WO2024049695A1

WO2024049695A1 - Reflector with engineered light collection and reflection angles

Info

Publication number: WO2024049695A1
Application number: PCT/US2023/031008
Authority: WO
Inventors: Shenping Li
Original assignee: Corning Incorporated
Priority date: 2022-09-02
Filing date: 2023-08-24
Publication date: 2024-03-07
Also published as: TW202417953A

Abstract

A reflective liquid crystal display (RLCD) is provided. The RLCD includes a base surface, one or more first reflector units, and one or more second reflector units. Each first reflector unit defines a first reflection surface, and each first reflector unit is positioned on the base surface so that each first reflection surface defines a downward slope in a first orientation direction. Each second reflector unit defines a second reflection surface, and each second reflector unit is positioned on the base surface so that each second reflection surface defines a downward slope in a second orientation direction. The first orientation direction is perpendicular to the second orientation direction.

Description

REFLECTOR WITH ENGINEERED LIGHT COLLECTION AND REFLECTION

ANGLES

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 63/403331 filed on September 2, 2022, the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] Embodiments of the present invention relate generally to reflector designs for a reflective liquid crystal display (RLCD).

BACKGROUND OF THE INVENTION

[0003] RLCDs have lower energy consumption relative to other displays, and this makes RLCDs desirable for certain uses. RLCDs are used in various applications, including mobile phones, e-readers, retail display tabs/labels, information displays, and public signage. RLCDs are often provided without any backlight unit, and the efficiency and image brightness of an RLCD will typically be tied to the design of reflectors in the RLCD and how the reflectors collect and reflect incoming light.

[0004] In the past, two approaches have been used to control the reflected light in RLCDs. Under a first approach, an isotropic in-cell reflector (IICR) is used. This IICR is a “bump”-like reflective texture made by photo lithography inside of the liquid crystal display (LCD) cell. Under a second approach, light controlling film (LCF) is used. This LCF is an index/birefringent gradient film that is used to guide light. When applied, neither one of these options gives satisfactory performance. For IICR, photo lithography and the following etching gives symmetric reflective textures (e.g. semi-spherical), and no control of reflector surface curvature is possible. Thus, limited light collection and reflection efficiencies can be achieved with IICR. For LCF, a parallax problem is created as laminated film is provided outside of the RLCD front glass and polarizer. In addition, LCF introduces birefringence and lowers the contrast ratio (CR) of the RLCD.

BRIEF SUMMARY OF THE INVENTION

[0005] Various embodiments provided herein relate to RLCDs having an improved design. Reflector units are provided that may be optimized to provide high efficiencies of light collection and reflection for a defined use case. The reflector units may be provided within the RLCD to provide more uniform light reflection in angle space. Further, the reflector units may be suitable for microreplication fabrication, making it more cost effective to manufacture the reflector units.

[0006] Reflectors may be provided having reflector units, and the specific design of a reflector and the reflector units therein may be optimized to meet the needs of a particular use case. Reflector units may be provided having identical geometries in some embodiments, but the geometries for reflector units may be different in other embodiments, with the sizes and/or base shapes of reflector units being different in other embodiments. Further, the reflector units may be oriented with the same or with different unit orientations.

[0007] Depending on the number of reading orientations that are necessary for a particular use case, an appropriate reflector design may be obtained. For a reflector design of an RLCD with N different reading orientations being required, each reflector should have reflector units oriented in N different unit orientations. For example, where a particular use case requires four different reading orientations, reflector units may be provided in the reflector with four different unit orientations. Reflector units may be positioned with unit orientations that are, for example, perpendicular to each other, opposite from each other, etc., and this may allow for further optimization of a reflector for a particular use case.

[0008] Reflector units may be organized in reflector blocks, and these reflector blocks may be tessellated across an available coverage area so that, for example, the available coverage area is completely covered. Furthermore, where a reflector includes reflector units having different orientation directions, a reflector block may include reflector units having each of the different orientation directions that are used in the reflector. In other words, each of the different orientation directions are represented in a single reflector block. In this way, the reflector blocks may remain uniform across the display. Furthermore, the size of a given reflector block should be less than or equal to the size of a single pixel within the display. In this regard, by specifically arranging the reflector units and controlling the reflector block(s) relative to the pixels, uniformity may be maintained from pixel to pixel.

