WO2025215465A1

WO2025215465A1 - Display system including layer with diffractive and non-diffractive regions

Info

Publication number: WO2025215465A1
Application number: PCT/IB2025/053424
Authority: WO
Inventors: John M. DESUTTER; Stephen M. Menke
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2024-04-10
Filing date: 2025-04-01
Publication date: 2025-10-16
Anticipated expiration: 2026-10-10

Abstract

A display system includes a display region including a plurality of pixels configured to form an image thereacross for viewing by a viewer; and a light diffractive layer configured to be between the viewer and the display region. Each pixel may include first and second pluralities of subpixels. The subpixels define intra-pixel regions therebetween and the pixels define inter-pixels therebetween. The diffractive layer includes a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. The non-diffractive region substantially overlaps the subpixels and portions of the intra-pixel and inter-pixel regions. The diffractive region substantially overlaps intra-pixel and inter-pixel regions not overlapped by the light non-diffractive region. The portions of the intra-pixel and inter-pixel regions can be selected to provide desired luminance profiles of light emitted by the pixels and transmitted by the diffractive layer.

Description

DISPLAY SYSTEM INCLUDING LAYER WITH DIFFRACTIVE AND NON-DIFFRACTIVE

REGIONS

TECHNICAL FIELD

The present description relates generally to display systems.

BACKGROUND

A display system can include a micro-light emitting diode (micro-LED) display panel.

SUMMARY

In some aspects, the present description provides a display system including a display region including a plurality of pixels configured to form an image thereacross for viewing by a viewer; and a light diffractive layer configured to be between the viewer and the display region. Each pixel may include first and second pluralities of subpixels. The subpixels define intra-pixel regions therebetween and the pixels define inter-pixels therebetween. The diffractive layer includes a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. The non-diffractive region substantially overlaps the subpixels and portions of the intra-pixel and inter-pixel regions. The diffractive region substantially overlaps intra-pixel and inter-pixel regions not overlapped by the light non-diffractive region. The portions of the intra-pixel and inter-pixel regions may be selected to provide desired luminance profiles of light emitted by the pixels and transmitted by the diffractive layer.

In some aspects, the present description provides a display system including a display region including a plurality of pixels configured to form an image thereacross for viewing by a viewer; and a light diffractive layer configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region. Each pixel can include three or more subpixels. The subpixels define non-overlapping first and second intra-pixel regions therebetween for each pixel. The pixels define non-overlapping first and second inter-pixels therebetween. Each of the first and second intra-pixel regions and the first and second inter-pixel regions is devoid of any light emitting subpixel. The subpixels, the first intra-pixel regions, and the first inter-pixel regions defines a first combined region, and the second intra-pixel regions and the second inter-pixel regions define a second combined region. The light diffractive layer includes a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. The light non-diffractive and diffractive regions of the light diffractive layer are aligned, and substantially coextensive in length and width, with the respective first and second combined regions, such that for each subpixel, for a first light emission angle relative to the thickness direction of greater than about 10 degrees and a second light emission angle relative to the thickness direction of less than about -10 degrees, and for first and second planes orthogonal to one another and parallel to the thickness direction: light emitted by the subpixel in the first plane at each of the first and second emission angles is diflfractively transmitted by the light diffractive region of the light diffractive layer; and light emitted by the subpixel in the second plane at each of the first and second emission angles is non-diffractively transmitted through the light non-diffractive region of the light diffractive layer.

In some aspects, the present description provides a display system including a display region configured to form an image thereacross for viewing by a viewer and including a plurality of pixels defining a light emitting region configured to emit light and a light non-emitting region not configured to emit light; and a light diffractive layer configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region. Each pixel includes nonoverlapping first and second pluralities of subpixels, where each of the first and second pluralities includes at least three different subpixels having at least three different emission spectra. The light diffractive layer includes a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. The light diffractive region is aligned, and substantially coextensive in length and width, with a first non-emitting region of the light non-emitting region. The light non-diffractive region is aligned, and substantially coextensive in length and width, with a region including the light emitting region and a second non-emitting region of the light non-emitting region. The first and second non-emitting regions are non-overlapping regions selected from the light non-emitting region so that for each of the first plurality of subpixels and a combined plurality of subpixels including the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, where at least some of the emitted light is diffractively transmitted by the light diffractive layer, such that: in a first plane parallel to the thickness direction, the exiting light has a substantially same first normalized luminance profile as a function of light propagation angle relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees; and in a second plane parallel to the thickness direction and orthogonal to the first plane, the exiting light has a substantially same second normalized luminance profile as a function of light propagation angle relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees.

In some aspects, the present description provides a display system including a display region configured to form an image thereacross for viewing by a viewer and including a plurality of pixels defining a light emitting region configured to emit light and a light non-emitting region not configured to emit light; and a light diffractive layer configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region. Each pixel includes nonoverlapping first and second pluralities of subpixels, where each of the first and second pluralities includes at least three different subpixels having at least three different emission spectra. The light diffractive layer includes a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. The light diffractive region is aligned, and substantially coextensive in length and width, with a first non-emitting region of the light non-emiting region. The light non-diffractive region is aligned, and substantially coextensive in length and width, with a region including the light emiting region and a second non-emiting region of the light non-emiting region. The first and second non-emiting regions are non-overlapping regions selected from the light non-emiting region so that for each of the first plurality of subpixels and a combined plurality of subpixels including the first and second pluralities of subpixels, light emited by the subpixels is transmited by the light diffractive layer and exits the display system in air toward the viewer, where at least some of the emited light is diffractively transmited by the light diffractive layer, such that: in a first plane parallel to the thickness direction, the exiting light has a first luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about a second plane parallel to the thickness direction and orthogonal to the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees; and in the second plane, the exiting light has a second luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees.

These and other aspects will be apparent from the following detailed description. In no event, however, should this brief summary be construed to limit the claimable subject mater.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are schematic cross-sectional views of a portion of a display system, according to some embodiments.

FIGS. 2-4 are schematic top plan views of portions of display systems, according to some embodiments.

FIG. 5 is a schematic top plan view of a pixel, according to some embodiments.

FIG. 6 is a schematic plot of emission spectra of subpixels, according to some embodiments.

FIGS. 7A-7D shows luminance profile plots for display systems including diffractive layers with linear diffractive elements, according to some embodiments.

