Optical laminate and housing for electronic device

Abstract

A housing (185) for an electronic device (170) includes an optical film (100) having optical transmissivity for substantially normally incident light with a band edge separating a first wavelength range and a second wavelength range, the first wavelength range extending from about 400 nm to about 700 nm, and the second wavelength range being at least about 100 nm wide and extending between about 800 nm and about 1100 nm. For substantially normally incident light, the optical film has an average optical reflectance greater than about 90% in the first wavelength range and an average optical transmittance greater than about 80% in the second wavelength range. For at least one frequency within the range of about 0.1 GHz to about 90 GHz, and for substantially normally incident radiation, the optical film transmits at least about 95% of the incident radiation.

Description

Background Art

[0001] An electronic device typically includes a housing that can provide a desired appearance.

Summary of the Invention

[0002] This specification generally relates to an optical laminate that can be included in a housing or cover, and a housing for an electronic device. The housing includes an optical film bonded to a rigid light-transmissive substrate. In some embodiments, the optical film has a high reflectance (e.g., greater than about 90%) in the visible wavelength range, a high transmittance (e.g., greater than about 80%) in the near-infrared wavelength range, a large gradient (e.g., greater than about 2% per nanometer (nm)) separating the visible range and the near-infrared range, and a high transmittance (e.g., at least about 95%) for at least one frequency within the range of about 0.1 gigahertz (GHz) to about 90 GHz. An optical laminate including the optical film and at least one other layer is also provided. The optical layer included in the optical laminate can be, for example, a colored layer or an optical diffusing layer.

[0003] In some aspects of this specification, a housing for an electronic device is provided. The housing includes an optical film bonded to a rigid light-transmissive substrate. The light transmittance of the optical film for light incident substantially perpendicularly and for at least one polarization state has a band edge that separates a first wavelength range and a second wavelength range, the first wavelength range spanning at least about 400 nm to about 700 nm, the second wavelength range being at least about 100 nm wide and being between at least about 800 nm and about 1100 nm. For light incident substantially perpendicularly and for at least one polarization state, the average light reflectivity of the optical film is greater than about 90% in the first wavelength range, and the average light transmittance of the optical film is greater than about 80% in the second wavelength range. Over at least the wavelength range where the light transmittance of the optical film increases from about 10% to about 70%, the best linear fit to the band edge correlating the light transmittance to wavelength has a gradient greater than about 2% / nm. In some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, the optical film transmits at least about 95% of the incident radiation. In some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical film is less than about 0.02, and for radiation incident substantially perpendicularly, the optical film reflects less than about 5% of the incident radiation.

[0004] In some aspects of the present specification, an optical laminate is provided. The optical laminate includes an optical film including a first layer and a second layer of a plurality of alternating polymers disposed on a skin layer, each of the first layer and the second layer having an average thickness of less than about 250 nm, and the skin layer having an average thickness of greater than about 2 micrometers. The first layer, the second layer, and the skin layer are integrally formed with each other. The light transmittance of the optical film for light incident substantially perpendicularly and at least one polarization state has a band edge separating a first wavelength range and a second wavelength range, the first wavelength range extending over at least about 400 nm to about 700 nm, the second wavelength range being at least about 100 nm wide and being between at least about 800 nm and about 1100 nm. For light incident substantially perpendicularly and at least one polarization state, the average light reflectivity of the optical film is greater than about 90% in the first wavelength range, and the average light transmittance of the optical film is greater than about 80% in the second wavelength range. Over a wavelength range in which the light transmittance of at least the optical film increases from about 10% to about 70%, the best linear fit to the band edge correlating the light transmittance to the wavelength has a gradient of greater than about 2% / nm. The optical laminate includes an optical layer disposed on the optical film and having a spread substantially the same as that of the optical film, and for light incident substantially perpendicularly and at least one polarization state, the light absorption rate of the optical layer is at least 20% higher for a first wavelength within the first wavelength range than for a second wavelength within the first wavelength range. The optical laminate has a light transmittance of greater than about 60% for a third wavelength within the second wavelength range for light incident substantially perpendicularly and at least one polarization state.

[0005] In some aspects of this specification, an optical laminate is provided that includes an optical film bonded to a rigid light-transmissive substrate. The optical film includes a plurality of polymer layers, sequentially numbered from 1 to N, disposed along at least a portion of the thickness of the optical film, where N is an integer greater than about 100. The plurality of polymer layers includes polymer end layers at both ends thereof. A plot of the average layer thickness versus the layer number of the plurality of polymer layers includes a first bend region that separates a left region including at least N1 sequentially arranged polymer layers having lower layer numbers from an intermediate region including at least N2 sequentially arranged polymer layers having higher layer numbers. N1 is an integer greater than about 50, and N2 is an integer greater than about 10. A linear fit to at least N1 sequentially arranged polymer layers in the left region has an r-squared value greater than about 0.8 and a positive linear gradient of greater than about 0.04 nm per layer number. A linear fit to at least N2 sequentially arranged polymer layers in the intermediate region has an r-squared value greater than about 0.8 and a negative linear gradient of greater than about 0.05 nm per layer number.

[0006] These and other aspects will become apparent from the following detailed description. However, in no event should this brief summary be construed as limiting the subject matter of the claims.

Brief Description of the Drawings

[0007]

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Best Mode for Carrying Out the Invention

[0008] In the following description, reference is made to the accompanying drawings, which form a part of this specification and in which various embodiments are shown by way of example. The drawings are not necessarily to scale. It should be understood that other embodiments can be conceived and practiced without departing from the scope or spirit of the present disclosure. Accordingly, the following embodiments for carrying out the invention are not to be construed in a limiting sense.

[0009] An electronic device typically includes a housing. The housing is typically the outermost layer of the device and is typically visible to the user of the device. In some cases, it is desirable for the housing to be transparent to radio waves (e.g., cellular phone signals). A metallic appearance may also be desired. For example, it may be desirable for the cover of the electronic device to have a metallic appearance, or for the logo or emblem on the electronic device to have a metallic appearance. However, metal is not transparent to radio waves. The housings and optical laminates described herein can, in some embodiments, provide a metallic appearance while being substantially transparent to radio waves (e.g., 5G wavelengths). For example, the housing can include a back cover that includes a glass layer and an optical film bonded to the glass layer, and the optical film can have a high specular reflection, resulting in a metallic appearance. In some embodiments, an electronic device such as a smartphone includes an infrared sensor / transmitter for one or more of proximity detection, light detection and ranging (lidar), or temperature detection (e.g., for camera autofocus). In some embodiments, the optical film is substantially transparent to near-infrared wavelengths used by such sensors / transmitters while having high reflectivity over the visible wavelength range of at least 450 nm to 650 nm or 400 nm to 700 nm.

[0010] FIG. 1 is a schematic cross-sectional view of an electronic device 170 according to some embodiments. The illustrated electronic device 170 includes a display component 175 having a light output region 186 for displaying an image 455 to an observer 460. The electronic device 170 includes a front cover 184 and a back cover 180, and a frame 182 extending between the front cover 184 and the back cover 180. The front cover 184 is disposed on the front side of the electronic device 170 facing the observer 460, and the back cover is on the rear side of the electronic device 170 on the opposite side facing away from the observer 460. The housing 185 of the electronic device 170 includes the back cover 180 and the frame 182, and can optionally be considered to include the front cover 184. In some embodiments, the housing can be a single back cover having a curved three-dimensional design. As further described elsewhere herein, the housing 185 includes an optical film that can be included in a portion of the back cover 180 and / or the frame 182 and / or the front cover 184. In embodiments where the electronic device has a light output region, it is typically preferred that the optical film does not substantially overlap the light output region 186. For example, the optical film may cover less than 10% of the light output region 186, or in some embodiments, the optical film does not cover any of the light output region 186. The optical film can be, for example, a mirror film included to provide a desired appearance to the housing 185, and it is typically not desirable for such a film to cover a portion of the light output region 186.

[0011] In some embodiments, the electronic device includes a visible light element 166 adapted to receive or transmit light. For example, the visible light element 166 may include a camera, a camera flash, or both. In some embodiments, the housing 185 includes a window 168 to allow transmission of visible light into and out of the housing. The optical film typically does not substantially overlap with the window 168. In some embodiments, the electronic device includes an infrared (IR) light element 169 adapted to receive or transmit infrared light. The infrared light is typically near-infrared light (wavelengths from about 700 nm to about 2000 nm). The near-infrared (NIR) light of interest typically has a wavelength from, for example, about 800 nm to about 1500 nm, or up to about 1300 nm, or up to about 1200 nm, or up to about 1100 nm. In some embodiments, the housing, or the portion of the housing covering the IR light element 169, is substantially transmissive to NIR wavelengths. In some embodiments, the optical film included within the housing 185 covers, or substantially covers, the IR light element 169. In some embodiments, the optical film is substantially opaque to NIR wavelengths.

[0012] In some embodiments, the electronic device 170 is configured to transmit and / or receive radiation at an operating frequency in the range of about 0.1 GHz to about 90 GHz. For example, the electronic device 170 may be a 5G mobile phone. In such embodiments, it is typically desirable for at least a portion of the housing 185 (e.g., the back cover 180) to be substantially transmissive at the operating frequency. Thus, it is typically desirable for the optical film to be transmissive at the operating frequency. In some embodiments, the inside of the housing may support transmitters and receivers of signals in the form of antennas that are patterned or otherwise arranged on the inside of the back cover.

[0013] FIG. 2 is a schematic cross-sectional view of a back cover 180 according to some embodiments. The back cover 180 includes a rigid light-transmissive substrate 181. A “rigid” substrate is a substrate that is sufficiently rigid such that when held horizontally by the edges of the substrate (the short edges in the case of a substantially rectangular substrate), the substrate does not substantially flex (e.g., the vertical flexure is less than about 1 / 4 of the length of the long edge). For example, a glass sheet and a sufficiently thick polymer (e.g., polycarbonate, polymethyl methacrylate, or blends thereof) sheet are typically rigid substrates, while a flexible film is not a rigid substrate. In some embodiments, the substrate 181 is a glass substrate having an average thickness of at least 0.5 mm. A “light-transmissive” substrate is a substrate having an average light transmittance of greater than 50 percent for non-polarized light incident substantially perpendicularly. In some embodiments, the average light transmittance is greater than about 60 percent, or greater than about 70 percent, or greater than about 80 percent. The back cover 180 includes an optical film 100 disposed on the substrate 181. In some embodiments, the optical film 100 has a spread that is substantially the same as that of the substrate 181. For example, the optical film 100 may cover at least about 80 percent of the area of the substrate 181. In some embodiments, the optical film 100 optionally covers all of the substrate 181 except for a portion of the edge (e.g., near the frame 182). The optical film 100 typically faces the display component 175, while the substrate 181 faces the opposite side of the display component 175. For example, the back cover 180 may be oriented as shown by the x-y-z coordinate system of FIGS. 1 and 2.

