roll and smooth metal tool at a nip pressure of 8 psi (55 kPa). The laminate film was cured using two sequential banks of Fusion D lamps both at 100% power.

[0121] Method for Measuring the Luminance Profile from a Diffuse Light Source

[0122] A sample of film was placed on a Lambertian light source. When the light transmissive regions are tapered, the film is positioned such that the widest portion of the tapered regions are closer to the light source. An Eldim L80 conoscope (Eldim S.A., Heroville-Saint-Clair, France) was used to detect light output in a hemispheric fashion at all polar and azimuthal angles simultaneously. After detection, a cross section of transmission (e.g., brightness) readings were taken in a direction orthogonal to the direction of the louvers (denoted as a 0° orientation angle), unless indicated otherwise. Relative transmission (i.e., brightness of visible light) is defined as the percentage of on-axis luminance, at a certain viewing angle (or polar angle), between a reading with film and a reading without the film.

[0123] The Lambertian light source consisted of diffuse transmission from a light box having the baseline luminance profile depicted in FIG. 6 of WO 2019 / 118685 Al (Schmidt et al.). The light box was a six-sided hollow cube measuring approximately 12.5 cm x 12.5 cm c 11.5 cm (L x W x H) made from diffuse polytetrafluoroethylene (PTFE) plates of approximately 6 millimeters (mm) thickness. One face of the box was chosen as the sample surface. The hollow light box had a diffuse reflectance of approximately 0.83 measured at the sample surface (e.g., approximately 83%, averaged over the 400-700 nm wavelength range). During testing, the box was illuminated from within through an approximately 1 cm circular hole in the bottom of the box (opposite the sample surface, with the light directed toward the sample surface from inside). The illumination was provided using a stabilized broadband incandescent light source attached to a fiber-optic bundle used to direct the light (Fostec DCR-II with a 1 cm diameter fiber bundle extension from Schott-Fostec LLC, Marlborough, MA and Auburn, NY).

[0124] Method Electron

[0125] Samples were freeze fractured with liquid nitrogen. Imaging was done with a Hitachi S4700 Field Emission microscope.

[0126] Method for Acquiring Transmission Electron Microscopy (TEM) Images

[0127] Samples for TEM analysis were room-temperature ultra-microtomed. Cut thickness was approximately 100 nm. Microtomy-cut direction was chosen to be parallel or nearly parallel to a majority of the interfaces. TEM analysis was performed on a FEI-Osiris TEM, operating at 200 kV. The STEM imaging mode was used. Bright Field (BF), Dark Field (DF), and High Angle Annular Dark Field (HAADF) images were acquired. X-ray microanalysis was performed using a Bruker Super-X quad x-ray SDD (silicon drift detector) and accompanying Espirit quantitative analysis software system.

[0128] Method for Determining Weight% of Inorganic Particles in LbL Etch Stop Coatings “Light Transmissive Layer”

[0129] A layer-by-layer (LbL) spray coater, purchased from Svaya Nanotechnologies (Sunnyvale, CA) and modeled after the system described in US 8,234,998 (Krogman et al.) as well as Krogman et al. Automated Process for Improved Uniformity and Versatility of Layer-by-Layer Deposition, Langmuir 2007, 23, 3137-3141, was used to deposit LbL etch stop coatings on a 12”xl2” glass plate. The coatings were scraped off the plate with a razor blade. The powder samples were analyzed using a TA Instruments Discovery Thermogravimetric Analyzer (TGA) in HiRes mode. The sample was subjected to a heating profile ranging from room temperature (~ 30 °C) to 700 °C in a nitrogen atmosphere, with a heating rate of 20.0 °C / min and a resolution setting of 4.0. Under these conditions, the instrument heats the sample until weight loss is detected, at which point the temperature stabilizes until weight loss diminishes, and then heating recommences. At 700°C the atmosphere was then switched to air and the HiRes heating ramp was continued to 800° C. The weight% residue at 800° C was taken as the weight % of inorganic particles (e.g., metal oxide) in the coating samples.

