Polarizer and display including polarizer

Abstract

The present invention describes a display (1000) comprising a display panel (130) and a polarizer (110) arranged to receive a light (150) output of the display panel (130). The polarizer (150) may be a reflective polarizer (110) or a circular polarizer (100) incorporating the reflective polarizer (110). The display panel (130) comprises a plurality of pixels, and each pixel comprises a plurality of sub-pixels. The reflective polarizer (110) has a first reflection band, wherein at normal incidence, the first reflection band has a long wavelength band edge wavelength between peak emission wavelengths of two sub-pixels in the plurality of sub-pixels. The reflective polarizer (110) may be arranged in the circular polarizer (100) between an absorptive polarizer (106) and a retarder (108). The reflective polarizer (110) may have substantially non-overlapping first, second, and third reflection bands.

Description

Background Art

[0001] Organic light emitting diode displays often include circular polarizers to reduce reflection of ambient light from the display panel. Summary of the invention

[0002] In some aspects of the specification, a display is provided, the display comprising a display panel and a reflective polarizer, the reflective polarizer being arranged to receive a light output of the display panel. The display panel comprises a plurality of pixels, wherein each pixel comprises a plurality of sub-pixels. The reflective polarizer has a first reflection band. Under normal incidence, the first reflection band has a long wavelength band edge wavelength between peak emission wavelengths of two sub-pixels in the plurality of sub-pixels.

[0003] In some aspects of the specification, a circular polarizer is provided, the circular polarizer comprising a retarder, an absorbing polarizer, and a reflective polarizer disposed between the retarder and the absorbing polarizer. The reflective polarizer has a transmission axis substantially aligned with the transmission axis of the absorbing polarizer. The reflective polarizer comprises a plurality of alternating polymer interference layers and has a substantially non-overlapping first reflection band, a second reflection band, and a third reflection band. Under normal incidence: the first reflection band has a short wavelength band edge wavelength and a long wavelength band edge wavelength, the second reflection band has a long wavelength band edge wavelength in the range of 440nm to 500nm, and the third reflection band has a short wavelength band edge wavelength in the range of 580nm to 640nm. The short wavelength band edge wavelength of the first reflection band is at least 10nm greater than the long wavelength band edge wavelength of the second reflection band. The short wavelength band edge wavelength of the third reflection band is at least 10nm greater than the long wavelength band edge wavelength of the first reflection band.

[0004] In some aspects of the present specification, a reflective polarizer is provided, the reflective polarizer comprising a plurality of alternating polymer interference layers. The plurality of alternating polymer interference layers have substantially non-overlapping first, second and third reflection bands. Each of the first, second and third reflection bands is a first-order harmonic reflection band. The plurality of alternating polymer interference layers include an outermost first interference layer and a second interference layer, and each layer disposed between the outermost first and second interference layers in the reflective polarizer has a thickness of less than 1 micron. Under normal incidence: the first reflection band has a short wavelength band edge wavelength and a long wavelength band edge wavelength, the second reflection band has a long wavelength band edge wavelength in the range of 440nm to 500nm, and the third reflection band has a short wavelength band edge wavelength in the range of 580nm to 640nm. The short wavelength band edge wavelength of the first reflection band is at least 10nm greater than the long wavelength band edge wavelength of the second reflection band. The short wavelength band edge wavelength of the third reflection band is at least 10nm greater than the long wavelength band edge wavelength of the first reflection band.

[0005] In some aspects of the specification, a display is provided, the display comprising a display panel and a reflective polarizer, the reflective polarizer being configured to receive light output from the display panel. The display panel comprises a plurality of pixels, wherein each pixel comprises a plurality of sub-pixels. The reflective polarizer has a first reflection band. At normal incidence, the first reflection band reflects at least 60% of a first light having a blocking polarization state and a wavelength distribution of an emission spectrum of a first sub-pixel in the plurality of sub-pixels. At an incident angle of 45 degrees, the first reflection band transmits at least 60% of the first light.

[0006] In some aspects of the specification, a circular polarizer is provided, the circular polarizer comprising a retarder and an absorbing polarizer and a reflective polarizer disposed between the retarder and the absorbing polarizer. The absorbing polarizer has an absorption band extending throughout the visible range of 400 nm to 700 nm. The reflective polarizer has a transmission axis substantially aligned with the transmission axis of the absorbing polarizer. The reflective polarizer comprises a plurality of alternating polymer interference layers and has a reflection band and at least one transmission band in a block polarization state. At normal incidence, the at least one transmission band has a total width of at least 150 nm in the visible range.

[0007] In some aspects of the specification, a reflective polarizer is provided, the reflective polarizer having at least one reflection band with a bandwidth less than 150 nm. In some embodiments, the circular polarizer includes a reflective polarizer disposed between an absorbing polarizer and a retarder. In some embodiments, a display includes a display panel and a circular polarizer, the circular polarizer being configured to receive the light output of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic cross-sectional view of a display including a display panel and a reflective polarizer;

[0009] Figure 2 is a schematic top view of a display panel including a plurality of pixels;

[0010] Figure 3 is a schematic depiction of the emission spectrum of a sub-pixel;

[0011] Figure 4A is a schematic depiction of substantially non-overlapping first, second, and third reflection bands of a reflective polarizer and emission spectra of a first subpixel, a second subpixel, and a third subpixel at normal incidence;

[0012] Figure 4B is a schematic depiction of substantially non-overlapping first, second, and third reflection bands of a reflective polarizer and emission spectra of a first subpixel, a second subpixel, and a third subpixel at off-normal incidence;

[0013] Figures 5 and 6 is a schematic graph of reflectivity of a reflective polarizer for light having a block polarization state as a function of wavelength at a fixed angle of incidence;

[0014] Figures 7 and 8 is a schematic graph of reflectivity of a reflective polarizer as a function of wavelength at a fixed angle of incidence for light having a block polarization state, the reflective polarizer having two reflection bands in the depicted wavelength range for the light;

[0015] Figures 9 and 10 is a schematic graph of reflectivity of a reflective polarizer as a function of wavelength at a fixed angle of incidence for light having a block polarization state, the reflective polarizer having three reflection bands in the depicted wavelength range of the light;

[0016] Fig.11 is a schematic diagram of the transmission spectrum of a reflective polarizer;

[0017] Fig.12 is a schematic perspective view of an exemplary optical repeating unit (ORU) of a multilayer optical film;

[0018] Fig.13 is a schematic side view of a multilayer optical film;

[0019] Figures 14 to 17 is a schematic graph of layer thickness distribution in a reflective polarizer;

[0020] Fig.18 is a schematic cross-sectional view of a reflective polarizer;

[0021] Figure 19 to Figure 20 is a schematic cross-sectional view of a circular polarizer;

[0022] Fig.21 is a schematic depiction of the transmission axis of a reflective polarizer, the transmission axis of a linear absorptive polarizer, and the fast axis of a retarder;

[0023] Fig. 22 is a plot of unit cell thickness versus number of unit cells in a reflective polarizer;

[0024] Fig.23 is a graph of a reflective spectrum of a reflective polarizer and an emission spectrum of a sub-pixel of a display panel;

[0025] FIG. 24A to FIG. 24D are graphs of photopic gain versus aerial viewing angle for red, green, blue, and white sub-pixels, respectively;

[0026] Fig.25 is a schematic top view of a portion of a display panel;

[0027] Fig.26 is a graph of internal incident angle versus external aerial viewing angle as a function of separation distance between a reflective region and a color filter in a reflective polarizer;

[0028] Fig. 27 is a schematic representation of the walk-off distance contours in the incidence angle against the separation distance curve;

[0029] Figures 28 to 30 is the layer thickness profile of the alternating interference layers of an exemplary reflective polarizer film;

[0030] Fig.31 are the measured spectra of the block and transmit states of the reflective polarizer;

[0031] Fig.32 is the measured spectrum of the light-blocking state of the reflective polarizer and the OLED emission peak;

[0032] Fig.33 are measured spectra for block and pass states of an exemplary reflective polarizer;

[0033] Fig.34 is the measured spectrum of the block and transmit states of an exemplary reflective polarizer film and the OLED emission peak

[0034] FIG. 35A to FIG. 35E are illustrative images of pixels of a comparative display and corresponding ghost images;

[0035] FIG. 36A to FIG. 36E They are respectively from FIG. 35A to FIG. 35E Luminance distribution extracted from the image;

[0036] FIG. 37A to FIG. 37E is an image of a pixel of a display including an exemplary reflective polarizer and a corresponding ghost image;

[0037] FIG. 38A to FIG. 38E They are respectively from Figures 37A to 37E Luminance distribution extracted from the image;

[0038] Fig.39A are illustrative images of pixels of a display including an exemplary reflective polarizer at a viewing angle of 20 degrees and corresponding ghost pixels;

[0039] Fig.39B is from Fig.39A Luminance distribution extracted from the image;

[0040] Fig.40A are illustrative images of pixels of a display including an exemplary reflective polarizer at a viewing angle of 40 degrees and corresponding ghost pixels;

[0041] Fig.40B is from Fig.40A Luminance distribution extracted from the image;

[0042] Fig.41A are illustrative images of pixels and corresponding ghost pixels of a display including another exemplary reflective polarizer at a viewing angle of 20 degrees;

[0043] Fig.41B is from Fig.41A Luminance distribution extracted from the image;

[0044] Fig.42A are illustrative images of pixels and corresponding ghost pixels of a display including another exemplary reflective polarizer at a viewing angle of 40 degrees;

[0045] Fig.42B is from Fig.41A Luminance distribution extracted from the image;

[0046] Fig.43 is a plot of normalized luminance gain versus polar angle; and

[0047] Fig.44 is a plot of normalized luminance gain versus polar angle. DETAILED DESCRIPTION

[0048] In the following description, reference is made to the accompanying drawings, which form a part of this description and in which various embodiments are shown by way of illustration. The drawings are not necessarily drawn to scale. It should be understood that other embodiments may be conceived and made without departing from the scope or essence of this specification. Therefore, the following specific embodiments should not be considered to have a limiting meaning.

[0049] According to some embodiments of the present specification, a reflective polarizer is provided, the reflective polarizer having a reflective band having a band edge in the visible spectrum. It has been found that when the reflective polarizer is arranged to receive the light output of a display panel, such a reflective polarizer can be used to improve the performance of the display. For example, the reflective polarizer can be used in a circular polarizer arranged on an organic light emitting diode (OLED) display to increase the brightness of the display and / or the color gamut of the display without causing ghosting or other image degradation. In U.S. Patent 9,773,847 (Epstein et al.), it is described that a broadband reflective polarizer is used in a circular polarizer of an OLED display to increase the brightness of the display. According to some embodiments of the present specification, it has been found that the use of a notched reflective polarizer or a reflective polarizer having at least one band edge in the visible spectrum can increase the brightness and / or color gamut of the display while producing substantially less ghosting or substantially no ghosting compared to the use of a broadband reflective polarizer, and / or a reduced reflection of ambient light compared to the use of a broadband reflective polarizer. For example, in some embodiments, including a reflective polarizer in the circular polarizer increases on-axis brightness by at least 15% compared to not including the reflective polarizer, and increases color gamut by at least 2% of NTSC (a color gamut standard established by the National Television Systems Committee), and reduces ambient reflections by at least 20% compared to including a broadband reflective polarizer in the circular polarizer (e.g., from 2.9% to 1.8%, which is approximately a 38% reduction).

[0050] The reflective polarizer is typically positioned to receive the light output of a display panel (e.g., light that is spatially modulated to provide an image). For example, a display is typically configured to provide an image to a viewer, and the reflective polarizer is typically positioned between the display panel and the viewer. The display panel may be, for example, an OLED display panel. Other display panels may also be utilized in which a reflective polarizer may be advantageously placed between the display panel and the viewer.

[0051] Figure 11 is a schematic cross-sectional view of a display 1000 including a display panel 130 and a reflective polarizer 110. As further described elsewhere herein, the display panel 130 includes a plurality of pixels, each of which includes a plurality of sub-pixels. In the illustrated embodiment, the display panel includes an emission region 131, which may be a pixel or a sub-pixel, and the display panel includes regions 133 and 135, which may be emission regions or regions between emission regions, such as a black matrix between adjacent pixels or sub-pixels. In the illustrated embodiment, a layer 134 including regions 131, 133, and 135 is disposed on layer 132. Layer 132 may be, for example, an organic light emitting diode (OLED) backplane layer. In some embodiments, layer 132 schematically represents an OLED layer that produces a white light output, and layer 134 is a color filter layer that defines sub-pixels having different colors. In other embodiments, layer 134 schematically represents, for example, an emission layer of an OLED that defines a red sub-pixel, a green sub-pixel, and a blue sub-pixel. For example, in some embodiments, region 132 includes a green emitting material, region 133 includes a blue emitting material, and region 135 includes a green emitting material. Circular polarizer 100 includes a reflective polarizer 110 disposed between an absorbing polarizer 106 and a retarder 108. Layer 140 separates the circular polarizer from layer 134. Layer 140 can be a glass layer and / or an encapsulation layer, for example, depending on the design of display panel 130. In some embodiments, layer 140 is a layer of display panel 130.

[0052] Light 150 is emitted through emissive region 131 and is incident on circular polarizer 100. A portion of light 150, after passing through retarder 108, is incident on reflective polarizer 110 in a light-transmitting state, which in some embodiments is also the light-transmitting state of absorptive polarizer 106. This portion then typically exits display 1000 after passing through cover glass (not shown) and is refracted at the interface with cover glass and air as light 152. Another portion of light 150, after passing through retarder 108, is incident on reflective polarizer 110 in its light-blocking state. If this portion has a wavelength in the reflection band of reflective polarizer 110, this portion will be reflected from circular polarizer 100 as light 154. Retarder 108 is typically a quarter-wave retarder at one or more wavelengths in the visible (400nm to 700nm) spectrum (e.g., at two wavelengths when some types of achromatic retarders are used), but other retardances (e.g., 5 / 4 of a wavelength) may be used. In some embodiments, retarder 108 includes multiple retarder layers. For example, in some embodiments, a half-wave retarder layer can be combined with a quarter-wave retarder layer to provide retarder 108. Light 154 can be substantially circularly polarized. Light 154 is reflected from region 133 as light 156 having a circular polarization state that is substantially orthogonal to the circular polarization state of light 154. Light 156 is then incident on the reflective polarizer in the transmit state and exits optical system 1000.

[0053] When light 156 is a shifted replica of light from emission region 131, the light causes a ghost image. Light 156 is shifted by a distance d relative to light 152. This distance d may be referred to as a walk-off distance. In some display designs, region 133 is located between emission regions, and light 156 may be reduced by using a black matrix material in region 133 to reduce the reflectivity of the region. However, in some embodiments, region 133 is an emission region. For example, in some OLED designs, the sub-pixels in a pixel are closely or directly adjacent to each other, and regions 131 and 133 may be adjacent sub-pixels within a pixel. In this case, it will not be necessary to set the black matrix material in region 133. In embodiments where different emission OLED materials are used to define different sub-pixels, each emission region typically has a large amount of reflection of light from each other emission region. In embodiments, where color filters are used to define sub-pixels, light from different primary color sub-pixels typically has low reflection from different primary color sub-pixels, but may have a large amount of reflection from white sub-pixels when white sub-pixels are included.

[0054] According to some aspects of the present description, it has been discovered that light 156 can be reduced or substantially eliminated by selecting a reflection band of the reflective polarizer to reflect block-state light at normal incidence, but shifted at an angle of incidence so that little off-normal light that would otherwise cause ghosting is reflected from reflective polarizer 110. For example, light 150 is incident on reflective polarizer 110 at an angle of incidence θ (normal angle). If the reflection band of reflective polarizer 110 does not include the wavelength of light 150 at an angle of incidence of θ, light 150 will not be substantially reflected by reflective polarizer 110.