[0014] In the illustrated embodiment, the back cover 180 includes an optional adhesive layer 183, an optional optical layer 210, and an optional optical layer 210'. For example, an additional adhesive layer can be optionally included between the optical layer 210 and the optical film 100. In some embodiments, the optical layer 210 and / or 210' is a coating applied to the substrate 181 or the optical film 100. The optical layer 210 or 210' may be, for example, a color filter such as a layer colored with a dye or pigment or an ink coating, or may be, for example, an optical diffuser. Suitable dyes or pigments for achieving the desired color are known in the art. In some embodiments, one of the optical layers 210 and 210' is a color filter and the other is an optical diffuser. For example, the optical layer 210' may be an optical diffuser, the optical layer 210 may be a color filter, or vice versa. The color filter may be included, for example, to give the housing a colored metallic appearance, and the optical diffuser layer may be included to adjust the appearance of the housing. In some embodiments, one or both of the optical layers 210, 210' may be a patterned layer (e.g., a patterned light-absorbing layer). For example, the optical layer may be an ink layer that blocks a portion of the optical film 100 and leaves other portions uncoated. The ink layer can have a light absorption rate of at least 20% for at least one visible wavelength (e.g., wavelengths in the range of 400 nm to 700 nm). An optional uncoated portion 293 is schematically shown in FIG. 2 for the layer 210. The uncoated portion 293 can define, for example, a logo or an emblem. In some embodiments, one of the optical layers 210, 210' is omitted. When the optical layer 210 and / or 210' is included, the optical film 100 having the optical layer 210 and / or 210' can be described as an optical laminate 200. The back cover 180 may optionally include additional optical layer(s) disposed on the optical film 100 on the opposite side of the substrate 181. Such additional optical layer(s), if included, can be considered part of the optical laminate 200. Other optical layers that can be included in the optical laminate 200 include, for example, a texture layer.

[0015] Alternatively, the back cover 180 can be regarded as an optical laminate that can be used for other applications. For example, the optical laminate can be used as a front cover for a non-display device or system. The optical laminate includes an optical film 100 bonded to a rigid light-transmissive substrate 181, and the optical film can be any of the optical films described herein.

[0016] In some embodiments, the optical film 100 is a multilayer optical film that includes alternating polymer layers. By appropriately selecting the layer thicknesses, such a multilayer optical film can be used to provide desired reflection and transmission in a desired wavelength range. Multilayer optical films and methods of making multilayer optical films are described, for example, in U.S. Patent Nos. 5,882,774 (Jonza et al.), 6,179,948 (Merrill et al.), 6,783,349 (Neavin et al.), 6,967,778 (Wheatley et al.), and 9,162,406 (Neavin et al.). Layer thickness profiles that provide high reflectivity in the visible range, high transmittance in the near-infrared range, and sharp band edges therebetween are further described elsewhere herein.

[0017] FIG. 3 is a schematic cross-sectional view of an exemplary optical film 100 including a plurality of alternating first polymer layers 101 and second polymer layers 102. In the illustrated embodiment, the plurality of alternating first layers 101 and second layers 102 are disposed on skin layers 105 and / or 105'. Optionally, one or both of the skin layers 105 and / or 105' may be omitted. The plurality of alternating first layers 101 and second layers 102 mainly reflect and transmit light by light interference and may be referred to as optical layers or interference layers. The optical film 100 can include a single packet of first layers 101 and second layers 102 that can be referred to as interference layers, or alternatively, two or more packets separated by optically thick layers 104 that may have an average thickness Tb of greater than about 500 nm or greater than about 1 micrometer. The optical film, or the interference layer of the optical film, can be described as mainly reflecting or transmitting light by light interference when the reflectance and transmittance can be reasonably explained by light interference or can be reasonably and accurately modeled as arising from light interference. Adjacent pairs of interference layers having different refractive indices reflect light by light interference when the pair has a combined optical thickness (physical thickness multiplied by refractive index) that is one-half of the wavelength of light. The refractive index used to determine the optical thickness can be a fixed reference wavelength (e.g., 532 nm or 633 nm). The interference layers typically have a physical thickness of less than about 500 nanometers, or less than about 300 nanometers, or less than about 250 nanometers. The skin layers typically have an optical thickness that is too large to mainly reflect and transmit light by light interference and can be referred to as non-interference layers, non-optical layers, or optically thick layers. However, Fresnel reflection from the main surface of the skin layer (e.g., the outermost main surface) can affect the transmission spectrum of the optical film, as further described elsewhere in this specification.

[0018] The thicknesses of the first and second layers that interact can be selected to provide a desired reflection band, and the thickness profile can be selected to include a number of layer pairs having an optical thickness corresponding to the band edge, as further described elsewhere in this specification. The appropriate thickness of the skin layer(s) can be determined by optical modeling, which can, for example, determine a transmission spectrum for a range of skin thicknesses. For example, a skin thickness can be selected that results in reduced optical ringing.

[0019] The average thickness t of the interference layer is shown. In some embodiments, each of the first and second layers has an average thickness of less than about 500 nm, or less than about 250 nm, or less than about 200 nm, or less than about 180 nm, or less than about 200 nm, or within the range of 20 nm to 250 nm, or within the range of 25 nm to 200 nm, or within the range of about 30 nm to about 180 nm. The average thickness refers to the simple average of the thicknesses over a region of the optical film 100. Since the thickness of the layer can be substantially constant (e.g., varying by 10% or less, or 5% or less, or 3% or less), the average thickness is the substantially constant thickness of the layer. In some embodiments, the skin layers 105, 105' have an average thickness of greater than about 2 micrometers, or greater than about 3 micrometers, or greater than about 4 micrometers, or greater than about 5 micrometers, or greater than about 6 micrometers, or greater than about 7 micrometers. In some embodiments, the skin layers 105, 105' have a thickness of less than about 30 micrometers, or less than about 20 micrometers, or less than about 15 micrometers, or less than about 10 micrometers. In some embodiments, the skin layers 105, 105' have an average thickness within the range of, for example, about 2 micrometers to about 15 micrometers, or within the range of about 3 micrometers to about 10 micrometers. In some embodiments, the skin layer 105' has an average thickness within about 20% or less, or within about 15% or less, or within about 10% or less of the average thickness of the skin layer 105.

[0020] As used herein, a second element and a first element that is "formed integrally" mean that the first and second elements are not joined after being manufactured individually, but are manufactured together. Forming integrally includes manufacturing the first element and subsequently manufacturing the second element on the first element. An optical film including multiple layers is formed integrally when the layers are not joined after being manufactured separately, but are manufactured together (e.g., combined as a molten stream and then cast onto a chill roll to form a cast film having each layer, and subsequently the cast film is oriented). In some embodiments, at least the first layer 101, the second layer 102, and the skin layer 105 are formed integrally with each other. In some embodiments, the first layer 101, the second layer 102, the first skin layer 105, and the second skin layer 105' on the opposite side are formed integrally with each other.

[0021] The optical film 100 can include more layers 101 and 102 than those schematically shown in FIG. 3. In some embodiments, the optical film 100 includes a plurality of alternating polymer layers 101 and 102, which are at least 30 in total and mainly transmit and reflect light by light interference. In some embodiments, the optical film 100 includes a plurality of alternating first polymer layers 101 and second polymer layers 102 in a number of 50 to 800, or 400 to 800, or 500 to 800. In some embodiments, only the layers having a thickness of less than about 500 nm or less than about 250 nm in the optical film are the first layer 101 and the second layer 102, and the total number of the alternating first polymer layers 101 and second polymer layers 102 is within the range of 50 to 800, or within the range of 400 to 800, or within the range of 500 to 800.

[0022] The optical film of the present description can be made using any suitable light-transmissive material, but in many cases it is beneficial to use a low-absorbing polymer material. Using such a material, the absorption rate of the micro-layer laminate over the visible and infrared wavelengths can be reduced or made negligible, so that the sum of the reflectance and transmittance for the laminate (or the optical film of which the laminate is a part) is approximately 100% for any given wavelength and any particular angle of incidence and state of polarization, i.e., R + T ≈ 100% or R ≈ 100% - T. Suitable materials for the alternating first layer 101 and second layer 102, skin layers 105, 105', and layer 104 include, for example, polyethylene naphthalate (PEN), copolymers containing PEN and polyester (e.g., polyethylene terephthalate (PET) or dibenzoic acid), glycol-modified polyethylene terephthalate, polycarbonate (PC), poly(methyl methacrylate) (PMMA), or blends of materials of these classes. In some embodiments, the first layer 101 includes PEN and the second layer 102 includes PMMA. In some embodiments, the first layer 101 includes PEN and the second layer 102 includes a polymer blend of glycol-modified copolyester and polycarbonate. Such polymers have a low absorption rate in the target visible and NIR wavelength ranges and in the target 5G frequency range.

[0023] The light transmission characteristics and reflection characteristics of the optical film may be specified for light incident substantially perpendicularly. Light incident substantially perpendicularly is light that is close enough to being incident perpendicularly on the optical film that the transmittance and reflectance of the light incident substantially perpendicularly differ only negligibly from the transmittance and reflectance of the light incident perpendicularly on the optical film. In some embodiments, the light incident substantially perpendicularly may be within 20 degrees, within 10 degrees, or within 5 degrees of normal incidence, or may be normal incidence or nominally normal incidence. The transmission and reflection characteristics of the optical film may alternatively or additionally be specified for radiation (e.g., radio frequency) incident substantially perpendicularly on the optical film. It can be understood that radiation incident substantially perpendicularly means that the line from the radiation source facing the optical film to the optical film is substantially perpendicular to the optical film. The light or radiation 50 incident substantially perpendicularly is schematically shown in FIG. 3. Radio frequency radiation can be assumed to be unpolarized, unless otherwise indicated. The light transmission characteristics and reflection characteristics of the optical film can be specified for at least one polarization state. For example, the optical characteristics may be specified for a first polarization state 171, or may be specified for a first polarization state 171 and a second polarization state 172 that are orthogonal.