[0009] To maximize light collection and reflection efficiencies, the number of different unit orientations in a reflector design may preferably be the same as the number of different reading orientations required for a particular use case. Further, the light collection and reflection efficiencies of a reflector are proportional to the effective reflection surface area of the reflector. Thus, the reflector and the reflector units therein may be designed to cover the available surface area to maximize the light collection and reflection efficiencies of a reflector. [0010] In an example embodiment, a reflective liquid crystal display (RLCD) is provided. The RLCD includes a base surface, one or more first reflector units, and one or more second reflector units. Each first reflector unit of the first reflector unit(s) defines a first reflection surface, and each first reflector unit of the first reflector unit(s) is positioned on the base surface so that each first reflection surface of the first reflector unit(s) defines a downward slope in a first orientation direction. Each second reflector unit of the second reflector unit(s) defines a second reflection surface, and each second reflector unit of the second reflector unit(s) is positioned on the base surface so that each second reflection surface of the second reflector unit(s) defines a downward slope in a second orientation direction. The first orientation direction is perpendicular to the second orientation direction.

[0011] In some embodiments, the first reflector unit(s) may cover a first coverage area, the second reflector unit(s) may cover a second coverage area, and the first coverage area may be greater than the second coverage area. In some embodiments, each first reflector unit of the first reflector unit(s) and each second reflector unit of the second reflector unit(s) may be geometrically identical, and each first reflector unit of the first reflector unit(s) may be positioned on the base surface in a different orientation than each second reflector unit of the second reflector unit(s).

[0012] In some embodiments, the base surface may define a coverage area, and the first reflector unit(s) and the second reflector unit(s) may cover the coverage area entirely. Additionally, in some embodiments, each first reflector unit of the first reflector unit(s) and each of second reflector unit of the second reflector unit(s) may define a base having a base shape. A first group of reflector units comprises at least one of the one or more first reflector units or the one or more second reflector units. Each reflector unit of the first group of reflector units defines a first base shape. A second group of reflector units comprises at least one of the one or more first reflector units or the one or more second reflector units. Each reflector unit of the second group of reflector units defines a second base shape. The second base shape is different than the first base shape. Furthermore, in some embodiments, the first group of reflector units may include a first reflector unit of the first reflector unit(s) and a second reflector unit of the second reflector unit(s). In some embodiments, the base shape may be selected from the group consisting of a triangle, a rectangle, a square, a pentagon, a hexagon, and another polygonal shape.

[0013] In some embodiments, a reflector block may include a first reflector unit of the first reflector unit(s) and a second reflector unit of the second reflector unit(s). Furthermore, in some embodiments, the reflector block may define a reflector block base shape, the base surface may define a coverage area, and the reflector block base shape may be tessellated to cover all of the coverage area. Additionally, in some embodiments, the reflector block may cover a reflector block coverage area, and the reflector block coverage area may be less than an area of a pixel. [0014] In some embodiments, each first reflection surface of the first reflector unit(s) and each second reflection surface of the second reflector unit(s) may define a curvature. Additionally, in some embodiments, the curvature may be three-dimensional. Additionally, in some embodiments, the curvature may be radially curved, parabolically curved, asymmetrically curved, polygonally curved, or includes a sine curvature.