[0055] In some embodiments, reflective polarizer 110 has a reflection band that has a long wavelength band edge wavelength greater than the peak emission wavelength of the green sub-pixel at normal incidence, but at off-normal incidence, the long wavelength band edge is shifted such that the long wavelength band edge wavelength is less than the peak emission wavelength of the green sub-pixel. For example, if emissive region 131 is a green sub-pixel having a peak emission wavelength λg, and if the reflective polarizer has a long wavelength band edge wavelength greater than the peak emission wavelength of the green sub-pixel at normal incidence, the long wavelength band edge is shifted such that the long wavelength band edge wavelength is less than the peak emission wavelength of the green sub-pixel. 0 >λg long wavelength band edge and has λ at incident angle θ θ <λg, then if reflective polarizer 110 is substantially transmissive for the wavelengths emitted by emission region 131 at incident angle θ, reflection of light 154 from reflective polarizer 110 will be reduced or substantially eliminated.

[0056] In some embodiments, the distance D between the reflective polarizer 110 and the plurality of pixels in layer 134 is selected so that the incident angle θ where the long wavelength band edge has been sufficiently shifted to reduce reflection of light 154 corresponds to the walk-off distance between the emission region 131 and an adjacent emission region that is capable of substantially reflecting light emitted by the emission region 131. The distance D can be understood as the shortest distance between the interference layer of the reflective polarizer 110 and the sub-pixel defining layer of the display panel 130. In the case where the OLED display panel utilizes red emission material, green emission material, and blue emission material to define sub-pixels, the sub-pixel defining layer can be an emission layer, or in the case where the OLED display panel utilizes color filters to define sub-pixels, the sub-pixel defining layer can be a color filter layer. The relationship between d, D, and θ can be established by standard trigonometric functions (e.g., tan(θ)=d / (2D)). In some embodiments, the distance D is selected so that at an internal angle of incidence θ (where λ θ <λg), the walk-off distance d corresponds to the minimum distance between the first sub-pixel and the second sub-pixel that can substantially reflect light from the first sub-pixel.

[0057] Fig. 272771, 2772, 2775, and 2776. In the region between contour lines 2771 and 2772, light from the green sub-pixel reflected from the reflective polarizer may be reflected from the nearest sub-pixel having a high reflectivity for green light. This nearest sub-pixel may be a white sub-pixel when a color filter is used to define the sub-pixel, or may be the nearest sub-pixel of any color when an emissive material emitting in a different wavelength range is used to define the sub-pixel. In the region between contour lines 2775 and 2776, light from the green sub-pixel reflected from the reflective polarizer may be reflected from the next nearest sub-pixel having a high reflectivity for green light. This next nearest sub-pixel may be a green sub-pixel in an adjacent pixel when a color filter is used to define the sub-pixel, or may be the next nearest sub-pixel of any color when an emissive stack emitting in a different wavelength range is used to define the sub-pixel. The reflection band of the reflective polarizer generally shifts to a lower wavelength when the incident angle θ increases. The ranges of θ labeled 2766, 2767, and 2768 are schematically depicted in an embodiment in which the reflective polarizer has both a green reflection band and a red reflection band. In range 2766, the green reflection band strongly reflects light from the green sub-pixel. In range 2767, the green reflection band has shifted to a lower wavelength and does not strongly reflect light from the green sub-pixel. In range 2767, the red reflection band has not yet shifted to a sufficiently low wavelength that can strongly reflect light from the green sub-pixel. In range 2768, the red reflection band has shifted to a sufficiently low wavelength that can substantially reflect light from the green sub-pixel. For higher angles of incidence, neither the green reflection band nor the red reflection band strongly reflects light from the green sub-pixel.

[0058] At distance D≤Z1, since the green and red reflection bands have shifted to lower wavelengths, the reflective polarizer does not strongly reflect light from the green sub-pixel at a walk-off distance d corresponding to the region between contour lines 2771 and 2772 or the region between contour lines 2775 and 2776. Therefore, in some embodiments, to avoid ghosting from green wavelengths due to the shifted red reflection band, it may be preferred that D is sufficiently small (e.g., less than 0.8 times the center-to-center spacing between designated sub-pixels, or less than 0.6 times the center-to-center spacing, or less than 0.4 times the center-to-center spacing) so that the red reflection band is also shifted far enough to a lower wavelength that substantially does not reflect green wavelengths at the associated walk-off distance. At distance D≈Z2, since the green reflection band has shifted to lower wavelengths and the red reflection band reflects light from the green sub-pixel in the region between contours 2772 and 2775, the reflective polarizer does not strongly reflect light from the green sub-pixel at a walk-off distance d corresponding to the region between contours 2771 and 2772 or the region between contours 2775 and 2776 where reflection from the display panel is not strong. In contrast, a broadband reflective polarizer positioned at D≈Z2 will produce ghost images from reflection in the green wavelength range. Thus, in some implementations, it may be preferred that D be in a range (e.g., 0.8 to 1.2 times the center-to-center spacing between a given sub-pixel) where the green reflection band shifts to a sufficiently low wavelength that substantially does not reflect green light at the associated walk-off distance, and where the red reflection band has not shifted to a sufficiently low wavelength that substantially reflects green light at the associated walk-off distance.

[0059] Values ​​of D between Z1 and Z2 may also be used, but this is generally less preferred when this results in a substantial portion of range 2768 being in the region between contour lines 2771 and 2772, since the red reflection band may then result in undesirable reflections. Values ​​of D substantially greater than Z2 may also be used, but are generally less preferred since this may result in undesirable reflections of light from green sub-pixels in the region between contour lines 2771 and 2772 and / or in the region between contour lines 2775 and 2776. Values ​​of D between Z1 and Z2 or values ​​of D substantially greater than Z2 or other values ​​of D may be used in embodiments where the primary goal is to increase gain and / or color gamut without increasing ambient photopic reflection to, for example, above 2%, even when the value of D may not be optimal for reducing ghosting. However, it is generally preferred to select D less than or approximately equal to Z1 (e.g., within 10%) or to select D approximately equal to Z2 (e.g., within 10%) in order to minimize ghosting.

[0060] The preferred relationship between D and pixel and / or sub-pixel geometry may depend on the type of display panel used and is further described elsewhere herein.

[0061] The incident angle θ is the internal angle of light 150 relative to normal to reflective polarizer 110. The external aerial viewing angle corresponding to the incident angle θ relative to normal to the display will be substantially greater than θ due to refraction. The incident angle θ may also be denoted as θint, and the external aerial viewing angle may be denoted as θext.

[0062] In some embodiments, to achieve the desired distance D, circular polarizer 100 is positioned adjacent to display panel 130 beneath a cover glass of display 1000. A sealant, which may be or include glass, may be disposed between circular polarizer 100 and the plurality of pixels.

[0063] In some implementations, the reflective polarizer 110 has a single reflection band having a long wavelength band edge between the peak emission wavelengths of two sub-pixels (e.g., green and red or blue and green) in the plurality of sub-pixels. The single reflection band can have a short wavelength band edge wavelength between the peak emission wavelengths of the two sub-pixels (e.g., blue and green), or can have a short wavelength band edge wavelength that is, for example, less than the peak emission wavelength of each of the sub-pixels.

[0064] OLED displays utilizing 4 subpixels are known in the art and are described, for example, in U.S. Patents 7,397,485 (Miller et al.) and 9,123,668 (Park et al.), wherein each subpixel utilizes a common emitting material that emits white light, and a color filter is overlaid on the common emitting material to define a red subpixel, a green subpixel, and a blue subpixel. White subpixels may also be utilized in such displays by leaving a portion of the common emitting material uncovered by the color filter, or by using a color filter over a portion of the common emitting material to adjust the white point of the white subpixel.

[0065] Figure 2237a, 237b, 237c, and 237d. Sub-pixels 237a, 237b, 237c, and 237d may be, for example, red sub-pixels, green sub-pixels, blue sub-pixels, and white sub-pixels. In other embodiments, fewer sub-pixels (e.g., three sub-pixels, such as a red sub-pixel, a green sub-pixel, and a blue sub-pixel) or more sub-pixels (e.g., five sub-pixels, such as a red sub-pixel, two green sub-pixels, a blue sub-pixel, and a white sub-pixel) are included.

[0066] In some embodiments, each pixel 237 includes a black matrix 239 adjacent to the plurality of sub-pixels. OLED displays incorporating black matrix layers are known in the art and described in U.S. Patents 9,543,368 (Cheng et al.), 8,710,733 (Lee et al.), and 6,936,960 (Cok).

[0067] The plurality of pixels 237 have an average spacing of P1 in a first direction (x' direction) and an average spacing of P2 in a second direction (y' direction). Unless otherwise specified, the average refers to an unweighted mean. The spacing between pixels may vary, for example, due to manufacturing variations. In some cases, any difference between the local spacing between pixels and the corresponding average spacing is negligible. In some embodiments, the distance D (reference numeral 234) between the reflective polarizer and the plurality of pixels is preferably 0.001 mm / s. Figure 1 ) is in the range of 0.1 to 1 times, 0.2 to 0.8 times, or 0.2 to 0.7 times the average pitch of the plurality of pixels 237 (e.g., P1 or P2; or the smaller of P1 and P2).

[0068] The preferred value of the distance D may depend on the type of display panel 230 used. For example, in some embodiments, the display panel 230 utilizes color filters to define at least white sub-pixels and green sub-pixels. In these embodiments, the preferred distance D may be related to the average center-to-center distance Dwg between the white sub-pixels in the pixel and the green sub-pixels in the pixel. This is because when color filters are used to define sub-pixels, the green sub-pixels typically substantially reflect from the white sub-pixels but not from the red sub-pixels and blue sub-pixels that typically absorb light emitted by the green sub-pixels. The white sub-pixels also reflect light emitted by the blue sub-pixels and the red sub-pixels, but because the human eye is most sensitive to green, in some embodiments the distance D is selected based on the distance between the green sub-pixels and the white sub-pixels. In some embodiments, D is no more than 1.2 times Dwg or no more than 1 times Dwg or no more than 0.8 times Dwg or no more than 0.6 times Dwg or no more than 0.4 times Dwg (for example, corresponding to Fig. 27 In some such embodiments, or in other embodiments, D is at least 10 microns or at least 0.05 times Dwg. In some embodiments, D is in the range of 0.8 to 1.2 times Dwg (e.g., corresponding to Fig. 27 In some embodiments, D is in the range of 0.8 to 1.2 times Dwg, or D is less than 0.6 times Dwg.

[0069] In some embodiments, color filters are not used to define the sub-pixels. For example, in some embodiments, each pixel includes a red sub-pixel including a red emitting material, a green sub-pixel including a green emitting material, and a blue sub-pixel including a blue emitting material. In some such embodiments, or in other embodiments, the preferred distance D may be related to the average center-to-center distance D1 between adjacent sub-pixels. This is because in this case, each sub-pixel substantially reflects light from adjacent sub-pixels. In some embodiments, D is no more than 1.2 times D1 or no more than 1 times D1 or no more than 0.8 times D1 or no more than 0.6 times D1 or no more than 0.4 times D1 (e.g., corresponding to Fig. 27 In some such embodiments, or in other embodiments, D is at least 10 microns or at least 0.05 times D1. In some embodiments, D is in the range of 0.8 to 1.2 times D1 (e.g., corresponding to Fig. 27 In some embodiments, D is in the range of 0.8 to 1.2 times of D1, or D is less than 0.6 times of D1.

[0070] In some embodiments, it is desirable that D is sufficiently small so that the thickness of the reflective polarizer is not negligible compared to D. In some such embodiments, or in other embodiments, it may be desirable to arrange the layers of the reflective polarizer so that the layer reflecting green wavelengths is disposed closest to the outermost major surface of the reflective polarizer disposed facing the display panel. This may provide an optimal separation distance for the green reflective layer, and a suboptimal (larger) separation distance for the red and blue reflective layers. Since green wavelengths are more heavily weighted in the photopic average, this may be preferred according to some embodiments.

[0071] Figure 3 3 is a schematic illustration of emission spectra of various sub-pixels. An emission spectrum 341 of a first sub-pixel (e.g., a green sub-pixel), an emission spectrum 343 of a second sub-pixel (e.g., a blue sub-pixel), an emission spectrum 345 of a third sub-pixel (e.g., a red sub-pixel), and an emission spectrum 342 of a fourth sub-pixel (e.g., a white sub-pixel) are illustrated. Peak emission wavelengths λg, λb, and λr of the first sub-pixel, the second sub-pixel, and the third sub-pixel having emission spectra 341, 343, and 345 are shown, respectively. The peak emission wavelength of the fourth sub-pixel having emission spectrum 342 is approximately equal to the peak emission wavelength λb of the second sub-pixel having emission spectrum 343.

[0072] FIG. 4A to FIG. 4B It is a schematic illustration of substantially non-overlapping first reflection band 451, second reflection band 453 and third reflection band 455 of a reflective polarizer and an emission spectrum 447 of a display panel having at least a first sub-pixel, a second sub-pixel and a third sub-pixel, wherein the first sub-pixel has a first peak emission wavelength λg, the second sub-pixel has a second peak emission wavelength λb less than the first peak emission wavelength λg, and the third sub-pixel has a third peak emission wavelength λr greater than the first peak emission wavelength λg. Figure 4A shows the reflectivity of the reflective polarizer at normal incidence, and Figure 4B : shows the reflectivity of the reflective polarizer at an off-normal incidence angle θ, which may be, for example, 45 degrees. Under normal incidence, the first reflection band 451 includes a first peak emission wavelength λg, the second reflection band 453 includes a second peak emission wavelength λb, and the third reflection band includes a third peak emission wavelength λr. Under normal incidence, the first reflection band 451 has a long-wavelength band-edge wavelength greater than the peak emission wavelength λg of the first subpixel; the second reflection band 453 has a long-wavelength band-edge wavelength greater than the peak emission wavelength λb of the second subpixel and less than the peak emission wavelength λg of the first subpixel; and the third reflection band 455 has a long-wavelength band-edge wavelength greater than the peak emission wavelength λr of the third subpixel and has a short-wavelength band-edge wavelength greater than the long-wavelength band-edge wavelength of the first reflection band 451. As Figure 4B As shown in , at an incident angle θ (e.g., 45 degrees), the first peak emission wavelength λg is between the first reflection band 451 and the third reflection band 455, the second peak emission wavelength λb is between the first reflection band 451 and the second reflection band 453, and the third peak emission wavelength λr is greater than the long wavelength band edge wavelength of the third reflection band 455. At an incident angle θ (e.g., 45 degrees), the long wavelength band edge wavelength of the first reflection band 451 is less than the peak emission wavelengths λg and λr of each of the first sub-pixel and the third sub-pixel; the long wavelength band edge wavelength of the second reflection band 453 is less than the peak emission wavelengths λg, λb, and λr of each of the first sub-pixel, the second sub-pixel, and the third sub-pixel; and the long wavelength band edge wavelength of the third reflection band 455 is less than the peak emission wavelength λr of the third sub-pixel.

[0073] In some embodiments, at normal incidence, the first reflection band 451 reflects at least 60% of a first light having a blocking polarization state and a wavelength distribution of an emission spectrum of a first subpixel in a plurality of subpixels (e.g., emission spectrum 441), and transmits at least 60% of the first light at an angle of incidence of 45 degrees. In some embodiments, at normal incidence, the second reflection band 453 reflects at least 60% of a second light having a blocking polarization state and a wavelength distribution of an emission spectrum of a second subpixel in a plurality of subpixels (e.g., emission spectrum 443), and transmits at least 60% of the second light at an angle of incidence of 45 degrees. In some embodiments, at normal incidence, the third reflection band 455 reflects at least 60% of a third light having a blocking polarization state and a wavelength distribution of an emission spectrum of a third subpixel in a plurality of subpixels (e.g., emission spectrum 345), and transmits at least 60% of the third light at an angle of incidence of 45 degrees.