[0024] In some embodiments, the optical film 100 is reflective in a first wavelength range (e.g., spanning at least about 430 nm to about 680 nm, or spanning about 400 nm to about 700 nm) for at least one polarization state. For example, in some embodiments, for light incident substantially perpendicularly and for at least one polarization state, the average light reflectance of the optical film is greater than about 90%, or greater than about 95%, or greater than about 97%, or greater than about 98% in the first wavelength range. The average light transmittance (respectively, light reflectance) is the unweighted average of the light transmittance (respectively, light reflectance) in a specific wavelength range. In some embodiments, for light incident substantially perpendicularly and for at least one polarization state, the light reflectance of the optical film is greater than about 90%, or greater than about 95%, or greater than about 97%, or greater than about 98% for each wavelength within the first wavelength range.

[0025] High reflectivity can be achieved by increasing the number of interference layers that reflect light in a predetermined wavelength range. Optical films having high reflectivity are described in International Application Publication No. 2020 / 053832 (Fabick et al.) and U.S. Patent Application Publication No. 2020 / 0183065 (Hagg et al.). In some embodiments, the optical film 100 is transmissive in a second wavelength range (e.g., spanning at least about 1000 nm to about 1200 nm, or having a width of at least 100 nm and being between about 800 nm and about 1200 nm or between about 800 nm and about 1100 nm, or having a width of at least about 250 nm and being between about 800 nm and about 1300 nm or between about 800 nm and about 1200 nm). For example, in some embodiments, for light incident substantially perpendicularly and for at least one polarization state, the average light transmittance of the optical film is greater than about 75%, or greater than about 80%, or greater than about 85%.

[0026] Figure 4 is a schematic plot of the light transmittance 139 of an optical film with respect to light incident substantially perpendicularly, according to some embodiments. The light transmittance of the optical film includes a band edge 125 that separates a first wavelength range 122 and a second wavelength range 126. The band edge region 124 includes at least a wavelength range in which the light transmittance increases from about 10% to about 70% as the wavelength increases. In some embodiments, the light transmittance of the optical film with respect to light incident substantially perpendicularly within the band edge region 124 increases monotonically from at least about 10% to about 70%, or from at least about 10% to about 75%, or from at least about 10% to about 80%, or from at least about 5% to about 80% as the wavelength increases. In some embodiments, the first wavelength range 122 may extend from at least about 450 nm to about 650 nm, or from about 400 nm to about 700 nm. In some embodiments, the second wavelength range 126 extends over about 950 nm to about 1300 nm or about 1200 nm, or is at least about 100 nm wide and is between about 800 nm and 1100 nm (e.g., in the range of about 1000 nm to about 1100 nm), or is at least about 200 nm wide and is between about 800 nm and about 1300 nm or about 800 nm and about 1200 nm. In some embodiments, the first wavelength range and the second wavelength range each have a width of at least 250 nm or at least 300 nm. In some embodiments, the band edge region 124 has a width of 30 nm or less, 20 nm or less, or 15 nm or less. The reflectance R of at least one polarization state is schematically shown as being about 100% minus the light transmittance 139.

[0027] In some embodiments, the difference between the maximum value 137 and the minimum value 834 of the light transmittance of the optical film in the second wavelength range 126 is less than about 30%, or less than about 25%, or less than about 22% (e.g., the maximum value 137 of the light transmittance in the second wavelength range 126 may be about 95% and the minimum value 834 may be about 75% such that the difference is about 20%).

[0028] In some embodiments, the electronic device includes a housing that includes an optical film and an infrared light element 169 adapted to emit and / or receive light at an infrared wavelength 127. Optionally, the optical film is desirably transmissive to the infrared wavelength 127 and reflective to wavelengths near the infrared wavelength 127 (e.g., about 50 nm shorter). In some embodiments, at the infrared wavelength 127, the optical film transmits at least 70% of the light incident substantially perpendicularly, and at a first wavelength 123 between the first wavelength range 122 and the infrared wavelength 127, the optical film transmits 40% - 60% of the light incident substantially perpendicularly. In some embodiments, the first wavelength 123 is within about 60 nm, or about 50 nm, or about 40 nm, or about 30 nm, or about 20 nm of the infrared wavelength 127.

[0029] The light transmittance 139 can be for at least one polarization state. For example, the at least one polarization state includes a first polarization state (171) and a second polarization state (172) that are orthogonal. In this case, the light transmittance 139 is the transmittance for each of the first polarization state and the second polarization state. In some embodiments, the at least one polarization state includes the first polarization state 171, and for the light incident substantially perpendicularly having a second polarization state 172 orthogonal to the first polarization state 171, the average light transmittance of the optical film is greater than about 80% in each of the first wavelength range and the second wavelength range. For example, the light transmittance in the second polarization state may be the transmittance 140 schematically shown in FIG. 4.

[0030] In some embodiments, the best linear fit to the band edge correlating light transmittance to wavelength has a slope greater than about 2% / nm, or greater than about 3% / nm, or greater than about 4% / nm, or greater than about 5% / nm, over at least a wavelength range (e.g., band edge region 124) where the light transmittance increases from about 10% to about 70%. The best linear fit 136 is schematically shown in FIG. 4. The best linear fit 136 can be determined as a linear least squares fit to the transmittance as a function of wavelength over at least a wavelength region where the transmittance increases from about 10% to about 70% (e.g., over a wavelength range where the transmittance increases from about 10% to about 70%, or from about 10% to about 75%, or from about 10% to about 80%). In some embodiments, the best linear fit to the band edge correlating light transmittance to wavelength extends over at least a wavelength range where the light transmittance increases from about 10% to about 75% or from about 10% to about 80%. In some embodiments, the best linear fit to the band edge correlating light transmittance to wavelength has a slope greater than about 2% / nm, or greater than about 3% / nm, or greater than about 4% / nm, or greater than about 5% / nm, over at least a wavelength range where the light transmittance increases from about 10% to about 75%. In some embodiments, the best linear fit to the band edge correlating light transmittance to wavelength has a slope greater than about 2% / nm, or greater than about 3% / nm, or greater than about 4% / nm, or greater than about 5% / nm, over at least a wavelength range where the light transmittance increases from about 10% to about 80%.

[0031] The band edge gradient can be adjusted by appropriately selecting the layer thickness profile. The layer thickness profile can also be selected, in some embodiments, to provide a desired transmission spectrum, for example, in combination with a skin thickness selected to reduce ringing. Optical films having sharp band edges are known in the art and are described, for example, in U.S. Patent No. 6,967,778 (Wheatley et al.) and International Application Publication No. 2020 / 053832 (Fabick et al.). Related optical films are described in co-pending U.S. Patent Application No. 63 / 021743, filed May 8, 2020, entitled "Optical Film".

[0032] FIG. 5 is a plot 20 of the average layer thickness versus the layer numbers of a plurality of polymer layers 101, 102, according to some embodiments. The thickness profile can be for the plurality of polymer layers 101, 102 throughout the film or in a packet of the film. FIGS. 6-9 are a portion of the plot of FIG. 5. The layer thickness profile can be selected through appropriate feed block design and processing. For example, the layer thickness profile can be controlled using the axial rod heater power levels within the multilayer feed block described in U.S. Patent No. 6,783,349 (Neavin et al.).

[0033] The average layer thickness profile can be measured using an atomic force microscope (AFM). To reduce measurement errors, the average thickness of the layer can be determined as a moving average. The layers can be numbered from the thinnest layer to the thickest layer, and the moving average can be averaged over 20 layers including 10 layers with lower layer numbers, a specific layer, and 9 layers with higher numbers. Near the ends of the profile, fewer layers are available before or after a specific layer, so fewer layers are used for the moving average. For example, in the case of a film or packet having 325 layers, the average thickness of layer 1 is the average thickness of layers 1 to 10, the average thickness of layer 2 is the average thickness of layers 1 to 11, the average thickness of layer 101 is the average thickness of layers 91 to 110, the average thickness of layer 325 is the average thickness of layers 315 to 325, and the average thickness of layer 324 is the average thickness of layers 314 to 325.

[0034] In some embodiments, the optical film 100 includes a plurality of polymer layers 101, 102 that are arranged along at least a portion of the thickness (z-direction) of the optical film and sequentially numbered from 1 to N, where N is an integer greater than about 100. The plurality of polymer layers 101, 102 includes polymer end layers 22, 23, or 22, 223 at both ends thereof (see, for example, FIG. 3). In some embodiments, the polymer end layers 22, 23, and each layer 101, 102 therebetween have an average thickness of less than about 300 nm. The optical film may optionally include at least one layer 104 (see, for example, FIG. 3) between the polymer end layers 22, 23 having an average thickness tb greater than about 500 nanometers, or within any of the thickness ranges described elsewhere in this specification. Any such layer(s) of any thickness that may be included in the optical film can be considered a separate layer not included in the plurality of polymer layers 101, 102 and may be omitted in the sequential numbering from 1 to N. The numbering from 1 to N may alternately refer to the layers within a single packet. For example, the layers sequentially numbered from 1 to N may be the layers of a first plurality of polymer layers that begin with end layer 223 and end with end layer 22, or begin with end layer 22 and end with end layer 223. In some embodiments, the polymer end layers 22, 223, and each layer 101, 102 therebetween have an average thickness of less than about 300 nm.

[0035] In some embodiments, a plot 20 of the average layer thickness t against the layer numbers of the plurality of polymer layers 101, 102 includes a first bending region 30 that separates a left region 31 including at least N1 sequentially arranged polymer layers having lower layer numbers from an intermediate region 32 including at least N2 sequentially arranged polymer layers having higher layer numbers. A linear fit 41 (see, e.g., FIG. 6) to at least N1 sequentially arranged polymer layers in the left region has an r-squared value 43 greater than about 0.8 and a positive linear gradient 42 with a magnitude greater than about 0.04 nm per layer number. A linear fit 44 (see, e.g., FIG. 7) to at least N2 sequentially arranged polymer layers in the intermediate region 32 has an r-squared value 46 greater than about 0.8 and a negative linear gradient 45 with a magnitude greater than about 0.05 nm per layer number. N1 is an integer greater than about 50 (e.g., at least 47, or at least 49, or at least 50, or at least 51). In some embodiments, N1 is greater than about 100, or greater than about 150, or greater than about 180. N2 is an integer greater than about 10. In some embodiments, N2 is greater than about 15 or greater than about 20.

[0036] In some embodiments, the optical film 100 further includes a second bending region 33 that separates the right region 34 from the intermediate region 32 and includes at least N3 sequentially arranged polymer layers. The polymer layers have higher layer numbers than the polymer layers in the intermediate region. A linear fit 47 (see, e.g., FIG. 8) to at least N3 sequentially arranged polymer layers in the right region has an r-squared value 49 greater than about 0.6 and a positive linear gradient 48 with a magnitude greater than about 1.2 nm per layer number. N3 is an integer greater than about 3 (e.g., at least 3). In some embodiments, N3 is at least about 3, 4, 5, or 6.

