Optical Films for Display Systems

Abstract

The display system includes a light source that emits blue light, including blue wavelengths, and UV light, including UV wavelengths. A first multilayer optical film (MOF) is disposed between the display panel and the second MOF. The light conversion film receives the emitted blue light and converts it to green and red light. At an incidence angle of less than 10 degrees, the first MOF transmits more than 50% of the light at blue wavelengths and reflects more than 60% of the green and red peak wavelengths. The second MOF transmits more than 50% at blue, green, and red peak wavelengths and reflects more than about 60% at UV wavelengths. At an oblique incidence angle, the first MOF reflects more than 50% at blue, green, and red peak wavelengths and the second MOF transmits more than 50% at blue, green, and red peak wavelengths and transmits more than 60% at UV wavelengths.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to optical films, and more particularly to multilayer optical film structures for backlit display systems. [Background technology]

[0002] Display systems, such as liquid crystal display (LCD) systems, are used in a variety of applications, including commercial devices such as computer monitors, personal digital assistants (PDAs), cell phones, small music players, and thin LCD televisions. Many LCDs include a liquid crystal panel and a broad-area light source, often called a backlight, for illuminating the liquid crystal panel. The backlight typically includes one or more light sources and a number of light management films, such as light guides, mirror films, light redirection films (including brightness enhancement films), retarder films, polarizing films, and diffusion films. Other materials may be included in one or more of the layers of the light management films to reduce the adverse effects of UV light. Summary of the Invention

[0003] In some aspects of the present disclosure, an optical stack is provided that includes one or more light conversion layers. The one or more light conversion layers include a green emission spectrum with at least one green peak at a corresponding green peak wavelength and a red emission spectrum with at least one red peak at a corresponding red peak wavelength. The one or more light conversion layers are configured to receive blue light that includes a blue wavelength spectrum with at least one blue peak at a corresponding blue peak wavelength and convert a portion of the received blue light into green light and red light within the respective green emission spectrum and red emission spectrum. The first optical film is disposed on the one or more light conversion layers and is substantially coextensive in length and width with the one or more light conversion layers. The first optical film includes a plurality of first layers, at least four in total. Each of the first layers has an average thickness of less than about 500 nm. For incident light incident at an incidence angle of less than about 10 degrees, the first optical film transmits more than about 50% of the incident light for the blue wavelengths and reflects more than about 60% of the incident light for each of the green peak wavelength and the red peak wavelength. For incident light incident at an angle of incidence greater than about 40 degrees, the first optical film reflects greater than about 50% of the incident light for each of the peak blue, green, and red wavelengths.

[0004] In some other aspects of the present disclosure, a display system is provided. The display system includes at least one light source configured to emit blue light including a blue wavelength spectrum with at least one blue peak at a corresponding blue peak wavelength, and emit ultraviolet (uv) light with a uv wavelength less than the blue peak wavelength. The display panel is arranged to receive light from the at least one light source to form an image. The first optical film is arranged between the display panel and the second optical film. The display system includes one or more light conversion layers including a green emission spectrum with at least one green peak at a corresponding green peak wavelength, and a red emission spectrum with at least one red peak at a corresponding red peak wavelength. The one or more light conversion layers are configured to receive the emitted blue light and convert a portion of the received blue light into green light and red light within the respective green emission spectrum and red emission spectrum. For incident light incident at an angle of incidence less than about 10 degrees, the first optical film transmits greater than about 50% of the incident light for blue wavelengths and reflects greater than about 60% of the incident light for each of the green and red peak wavelengths, and the second optical film transmits greater than about 50% of the incident light for each of the blue, green and red peak wavelengths and reflects greater than about 60% of the incident light for uv wavelengths. For incident light incident at an angle of incidence greater than about 40 degrees, the first optical film reflects greater than about 50% of the incident light for each of the blue, green and red peak wavelengths, and the second optical film transmits greater than about 50% of the incident light for each of the blue, green and red peak wavelengths and transmits greater than about 60% of the incident light for uv wavelengths.

[0005] In some aspects of the present disclosure, a display system is provided that includes a display panel disposed on an optical stack of one or more embodiments of the present disclosure and configured to form an image.

[0006] These and other aspects will become apparent from the following detailed description, but in no way should this brief summary be construed as limiting the claimed subject matter. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a display system including various light management films. [Diagram 2] 1 shows the emission spectrum of blue light emitted by a light emitting source, the emission spectrum of a light conversion film, and the transmittance versus wavelength of an optical film at different angles of incidence according to some embodiments. [Diagram 3] 1 is a schematic cross-sectional view of a multilayer optical construction of optical films within an optical stack according to some embodiments. [Figure 4] 1 is a schematic cross-sectional view of an optical stack according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the specification. Accordingly, the following detailed description is not to be taken in a limiting sense.