[0074] The wavelength distribution N(λ) of the emission spectrum is defined such that N(λ)dλ is the fraction of photons emitted with wavelengths between λ and λ+dλ. This can be related to the power output of the emission spectrum as follows. The emission spectrum has a power output P that varies with wavelength λ, such that P(λ)dλ is the power output for wavelengths between λ and λ+dλ. The wavelength distribution is given by N(λ)=(N0 / λ)P(λ), where N0 is a normalizing constant selected so that the integral of N(λ) over wavelength is unity. The first reflection band may have a power output P that varies with wavelength T at a specified angle of incidence θ in the block polarization state. θ The transmittance varies with wavelength R θ (λ) varies with the reflectivity. If the wavelength of N(λ) is multiplied by R θIf the integral over N(λ) is at least 60%, then the reflection band reflects at least 60% of light having a block polarization state and a wavelength distribution of the emission spectrum at a specified angle of incidence θ. Similarly, if the wavelength at N(λ) is multiplied by T θ The integral over (λ) is at least 60%, then the reflection band transmits at least 60% of light having the block polarization state and the wavelength distribution of the emission spectrum at the specified angle of incidence θ.

[0075] The peak emission wavelengths λg, λb, and λr may be green (eg, 500 nm to 600 nm), blue (eg, 400 nm to 500 nm), and red (eg, 600 nm to 700 nm), respectively, although other wavelength ranges may alternatively be used.

[0076] In other embodiments, the reflective polarizer has fewer reflection bands (e.g., one or two reflection bands). For example, a single reflection band having a long wavelength band edge wavelength between λg and λr at normal incidence may be used. In this case, the short wavelength band edge wavelength may be less than λb. As another example, the reflective polarizer may include a first reflection band 451 and a second reflection band 453 and omit the third reflection band 455. As another example, the first reflection band 451 and the second reflection band 453 may be combined into a single broadband and may include a third reflection band 455 so that the reflective polarizer has two reflection bands.

[0077] In some embodiments, the reflective polarizer has at least a first reflection band. In some embodiments, at normal incidence, the first reflection band has a long wavelength band edge wavelength between the peak emission wavelengths of two sub-pixels in the plurality of sub-pixels. In some embodiments, at an incident angle of 45 degrees, the first reflection band has a long wavelength band edge wavelength that is less than the peak emission wavelength of each of the two sub-pixels.

[0078] Figure 5 5 is a schematic graph of the reflectivity of a reflective polarizer for light having a blocking polarization state as a function of wavelength at a fixed incident angle (e.g., 0 degrees or 45 degrees). In this case, the reflective polarizer has only one reflection band 551 in the visible spectrum. Reflection band 551 has a long wavelength band edge wavelength λ1L. Reflection band 551 may have, for example, a short wavelength band edge wavelength less than the peak emission wavelength of the blue sub-pixel or less than 400 nm. In other embodiments, the reflection band may have a shorter bandwidth (e.g., less than 150 nm, or less than 100 nm, or less than 80 nm). Figure 665 is a schematic graph of the reflectivity of a reflective polarizer for light having a block polarization state as a function of wavelength at a fixed incident angle (e.g., 0 degrees or 45 degrees). In this case, the reflective polarizer has only one reflection band 651 in the visible spectrum. The reflection band 651 has a long wavelength band edge wavelength λ1L and a short wavelength band edge wavelength λ1S.

[0079] Figure 7 75 is a schematic graph of the reflectivity of a reflective polarizer having a block polarization state as a function of wavelength at a fixed incident angle (e.g., 0 degrees or 45 degrees), the reflective polarizer having two reflection bands in the depicted wavelength range of the light (e.g., 400 nm to 700 nm). The first reflection band 751 has a long wavelength band edge wavelength λ1L and a short wavelength band edge wavelength λ1S. The second reflection band 755 has a long wavelength band edge wavelength λ3L and a short wavelength band edge wavelength λ3S, which second reflection band may also be referred to as a third reflection band because it may also include optional additional reflection bands having wavelengths lower than λ1S (e.g., reference 754). Fig. 9 ).

[0080] Figure 8 85 is a schematic graph of the reflectivity of a reflective polarizer having two reflection bands in the depicted wavelength range (e.g., 400 nm to 700 nm) of light with a block polarization state as a function of wavelength at a fixed incident angle (e.g., 0 degrees or 45 degrees). The first reflection band 851 has a long wavelength band edge wavelength λ1L and a short wavelength band edge wavelength λ1S. The second reflection band 853 has a long wavelength band edge wavelength λ2L and a short wavelength band edge wavelength λ2S.

[0081] Fig. 9 Schematic graph of the reflectivity of a reflective polarizer having a blocking polarization state as a function of wavelength at a fixed incident angle (e.g., 0 degrees or 45 degrees), the reflective polarizer having three reflection bands in the depicted wavelength range of the light (e.g., 400 nm to 700 nm). The first reflection band 951 has a long wavelength band edge wavelength λ1L and a short wavelength band edge wavelength λ1S. The second reflection band 953 has a long wavelength band edge wavelength λ2L and a short wavelength band edge wavelength λ2S. The third reflection band 955 has a long wavelength band edge wavelength λ3L and a short wavelength band edge wavelength λ3S. Each of the first, second, and third reflection bands 951, 953, and 955 may have a relatively narrow bandwidth (e.g., each less than 80 nm or each in the range of 10 nm to 80 nm). In other embodiments, some of the reflection bands may have a wider bandwidth. Fig.101 is a schematic graph of the reflectivity of a reflective polarizer having a block polarization state as a function of wavelength at a fixed incident angle (e.g., 0 degrees or 45 degrees), the reflective polarizer having three reflection bands in the depicted wavelength range of the light. The first reflection band 1051 has a long wavelength band edge wavelength λ1L and a short wavelength band edge wavelength λ1S. The second reflection band 1053 has a long wavelength band edge wavelength λ2L and a short wavelength band edge wavelength λ2S. The third reflection band 1055 has a long wavelength band edge wavelength λ3L and a short wavelength band edge wavelength λ3S. The short wavelength band edge wavelength λ2S of the second reflection band 1053 may, for example, be no more than 420 nm, or no more than 400 nm, or no more than 390 nm at normal incidence. The long wavelength band edge wavelength λ3L of the third reflection band 1055 may, for example, be at least 700 nm or at least 750 nm at normal incidence.

[0082] In some embodiments, at normal incidence, the first reflection band (e.g., reflection band 451, 651, 751, 851, 951, or 1051) has a bandwidth (λ1L-λ1S) of no more than 80 nm (e.g., in the range of 10 nm to 80 nm). In some embodiments, at normal incidence, the second reflection band (e.g., reflection band 453, 755, 853, 953, or 1053) has a bandwidth (λ2L-λ2S) of no more than 80 nm (e.g., in the range of 10 nm to 80 nm). In other embodiments, at normal incidence, the second reflection band (e.g., reflection band 453, 755, 853, 953, or 1053) has a bandwidth (λ2L-λ2S) greater than 80 nm (e.g., 100 nm or greater). In some embodiments, at normal incidence, the third reflection band (e.g., 455, 755, 955, or 1055) has a bandwidth (λ3L-λ3S) of no more than 80 nm (e.g., in the range of 10 nm to 80 nm). In other embodiments, at normal incidence, the third reflection band (e.g., reflection band 455, 755, 955, or 1055) has a bandwidth (λ3L-λ3S) greater than 80 nm (e.g., 100 nm or greater). In some embodiments, at normal incidence, the reflection band (e.g., reflection band 455, 755, 955, or 1055) has a long wavelength band edge wavelength λ3L, e.g., in the range of 700 nm to 2500 nm or in the range of 750 nm to 900 nm.

[0083] In some embodiments, the display panel includes a plurality of pixels, each of which includes a plurality of sub-pixels, and wherein the plurality of sub-pixels include red sub-pixels, green sub-pixels, and blue sub-pixels. The plurality of sub-pixels may also optionally include white sub-pixels. In some embodiments, at normal incidence, the long wavelength band edge wavelength λ1L of the first reflection band (e.g., reflection band 451, 551, 651, 751, 851, 951, or 1051) is between the peak emission wavelengths of the green sub-pixel and the red sub-pixel or between the peak emission wavelengths of the blue sub-pixel and the green sub-pixel. In some embodiments, the reflective polarizer has a second reflection band (e.g., reflection band 453, 853, 953, or 1053), and at normal incidence, the second reflection band has a long wavelength band edge wavelength λ2L between the peak emission wavelengths of the blue sub-pixel and the green sub-pixel. In some embodiments, the reflective polarizer has a third reflection band (e.g., reflection band 455, 755, 955, or 1055), and at normal incidence, the third reflection band has a short wavelength band edge wavelength λ3S that is greater than the long wavelength band edge wavelength of the first reflection band and less than the peak emission wavelength of the red sub-pixel.

[0084] In some embodiments, at normal incidence, the second reflection band has a long wavelength band edge wavelength λ2L in the range of 440nm to 500nm; the short wavelength band edge wavelength λ1S of the first reflection band is at least 10nm greater than the long wavelength band edge wavelength λ2L of the second reflection band (λ1S-λ2L≥10nm); the third reflection band has a short wavelength band edge wavelength λ3S in the range of 580nm to 640nm; and the short wavelength band edge wavelength λ3S of the third reflection band is at least 10nm greater than the long wavelength band edge wavelength λ1L of the first reflection band (λ3S-λ1L≥10nm). In some embodiments, at normal incidence, the first reflection band has a short wavelength band edge wavelength λ1S in the range of 480nm to 510nm and has a long wavelength band edge wavelength λ1L in the range of 550nm to 570nm. In some embodiments, at normal incidence, the first reflection band has a bandwidth λ1L-λ1S of no more than 80nm.

[0085] Fig.11 301 is a schematic diagram of the transmission spectrum of a reflective polarizer. In this figure, the transmittance is plotted against the wavelength λ in nanometers, with the wavelength axis extending in the range of 400nm to 700nm. Curve 301 may represent the measured transmittance of light polarized along the block axis at normal incidence. The depicted reflective polarizer selectively reflects light within a narrow band in a portion of the green region of the spectrum, as evidenced by the relatively low transmittance in the reflection band 301a indicated by curve 301.

[0086] In order to quantify the relevant characteristics of curve 301, Fig.11 301, a baseline value B of curve 301, a peak value P of curve 301 (in this case, peak value P corresponds to the transmittance minimum of reflection band 301a shown at point p3), and an intermediate value H of curve 301 halfway between P and B. Curve 301 intersects the value H at points p1 and p2. These points are located on the short wavelength band edge 307 and the long wavelength band edge 309 of reflection band 301a, respectively, and define the short wavelength band edge wavelength λ2 and the long wavelength band edge wavelength λ3. The short wavelength band edge wavelength and the long wavelength band edge wavelength can be used to calculate two other parameters of interest: the width of the reflection band 301a (full width at half maximum or "FWHM"), which is equal to λ3-λ2; and the center wavelength λc of the reflection band 301a, which is equal to (λ2+λ3) / 2. It should be noted that the center wavelength λc can be the same as or different from the peak wavelength (reference point p3) of the reflection band 301a, depending on the degree of symmetry or asymmetry of the reflection band 301a. In many cases, the absorbance of the reflective polarizer is negligible, and thus the reflectance is approximately 100% minus the transmittance.The band edge wavelength can be similarly defined by a plot of reflectance versus wavelength.

[0087] If one of the two reflection bands reflects shorter wavelengths and has a long wavelength band edge wavelength as defined above, the other of the reflection bands reflects longer wavelengths and has a short wavelength band edge wavelength as defined above, and the short wavelength band edge wavelength of the reflection band that reflects longer wavelengths is greater than the long wavelength band edge wavelength of the reflection band that reflects shorter wavelengths, then the two reflection bands can be described as substantially non-overlapping. It will be understood that the tails of the wavelength distribution of the reflection bands can overlap, where the tails have low reflectivity in the light-blocking state (e.g., the peak reflectivity across the tails is less than 40%, or less than 30%, or less than 20%, or less than 10%), and if the short wavelength band edge wavelength of the reflection band that reflects longer wavelengths is greater than the long wavelength band edge wavelength of the reflection band that reflects shorter wavelengths, then the reflection bands can still be described as substantially non-overlapping.

[0088] The transmittance of an optical element generally refers to the intensity of light transmitted divided by the intensity of light incident (for a given wavelength of light, incident direction, etc.), but can be expressed as "external transmittance" or "internal transmittance". The external transmittance of an optical element is the transmittance of the optical element when it is immersed in air and no correction is made for the Fresnel reflection at the air / element interface in front of the element or the Fresnel reflection at the element / air interface at the back of the element. The internal transmittance of an optical element is the transmittance of the element when the Fresnel reflections at the front and back surfaces of the element have been removed. The removal of the front Fresnel reflection and the back Fresnel reflection can be accomplished by calculation (e.g., by subtracting an appropriate function from the external transmission spectrum) or by experiment. For many types of polymers and glass materials, the Fresnel reflection is about 4% to 6% at each of the two external surfaces (for normal or quasi-normal angles of incidence), which results in a downward shift of the external transmittance relative to the internal transmittance by about 10%. Fig.11 It is not specified which of these transmittances is used, therefore this may generally apply to either the internal transmittance or the external transmittance. If transmittance is mentioned herein without specifying internal or external, it may be assumed that the transmittance refers to the external transmittance unless the context indicates otherwise.

[0089] The reflective polarizer of the present description can be a multilayer optical film including an optical stack including a plurality of optical repeating units, wherein each optical repeating unit includes a first polymer layer and a second polymer layer. Fig.12 is a schematic perspective view of an exemplary optical repeating unit (ORU) of multilayer optical film 1200 . Fig.12 Only two layers of the multilayer optical film 1200 are depicted, which may include tens or hundreds of such layers arranged in one or more adjacent groupings or stacks. The film 1200 includes individual microlayers 1202, 1204, where a "microlayer" or "interference layer" refers to a layer that is thin enough so that light reflected at multiple interfaces between such layers interferes constructively or destructively to impart the desired reflective or transmissive properties to the multilayer optical film. The microlayers 1202, 1204 may together represent an optical repeating unit (ORU) of the multilayer stack, an ORU being the smallest group of layers that recurs in a repeating pattern throughout the thickness of the stack. The microlayers have different refractive index properties so that some light is reflected at the interfaces between adjacent microlayers. For optical films designed to reflect ultraviolet, visible, or near infrared wavelengths, the optical thickness (i.e., physical thickness multiplied by the associated refractive index) of each microlayer is typically less than about 1 micron. However, thicker layers may be included as desired, such as skin layers at the outer surface of the film or protective boundary layers (PBLs) disposed within the film separating groupings of microlayers. In some embodiments, only a single grouping or stack of microlayers is included in the optical films of the present description.

[0090] One of the microlayers (e.g., Figure 1 The microlayer 1202, or Fig.13 The refractive indices of the "A" layer for light polarized along the principal x-axis, y-axis, and z-axis are n1x, n1y, and n1z, respectively. The mutually orthogonal x-axis, y-axis, and z-axis may, for example, correspond to the principal directions of the dielectric tensor of the material. Fig.12 and Fig.13 The x-axis and y-axis may or may not correspond to Figure 2 In many embodiments, the principal directions of the different materials coincide, but this need not be the case. Adjacent microlayers (e.g., Fig.12 The microlayer 1204, or Fig.13 The "B" layers in the film (the "B" layers in the film) have refractive indices along the same axes, respectively, n2x, n2y, and n2z. The difference in refractive index between these layers is Δnx (=n1x-n2x) along the x-direction, Δny (=n1y-n2y) along the y-direction, and Δnz (=n1z-n2z) along the z-direction. The nature of these refractive index differences, together with the number of microlayers in the film (or in a given stack of films) and their thickness distribution, controls the reflective and transmissive properties of the film (or a given stack of films). For example, if adjacent microlayers have a large refractive index mismatch along one in-plane direction (Δnx is large) and a small refractive index mismatch along an orthogonal in-plane direction (Δny≈0), the film or grouping can act as a reflective polarizer for normally incident light.

