Selectively patterned optical diffraction films

Abstract

A display system includes a display region having a light emitting region and a light non-emitting region, and a light diffractive layer. The light diffractive layer includes first and second one-dimensional diffraction sublayers. The first one-dimensional diffraction sublayer includes a first light diffractive area and a first non-diffractive area, and the second one-dimensional diffraction sublayer includes a second light diffractive area and a second non-diffractive area. A first portion of the light non-emitting region is covered by the first light diffractive area but not the second light diffractive area, a second portion of the light non-emitting region is covered by the second light diffractive area but not the first light diffractive area, a third portion of the light non-emitting region is covered by both the first light diffractive area and the second light diffractive area, and the light emitting region is not covered by either the first or second light diffractive areas.

Description

[0001] SELECTIVELY PATTERNED OPTICAL DIFFRACTION FILMS

[0002] Technical Field

[0003] The present description relates generally to display systems.

[0004] Background

[0005] A display system can include a micro-light emitting diode (micro-LED) display panel.

[0006] Summary

[0007] In some aspects of the present description, a display system is provided, the display system including a display region configured to form an image thereacross for viewing by a viewer and having a light emitting region configured to emit light and leaving a remaining 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. The light diffractive layer including a first one-dimensional diffraction sublayer and a second one-dimensional diffraction sublayer disposed on, and substantially coextensive in length and width with, the first one-dimensional diffraction sublayer. The first one-dimensional diffraction sublayer includes a first light diffractive area leaving a remaining first non-diffractive area. The second one-dimensional diffraction sublayer includes a second light diffractive area leaving a remaining second non-diffractive area. A first portion of the light non-emitting region is covered by the first light diffractive area of the first one-dimensional diffraction sublayer but not by the second light diffractive area of the second one-dimensional diffraction sublayer. A second portion of the light nonemitting region, different from the first portion, is covered by the second light diffractive area of the second one-dimensional diffraction sublayer but not by the first light diffractive area of the first onedimensional diffraction sublayer. A third portion of the light non-emitting region, different from the first portion and the second portion, is covered by both the first light diffractive area of the first onedimensional diffraction sublayer and the second light diffractive area of the second one-dimensional diffraction sublayer, so that at least 80% of the light non-emitting region is covered by at least one of the first and second diffractive areas. At least 80% of the light emitting region is not covered by either the first light diffractive area of the first one-dimensional diffraction sublayer or the second light diffractive area of the second one-dimensional diffraction layer.

[0008] In some aspects of the present description, a display system is provided, the display system including a display region configured to form an image thereacross for viewing by a viewer and including a plurality of light emitting elements defining, in combination, a light emitting region configured to emit light and leaving a remaining 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. The light diffractive layer includes a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two-dimensional diffraction regions.

[0009] In some aspects of the present description, a light diffractive layer is provided, the light diffractive area configured to be disposed between a viewer and a display region of a display configured to form an image thereacross for viewing by the viewer and including a plurality of spaced-apart, lightemitting elements separated by one or more light non-emitting regions. The light diffractive layer includes a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart onedimensional diffraction regions and a plurality of spaced-apart two-dimensional diffraction regions. The non-diffractive regions of the plurality of spaced-apart non-diffractive regions are configured to be substantially aligned, in a one-to-one relationship with, the light emitting elements of the plurality of light emitting elements of the display region. At least 80% of the light non-emitting regions of the display region are covered by one of a one-dimensional diffraction region of the plurality of spaced-apart onedimensional diffraction regions and a two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions.

[0010] In some aspects of the present description, a display system is provided, the display system including a display region comprising a plurality of spaced-apart light-emitting elements separated by light non-emitting regions, and a light diffractive layer disposed on, and spaced apart along a thickness direction of the display system from, the light emitting elements. The light diffractive layer includes, from a top plan view, a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two-dimensional diffraction regions. Each non-diffractive region of the plurality of spaced-apart non-diffractive regions is substantially aligned in a one-to-one relationship with a corresponding light emitting element of the plurality of light emitting elements of the display region. At least 80% of the light non-emitting regions of the display region are covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two-dimensional grating of the plurality of spaced-apart two-dimensional diffraction regions. Light emitted by the light emitting elements is diffractively transmitted by the light diffractive layer and exits the display system in air toward a viewer. The exiting light has a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a linear direction of at least one of the one-dimensional diffraction regions. For at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the normalized luminance profile (i.e., normalized with respect to a comparative display without the light diffractive layer) has a normalized peak luminance, and a full width at half maximum (FWHM), a ratio of the normalized peak luminance to the FWHM being greater than about 0.007 degrees1.

[0011] In some aspects of the present description, a display system is provided, the display system including a display region comprising a plurality of spaced-apart light-emitting elements separated by light non-emitting regions, and a light diffractive layer disposed on, and spaced apart along a thickness direction of the display system from, the light emitting elements. The light diffractive layer includes, from a top plan view, a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two-dimensional gratings. Each non- diffractive region of the plurality of spaced-apart non-diffractive regions is substantially aligned in a one- to-one relationship with a corresponding light emitting element of the plurality of light emitting elements of the display region. At least 80% of the light non-emitting regions of the display region are covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions. Light emitted by the light emitting elements is diffractively transmitted by the light diffractive layer and exits the display system in air toward a viewer. The exiting light has a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a linear direction of at least one of the one-dimensional diffraction regions. For at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes an on-axis luminance of the normalized luminance profile to increase by at least a factor of 10%.

[0012] Brief Description of the Drawings

[0013] FIG. 1 A is a top plan view of a display region of a display system, in accordance with an embodiment of the present description;

[0014] FIG. IB is a top plan view of a first one-dimensional diffraction sublayer of a display system, in accordance with an embodiment of the present description;

[0015] FIG. 2A is a top plan view of a second one-dimensional diffraction sublayer of a display system, in accordance with an embodiment of the present description;

[0016] FIG. 2B is a top plan view of a display system with superimposed first and second onedimensional diffraction sublayers, in accordance with an embodiment of the present description;

[0017] FIG. 3A is a side view of a display system with superimposed first and second one-dimensional diffraction sublayers, in accordance with an embodiment of the present description;

[0018] FIG. 3B is an alternate side view of a display system with superimposed first and second onedimensional diffraction sublayers, in accordance with an embodiment of the present description;

[0019] FIG. 4A is a top plan view of a display system with a light diffraction layer having a plurality of one-dimensional diffraction regions and a plurality of two-dimensional diffraction regions, in accordance with an embodiment of the present description;

[0020] FIG. 4B is a side view of a display system with a light diffraction layer having a plurality of onedimensional diffraction regions and a plurality of two-dimensional diffraction regions, in accordance with an embodiment of the present description;

[0021] FIG. 5 is a side view of a display system showing how light is diffractively transmitted by a onedimensional diffraction sublayer, in accordance with an embodiment of the present description; and FIG. 6 is a plot of normalized luminance values versus polar viewing angle for several embodiments of a display system, in accordance with an embodiment of the present description, and a comparative example display system.