[0009] In recent years, there has been an explosion in the number and variety of display devices. Computers (whether desktop, laptop, or notebook), personal digital assistants (PDAs), cell phones, and thin LCD TVs are just a few examples. Some of these devices can use normal ambient light to view the display, but most include a light panel called a backlight to make the display visible. In many applications, liquid crystal displays (LCDs) require a backlight unit as an illuminator that is efficient and spatially, angularly, and spectrally uniform.

[0010] Many such backlights fall into the categories of "edge-lit" or "direct-lit". These categories differ in the placement of the light sources relative to the output area of ​​the backlight, which defines the viewable area of ​​the display device. In edge-lit backlights (1-D), the light sources are placed along the outer edge of the backlight structure, outside of the zone corresponding to the output area. The light sources typically have length and width dimensions on the order of the output area, and emit light into a light guide from which the light is extracted to illuminate the output area. In direct-lit backlights, an array of light sources (2-D) is placed directly behind the output area, and a diffuser is placed in front of the light sources to provide a more uniform light output. Backlights generally require optical films over the light sources to achieve uniformity and brightness specifications. Some direct-lit backlights also incorporate edge-mounted lights, and thus are capable of both direct-lit and edge-lit operation. Direct-lit backlights are an effective means of providing a wide range of brightness for independent areas of the display, called high dynamic range (HDR), improving the visual experience of the user.

[0011] The present disclosure describes a direct type backlight unit having an optical stack configuration with UV reflective properties for the purpose of reducing eye strain and improving the life performance of other optical film layers within the optical stack.

[0012] FIG. 1 is a schematic cross-sectional view of an illustrative display system (200) according to some embodiments. The display system (200) includes a display panel (70) illuminated from behind by a backlight system. The display system (200) is shown in the context of a Cartesian xyz coordinate system, with the z-axis corresponding substantially to a surface perpendicular to the display panel (70) and the backlight. The display panel (70) may, in some aspects, include a liquid crystal display (LCD) panel. An LCD panel may have a large number of electronically addressable picture elements (pixels) to allow for electronically addressable images. However, in some embodiments, the display panel (70) may be of a simpler design and may not include an LCD panel. For example, the display panel may be or include a light-transmitting film or other substrate on which a static image is printed.

[0013] The backlight system includes at least one light source (80) configured to emit blue light (81b) and ultraviolet (UV) light (81u). The display panel (70) can be arranged to receive light from the at least one light source (80) to form an image (71). In some embodiments, the backlight system can include multiple light emitting sources (80) configured to emit blue light (81b) and UV light (81u). The emitted blue light (81b) can have a blue wavelength spectrum (11b) including at least one blue peak (12b) at a corresponding blue peak wavelength (13b), as shown in FIG. 2. The UV light (81u) can have a UV wavelength (13u) within the UV wavelength range (50), as shown in FIG. 2. The UV wavelength (13u) can be less than the blue peak wavelength (13b). The multiple light emitting sources (80) can include a 2-D array of individual spaced apart light emitting sources formed by arranging the light emitting sources (80) in a square pattern or any desired regular pattern. In some embodiments, several light emitting sources are arranged to form zones, and the zones are arranged in a regular pattern. The actual number of light emitting sources (80) required depends on the size of the display panel (70), the luminous flux of each light emitting source (80), and the desired brightness. In some embodiments, one or more of the light emitting sources (80) may include a plurality of individual light emitting diodes (LEDs). The LEDs forming the 2-D array of individual light emitting sources are in electrical communication such that the LEDs can be operated in a series or parallel fashion, or a combination of series and parallel as desired.

[0014] In some embodiments, one or more individual spaced apart light emission sources (80) may be disposed on a common substrate (83). In some embodiments, the common substrate (83) may be a circuit board having a plurality of conductive traces connected to the light emission sources (80) for exciting and controlling the light emission of the light emission sources (80). In the regions (84) between the one or more light emission sources (80), the common substrate (83) may have an optical reflectance, at least for the emission wavelength, of greater than about 50%, or greater than about 55%, or greater than about 60%, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%, or greater than about 90%, or greater than about 95%.