[0091] If desired, the refractive index difference (Δnz) between adjacent microlayers for light polarized along the z-axis can also be tailored to achieve desired reflective properties for the p-polarized component of obliquely incident light. In order to maintain the paraxial reflectivity of p-polarized light incident at an oblique angle, the z-index mismatch Δnz between the microlayers can be controlled to be substantially less than the maximum in-plane refractive index difference Δnx, such that |Δnz|≤0.5*|Δnx|. Alternatively, |Δnz|≤0.25*|Δnx|. A z-index mismatch of zero or nearly zero magnitude produces an interface between the microlayers whose reflectivity for p-polarized light is constant or nearly constant with the angle of incidence. In addition, the z-index mismatch Δnz can be controlled to have an opposite polarity compared to the in-plane refractive index difference Δnx, for example, when Δnx>0, Δnz<0. This condition produces an interface whose reflectivity for p-polarized light increases with increasing angle of incidence, and the same is true for s-polarized light. If Δnz>0, then the reflectivity of p-polarized light decreases with the angle of incidence. The above relationship of course also applies to the relationship involving Δnz and Δny, for example, in cases where significant reflectivity and transmittance along two principal in-plane axes are desired (such as a partially polarized film whose pass axis has significant reflectivity at normal incidence).

[0092] exist Fig.13 In the schematic side view of FIG. 1 , more inner layers of the multilayer optical film 1310 are shown so that multiple ORUs can be observed. The film is shown in a local xyz Cartesian coordinate system, where the film extends parallel to the x-axis and the y-axis, and the z-axis is perpendicular to the film and its constituent layers and parallel to the thickness axis of the film.

[0093] exist Fig.13 , microlayers, which may be referred to as alternating interference layers, are labeled "A" or "B," with the "A" layers being composed of one material and the "B" layers being composed of a different material, and the layers being stacked in an alternating arrangement to form optical repeating units or unit cells ORU 1, ORU 2, ... ORU 6, as shown. In many embodiments, if high reflectivity is desired, a multilayer optical film composed entirely of polymeric materials will include more than 6 optical repeating units. In some embodiments, the "A" layers are composed of a first polymer and the "B" layers are composed of a different second polymer. The "A" and "B" layers may then be referred to as alternating polymer interference layers. The multilayer optical film 1310 is shown as having a significantly thicker layer 1312, which may represent an outer layer or protective boundary layer ("PBL," see U.S. Pat. No. 6,783,349 (Neavin et al.)) that may separate the stack of microlayers shown in the figure from another stack or grouping of microlayers, if present. The multilayer optical film 1310 includes a single stack 1313 having opposing first and second sides 1315 , 1317 .

[0094] An interference layer or microlayer can be described as reflecting and transmitting light primarily by optical interference when the reflectivity and transmittance of the interference layer can be reasonably described by or is reasonably accurately modeled by optical interference.

[0095] In some embodiments, the thicker layer 1312 is optically thick in that it is too thick to significantly contribute to the constructive and destructive interference provided by the optical stack. In some embodiments, the optically thick layer has at least one of a physical thickness and an optical thickness greater than 1 micron, or at least 2 microns, or at least 3 microns, or at least 5 microns. If a thickness is mentioned without specifying whether the thickness is an optical thickness or a physical thickness, it can be assumed that the thickness is a physical thickness.

[0096] In some cases, the thickness and refractive index values ​​of a given stack or group of microlayers or interference layers correspond to a quarter wave stack, i.e., arranged as an ORU, each ORU having two adjacent microlayers of equal optical thickness, such ORUs can effectively reflect light by constructive interference, the wavelength λ of which is twice the total optical thickness (physical thickness multiplied by refractive index) of the optical repeat unit (primary wave or first harmonic). In the case of a reflective polarizer, the refractive index used to determine the optical thickness is the refractive index along the block axis of the reflective polarizer. A quarter wave stack in which the two adjacent microlayers in each ORU have equal optical thickness is said to have an "f ratio" of 0.5 or 50%. "F ratio" in this regard refers to the ratio of the optical thickness of component layer "A" to the optical thickness of the entire optical repeat unit, assuming that component layer "A" has a higher refractive index than component layer "B"; if layer "B" has a higher refractive index, then the f ratio is the ratio of the optical thickness of component layer "B" to the optical thickness of the entire optical repeat unit. It is often considered desirable to use an f-ratio of 50% because this maximizes the reflectivity of the 1st order (primary) reflection band of the microlayer stack. However, an f-ratio of 50% suppresses or eliminates the 2nd order (second harmonic) reflection band (and higher orders). This is also generally considered desirable in many applications; however, as further described elsewhere herein, since the second harmonic of the primary reflection band can be used to provide additional flexibility in achieving a desired color output, it may not be necessary to suppress the 2nd order reflection band in some applications. For example, in some embodiments, the first order harmonic or primary reflection band is used to provide reflection in the red and near infrared, and the second harmonic of this reflection band is used to provide reflection in the blue wavelength range. For example, the relative reflectivity of the primary reflection band and harmonics of the primary reflection band as a function of the f-ratio is described in U.S. Pat. No. 9,279,921 (Kivel et al.).

[0097] In some embodiments, for example, the f ratio is in the range of 0.05 to 0.4 or in the range of 0.6 to 0.95. In other embodiments, the f ratio is in the range of, for example, 0.4 to 0.6. Fig.13 In the embodiments of the present invention, the "A" layer is generally depicted as being thinner than the "B" layer. The optical thickness (OT1, OT2, etc.) of each depicted optical repeating unit (ORU 1, ORU 2, etc.) is equal to the sum of the optical thicknesses of its constituent layers "A" and "B", and each optical repeating unit provides a 1st order reflection of light having a wavelength λ that is twice the total optical thickness of the ORU.

[0098] To achieve the desired reflectivity with an appropriate number of layers, adjacent microlayers may exhibit a refractive index difference (|Δnx|) of, for example, at least 0.05, or at least 0.1, or at least 0.15 for light polarized along the x-axis. Adjacent microlayers may exhibit a smaller refractive index difference (|Δny|) for light polarized along the y-axis. For example, in some embodiments, |Δny| is no more than 0.04, or no more than 0.02, or no more than 0.01. In some embodiments, adjacent microlayers may exhibit a refractive index match or mismatch (Δnz=0 or |Δnz| is large) along the z-axis, and the mismatch may have the same or opposite polarity or sign as the in-plane refractive index mismatch. Whether the reflectivity of the p-polarization component of oblique incident light increases, decreases, or remains unchanged with increasing incident angle can be controlled by such customization of Δnz. The refractive index and refractive index difference may be specified at a fixed reference wavelength (e.g., 532nm or 633nm) or may be specified for each optical repeat unit at the wavelength at which the optical repeat unit is configured to reflect.

[0099] In some embodiments, the total number of optical repeat units in the optical stack is at least 25, or at least 30, or at least 35, or at least 40. In some embodiments, the total number of optical repeat units is no more than 300, or no more than 200, or no more than 180, or, no more than 160, or no more than 150. A larger number of optical repeat units may be used in embodiments with smaller (or closer to unity) f-ratios, while a smaller number of optical repeat units may be used in embodiments with f-ratios approaching 0.5.

[0100] At least some of the microlayers in at least one packet of the multilayer optical film can be birefringent, for example, uniaxially birefringent. In some cases, each ORU can include one birefringent microlayer and a second microlayer that is isotropic or has a small amount of birefringence relative to the other microlayer. In alternative cases, each ORU can include two birefringent microlayers.

[0101] The multilayer optical film can be made of any suitable light-transmitting material, but in many cases it is beneficial to use a low-absorbing polymer material. By using such materials, the absorption of the microlayer stack at visible and infrared wavelengths can be small or negligible, so that at any given wavelength and for any specified angle of incidence and polarization state, the sum of the reflectivity and transmittance of the stack (or the optical film to which it belongs) is about 100%, that is, R+T≈100% or R≈100%-T.

[0102] Suitable materials for the alternating interference layers include, for example, polyethylene naphthalate (PEN), copolymers comprising PEN and polyesters such as polyethylene terephthalate (PET) or dibenzoic acid, glycol-modified polyethylene terephthalate, polycarbonate (PC), or blends of these classes of materials.

[0103] Exemplary multilayer optical films are composed of polymer materials and can be prepared using coextrusion, casting and orientation processes. Reference is made to U.S. Patent 5,882,774 (Jonza et al.) "Optical Film", U.S. Patent 6,179,948 (Merrill et al.) "Optical Film and Process for Manufacture Thereof", U.S. Patent 6,783,349 (Neavin et al.) "Apparatus for Making Multilayer Optical Films", and Patent Application Publication US 2011 / 0272849 (Neavin et al.) "Feedblock for Manufacturing Multilayer Polymeric Films" for manufacture. The multilayer optical film can be formed by coextrusion of polymers described in any of the above references. The polymers of the various layers can be selected to have similar rheological properties (such as melt viscosity) so that they can be coextruded without significant fluid disturbance. Extrusion conditions are selected so that the respective polymers are adequately fed, melted, mixed and pumped as a feed stream or melt stream in a continuous and stable manner. The temperature used to form and maintain each melt stream can be selected to be within a range that avoids freezing, crystallization or undue high pressure drop at the low end of the temperature range and avoids material degradation at the high end of the range.

[0104] Briefly, a manufacturing method may include: (a) providing at least a first resin stream and a second resin stream, the first resin stream and the second resin stream corresponding to a first polymer and a second polymer to be used in a finished film; (b) separating the first stream and the second stream into a plurality of layers using a suitable feed block, such as a feed block comprising: (i) a gradient plate comprising a first flow channel and a second flow channel, wherein the cross-sectional area of ​​the first channel changes from a first position to a second position along the flow channel, and (ii) a feed tube plate having a first flow channel in fluid communication with the first flow channel. a first plurality of conduits and a second plurality of conduits in fluid communication with a second flow channel, each conduit feeding its own respective slot die, each conduit having a first end and a second end, the first end of the conduit being in fluid communication with the flow channel and the second end of the conduit being in fluid communication with the slot die, and (iii) optionally, an axial rod heater positioned proximal to the conduit; (c) passing the composite material stream through an extrusion die to form a multilayer web, wherein each layer is substantially parallel to a major surface of an adjacent layer; and (d) casting the multilayer web onto a chilled roller (sometimes referred to as a casting wheel or casting drum) to form a cast multilayer film. The cast film may have the same number of layers as the finished film, but the layers of the cast film are typically much thicker than the layers of the finished film. In addition, the layers of the cast film are typically all isotropic. Multilayer optical films having controlled low frequency variations in reflectivity and transmittance over a wide wavelength range can be achieved by thermal zone control of the axial rod heater, see, for example, U.S. Patent 6,783,349 (Neavin et al.).

[0105] After cooling the multilayer web on the cooling roll, it can be drawn or stretched to produce a finished or nearly finished multilayer optical film. Drawing or stretching achieves two goals: this thins the layers to their desired final thickness; and this can orient the layers so that at least some of the layers become birefringent. Orientation or stretching can be achieved in the cross-web direction (e.g., via a tenter), in the longitudinal direction (e.g., via a length orientation machine), or any combination thereof (whether simultaneously or sequentially). If stretched in only one direction, the stretching can be "unconstrained" (where the film is allowed to relax in size in the in-plane direction perpendicular to the stretching direction) or "constrained" (where the film is constrained and thus not allowed to relax in size in the in-plane direction perpendicular to the stretching direction). The stretching may be asymmetric between orthogonal in-plane directions so that the resulting film will have a polarization-dependent reflectivity. In some embodiments, the film can be stretched by a batch process. In any case, subsequent or simultaneous drawing reduction, stress or strain balancing, heat setting and other processing operations may also be applied to the film.

[0106] The film can be formed by coextruding one or more groups of films consisting of a large number of microlayers to form a grouping generally referred to as a generally alternating isotropic and birefringent layer. The grouping is generally formed in a roll process, wherein the cross-sectional dimension is generally marked as the transverse direction (TD), and the dimension along the length of the roll is referred to as the longitudinal direction (MD). In addition, the grouping can be carefully stretched in the longitudinal and transverse directions in a carefully controlled temperature zone during the forming process to affect the birefringent layer in a process generally referred to as a tentering process. In addition, the tentering process can provide a linear transverse stretch or a parabolic stretch of the grouping when they are formed. A controlled inward linear retraction generally referred to as "toe-in" can be used to allow a controlled contraction during the cooling zone. The process can be used to provide, for example, 30 to 600 or more layers to achieve the desired optical effect, and an external "skin" layer can also be included as required.

[0107] In some embodiments, the plurality of alternating polymer interference layers comprises alternating first and second polymer layers, wherein the first polymer layers are substantially uniaxially oriented, which may be understood to mean that the refractive index in a first in-plane direction and a thickness direction are within 0.02 of each other, and the absolute difference between the refractive index in an orthogonal second in-plane direction and the first in-plane direction is at least 0.05. In some embodiments, the second polymer layers are substantially isotropic. Substantially isotropic may be understood to mean that the refractive index in each of three mutually orthogonal directions is within 0.02 of each other. In some embodiments, the reflective polarizer has at least one layer having a refractive index that is substantially the same in the length direction and in the thickness direction (e.g., within 0.02 or within 0.01), but the refractive index is substantially different from the refractive index in the width direction (e.g., the difference is at least 0.05, or at least 0.1, or at least 0.15). In some embodiments, the reflective polarizer is a substantially uniaxially drawn film, and the uniaxiality characteristic U is at least 0.7, or at least 0.8, or at least 0.85, where U = (1 / MDDR - 1) / (TDDR 1 / 2 –1), where MDDR is defined as the machine direction draw ratio and TDDR is defined as the transverse direction draw ratio. Such substantially uniaxially oriented multilayer optical films are described in U.S. Patent Application 2010 / 0254002 (Merrill et al.) and can be obtained by orienting the multilayer film using a parabolic tenter.

[0108] In some embodiments, the optical repeating unit has an optical thickness that varies substantially continuously over each optical thickness range that provides a reflection band. The thickness variation can be selected to provide a sharp band edge such as described in US6,157,490 (Wheatley et al.), or can be selected to provide a more gradual transition from high reflectivity to low reflectivity.

[0109] Figures 14 to 17is a schematic graph of layer thickness distribution in a reflective polarizer. The thickness of an optical repeating unit (ORU) is plotted relative to the number of ORUs. In some embodiments, the reflective polarizer includes a first plurality of alternating interference layers, a second plurality of alternating interference layers, and a third plurality of alternating interference layers that do not intersect each other, wherein the first plurality of alternating interference layers provide a first reflection band, the second plurality of alternating interference layers provide a second reflection band, and the third plurality of alternating interference layers provide a third reflection band. In some embodiments, the reflective polarizer includes a plurality of alternating polymer interference layers, the plurality of alternating polymer interference layers including an outermost first interference layer and a second interference layer, wherein the plurality of alternating polymer interference layers include a first plurality of alternating interference layers, a second plurality of alternating interference layers, and a third plurality of alternating interference layers that do not intersect each other. When one of the first plurality of alternating interference layers, the second plurality of alternating interference layers, and the third plurality of alternating interference layers has no layer or is a layer on another of the first plurality of alternating interference layers, the second plurality of alternating interference layers, and the third plurality of alternating interference layers, the first plurality of alternating interference layers, the second plurality of alternating interference layers, and the third plurality of alternating interference layers do not intersect or do not intersect each other.