FIG. 8 shows luminance profile plots for a display system including a diffractive layer including a two-dimensional grating, according to some embodiments.

DETAILED DESCRIPTION

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

A display system can emit light along an axial direction towards a viewer and along off-axis directions. In some cases, it is desired that at least some of the off-axis light in at least one plane (e.g., in a vertical plane) is redirected substantially along the axial direction to increase the axial luminance and the brightness experienced by the viewer. It is often desired that the light output having the increase in axial brightness have a desired (e.g., symmetric) luminance profile as a function of light propagation angle. It has been found, according to some embodiments, that suitably patterned light diffractive layers described herein can be used to achieve improved axial brightness with a desired luminance profile. The suitably patterned light diffractive layers can include non-diffractive regions covering light emitting regions of a display and covering some portions of light non-emitting regions that are selected to produce the desired luminance profile. Luminance can be measured using standard photometric techniques where the CIE 1931 tristimulus y function may be used as the photopic luminous efficiency function for converting radiant quantities to luminous quantities.

Diffraction gratings have been used with displays for other purposes. A diffraction grating can be placed over an organic light emitting diode (OLED) display panel to correct off-axis color shift as described in U.S. Pat. No. 10,991,765 (Freier et al.), for example. Diffractive structures can be disposed on emissive regions of an OLED device within an evanescent zone of the emissive regions to improve extraction of light that would otherwise be trapped in the OLED device as described in U.S. Pat. Appl. Pub. No. 2010/0110551 (Lamansky et al.), for example. In each of these cases, a diffractive layer is placed over an entire emissive layer of the OLED device. However, when a diffraction grating is placed over an entire emissive layer with the diffraction grating selected to provide a first order diffraction of at least some of the off-axis light into the axial direction, some of the light emitted by the pixels in the axial direction will be diffracted into off-axis directions so that the axial brightness is not substantially increased by redirecting the off-axis light. Diffraction gratings have also been used over light nonemitting regions of a display to increase axial efficiency of the display as described in International App. Pub. No. WO 2024/033838 (DeSutter et al.).

According to some embodiments of the present description, a light diffractive layer can be patterned to include light diffractive regions above some portion, but not some other portion, of a light non-emitting region of the display surface but not above the light emitting regions (e.g., subpixels) and this allows at least some of the off-axis light to be diffracted into (or close to) the axial direction substantially without diffracting the emitted axial light into non-axial directions, and it has been found that the portion of the light non-emitting region covered by the light diffractive regions can be selected to give desired properties of the luminance profile of light exiting the display. In some embodiments, this can result in significant improvement in axial luminance (e.g., by at least 10, 15, 20, 25, 30, 35, 40, 45, or even 50%) compared to a comparative display system that does not include the diffractive layer and/or compared to a display system that includes a diffractive layer with diffractive structures covering the entire display panel.

A display can include pixels where each pixel includes at least two sets of subpixels for redundancy. For example, a micro-light emitting diode (micro-LED) display panel can include such redundant subpixels since it has been difficult to reliably provide micro-LEDs without defects. However, it has been found that when redundant subpixels are included, placing a light diffractive layer above the display surface with non-diffractive regions over the subpixels and with diffractive regions over interpixel regions between the pixels can result in undesired properties of the luminance profde of the emitted light. For example, as described further elsewhere herein, it has been found that light from a first set of the subpixels (e.g., primary subpixels) can have a different normalized luminance profile after being transmitted through the light diffractive layer than light from a second set of subpixels (e.g., secondary or redundant subpixels), or light from the combination of the first and second sets, due to light from a subpixel being diffractively transmitted by the light diffractive layer when emitted at a first emission angle (e.g., greater than 10 degrees from normal) in a first plane but non-diffractively transmitted when emitted at an opposite second emission angle (e.g., less than minus 10 degrees from normal). In addition, or alternatively, it has been found that this can result in an undesired asymmetry between luminance for the transmitted light emitted at the first and second emission angles. However, it has been found, according to some embodiments of the present description, that the regions of the display covered by the diffractive regions can be selected (e.g., covering some intra-pixel regions and some intra-pixel regions) such that the resulting normalized luminance distribution has a desired symmetry (e.g., symmetry under reflection about one or more planes and/or symmetry between the first subpixels and the second subpixels or the first subpixels and a combination of the first and second subpixels).

The luminance distribution can be normalized by any fixed value. For example, the normalized luminance distribution can be the luminance distribution divided by the value of the luminance distribution at 0 degrees relative to the normal or thickness direction of the display, or the normalized luminance distribution can be the luminance distribution divided by the value of a comparative luminance distribution at 0 degrees relative to the normal or thickness direction of the display, where the comparative luminance distribution is the luminance distribution of a comparative display system that has a same construction as the display system except that it does not include the light diffractive layer.

A pixel is a smallest addressable element forming a unit of an image in a display where the unit can produce the color gamut of the display. For example, a standard full (1080p) high definition display includes 1920 x 1080 pixels and a standard 4K display includes 3840 x 2160 pixels. A pixel typically includes at least three subpixels so that the pixel can produce the desired color gamut. When redundant subpixels are included, a pixel typically includes at least 6 subpixels (e.g., red, green, and blue subpixels of the first (primary) plurality of subpixels and red, green, and blue subpixels of the second (redundant) plurality of subpixels). Regions between the subpixels of a pixel may be referred to as intra-pixel regions and regions between pixels may be referred to as inter-pixel regions.

FIGS. 1A-1B are schematic cross-sectional views of a portion of a display system 100, according to some embodiments. FIGS. 2-4 are schematic top plan views of portions of display systems 100, 100', 100", according to some embodiments. The display system 100, 100', 100" includes a display region 101 including light emitting regions 110 (e.g., subpixels) and light non-emitting regions 120 (e.g., inter-pixel or intra-pixel non-emitting regions). The display system can include a (e.g., emissive) display layer 151 including the display region 101. The display system 100, 100', 100" incudes a light diffractive layer 150, 150', 150". The light diffractive layer 150 includes a linear grating in display system 100 and the light diffractive layer 150', 150" includes a two-dimensional grating in display system 100', 100". Display system 100" has a different pixel layout than display systems 100 and 100'. The pixel layout of display system 100" can alternatively be used with a linear grating such as that of light diffractive layer 150.