[0022] Detailed Description

[0023] 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.

[0024] 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 intensity and the brightness experienced by the viewer. It is often desired that the light output having the increase in axial brightness (luminance) have a desired (e.g., symmetric) intensity 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 intensity 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 intensity profile.

[0025] Diffraction structures have been used as light diffractive layers 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 layer is placed over an entire emissive layer with the diffraction region 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 structures have also been used over light non-emitting regions of a display to increase axial efficiency of the display as described in International App. Pub. No. WO 2024 / 033838 (DeSutter et al.).

[0026] For the purposes of this description, the terms “diffractive” and “diffraction” when used as modifiers (e.g., “diffractive layer” or "diffraction region”) shall be considered to be synonymous with each other. That is, both shall be interpreted to refer to a region, layer, surface, or other element of the present description which is referred to my either term that is at least partially covered in features or surfaces which cause a diffraction of light passing through them.

[0027] In addition, when the modifier “one-dimensional” is used to refer to a region, layer, or sublayer (as in “one-dimensional diffraction sublayer”, it shall be interpreted to mean that the element being modified by “one-dimensional” at least includes one-dimensional diffractive features or surfaces (i.e., features or surfaces aligned to at least a first linear direction), but may also include other types of features. For example, in some embodiments, a “one-dimensional” region, layer, or sublayer may also include other features / surfaces, including “two-dimensional” features / surfaces, such as a grid pattern, a hexagonal pattern, or other pattern with features crossing or intersecting in two separate directions.

[0028] According to some aspects of the present description, a display system may include a display region configured to form an image thereacross for viewing by a viewer and a light diffractive layer. In some embodiments, the display region may include a light emitting region (e.g., a number of light emitting diodes creating pixels on the display) configured to emit light and leaving a remaining light nonemitting region (e.g., the region between pixels) not configured to emit light.

[0029] In some embodiments, the light diffractive layer may be configured to be between the viewer and the display region and may be disposed substantially parallel to, and spaced apart along a thickness direction (e.g., a z-axis) of the display system from, the display region. In some embodiments, the light diffractive layer may include a first one-dimensional diffraction sublayer and a second one-dimensional diffraction sublayer disposed on, and substantially coextensive in length and width with, the first onedimensional diffraction sublayer.

[0030] In some embodiments, the first one-dimensional diffraction sublayer may have a first light diffractive area (e.g., area of the one-dimensional diffraction sublayer that has diffractive features) leaving a remaining first non-diffractive area (e.g., area of the one-dimensional diffraction sublayer without any diffractive features). In some embodiments, the second one-dimensional diffraction sublayer may include a second light diffractive area leaving a remaining second non-diffractive area.

[0031] In some embodiments, a first portion of the light non-emitting region may be covered by the first light diffractive area of the first one-dimensional diffraction sublayer but not by the second light diffractive area of the second one-dimensional diffraction sublayer. In some embodiments, a second portion of the light non-emitting region, different from the first portion, may be covered by the second light diffractive area of the second one-dimensional diffraction sublayer but not by the first light diffractive area of the first one-dimensional diffraction sublayer. In some embodiments, a third portion of the light non-emitting region, different from the first portion and the second portion, may be covered by both the first light diffractive area of the first one-dimensional diffraction sublayer and the second light diffractive area of the second one-dimensional diffraction sublayer.

[0032] In some embodiments, at least 80% of the light non-emitting region may be covered by at least one of the first and second diffractive areas. In some embodiments, at least 80% of the light emitting region may not be covered by either the first light diffractive area of the first one-dimensional diffraction sublayer or the second light diffractive area of the second one-dimensional diffraction sublayer.

[0033] In some embodiments, the first light diffractive area of the first one-dimensional diffraction sublayer may include linear gratings aligned along a first direction, and the second light diffractive area of the second one-dimensional diffraction sublayer may include linear gratings aligned along a different, second direction. In some such embodiments, the first direction and the second direction may be substantially orthogonal to each other. In this manner, by overlaying the first one-dimensional diffraction sublayer and the second grating area, a diffractive layer may be created which include areas with no gratings, areas with one-dimensional diffraction regions (i.e., areas having only one set of gratings, either aligned with the first direction or the second direction), and areas with two-dimensional diffraction regions (i.e., areas of the light diffractive layer in which the linear gratings from the first one-dimensional diffraction sublayer are overlaid with the linear gratings of the second one-dimensional diffraction sublayer, creating crossed grating features in the light diffractive layer).

[0034] Although the figures and embodiments described herein are shown using linear gratings to create the one-dimensional and two-dimensional diffraction regions, this is not intended to be limiting. Onedimensional diffraction regions and two-dimensional diffraction regions can, in other embodiments, be created using other diffractive features and methods.

[0035] For the purposes of this descriptions, and as is known in the art, light diffractive structures of a light diffractive layer or region may be any structures which are configured to deflect light into desired directions when the light is transmitted through the light diffractive layer. The light diffractive region can include any suitable diffractive structures that result in light diffraction into suitable directions. For example, the light diffractive region 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 may 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, 20 1995, for example. In some other embodiments, the light diffractive structures may form a metasurface (which can be considered to be a diffractive surface or region) that provides suitable steering into desired directions. Illustrative metasurfaces for beam steering are described in U.S. Pat. No., 11,733,535 (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 layout. For example, when pixels are arranged into rows, substantially parallel linear diffractive elements extending along regions between the rows may be preferred, while when pixels are arranged in a pentile or rectangular grid arrangement, a two-dimensional diffraction region may be preferred.

[0036] In some embodiments of the display system, light emitted by the light emitting region may be diffractively transmitted by the light diffractive layer and may exit the display system in air toward the viewer. In some such embodiments, the exiting light may have a normalized intensity profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the normalized intensity profile has a normalized peak intensity, and a full width at half maximum (FWHM), such that a ratio of the normalized peak intensity to the FWHM is greater than about 0.007 degrees1, or about 0.008 degrees1, or about 0.009 degrees1, or about 0.01 degrees1, or about 0.02 degrees1, or about 0.03 degrees1, or about 0.04 degrees1, or about 0.05 degrees1.