[0015] In some embodiments, the display system (200) is disposed on the optical stack (100). The optical stack (100) according to one or more aspects disclosed herein includes one or more multilayer optical films (MOFs) that include regions of substantial blue transmission for light substantially perpendicular to the film plane, while also being substantially red and green reflective for other regions of the visible spectrum. The MOFs also include the ability to reflect UV or lower blue wavelength ranges, which may be emitted by a light emitting source (80), such as a blue LED element.

[0016] The structure of the optical stack (100) is further described with reference to Figures 1 to 4. The optical stack (100) may include one or more light conversion regions (10) configured to receive light from one or more light emission sources (80). The one or more light conversion regions (10) may include one or more light conversion layers (10a, 10b). The light emitted by the light emission sources (80) has a shorter wavelength than the wavelength emitted from the light conversion layers (10a, 10b). The light conversion layers (10a, 10b) may be configured to provide a more uniform distribution of emitted light and brightness uniformity than light emitted by light emission sources (80) including LEDs.

[0017] In some embodiments, the light conversion layer (10a, 10b) may include one or more light conversion materials configured to receive light having a generally first wavelength and, in response, emit a second light having one or more different second wavelengths. In some cases, the first wavelength may be less than the one or more different second wavelengths. For example, the first wavelength may be less than about 420 nm, and the one or more different second wavelengths may be greater than about 420 nm. For example, the light emission source (80) including an LED may typically emit blue light, and the light conversion layer (10a, 10b) may be configured to convert a portion of the blue light into red and green components. The one or more light conversion materials may include one or more of photoluminescent materials, fluorescent materials or dyes, phosphors such as blue / green / red phosphors, quantum dots, semiconductor-based light converters, and the like, in a matrix of a polymer, such as an epoxide, acrylic, urethane, SEBS, and the like.

[0018] According to some embodiments, such as that shown in FIG. 2, the one or more light conversion layers (10a, 10b) may include a green emission spectrum (11g) including at least one green peak (12g) at a corresponding green peak wavelength (13g) and a red emission spectrum (11r) including at least one red peak (12r) at a corresponding red peak wavelength (13r). The one or more light conversion layers (10a, 10b) are configured to receive blue light (14b) and convert at least a portion of the received blue light (14b) into green light (14g) and red light (14r) within the respective green emission spectrum (11g) and red emission spectrum (11r). In some cases, the one or more light conversion layers may include at least a first light conversion layer (10a) and a second light conversion layer (10b) including respective green emission spectrum and red emission spectrum. The first light conversion layer (10a) and the second light conversion layer (10b) may be configured to receive blue light and convert at least a portion of the received blue light (14b) into green light (14g) and red light (14r) within respective green emission spectra (11g) and red emission spectra (11r).

[0019] The optical stack (100) includes a first optical film (20) disposed on one or more light conversion layers (10a, 10b). In some embodiments, the first optical film (20) may be substantially coextensive in length (y-axis) and width (x-axis) with the one or more light conversion layers (10a, 10b).

[0020] The first optical film (20) may be configured as a multilayer optical film including a plurality of first layers (21, 22), as shown in FIG. 3. The plurality of first layers (21, 22) may include a plurality of polymer layers. The plurality of first layers (21, 22) may reflect or transmit light primarily by constructive or destructive optical interference. For example, the plurality of first layers (21, 22) may have different refractive index characteristics such that some light is reflected at interfaces between adjacent layers. The plurality of first layers (21, 22) may be sufficiently thin such that light reflected at the plurality of interfaces undergoes constructive or destructive interference to impart the first optical film (20) with desired reflective or transmissive properties.

[0021] In some cases, the multiple first layers (21, 22) may include multiple alternating first polymer A layers (21) and first polymer B layers (22). The first polymer A layers (21) may be substantially isotropic, i.e., the refractive indices along two orthogonal in-plane directions are similar.

number

[0022] In some other cases, the plurality of first layers (21, 22) may include a plurality of vapor-deposited alternating first organic layers (21) and first inorganic layers (22). For example, the first organic layer (21) may include a polymer. For example, the polymeric first layer (21) may include one or more of polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), CoPMMA with PET, glycol-modified polyethylene terephthalate (PETG), polyethylene naphthalate (PEN), PC:PETG alloy, and PEN / PET copolymer.

[0023] The first inorganic layer (22) may include one or more of an oxide, a nitride, a carbide, and a metal. The oxide may include a metal oxide, silicon oxide, silicon dioxide, zirconium oxide, and titanium oxide, or a combination thereof. The metal oxide may include, for example, an oxide of indium, tin, or an indium-tin alloy. The nitride may include, for example, silicon nitride, zirconium nitride, and titanium nitride, or a combination thereof. The carbide may include, for example, one or more of silicon carbide and germanium carbide, or a combination thereof. In some cases, the metal may include, for example, one or more of gold, silver, and aluminum, or an alloy thereof.