[0130] Standard Thickness Black

[0131] A microstructured film was prepared as described in “Method to Make Microstructured Film (Step 1)”

[0132] The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer (Step 2)” The light absorbing layer was etched as described in “Method to Selectively Remove the Light Absorbing Cover Layer (Step 4B)” where the film was carried through the reaction zone at a rate of 1 ft / min, corresponding to an approximate exposure time of 300 seconds.

[0133] The structured film was backfilled as described in “Method to Backfill (Step 5).”

[0134] SEM images revealed that the cover layer was substantially removed from the second side surface.

[0135] Example 1 (EXI): With LbL Etch Stop (“Light Transmissive Layer”)

[0136] A microstructured film was prepared as described in “Method to Make Microstructured Film (Step 1).”

[0137] The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer (Step 2)”. The formulation for the cover layer was 6 bilayers of Cation / Clad Anion followed by 4 bilayers of Cation / Core Anion followed by 6 bilayers of Cation / Clad Anion for a total of 16 bilayers.

[0138] A layer-by-layer etch stop was coated on the microstructured film as described in “Method to Coat a Layer-by-Layer Etch Stop (Light Transmissive Layer) (Step 3).”

[0139] The light transmissive layer was etched away on the horizontal surfaces (“lands”) using the “Method to Selectively Remove Portions of the Layer-by-Layer Etch Stop (Light Transmissive Layer) (Step 4A)”.

[0140] The light absorbing layer cover layer was etched away on the horizontal surfaces (“lands”) using the “Method to Selectively Remove Portions of the Light Absorbing Cover Layer (Step 4B)” where the film was carried through the reaction zone at a rate of 1 ft / min, corresponding to an approximate exposure time of 300 seconds.

[0141] The structured film was backfilled as described in “Method to Backfill (Step 5).”

[0142] The angular light transmission profile was measured using the “Method for Measuring the Luminance Profile from a Diffuse Light Source” and is shown in Figure 9B.

[0143] From cross-sectional TEM images acquired using the “Method for Acquiring Transmission Electron Microscopy (TEM) Images”, the thickness of the LbL etch stop (i.e., light transmissive layer) on the more vertical facet (i.e., “first side surface”) was measured to be 168 ± 23 nm (T3) using ImageJ software, while the thickness of the LbL etch stop (i.e., light transmissive layer) on the more sloped facet (i.e., second side surface) was measured to be 83 ± 11 nm (T4) using Image J software.

[0144] Example 2 (EX2): Light Absorbing Cover Laver with Extra Thick Outermost Cladding

[0145] A microstructured film was prepared as described in “Method to Make Microstructured Film (Step 1).”

[0146] The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer (Step 2).” The formulation for the cover layer was 6 bilayers of Cation / Clad Anion followed by 4 bilayers of Cation / Core Anion followed by 30 bilayers of Cation / Clad Anion, for a total of 40 bilayers.

[0147] The light absorbing cover layer was etched away on the horizontal surfaces (“lands”) as described in the “Method to Selectively Remove the Light Absorbing Cover Layer (Step 4B)” where the film was carried through the reaction zone at a rate of 0.5 ft / min, corresponding to an approximate exposure time of 600 seconds.

[0148] The structured film of Step 4 was backfilled as described in “Method to Backfill (Step 5).” The angular light transmission profile was measured using the “Method for Measuring the Luminance Profile from a Diffuse Light Source” and is shown in Figure 9B.

[0149] From cross-sectional SEM images acquired using the “Method for Acquiring Scanning Electron Microscopy (SEM) Images”, the thickness of the light absorbing cover layer on the more vertical facet (i.e., “first side surface”) was measured to be 1965 ± 45 nm (Tl) using ImageJ software, while the thickness of the light absorbing cover layer on the more sloped facet (i.e., second side surface) was measured to be 608 ± 200 nm (T2) using Image J software.

[0150] Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1.1, and that the value could be 1.