[0037] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause a full width at half maximum of the normalized intensity profile to decrease by at least a factor of about 10%, or about 20%, or about 30%, or about 50%, or about 60%, or about 70%.

[0038] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause an on-axis intensity of the normalized intensity profile to increase by at least a factor of about 10%, or about 15%, or about 20%, or about 30%, or about 40%, or about 50%, or about 75%, or about 100%, or about 125%, or about 150%.

[0039] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause a change in the slope for positive viewing angles of the normalized intensity profile to decrease. For example, in comparative display systems which do not include the light diffractive layer as described herein, the on-axis intensity (i.e., the intensity / percentage of light transmitted at a viewing angle of about 0 degrees) may be less than an intensity / percentage of light transmitted at a larger, off-axis viewing angle (e.g., the intensity at positive 45 degrees viewing angle, or 55 degrees, or 60 degrees). For example, the intensity profile of a display system not including the light diffractive layer may be “saddle-shaped”, with peak intensities at viewing angles of positive 50 degrees and negative 50 degrees, with a dip in intensity near the on-axis (0 degree) viewing angle. This shape will cause a slope of the plot to be positive (climbing upward) from 0 degrees to +50 degrees viewing angles. The inclusion of the light diffractive layer as described herein may cause that positive slope from 0 degrees to +50 degrees to decrease (flatten out) or even change to a negative slope (descending between 0 degrees to +50 degrees as the peak intensity at 0 degrees is increased by the presence of the light diffractive layer).

[0040] According to some aspects of the present description, a display system may include a display region configured to form an image thereacross for viewing by a viewer, and a light diffractive layer. In some embodiments, the display region may include a plurality of light emitting elements (e.g., light emitting diodes) defining, in combination, a light emitting region configured to emit light and leaving a remaining light non-emitting region not configured to emit light (e.g., the space between light emitting diodes).

[0041] In some embodiments, the light diffractive layer may be configured to be between the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction (e.g., a z-axis) of the display system from, the display region. In some embodiments, the light diffractive layer may include a plurality of spaced-apart non-diffractive regions (e.g., regions without diffractive features) separated by a plurality of spaced-apart one-dimensional diffraction regions (having diffractive features or surfaces aligned along a single direction) and a plurality of spaced-apart two-dimensional diffraction regions (having diffractive features or surfaces going in two different, possibly orthogonal directions, and crossing to create the two-dimensional diffraction regions).

[0042] In some embodiments of the display system, each non-diffractive region of at least 50% of the non-diffractive regions of the plurality of spaced-apart non-diffractive regions may be substantially aligned in a one-to-one relationship with a corresponding light emitting element of the plurality of light emitting elements. In some embodiments, for example, no more than 20%, or no more than 10%, or no more than 5%, or no more than 1%, of the light emitting region (i.e., the region including the light emitting elements) may be covered by either a one-dimensional diffraction region or a two-dimensional diffraction region.

[0043] In some embodiments, at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 99%, of the remaining light non-emitting region may be covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions.

[0044] In some embodiments, the light diffractive layer may be a single, integral layer. In other embodiments, the light diffractive layer may include a first one-dimensional diffraction sublayer comprising first areas of linear grating structures aligned along a first direction (e.g., x-direction) and separated by areas without grating structures aligned along the same first direction, and a second onedimensional diffraction sublayer comprising second areas of linear grating structures aligned along a second direction (e.g., y-direction) substantially orthogonal to the first direction and separated by areas without grating structures aligned along the same second direction. In some embodiments, each onedimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions may corresponds to an area of the light diffractive layer that is substantially covered by one of a first area of linear grating structures and a second area of linear grating structures, but not by both the first area and the second area. In some embodiments, each two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions may correspond to an area of the light diffractive layer that is substantially covered by both a first area of linear grating structures and a second area of linear grating structures (i.e., where the first area of linear grating structures are crossed by the second area of linear grating structures to create a “grid” of crossed features, at least as seen in a top plan view). In some embodiments, each non-diffractive region of the plurality of spaced-apart non-diffractive regions corresponds to an area of the light diffractive layer that is substantially not covered by either a first area of linear grating structures or a second area of linear grating structures (i.e., has substantially no grating structures).

[0045] In some embodiments of the display system, the plurality of spaced-apart, one-dimensional diffraction regions may include a first plurality of one-dimensional linear gratings aligned along a first film direction and a second plurality of one-dimensional linear gratings aligned along a different, second film direction (i.e., each one-dimensional diffraction region will have linear gratings aligned along either the first film direction or the second film direction, but not both). In some embodiments, the first film direction may be substantially orthogonal to the second film direction. In some such embodiments, each two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions may include a first plurality of one-dimensional linear structures aligned along the first film direction intersecting a second plurality of one-dimensional linear structures aligned along the second film direction, creating a two-dimensional grid, as seen in a top plan view.

[0046] As described elsewhere herein, the one-dimensional diffraction regions and two-dimensional diffraction regions may, in some embodiments, include diffractive features and / or surfaces other than linear gratings, and the description of embodiments including linear gratings is not meant to be limiting in any way.

[0047] In some embodiments of the display system, light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer. In some such embodiments, the exiting light may have a normalized intensity profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer. In some such embodiments, for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the normalized intensity profile may have a normalized peak intensity, and a full width at half maximum (FWHM), such that a ratio of the normalized peak intensity to the FWHM is greater than about 0.007 degrees1, or about 0.008 degrees1, or about 0.009 degrees1, or about 0.01 degrees1, or about 0.02 degrees1, or about 0.03 degrees1, or about 0.04 degrees1, or about 0.05 degrees1.

[0048] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause a full width at half maximum of the normalized intensity profile to decrease by at least a factor of about 10%, or about 20%, or about 30%, or about 50%, or about 60%, or about 70%.

[0049] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause an on-axis intensity of the normalized intensity profile to increase by at least a factor of about 10%, or about 15%, or about 20%, or about 30%, or about 40%, or about 50%, or about 75%, or about 100%, or about 125%, or about 150%. In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause a change in the slope for positive viewing angles of the normalized intensity profile to decrease, as described elsewhere herein.