In some embodiments, a display system 100, 100', 100" includes a display region 101 including a plurality of pixels 105 configured to form an image 107 thereacross for viewing by a viewer 109. Each pixel can include three or more subpixels. In some embodiments, each pixel can include nonoverlapping first and second pluralities 110a and 110b of subpixels 110. Each of the first and second pluralities 110a and 110b can include at least three different subpixels having at least three different emission spectra (see, e.g., FIGS. 5-6). The subpixels 110 define non-overlapping first and second intra-pixel regions 111 and 112 therebetween for each pixel. The pixels define non-overlapping first and second inter-pixel regions 121 and 122 therebetween. Each of the first and second intra-pixel regions and the first and second inter-pixel regions is devoid of any light emitting subpixel. Intra-pixel regions are generally regions within a pixel, while inter-pixel regions are between adjacent pixels. Each subpixel generally defines a light emitting region and since the first and second intra-pixel regions are defined to be between subpixels, the first and second intra-pixel regions are light non-emitting regions. Similarly, since the first and second inter-pixel regions are defined to be between pixels, the first and second inter-pixel regions are light non-emitting regions. In the illustrated embodiments, the first intra-pixel regions 111 are between adjacent subpixels arranged along a same row (along the x-direction) of a pixel, the second intra- pixel regions 112 are between adjacent rows of subpixels of a pixel, the first inter-pixel regions 121 are between adjacent rows of subpixels of adjacent pixels, and the second inter-pixel regions 122 can be substantially all inter-pixel regions except for the first inter-pixel regions 121. The subpixels 110, the first intra-pixel regions 111, and the first inter-pixel regions 121 define a first combined region (i.e., the first combined region is the combination of the subpixels, the first intra-pixel regions 111, and the first interpixel regions 121), and the second intra-pixel regions 112 and the second inter-pixel regions 122 define a second combined region (i.e., the second combined region is a combination of the second intra-pixel regions 112 and the second inter-pixel regions 122).

The display system 100, 100', 100" includes a light diffractive layer 150, 150', 150" configured to be between the viewer 109 and the display region 101 and disposed substantially parallel (e.g., within 20, 15, 10, or 5 degrees of parallel or nominally parallel) to, and spaced apart along a thickness direction (z-direction) of the display system 100 (or a thickness direction of the light diffractive layer) from, the display region 101. The light diffractive layer 150, 150', 150" includes a light diffractive region 152 configured to diffract light and a light non-diffractive region 154 not configured to diffract light. The light non-diffractive and diffractive regions of the light diffractive layer 150, 150', 150" can be aligned, and substantially coextensive in length and width, with the respective first and second combined regions, such that for each subpixel, for a first light emission angle al relative to the thickness direction of greater than about 10 degrees (or greater than about 15 or 20 degrees) and a second light emission angle a2 relative to the thickness direction of less than about -10 degrees (or less than about -15 or -20 degrees), and for first and second planes (yz- and xz -planes) orthogonal to one another and parallel to the thickness direction (z-direction): light 141, 142 emitted by the subpixel in the first plane (yz-plane) at each of the first and second emission angles al, a2 is diffractively transmitted (as respective transmitted light 141' and 142' at respective light propagation angles in air of al' and a2') by the light diffractive region 152 of the light diffractive layer 150, 150', 150"; and light 143, 144 emitted by the subpixel in the second plane (xz-plane) at each of the first and second emission angles al, a2 is non-diffractively transmitted (as respective transmitted light 143' and 144') through the light non-diffractive region 154 of the light diffractive layer 150, 150', 150". In some embodiments, light 140 emitted along an axial direction (z- direction) is non-diffractively transmitted (e.g., as transmitted light 140') through the light non-diffractive region 154. The light emission angles and the light propagation angles in air can be defined as positive when the direction of the light in the xz- or yz-plane projected onto the xy-plane is along the +x axis or the +y direction, respectively, and negative when the projection is along the -x or -y direction, respectively.. In some embodiments, the first light emission angle al relative to the thickness direction is greater than about 15 degrees or greater than about 20 degrees. In some embodiments, the first light emission angle al is less than about 40 degrees or less than about 35 degrees. In some embodiments, the second light emission angle a2 relative to the thickness direction is less than about -15 degrees or less than about -20 degrees. In some embodiments, the second light emission angle a2 is greater than about - 40 degrees or greater than about -35 degrees. For example, in some embodiments, 40 degrees > al > 10 degrees and -40 degrees < a2 < -10 degrees. In some embodiments, a2 is about -al.

Layers or elements can be described as substantially coextensive with each other in length and width if greater than 50% of the length and width of each layer or element is coextensive with greater than 50% of the length and width of each other layer or element. In some embodiments, for layers or elements described as substantially coextensive with each other in length and width, at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or at least about 95% of each layer or element is coextensive in length and width with at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or at least about 95% of the length and width of each other layer or element.

In some embodiments, at least 30%, or 35%, or 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85%, or 90%, or 95% of a total area of the light diffractive region of the light diffractive layer overlaps at least 30%, or 35%, or 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85%, or 90%, or 95% of a total area of the light non-emitting region of the display region. For example, in some embodiments, at least 50% of a total area of the light diffractive region of the light diffractive layer overlaps at least 50% of a total area of the light non-emitting region of the display region, or at least 75% of a total area of the light diffractive region of the light diffractive layer overlaps at least 75% of a total area of the light non-emitting region of the display region, or at least 90% of a total area of the light diffractive region of the light diffractive layer overlaps at least 80% of a total area of the light non-emitting region of the display region. In some embodiments, at least 30%, or 35%, or 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85%, or 90%, or 95% of a total area of the light non-diffractive region of the light diffractive layer overlaps at least 30%, or 35%, or 40%, or 45%, or 50%, or 55%, or 60%, or 65%, or 70%, or 75%, or 80%, or 85%, or 90%, or 95% of a total area of the light emitting region of the display region. For example, in some embodiments, at least 50% of a total area of the light non-diffractive region of the light diffractive layer overlaps at least 50% of a total area of the light emitting region of the display region, or at least 75% of a total area of the light non-diffractive region of the light diffractive layer overlaps at least 75% of a total area of the light emitting region of the display region, or at least 90% of a total area of the light non-diffractive region of the light diffractive layer overlaps at least 80% of a total area of the light emitting region of the display region.