[0024] The number of the plurality of first layers (21, 22) may be at least 4, or at least 6, or at least 8, or at least 10, or at least 20, or at least 30, or at least 50, or at least 75, or at least 100, or at least 150, or at least 200 in total. Each of the first layers (21, 22) may have an average thickness of less than about 500 nm. In some cases, the average thickness may be less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm. In some embodiments, the first optical film (20) may further include at least one skin layer (23) having an average thickness of more than about 500 nm, or more than about 750 nm, or more than about 1000 nm, or more than about 1500 nm, or more than about 2000 nm.

[0025] In some embodiments, a first optical bonding layer (60) may bond one or more light conversion layers (10a, 10b) to the first optical film (20). The bonding layer (60) may be an optically clear adhesive. In some other embodiments, the one or more light conversion layers (10a, 10b) may be coated on a major surface (24) of the first optical film (20), as best shown in FIG.

[0026] The first optical film (20) may be configured to transmit incident light of blue wavelengths and reflect incident light of each of green and red peak wavelengths. In some embodiments, the first optical film (20) may be said to be substantially transmissive if, for incident light (30) incident at an angle of incidence (θ1) of less than about 10 degrees, or less than about 8 degrees, or less than about 6 degrees, or less than about 4 degrees, or less than about 3 degrees, or less than about 2 degrees, or less than about 1 degree, more than about 50% of the incident light (30) of blue wavelengths is transmitted (T1b) by the first optical film (20). In some other embodiments, more than 55%, or more than 60%, or more than 65%, or more than 70%, or more than 75%, or more than 80% of the incident light (30) of blue wavelengths incident at an angle of incidence (θ1) of less than about 10 degrees may be transmitted (T1b) by the first optical film (20).

[0027] In some embodiments, the first optical film (20) can be said to be substantially reflective if, for incident light (30) incident at an angle of incidence (θ1) of less than about 10 degrees, or less than about 8 degrees, or less than about 6 degrees, or less than about 4 degrees, or less than about 3 degrees, or less than about 2 degrees, or less than about 1 degree, more than about 60% of the incident light (30) for each of the green peak wavelength and the red peak wavelength is reflected (1-T1g, 1-T1r) by the first optical film (20). In some other embodiments, more than about 65%, or more than 70%, or more than 80%, or more than 85%, or more than 90%, or more than 95%, or more than 99% of the incident light (30) for each of the green peak wavelength and the red peak wavelength incident at an angle of incidence (θ1) of less than about 10 degrees may be reflected (1-T1g, 1-T1r) by the first optical film (20).

[0028] In some embodiments, the first optical film (20) can be said to be substantially reflective if, for incident light (31) incident at an angle of incidence (θ2) of greater than about 40 degrees, or greater than about 45 degrees, or greater than about 50 degrees, or greater than about 55 degrees, greater than 50% of the incident light for each of the blue, green, and red peak wavelengths is reflected (1-T1') by the first optical film (20). In some other embodiments, greater than 55%, or greater than 60%, or greater than 65%, or greater than 70%, or greater than 75%, or greater than 80%, or greater than 85%, or greater than 90%, or greater than 95% of the incident light (31) for each of the blue, green, and red peak wavelengths incident at an angle of incidence (θ2) of greater than about 40 degrees may be reflected (1-T1') by the first optical film (20).

[0029] In one embodiment, the optical stack (100) may further include a second optical film (40) disposed on the one or more light conversion layers (10a, 10b) and the first optical film (20). In some aspects, the second optical film (40) may be substantially coextensive in length and width with the one or more light conversion layers (10a, 10b) and the first optical film (20). In the exemplary embodiment shown in FIG. 1, the first optical film (20) is disposed between the second optical film (40) and the one or more light conversion layers (10a, 10b). In other aspects, the first optical film (20) may be disposed between the display panel (70) and the second optical film (40).

[0030] In some embodiments, a second optical bonding layer (61) may be provided to bond the second optical film (40) to the first optical film (20). The bonding layer (61) may be an optically clear adhesive.

[0031] The second optical film (40) may also be configured as a UV-cut multilayer optical film including a plurality of second layers (21, 22), as shown in FIG. 3. The plurality of second layers (21, 22) may include a plurality of polymer layers. The plurality of second layers (21, 22) may reflect or transmit light primarily by constructive or destructive optical interference. For example, the plurality of second layers (21, 22) may have different refractive index characteristics such that some light is reflected at interfaces between adjacent layers. The plurality of second layers (21, 22) may be sufficiently thin such that light reflected at the plurality of interfaces undergoes constructive or destructive interference to impart the second optical film (40) with desired reflective or transmissive properties.