[0050] According to some aspects of the present description, a light diffractive layer may be configured to be disposed between a viewer and a display region of a display configured to form an image thereacross for viewing by the viewer. In some embodiments, the display region may include a plurality of spaced-apart light-emitting elements separated by one or more light non-emitting regions.

[0051] In some embodiments, the light diffractive layer may include a plurality of spaced-apart non- diffractive regions (i.e., regions substantially devoid of diffractive features) separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two-dimensional diffraction regions. In some embodiments, the non-diffractive regions of the plurality of spaced-apart non-diffractive regions may be configured to be substantially aligned, in a one-to-one relationship with, the light emitting elements of the plurality of light emitting elements of the display region. In some embodiments, at least 80% of the light non-emitting regions of the display region may be covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions.

[0052] In some embodiments, the light diffractive layer may further include a first one-dimensional diffraction sublayer and a second one-dimensional diffraction sublayer. In some embodiments, the first one-dimensional diffraction sublayer may include first areas of linear grating structures aligned along a first direction (e.g., x-direction) and separated by areas without grating structures aligned along the same first direction. In some embodiments, the second one-dimensional diffraction sublayer may include second areas of linear grating structures aligned along a second direction (e.g., y-direction) substantially orthogonal to the first direction and separated by areas without grating structures aligned along the same second direction.

[0053] In some embodiments, each one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffractions regions may correspond to an area of the light diffractive layer that is substantially covered by one of a first area of linear grating structures and a second area of linear grating structures. In some embodiments, each two-dimensional diffraction region of the plurality of spaced- apart, two-dimensional diffraction regions may correspond to an area of the light diffractive layer that is substantially covered by both a first area of linear grating structures and a second area of linear grating structures. In some embodiments, each non-diffractive region of the plurality of spaced-apart non- diffractive regions may correspond to an area of the light diffractive layer that is substantially not covered by either a first area of linear grating structures or a second area of linear grating structures.

[0054] As described elsewhere herein, the one-dimensional diffraction regions and two-dimensional diffraction regions may, in some embodiments, include diffractive features and / or surfaces other than linear gratings, and the description of embodiments including linear gratings is not meant to be limiting in any way.

[0055] In some embodiments of the light diffractive layer, light emitted by the light emitting elements is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer. (It should be noted that at least a portion of the light emitted by the light emitting elements passes through areas of the light diffractive layer without diffractive structures and, as such, is substantially not diffracted. That is, saying the light is “diffractively transmitted” may include some portion of light that is transmitted but not diffracted, along with the light that is both transmitted and diffracted.) In some such embodiments, the exiting light may have a normalized intensity profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer. In some such embodiments, for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the normalized intensity profile may have a normalized peak intensity, and a full width at half maximum (FWHM), such that a ratio of the normalized peak intensity to the FWHM may be greater than about 0.007 degrees1, or about 0.008 degrees1, or about 0.009 degrees1, or about 0.01 degrees1, or about 0.02 degrees1, or about 0.03 degrees1, or about 0.04 degrees1, or about 0.05 degrees1.

[0056] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause a full width at half maximum of the normalized intensity profile to decrease by at least a factor of about 10%, or about 20%, or about 30%, or about 50%, or about 60%, or about 70%.

[0057] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause an on-axis intensity of the normalized intensity profile to increase by at least a factor of about 10%, or about 15%, or about 20%, or about 30%, or about 40%, or about 50%, or about 75%, or about 100%, or about 125%, or about 150%.

[0058] In some embodiments, for at least one wavelength in the visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer may cause a change in the slope for positive viewing angles of the normalized intensity profile to decrease, as described elsewhere herein.

[0059] According to some aspects of the present description, a display system may include a display region comprising a plurality of spaced-apart, light-emitting elements separated by light non-emitting regions, and a light diffractive layer disposed on, and spaced apart along a thickness direction of the display system from, the light emitting elements.

[0060] In some embodiments, the light diffractive layer may include, from a top plan view, a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two-dimensional diffraction regions. In some such embodiments, each non-diffractive region of the plurality of spaced-apart non-diffractive regions may be substantially aligned in a one-to-one relationship with a corresponding light emitting element of the plurality of light emitting elements of the display region. In some embodiments, at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 99%, of the light non-emitting regions of the display region may be covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two- dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions. In some embodiments, light emitted by the light emitting elements may be diffractively transmitted by the light diffractive layer and may exit the display system in air toward a viewer. In some such embodiments, the exiting light may have a normalized intensity profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a linear direction of at least one of the one-dimensional diffraction regions, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the normalized intensity profile has a normalized peak intensity, and a full width at half maximum (FWHM), such that a ratio of the normalized peak intensity to the FWHM may be greater than about 0.007 degrees1, or about 0.008 degrees1, or about 0.009 degrees1, or about 0.01 degrees1, or about 0.02 degrees1, or about 0.03 degrees1, or about 0.04 degrees1, or about 0.05 degrees1.

[0061] In some embodiments of the display system, the light diffractive layer may further include a first one-dimensional diffraction sublayer having first areas of linear grating structures aligned along a first direction (e.g., x-direction) and separated by areas without grating structures aligned along the same first direction, and a second one-dimensional diffraction sublayer having second areas of linear grating structures aligned along a second direction (e.g., y-direction) substantially orthogonal to the first direction and separated by areas without grating structures aligned along the same second direction. In some such embodiments, each one-dimensional diffraction region of the plurality of spaced-apart, one-dimensional diffraction regions may correspond to an area of the light diffractive layer that is substantially covered by one of a first area of linear grating structures and a second area of linear grating structures. In some such embodiments, each two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffractions regions may correspond to an area of the light diffractive layer that is substantially covered by both a first area of linear grating structures and a second area of linear grating structures. In some such embodiments, each non-diffractive region of the plurality of spaced-apart, non-diffractive regions may correspond to an area of the light diffractive layer that is substantially not covered by either a first area of linear grating structures or a second area of linear grating structures.

[0062] As described elsewhere herein, the one-dimensional diffraction regions and two-dimensional diffraction regions may, in some embodiments, include diffractive features and / or surfaces other than linear gratings, and the description of embodiments including linear gratings is not meant to be limiting in any way.