[0015] In some embodiments, the RLCD may also include one or more third reflector unit. Each third reflector unit of the third reflector unit(s) may define a third reflection surface. Further, each third reflector unit of the third reflector unit(s) may be positioned on the base surface so that each third reflection surface of the third reflector unit(s) defines a downward slope in a third orientation direction. The third orientation direction may be different from the first orientation direction and the second orientation direction. Additionally, in some embodiments, the RLCD may also include one or more fourth reflector unit. Each fourth reflector unit of the fourth reflector unit(s) may define a fourth reflection surface. Further, each fourth reflector unit of the fourth reflector unit(s) may be positioned on the base surface so that each fourth reflection surface of the fourth reflector unit(s) defines a downward slope in a fourth orientation direction. The fourth orientation direction may be different from the first orientation direction, the second orientation direction, and the third orientation direction. Furthermore, in some embodiments, the first reflection surface or the second reflection surface may possess a smooth finish. In some embodiments, the first reflection surface or the second reflection surface may possess a roughened finish.

[0016] In another example embodiment, reflective liquid crystal display (RLCD) is provided. The RLCD includes a base surface, one or more first reflector units, and one or more second reflector units. Each first reflector unit of the first reflector unit(s) defines a first reflection surface and a first base, and each first reflector unit of the first reflector unit(s) is positioned on the base surface so that each first reflection surface of the first reflector unit(s) defines a downward slope in a first orientation direction. Further, each first base of the first reflector unit(s) has a first base shape. Each second reflector unit of the second reflector unit(s) defines a second reflection surface and a second base, and each second reflector unit of the second reflector unit(s) is positioned on the base surface so that each second reflection surface of the second reflector unit(s) defines a downward slope in a second orientation direction. Further, each second base of the second reflector unit(s) has a second base shape, and the first base shape is different from the second base shape.

[0017] In another example embodiment, a reflective liquid crystal display (RLCD) is provided. The RLCD includes a base surface, one or more first reflector units, and one or more second reflector units. Each first reflector unit of the first reflector unit(s) defines a first reflection surface, and each first reflector unit of the first reflector unit(s) is positioned on the base surface so that each first reflection surface of the first reflector unit(s) defines a downward slope in a first orientation direction. Further, each first reflection surface of the first reflector unit(s) is curved and defines a first curvature. Each second reflector unit of the second reflector unit(s) defines a second reflection surface, and each second reflector unit of the second reflector unit(s) is positioned on the base surface so that each second reflection surface of the second reflector unit(s) defines a downward slope in a second orientation direction. Each second reflection surface of the second reflector unit(s) is curved and defines a second curvature. Further, the first orientation direction is different from the second orientation direction, and the first curvature is different from the second curvature.

[0018] In another example embodiment, a reflective liquid crystal display (RLCD) is provided. The RLCD includes a base surface and reflector units. Each reflector unit of the reflector units defines a reflection surface, and the reflector units are positioned on the base surface so that each reflection surface of the reflector units defines a downward slope in an orientation direction. The base surface defines a coverage area, and the reflector units cover the coverage area entirely. In some embodiments, the RLCD may also include reflector blocks. The reflector blocks may include multiple reflector units having different orientation directions, and the reflector blocks may be tessellated to cover the coverage area entirely.

[0019] In another example embodiment, a reflective liquid crystal display (RLCD) is provided. The RLCD includes a base surface, a plurality of pixels, and a plurality of reflector blocks. Each reflector block of the plurality of reflector blocks includes one or more first reflector units and one or more second reflector units. Each first reflector unit of the first reflector unit(s) defines a first reflection surface, and each first reflector unit of the first reflector unit(s) is positioned on the base surface so that each first reflection surface of the first reflector unit(s) defines a downward slope in a first orientation direction. Each second reflector unit of the second reflector unit(s) defines a second reflection surface, and each second reflector unit of the second reflector unit(s) is positioned on the base surface so that each second reflection surface of the second reflector unit(s) defines a downward slope in a second orientation direction. Each pixel of the plurality of pixels includes at least one reflector block. [0020] In some embodiments, each reflector block of the plurality of reflector blocks may also include one or more third reflector units and one or more fourth reflector units. Each third reflector unit of the third reflector unit(s) may define a third reflection surface, and each third reflector unit of the third reflector unit(s) may be positioned on the base surface so that each third reflection surface of the third reflector unit(s) may define a downward slope in a third orientation direction. Each fourth reflector unit of the fourth reflector unit(s) may define a fourth reflection surface, and each fourth reflector unit of the fourth reflector unit(s) may be positioned on the base surface so that each fourth reflection surface of the fourth reflector unit(s) may define a downward slope in a fourth orientation direction. The first orientation direction, the second orientation direction, the third orientation direction, and the fourth orientation direction may each be different. Additionally, in some embodiments, at least 1.5 reflector blocks may be provided in each pixel of the plurality of pixels. Furthermore, in some embodiments, at least 2 reflector blocks may be provided in each pixel of the plurality of pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0022] FIG. 1 A-1D are schematic views illustrating example displays provided in different orientations, in accordance with some embodiments discussed herein;