[0032] In some cases, the plurality of second layers (21, 22) may include a plurality of alternating second polymer A layers (21) and second polymer B layers (22). The second polymer A layers (21) may be substantially isotropic, i.e., the refractive indices along two orthogonal in-plane directions are similar.

number

[0033] In some other cases, the plurality of second layers (21, 22) may include a plurality of vapor-deposited alternating second organic layers (21) and second inorganic layers (22). For example, the second organic layer (21) may include a polymer, in some cases a cross-linked polymer. For example, the second polymer layer (21) may include one or more of polycarbonate, polymethylmethacrylate (PMMA), an acrylic polymer or copolymer, polyethylene terephthalate (PET), glycol-modified polyethylene terephthalate (PETG), a substantially amorphous copolymer of PET, polyethylene naphthalate (PEN), a PC:CoPET alloy, and a PEN / PET copolymer.

[0034] The second inorganic layer (22) may include one or more of an oxide, a nitride, a carbide, and a metal. The oxide may include a metal oxide, silicon oxide, silicon dioxide, zirconium oxide, and titanium oxide, or a combination thereof. The metal oxide may include, for example, an oxide of indium, tin, or an indium-tin alloy. The nitride may include, for example, silicon nitride, zirconium nitride, and titanium nitride, or a combination thereof. The carbide may include, for example, one or more of silicon carbide and germanium carbide, or a combination thereof. In some cases, the metal may include, for example, one or more of gold, silver, and aluminum, or an alloy thereof.

[0035] The number of the plurality of second layers (21, 22) may be at least 4, or at least 6, or at least 8, or at least 10, or at least 20, or at least 30, or at least 50, or at least 75, or at least 100, or at least 150, or at least 200 in total. Each of the second layers (21, 22) may have an average thickness of less than about 500 nm. In some cases, the average thickness may be less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm. In some embodiments, the second optical film (40) may further include at least one skin layer (23) having an average thickness of more than about 500 nm, or more than about 750 nm, or more than about 1000 nm, or more than about 1500 nm, or more than about 2000 nm.

[0036] At an incident angle (θ1) of less than about 10 degrees, the second optical film (40) may be configured to substantially transmit incident light (30) at each of the blue peak wavelengths (12b), the green peak wavelengths (12g), and the red peak wavelengths (12r).

[0037] 2 and 3, for incident light (30) incident at an angle of incidence (θ1) of less than about 10 degrees, or less than about 8 degrees, or less than about 6 degrees, or less than about 4 degrees, or less than about 3 degrees, or less than about 2 degrees, or less than about 1 degree, the second optical film (40) may be configured to transmit (T2b, T2g, T2r) more than about 50% of the incident light for each of the blue peak wavelength (12b), green peak wavelength (12g), and red peak wavelength (12r). In some cases, more than 55%, or more than 60%, or more than 65%, or more than 70%, or more than 75%, or more than 80%, and in some cases more than 85%, of the incident light (30) incident at an angle of incidence (θ1) of 0 to 10 degrees for each of the blue peak wavelength (12b), green peak wavelength (12g), and red peak wavelength (12r) may be transmitted by the second optical film (40).

[0038] In some embodiments, the second optical film (40) may be configured to substantially reflect incident light for a UV wavelength range (50) having only wavelengths less than the blue peak wavelength, and may be at least 10 nm, or 15 nm, or 20 nm, or 25 nm, or 30 nm, or 35 nm, or 40 nm wide.

[0039] In some examples, the second optical film (40) may comprise an average light reflectance of greater than 60% of incident light (30) incident at an angle of incidence (θ1) of less than about 10 degrees, or less than about 8 degrees, or less than about 6 degrees, or less than about 4 degrees, or less than about 3 degrees, or less than about 2 degrees, or less than about 1 degree for the UV wavelength range (50). In some cases, greater than 65%, or greater than 70%, or greater than 80%, or greater than 85%, or greater than 90%, or greater than 95% of incident light (30) incident at an angle of incidence (θ1) of 0-10 degrees for the uv wavelength range may be reflected by the second optical film (40).

[0040] In other aspects, the second optical film (40) may be configured to substantially transmit incident light (30) incident at an angle of incidence (θ2) of greater than about 40 degrees. In some examples, the second optical film (40) may transmit greater than about 50%, or greater than about 55%, or greater than about 60%, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%, or greater than about 90%, or greater than about 95%, or greater than about 98% of the incident light at an angle of incidence (θ2) of greater than about 40 degrees, or greater than about 45 degrees, or greater than about 50 degrees, or greater than about 55 degrees for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength.