In some embodiments, an average spacing SI between the light diffractive layer 150, 150', 150" and the display region 101 is greater than about 10, or 15, or 20, or 30, or 40, or 50, or 100, or 150, or 200, or 250, or 300, or 350, or 400, or 400, or 500 microns and less than about 5000 microns. In some embodiments, the average spacing is less than about 4500, or 4000, or 3500, or 3000, or 2500, or 2000, or 1500, or 1000, or 500, or 200, or 150 microns. In some embodiments, the average spacing SI is in a range of about 10 microns to about 5000 microns, or about 20 microns to about 4000 microns, or about 30 microns to about 2000 microns, or about 35 microns to about 200 microns, or about 40 microns to about 150 microns, for example. The spacing SI can be provided by including a layer between the light diffractive layer 150, 150', 150" and the display region 101 where the layer can be a (e.g., thin fdm) encapsulant layer and/or an (e.g., optically clear) adhesive layer, or a glass layer or another display layer such as a polarizer or touch sensor layer, for example.

The light diffractive layer 150, 150', 150" can include first and second layers 150a and 150b. In some embodiments, the first layer 150a is formed on a substrate (e.g., a polymeric substrate or another layer) using a cast and cure process where diffractive structures are fabricated from a tool by casting a polymerizable resin composition onto the substrate and curing the resin in contact with a structured surface of the tool. Such cast and cure methods are described in U.S. Pat. Nos. 5,175,030 (Lu et al.) and 5,183,597 (Lu) and in U.S. Pat. Appl. Pub. No. 2012/0064296 (Walker, JR. et al.), for example. The structured surface of the tool can be selected to define light diffractive regions and light non-diffractive regions, or the tool can define light diffraction structures throughout the structured surface of the first layer 150a and then portions of the light diffractive structures can be filled in in a subsequent coating step with a same material as used to form the first layer 150a in the cast and cure process, or a different material with a similar refractive index (e.g., substantially closer in refractive index to the cast and cure material than to the material of the second layer 150b), in order to define light non-diffractive regions. The second layer 150b can be a (e.g., planarizing) backfill layer coated over the structured surface defined in first layer 150a. The first and second layers 150a and 150b typically have different refractive indices na and nb, respectively, for at least a same first wavelength (e.g., about 550 nm) in a wavelength range of 420 nm to 680 nm, for example. In some embodiments, the difference nb-na can be at least about 0.03, 0.05, 0.07, 0.09, or 0.1 for example, for at least the first wavelength. In some such embodiments, or in other embodiments, the difference nb-na can be up to about 2, 1.5, 1, 0.8, 0.6, 0.5, or 0.4, for example, for at least the first wavelength. In some embodiments, the non-diffractive regions include a structured interface and the difference in refractive index across the structured interface can be less than about 0.08, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01, for example, for at least the first wavelength. In some embodiments, the diffractive layer 150, 150', 150" includes more than 2 materials or layers. For example, the diffractive layer 150, 150', 150" can include a thin (e.g., substantially thinner than the grating height) overcoat layer at the grating interface that may have a high refractive index (e.g., the refractive index can be at least about 2, such as a refractive index of about 2.5, for example) for at least the first wavelength. In some embodiments, at the first wavelength, the layer 150a has a refractive index of about 1.4 to about 1.55, and the layer 150b has a refractive index of about 1.75 to about 1.85. The average spacing S 1 can be in a range of about 20 to 1000 microns, the layer 150a can have a thickness of about 10 to 20 microns, and the layer 150b can have a thickness of about 5 to about 15 microns, for example. The average spacing SI may be in a range of about 20 to about 30 microns in cell phone applications, for example, and may be in a range of about 30, 35, 40, 45, 50, 60, 70, 80, or 90 microns to about 1000 microns in television applications, for example. In some embodiments, the light diffractive layer 150, 150', 150" is formed separately and then disposed on the layer 151, which can be or include an emissive layer, with an optional air gap therebetween or the light diffractive layer 150, 150', 150" can be laminated to the emissive layer.

The light diffractive and light non-diffractive regions can be patterned by any other suitable means. In some embodiments, the light diffractive and light non-diffractive regions can be patterned by inkjet printing, photolithography, masking, or other suitable patterning technologies. In some embodiments, the patterning technology determines the placement of an index matching (e.g., difference in refractive index (e.g., at 550 nm) less than about 0.08, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01, for example) material to define the location of the light non-diffractive region. In some embodiments, the patterning technology determines the placement of an index mis-matching (e.g., difference in refractive index (e.g., at 550 nm) at least about 0.03, 0.05, 0.07, 0.09, or 0. 1 for example) material to define the light diffractive regions. In some embodiments, the patterning technology defines the exposure region over which the grating is preferentially fabricated or removed by, for example, etching or scribing. In some embodiments, the light diffractive layer can be formed on the surface of another layer already present in the display system by etching or scribing where the process of etching or scribing is patterned as to define the light diffractive and light non-diffractive regions. Other methods of patterning known in the art may alternatively be utilized.

In some embodiments, the pixels 105 are arranged into rows 130 of pixels extending along an inplane first direction (x-direction) where each row of pixels includes a row 130a of subpixels 110 of the first plurality of subpixels 110a and a row 130b of subpixels 110 of the second plurality of subpixels 110b. The rows 130 can be spaced apart from one another along an in-plane second direction (y- direction) orthogonal to the first direction. In some embodiments, an average spacing Ws2a between rows of subpixels within rows of pixels is less than an average spacing Ws2b between adjacent rows of pixels. In some embodiments, Ws2a is less than 0.9, 0.8, 0.7, 0.6, or 0.5 times W2sb. In some embodiments, Ws2a is greater than an average subpixel length along the second direction. In some embodiments, the pixels 105 have an average width Wpl along the first direction (x-direction) and an average spacing between adjacent pixels along the first direction is Wsl. In some embodiments, Wsl > Wpl. In some embodiments, 5 (or 4, or 3, or 2) times Wpl > Wsl > Wpl. In some embodiments, Wsl < Wpl. In some embodiments, Wsl and Wpl are about equal.