[0023] FIG. IE is another schematic view illustrating an example reflector unit and the reflection of reflected light off of the reflector unit, in accordance with some embodiments discussed herein;

[0024] FIG. 2A is a perspective view illustrating an example reflector unit having a flat reflection surface, in accordance with some embodiments discussed herein;

[0025] FIG. 2B is a perspective view illustrating an example reflector unit having a curved reflection surface, in accordance with some embodiments discussed herein;

[0026] FIG. 2C is a cross-sectional view illustrating the example reflector unit of FIG. 2C, in accordance with some embodiments discussed herein;

[0027] FIG. 2D is a cross-sectional view illustrating an example reflector unit having a polygonally curved reflection surface formed by several flat surfaces, in accordance with some embodiments discussed herein;

[0028] FIG. 3 is a bottom view illustrating various example reflector units having different base shapes, in accordance with some embodiments discussed herein; [0029] FIG. 4A-4D are schematic views illustrating reflectors having a plurality of reflector units that are tessellated about an available coverage area, in accordance with some embodiments discussed herein;

[0030] FIG. 5A-5C are schematic views illustrating reflectors having a plurality of reflector units that are tessellated about an available coverage area, in accordance with some embodiments discussed herein;

[0031] FIG. 6A is a schematic view illustrating a reflector having a plurality of reflector units that are tessellated about an available coverage area, in accordance with some embodiments discussed herein;

[0032] FIGS. 6B-6C are schematic views illustrating reflectors having a plurality of reflector units that are tessellated about an available coverage area, in accordance with some embodiments discussed herein;

[0033] FIG. 7A is a perspective view illustrating a reflector with a plurality of reflector units having rectangular base shapes and curved reflection surfaces, in accordance with some embodiments discussed herein;

[0034] FIG. 7B is an enhanced perspective view illustrating a reflector unit of FIG. 7A, in accordance with some embodiments discussed herein;

[0035] FIG. 8 is a schematic cross-sectional view illustrating two reflector units having a curved reflection surface, in accordance with some embodiments discussed herein;

[0036] FIG. 9 is a graph illustrating example radiance in angle space values for a reflector unit, in accordance with some embodiments discussed herein;

[0037] FIGS. 10A-10C are graphs illustrating example angular distributions for reflected light for different reflector units, in accordance with some embodiments discussed herein;

[0038] FIG. 11A is a graph illustrating normalized reflective light power and angular distribution of reflective light in a vertical direction that is obtained for various reflector units having different structure widths, in accordance with some embodiments discussed herein;

[0039] FIG. 1 IB is a graph illustrating normalized reflective light power and angular distribution of reflective light in a horizontal direction that is obtained for various reflector units having different structure widths, in accordance with some embodiments discussed herein;

[0040] FIG. 12A is a schematic view illustrating an example light collection angle off of a display, in accordance with some embodiments discussed herein; [0041] FIG. 12B is a graph illustrating the reflection efficiency and the detector light collection cone angle for various reflector units having different sizes, in accordance with some embodiments discussed herein; and

[0042] FIG. 13 is a front view illustrating an example display having a plurality of pixels, in accordance with some embodiments discussed herein.

DETAILED DESCRIPTION

[0043] Example embodiments of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals generally refer to like elements throughout. For example, reference numerals 222, 422A, 422B, 522A, 522A”, and 622A’ are each intended to refer to a reflector unit.