[0110] exist Fig.14 , a first plurality of alternating interference layers 1457, a second plurality of alternating interference layers 1458, and a third plurality of alternating interference layers 1459 are depicted, respectively. The first plurality of alternating interference layers 1457 are disposed between the second plurality of alternating interference layers 1458 and the third plurality of alternating interference layers 1459. Fig.14 In the embodiment of the present invention, a thinner layer (e.g., reflecting blue) is disposed at one side of the reflective polarizer, a thicker layer (e.g., reflecting red) is disposed on the opposite side of the reflective polarizer, and an intermediate thickness layer (e.g., reflecting green) is disposed near the center of the reflective polarizer. In some embodiments, this may be preferred, for example, for ease of manufacturing. In other embodiments, it may be preferred to have the intermediate thickness layer closest to one side of the reflective polarizer because this allows that layer to reflect the most photopic wavelengths closest to the display panel.

[0111] exist Fig.15 , a first plurality of alternating interference layers 1557, a second plurality of alternating interference layers 1558, and a third plurality of alternating interference layers 1559 are shown, respectively. The second plurality of alternating interference layers 1558 are disposed between the first plurality of alternating interference layers 1557 and the third plurality of alternating interference layers 1559. The first plurality of alternating interference layers 1557 comprises the outermost interference layers (e.g., the outermost first interference layers) of the reflective polarizer, and the third plurality of alternating interference layers 1559 comprises the outermost interference layers (e.g., the outermost second interference layers) of the reflective polarizer. Fig.16, a first plurality of alternating interference layers 1657, a second plurality of alternating interference layers 1658, and a third plurality of alternating interference layers 1659 are respectively shown. Third plurality of alternating interference layers 1658 are disposed between first plurality of alternating interference layers 1657 and third plurality of alternating interference layers 1659. First plurality of alternating interference layers 1657 include outermost interference layers (e.g., outermost first interference layers) of the reflective polarizer, and second plurality of alternating interference layers 1658 include outermost interference layers (e.g., outermost second interference layers) of the reflective polarizer.

[0112] In some embodiments, the circular polarizer includes a retarder, an absorbing polarizer, and a reflective polarizer disposed between the retarder and the absorbing polarizer. In some embodiments, the first plurality of alternating interference layers (e.g., 1557 or 1657) includes an outermost first interference layer, wherein the outermost first interference layer faces the retarder. In some embodiments, the first plurality of alternating interference layers (e.g., 1557 or 1657) is disposed closer to the display panel than the second plurality of alternating interference layers (e.g., 1558 or 1658), and / or the first plurality of alternating interference layers (e.g., 1557 or 1657) is disposed closer to the display panel than the third plurality of alternating interference layers (e.g., 1559 or 1659).

[0113] In some embodiments, each of the first reflection band, the second reflection band, and the third reflection band is an original reflection band, which may also be referred to as a first-order harmonic reflection band. Figures 14 to 16 The first plurality of alternating interference layers, the second plurality of alternating interference layers, and the third plurality of alternating interference layers of each of the plurality of alternating interference layers may produce substantially non-overlapping first, second, and third reflection bands, wherein each of the first, second, and third reflection bands is a first-order harmonic reflection band. For example, in some embodiments, FIG. 4A to FIG. 4B as well as Figures 5 to 11 The reflection bands depicted in can be first-order harmonic reflection bands or original reflection bands.

[0114] In other embodiments, a first harmonic reflection band may be used for each of the first reflection band and the third reflection band, and the second reflection band may be a second harmonic of the third reflection band. Fig.1717 is a schematic graph of layer thickness distribution of a reflective polarizer having substantially non-overlapping first, second, and third reflection bands. The reflective polarizer includes a non-intersecting first plurality of alternating interference layers 1757 and a second plurality of alternating interference layers 1758, wherein the first plurality of alternating interference layers 1757 provide a first reflection band and the second plurality of alternating interference layers 1758 provide a second reflection band and a third reflection band. The first and third reflection bands are original reflection bands, and the second reflection band is a second harmonic of the third reflection band. For example, by having Fig.17 The reflective polarizer with the layer thickness distribution schematically shown in FIG. Fig.10 The first reflection band 1051 and the third reflection band 1055 may be original or first-order harmonic reflection bands, and the second reflection band 1053 may be a second-order harmonic of the third reflection band 1055.

[0115] Fig.18 1 is a schematic cross-sectional view of a reflective polarizer 1810 including a plurality of alternating polymer interference layers including an outermost first interference layer 1861 and a second interference layer 1862 as the outermost (closest to the outermost major surface) interference layers of the reflective polarizer 1810. Optional outermost protective boundary layers 1863 and 1868 are included in the illustrated embodiment. The optional outermost protective boundary layers 1863 and 1868 are not interference layers because the layers are too thick to contribute significantly to constructive and destructive interference in the visible wavelength range. Typically, such non-interference layers have an optical thickness greater than 1 micron and / or a thickness greater than 2 microns. In some embodiments, the thickness of each layer disposed between the outermost first interference layer 1861 and the second interference layer 1862 in the reflective polarizer 1810 is less than 1 micron, or less than 500 nm, or less than 300 nm, or less than 200 nm. The outermost first interference layer 1861 and the second interference layer 1862 may also each have a thickness within these ranges (eg, less than 300 nm or less than 200 nm).

[0116] The plurality of alternating polymer interference layers includes a first plurality of alternating interference layers 1857, a second plurality of alternating interference layers 1858, and a third plurality of alternating interference layers 1859 that are mutually non-intersecting. In some embodiments, the plurality of alternating polymer interference layers has a substantially non-overlapping first reflection band, a second reflection band, and a third reflection band, wherein each of the first reflection band, the second reflection band, and the third reflection band is a first-order harmonic reflection band. In some embodiments, the first plurality of alternating interference layers 1857 provide a first reflection band, the second plurality of alternating interference layers 1858 provide a second reflection band, and the third plurality of alternating interference layers 1859 provide a third reflection band. The first plurality of alternating interference layers 1857, the second plurality of alternating interference layers 1858, and the third plurality of alternating interference layers 1859 can be arranged in other orders. For example, the first plurality of alternating interference layers 1857 can be disposed between the second plurality of alternating interference layers 1858 and the third plurality of alternating interference layers 1859. In some embodiments, the circular polarizer includes a reflective polarizer 1810 disposed between an absorbing polarizer and a retarder. In some embodiments, a first plurality of alternating interference layers 1857 that can reflect green wavelengths, for example, include an outermost first interference layer 1861, wherein the outermost first interference layer 1861 faces the retarder. In some embodiments, the display includes a reflective polarizer 1810 disposed to receive the light output of a display panel (e.g., imaging light or spatially modulated light generated by the display panel for viewing by a viewer), and the outermost first interference layer 1861 faces the display panel.

[0117] In the illustrated embodiment, optional additional layers 1864 and 1866 are included between the first plurality of alternating interference layers 1857 and the second plurality of alternating interference layers 1858 and between the second plurality of alternating interference layers 1858 and the third plurality of alternating interference layers 1859. Such layers may result from protective boundary layers included in the grouping of the first plurality of alternating interference layers 1857, the second plurality of alternating interference layers 1858, and the third plurality of alternating interference layers 1859. In some embodiments, each of the optional additional layers 1864 and 1866 has a thickness of less than 1 micron or a thickness of less than 500 nm. In contrast, protective boundary layers traditionally have a thickness of 2 to 3 microns. Thinner additional layers 1864 and 1866 may be used to reduce the thickness of the reflective polarizer. In some embodiments, optional additional layers 1864 and 1866 are omitted. For example, first plurality of alternating interference layers 1857, second plurality of alternating interference layers 1858, and third plurality of alternating interference layers 1859 can be formed as a single grouping of adjacent interference layers. In some such embodiments, or in other embodiments, the thickness of each layer disposed between the outermost first interference layer 1861 and second interference layer 1862 in reflective polarizer 1810 can be less than 300 nm or less than 200 nm. In some cases, it is preferred to use a single grouping omitting optional additional layers 1864 and 1866 in order to reduce the thickness of reflective polarizer 1800 (e.g., to less than 80 microns, or less than 60 microns, or less than 50 microns), so that each of first plurality of alternating interference layers 1857, second plurality of alternating interference layers 1858, and third plurality of alternating interference layers 1859 can be placed close to the same distance from the display panel. In other cases, for manufacturing flexibility, for example, including optional additional layers 1864 and 1866 can be preferred. In such cases, additional layers 1864 and 1866 are preferably thin (eg, having a thickness of less than 1 micron, or less than 500 nm, or in the range of 300 nm to 500 nm, or to 1 micron).

[0118] In some embodiments, the circular polarizer includes a reflective polarizer disposed between the absorbing polarizer and the retarder. The circular polarizer can be an integral optical stack. An integral optical stack is a stack of optical layers, wherein each layer in the optical stack is bonded to another layer in the optical stack. In some embodiments, the retarder is directly coated on the major surface of the reflective polarizer, which can be an integrally formed reflective polarizer, and the absorbing polarizer is bonded to the reflective polarizer on the opposite major surface of the reflective polarizer by an optically clear adhesive (e.g., an adhesive having a haze of (e.g.) less than 5% or less than 2% as determined by the ASTM D1003-13 standard and a light transmittance of (e.g.) at least 80% or at least 90% as determined by the ASTM D1003-13 standard).

[0119] In some embodiments, the reflective polarizer is integrally formed. As used herein, a first element that is "integrally formed" with a second element means that the first element and the second element are manufactured together, rather than being manufactured separately and subsequently combined. Integral formation includes manufacturing the first element and then manufacturing the second element on the first element. An optical film (e.g., a reflective polarizer) comprising multiple layers is integrally formed, provided that the layers are manufactured together (e.g., combined into a molten stream and then cast onto a cooling roller to form a cast film having each of the layers, and then orienting the cast film), rather than being manufactured separately and subsequently combined. An additional layer that is not integral to the integrally formed multilayer optical film means that the additional layer is not integrally formed with the multilayer optical film. For example, the additional layer may be formed separately and then adhered (e.g., laminated using an optically clear adhesive) to the multilayer optical film.

[0120] In some embodiments, the reflective polarizer or circular polarizer is substantially flat. In other embodiments, the reflective polarizer or circular polarizer is curved to conform to the shape of the output surface of the curved display panel. In some embodiments, the reflective polarizer or circular polarizer substantially conforms to the output surface of the display panel, whether substantially flat or curved.

[0121] Fig.191 is a schematic cross-sectional view of a circular polarizer 1900, which includes a retarder 1906, an absorptive polarizer 1908, and a reflective polarizer 1910 disposed between the retarder 1906 and the absorptive polarizer 1908. The reflective polarizer 1910 can be any of the reflective polarizers of the present specification. In some embodiments, the reflective polarizer 1910 has a transmission axis substantially aligned with the transmission axis of the absorptive polarizer 1908, as further described elsewhere herein. In some embodiments, the retarder 1906 is a quarter-wave retarder at one or more wavelengths in the visible range (400nm to 700nm) and has a fast axis substantially aligned at 45 degrees with the transmission axis of the reflective polarizer 1910. In this context, substantially aligned can be understood to mean aligned within 20 degrees. In the illustrated embodiment, an optically transparent adhesive layer 1972 joins the absorptive polarizer 1908 and the reflective polarizer 1910 together. In other embodiments, an absorbing polarizer layer may be coated onto a reflective polarizer, the reflective polarizer may then be oriented, and the absorbing polarizer and reflective polarizer may then be oriented in the same process step. In this case, the adhesive layer 1972 may be omitted, and the reflective polarizer 1910 and the absorbing polarizer 1908 may be directly bonded to each other. In the illustrated embodiment, the retarder 1906 is disposed directly on the reflective polarizer 1910. For example, the retarder 1906 may be formed from a coating applied to the reflective polarizer 1910. In other embodiments, the retarder 1906 is formed separately and then adhered to the reflective polarizer by an optically clear adhesive layer. In other embodiments, additional layers, such as a diffuser layer, are included.

[0122] In some cases, luminance exhibits variation with viewing angle due to different walk-off distances relative to areas of relatively low reflectivity and relatively high reflectivity as viewing angle changes. This "luminance ripple" can be reduced or substantially eliminated, for example, by incorporating a diffuser between the reflective polarizer and the display panel (e.g., in a circular polarizer located between the reflective polarizer and the retarder).

[0123] Fig. 202000, which includes: a retarder 2006, which can be a quarter wave retarder as further described elsewhere herein; an absorbing polarizer 2008; and a reflective polarizer 2010, which is disposed between the retarder 2006 and the absorbing polarizer 2008; and a diffuser 2075, which is disposed between the reflective polarizer 2010 and the retarder 2006. The reflective polarizer 2010 can be any of the reflective polarizers of the present specification, and can be aligned with the absorbing polarizer 2008 and the retarder 2006 as described elsewhere herein (e.g., as described for the circular polarizer 1900). An optically clear adhesive layer 2072 joins the absorbing polarizer 2008 and the reflective polarizer 2010 together. The diffuser 2075 can be, for example, a beaded diffuser (e.g., particles in an adhesive layer) and / or can be, for example, a layer having an optically diffuse microstructure surface. The circular polarizer 2000 can be disposed in a display such that the diffuser 2075 is disposed between the reflective polarizer 2010 and the display panel. In other embodiments, the display can include a circular polarizer without a diffuser, and the display can include a diffuser disposed at some other location between the reflective polarizer and the display panel. For example, the circular polarizer can be attached to the display panel using an adhesive that includes diffusing particles.

[0124] In some embodiments, the circular polarizer 1900 and / or the circular polarizer 2100 is an integral optical stack wherein each layer in the optical stack is bonded to another layer in the optical stack.

[0125] In some embodiments, the reflective polarizer (e.g., reflective polarizer 1910 or reflective polarizer 2010 or any reflective polarizer described elsewhere herein) has a thickness t1 in the range of 10 microns to 80 microns. In some embodiments, thickness t1 is less than 60 microns or less than 50 microns. In some embodiments, the circular polarizer (e.g., circular polarizer 1900 or circular polarizer 2000 or any circular polarizer described elsewhere herein) has a thickness in the range of 30 microns to 500 microns, or a thickness in the range of 50 microns to 400 microns.

[0126] In some embodiments, the absorbing polarizer has an average transmittance in the range of 40% to 60%, or an average transmittance in the range of 44% to 60%, for normally incident unpolarized light in the wavelength range of 450 nm to 650 nm.

[0127] In some embodiments, a circular polarizer (e.g., circular polarizer 1900 or 2000) includes: a retarder; an absorbing polarizer having an absorption band extending over the entire visible range of 400 nm to 700 nm; and a reflective polarizer disposed between the retarder and the absorbing polarizer and having a transmission axis substantially aligned with the transmission axis of the absorbing polarizer, wherein the reflective polarizer includes a plurality of alternating polymer interference layers and has a reflection band and at least one transmission band in a blocking polarization state. In some embodiments, at normal incidence, at least one transmission band has a total width of at least 150 nm in the visible range. For example, at least one transmission band may extend from 400 nm to λ1S and from λ1L to 700 nm, see Figure 6 , where λ1S–400nm+700nm-λ1L is at least 150nm. In some embodiments, at normal incidence, the reflection band 651 has a long wavelength band edge wavelength λ1L in the range of 440nm or 460nm to 550nm or 520nm and a short wavelength band edge wavelength λ1S less than 420nm or less than 410nm or less than 400nm. In some embodiments, at normal incidence, the reflection band 651 has a long wavelength band edge wavelength λ1L of about 500nm (e.g., within 5% or 500nm) and a short wavelength band edge wavelength λ1L less than 420nm or less than 410nm or less than 400nm. In some embodiments, at normal incidence, the reflection band 651 extends at least from 440nm to 480nm, and at least one transmission band extends at least from 530nm to 680nm. In some embodiments, at normal incidence, the reflection band 651 extends from at least 520nm to 590nm, and at least one transmission band extends from at least 400nm to 490nm and at least from 620nm to 700nm. In some embodiments, at normal incidence, the reflection band 651 extends from at least 600nm to 660nm, and at least one transmission band extends from at least 400nm to 560nm.