In some embodiments, the light diffractive region 152 includes a plurality of substantially parallel linear diffractive elements extending along the first direction (x-direction) and arranged along an in-plane second direction (y-direction) orthogonal to the first direction (see, e.g., FIG. 2). In some embodiments, the light diffractive region 152 includes a two-dimensional grating (see, e.g., FIGS. 3-4) including a plurality of diffractive elements arranged along each of two orthogonal in-plane directions (e.g., the first direction (x-direction) and an in-plane second direction (y-direction) orthogonal to the first direction).

FIG. 5 is a schematic top plan view of a pixel 105, according to some embodiments. The pixel 105 includes a first plurality 110a of subpixels 11 Or 1 , 1 lOgl, and 1 lObl (e.g., red, green, and blue subpixels) and a second plurality 110b of subpixels 110r2, 110g2, and 110b2 (e.g., red, green, and blue subpixels). In some embodiments, adjacent subpixels within pixels have an average center to center spacing Wc along the first direction, and an average spacing between adjacent pixels along the first direction is Wsl, where Wsl > Wc. In some embodiments, Wsl is at least 1.5, 2, 3, or 4 times Wc. The emitted light from red (e.g., HOrl, 110r2), green (e.g., HOgl 110g2), and blue (e.g., HObl, 110b2) subpixels can include wavelengths in a visible wavelength range extending from about 400 nm to about 700 nm. For example, emitted light from blue subpixels can be blue light in a wavelength range of about 420 nm to about 490 nm, emitted light from green subpixels can be green light in a wavelength range of about 490 nm to about 590 nm, and emitted light from red subpixels can be red light in a wavelength range of about 590 nm to about 680 nm.

As is known in the art, the geometry of a grating and the refractive index difference across the grating can be selected to provide a desired first order diffraction peak in a desired direction. In some embodiments, the grating has periodic pattern with a period in a range from about 0.2 to about 5 microns, or about 0.3 to about 3.5 microns, or about 0.4 to about 3 microns, or from about 0.5 to about 2.5 microns, or from about 0.6 to about 2 microns. In some embodiments, the diffractive elements form an irregular pattern having an average spacing or pitch in any of the ranges described for the period of the periodic grating. In some embodiments, the diffractive elements has an average height in a range from about 0.05 to about 3.5 microns, or about 0. 1 to about 3.25 microns, or about 0.2 to about 3 microns, or about 0.3 to about 2.75 microns, or about 0.4 to about 2.5 microns, or from about 0.5 to about 2.25 microns, or from about 0.6 to about 2 microns, or from about 0.7 to about 1.75 microns, or from about 0.8 to about 1.5 microns, or from about 0.8 to about 1.25 microns, or from about 0.8 to about 1 microns.

As is known in the art, light diffractive structures of a light diffractive layer can be selected to diffract light into desired directions when the light is transmitted through the light diffractive layer. The light diffractive region 152 can include any suitable diffractive structures that result in light diffraction into suitable directions. For example, the light diffractive region 152 can include phase gratings, amplitude gratings, one-dimensional gratings (e.g., including substantially parallel linear diffractive elements), two-dimensional gratings (e.g., on a square, rectangular, or hexagonal lattice), subwavelength structures, metasurface structures, and/or other diffractive structures known in the art. In some embodiments, the light diffractive structures form a grating, and the geometry and refractive indices of the light diffractive structures can be related to the desired directions by a diffraction grating equation, for example. Illustrative diffractive structures described by diffraction grating equations can be found in “Design and fabrication of binary slanted surface -relief gratings for a planar optical interconnection”, Miller et al., Applied Optics, Vol. 36, No. 23, 1997 and “Formulation for stable and efficient implementation of the rigorous coupled-wave analysis of binary gratings”, Moharam et al., J. Opt. Soc. Am. A, Vol. 12, No. 5, 1995, for example. In some embodiments, the light diffractive structures form a metasurface (which can be considered to be a diffractive surface) that provides suitable steering into desired directions. Illustrative metasurfaces for beam steering are described in U.S. Pat. Appl. Publ. No., 2021/0109364 (Aieta et al.) and “Free-Form Diffractive Metagrating Design Based on Generative Adversarial Networks”, Jiang et al., ACS Nano, 13, 8872-8878, 2019, for example. The geometry of the diffractive elements can be selected, in part, based on the geometry of the pixel and subpixel layout and/or in part on desired luminance profdes along a horizontal direction (e.g., in xz-plane) and/or along a vertical direction (e.g., in yz -plane).

FIG. 5 is a schematic plot of emission spectra of subpixels, according to some embodiments. Emission spectra 200b, 200g, and 200r are schematically illustrated. In some embodiments, each of subpixels 1 lOrl and 110r2 have a substantially same (e.g., same, or nominally same, or same to within 10 or 5 percent variation) emission spectrum 200r (e.g., red), each of subpixels 1 lOgl and 110g2 have a substantially same emission spectrum 200g (e.g., green), and each of subpixels 1 lObl and 110b2 have a substantially same emission spectrum 200b (e.g., blue).

FIGS. 7A-7D show normalized luminance profde plots for display systems including diffractive layers with linear diffractive elements, according to some embodiments. The pixel layout was generally as shown in FIG. 4 with linear diffractive elements as shown in FIG. 2. The luminance profdes were determined using conventional ray tracing techniques. The diffractive gratings were simulated via rigorous coupled wave analysis (RCWA) and the scattering information was then compiled for utilization during the ray trace. The linear diffractive elements were modeled as being arranged at an 800 nm pitch with 850 nm height, 500 nm ridge width, and low and high refractive indices of 1.52 and 1.72, respectively. The grating was disposed with a spacing SI of 100 microns. Normalized luminance was determined as the luminance divided by the luminance at a polar angle of zero degrees of a comparative display system having a same construction as the display system except that that the light diffractive layer was not included in the comparative display system. In each case, the luminance of the display system was normalized by the luminance of the comparative display system with the same subpixels illuminated (e.g., only the first plurality of subpixels, only the second plurality of subpixels, or the combination of the first and second pluralities).