[0037] In some embodiments, the optical film 100 includes a plurality of polymer layers 101, 102 including polymer end layers at both ends thereof. The polymer end layers and each layer therebetween may have an average thickness of less than about 300 nm. A plot 20 of the average layer thickness t against the layer numbers of the plurality of polymer layers includes a left region 36 including at least N4 sequentially arranged polymer layers, a first intermediate region 31 including at least N1 sequentially arranged polymer layers, a second intermediate region 32 including at least N2 sequentially arranged polymer layers, and a right region 34 including at least N3 sequentially arranged polymer layers. A linear fit 70 (see, e.g., FIG. 9) to at least N4 sequentially arranged polymer layers in the left region has an r-squared value 72 greater than about 0.8 and a negative linear gradient 71 with a magnitude greater than about 0.04 nm per layer number. A linear fit 41 (see, e.g., FIG. 6) to at least N1 sequentially arranged polymer layers in the first intermediate region 31 has an r-squared value 43 greater than about 0.8 and a positive linear gradient 42 with a magnitude greater than about 0.04 nm per layer number. A linear fit 44 (see, e.g., FIG. 5) to at least N2 sequentially arranged polymer layers in the second intermediate region 32 has an r-squared value 46 greater than about 0.8 and a negative linear gradient 45 with a magnitude greater than about 0.05 nm per layer number. A linear fit 47 (see, e.g., FIG. 8) to at least N3 sequentially arranged polymer layers in the right region 34 has an r-squared value 49 greater than about 0.6 and a positive linear gradient 48 with a magnitude greater than about 1.2 nm per layer number. In some embodiments, N1 is an integer greater than about 50, N2 is an integer greater than about 10, N3 is an integer greater than about 3, and N4 is an integer greater than about 5 (e.g., at least 5). N1, N2, and N3 can be any within the ranges described elsewhere in this specification. In some embodiments, N4 is at least 5, or at least 6, or at least 7. Note that the same region may be referred to as the first region or the second region, or the intermediate region or the left or right region, depending on, for example, other elements or regions being considered.

[0038] In some embodiments, the positive linear gradient 42 of the linear fit 41 has a magnitude greater than about 0.05 nm per layer number, or greater than about 0.06 nm per layer number, or greater than about 0.07 nm per layer number. In some such embodiments, or in other embodiments, the r-squared value 43 of the linear fit 41 is greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95.

[0039] In some embodiments, the negative linear gradient 45 of the linear fit 44 has a magnitude greater than about 0.06 nm per layer number, or greater than about 0.07 nm per layer number, or greater than about 0.08 nm per layer number. In some such embodiments, or in other embodiments, the r-squared value 46 of the linear fit 44 is greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95.

[0040] In some embodiments, the positive linear gradient 48 of the linear fit 47 has a magnitude greater than about 1.4 nm per layer number, or greater than about 1.5 nm per layer number, or greater than about 1.6 nm per layer number. In some such embodiments, or in other embodiments, the r-squared value 49 of the linear fit 47 is greater than about 0.6, or greater than about 0.7, or greater than about 0.8, or greater than about 0.85.

[0041] In some embodiments, the negative linear gradient 71 for the linear fit 70 has a magnitude greater than about 0.1 nm per layer number, or greater than about 0.5 nm per layer number, or greater than about 0.8 nm per layer number, or greater than about 1 nm per layer number, or greater than about 1.2 nm per layer number, or greater than about 1.4 nm per layer number. In some such embodiments, or in other embodiments, the r-squared value of the linear fit 70 is greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95.

[0042] In some embodiments, the first bending region 35 separates the left region 36 from the first intermediate region 31, and the polymer layer in the first intermediate region 31 has a higher layer number than the polymer layer in the left region 36. In some such embodiments, or in other embodiments, the second bending region 30 separates the first intermediate region 31 from the second intermediate region 32, and the polymer layer in the second intermediate region 32 has a higher layer number than the polymer layer in the first intermediate region 31. In some such embodiments, or in other embodiments, the third bending region 33 separates the second intermediate region 32 from the right region 34, and the polymer layer in the right region 34 has a higher layer number than the polymer layer in the second intermediate region 32.

[0043] FIG. 10 is a plot 86 of the average layer thickness versus the layer numbers of a plurality of polymer layers 101, 102 according to some embodiments. The thickness profile can be for the plurality of polymer layers 101, 102 across the entire film or a packet of films. FIGS. 11-12 are a portion of the plot of FIG. 10.

[0044] In some embodiments, the optical film 100 includes a plurality of polymer layers 101, 102 sequentially numbered from 1 to P, which are arranged along at least a portion of the thickness (z-direction) of the optical film and correspond to layers 1 to N sequentially numbered (as described elsewhere, for example). P can be, for example, an integer greater than about 100. The plurality of polymer layers 101, 102 include polymer end layers (for example, layers 22, 223) at both ends thereof. Each of the polymer end layers and the layers therebetween can have an average thickness of less than about 300 nm. A plot 86 of the average layer thickness t against the layer numbers of the plurality of polymer layers 101, 102 includes a first bend region 80 that separates a right region 82 including at least P2 sequentially arranged polymer layers having higher layer numbers from a left region 81 including at least P1 sequentially arranged polymer layers having lower layer numbers. A linear fit 83 (see, for example, FIG. 12) to at least P2 sequentially arranged polymer layers in the right region 82 has an r-squared value 85 greater than about 0.8 and a negative linear gradient 84 with a magnitude of greater than about 0.1 nm per layer number. In some embodiments, P1 is an integer greater than about 50, and P2 is an integer greater than about 10. In some embodiments, P1 is at least 50, or at least 100, or at least 150, or at least 200. In some such embodiments, or in other embodiments, P2 is at least 10, or at least 15, or at least 18.

[0045] In some embodiments, the linear fit 87 (see, e.g., FIG. 11) to at least P1 sequentially arranged polymer layers in the left region 81 has an r-squared value 89 greater than about 0.8 and a positive linear gradient 88 having a magnitude in the range of about 0.01 nm per layer number to about 0.25 nm per layer number. In some embodiments, the linear fit 87 has a positive linear gradient 88 in the range of about 0.02 nm per layer number, or about 0.03 nm per layer number, or about 0.04 nm per layer number to about 0.2 nm per layer number, or up to about 0.15 nm per layer number. In some such embodiments, or in other embodiments, the linear fit 87 has an r-squared value 89 greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95.

[0046] In some embodiments, the negative linear gradient 84 of the linear fit 83 has a magnitude greater than about 0.15 nm per layer number, or greater than about 0.2 nm per layer number, or greater than about 0.22 nm per layer number. In some such embodiments, or in other embodiments, the r-squared value 85 of the linear fit 83 is greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95.

[0047] In some embodiments, the optical film 100 includes a plurality of polymer layers 101, 102 arranged along at least a portion of the thickness of the optical film and sequentially numbered from 1 to N, where N is an integer greater than about 100 or greater than about 200. The plurality of polymer layers includes polymer end layers (e.g., layers 22, 223) at both ends thereof, and each layer between the polymer end layers and the polymer end layers has an average thickness of less than about 300 nm. The optical film can have, for example, a layer thickness profile as shown in FIGS. 13-16.

[0048] FIG. 13 is a plot 110 of the average layer thickness versus the layer number of a plurality of polymer layers 101, 102 according to some embodiments. The thickness profile can be for the plurality of polymer layers 101, 102 throughout the film or in a packet of films. FIGS. 14-16 are a portion of the plot of FIG. 13.

[0049] In some embodiments, the optical film is configured such that, for light 50 incident substantially perpendicularly and at least one polarization state, the light transmittance 130 of the optical film with respect to wavelength (see, e.g., FIG. 20) has a band edge 131. In some embodiments, the band edge 131 is from about 800 nm to about 1100 nm. In some embodiments, a plot 110 of the average layer thickness t versus the layer numbers of the plurality of polymer layers 101, 102 includes a bend region 111 that separates a left region 112 including at least Q1 sequentially arranged polymer layers having lower layer numbers from a right region 113 including at least Q2 sequentially arranged polymer layers having higher layer numbers. A linear fit 114 (see, e.g., FIG. 14) to the at least Q1 sequentially arranged polymer layers in the left region 112 has an r-squared value 116 greater than about 0.8 and a positive linear gradient 115 with a magnitude greater than about 0.04 nm per layer number. A linear fit 117 (see, e.g., FIG. 15) to the at least Q2 sequentially arranged polymer layers in the right region 113 has a negative linear gradient 118 of sufficient magnitude. The best linear fit 132 (see, e.g., FIG. 21) has a gradient 133 greater than about 3% / nm, or greater than about 4% / nm, or within any of the ranges described elsewhere in this specification for the band edge gradient. In some embodiments, the best linear fit 132 has an r-squared value 138 greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95. Q1 is an integer greater than about 100. In some embodiments, Q1 is at least 100, or at least 150, or at least 180. Q2 is an integer greater than about 10. In some embodiments, Q2 is at least 10, or at least 12, or at least 14.

[0050] In some embodiments, the linear fit 117 to at least Q2 sequentially arranged polymer layers in the right region 113 has an r-squared value 119 greater than about 0.8 and a negative linear gradient 118 having a magnitude greater than about 0.1 nm per layer number. In some embodiments, the negative linear gradient 118 of the linear fit 117 has a magnitude greater than about 0.12 nm per layer number, or greater than about 0.14 nm per layer number, or greater than about 0.16 nm per layer number. In some such embodiments or other embodiments, the r-squared value 119 of the linear fit 117 is greater than about 0.8, or greater than about 0.85, or greater than about 0.9.

[0051] In some embodiments, the positive linear gradient 115 of the linear fit 114 has a magnitude greater than about 0.05 nm per layer number, or greater than 0.06 per layer number, or greater than about 0.07 nm per layer number. In some such embodiments or other embodiments, the r-squared value 116 of the linear fit 114 is greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.95.

[0052] In some embodiments, a plot 110 of the average layer thickness t versus the layer number of a plurality of polymer layers includes a bend region 111 that separates a right region 113 including at least 10 sequentially arranged polymer layers having higher layer numbers from a left region 112 including at least 100 sequentially arranged polymer layers having lower layer numbers. A cubic polynomial fit 120 (see, e.g., FIG. 14) to at least 15 sequentially arranged polymer layers including the bend region 111 has an r-squared value 723 greater than about 0.8 and has a positive cubic coefficient 121 and a negative quadratic coefficient 722. In some embodiments, the r-squared value 723 is greater than about 0.85, or greater than about 0.9. In some embodiments, the left region 112 includes at least 150 or at least 180 sequentially arranged polymer layers. In some embodiments, the right region 113 includes at least 12 or at least 14 sequentially arranged polymer layers.