[0128] In some embodiments, the circular polarizer is adapted to recycle primarily blue wavelengths, and thus the reflective polarizer has a reflection band in the blue (e.g., reflection band 651 can have a long wavelength band edge wavelength λ1L in the range of 440 nm to 520 nm and a short wavelength band edge wavelength λ1S less than 420 nm). Recycling in the blue can be advantageous because blue emitters of OLED devices are typically less efficient and / or have shorter lifetimes than other emitters, and recycling primarily only in the blue reduces the overall ambient light reflection level compared to recycling across the entire visible spectrum using a reflective polarizer, for example.

[0129] Fig.2121 is a schematic depiction of a transmission axis 2173 of a reflective polarizer and a transmission axis 2174 of a linear absorptive polarizer. An angle θ between the transmission axis 2173 and the transmission axis 2174 is depicted. The transmission axis 2173 may be described as being substantially aligned with the transmission axis 2174 if the angle θ does not exceed 20 degrees. In some embodiments, the angle θ is less than 10 degrees or less than 5 degrees. The fast axis 2176 of the retarder is also depicted. The fast axis 2176 forms an oblique angle with the transmission axis 2173 of the reflective polarizer. In some embodiments, the bevel In the range of 30 to 60 degrees or in the range of 40 to 50 degrees. In some embodiments, is about 45 degrees (e.g., in the range of 42 or 43 degrees to 47 or 48 degrees). In some embodiments, the retarder includes a plurality of retarder layers. For example, in some embodiments, a half-wave retarder layer may be combined with a quarter-wave retarder layer to provide a retarder. For example, a combination or retarder layers may be used to provide an achromatic retarder. The fast axes of the half-wave retarder layer and the quarter-wave retarder layer may be oriented at different angles relative to the transmission axis 2173. For example, the fast axis of the half-wave retarder layer may be about 75 degrees to the transmission axis 2173, and the fast axis of the quarter-wave retarder layer may be about 45 degrees to the transmission axis 2173.

[0130] The following is a list of exemplary embodiments of the present specification.

[0131] Embodiment 1 is a display comprising: a display panel, the display panel comprising a plurality of pixels, each pixel comprising a plurality of sub-pixels; a reflective polarizer, the reflective polarizer being arranged to receive light output from the display panel, the reflective polarizer having a first reflective band,

[0132] Wherein under normal incidence, the first reflection band has a long wavelength band edge wavelength between peak emission wavelengths of two sub-pixels in the plurality of sub-pixels.

[0133] Embodiment 2 is a display according to embodiment 1, wherein at an incident angle of 45 degrees, the first reflection band has a long wavelength band edge wavelength that is smaller than a peak emission wavelength of each of the two sub-pixels.

[0134] Embodiment 3 is a display according to embodiment 1 or 2, wherein the two sub-pixels include a green sub-pixel and a red sub-pixel.

[0135] Embodiment 4 is a display according to embodiment 1 or 2, wherein the two sub-pixels include a blue sub-pixel and a green sub-pixel.

[0136] Embodiment 5 is a display according to any one of embodiments 1 to 4, wherein the plurality of sub-pixels includes at least 3 sub-pixels.

[0137] Embodiment 6 is a display according to any one of embodiments 1 to 5, wherein the plurality of sub-pixels includes at least 4 sub-pixels.

[0138] Embodiment 7 is a display according to any one of embodiments 1 to 6, wherein the plurality of pixels include red sub-pixels, green sub-pixels, and blue sub-pixels.

[0139] Embodiment 8 is a display according to embodiment 7, wherein at normal incidence, the long wavelength band edge wavelength of the first reflection band is between the peak emission wavelengths of the blue sub-pixel and the green sub-pixel.

[0140] Embodiment 9 is a display according to embodiment 7, wherein at normal incidence, the long wavelength band edge wavelength of the first reflection band is between the peak emission wavelengths of the green sub-pixel and the red sub-pixel.

[0141] Embodiment 10 is a display according to embodiment 9, wherein the reflective polarizer has a second reflection band, and wherein at normal incidence, the second reflection band has a long wavelength band edge wavelength between the peak emission wavelengths of the blue sub-pixel and the green sub-pixel.

[0142] Embodiment 11 is a display according to any one of embodiments 7 to 10, wherein the reflective polarizer has a third reflection band, wherein at normal incidence, the third reflection band has a short wavelength band edge wavelength that is larger than the long wavelength band edge wavelength of the first reflection band and smaller than the peak emission wavelength of the red sub-pixel.

[0143] Embodiment 12 is a display according to any one of embodiments 1 to 11, further comprising a diffuser disposed between the reflective polarizer and the display panel.

[0144] Embodiment 13 is a display according to any one of embodiments 1 to 12, wherein the plurality of pixels include red sub-pixels, green sub-pixels, blue sub-pixels, and white sub-pixels.

[0145] Embodiment 14 is a display according to any one of embodiments 1 to 13, wherein each pixel further includes a black matrix adjacent to the plurality of sub-pixels.

[0146] Embodiment 15 is a display according to any one of embodiments 1 to 14, wherein the reflective polarizer has a thickness in the range of 10 microns to 80 microns.

[0147] Embodiment 16 is a display according to any one of embodiments 1 to 15, wherein the reflective polarizer comprises a plurality of alternating polymer interference layers, the plurality of alternating polymer interference layers comprising alternating first polymer layers and second polymer layers, the first polymer layers being substantially uniaxially oriented.

[0148] Embodiment 17 is a display according to any one of embodiments 1 to 16, wherein the circular polarizer includes a reflective polarizer disposed between the absorbing polarizer and the retarder.

[0149] Embodiment 18 is a display, the display comprising:

[0150] A display panel, the display panel comprising a plurality of pixels, each pixel comprising a first sub-pixel, a second sub-pixel and a third sub-pixel, the first sub-pixel having a first peak emission wavelength, the second sub-pixel having a second peak emission wavelength smaller than the first peak emission wavelength, and the third sub-pixel having a third peak emission wavelength larger than the first peak emission wavelength; a circular polarizer, the circular polarizer being arranged on the display panel, the circular polarizer comprising: a retarder, the retarder facing the display panel; an absorptive polarizer, the absorptive polarizer facing away from the display panel; and a reflective polarizer, the reflective polarizer being arranged between the retarder and the absorptive polarizer, the reflective polarizer having a substantially non-overlapping first reflection band, a second reflection band and a third reflection band, wherein under normal incidence, the first reflection band comprises the first peak emission wavelength, the second reflection band comprises the second peak emission wavelength, and the third reflection band comprises the third peak emission wavelength.

[0151] Embodiment 19 is a display according to embodiment 18, wherein the reflective polarizer includes a first plurality of alternating interference layers, a second plurality of alternating interference layers, and a third plurality of alternating interference layers that do not intersect each other, the first plurality of alternating interference layers providing a first reflection band, the second plurality of alternating interference layers providing a second reflection band, and the third plurality of alternating interference layers providing a third reflection band.

[0152] Embodiment 20 is a display according to embodiment 19, wherein the first plurality of alternating interference layers is disposed closer to the display panel than the first plurality of alternating interference layers and the third plurality of alternating interference layers.

[0153] Embodiment 21 is a display according to any one of embodiments 18 to 20, wherein each of the first reflection band, the second reflection band, and the third reflection band is an original reflection band.

[0154] Embodiment 22 is a display according to embodiment 18, wherein the reflective polarizer includes a first plurality of alternating interference layers and a second plurality of alternating interference layers that do not intersect, the first plurality of alternating interference layers providing a first reflection band, the second plurality of alternating interference layers providing a second reflection band and a third reflection band, the first reflection band and the third reflection band are original reflection bands, and the second reflection band is a second-order harmonic of the third reflection band.

[0155] Embodiment 23 is a display according to embodiment 22, wherein the first plurality of alternating interference layers are disposed closer to the display panel than the second plurality of alternating interference layers.

[0156] Embodiment 24 is a display according to any one of embodiments 18 to 23, wherein each pixel further includes a fourth subpixel.

[0157] Embodiment 25 is a display according to embodiment 24, wherein the first subpixel is a green subpixel, the second subpixel is a blue subpixel, the third subpixel is a red subpixel, and the fourth subpixel is a white subpixel.

[0158] Embodiment 26 is a display according to any one of Embodiment 11 or Embodiments 18 to 25, wherein at normal incidence, the third reflection band has a long wavelength band edge wavelength in the range of 700 nm to 2500 nm.

[0159] Embodiment 27 is a display according to any one of Embodiment 11 or Embodiments 18 to 25, wherein at normal incidence, the third reflection band has a long wavelength band edge wavelength in the range of 750 nm to 900 nm.

[0160] Embodiment 28 is a display according to any one of embodiments 1 to 27, wherein the display panel includes a color filter.

[0161] Embodiment 29 is a display according to embodiment 28, wherein the distance between the reflective polarizer and the multiple pixels does not exceed 1.2 times the average center-to-center distance between the white sub-pixels in the pixel and the green sub-pixels in the pixel.

[0162] Embodiment 30 is a display according to embodiment 28, wherein the distance between the reflective polarizer and the multiple pixels is in the range of 0.8 times to 1.2 times the average center-to-center distance between the white sub-pixels in the pixel and the green sub-pixels in the pixel.

[0163] Embodiment 31 is a display according to embodiment 28, wherein the distance between the reflective polarizer and the multiple pixels does not exceed 0.6 times the average center-to-center distance between the white sub-pixels in the pixel and the green sub-pixels in the pixel.

[0164] Embodiment 32 is a display according to any one of embodiments 1 to 27, wherein each pixel includes a red sub-pixel including a red emitting material, a green sub-pixel including a green emitting material, and a blue sub-pixel including a blue emitting material.

[0165] Embodiment 33 is a display according to embodiment 32, wherein the distance between the reflective polarizer and the plurality of pixels is no more than 1.2 times the average center-to-center distance between adjacent sub-pixels.

[0166] Embodiment 34 is a display according to embodiment 32, wherein the distance between the reflective polarizer and the plurality of pixels is in a range of 0.8 to 1.2 times the average center-to-center distance between adjacent sub-pixels.

[0167] Embodiment 35 is a display according to embodiment 32, wherein the distance between the reflective polarizer and the plurality of pixels does not exceed 0.6 times the average center-to-center distance between adjacent sub-pixels.

[0168] Embodiment 36 is a display according to any one of embodiments 1 to 35, wherein the display panel includes an organic light emitting diode display panel.

[0169] Embodiment 37 is a circular polarizer, comprising:

[0170] Delay device;

[0171] an absorbing polarizer; and

[0172] a reflective polarizer disposed between the retarder and the absorbing polarizer and having a pass axis substantially aligned with a pass axis of the absorbing polarizer, the reflective polarizer comprising a plurality of alternating polymeric interference layers, the reflective polarizer having substantially non-overlapping first, second, and third reflection bands,

[0173] Where at normal incidence:

[0174] The first reflection band has a short wavelength band edge wavelength and a long wavelength band edge wavelength;

[0175] The second reflection band has a long wavelength band edge wavelength in the range of 440 nm to 500 nm, the short wavelength band edge wavelength of the first reflection band being at least 10 nm greater than the long wavelength band edge wavelength of the second reflection band; and

[0176] The third reflection band has a short-wavelength band edge wavelength in the range of 580 nm to 640 nm, the short-wavelength band edge wavelength of the third reflection band being at least 10 nm greater than the long-wavelength band edge wavelength of the first reflection band.

[0177] Embodiment 38 is a circular polarizer according to embodiment 37, wherein under normal incidence, the first reflection band has a short wavelength band edge wavelength in the range of 480nm to 510nm and has a long wavelength band edge wavelength in the range of 550nm to 570nm.

[0178] Embodiment 39 is a circular polarizer according to embodiment 37 or 38, wherein at normal incidence, the first reflection band has a bandwidth not exceeding 80 nm.

[0179] Embodiment 40 is a circular polarizer according to any one of embodiments 37 to 39, wherein the absorbing polarizer has an average transmittance in the range of 40% to 60% for normally incident unpolarized light in the wavelength range of 450nm to 650nm.

[0180] Embodiment 41 is a circular polarizer according to any one of embodiments 37 to 39, wherein the absorbing polarizer has an average transmittance in the range of 44% to 60% for normally incident non-polarized light in the wavelength range of 450nm to 650nm.

[0181] Embodiment 42 is a circular polarizer according to any one of embodiments 37 to 41, wherein the reflective polarizer has a thickness in the range of 10 microns to 80 microns.

[0182] Embodiment 43 is a circular polarizer according to any one of embodiments 37 to 42, having a thickness in the range of 30 microns to 500 microns.

[0183] Embodiment 44 is a circular polarizer according to any one of embodiments 37 to 43, wherein the plurality of alternating polymer interference layers comprises alternating first polymer layers and second polymer layers, the first polymer layers being substantially uniaxially oriented.

[0184] Embodiment 45 is a circular polarizer according to any one of embodiments 37 to 44, wherein the plurality of alternating polymer interference layers include an outermost first interference layer and a second interference layer, and each layer disposed between the outermost first interference layer and the second interference layer in the reflective polarizer has a thickness of less than 1 micron.

[0185] Embodiment 46 is a circular polarizer according to embodiment 45, wherein the multiple alternating polymer interference layers include a first plurality of alternating interference layers, a second plurality of alternating interference layers, and a third plurality of alternating interference layers that do not intersect each other, the first plurality of alternating interference layers provide a first reflection band, the second plurality of alternating interference layers provide a second reflection band, and the third plurality of alternating interference layers provide a third reflection band.

[0186] Embodiment 47 is a circular polarizer according to embodiment 46, wherein the first plurality of alternating interference layers includes an outermost first interference layer, the outermost first interference layer facing the retarder.

[0187] Embodiment 48 is a display comprising:

[0188] A display panel comprising a plurality of pixels, each pixel comprising at least a first sub-pixel, a second sub-pixel and a third sub-pixel, the first sub-pixel having a first peak emission wavelength, the second sub-pixel having a second peak emission wavelength smaller than the first peak emission wavelength, and the third sub-pixel having a third peak emission wavelength larger than the first peak emission wavelength; a circular polarizer according to any one of embodiments 37 to 47, the circular polarizer being disposed on the display panel, the circular polarizer having a delay device facing the display panel, wherein under normal incidence, the first reflection band includes the first peak emission wavelength, the second reflection band includes the second peak emission wavelength, and the third reflection band includes the third peak emission wavelength.

[0189] Embodiment 49 is a reflective polarizer comprising a plurality of alternating polymer interference layers, the plurality of alternating polymer interference layers having substantially non-overlapping first, second, and third reflection bands, each of the first, second, and third reflection bands being a first-order harmonic reflection band, the plurality of alternating polymer interference layers comprising an outermost first interference layer and a second interference layer, each layer disposed between the outermost first and second interference layers in the reflective polarizer having a thickness of less than 1 micron,

[0190] Where at normal incidence:

[0191] The first reflection band has a short wavelength band edge wavelength and a long wavelength band edge wavelength;

[0192] The second reflection band has a long wavelength band edge wavelength in the range of 440 nm to 500 nm, the short wavelength band edge wavelength of the first reflection band being at least 10 nm greater than the long wavelength band edge wavelength of the second reflection band; and

[0193] The third reflection band has a short-wavelength band edge wavelength in the range of 580 nm to 640 nm, the short-wavelength band edge wavelength of the third reflection band being at least 10 nm greater than the long-wavelength band edge wavelength of the first reflection band.