[0044] FIG. 1A-1D are schematic views illustrating example displays 100 provided in different orientations. FIGS. 1A-1D illustrate typical reading cases of an RLCD using a spherical coordinate system. Looking first at FIG. 1 A, a display 100 is illustrated. The display 100 permits ambient light 104 to be reflected to form reflected light 106, and the reflected light 106 may be projected towards a viewer 102. As shown in FIGS. 1 A-1D, the display 100 may receive ambient light 104 from a different angle depending on the location of the light source (e.g., ceiling, wall, direct light, etc.) providing the ambient light 104 relative to the display 100, and the display 100 may be rotated so that it works in different orientations. For example, in FIG. 1A, the display 100 is oriented in a landscape orientation with the reference point 110 provided towards the right. In FIG. IB, the display 100 is oriented in a portrait orientation with the reference point 110 provided towards the bottom of the display 100. As a further example, in FIG. 1C, the display 100 is oriented in a landscape orientation with the reference point 110 provided towards the left part of the display 100. Additionally, in the example of FIG. ID, the display 100 is oriented in a portrait orientation with the reference point 110 provided towards the top of the display 100. In each example illustrated in FIG. 1 A-1D, the orientation direction 108 of reflector units in the display 100 is directed upwardly so that the ambient light 104 may be reflected at a proper angle so that reflected light 106 is directed to the viewer 102. Reflector units and their orientation directions are discussed further herein. [0045] In FIGS. 1 A-1D, the ambient light 104 may be reflected off of reflector units in the display by a first reflection angle (9) to form reflected light 106. Furthermore, the reflected light 106 may extend in the X-Y plane and the incident ambient light plane, and a second reflection angle (co) may separate the X-axis from the reflected light 106. Ambient light 104 may be received with a collection solid angle space. In general, the efficiency of light collection of a reflector is inversely proportional to the collection solid angle space of the reflector, and the use efficiency of ambient light by a reflector is inversely proportional to the collection solid angle space of the reflector. Thus, the design of reflectors within the display should be optimized based on the typical use cases for the RLCD to enable the most efficient use of the ambient light while still meeting the necessary requirements for a given display. Notably, in various example embodiments, the design may be optimized by changing the geometry of reflector units that are provided in a reflector. For example, a base shape, a reflection surface curvature, a surface slope angle, or a reflector unit size, may be changed to optimize the light properties. Additionally or alternatively, the number of different orientation directions for reflector units in a reflector may be changed. However, the design may be optimized in a variety of other ways.

[0046] FIG. IE provides further detail regarding the operation of reflector units and how light is reflected therefrom. The reflector unit 122 may possess a slope angle (a). Ambient light 104 may be directed towards the reflector unit 122 with a vertical center incident angle (0_C) and a horizontal center incident angle. The reflector unit 122 may be configured so that ambient light 104 is reflected to form reflected light 106 and so that the reflected light 106 is directed towards a viewer 102. By way of non-limiting example, the vertical center incident angle (0_C) may be 30 degrees, and the slope angle (a) may be approximately 15 degrees to cause reflected light to be directed upwardly towards the viewer 102. The ambient light 104 may be directed towards the reflector unit with a horizontal center incident angle. This horizontal center incident angle may be zero degrees, and the reflector unit 122 may be configured so that it will not alter the horizontal direction of reflected light relative to the ambient light. In other words, the vectors for ambient light and reflected light strictly travel in the plane illustrated in FIG. IE — the vectors do not have any horizontal components moving into or out of the page in FIG. IE.