[0053] In some embodiments, the optical film 100 includes a plurality of polymer layers 101, 102 sequentially numbered from 1 to N, where N is an integer greater than about 100 or at least 150, and each of the polymer layers 101, 102 has an average thickness of less than about 300 nm. The optical film 100 may include other layers (e.g., 105, 105', 104) in addition to the polymer layers 101, 102 that are, for example, thicker than about 500 nm. In some embodiments, a plot 110 of the average layer thickness t against the layer numbers of the plurality of polymer layers 101, 102 includes a bent region 111 that includes the thickest polymer layer 724 within the plurality of polymer layers 101, 102 such that the optical film 100, or the plurality of polymer layers 101, 102, has the reflectance and transmittance characteristics described elsewhere herein.

[0054] In some embodiments, the layer thickness profile of region 32, 82, or 113 decreases by increasing the layer number, as described by an exponential function further described elsewhere herein.

[0055] FIG. 17 is a schematic plot of the average layer thickness 321 against the layer number for the m-th layer 328 to the N-th layer 329, according to some embodiments. In some embodiments, the m-th layer 328 within the plurality of polymer layers 101, 102 has an average thickness tm, where m < N, and the average thickness of each polymer layer within the plurality of polymer layers 101, 102 having layer numbers n (m ≦ n ≦ N) is

Equation

Number

Number

[0056] FIG. 18 is a plot of the light transmittance 60 of the optical film 100 versus wavelength according to some embodiments. FIG. 19 is a portion of the plot of FIG. 18 near the band edge 61. The light transmittance 60 can be for light 50 incident substantially perpendicularly having a first polarization state 171. In some embodiments, the optical film is a reflective polarizer that substantially transmits light having a second polarization state 172 orthogonal to the first polarization state 171. In other embodiments, the optical film is a mirror film having a light transmittance similar to the light transmittance 60 of light 50 incident substantially perpendicularly having a second polarization state 172. The layer thickness profile of FIG. 5 for packets that reflect longer wavelengths in an optical film that includes packets that reflect shorter wavelengths can generate the light transmittance 60. The layer thickness profile of FIG. 10 can generate a similar light transmittance. In some embodiments, the optical film 100 or the plurality of polymer layers 101, 102 are substantially non-absorbing, such that the light reflectivity R of the optical film is substantially equal to the value obtained by subtracting the light transmittance of the optical film from 100%.

[0057] In some embodiments, for light 50 incident substantially perpendicularly, and for a first wavelength range W1 spanning from about 400 nm to about 800 nm and a second wavelength range W2 spanning from about 950 nm to about 1300 nm, the plurality of polymer layers 101, 102 or the optical film 100 reflect more than about 80% of the incident light having a first polarization state 171 in the first wavelength range W1. In some embodiments, for each of the first polarization state 171 and the second polarization state 172, more than about 60% of the incident light is transmitted in the second wavelength range W2. In some embodiments, the plurality of polymer layers 101, 102, or the optical film 100 transmit more than about 40% or more than about 50% of the incident light having a second polarization state 172 in the first wavelength range W1. In other embodiments, the plurality of polymer layers 101, 102, or the optical film 100 reflect more than about 80% of the incident light having a second polarization state 172 in the first wavelength range W1. In some embodiments, the plurality of polymer layers 101, 102, or the optical film 100 transmit more than about 70% or more than about 80% of the incident light in the second wavelength range W2 for each of the first polarization state 171 and the second polarization state 172. In some embodiments, for light 50 incident substantially perpendicularly, the optical film 100, or the plurality of polymer layers 101, 102 reflect more than about 80% of the incident light 50 in the first wavelength range W1 for the first polarization state 171 and the orthogonal second polarization state 172. In some such embodiments, or in other embodiments, the plurality of polymer layers 101, 102, or the optical film 100 transmit more than about 60% or more than 70% or more than about 80% of the incident light in the second wavelength range W2 for each of the first polarization state 171 and the second polarization state 172.

[0058] In some embodiments, for light 50 that is substantially vertically incident and has a first polarization state 171, the light transmittance 60 of the optical film with respect to wavelength includes a band edge 61 from about 850 nm to about 950 nm, and over a wavelength range W3 where the light transmittance increases from at least about 10% to at least about 70% (e.g., from about 10% to about 70%, or from about 10% to about 80%, or from about 10% to at least about 80%), the best linear fit 62 (see, e.g., FIG. 19) to the band edge correlating light transmittance with wavelength has a gradient 63 greater than about 3% / nm. In some embodiments, the gradient 63 is greater than about 3.5% / nm, or greater than about 4% / nm, or greater than about 4.5% / nm, or greater than about 5% / nm. In some embodiments, the best linear fit 62 has an r-squared value 64 greater than about 0.8, or greater than about 0.85, or greater than about 0.9, or greater than about 0.93, or greater than about 0.95.

[0059] FIG. 20 is a plot of the light transmittance 130 of the optical film 100 versus wavelength. FIGS. 21 and 22 are portions of the plot of FIG. 20. The light transmittance 130 can be for light 50 that is substantially vertically incident and has a first polarization state 171. In some embodiments, the optical film is a reflective polarizer that substantially transmits light having a second polarization state 172 orthogonal to the first polarization state 171. In other embodiments, the optical film is a mirror film having a light transmittance similar to the light transmittance 130 of light 50 that is substantially vertically incident and has a second polarization state 172. The layer thickness profile of FIG. 13 for packets that reflect longer wavelengths in an optical film that includes packets that reflect shorter wavelengths can generate the light transmittance 130.

[0060] In some embodiments, the plurality of polymer layers 101, 102, or the optical film 100 reflect more than about 80% of the incident light 50 having a first polarization state 171 in a first wavelength range W1, transmit more than about 40%, or more than about 50% of the incident light having a second polarization state 172 orthogonal to the first polarization state in the first wavelength range W1, and transmit more than about 60% of the incident light in a second wavelength range W2 for each of the first polarization state 171 and the second polarization state 172. For the first polarization state 171, the light transmittance 130 of the optical film with respect to wavelength includes a band edge 131 from about 800 nm to about 1100 nm. In some embodiments, the band edge 131 is from about 850 nm to about 950 nm. In some embodiments, the best linear fit 132 (see, e.g., FIG. 19) to the band edge 131 that correlates the light transmittance with wavelength over a wavelength range in which the light transmittance increases by at least about 70% from about 10% along at least the band edge has a gradient 133 greater than about 3% / nm, or within any range described elsewhere for the band edge gradient (e.g., greater than about 4% / nm).

[0061] In some embodiments, the wavelength range W5 (see, e.g., FIG. 21) from a first wavelength λa where the best linear fit 132 is 20% to a second wavelength λb where the best linear fit 132 is 80% is less than about 30 nm wide, or less than about 20 nm wide, or less than about 15 nm wide. In some embodiments, the wavelength range from a minimum wavelength greater than about 600 nm where the transmittance is at least about 20% to a minimum wavelength greater than about 600 nm where the transmittance is at least about 80% is less than about 30 nm wide, or less than about 20 nm wide, or less than about 15 nm wide.

[0062] In some embodiments, for a wavelength range of at least 200 nm width over a light transmittance 130 between a band edge and about 2000 nm or about 1600 nm or about 1300 nm, a quadratic polynomial fit 134 (see, e.g., FIG. 22) has an r-squared value 739 greater than about 0.6 and a minimum light transmittance Tmin of less than about 80%. The wavelength range between the band edge and about 2000 nm or about 1600 nm or about 1300 nm can be, for example, in the range of about 950 nm to about 1200 nm. In some embodiments, the r-squared value 739 is greater than about 0.7, or greater than about 0.75. In some embodiments, the quadratic polynomial fit 134 has a positive quadratic coefficient 781 and a negative linear coefficient 782. In some embodiments, the quadratic polynomial fit 134 has a minimum light transmittance Tmin of less than about 75%. In some embodiments, the minimum light transmittance Tmin is greater than about 60%, or greater than about 65%.

[0063] In some embodiments, for light 50 incident substantially perpendicularly, at least one polarization state, and a third wavelength range W4 (see, e.g., FIG. 23) from a smaller wavelength L1 to a larger wavelength L2, the light transmittance 130 has an average value greater than about 75%, or greater than about 80%, or greater than about 85%, 30 nm ≤ L2 - L1 ≤ 50 nm, and L1 is greater than and within about 20 nm from a wavelength 135 corresponding to about 50% light transmittance along the band edge. In some embodiments, 35 nm ≤ L2 - L1 ≤ 45 nm. In some embodiments, L1 is within about 18 nm or within about 16 nm of the wavelength 135. In some embodiments, the electronic device 170 includes an infrared (IR) light element 169 adapted to receive or transmit infrared light at a wavelength (e.g., about 940 nm) within the wavelength range W4 primarily.

[0064] The linear fits described herein can be linear least-squares fits known in the art. The polynomial fits can likewise be least-squares fits. Such fits minimize the sum of the squares of the residuals, where the residuals are the differences between the data and the fit curve (line or polynomial). A least-squares analysis can be used to determine an r-squared value, sometimes called the coefficient of determination.

[0065] Typically, an optical film (and / or a housing including the optical film) desirably has a high transmittance for at least one frequency in the range of about 0.1 GHz to about 90 GHz. For example, the optical film may be used within a 5G mobile phone housing, and it may be desirable for the optical film to be transmissive to the 5G frequencies used by the mobile phone. In addition to, or instead of, the transmittance of the optical film, the reflectance from the film and / or the loss tangent of the film can be specified.

[0066] The transmittance and reflectance can be determined from the scattering parameters obtained using two-port free-space measurements. For example, the scattering parameter S21, which may be called the insertion loss, can be determined from two-port free-space measurements and can be defined as ten times the base-ten logarithm of the ratio of the transmitted power to the incident power. For example, an insertion loss (S21) of -0.1 dB means that about 97.7% of the incident power passes through the film. As another example, the scattering parameter S11, which may be called the reflection loss, can be determined from two-port free-space measurements and can be defined as ten times the base-ten logarithm of the ratio of the reflected power to the incident power. For example, a reflection loss (S11) of -20 dB means that 1% of the incident power is reflected from the film.