[0063] According to some aspects of the present description, a display system may include a display region and a light diffractive layer. In some such embodiments, the display region may include a plurality of spaced-apart light-emitting elements separated by light non-emitting regions. In some such embodiments, the light diffractive layer may be disposed on, and spaced apart along a thickness direction of the display system from, the light emitting elements. In some embodiments, the light diffractive layer may include, from a top plan view, a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two- dimensional diffraction regions. In some such embodiments, each non-diffractive region of the plurality of spaced-apart, non-diffractive regions may be substantially aligned in a one-to-one relationship with a corresponding light emitting element of the plurality of light emitting elements of the display region.

[0064] In some embodiments, at least 80% of the light non-emitting regions of the display region may be covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two-dimensional diffraction region of the plurality of spaced-apart two- dimensional diffraction regions.

[0065] In some embodiments, light emitted by the light emitting elements may be diffractively transmitted by the light diffractive layer and may exit the display system in air toward a viewer. In some such embodiments, the exiting light may have a normalized intensity profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a linear direction of at least one of the one-dimensional diffraction regions, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes an on-axis intensity of the normalized intensity profile to increase by at least a factor of about 10%, or about 15%, or about 20%, or about 30%, or about 40%, or about 50%, or about 75%, or about 100%, or about 125%, or about 150%.

[0066] In some embodiments of the display system, the light diffractive layer may cause a full width at half maximum of the intensity profile to decrease by at least a factor of about 10%, or about 20%, or about 30%, or about 50%, or about 60%, or about 70%, relative to a comparative display system without the light diffractive layer.

[0067] In some embodiments, the light diffractive layer may further include a first one-dimensional diffraction sublayer and a second one-dimensional diffraction sublayer. In some embodiments, the first one-dimensional diffraction sublayer may include first areas of linear grating structures aligned along a first direction (e.g., x-direction) separated by areas without grating structures aligned along the same first direction, and the second one-dimensional diffraction sublayer may include second areas of linear grating structures aligned along a second direction (e.g., y-direction) substantially orthogonal to the first direction and separated by areas without grating structures aligned along the same second direction.

[0068] In some such embodiments, each one-dimensional diffraction region of the plurality of spaced- apart one-dimensional diffraction region may correspond to an area of the light diffractive layer that is substantially covered by one of a first area of linear grating structures and a second area of linear grating structures. In some such embodiments, each two-dimensional diffraction region of the plurality of spaced- apart two-dimensional diffraction regions may correspond to an area of the light diffractive layer that is substantially covered by both a first area of linear grating structures and a second area of linear grating structures. In some embodiments, each non-diffractive region of the plurality of spaced-apart non- diffractive regions may correspond to an area of the light diffractive layer that is substantially not covered by either a first area of linear grating structures or a second area of linear grating structures.

[0069] As described elsewhere herein, the one-dimensional diffraction regions and two-dimensional diffraction regions may, in some embodiments, include diffractive features and / or surfaces other than linear gratings, and the description of embodiments including linear gratings is not meant to be limiting in any way.

[0070] In some embodiments of the display system, light emitted by the light emitting elements may be diffractively transmitted by the light diffractive layer and may exit the display system in air toward the viewer. In some such embodiments, the exiting light may have a normalized intensity profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes the slope for positive viewing angles of the normalized intensity profile to decrease, as described elsewhere herein.

[0071] Turning now to the figures, FIG. 1A is a top plan view of an embodiment of a display region of a display system, according to the present description. The display region 100 may be part of a display system, such as any of the embodiments of a display system described herein, and may include a light emitting region 50 (e.g., a pattern of light emitting elements such as light emitting diodes may make up the light emitting region 50) and a remaining light non-emitting region 60 (i.e., a region not configured to emit light, such as the regions of display region 100 between light emitting elements / region 50).

[0072] FIG. IB is a top plan view of an embodiment of a first one-dimensional diffraction sublayer of a light diffractive layer of a display system, according to the present description. In some embodiments, the light diffractive layer of some of the embodiments described herein may include a first one-dimensional diffraction sublayer 110, such as that shown in FIG. IB, and a second one-dimensional diffraction sublayer 120, such as that shown in FIG. 2A. In practice, the first and second one-dimensional diffraction layers may each have diffractive features or surfaces (e.g., such as linear gratings, as shown in FIG. IB, or any other appropriate diffractive features / surfaces) which are aligned to different, possibly orthogonal directions of the light diffractive layer. By disposing the first one-dimensional diffraction sublayer on the second one-dimensional diffraction layer, a light diffractive layer may be created which has areas with no diffractive regions, areas with diffractive regions of one direction or the other, and areas with diffractive regions of both directions, crossed to create two-dimensional diffractions regions, as seen from a top plan view.

[0073] Starting first with the first one-dimensional diffraction sublayer 110 of FIG. IB, the first onedimensional diffraction sublayer 110 may include a first light diffractive area 110a (which may include a plurality of smaller sections of linear gratings such as those shown in FIG. IB, or other one-dimensional diffractive features), and a remaining first non-diffractive area 110b (which may also include a plurality of smaller sections without linear gratings or other diffractive features). In the example shown in FIG. IB, the first light diffractive area 110a and the first non-diffractive area 110b are aligned along the y-direction of the light diffractive area (as shown by the coordinate reference in FIG. IB). By comparing the first one-dimensional diffraction sublayer 110 of FIG. IB to the location of the light emitting region / elements 50 of FIG. 1 A, it can be seen that, in general, the first non-diffractive area(s) 110b (i.e., those areas with no linear diffractive features) are substantially aligned with the light emitting region / elements 50 of FIG. 1A.

[0074] Turning now to FIG. 2A, the second one-dimensional diffraction sublayer 120 may similarly include a second light diffractive area 120a (which may include a plurality of smaller sections of linear gratings such as those shown in FIG. 2A, or other diffractive features), and a remaining second non- diffractive area 120b (which may also include a plurality of smaller sections without linear gratings or other diffractive features). In the example shown in FIG. 2A, the second light diffractive area 120a and the second non-diffractive area 120b are aligned along the x-direction of the light diffractive area (as shown by the coordinate reference in FIG. 2A). In the examples of FIGS. IB and 2A, the alignment of the diffractive and non-diffractive areas between the two layers are substantially orthogonal to each other.

[0075] As with the first one-dimensional diffraction sublayer 110 of FIG. IB, by comparing the second one-dimensional diffraction sublayer 120 of FIG. 2A to the location of the light emitting region / elements 50 of FIG. 1 A, it can be seen that, in general, the second non-diffractive area(s) 120b (i.e., those areas with no diffractive features) are substantially aligned with the light emitting region / elements 50 of FIG. 1A (but in the x-direction rather than the y-direction alignment in FIG. IB).