[0041] In other examples, the second optical film (40) may have high transmission for the UV wavelength range (50) at oblique incidence. For example, as shown in Figure 2, the second optical film (40) may have an average light transmission of greater than about 60%, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%, or greater than about 90%, or greater than about 95%, or greater than about 95% of incident light for the UV wavelength range (50) at an angle of incidence (θ2) of greater than about 40 degrees, or greater than about 45 degrees, or greater than about 50 degrees, or greater than about 55 degrees.

[0042] In some embodiments, as shown in FIG. 1, one or more barrier layers (110) may be disposed on one or more light conversion layers (10a, 10b). The barrier layer (110) may have low oxygen permeability and / or water vapor permeability. The barrier layer (110) substantially supports and protects the one or more light conversion layers (10a, 10b) by substantially preventing moisture or gas from penetrating the light conversion layers (10a, 10b). In some cases, the one or more light conversion layers (10a, 10b) may be disposed between two barrier layers.

[0043] The barrier layer (110) may be of sufficient thickness and may be composed of an inorganic or polymeric material that is transparent to light and has a high barrier against moisture and / or oxygen. For example, the barrier layer (110) may be composed of SiCN or SiO2 or SiOx, an acrylate-based polymer or copolymer, or one or more of polyethylene, polypropylene, polyvinyl chloride, polyvinyl alcohol, ethylene vinyl alcohol, polychlorinated triple fluoroethylene, polyvinylidene chloride, nylon, polyaminoether, and cycloolefin-based homopolymers or copolymers.

[0044] In some embodiments, a light diffuser (90) may be disposed between the display panel (70) and the light emission source (80). In some embodiments, as shown in Figure 1, a diffuser film (90) may be disposed between the optical stack (100) and the light emission source (80).

[0045] The light diffuser (90) may include a surface diffuser, a bulk diffuser, and / or an embedded diffuser. The diffuser according to some embodiments of the present disclosure may be a separate layer or coating with diffusing properties for visible light, or a surface treatment (e.g., a surface diffuser) on a layer of the optical structure of the present disclosure that imparts diffusing properties to the treated surface. For example, the diffusing element may be a separate layer (e.g., a bulk diffuser) that diffuses visible light and is coextruded with, coated on, or laminated to another layer of the optical structure of the present disclosure. The light diffuser (90) may further facilitate light diffusion and recycling. In some cases, the light diffuser (90) may be comprised of embedded particles that scatter light, or may utilize surface structures, or both, to further improve spatial uniformity and tailor the angular distribution of the top film to maximize efficiency.

[0046] The light diffuser (90) may have a total light transmittance of greater than about 50%, or greater than about 55%, or greater than about 60%, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80% for each of the blue peak wavelengths (12b), green peak wavelengths (12g), and red peak wavelengths (12r). For at least the blue peak wavelength (12b), the light diffuser (90) may have a greater diffuse light transmittance Td and a smaller positive optical transmittance Ts. In some cases, Td>Ts and is at least 10%, or 20%, or 30%. In other cases, the light diffuser (90) may have a greater diffuse light transmittance Td1 and a smaller positive optical transmittance Ts1 for each of the blue peak wavelengths (12b), green peak wavelengths (12g), and red peak wavelengths (12r). In some cases, Td1>Ts1 by at least 10%, or 20%, or 30%.

[0047] The light diffuser (90) may have an average total light transmittance of greater than about 60%, or greater than about 65%, or greater than about 70%, or greater than about 80% for the UV wavelength range (50). In some cases, the light diffuser (90) may have a greater total light reflectance and a lesser total light transmittance for the UV wavelength range (50). In some cases, the total light reflectance of the light diffuser (90) may be at least 10%, or 20%, or 30% greater than the total light transmittance for the UV wavelength range (50).

[0048] One or more brightness enhancing films, such as prism films (120, 130), may be disposed between the display panel (70) and the optical stack (100). A first prism film (120) may be disposed between the display panel (70) and the light conversion layers (10a, 10b), and a second prism film (130) may be disposed between the display panel (70) and the first prism film (120). The prism films (120, 130) are typically optically transparent. The prism films (120, 130) may be configured to transmit light with an angular distribution to enhance axial illumination while recycling a portion to improve uniformity and brightness. The prism films (120, 130) may also split the incident image to further improve uniformity. Exemplary prism films useful for increasing the brightness of a display panel are provided by 3M Company as Vikuiti™ Brightness Enhancement Films (BEF).