[0151] Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially equal” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially equal” will mean about equal where about is as described above. If the use of “substantially parallel” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially parallel” will mean within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees, or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of “substantially aligned” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially aligned” will mean aligned to within 20% of a width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned to within 10% or to within 5% of a width of the objects being aligned.

[0152] All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control.

[0153] Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed:

1. A light control film comprising a structured first major surface opposite a second major surface, the structured first major surface comprising a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves, each structure comprising a first side surface opposite a second side surface, each groove having one or more substantially planar landings joining the corresponding structures; the first side surface substantially orthogonal with a first adj acent landing of the one or more landings, the second side surface making an angle with a second adjacent landing of the one or more landings, the angle greater than about 95 degrees; at least 70% of the first and second side surfaces and at most 30% of the one or more landings coated with a cover layer, the cover layer coated on the first side surface having a first average thickness Tl, the cover layer coated on the second side surface having a second average thickness T2, wherein T1 > T2.

2. The light control film of claim 1, further comprising a planarizing overcoat covering, and substantially planarizing, the structured first major surface.

3. The light control film of claim 2, wherein the planarizing overcoat comprises an optically clear adhesive.

4. The light control film of claim 2, wherein a refractive index of the planarizing overcoat is different from a refractive index of a material comprising the first major surface by greater than about 0.07.

5. The light control film of claim 2, wherein a refractive index of the planarizing overcoat is substantially equal to a refractive index of a material comprising the first major surface.

6. The light control film of claim 1, wherein the plurality of structures comprises linear structures extending substantially across a width direction of the light control film and arranged along an orthogonal length direction of the light control film, each linear structure separated from each adjacent linear structure by a groove of the one or more grooves.

7. The light control film of claim 1, wherein Tl is greater than T2 by at least a factor of 1.1.

8. The light control film of claim 1, wherein the cover layer is light absorbing.

9. The light control film of claim 1, wherein the light absorbing cover layer comprises a poly electrolyte.

10. The light control film of claim 8, wherein the light absorbing cover layer comprises a plurality of light absorbing particles.

11. The light control film of claim 10, wherein the light absorbing particles comprise one or more of a dye, a pigment, and a carbon black.

12. The light control film of claim 8, wherein the light absorbing cover layer has an optical density of greater than about 0.1.

13. A display system comprising the light control film of claim 1 and a display configured to form an image to a viewer, the light control film disposed between the viewer and the display.

14. A display system comprising a display configured to form an image to a viewer, an extended light source, and the light control film of claim 1 , the light control film disposed between the extended light source and the display.

15. The light control film of claim 1, wherein the cover layer comprises a core layer sandwiched between a first cladding layer and a second cladding layer.

16. The light control film of claim 15, wherein the core layer has a first concentration, Cl, of a light absorbing material and the first and second cladding layers have a second concentration, C2, of the light absorbing material, wherein C2<C1, and wherein the core layer comprises 15 vol. % to 90 vol. % of light absorbing material and the first and second cladding layers may each include 0.3 vol. % to 35 vol. % of light absorbing material.

17. The light control film of claim 16, wherein the core layer has an optical density of greater than about 0.1.

18. The light control film of claim 15, wherein thicknesses of the first cladding layer and the core layer on the first side surface are substantially the same as corresponding thicknesses of the of the first cladding layer and the core layer on the second side surface, wherein a thickness of the second cladding layer on the first side surface is greater than a thickness of the second cladding layer on the second side surface.

19. The light control film of claim 1, wherein a transmission profile of the light control film has a peak transmission at a viewing angle having a magnitude greater than or equal to about 10 degrees, and an average transmission percentage across the profile equal to 50% or less of the peak transmission.

20. The light control film of claim 1, wherein a transmission profile of the light control film has a peak transmission at a viewing angle having a magnitude between about 10 degrees and about 30 degrees, and an average transmission percentage across the profile equal to 50% or less of the peak transmission.

Images