[0076] FIG. 2B shows display system 300, where the first one-dimensional diffraction sublayer 110 and the second one-dimensional diffraction sublayer 120 are disposed such that they are substantially coextensive in length and width with each other and display region 100. It should be noted that the edges of display region 100 are shown slightly offset (toward the left and bottom) in FIG. 2B in order to illustrate that it exists under the first and second one-dimensional diffraction sublayers. In reality, display region 100 would typically be substantially coextensive in length and width with the first and second onedimensional diffraction sublayers and thus would not be visible in this top down (plan) view. Additional views of display system 300, showing the stacking of layers, are provided in the discussions of FIGS. 3A and 3B discussed elsewhere herein.

[0077] Returning to FIG. 2B, it can be seen that the non-diffractive areas 110b of first one-dimensional diffraction sublayer 110 are aligned along the y-direction and the non-diffractive areas 120b of second one-dimensional diffraction sublayer 120 are aligned along the x-direction, such that an overlapping non- diffractive area common to both the first and second one-dimensional diffraction sublayers corresponds to one of the light emitting regions / elements 50. Stated another way, the first 110 and second 120 onedimensional diffraction sublayers are configured such that their overlapping creates non-diffractive areas in the overall light diffractive layer created by the two sublayers.

[0078] Another thing to be noted regarding FIG. 2B is that, by disposing second one-dimensional diffraction sublayer 120 on first one-dimensional diffraction sublayer 110, thus creating a combined light diffractive layer, the resulting light diffractive layer has areas which are one-dimensional diffraction regions 130a aligned along a first direction, other areas which are one-dimensional diffraction regions 130b aligned along a second direction, and still other areas with two-dimensional diffraction regions 130ab which have crossed diffractive features in both of two orthogonal directions (in this example, features in the y-direction and the x-direction crossing to create a grid-like two-dimensional grating 130ab as seen in a top plan view). It is possible to create a light diffractive layer that has a single layer construction, rather than using two crossed layers of diffractive features, as will be discussed elsewhere herein (see, e.g., FIGS. 4A and 4B and the related description).

[0079] FIGS. 3 A and 3B provide alternate side views of an embodiment of display system 300 (such as display system 300 shown in FIG. 2B) which better illustrate the stacked and superimposed first and second one-dimensional diffraction sublayers. FIGS. 3 A and 3B show essentially the same information, differing only in the direction shown in the view (FIG. 3A shows display system 300 as seen looking along the y-direction, and FIG. 3B shows display system 300 as seen looking along the x-direction). FIGS. 3A and 3B should be examined together for the following discussion.

[0080] In the embodiment shown in FIGS. 3A and 3B, light diffractive layer 130 includes first onedimensional diffraction sublayer 110 and second one-dimensional diffraction sublayer 120 disposed adjacent to, and substantially coextensive in length and width with, each other and display region 100. While looking along the y-direction of the light diffractive layer 130 (as shown in FIG. 3 A), the alignment of second one-dimensional diffraction sublayer 120 enables the viewing of both the second diffractive areas 120a and second non-diffractive areas 120b, while the alignment of first one-dimensional diffraction sublayer 110, aligned along the x-direction, does not show the diffractive and non-diffractive areas of that layer. Conversely, while looking along the x-direction of the light diffractive layer 130 (as shown in FIG. 3B), the alignment of first one-dimensional diffraction sublayer 110 now enables the viewing of both the first diffractive areas 110a and first non-diffractive areas 110b, while the alignment of second one-dimensional diffraction sublayer 120, aligned along the y-direction, does not show the diffractive and non-diffractive areas of that layer. In some embodiments, at least one of the first onedimensional diffraction sublayer 110 and second one-dimensional diffraction sublayer 120 may include an optically clear substrate layer 115.

[0081] The side views of FIGS. 3 A and 3B illustrate how the non-diffractive areas 110b and 120b of first one-dimensional diffraction sublayer 110 and second one-dimensional diffraction sublayer 120, respectively, are aligned with one or more of light emitting regions / elements 50 of display region 100, and how non-light emitting regions 60 are substantially covered by one or both of the diffractive areas 110a and 120a of first one-dimensional diffraction sublayer 110 and second one-dimensional diffraction sublayer 120.

[0082] The embodiments described in FIGS. 1A-3B describe a light diffractive layer 130 which includes first and second one-dimensional diffraction sublayers which each have linear gratings that are aligned in different directions to create areas of one-dimensional diffraction regions and two-dimensional diffractions regions (as seen in a top plan view) in the light diffractive area. FIG. 4A is a top plan view of an embodiment of a display system 300a with an alternate light diffraction layer 130a having a plurality of one-dimensional diffraction regions and a plurality of two-dimensional diffraction regions in a singlelayer construction. The embodiment 300a of FIG. 4A (and 4B) shares many elements with other embodiments described herein, and so it is assumed that like-numbered elements serve the same function as previously described unless specifically stated otherwise herein. FIG. 4B provides a side view of the display system of FIG. 4A including the alternate light diffraction layer 130a, and it may be helpful to view both figures together in the following discussion.

[0083] In FIGS. 4A and 4B, light diffractive layer 130a includes a plurality of non-diffractive regions 80 (i.e., regions without grating features) separated by a plurality of spaced-apart one-dimensional linear diffraction regions 70 / 70a / 70b and a plurality of spaced-apart two-dimensional diffraction regions 75. Light diffractive layer 130a is a single layer (as seen in FIG. 4B) and is disposed on display region 100 such that the non-diffractive regions 80 are substantially aligned in a one-to-one correspondence with the light emitting regions / elements 50 of display region 100. In some embodiments, some of the onedimensional diffraction regions 70 / 70a may be aligned along a first direction of the light diffractive layer (e.g., along the x-direction shown in FIG. 4A) and some of the one-dimensional diffraction regions 70 / 70b may be aligned along a different, second direction of the light diffractive layer (e.g., along the y- direction shown in FIG. 4A). In other embodiments, all of the one-dimensional diffraction regions 70 may be aligned along a same direction. In some embodiments, each of the two-dimensional diffraction regions 75 may have diffractive features aligned along both a first direction and a second direction, crossing to create a grid-like structure, as seen in a top plan view. In some embodiments, the first direction and the second direction may be substantially orthogonal.