[0194] Embodiment 50 is a reflective polarizer according to embodiment 49, wherein the multiple alternating polymer interference layers include a first plurality of alternating interference layers, a second plurality of alternating interference layers and a third plurality of alternating interference layers that do not intersect each other, the first plurality of alternating interference layers providing a first reflection band, the second plurality of alternating interference layers providing a second reflection band, and the third plurality of alternating interference layers providing a third reflection band.

[0195] Embodiment 51 is a reflective polarizer according to embodiment 50, wherein the first plurality of alternating interference layers includes an outermost first interference layer.

[0196] Embodiment 52 is a reflective polarizer according to any one of embodiments 49 to 51, wherein each layer disposed between the outermost first interference layer and the second interference layer in the reflective polarizer has a thickness of less than 500 nm.

[0197] Embodiment 53 is a reflective polarizer according to any one of embodiments 49 to 52, wherein at normal incidence, the first reflection band has a short wavelength band edge wavelength in the range of 480nm to 510nm and has a long wavelength band edge wavelength in the range of 550nm to 570nm.

[0198] Embodiment 54 is a reflective polarizer according to any one of embodiments 49 to 53, wherein at normal incidence, the first reflection band has a bandwidth not exceeding 80 nm.

[0199] Embodiment 55 is a reflective polarizer according to any one of embodiments 49 to 54, which has a thickness in the range of 10 microns to 80 microns.

[0200] Embodiment 56 is a reflective polarizer according to any one of embodiments 49 to 55, wherein the plurality of alternating polymer interference layers comprises alternating first polymer layers and second polymer layers, the first polymer layers being substantially uniaxially oriented.

[0201] Embodiment 57 is a display according to any previous embodiment for a display, wherein the reflective polarizer is a reflective polarizer according to any one of embodiments 49 to 56.

[0202] Embodiment 58 is a circular polarizer comprising:

[0203] Delay device;

[0204] an absorbing polarizer; and

[0205] According to the reflective polarizer described in any one of embodiments 49 to 56, the reflective polarizer is arranged between the retarder and the absorptive polarizer.

[0206] Embodiment 59 is a circular polarizer according to embodiment 58, which is also characterized according to any one of embodiments 37 to 47.

[0207] Embodiment 60 is a display according to any previous embodiment for a display, the display comprising a circular polarizer, wherein the circular polarizer is a circular polarizer according to any one of embodiments 37 to 47 or embodiments 58 to 59.

[0208] Embodiment 61 is a display comprising: a display panel comprising a plurality of pixels, each pixel comprising at least a first sub-pixel, a second sub-pixel and a third sub-pixel, the first sub-pixel having a first peak emission wavelength, the second sub-pixel having a second peak emission wavelength smaller than the first peak emission wavelength, and the third sub-pixel having a third peak emission wavelength larger than the first peak emission wavelength; a circular polarizer according to embodiment 58 or 59, the circular polarizer being disposed on the display panel, the circular polarizer having a delay device facing the display panel, wherein under normal incidence, the first reflection band comprises the first peak emission wavelength, the second reflection band comprises the second peak emission wavelength, and the third reflection band comprises the third peak emission wavelength.

[0209] Embodiment 62 is a display comprising:

[0210] a display panel including a plurality of pixels, each pixel including a plurality of sub-pixels; a reflective polarizer arranged to receive the light output of the display panel, the reflective polarizer having a first reflective band,

[0211] Wherein under normal incidence, the first reflection band reflects at least 60% of the first light, the first light has a light-blocking polarization state and a wavelength distribution of the emission spectrum of the first sub-pixel among the multiple sub-pixels, and under an incident angle of 45 degrees, the first reflection band transmits at least 60% of the first light.

[0212] Embodiment 63 is a display according to embodiment 62, wherein at normal incidence, the first reflection band has a long wavelength band edge wavelength greater than the peak emission wavelength of the first subpixel.

[0213] Embodiment 64 is a display according to embodiment 62 or 63, wherein the reflective polarizer has a second reflection band that is substantially non-overlapping with the first reflection band, and wherein at normal incidence, the second reflection band reflects at least 60% of a second light having a light-blocking polarization state and a wavelength distribution of an emission spectrum of a second sub-pixel in the plurality of sub-pixels, and at an incident angle of 45 degrees, the second reflection band transmits at least 60% of the second light.

[0214] Embodiment 65 is a display according to embodiment 64, wherein the reflective polarizer has a third reflection band that is substantially non-overlapping with the first reflection band and substantially non-overlapping with the second reflection band, and wherein at normal incidence, the third reflection band reflects at least 60% of a third light, the third light having a light-blocking polarization state and a wavelength distribution of an emission spectrum of a third sub-pixel among the plurality of sub-pixels, and wherein at an incident angle of 45 degrees, the third reflection band transmits at least 60% of the third light.

[0215] Embodiment 66 is a display according to embodiment 65, wherein the first sub-pixel is a green sub-pixel, the second sub-pixel is a blue sub-pixel, and the third sub-pixel is a red sub-pixel.

[0216] Embodiment 67 is a display according to embodiment 66, wherein the plurality of sub-pixels further includes a fourth sub-pixel.

[0217] Embodiment 68 is a display according to embodiment 67, wherein the fourth subpixel is a white subpixel.

[0218] Embodiment 69 is a display according to any one of embodiments 62 to 68, which is also characterized according to any one of embodiments 1 to 36.

[0219] Embodiment 70 is a display according to any one of embodiments 62 to 68, wherein the circular polarizer includes a reflective polarizer disposed between the retarder and the absorbing polarizer.

[0220] Embodiment 71 is a circular polarizer comprising:

[0221] Delay device;

[0222] an absorbing polarizer having an absorption band extending across the visible range of 400 nm to 700 nm; and

[0223] A reflective polarizer disposed between the retarder and the absorbing polarizer and having a transmission axis substantially aligned with the transmission axis of the absorbing polarizer, the reflective polarizer comprising a plurality of alternating polymer interference layers, the reflective polarizer having a reflection band and at least one transmission band in a block polarization state, wherein at normal incidence, the at least one transmission band has a total width of at least 150 nm in the visible range.

[0224] Embodiment 72 is a circular polarizer according to embodiment 71, wherein under normal incidence, the reflection band has a long wavelength band edge wavelength in the range of 440nm to 550nm and a short wavelength band edge wavelength less than 420nm.

[0225] Embodiment 73 is a circular polarizer according to embodiment 71, wherein under normal incidence, the reflection band has a long wavelength band edge wavelength in the range of 460nm to 520nm and a short wavelength band edge wavelength less than 410nm.

[0226] Embodiment 74 is a circular polarizer according to embodiment 71, wherein at normal incidence, the reflection band has a long wavelength band edge wavelength of approximately 500 nm and a short wavelength band edge wavelength of less than 410 nm.

[0227] Embodiment 75 is a circular polarizer according to embodiment 71, wherein at normal incidence, the reflection band extends from at least 440nm to 480nm, and at least one transmission band extends from at least 530nm to 680nm.

[0228] Embodiment 76 is a circular polarizer according to embodiment 71, wherein at normal incidence, the reflection band extends from at least 520nm to 590nm, and at least one transmission band extends from at least 400nm to 490nm and at least from 620nm to 700nm.

[0229] Embodiment 77 is a circular polarizer according to embodiment 71, wherein at normal incidence, the reflection band extends from at least 600nm to 660nm, and at least one transmission band extends from at least 400nm to 560nm.

[0230] Embodiment 78 is a display according to embodiment 70, wherein the circular polarizer is a circular polarizer according to any one of embodiments 37 to 47 or embodiments 71 to 67.

[0231] Embodiment 79 is a display according to any one of embodiments 62 to 71, wherein the reflective polarizer is a reflective polarizer according to any one of embodiments 49 to 56.

[0232] Example

[0233] Example 1: Reflective polarizer with 3 reflection bands, f-ratio 0.2

[0234] A reflective polarizer with three non-overlapping reflection bands was prepared as follows. A single multilayer optical packet was coextruded. The packet included 275 alternating layers of 90 / 10coPEN and low refractive index isotropic layers. 90 / 10coPEN is a polymer composed of 90% polyethylene naphthalate (PEN) and 10% polyethylene terephthalate (PET). The isotropic layer is made of a blend of polycarbonate and copolyester (PC:coPET) as described in WO2015035030 such that the refractive index is about 1.57 and the layer remains substantially isotropic when uniaxially oriented. The PC:coPET molar ratio is about 42.5 mol% PC and 57.5 mol% coPET. The isotropic layer has a Tg of 105 degrees Celsius. This isotropic material was chosen so that after stretching, its refractive index in the two non-stretch directions remained substantially matched to that of the birefringent material in the non-stretch direction, while in the stretch direction there was a significant mismatch in refractive index between the birefringent and non-birefringent layers. The 90 / 10 PEN and PC:coPET polymers were fed from separate extruders to a multilayer coextrusion feed block at a ratio of 15% and 84% of the total flow of 90 / 10 PEN and PC:coPET, respectively, with a target f-ratio of 0.20. The material was assembled into groups of 275 alternating optical layers, plus a thicker protective boundary layer of PC:coPET on each side, for a total of 277 layers. The multilayer melt was then cast through a film die onto a chill roll where it was quenched in the conventional manner for polyester films. The cast web is then stretched in a parabolic tenter similar to that described in invited paper 45.1, "Advanced Polarizer Film for Improved Performance of Liquid Crystal Displays," by Denker et al., presented at the Society for Information Display (SID) International Conference, June 4-9, 2006, in San Francisco, California.

[0235] The film has Fig.28 Layer thickness distribution of the alternating interference layers depicted in . The film utilized an f-ratio of about 0.2 and had a total thickness of about 25 microns, including a 3 micron thickness of the protective boundary layer on the opposite side of the alternating interference layers.

[0236] Example 2: Reflective polarizer with 2 reflection bands, f-ratio 0.24

[0237] A reflective polarizer with two non-overlapping reflective bands was made as follows. A single multilayer optical packet was coextruded. The packet included 275 alternating layers of 90 / 10 coPEN and low refractive index isotropic layers. 90 / 10 coPEN is a polymer composed of 90% polyethylene naphthalate (PEN) and 10% polyethylene terephthalate (PET). The isotropic layers were made of a blend of polycarbonate and copolyester (PC:coPET) as described in WO2015035030 such that the refractive index is about 1.57 and the layers remain substantially isotropic when uniaxially oriented. The PC:coPET molar ratio is about 42.5 mol% PC and 57.5 mol% coPET. The isotropic layers have a Tg of 105 degrees Celsius. This isotropic material was chosen so that after stretching, its refractive index in the two non-stretched directions remained substantially matched to that of the birefringent material in the non-stretched direction, while in the stretch direction there was a significant mismatch in refractive index between the birefringent and non-birefringent layers. The 90 / 10 PEN and PC:coPET polymers were fed from separate extruders to a multilayer coextrusion feed block at a ratio of 18% and 82% of the total flow of 90 / 10 PEN and PC:coPET, respectively, with a target f-ratio of 0.24. The material was assembled into groups of 275 alternating optical layers, plus a thicker protective boundary layer of PC:coPET on each side, for a total of 277 layers. The multilayer melt was then cast through a film die onto a chill roll where it was quenched in the conventional manner for polyester films. The cast web is then stretched in a parabolic tenter similar to that described in invited paper 45.1, "Advanced Polarizer Film for Improved Performance of Liquid Crystal Displays," by Denker et al., presented at the Society for Information Display (SID) International Conference, June 4-9, 2006, in San Francisco, California.

[0238] The film has Fig.29 Layer thickness distribution of the alternating interference layers depicted in . The film utilized an f-ratio of about 0.24 and had a total thickness of about 24 microns, including a 3 micron thickness of the protective boundary layer on the opposite side of the alternating interference layers.

[0239] Example 3: Reflective polarizer with 1 reflection band, f-ratio 0.5

[0240] A reflective polarizer with one reflection band was made as follows. A single multilayer optical packet was coextruded. The packet included 275 alternating layers of 90 / 10 coPEN and low refractive index isotropic layers. 90 / 10 coPEN is a polymer composed of 90% polyethylene naphthalate (PEN) and 10% polyethylene terephthalate (PET). The isotropic layers were made of a blend of polycarbonate and copolyester (PC:coPET) as described in WO2015035030 such that the refractive index is about 1.57 and the layers remain substantially isotropic when uniaxially oriented. The PC:coPET molar ratio is about 42.5 mol% PC and 57.5 mol% coPET. The isotropic layers had a Tg of 105 degrees Celsius. This isotropic material was chosen so that after stretching, its refractive index in the two non-stretched directions remained substantially matched to that of the birefringent material in the non-stretched direction, while in the stretch direction there was a significant mismatch in refractive index between the birefringent and non-birefringent layers. The 90 / 10 PEN and PC:coPET polymers were fed from separate extruders to a multilayer coextrusion feed block at a ratio of 42% and 58% of the total flow of 90 / 10 PEN and PC:coPET, respectively, with a target f-ratio of 0.50. The material was assembled into groups of 275 alternating optical layers, plus a thicker protective boundary layer of PC:coPET on each side, for a total of 277 layers. The multilayer melt was then cast through a film die onto a chill roll where it was quenched in the conventional manner for polyester films. The cast web is then stretched in a parabolic tenter similar to that described in invited paper 45.1, "Advanced Polarizer Film for Improved Performance of Liquid Crystal Displays," by Denker et al., presented at the Society for Information Display (SID) International Conference, June 4-9, 2006, in San Francisco, California.

[0241] The film has Fig.30 Layer thickness distribution of the alternating interference layers depicted in . The film utilized an f-ratio of about 0.50 and had a total thickness of about 21 microns, including the thickness of the 3 microns protective boundary layer on the opposite side of the alternating interference layers.

[0242] Comparative Example 1 (CE-1) – APF-V3

[0243] A commercial multilayer optical film available as APF-V3 (3M Company, St. Paul, MN) was used for comparison with Examples 1-3.

[0244] Circular polarizers were prepared and incorporated into televisions for testing :

[0245] Circular polarizers were prepared for each of Examples 1 to 3 and the CE-1 multilayer optical film. In each case, an absorbing polarizer (AP) Model 5618H (from Sanritz, Toyama, Japan) was laminated to the exemplary film with the block axis of the exemplary multilayer optical film and the block axis of the absorbing polarizer substantially aligned. On the side opposite the exemplary multilayer optical film, a quarter wave plate (QWP) with the trade name APQW92-004-PC-140NMHE (from American Polarizers, Inc., Reading, PA) was laminated using 8171 optically clear adhesive (available from 3M Company, St. Paul, Minnesota). The QWP optical axis was approximately 45 degrees relative to the optical device axis of the two polarizers.

[0246] For in-situ testing of each example, the circular polarizer produced by this process was laminated to an LG OLED55B7A TV from which the original circular polarizer had been removed. Emission luminance and color were measured via a PR-705 spectrophotometer from Photo Research. Reflectivity was measured via a Lambda 900 spectrometer from Perkin-Elmer. A Keyence VHX-600 digital microscope with a Z20-200X lens was used to image the pixels at various tilt angles and determine the grayscale values ​​that provide a measure of the luminance distribution.

[0247] Test Results :

[0248] The reflectance spectrum was measured for each example. Fig.31 The measured spectra of the Example 1 film in the light blocking state and the light transmitting state are shown. Fig.32 The measured spectrum of the light blocking state of the Example 1 film is shown along with the OLED emission peak. Fig.33 The measured spectra of the Example 2 film in the blocking state and the light transmitting state are shown. Fig.34 The measured spectrum of the light blocking state of the Example 3 film is shown along with the OLED emission peak.