[0067] FIG. 24 is a plot of the transmittance through an exemplary optical film as a function of frequency. The data at low frequencies (less than about 2.5 GHz) were obtained in accordance with the ASTM D4935-18 test standard. Due to measurement errors, some numbers resulted in values slightly exceeding 100%. The remaining data in the plot were obtained using two-port free-space measurements.

[0068] FIGS. 25A and 25B are plots of the reflection loss S11 of an optical film according to some embodiments at two different frequency ranges, obtained using two-port free-space measurements.

[0069] The dielectric properties of the optical film were determined using the split post dielectric resonance cavity method. FIG. 26 is a plot of the real part of the permittivity and the loss tangent (tanδ) as a function of frequency. For example, using the IEC61189-2-721 test standard, the dielectric properties in the frequency range of 1 GHz to 33 GHz can be determined.

[0070] The data shown in FIGS. 24 to 26 relate to films generally fabricated as described in Example 2 of International Application Publication No. 2020 / 053832 (Fabick et al.).

[0071] In some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, the optical film transmits at least about 95%, or at least about 97%, or at least about 98%, or at least about 99% of the incident radiation. In some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, the dielectric loss tangent of the optical film is less than about 0.02, or less than about 0.01, or less than about 0.008, or less than about 0.006. In some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, the optical film reflects less than about 5%, or less than about 2%, or less than about 1% of the incident radiation. In some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the real part of the permittivity of the optical film is about 4 or less, or about 3.5 or less, or about 3.2 or less. The at least one frequency referred to for any of these properties may include the same one or more frequencies as the at least one frequency referred to for any of the other of these properties.

[0072] In some embodiments, combinations of two or more of these properties are within at least one of these ranges. For example, in some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical film is less than about 0.02, and for radiation incident substantially perpendicularly, the optical film reflects less than about 5% of the incident radiation, or the dielectric loss tangent of the optical film is less than about 0.01, and for radiation incident substantially perpendicularly, the optical film reflects less than about 2% of the incident radiation, or the loss tangent of the optical film is less than about 0.006, and for radiation incident substantially perpendicularly, the optical film reflects less than about 1% of the incident radiation.

[0073] In some embodiments, at least one frequency in the range of about 0.1 GHz to about 90 GHz includes at least one frequency within the 5G band defined by 3GPP Release 15, or at least one frequency in the range of about 64 GHz to about 71 GHz. 3GPP refers to the Third Generation Partnership Project, a standards organization that released Release 15 on 5G New Radio (NR) in 2018. In some embodiments, at least one frequency in the range of about 0.1 GHz to about 90 GHz includes at least one frequency in the range of 0.6 - 0.7 GHz, or 2.45 - 2.55 GHz, or 3.3 - 4.2 GHz, or 4.4 - 5 GHz, or 5.9 - 7.1 GHz, or 24 - 29 GHz, or 37 - 50 GHz, or 64 - 71 GHz. In some embodiments, at least one frequency in the range of about 0.1 GHz to about 90 GHz includes at least one frequency in the range of 0.5 - 1 GHz or 2.45 - 90 GHz.

[0074] In some embodiments, the optical laminate includes an optical film 100 and further includes an optical layer 210 (each, 210') disposed on the optical film 100 and having a spread substantially the same as that of the optical film 100. For example, the optical layer 210 (each, 210') may cover at least 60 percent or at least 80 percent of the area of the optical film 100, and / or the optical film 100 may cover at least 60 percent or at least 80 percent of the area of the optical layer 210 (each, 210'). The optical layer 210 or 210' can be, for example, a colored layer (e.g., an ink coating) and / or an optical diffuser. The colored layer can be used to provide a desired color in reflection (e.g., to produce a colored metallic appearance), and optionally, an optical diffusion layer can be included to provide a higher diffuse reflectance that may be desired in some applications. In some embodiments, the optical layer 210 or 210' is substantially light-absorbing for at least one visible wavelength (e.g., a wavelength in the range of 400 nm to 700 nm) (e.g., having an absorbance of at least 20% or at least 40% for light incident substantially perpendicular to at least one polarization state). For example, the optical layer 210 or 210' can be a colored layer that absorbs more at some wavelengths than at other wavelengths.

[0075] FIG. 27 is a schematic plot of the transmittance through an optical layer (e.g., 210 or 210′) according to some embodiments for light incident substantially perpendicular to at least one polarization state. The transmittance can be substantially the same for, e.g., orthogonal polarization states. The absorbance can be approximated as 100% minus the transmittance (ignoring Fresnel reflection at the surface). In some embodiments, for light incident substantially perpendicular and at least one polarization state, the light absorption rate of the optical layer is at least 20%, or at least 30%, or at least 40% higher for a first wavelength in the first wavelength range 122 (e.g., the light absorption rate A1 at the first wavelength λ1) than for a second wavelength in the first wavelength range 122 (e.g., the light absorption rate A2 at the second wavelength λ2). The respective light transmittances T1 and T2 at the first wavelength λ1 and the second wavelength λ2 are shown for light incident substantially perpendicular and at least the first polarization state. In some embodiments, T2 - T1 is at least 20%, or at least 30%, or at least 40%. In some embodiments, for light incident substantially perpendicular and at least one polarization state, the light transmittance T2 of the optical layer is greater than about 70% for the second wavelength λ2, and the light absorption rate A1 of the optical layer is greater than about 40% for the first wavelength λ1. In some embodiments, the optical layer has a light transmittance T3 at a third wavelength λ3 within a second wavelength range 126. In some embodiments, the third wavelength λ3 is about 850 nm or about 940 nm. The optical layer may be patterned (e.g., include a light-absorbing ink printed in a pattern). In this case, the light transmittance and light absorption rate of the layer refer to the light transmittance and light absorption rate in the region where the material of the layer is present.

[0076] FIG. 28 is a schematic cross-sectional view of an optical layer 310 (e.g., corresponding to optical layer 210 or 210') according to some embodiments. The optical layer 310 has opposing first and second major surfaces 311 and 312 and includes a plurality of particles 320 dispersed therebetween across the layers. The optical layer 310 may alternatively be referred to as an optical diffusing layer and includes a polymeric material 330 that binds the particles together to form a plurality of particle aggregates 340 that define a plurality of voids 370 therebetween. In some embodiments, the plurality of particles 320 are a plurality of nanoparticles, and the plurality of particle aggregates 340 are a plurality of nanoparticle aggregates. In some embodiments, the particles 320 are silica or include silica. For example, the particles 20 may be silica nanoparticles. In some embodiments, in a plane of the cross-section of the optical layer in the thickness direction of the optical layer 310 (e.g., the x-z plane in the illustrated cross-section), the nanoparticles 320 have an average size of about 20 nm to about 150 nm, the average size of the nanoparticle aggregates 340 is about 100 nm to about 1000 nm, and the voids occupy about 5% to about 50% of the area of the plane of the cross-section. Such an optical diffusing layer has been found to provide a substantially high degree of positive transmittance in the infrared range rather than the visible range according to some embodiments. Alternatively or additionally, according to some embodiments, the optical diffusing layer can provide a substantially higher degree of diffusive transmittance in the visible range rather than the infrared range. In some embodiments, the optical layer 310 has an average thickness Td of about 0.1 micrometer to about 20 micrometers, or about 1 micrometer to about 20 micrometers, or about 1.5 micrometers to about 10 micrometers, or about 2 micrometers to about 8 micrometers.

[0077] In some embodiments, the optical layer 310 is formed by coating a mixture of particles, monomers, and a solvent, and then curing and drying the mixture. The monomers cure to form a polymer binder (polymer material 330), binding aggregates of the particles to each other, and the solvent evaporates to form voids between the aggregates. The solvent can evaporate at least partially during curing and / or the subsequent drying process can be used to complete the evaporation of the solvent. In some embodiments, curing and drying include a pre-curing step, then a drying step, then a post-curing step. In some embodiments, the monomers are ultraviolet (UV) curable and a photoinitiator is included in the mixture. The size of the aggregates can be adjusted by varying the UV output used to cure the monomers, with higher output generally resulting in smaller aggregate sizes. It has been found that a relatively small amount of photoinitiator with a relatively high UV output results in small aggregate sizes and a non-fragile layer, while a relatively large amount of photoinitiator can result in a fragile layer. The void fraction can be adjusted by varying the amount of solvent used in the mixture, with higher solvent loading generally resulting in a higher void fraction. In some embodiments, the mixture includes about 20 to about 60 weight percent solids. In some embodiments, the polymer material 330 is a radiation-curable (e.g., UV-curable) polymer or includes such a polymer. In some embodiments, the polymer material 330 is an acrylate or includes an acrylate. In some embodiments, the polymer material 330 is pentaerythritol triacrylate or includes pentaerythritol triacrylate. The related optically diffusive layer is described in co-pending U.S. Provisional Patent Application No. 63 / 021751, filed May 8, 2020, entitled "Optical Films and Stacks Including Optically Diffusive Layer".

[0078] FIG. 28 schematically shows light 50a and 50b incident substantially perpendicularly to the optical layer 310. Light 50a has a wavelength in the visible range (e.g., corresponding to wavelength range 122), and light 50b has a wavelength in the infrared range (e.g., corresponding to wavelength range 126). For light 50a in the visible wavelength range, the layer or film 310 has an average direct transmittance Vs, an average diffuse transmittance Vd, and an average total transmittance Vt (Vt = Vs + Vd). For light 50b in the near-infrared wavelength range, the optical layer or film 310 has an average direct transmittance Is, an average diffuse transmittance Id, and an average total transmittance It (It = Is + Id). In some embodiments, for light 50, 50a, 50b incident substantially perpendicularly, and for the visible wavelength range of about 450 nm to about 650 nm and the infrared wavelength range of about 930 nm to about 970 nm, in the visible wavelength range, the optical layer 310 has an average direct transmittance Vs, and in the infrared wavelength range, the optical layer 310 has an average total transmittance It and an average direct transmittance Is. In some embodiments, Is / It ≧ 0.6 and Is / Vs ≧ 2.5. In some embodiments, Is / Vs ≧ 3. In some embodiments, It / Vt > 1, or It / Vt > 2, or It / Vt > 3. In some embodiments, Is / It ≧ 0.7. When the polarization state of the incident light is not specified, the incident light can be assumed to be unpolarized unless the context clearly indicates otherwise.

[0079] A high diffuse transmittance (e.g., high Vd) corresponds to a high optical haze. In some embodiments, the optical layer 310 has an optical haze of at least about 5%, at least about 10%, or at least about 20%, or at least about 30%. Optical haze is the ratio of the diffuse visual transmittance to the total visual transmittance and can be determined, for example, in accordance with the ASTM D1003-13 test standard.