[0047] Example reflector units are illustrated in FIG. 2A and 2B. FIG. 2A is a perspective view illustrating an example reflector unit 222 having a flat reflection surface 212. The reflector unit 222 may define a first orientation direction, and this first orientation direction is directed towards the bottom left in FIG. 2 A. The reflector unit 222 may have a base 214 having a rectangular shape. The base 214 may have a base horizontal width (Wh) and a base vertical width (W_v). The base horizontal width (Wh) may take a wide variety of values. For example, the base horizontal width (Wh) may be between 5 micrometers and 100 micrometers, between 10 micrometers and 50 micrometers, approximately 14.4 micrometers, approximately 21.6 micrometers, or approximately 28.8 micrometers. However, other values could be used for the base horizontal width (Wh). Further, the base vertical width (W_v) may also take a wide variety of values. For example, the base vertical width (W_v) may be between 5 micrometers and 100 micrometers, between 10 micrometers and 50 micrometers, or approximately 24.3 micrometers. However, other values could be used for the base vertical width (W_v). In some embodiments, it may be beneficial for the base horizontal width (Wh) and the base vertical width (W_v) to be small enough so that the horizontal width and the vertical width of reflector blocks are less than the size of a pixel. Reflected light 106 may be provided with angular distributions through scattering by roughening the reflection surface.

[0048] Furthermore, the reflector unit 222 may also possess a back wall 216, and the back wall 216 may define a back wall angle (P) and a height (H). The back wall angle (P) may be defined as the angle between the base 214 and the back wall 216. The height (H) may be the maximum height of the back wall 216. The base horizontal width (Wh), the base vertical width (W_v), the height (H), and other parameters may be varied to obtain the desired performance characteristics for the reflector unit 222 and to maximize a number of reflector units in the available coverage area. The back wall angle (P) may be 90 degrees in some embodiments, between 75 and 95 degrees in some embodiments, between 80 degrees and 90 degrees in some embodiments, or approximately 85 degrees in some embodiments. However, a wide variety of back wall angles (P) may be used, and this may be beneficial to permit the reflector unit 222 to be manufactured with lower tolerances for the back wall angles (P). Furthermore, the reflection surface 212 may define a downward slope in a first orientation direction, and this downward slope may define a reflection surface slope angle (a). The reflection surface slope angle (a) may be defined as the angle between the base 214 and the reflection surface 212. This reflection slope angle (a) may take a wide variety of values. For example, the reflection slope angle (a) may range from five degrees to fifty degrees, from five degrees to thirty degrees, from five degrees to twenty degrees, etc. In the illustrated embodiment, the reflection slope angle (a) is approximately 9.5 degrees.

[0049] FIG. 2B is a perspective view illustrating another example reflector unit 222A having a curved reflection surface 212A. The curved reflection surface 212A may still define a downward slope having a reflection surface slope angle (a) similar to the reflection surface 212 of FIG. 2A. The curved reflection surface 212A may possess a vertical centerline 213 A, and the curved reflection surface 212A may define a certain curvature along the vertical centerline 213 A. In the illustrated embodiment, the curvature along the vertical centerline 213 A is radial so that a vertical radius of curvature (R_v) is defined. Additionally, the curved reflection surface 212A may possess a horizontal centerline 213B, and the curved reflection surface 212A may define a certain curvature along the horizontal centerline 213B. In the illustrated embodiment, the curvature along the horizontal centerline 213B is radial so that a horizontal radius of curvature (Rh) is defined. However, in other embodiments, the curvature along the vertical centerline 213 A and the horizontal centerline 213B may take other forms such as a parabolic curvature, a sine curvature, or some other curvature. Further, the curvature may generally possess a radial curvature in most locations and may depart from a radial curvature near the edges of the curved reflection surface 212A. The reflector unit 222A may also define a back wall 216A. While the back wall 216A may have a reduced height in certain areas due to the curvature in the curved reflection surface 212A, the back wall 216A may be similar to the back wall 216 of FIG. 2 A in other respects. The reflector units 222, 222 A of FIGS. 2A-2B may be small-format reflector units.