[0084] Stated another way, in some embodiments, each non-diffractive region 80 of at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, of the non-diffractive regions 80 of the plurality of spaced-apart non-diffractive regions may be substantially aligned in a one-to-one relationship with a corresponding light emitting element 50 of the plurality of light emitting elements. In some embodiments, at least 80% of the remaining light non-emitting region 60 on display region 100 may be covered by one of a one-dimensional diffraction region 70a / 70b of the plurality of spaced-apart onedimensional diffraction regions 70 and a two-dimensional diffraction region 75 of the plurality of spaced- apart two-dimensional diffraction regions 75.

[0085] FIG. 4B shows a side view of display system 300a, illustrating how light diffractive layer 130a is a single layer which may, in some embodiments, include a substrate layer 115. Dashed lines are shown in FIG. 4B to show how non-diffractive areas 80 of light diffractive layer 130a align with light emitting elements 50 (in this side view of FIG. 4B, non-diffractive areas 80 are not visible from the edge view shown but provide a substantially optically clear opening through light diffractive layer 130a above and substantially aligned with each light emitting element 50.

[0086] FIG. 5 is a side view of an embodiment of a display system (such as any of the embodiments of display system 300 described herein) showing how light may be diffractively transmitted by a one- dimensional diffraction layer (or example, a diffraction layer with linear gratings or other, similar directional diffractive features). A display region 100 may include a light emitting region 50 which may include the sum of the light emitting regions emitted by a plurality of light emitting elements 50 (e.g., light emitting diodes). Light emitting regions / elements 50 may be separated from each other by one or more non-light-emitting regions 60 (e.g., areas which do not have light-emitting elements).

[0087] A light diffractive layer 200 may include one or more areas of diffractive features 90. These diffractive features 90 may be, for example, any of the diffractive features described elsewhere herein. When light rays 160 are transmitted by any of the light emitting regions 50, they may be transmitted as part of a light cone where central light rays 160 (those rays corresponding substantially to a non- diffractive area 92 in light diffractive layer 200) are transmitted substantially unchanged as transmitted light rays 160’. In some embodiments, some of the outer rays 160 of the emitted light cone may be emitted at an oblique angle to the light diffractive layer 200 and may therefore pass through the diffractive features 90. The diffractive features 90 may diffract incoming light rays 160 and transmit them as redirected light rays 162. In some embodiments, redirected light rays 162 may be substantially orthogonal to light diffractive layer 200, or may at least be closer to “on axis” (close to orthogonal to light diffractive layer 200).

[0088] Finally, FIG. 6 is a plot of normalized luminance values versus polar viewing angle of example embodiments of a display system and a comparative example display system, according to the present description. Luminance profiles are provided for four different display systems. The “Control” display system, plotted with the solid line, shows a typical luminance profile for a display system which does not use a light diffractive layer as described herein. It should be noted that the display values have been normalized based on the maximum luminance seen for the control film at a zero-degree viewing profile has a value of 1 (so the y-axis does not have units), and all other plots have been normalized to show the comparative performance.

[0089] As can be seen by the “Control” plot, the control display system actually has its highest luminance values at around ±65 degrees, where the normalized luminance value is about 1.3. This gives the control plot a “saddle” shaped appearance, where the peak luminance is not on-axis (zero degrees) but far off-axis. In this situation, the slope SI of the plot line for positive viewing angles is positive (values increase from a zero-degree viewing angle toward the peak luminance around about +65 degrees). There are certainly applications where this saddle performance would not be the most desirable, and having an on-axis peak transmission, with a decreased slope for positive viewing angles, would be desirable.

[0090] The remaining three plot lines show the performance of display systems using an embodiment of the light diffractive layers described herein, disposed between the display region and the eye of an observer / viewer. The grating features on the light diffractive layer can be configured to provide varying levels of axial luminance gain (on-axis gain). Plots are provided for a “low gain”, “medium gain”, and “high gain” light diffractive layer. As can be seen, even the “low gain” light diffractive layer has a peak value, PL, at a zero-degree viewing angle that is nearly 1.8 times that of the peak value, Pi, of the control film. Each of the light diffractive layer display systems also demonstrates a negative slope (such as slope S2) for luminance values starting from a zero-degree viewing angle and for increasing viewing angles. Stated another way, the peak transmission for each of the light diffractive layer display systems occurs on-axis, at a zerodegree viewing angle, rather than at a significantly higher off-axis viewing angle. Another characteristic seen by each of the light diffractive layer display systems is that the full width at half maximum, or FWHM, may be significantly decreased for these display systems. In some embodiments, the presence of the light diffractive layer in the display system may cause the FWHM to reduce by at least about 10%. In the example of the FWHM of the control display system compared to the FWHM of the high-gain display system, the decrease is nearly 70%.

[0091] For example, the high-gain display system has a peak luminance PH that is nearly 2.4 times greater than Pi, and the FWHM is about 50 degrees, versus and FWHM of about 160 degrees for the control film. The medium-gain display system has a peak luminance PM that is about 2.12 times greater than Pi, and an FWHM is about 76 degrees (versus an FWHM of about 160 degrees for the control film). The low-gain display system has a peak luminance P that is about 1.8 times greater than Pi, and an FWHM is about 150 degrees (versus an FWHM of about 160 degrees for the control film).

[0092] The ratio of the peak luminance on the normalized intensity profile to the FWHM, can be used as an indicator of performance for the display systems described herein. In some embodiments, for example, this ratio of normalized peak intensity to FWHM may be greater than about 0.007 degrees1, or about 0.008 degrees1, or about 0.009 degrees1, or about 0.01 degrees1, or about 0.02 degrees1, or about 0.03 degrees1, or about 0.04 degrees1, or about 0.05 degrees1. For example, the ratio of PH of the high-gain display system of FIG. 6 to its FWHM is approximately (2.4 / 50) = 0.048. The ratio PL of the low-gain display system to its FWHM is approximately (1.8 / 150) = 0.012.

[0093] 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.

[0094] Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially equal” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially equal” will mean about equal where about is as described above. If the use of “substantially parallel” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially parallel” will mean within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees, or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of “substantially aligned” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially aligned” will mean aligned to within 20% of a width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned to within 10% or to within 5% of a width of the objects being aligned.

[0095] 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.