[0049] In some embodiments, the first prism film (120) may include a plurality of first prisms (121) extending along substantially the same first longitudinal direction (y-axis), and the second prism film (130) may include a plurality of second prisms (131) extending along substantially the same second longitudinal direction (x-axis) that is different from the first longitudinal direction (y-axis).

[0050] In some embodiments, a reflective polarizer (140) may be disposed between the display panel (70) and the optical stack (100). The reflective polarizer (140) transmits a polarization state parallel to the transmission axis of the bottom polarizer of the display panel (70) and can recycle the orthogonal polarization to improve brightness and uniformity.

[0051] The reflective polarizer (140) may also be configured as a multilayer optical film including multiple third layers (21, 22) as shown in FIG. 3, similar to the first and / or second optical films (20, 40). The multiple third layers (21, 22) may include multiple polymer layers. The multiple third layers (21, 22) may reflect or transmit light primarily by constructive or destructive optical interference. For example, the multiple third layers (21, 22) may have different refractive index characteristics such that some light is reflected at interfaces between adjacent layers. The multiple third layers (21, 22) may be sufficiently thin so that the light reflected at the multiple interfaces undergoes constructive or destructive interference to impart the desired reflective or transmissive properties to the reflective polarizer (140).

[0052] The number of the plurality of third layers (21, 22) may be at least 10, or at least 20, or at least 30, or at least 50, or at least 75, or at least 100, or at least 150, or at least 200, or at least 250, or at least 300, or at least 350, or at least 400 in total. Each of the third layers (21, 22) may have an average thickness of less than about 500 nm. In some cases, the average thickness may be less than about 400 nm, or less than about 350 nm, or less than about 300 nm, or less than about 250 nm, or less than about 200 nm. In some embodiments, the reflective polarizer (140) may further include at least one skin layer (23) having an average thickness of more than about 500 nm, or more than about 750 nm, or more than about 1000 nm, or more than about 1500 nm, or more than about 2000 nm.

[0053] In some aspects, for substantially perpendicular incident light (30) and for each of the blue peak wavelength (12b), green peak wavelength (12g), and red peak wavelength (12r), the reflective polarizer (140) including the plurality of third polymer layers (21, 22) may reflect more than 60% of the incident light having an in-plane first polarization state (x-axis). In some embodiments, for substantially perpendicular incident light (30) and for each of the blue peak wavelength (12b), green peak wavelength (12g), and red peak wavelength (12r), the reflective polarizer (140) including the plurality of third polymer layers (21, 22) may reflect more than about 70%, or at least 80%, or at least 90%, or at least 95% of the incident light having an in-plane first polarization state (x-axis).

[0054] For substantially perpendicular incident light (30) and for each of the blue peak wavelength (12b), green peak wavelength (12g), and red peak wavelength (12r), the reflective polarizer (140) including the plurality of third polymer layers (21, 22) may transmit greater than about 60% of the incident light having an orthogonal in-plane second polarization state (y-axis). In some embodiments, for substantially perpendicular incident light (30) and for each of the blue peak wavelength (12b), green peak wavelength (12g), and red peak wavelength (12r), the reflective polarizer (140) including the plurality of third polymer layers (21, 22) may transmit at least 70%, or at least 80%, or at least 90%, or at least 95% of the incident light having an orthogonal in-plane second polarization state (y-axis).

[0055] Descriptions of elements in the drawings should be understood to apply equally to corresponding elements in other drawings unless otherwise indicated. Although specific embodiments have been illustrated and described herein, those skilled in the art will appreciate that the specific embodiments illustrated and described may be replaced by various alternative and / or equivalent implementations without departing from the scope of the present disclosure. The present application is intended to cover any adaptations, or variations, or combinations of the specific embodiments discussed herein. Accordingly, the present disclosure is intended to be limited only by the claims and the equivalents thereof.

Claims

1. An optical laminate, one or more light conversion layers including a green emission spectrum including at least one green peak at a corresponding green peak wavelength and a red emission spectrum including at least one red peak at a corresponding red peak wavelength, the one or more light conversion layers configured to receive blue light including a blue wavelength spectrum including at least one blue peak at a corresponding blue peak wavelength and to convert a portion of the received blue light into green light and red light within the green emission spectrum and the red emission spectrum, respectively; a first optical film disposed on the one or more light conversion layers and substantially coextensive in length and width with the one or more light conversion layers, the first optical film including a plurality of first layers totaling at least four, each of the first layers having an average thickness of less than about 500 nm; for incident light incident at an angle of incidence of less than about 10 degrees, the first optical film transmits greater than about 50% of the incident light at the blue wavelengths and reflects greater than about 60% of the incident light at each of the green peak wavelength and the red peak wavelength; an optical stack, wherein for incident light incident at an angle of incidence greater than about 40 degrees, the first optical film reflects greater than about 50% of the incident light for each of the peak blue wavelength, the peak green wavelength, and the peak red wavelength.