FIGS. 7A-7D shows normalized luminance profiles 301v, 302v, 301v', 302v', 310v, 301h, 302h, 30 lh', 302h', 3 lOh of light exiting a display system in air as a function of light propagation angle (polar angle) in a first plane (yz-plane or vertical plane for 30 Iv, 302v, 30 lv', 302v', 3 lOv) or in an orthogonal second plane (xz-plane or horizontal plane for 301h, 302h, 301h', 302h', 310h). Normalized luminance profiles 30 lv and 302v of FIG. 7A and 30 lh and 302h of FIG. 7B are for when a light diffractive layer 150 as schematically illustrated in FIG. 2 is included in the display system. Normalized luminance profiles 30 lv' and 302v' of FIG. 7C and 30 lh' and 302h' of FIG. 7D are for when a light diffractive layer 150 similar to that schematically illustrated in FIG. 2 but without the grating in intra-pixel regions 112 is included in the display system. Normalized luminance profiles 3 lOv and 3 lOh in respective vertical and horizontal planes are for a comparative display system having a same construction as the display system but not including the light diffractive layer. The light propagation angles (polar angles) in these figures are relative to the normal or thickness direction (z-direction in FIG. 2). The normalized luminance profile 301v, 301v', 301h, 30 lh' results when all subpixels in the first plurality of subpixels 110a of all pixels of the display region 101 emit light, but no subpixels in the second plurality of subpixels 110b emit light, while the normalized luminance profile 302v, 302v', 302h, 302h' results when all subpixels of each of the first and second pluralities of subpixels 110a, 110b of all pixels of the display region 101 emit light (or when all subpixels of all pixels of the display regions 101 emit light). The normalized intensities 3 lOv, 3 lOh can be determined either using the first plurality of subpixels 110a or the combined plurality of subpixels 110a, 110b due to the symmetry of the pattern of subpixels.

The normalized luminance profiles 30 lv and 302v are substantially the same (e.g., same, or nominally same, or same within 10 or 5 percent variation) at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees, or about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees. The normalized luminance profiles 30 lh and 302h are substantially the same at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees, or about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees. The normalized luminance profiles 30 lv' and 302v' are substantially different for light propagation angle relative to the thickness direction throughout most of the range of about -70 degrees to about 70 degrees. The normalized luminance profiles 30 lh' and 302h' are substantially different for light propagation angle relative to the thickness direction of about -45 degrees and about 45 degrees since the normalized intensities 30 lh' and 302h' differ from one another by greater than 10% at each of these light propagation angles.

The normalized luminance profiles 301v, 302v, 302v', and 3 lOv, but not the normalized luminance profile 30 lv', as a function of light propagation angle relative to the thickness direction is substantially symmetric (e.g., symmetric, or nominally symmetric, or symmetric up to deviations of no more than about 10 or 5 percent) about a second plane (e.g., xz-plane comprising the light propagation angle of 0 degrees) orthogonal to the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about - 65 degrees to about 65 degrees). Symmetry about a plane should be understood to be a reflection symmetry about the plane. The normalized luminance profiles 301h, 302h, 302h', and 310h, but not the normalized luminance profile 30 lh', as a function of light propagation angle relative to the thickness direction is substantially symmetric (e.g., symmetric, or nominally symmetric, or symmetric up to deviations of no more than about 10 or 5 percent) about the first plane (e.g., yz-plane comprising the light propagation angle of 0 degrees) at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees).

FIG. 8 shows luminance profile plots for a display system including a diffractive layer including a two-dimensional grating (see, e.g., FIG. 4), according to some embodiments. The plots of FIG. 8 were generated as generally described for FIGS. 7A-7D except that a two-dimensional grating was used. This grating had a square unit cell with pitch of 800 nm and square pillars with dimensions (length in x- direction, width in y-direction, and height in z-direction) of 400 nm x 400 nm x 1350 nm and was disposed with a spacing SI of 40 microns. The grating included two materials with low and high refractive indices of 1.52 and 1.74, respectively. Normalized luminance profiles 402v and 402h of light exiting a display system in air as a function of light propagation angle (polar angle) in respective first (yz or vertical) and second (xz or horizontal) planes are shown. The normalized luminance profile 402v in the first plane is substantially symmetric about the second plane, and the normalized luminance profile 402h in the second plane is substantially symmetric about the first plane. A normalized luminance profile 410, which is substantially the same in the first and second planes, for a comparative display system not including the light diffractive layer is also shown. The normalized luminance profdes 420v, 420h, and 410 were determined for all green subpixels emitting light.

In some embodiments, for each of the first plurality of subpixels 110a and a combined plurality of subpixels 110a and 110b including the first and second pluralities of subpixels, light (e.g., 141, 142, 143, 144) emitted by the subpixels is transmitted by the light diffractive layer 150, 150', 150" and exits the display system in air toward the viewer 109 where at least some of the emitted light is diffractively transmitted by the light diffractive layer, with the exiting light having a substantially same (substantially the same for the first plurality of subpixels and for the combined plurality of subpixels) normalized luminance profile as a function of light propagation angle in the first plane (yz-plane) relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees, or about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees and/or with the exiting light having a substantially same (substantially the same for the first plurality of subpixels and for the combined plurality of subpixels) normalized luminance profile as a function of light propagation angle in the second plane (xz -plane) relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees, or about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees. In other words, in some embodiments, the exiting light in at least one of the first and second planes has a normalized luminance profile that is substantially the same for the first plurality of subpixels and for the combined plurality of subpixels.

In some embodiments, for each of the first plurality of subpixels 110a and a combined plurality of subpixels 110a and 110b including the first and second pluralities of subpixels, light (e.g., 141, 142, 143, 144) emitted by the subpixels is transmitted by the light diffractive layer 150, 150', 150" and exits the display system in air toward the viewer 109 with at least some of the emitted light being diffractively transmitted by the light diffractive layer, where in the first plane, the exiting light has a first luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about the second plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees); and in the second plane, the exiting light has a second luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees).

In some embodiments, a display system 100 includes a display region 101 configured to form an image 107 thereacross for viewing by a viewer 109 and including a plurality of pixels 105 defining a light emitting region (region of subpixels 110) configured to emit light and a light non-emitting region 120 not configured to emit light. Each pixel 105 includes nonoverlapping first and second pluralities 110a and 110b of subpixels. Each of the first and second pluralities 110a and 110b including at least three different subpixels (e.g., HOrl, HOgl, HObl and 110r2, 110g2, 110b2) having at least three different emission spectra (e.g., 200r, 200g, and 200b). The display system 100 includes a light diffractive layer 150, 150', 150" configured to be between the viewer 109 and the display region 101 and disposed substantially parallel to, and spaced apart along a thickness direction (z-direction) of the display system from, the display region 101. The light diffractive layer 150, 150', 150" includes a light diffractive region 152 configured to diffract light and a light non-diffractive region 154 not configured to diffract light. The light diffractive region is aligned, and substantially coextensive in length and width, with a first nonemitting region of the light non-emitting region 120. The light non-diffractive region is aligned, and substantially coextensive in length and width, with a region including the light emitting region (region of subpixels 110) and a second non-emitting region (e.g., regions 121 and 111) of the light non-emitting region 120.