[0096] Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed:

1. A display system comprising: a display region configured to form an image thereacross for viewing by a viewer and comprising a light emitting region configured to emit light and leaving a remaining 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, the light diffractive layer comprising a first one-dimensional diffraction sublayer and a second one-dimensional diffraction sublayer disposed on, and substantially coextensive in length and width with, the first one-dimensional diffraction sublayer; the first one-dimensional diffraction sublayer comprising a first light diffractive area leaving a remaining first non-diffractive area, and the second one-dimensional diffraction sublayer comprising a second light diffractive area leaving a remaining second non-diffractive area; wherein a first portion of the light non-emitting region is covered by the first light diffractive area of the first one-dimensional diffraction sublayer but not by the second light diffractive area of the second one-dimensional diffraction sublayer, a second portion of the light non-emitting region, different from the first portion, is covered by the second light diffractive area of the second one-dimensional diffraction sublayer but not by the first light diffractive area of the first one-dimensional diffraction sublayer, a third portion of the light non-emitting region, different from the first portion and the second portion, is covered by both the first light diffractive area of the first one-dimensional diffraction sublayer and the second light diffractive area of the second one-dimensional diffraction sublayer so that at least 80% of the light non-emitting region is covered by at least one of the first and second diffractive areas, and at least 80% of the light emitting region is not covered by either the first light diffractive area of the first one-dimensional diffraction sublayer or the second light diffractive area of the second onedimensional diffraction sublayer.

2. The display system of claim 1, wherein the first light diffractive area of the first one-dimensional diffraction sublayer comprises linear gratings aligned along a first direction, and the second light diffractive area of the second one-dimensional diffraction sublayer comprises linear gratings aligned along a different, second direction.

3. The display system of claim 2, wherein the first direction and the second direction are substantially orthogonal to each other.

4. The display system of claim 1, wherein the first light diffractive area of the first one-dimensional diffraction sublayer comprises diffractive features aligned along a first direction, and the second light diffractive area of the second one-dimensional diffraction sublayer comprises diffractive features aligned along a different, second direction; wherein the diffractive features aligned along the first direction and the second direction comprise one or more of phase gratings, amplitude gratings, one-dimensional gratings, two-dimensional gratings, subwavelength structures, and metasurface structures.

5. The display system of claim 1, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the normalized luminance profile has a normalized peak luminance, and a full width at half maximum (FWHM), a ratio of the normalized peak luminance to the FWHM being greater than about 0.007 degrees' i6. The display system of claim 1, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes a full width at half maximum of the normalized luminance profile to decrease by at least a factor of 10%.

7. The display system of claim 1, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes an on-axis luminance of the normalized luminance profile to increase by at least a factor of 10%.

8. The display system of claim 1, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such thatfor at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes a slope for positive viewing angles of the normalized luminance profile to decrease.

9. A display system comprising: a display region configured to form an image thereacross for viewing by a viewer and comprising a plurality of light emitting elements defining, in combination, a light emitting region configured to emit light and leaving a remaining 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, the light diffractive layer comprising a plurality of spaced-apart non-diffractive regions separated by a plurality of spaced-apart one-dimensional diffraction regions and a plurality of spaced-apart two- dimensional diffraction regions.

10. The display system of claim 9, wherein each non-diffractive region of at least 50% of the non- diffractive regions of the plurality of spaced-apart non-diffractive regions is substantially aligned in a one- to-one relationship with a corresponding light emitting element of the plurality of light emitting elements, and at least 80% of the remaining light non-emitting region is covered by one of a one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions and a two- dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions.

11. The display system of claim 9, wherein no more than 20% of the light emitting region is covered by either a one-dimensional linear diffraction region or a two-dimensional diffraction region.

12. The display system of claim 9, wherein the light diffractive layer comprises a first onedimensional diffraction sublayer comprising first areas of linear grating structures aligned along a first direction and separated by areas without grating structures aligned along the same first direction, and a second one-dimensional diffraction layer comprising second areas of linear grating structures aligned along a second direction substantially orthogonal to the first direction and separated by areas without grating structures aligned along the same second direction; wherein each one-dimensional diffraction region of the plurality of spaced-apart one-dimensional diffraction regions corresponds to an area of the light diffractive layer that is substantially covered by one of a first area of linear grating structures and a second area of linear grating structures,wherein each two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions corresponds to an area of the light diffractive layer that is substantially covered by both a first area of linear grating structures and a second area of linear grating structures, and wherein each non-diffractive region of the plurality of spaced-apart non-diffractive regions corresponds to an area of the light diffractive layer that is substantially not covered by either a first area of linear grating structures or a second area of linear grating structures.

13. The display system of claim 9, wherein the plurality of spaced-apart one-dimensional diffraction regions comprise a first plurality of one-dimensional linear gratings aligned along a first film direction and a second plurality of one-dimensional linear gratings aligned along a different, second film direction.

14. The display system of claim 9, wherein the first film direction is substantially orthogonal to the second film direction.

15. The display system of claim 13, wherein each two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions comprises a first plurality of one-dimensional linear structures aligned along the first film direction intersecting a second plurality of one-dimensional linear structures aligned along the second film direction, creating a two-dimensional grid as seen from a top plan view.

16. The display system of claim 9, wherein the plurality of spaced-apart one-dimensional diffraction regions comprise a first plurality of one-dimensional diffractive features aligned along a first film direction and a second plurality of one-dimensional diffractive features aligned along a different, second film direction, and each two-dimensional diffraction region of the plurality of spaced-apart two-dimensional diffraction regions comprises a first plurality of one-dimensional diffractive features aligned along the first film direction intersecting a second plurality of one-dimensional diffractive structures aligned along the second film direction, creating a two-dimensional grid as seen from a top plan view; wherein the diffractive features aligned along the first direction and the second direction comprise one or more of phase gratings, amplitude gratings, one-dimensional gratings, two-dimensional gratings, subwavelength structures, and metasurface structures.

17. The display system of claim 9, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm,the normalized luminance profile has a normalized peak luminance, and a full width at half maximum (FWHM), a ratio of the normalized peak luminance to the FWHM being greater than about 0.007 degrees' i18. The display system of claim 9, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes an on-axis luminance of the normalized luminance profile to increase by at least a factor of 10%.

19. The display system of claim 9, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes a full width at half maximum of the normalized luminance profile to decrease by at least a factor of 10%.

20. The display system of claim 9, wherein light emitted by the light emitting region is diffractively transmitted by the light diffractive layer and exits the display system in air toward the viewer, the exiting light having a normalized luminance profile as a function of light propagation angle in a first plane that is parallel to the thickness direction and orthogonal to a major surface of the light diffractive layer, such that for at least one wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the light diffractive layer causes a slope for positive viewing angles of the normalized luminance profile to decrease.

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