2. 10. The optical stack of claim 1, wherein the plurality of first layers comprises a plurality of alternating first organic and first inorganic layers, the first organic layers comprising a polymer, and the first inorganic layers comprising one or more of an oxide, a nitride, a carbide, and a metal.

3. a second optical film disposed on the one or more light conversion layers and the first optical film and substantially coextensive in length and width with the one or more light conversion layers and the first optical film, the second optical film comprising a plurality of second layers totaling at least four, each of the second layers having an average thickness of less than about 500 nm; and for an ultraviolet (uv) wavelength range that includes only wavelengths less than the blue peak wavelength and is at least 10 nm wide: for incident light incident at an angle of incidence of less than about 10 degrees, the second optical film transmits greater than about 50% of the incident light for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, and has an average light reflectance of greater than about 60% for the uv wavelength range; 2. The optical stack of claim 1, wherein for incident light incident at an angle of incidence greater than about 40 degrees, the second optical film transmits greater than about 50% of the incident light for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, and has an average light transmittance of greater than about 60% for the UV wavelength range.

4. A display system comprising a display panel disposed on the optical stack of claim 3 and configured to form an image.

5. 5. The display system of claim 4, further comprising a plurality of individual, spaced apart light sources configured to emit blue light comprising the blue wavelength spectrum, wherein at least one of the light sources in the plurality of light sources is further configured to emit UV light having a UV wavelength within the UV wavelength range.

6. The display system of claim 5, further comprising a light diffuser disposed between the optical stack and the light source, the light diffuser having a total light transmittance of greater than about 50% for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, and having an average total light transmittance of greater than about 60% for the UV wavelength range.

7. 6. The display system of claim 5, wherein the light diffuser has a greater diffuse light transmittance and a lesser specular light transmittance for at least the blue peak wavelength, and a greater total light reflectance and a lesser total light transmittance for the UV wavelength range.

8. 5. The display system of claim 4, further comprising: a reflective polarizer disposed between the display panel and the optical stack, the reflective polarizer comprising a plurality of third polymer layers totaling at least 10, each of the third polymer layers having an average thickness less than about 500 nm, and for substantially normally incident light and each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, the plurality of third polymer layers reflects more than about 60% of the incident light having an in-plane first polarization state and transmits more than about 60% of the incident light having an in-plane orthogonal second polarization state.

9. 2. The optical stack of claim 1, wherein the one or more light conversion layers include at least a first light conversion layer and a second light conversion layer that include the green emission spectrum and the red emission spectrum, respectively, and the first light conversion layer and the second light conversion layer are configured to receive the blue light and convert a portion of the received blue light into the green light and the red light within the green emission spectrum and the red emission spectrum, respectively.

10. 1. A display system comprising: at least one light source configured to emit blue light having a blue wavelength spectrum including at least one blue peak at a corresponding blue peak wavelength, and to emit ultraviolet (UV) light having a UV wavelength less than the blue peak wavelength; a display panel positioned to receive light from the at least one light source and form an image; a first optical film disposed between the display panel and a second optical film; one or more light conversion layers including a green emission spectrum comprising at least one green peak at a corresponding green peak wavelength and a red emission spectrum comprising at least one red peak at a corresponding red peak wavelength, the one or more light conversion layers configured to receive the emitted blue light and convert a portion of the received blue light into green light and red light within the green emission spectrum and the red emission spectrum, respectively; For incident light incident at an angle of incidence of less than about 10 degrees, the first optical film transmits more than about 50% of the incident light for the blue wavelength and reflects more than about 60% of the incident light for each of the green peak wavelength and the red peak wavelength; and the second optical film transmits more than about 50% of the incident light for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength and reflects more than about 60% of the incident light for the uv wavelength range; A display system, wherein for incident light incident at an angle of incidence greater than about 40 degrees, the first optical film reflects greater than about 50% of the incident light for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, and the second optical film transmits greater than about 50% of the incident light for each of the blue peak wavelength, the green peak wavelength, and the red peak wavelength, and transmits greater than about 60% of the incident light for the UV wavelengths.

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