In some embodiments, the first and second non-emitting regions are non-overlapping regions selected from the light non-emitting region 120 so that for each of the first plurality of subpixels 110a and a combined plurality of subpixels 110a, 110b including the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer 150, 150', 150" and exits the display system 100 in air toward the viewer, at least some of the emitted light being diffractive ly transmitted by the light diffractive layer, such that: in a first plane (e.g., xz-plane) parallel to the thickness direction (z- direction), the exiting light has a substantially same (substantially the same for the first plurality of subpixels and for the combined plurality of subpixels) first normalized luminance profile as a function of light propagation angle relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees); and in a second plane (e.g., yz-plane) parallel to the thickness direction and orthogonal to the first plane, the exiting light has a substantially same (substantially the same for the first plurality of subpixels and for the combined plurality of subpixels) second normalized luminance profile as a function of light propagation angle relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees).

In some embodiments, the first and second non-emitting regions are non-overlapping regions selected from the light non-emitting region so that for each of the first plurality 110a of subpixels and a combined plurality 110a, 110b of subpixels including the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer 150, 150', 150" and exits the display system 100 in air toward the viewer, at least some of the emitted light being diffractive ly transmitted by the light diffractive layer, such that: in a first plane (e.g., xz-plane) parallel to the thickness direction (z- direction), the exiting light has a first luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about a second plane (e.g., yz-plane) parallel to the thickness direction and orthogonal to the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about - 65 degrees to about 65 degrees); and in the second plane, the exiting light has a second luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees (e.g., for light propagation angle in a range of about -55 degrees to about 55 degrees, or about -60 degrees to about 60 degrees, or about -65 degrees to about 65 degrees).

The light diffractive region 152 can include any diffractive structure described elsewhere. In some embodiments, the light diffractive region 152 includes a plurality of substantially parallel linear diffractive elements extending along an in-plane first direction (x-direction) and arranged along an inplane second direction (y-direction) orthogonal to the first direction (see, e.g., FIG. 2). In some embodiments, the light diffractive region 152 includes a two-dimensional grating including a plurality of diffractive elements arranged along each of orthogonal in-plane first and second directions (see, e.g., FIG. 3).

For any of the display systems of the present description, the light diffractive layer 150, 150', 150" can cause an on-axis luminance of light exiting the display system to increase by at least about 20%, for example. In some embodiments, for at least a same one (e.g., 1 lOgl, 110g2) of the at least three different subpixels of each of the first and second pluralities of subpixels 110a, 110b of each of the pixels 105, when light emitted by the subpixels is transmitted by the light diffractive layer 150, 150', 150" and exits the display system in air toward the viewer, the light diffractive layer 150, 150', 150" causes an on- axis (e.g., along z-axis) luminance of the exiting light to increase by at least about 20, 25, 30, 35, or 40 percent. The increase can be up to about 100, 90, or 80 percent, for example. The increase is relative to the display system without the light diffractive layer 150, 150', 150". For example, the light diffractive layer 150, 150', 150" causing an on-axis luminance of the exiting light to increase by at least 20% means that the on-axis luminance is at least 1.2 times a corresponding on-axis luminance of a comparative display system having a same construction as the display system except that the comparative display system does not include the light diffractive layer 150, 150', 150". In other words, the normalized luminance relative to the comparative display system at a light propagation angle of 0 degrees can be at least 1.2.

For any of the display systems of the present description, the light diffractive layer 150, 150', 150" can cause a luminance of light exiting the display system to have a full width at a specified fraction of a maximum luminance in a plane to be substantially greater for one plane than an orthogonal plane. The specified fraction can be i or %, for example. In some embodiments, for at least a same one (e.g., 1 lOgl, 110g2) of the at least three different subpixels of each of the first and second pluralities of subpixels 110a, 110b of each of the pixels 105, when light emitted by the subpixels is transmitted by the light diffractive layer 150, 150', 150" and exits the display system in air toward the viewer, the exiting light has a luminance as function of light propagation angle relative to the thickness direction (z- direction) that has a full width at % maximum of less than about 50 degrees in a first plane (e.g., yz- plane) and greater than about 80 degrees in a second plane (e.g., xz-plane). The first and second planes can be orthogonal to one another and parallel to the thickness direction. The full width at % maximum can be less than about 45, 40, or 35 degrees in the first plane. The full width at % maximum can be greater than about 90, 100, 110, 120, 130, or 140 degrees in the second plane. For example, in FIG. 7A, the normalized luminance 302v in the first (vertical) plane has a maximum of about 1.57 at a light propagation angle of about zero degrees and a full width at % maximum (about 1.18) of about 29 degrees, and in FIG. 7B, the normalized luminance 302h in the second (horizontal) plane has a maximum of about 1.84 at light propagation angles of about ±40 degrees and a full width at % maximum (about 1.38) of about 100 degrees. As another example, in FIG. 8, the normalized luminance 402v in the first (vertical) plane has a maximum of about 1.5 at a light propagation angle of about zero degrees and a full width at % maximum (about 1.1) of about 35 degrees, and the normalized luminance 402h in the second (horizontal) plane has a maximum of about 1.5 at a light propagation angle of about 0 degrees and a full width at % maximum (about 1.1) of about 150 degrees.

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

Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially” with reference to a property or characteristic is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description and when it would be clear to one of ordinary skill in the art what is meant by an opposite of that property or characteristic, the term “substantially” will be understood to mean that the property or characteristic is exhibited to a greater extent than the opposite of that property or characteristic is exhibited.