[0249] For each of Comparative Example (CE-1) and Examples 1 to 3, circular polarizers were prepared as described above and subsequently incorporated into commercial OLED televisions to replace existing circular polarizers. A cross section of the image was taken horizontally across 2 emitting pixels, and then a ghost image of those two pixels was taken as a measure of the intensity of the undesirable ghosting. A graph of the collected images helps to illustrate the test images; the distributions from these test images were extracted for the tabulated values ​​for comparison. FIG. 35A to FIG. 35E are illustrative pixel and ghost images showing, respectively, Comparative Example 1 film (CE-1) used in a circular polarizer and tested on an OLED TV at viewing angles of 15 degrees, 30 degrees, 40 degrees, 55 degrees, and 60 degrees. FIG. 36A to FIG. 36E The results are shown in Comparative Example 1 (CE-1). FIG. 35A to FIG. 35E The extracted luminance distribution is determined by the gray value measured in the image. The x position refers to the x coordinate across the width of the pixel (e.g., corresponding to Figure 2 x' coordinate of the FIG. 37A to FIG. 37E are images showing illustrative pixels and ghost images, respectively, of the Example 1 film used in a circular polarizer and tested on an OLED TV at viewing angles of 20, 25, 40, 45, and 60 degrees. FIG. 38A to FIG. 38E The results for Example 1 are shown respectively. FIG. 37A to FIG. 37E The extracted luminance distribution of the image. FIG. 39A to FIG. 39B Shown are the pixel and ghost images and corresponding extracted distributions, respectively, of the Example 2 film used in a circular polarizer and tested on an OLED TV at a viewing angle of 20 degrees. FIG. 39A to FIG. 39B Shown are the pixel and ghost images and corresponding extracted distributions, respectively, of the Example 2 film used in a circular polarizer and tested on an OLED TV at a viewing angle of 40 degrees. FIG. 41A to FIG. 41B Shown are the pixel and ghost images and corresponding extracted distributions, respectively, of the Example 3 film used in a circular polarizer and tested on an OLED TV at a viewing angle of 20 degrees. FIG. 42A to FIG. 42B Shown are the pixel and ghost images and corresponding extracted distributions, respectively, of the Example 3 film used in a circular polarizer and tested on an OLED TV at a viewing angle of 20 degrees.

[0250] Fig.43 The luminance of each example is shown relative to the cross section extracted at the viewing angle (0 degrees). The luminance of each example is normalized by dividing the measured luminance by the unmodified (original) television (TV) luminance. With this normalization, the gain at each angle is calculated relative to the original TV output. Fig.44 This calculated gain is shown as a function of viewing angle.

[0251] exist Fig.44In the , the variation with viewing angle appears as a series of peaks and valleys. These variations in gain (peak to valley) are a measure of the intensity of ghost imaging. This difference in luminance gain (from peak to valley) is defined as the "Eldim ghosting metric" and is reported in Table 1 using the measured luminance. The ghost / pixel ratios determined by the Keyence microscope are reported in Table 2.

[0252] Table 1: Luminance and Eldim ghosting metrics

[0253]

[0254] Table 2: Keyence ghosting / pixel ratios

[0255]

[0256] Example 4: Optical Modeling of Reflective Polarizers in Displays

[0257] The Berreman algorithm was used using a 4×4 matrix approach for a reflective polarizer similar to Example 1 and having Fig. 22 A reflective polarizer with the thickness profile shown in Figure 1 was modeled to determine the spectra of constructive and destructive interference generated from the layer interfaces in the reflective polarizer. The refractive index of the isotropic layer in each direction was measured to be 1.5792 at a wavelength of 550 nm and 1.5705 at a wavelength of 633 nm. The refractive index of the birefringent layer in the blocking direction was measured to be 1.8372 at 550 nm and 1.8120 at 633 nm. The refractive index of the birefringent layer in the transmitting direction was taken to be 1.5755 at 550 nm and 1.5652 at 633 nm. The refractive index of the birefringent layer in the thickness direction was taken to be 1.5690 at 550 nm and 1.5587 at 633 nm.

[0258] exist Fig.23 Calculated reflectivity versus wavelength at normal incidence in the blocking state is shown superimposed on the emission spectra of the blue, green, red, and white subpixels of an LG model 65E6 OLED TV. Three distinct and substantially non-overlapping reflection bands can be seen in the reflectivity spectrum.

[0259] A circular polarizer including the reflective polarizer is modeled at a distance D of 500 microns from the display panel (the distance between the outermost interference layer and the color filter). The circular polarizer includes the reflective polarizer between the absorptive polarizer and the quarter-wave retarder, wherein the pass axes of the reflective polarizer and the absorptive polarizer are aligned, and the fast axis of the retarder is at 45 degrees to the aligned pass axis. The photopic gain as a function of the aerial polar viewing angle is determined for each subpixel individually. FIG. 24A to FIG. 24DThe results for the red sub-pixel, green sub-pixel, blue sub-pixel and white sub-pixel are shown in FIG. Fig. 24B The peak at about 65 degrees of viewing angle in is due to the red reflection band shifting to green wavelengths at high incident angles. Similarly, Fig.24C The peak at a viewing angle of about 70 degrees is due to the green reflection band shifting to blue wavelengths at high incident angles.

[0260] Fig.25 2 is a schematic top view of a portion of a modeled display panel 2530, which depicts the distance d1 between the closest edges of the green subpixel and the white subpixel and the distance d2 between the farthest edges of the green subpixel and the white subpixel. The red subpixel (R), white subpixel (W), blue subpixel (B), and green subpixel (G) are indicated. In the modeled example, d1 is 120 microns and d2 is 270 microns. The walk-off distance d (see Figure 1 ) A green sub-pixel in the range of 120 microns to 270 microns can potentially partially reflect from a white sub-pixel. The walk-off distance range of 390 microns to 540 microns in this modeled example allows a green sub-pixel to potentially partially reflect from a green sub-pixel of an adjacent pixel. Assume that a black matrix material 2539 surrounds the sub-pixel. The black material is modeled to reduce the total reflectivity of the display panel by about 40% to about 20%.

[0261] Fig.26 is a graph of the internal incident angle θint and the external aerial viewing angle θext as a function of the spacing (referred to as the Z gap) between the reflective region reflecting green light in the reflective polarizer (RP) and the color filter (CF). Sufficiently large θint results in total internal reflection (TIR) ​​at the display-air interface. In an embodiment where the green reflective region is adjacent to the outermost surface of the reflective polarizer, the Z gap is approximately equal to the distance D between the reflective polarizer and the plurality of pixels.

[0262] exist Fig.2626 shows schematically the angle ranges at which the reflective polarizer has strong or weak reflection. The reflective polarizer has strong reflection in green wavelengths at internal incident angles in range 2666 (less than about 20 degrees); weak reflection at internal incident angles in range 2667 (between about 20 degrees and about 30 degrees), where the green reflection band has shifted to lower wavelengths; strong reflection at internal incident angles in range 2668 (between about 30 degrees and about 40 degrees), where the red reflection band has shifted to green wavelengths; and weak reflection at higher incident angles. At a Z gap of about 200 microns (roughly the center-to-center distance between the green and white sub-pixels) or at a Z gap of less than about 70 microns, the reflection due to a walk-off distance of 120 microns to 270 microns is weak, and the reflection due to a longer walk-off distance between 390 microns and 540 microns is also weak.

[0263] The ambient specular photopic reflectance was calculated to be 1.80%. In contrast, when an advanced polarizing film (APF) purchased from 3M Company (St. Paul, Minnesota) was used in the model instead of the reflective polarizer, the ambient specular photopic reflectance was calculated to be 2.90%. Therefore, replacing the APF reflective polarizer with the reflective polarizer of the present specification results in reduced ambient specular photopic reflectance. Using the reflective polarizer of Example 1 with a Z gap of approximately 200 microns also produces less ghosting than using the APF in the circular polarizer. When the reflective polarizer was removed from the circular polarizer, the ambient specular photopic reflectance was calculated to be 0.90%, but this also resulted in reduced brightness and color gamut. The color gamut was 93.1% NTSC without the reflective polarizer, 96.6% NTSC with the reflective polarizer of Example 1 in the circular polarizer, and 98.0% NTSC with the APF in the reflective polarizer. The calculated brightness gain and radiation gain for each type of sub-pixel obtained by using the reflective polarizer of Example 1 in the circular polarizer and using the APF in the circular polarizer are reported in Table 3 below. The radiation gain is determined at wavelengths near the peak emission wavelength of the sub-pixel. By definition, the brightness and radiation gain of each sub-pixel is 100% when the reflective polarizer is not included in the modeled circular polarizer.

[0264] Table 3

[0265]

[0266] All references, patents, and patent applications cited above are hereby incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or conflicts between an incorporated reference portion and the present application, the information in the foregoing description shall prevail.

[0267] Unless otherwise indicated, the description of the elements in the drawings should be understood to be equally applicable to the corresponding elements in the other drawings. Although specific embodiments have been illustrated and described herein, it will be appreciated by those skilled in the art that the specific embodiments shown and described may be replaced with a variety of alternative and / or equivalent implementations without departing from the scope of the present disclosure. The present application is intended to cover any modification or variation of the specific embodiments discussed herein. Therefore, it is expected that the present disclosure is limited only by the claims and their equivalents.

Claims

1. A display, comprising: A display panel, the display panel comprising a plurality of pixels, each pixel comprising a plurality of sub-pixels; a reflective polarizer disposed to receive the light output of the display panel, the reflective polarizer having a first reflective band, wherein at normal incidence, the first reflection band has a long wavelength band edge wavelength between a peak emission wavelength of a first sub-pixel of the plurality of sub-pixels and a peak emission wavelength of a second sub-pixel of the plurality of sub-pixels, such that the reflective polarizer reflects at least 60% of first light having a block polarization state emitted by the first sub-pixel through the first reflection band, wherein the peak emission wavelength of the second sub-pixel is greater than the peak emission wavelength of the first sub-pixel, and Wherein at an incident angle of 45 degrees, the first reflection band has a long wavelength band edge wavelength less than the peak emission wavelength of each of the first and second sub-pixels such that the reflective polarizer transmits at least 60% of the first light.

2. The display of claim 1 , wherein the plurality of pixels comprises a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and wherein at normal incidence, the long wavelength band edge wavelength of the first reflection band is between the peak emission wavelengths of the blue sub-pixel and the green sub-pixel.

3. The display of claim 1 , wherein the plurality of pixels comprises a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and wherein at normal incidence, the long wavelength band edge wavelength of the first reflection band is between the peak emission wavelengths of the green sub-pixel and the red sub-pixel.

4. The display of claim 3 wherein the reflective polarizer has a second reflection band, and wherein at normal incidence, the second reflection band has a long wavelength band edge wavelength between the peak emission wavelengths of the blue subpixel and the green subpixel.

5. The display of claim 4 wherein the reflective polarizer has a third reflection band, wherein at normal incidence, the third reflection band has a greater reflectivity than the first reflection band. The long wavelength band edge wavelength is larger than the short wavelength band edge wavelength and smaller than the peak emission wavelength of the red sub-pixel.

6. A display according to any one of claims 1 to 5, wherein a circular polariser comprises the reflective polariser, the reflective polariser being arranged between the absorbing polariser and the retarder.

7. A display, comprising: A display panel, the display panel comprising a plurality of pixels, each pixel comprising a first sub-pixel, a second sub-pixel and a third sub-pixel, the first sub-pixel having a first peak emission wavelength, the second sub-pixel having a second peak emission wavelength smaller than the first peak emission wavelength, and the third sub-pixel having a third peak emission wavelength larger than the first peak emission wavelength; a circular polarizer disposed on the display panel, the circular polarizer comprising: a retarder, the retarder facing the display panel; an absorbing polarizer, the absorbing polarizer facing away from the display panel; and a reflective polarizer, the reflective polarizer disposed between the retarder and the absorbing polarizer, the reflective polarizer having a substantially non-overlapping first reflection band, a second reflection band, and a third reflection band, wherein at normal incidence, the first reflection band includes the first peak emission wavelength, the second reflection band includes the second peak emission wavelength, and the third reflection band includes the third peak emission wavelength, Wherein under normal incidence, the reflective polarizer reflects at least 60% of the first light having the light-blocking polarization state emitted by the first subpixel through the first reflection band, and under an incident angle of 45 degrees, the reflective polarizer transmits at least 60% of the first light.

8. The display of claim 7 wherein the reflective polarizer comprises a first plurality of alternating interference layers, a second plurality of alternating interference layers, and a third plurality of alternating interference layers that do not intersect each other, the first plurality of alternating interference layers providing the first reflection band, the second plurality of alternating interference layers providing the second reflection band, and the third plurality of alternating interference layers providing the third reflection band.

9. A display, comprising: A display panel, the display panel comprising a plurality of pixels, each pixel comprising at least a first sub-pixel, a second sub-pixel and a third sub-pixel, the first sub-pixel having a first peak emission wavelength, the second sub-pixel having a second peak emission wavelength smaller than the first peak emission wavelength, and the third sub-pixel having a third peak emission wavelength larger than the first peak emission wavelength; A circular polarizer, comprising: Delay device; an absorbing polarizer; and a reflective polarizer disposed between the retarder and the absorptive polarizer and having a pass axis substantially aligned with a pass axis of the absorptive polarizer, the reflective polarizer comprising a plurality of alternating polymeric interference layers, the reflective polarizer having substantially non-overlapping first, second, and third reflection bands, Where at normal incidence: The first reflection band has a short wavelength band edge wavelength and a long wavelength band edge wavelength; The second reflection band has a long wavelength band edge wavelength in the range of 440 nm to 500 nm, the short wavelength band edge wavelength of the first reflection band being at least 10 nm greater than the long wavelength band edge wavelength of the second reflection band; and the third reflection band has a short-wavelength band edge wavelength in the range of 580 nm to 640 nm, the short-wavelength band edge wavelength of the third reflection band being at least 10 nm greater than the long-wavelength band edge wavelength of the first reflection band, wherein the circular polarizer is disposed on the display panel, and the retarder faces the display panel, wherein at normal incidence, the first reflection band includes the first peak emission wavelength, the second reflection band includes the second peak emission wavelength, and the third reflection band includes the third peak emission wavelength, and Wherein under normal incidence, the reflective polarizer reflects at least 60% of the first light having the light-blocking polarization state emitted by the first subpixel through the first reflection band, and under an incident angle of 45 degrees, the reflective polarizer transmits at least 60% of the first light.

10. The circular polarizer of claim 9, wherein at normal incidence, the first reflection band has a short wavelength band edge wavelength in the range of 480 nm to 510 nm and has a long wavelength band edge wavelength in the range of 550 nm to 570 nm.

11. A display, comprising: A display panel, the display panel comprising a plurality of pixels, each pixel comprising a plurality of sub-pixels; a reflective polarizer disposed to receive the light output of the display panel, the reflective polarizer having a first reflective band, Wherein, under normal incidence, the reflective polarizer reflects at least 60% of the first light having a light-blocking polarization state emitted by the first sub-pixel among the multiple sub-pixels through the first reflection band, and under an incident angle of 45 degrees, the reflective polarizer transmits at least 60% of the first light.

12. The display of claim 11 , wherein the reflective polarizer has a second reflective band that is substantially non-overlapping with the first reflective band, and wherein at normal incidence, the second reflective band reflects at least 60% of a second light having the block polarization state and a wavelength distribution of an emission spectrum of a second sub-pixel in the plurality of sub-pixels, and wherein at an incident angle of 45 degrees, the second reflective band transmits at least 60% of the second light.

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