[0080] Figure 29 is a schematic plot of the transmittance through the optical laminate 200 according to some embodiments for light incident substantially perpendicular to at least one polarization state. The optical laminate can include an optical film described elsewhere herein and an optical layer such as described in FIG. 27, for example. The transmittance can have variations in the near infrared region not shown in the schematic of FIG. 29 (see, e.g., FIG. 4). In some embodiments, the optical laminate 200 has a light transmittance T4 greater than about 60%, or greater than about 70%, or greater than about 75% for wavelengths in a third wavelength range λ3 within the wavelength range of the second wavelength range 126 for light incident substantially perpendicular and for at least one polarization state.

[0081] The optical laminate 200 can have a transmittance, reflectance, and / or loss tangent within any of the ranges described elsewhere for the optical film 100 for at least one frequency in the range of about 0.1 GHz to about 90 GHz. For example, in some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicular, the optical laminate 200 transmits at least about 95%, or at least about 97%, or at least about 98%, or at least about 99% of the incident radiation. As another example, in some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical laminate 200 is less than about 0.02 and, for radiation incident substantially perpendicular, the optical laminate reflects less than about 5%, or less than about 2%, or less than about 1% of the incident radiation. As yet another example, in some embodiments, for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical laminate is less than about 0.02 and, for radiation incident substantially perpendicular, the optical laminate transmits at least about 95% of the incident radiation. The dielectric loss tangent and transmittance can be within the ranges described elsewhere. The reflectance and transmittance of the optical laminate 200 can be determined for radiation incident on the optical film 100 or, if included, on the optical layer 210 or 210'.

[0082] Terms such as "about" will be understood by those skilled in the art in the context in which they are used and described herein. When the use of "about" applied to the size, amount, and quantities representing physical characteristics of a feature part is not otherwise apparent to those skilled in the art in the context in which it is used and described herein, "about" will be understood to mean within 10 percent of a particular value. An amount given as about or approximately a particular value can be exactly that particular value. For example, when not otherwise apparent to those skilled in the art in the context in which it is used and described herein, an amount having a value of about 1 means that the amount has a value between 0.9 and 1.1 and that the value can also be 1.

[0083] All of the reference documents, patents, or patent applications referred to above are hereby incorporated by reference into this specification in their entirety. In the event of any inconsistencies or contradictions between a part of the incorporated reference document and this application, the information in the foregoing description shall prevail.

[0084] It should be understood that the descriptions of the elements in the figures apply equally to the corresponding elements in other figures unless otherwise indicated. Although specific embodiments have been illustrated and described herein, it will be understood by those skilled in the art that various alternative and / or equivalent implementations can replace the specific embodiments illustrated and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations, variations, or combinations of any of the specific embodiments discussed herein. Accordingly, the present disclosure is to be limited only by the claims and their equivalents. Exemplary embodiments of the present disclosure are shown below. [Item 1] A housing for an electronic device, the housing including an optical film bonded to a rigid light transmissive substrate, the light transmittance of the optical film for light incident substantially perpendicularly and for at least one polarization state including a band edge separating a first wavelength range and a second wavelength range, the first wavelength range extending from about 400 nm to about 700 nm, the second wavelength range being at least about 100 nm wide and being between about 800 nm and about 1100 nm, for light incident substantially perpendicularly and for the at least one polarization state, the average light reflectivity of the optical film is greater than about 90% in the first wavelength range, the average light transmittance of the optical film is greater than about 80% in the second wavelength range, and for at least the wavelength range over which the light transmittance of the optical film increases from about 10% to about 70%, the best linear fit to the band edge correlating the light transmittance of the optical film to wavelength has a gradient greater than about 2% / nm, for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, the optical film transmits at least about 95% of the incident radiation. Housing. [Item 2] The housing according to item 1, wherein for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical film is less than about 0.02. [Item 3] The housing according to item 1, wherein for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the real part of the dielectric constant of the optical film is about 4 or less. [Item 4] The optical film is disposed along at least a part of the thickness of the optical film and includes a plurality of polymer layers sequentially numbered from 1 to N, where N is an integer greater than about 100. The plurality of polymer layers includes polymer end layers at both ends thereof. A plot of the average layer thickness versus the layer number of the plurality of polymer layers includes a first bent region that separates a left region including at least N1 sequentially arranged polymer layers having lower layer numbers from an intermediate region including at least N2 sequentially arranged polymer layers having higher layer numbers. N1 is an integer greater than about 50, and N2 is an integer greater than about 10. A linear fit to the at least N1 sequentially arranged polymer layers in the left region has an r-squared value greater than about 0.8 and a positive linear gradient with a magnitude greater than about 0.04 nm per layer number. A linear fit to the at least N2 sequentially arranged polymer layers in the intermediate region has an r-squared value greater than about 0.8 and a negative linear gradient with a magnitude greater than about 0.05 nm per layer number. The housing according to item 1. [Item 5] The at least one polarization state includes a first polarization state and a second polarization state that are orthogonal to each other. The housing according to item 1. [Item 6] The at least one polarization state includes a first polarization state. For light incident substantially perpendicularly having a second polarization state orthogonal to the first polarization state, the average light transmittance of the optical film is greater than about 80% in each of the first wavelength range and the second wavelength range. The housing according to item 1. [Item 7] The at least one frequency in the range of about 0.1 GHz to about 90 GHz includes at least one frequency within the 5G band defined by 3GPP Release 15 or at least one frequency in the range of about 64 GHz to about 71 GHz. The housing according to item 1. [Item 8] The optical laminate includes the optical film and further includes an optical layer disposed on the optical film and having substantially the same spread as the optical film. The optical layer is substantially light-absorbing for at least one visible wavelength. The housing according to item 1. [Item 9] A housing for an electronic device, wherein the housing includes an optical film bonded to a rigid light-transmissive substrate, and the light transmittance of the optical film for light incident substantially perpendicularly and for at least one polarization state includes a band edge that separates a first wavelength range and a second wavelength range, the first wavelength range spanning from about 400 nm to about 700 nm, the second wavelength range being at least about 100 nm wide and being between about 800 nm and about 1100 nm, and for light incident substantially perpendicularly and for the at least one polarization state, the average light reflectance of the optical film is greater than about 90% in the first wavelength range, the average light transmittance of the optical film is greater than about 80% in the second wavelength range, and the best linear fit to the band edge correlating the light transmittance of the optical film to wavelength over at least the wavelength range where the light transmittance of the optical film increases from about 10% to about 70% has a gradient greater than about 2% / nm, and for at least one frequency in the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical film is less than about 0.02, for radiation incident substantially perpendicularly, the optical film reflects less than about 5% of the incident radiation, A housing. [Item 10] An optical laminate, an optical film including a first layer and a second layer of a plurality of alternating polymers disposed on a skin layer, each of the first layer and the second layer having an average thickness of less than about 250 nm, the skin layer having an average thickness of greater than about 2 micrometers, the first layer, the second layer, and the skin layer being integrally formed with each other, and the light transmittance of the optical film for light incident substantially perpendicularly and for at least one polarization state including a band edge that separates a first wavelength range and a second wavelength range, the first wavelength range spanning from about 400 nm to about 700 nm, the second wavelength range being at least about 100 nm wide and being between about 800 nm and about 1100 nm, and for light incident substantially perpendicularly and for the at least one polarization state, the average light reflectance of the optical film is greater than about 90% in the first wavelength range, The average light transmittance of the optical film is more than about 80% in the second wavelength range, and the best linear fit to the band edge correlating the light transmittance of the optical film to wavelength over at least the wavelength range in which the light transmittance of the optical film increases from about 10% to about 70% has a gradient of more than about 2% / nm, an optical film, An optical layer disposed on the optical film and having a spread substantially the same as that of the optical film, wherein the light absorption rate of the optical layer is at least 20% higher for a first wavelength within the first wavelength range than for a second wavelength within the first wavelength range, and the optical laminate has a light transmittance of more than about 60% for a third wavelength within the second wavelength range, for light incident substantially perpendicularly and the at least one polarization state, an optical layer, An optical laminate comprising the same. [Item 11] The optical laminate according to Item 10, wherein the third wavelength is about 940 nm. [Item 12] The optical film includes a plurality of polymer layers including polymer end layers at both ends thereof, the polymer end layers and each layer therebetween have an average thickness of less than about 300 nm, and a plot of the average layer thickness against the layer numbers of the plurality of polymer layers is A left region including at least N4 sequentially arranged polymer layers, where N4 is an integer greater than about 5, A first intermediate region including at least N1 sequentially arranged polymer layers, where N1 is an integer greater than about 50, A second intermediate region including at least N2 sequentially arranged polymer layers, where N2 is an integer greater than about 10, A right region including at least N3 sequentially arranged polymer layers, where N3 is an integer greater than about 3, and includes The linear fit to the at least N4 successively arranged polymer layers in the left region has an r-squared value greater than about 0.8 and has a negative linear gradient with a magnitude greater than about 0.04 nm per layer number. The linear fit to the at least N1 successively arranged polymer layers in the first intermediate region has an r-squared value greater than about 0.8 and has a positive linear gradient with a magnitude greater than about 0.04 nm per layer number. The linear fit to the at least N2 successively arranged polymer layers in the second intermediate region has an r-squared value greater than about 0.8 and has a negative linear gradient with a magnitude greater than about 0.05 nm per layer number. The linear fit to the at least N3 successively arranged polymer layers in the right region has an r-squared value greater than about 0.6 and has a positive linear gradient with a magnitude greater than about 1.2 nm per layer number. The optical laminate according to item 10. [Item 13] A housing for an electronic device, comprising the optical laminate according to any one of items 10 to 12, bonded to a rigid light-transmissive substrate. [Item 14] An optical laminate comprising an optical film bonded to a rigid light-transmissive substrate, the optical film including a plurality of polymer layers sequentially numbered from 1 to N, where N is an integer greater than about 100, the plurality of polymer layers including polymer end layers at both ends thereof, and a plot of the average layer thickness against the layer number of the plurality of polymer layers includes a first bend region separating a left region including at least N1 successively arranged polymer layers having a lower layer number from an intermediate region including at least N2 successively arranged polymer layers having a higher layer number, where N1 is an integer greater than about 50, N2 is an integer greater than about 10, the linear fit to the at least N1 successively arranged polymer layers in the left region has an r-squared value greater than about 0.8 and has a positive linear gradient with a magnitude greater than about 0.04 nm per layer number, and the linear fit to the at least N2 successively arranged polymer layers in the intermediate region has an r-squared value greater than about 0.8 and has a negative linear gradient with a magnitude greater than about 0.05 nm per layer number. [Item 15] For light incident substantially perpendicularly and for a first wavelength range from about 400 nm to about 800 nm and a second wavelength range from about 950 nm to about 1300 nm, the plurality of polymer layers reflecting more than about 80% of the incident light having a first polarization state in the first wavelength range, transmitting more than about 40% of the incident light having a second polarization state orthogonal to the first polarization state in the first wavelength range, transmitting more than about 60% of the incident light in the second wavelength range for each of the first polarization state and the second polarization state, The optical laminate according to item 14.