All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations, or variations, or combinations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed is:

1. A display system comprising: a display region comprising a plurality of pixels configured to form an image thereacross for viewing by a viewer, each pixel comprising three or more subpixels, the subpixels defining nonoverlapping first and second intra-pixel regions therebetween for each pixel, the pixels defining nonoverlapping first and second inter-pixels therebetween, each of the first and second intra-pixel regions and the first and second inter-pixel regions devoid of any light emitting subpixel, the subpixels, the first intra-pixel regions, and the first inter-pixel regions defining a first combined region, the second intra- pixel regions and the second inter-pixel regions defining a second combined region; and a light diffractive layer configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region, the light diffractive layer comprising a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light, the light non-diffractive and diffractive regions of the light diffractive layer aligned, and substantially coextensive in length and width, with the respective first and second combined regions, such that for each subpixel, for a first light emission angle relative to the thickness direction of greater than about 10 degrees and a second light emission angle relative to the thickness direction of less than about -10 degrees, and for first and second planes orthogonal to one another and parallel to the thickness direction: light emitted by the subpixel in the first plane at each of the first and second emission angles is diffractively transmitted by the light diffractive region of the light diffractive layer; and light emitted by the subpixel in the second plane at each of the first and second emission angles is non-diffractively transmitted through the light non-diffractive region of the light diffractive layer.

2. The display system of claim 1, wherein each pixel comprises nonoverlapping first and second pluralities of subpixels, each of the first and second pluralities comprising at least three different subpixels having at least three different emission spectra.

3. The display system of claim 2, wherein for each of the first plurality of subpixels and a combined plurality of subpixels comprising the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, at least some of the emitted light being diffractively transmitted by the light diffractive layer, the exiting light having a substantially same normalized luminance profile as a function of light propagation angle in the first plane relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees.

4. The display system of claim 2, wherein for each of the first plurality of subpixels and a combined plurality of subpixels comprising the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, at least some of the emitted light being diffractively transmitted by the light diffractive layer, the exiting light having a substantially same normalized luminance profile as a function of light propagation angle in the second plane relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees.

5. The display system of claim 2, wherein the pixels are arranged into rows of pixels extending along an in-plane first direction, each row of pixels comprising a row of subpixels of the first plurality of subpixels and a row of subpixels of the second plurality of subpixels an average spacing between rows of subpixels within rows of pixels is less than an average spacing between adjacent rows of pixels.

6. The display system of claim 5, wherein the light diffractive region comprises a plurality of substantially parallel linear diffractive elements extending along the first direction and arranged along an in-plane second direction orthogonal to the first direction.

7. The display system of any one of claims 1 to 5, wherein the light diffractive region comprises a two- dimensional grating comprising a plurality of diffractive elements arranged along each of two orthogonal in-plane directions.

8. A display system comprising: a display region configured to form an image thereacross for viewing by a viewer and comprising a plurality of pixels defining a light emitting region configured to emit light and a light non-emitting region not configured to emit light, each pixel comprising nonoverlapping first and second pluralities of subpixels, each of the first and second pluralities comprising at least three different subpixels having at least three different emission spectra; and a light diffractive layer configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region, the light diffractive layer comprising a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light, the light diffractive region aligned, and substantially coextensive in length and width, with a first non-emitting region of the light non-emitting region, the light non-diffractive region aligned, and substantially coextensive in length and width, with a region comprising the light emitting region and a second non-emitting region of the light non-emitting region, wherein the first and second non-emitting regions are non-overlapping regions selected from the light non-emitting region so that for each of the first plurality of subpixels and a combined plurality of subpixels comprising the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, at least some of the emitted light being diffractively transmitted by the light diffractive layer, such that: in a first plane parallel to the thickness direction, the exiting light has a substantially same first normalized luminance profile as a function of light propagation angle relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees; and in a second plane parallel to the thickness direction and orthogonal to the first plane, the exiting light has a substantially same second normalized luminance profile as a function of light propagation angle relative to the thickness direction at least for light propagation angle in a range of about -50 degrees to about 50 degrees.

9. The display system of claim 8, wherein for at least a same one of the at least three different subpixels of each of the first and second pluralities of subpixels of each of the pixels, when light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, the light diffractive layer causes an on-axis luminance of the exiting light to increase by at least 20 percent.

10. The display system of claim 8 or 9, wherein the light diffractive region comprises a plurality of substantially parallel linear diffractive elements extending along an in-plane first direction and arranged along an in-plane second direction orthogonal to the first direction.

11. The display system of claim 8 or 9, wherein the light diffractive region comprises a two-dimensional grating comprising a plurality of diffractive elements arranged along each of orthogonal in-plane first and second directions.

12. A display system comprising: a display region configured to form an image thereacross for viewing by a viewer and comprising a plurality of pixels defining a light emitting region configured to emit light and a light non-emitting region not configured to emit light, each pixel comprising nonoverlapping first and second pluralities of subpixels, each of the first and second pluralities comprising at least three different subpixels having at least three different emission spectra; and a light diffractive layer configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region, the light diffractive layer comprising a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light, the light diffractive region aligned, and substantially coextensive in length and width, with a first non-emitting region of the light non-emitting region, the light non-diffractive region aligned, and substantially coextensive in length and width, with a region comprising the light emitting region and a second non-emitting region of the light non-emitting region, wherein the first and second non-emitting regions are non-overlapping regions selected from the light non-emitting region so that for each of the first plurality of subpixels and a combined plurality of subpixels comprising the first and second pluralities of subpixels, light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, at least some of the emitted light being diffractively transmitted by the light diffractive layer, such that: in a first plane parallel to the thickness direction, the exiting light has a first luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about a second plane parallel to the thickness direction and orthogonal to the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees; and in the second plane, the exiting light has a second luminance profile as a function of light propagation angle relative to the thickness direction that is substantially symmetric about the first plane at least for light propagation angle relative to the thickness direction in a range of about -50 degrees to about 50 degrees.

13. The display system of claim 12, wherein for at least a same one of the at least three different subpixels of each of the first and second pluralities of subpixels of each of the pixels, when light emitted by the subpixels is transmitted by the light diffractive layer and exits the display system in air toward the viewer, the light diffractive layer causes an on-axis luminance of the exiting light to increase by at least 20 percent.

14. The display system of claim 12 or 13, wherein the light diffractive region comprises a plurality of substantially parallel linear diffractive elements extending along an in-plane first direction and arranged along an in-plane second direction orthogonal to the first direction.

15. The display system of claim 12 or 13, wherein the light diffractive region comprises a two- dimensional grating comprising a plurality of diffractive elements arranged along each of orthogonal inplane first and second directions.