Claims

Claim 1 A housing for an electronic device, wherein the housing includes an optical film bonded to a rigid light-transmissive substrate, and the light transmittance of the optical film for light incident substantially perpendicularly and for at least one polarization state includes a band edge separating a first wavelength range and a second wavelength range, the first wavelength range extending from about 400 nm to about 700 nm, the second wavelength range being at least about 100 nm wide and being between about 800 nm and about 1100 nm, and for light incident substantially perpendicularly and for the at least one polarization state, the average light reflectance of the optical film is greater than about 90% in the first wavelength range, the average light transmittance of the optical film is greater than about 80% in the second wavelength range, and the best linear fit to the band edge correlating the light transmittance of the optical film to wavelength extends over a wavelength range in which the light transmittance of the optical film increases from about 10% to about 70% and has a gradient greater than about 2% / nm, and for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, the optical film transmits at least about 95% of the incident radiation, the optical film includes a plurality of polymer layers arranged along at least a portion of the thickness of the optical film and sequentially numbered from 1 to N, the plurality of polymer layers being interference layers that reflect and transmit light by light interference, N being an integer greater than about 100, the plurality of polymer layers including polymer end layers at both ends thereof, and a plot of the average layer thickness versus the layer number of the plurality of polymer layers includes a first bending region separating a left region including at least N1 sequentially arranged polymer layers having a lower layer number from an intermediate region including at least N2 sequentially arranged polymer layers having a higher layer number, N1 being an integer greater than about 50, N2 being an integer greater than about 10, the linear fit to the at least N1 sequentially arranged polymer layers in the left region having an r-squared value greater than about 0.8 and a positive linear gradient greater than about 0.04 nm per layer number, and the linear fit to the at least N2 sequentially arranged polymer layers in the intermediate region having an r-squared value greater than about 0.8 and a negative linear gradient greater than about 0.05 nm per layer number, A housing. Claim 2 For at least one frequency within the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical film is less than about 0.02, the housing according to claim 1.

3. For at least one frequency within the range of about 0.1 GHz to about 90 GHz, the real part of the dielectric constant of the optical film is about 4 or less, the housing according to claim 1.

4. The at least one polarization state includes a first polarization state and a second polarization state that are orthogonal, the housing according to claim 1.

5. The at least one polarization state includes a first polarization state, and for light incident substantially perpendicularly having a second polarization state orthogonal to the first polarization state, the average light transmittance of the optical film is more than about 80% in each of the first wavelength range and the second wavelength range, the housing according to claim 1.

6. The at least one frequency within the range of about 0.1 GHz to about 90 GHz includes at least one frequency within the 5G band defined by 3GPP Release 15, or at least one frequency within the range of about 64 GHz to about 71 GHz, the housing according to claim 1.

7. The optical laminate includes the optical film, and further includes an optical layer disposed on the optical film and having substantially the same spread as the optical film, and the optical layer is substantially light-absorbing for at least one visible wavelength, the housing according to claim 1.

8. A housing for an electronic device, the housing includes an optical film bonded to a rigid light-transmissive substrate, and the light transmittance of the optical film for light incident substantially perpendicularly and at least one polarization state includes a band edge that separates a first wavelength range and a second wavelength range, the first wavelength range spans from about 400 nm to about 700 nm, the second wavelength range is at least about 100 nm wide and is between about 800 nm and about 1100 nm, and for light incident substantially perpendicularly and the at least one polarization state, the average light reflectance of the optical film is more than about 90% in the first wavelength range, The average light transmittance of the optical film is greater than about 80% in the second wavelength range, and the best linear fit to the band edge correlating the light transmittance of the optical film to wavelength over at least the wavelength range in which the light transmittance of the optical film increases from about 10% to about 70% has a gradient greater than about 2% / nm, and for at least one frequency within the range of about 0.1 GHz to about 90 GHz, the dielectric loss tangent of the optical film is less than about 0.02, for radiation incident substantially perpendicularly, the optical film reflects less than about 5% of the incident radiation, the optical film includes a plurality of polymer layers arranged along at least a portion of the thickness of the optical film and sequentially numbered from 1 to N, the plurality of polymer layers being interference layers that reflect and transmit light by light interference, N being an integer greater than about 100, the plurality of polymer layers including polymer end layers at both ends thereof, and a plot of the average layer thickness versus the layer number of the plurality of polymer layers includes a first bend region separating a left region including at least N1 sequentially arranged polymer layers having lower layer numbers from an intermediate region including at least N2 sequentially arranged polymer layers having higher layer numbers, N1 being an integer greater than about 50, N2 being an integer greater than about 10, the linear fit to the at least N1 sequentially arranged polymer layers in the left region having an r-squared value greater than about 0.8 and a positive linear gradient greater than about 0.04 nm per layer number, and the linear fit to the at least N2 sequentially arranged polymer layers in the intermediate region having an r-squared value greater than about 0.8 and a negative linear gradient greater than about 0.05 nm per layer number, Housing. **Claim 9** An optical laminate, An optical film comprising a first layer and a second layer of a plurality of alternating polymers disposed on a skin layer, wherein each of the first layer and the second layer has an average thickness of less than about 250 nm, the skin layer has an average thickness of greater than about 2 micrometers, the first layer, the second layer, and the skin layer are integrally formed with each other, and the light transmittance of the optical film for light incident substantially perpendicularly and at least one polarization state includes a band edge separating a first wavelength range and a second wavelength range, the first wavelength range extends from about 400 nm to about 700 nm, the second wavelength range is at least about 100 nm wide and is between about 800 nm and about 1100 nm, and for light incident substantially perpendicularly and the at least one polarization state, the average light reflectivity of the optical film is greater than about 90% in the first wavelength range, the average light transmittance of the optical film is greater than about 80% in the second wavelength range, and over at least the wavelength range where the light transmittance of the optical film increases from about 10% to about 70%, the best linear fit to the band edge correlating the light transmittance of the optical film to wavelength has a gradient greater than about 2% / nm, an optical film that transmits at least about 95% of the incident radiation for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly, an optical layer disposed on the optical film and having substantially the same spread as the optical film, wherein for light incident substantially perpendicularly and the at least one polarization state, the light absorption rate of the optical layer is at least 20% higher for a first wavelength within the first wavelength range than for a second wavelength within the first wavelength range, and the optical laminate has a light transmittance of greater than about 60% for a third wavelength within the second wavelength range for light incident substantially perpendicularly and the at least one polarization state, comprising, the optical film includes a plurality of polymer layers including polymer end layers at both ends thereof, the plurality of polymer layers are interference layers that reflect and transmit light by light interference, the polymer end layers and each layer therebetween have an average thickness of less than about 300 nm, and the plot of the average layer thickness against the layer number of the plurality of polymer layers is including at least N4 successively arranged polymer layers, where N4 is an integer greater than about 5, a left region, and including at least N1 successively arranged polymer layers, where N1 is an integer greater than about 50, a first intermediate region, and including at least N2 successively arranged polymer layers, where N2 is an integer greater than about 10, a second intermediate region, and including at least N3 successively arranged polymer layers, where N3 is an integer greater than about 3, a right region, and the left region, the first intermediate region, the second intermediate region, and the right region are formed in this order, and a linear fit to the at least N4 successively arranged polymer layers in the left region has an r-squared value greater than about 0.8 and a negative linear gradient with a magnitude greater than about 0.04 nm per layer number, a linear fit to the at least N1 successively arranged polymer layers in the first intermediate region has an r-squared value greater than about 0.8 and a positive linear gradient with a magnitude greater than about 0.04 nm per layer number, a linear fit to the at least N2 successively arranged polymer layers in the second intermediate region has an r-squared value greater than about 0.8 and a negative linear gradient with a magnitude greater than about 0.05 nm per layer number, and a linear fit to the at least N3 successively arranged polymer layers in the right region has an r-squared value greater than about 0.6 and a positive linear gradient with a magnitude greater than about 1.2 nm per layer number. Optical laminate.

10. The optical laminate according to claim 9, wherein the third wavelength is about 940 nm.

11. A housing for an electronic device, including the optical laminate according to claim 9 or 10 bonded to a rigid light-transmissive substrate.

12. An optical laminate including an optical film bonded to a rigid light-transmissive substrate, wherein the optical film includes a plurality of polymer layers sequentially numbered from 1 to N, disposed along at least a portion of the thickness of the optical film, the plurality of polymer layers being interference layers that reflect and transmit light by light interference, N being an integer greater than about 100, the plurality of polymer layers including polymer end layers at both ends thereof, and a plot of the average layer thickness against the layer number of the plurality of polymer layers includes a first bending region separating a left region including at least N1 sequentially arranged polymer layers having lower layer numbers from an intermediate region including at least N2 sequentially arranged polymer layers having higher layer numbers, N1 being an integer greater than about 50, N2 being an integer greater than about 10, a linear fit to the at least N1 sequentially arranged polymer layers in the left region having an r-squared value greater than about 0.8 and a positive linear gradient of greater than about 0.04 nm per layer number, and a linear fit to the at least N2 sequentially arranged polymer layers in the intermediate region having an r-squared value greater than about 0.8 and a negative linear gradient of greater than about 0.05 nm per layer number. The optical film transmits at least about 95% of the incident radiation for at least one frequency in the range of about 0.1 GHz to about 90 GHz and for radiation incident substantially perpendicularly. Optical laminate. **Claim 13** For light incident substantially perpendicularly and for a first wavelength range spanning from about 400 nm to about 800 nm and a second wavelength range spanning from about 950 nm to about 1300 nm, the plurality of polymer layers reflect more than about 80% of the incident light having a first polarization state in the first wavelength range, transmit more than about 40% of the incident light having a second polarization state orthogonal to the first polarization state in the first wavelength range, and transmit more than about 60% of the incident light in the second wavelength range for each of the first polarization state and the second polarization state. The optical laminate according to claim 12.

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