[0050] An appropriate reflector unit 222, 222A may be selected to meet the needs of a given use case. For example, a reflector unit may be selected having a flat reflection surface or a curved reflection surface, and the parameters for the given reflector unit may be adjusted to optimize the angle space of light collection and the efficiency of light collection and reflection. For example, the reflection surface slope angle (a), the base horizontal width (Wh), the base vertical width (W_v), the vertical radius of curvature (R_v), and the horizontal radius of curvature (Rh) may be adjusted to optimize the performance of the reflector units 222, 222A. Further, a plurality of reflector units 222 may be used together to form a reflector. In some embodiments, the reflector units 222 may have identical geometric designs, but at least some of the reflector units 222 used to form a reflector may have different geometric designs in other embodiments. [0051] To make an RLCD operate efficiently, reflectors should be able to effectively collect ambient lights in a collection solid angle space which is determined by typical use cases. Collected ambient light may be reflected, and reflected light may be redirected to the viewer direction with a certain vertical and horizontal spread. Because of the reversibility of light propagation, the light collection angle space of a reflector will be the same as the angle space of the reflected light. Therefore, the design of a reflector should have a collection solid angle space that is equal to or larger than the greater of (1) the targeted angle spaces of light collection and (2) the angle space of reflected light. [0052] FIGS. 2C-2D illustrate further details regarding example reflection surfaces of the reflector units. Both of these figures illustrate cross-sectional views of example reflector units. In FIG. 2C, a curved reflection surface 212A is provided in the reflector unit 222A, with the reflection surface having smooth, continuous curvature therein. For the reflector unit 222B in FIG. 2D, curvature is provided in the reflection surface 212B along the horizontal direction in a plurality of flat surfaces. The cross-section illustrated in FIG. 2C extends along the same plane as the horizontal centerline 213B of FIG. 2B, and the cross-section illustrated in FIG. 2D may be provided at a similar location in another reflector unit. Furthermore, the smooth, continuous curvature or the plurality of flat surfaces may be used to form curvature along the vertical centerline 213 A or to form curvature along other locations in the reflector unit.

[0053] Additionally, the texture of the reflection surface may be altered to optimize a reflector for a given use case. For example, the reflection surface may be provided with a smooth finish to reduce the amount of scattering for reflected light being reflected off of the reflection surface. As another example, the reflection surface may be provided with a rough finish to increase the amount of scattering for reflected light being reflected off of the reflection surface. In some embodiments, the finish of the reflection surfaces within a reflector may be similar so that a similar amount of scattering occurs off of each reflection surface. However, in other embodiments, the finish of reflection surfaces may vary between different reflection units, and this may be beneficial where an increased amount of scattering is desired in certain reading directions.

[0054] An additional parameter that may be adjusted is the base shape for a reflector unit. FIG. 3 is a bottom view illustrating various example reflector units having different base shapes. For example, the reflector units may possess a triangle base shape 318A, a square base shape 318B, a rectangular base shape 318C, a pentagon base shape 318D, or a hexagon base shape 318E. The reflector units may be provided on a base surface in the display, and the base surface may define an available coverage area. Base shapes may be selected to maximize the area covered by reflector units or to maximize the angle space of light collection and the efficiency of light collection and reflection. In some embodiments, the parameters of the reflector units may be such that the entire available coverage area is covered. While five different base shapes are illustrated in FIG. 3, various other base shapes may be provided such as other polygonal shapes or other shapes having curved edges.

[0055] While individual reflector units are illustrated in earlier figures, multiple reflector units may be used together to form a reflector. FIGS. 4A-4D are schematic views illustrating a reflector having a plurality of reflector units that are tessellated about an available coverage area. In FIGS. 4A-4D, each reflector unit possesses a square base shape and all of the reflector units are geometrically identical to each other. In each of FIGS. 4A-4D, the orientation direction for each reflector unit is indicated by the arrows. Reflector units may be arranged to meet the needs of a particular use case and to form a uniform reflector with the high efficiencies of light collection and reflection.

[0056] Looking first at FIG. 4A, the reflector units 422A in the reflector 420A are provided with one orientation direction. This orientation direction is directed upwardly in FIG. 4A, but the orientation direction may be provided in other directions in other embodiments. Furthermore, a reflector block 424A may be formed. Given that each of the reflector units 422A possess the same orientation direction, the reflector block 424A may include just one reflector unit 422A. However, where reflector units are provided having different orientation directions, the reflector block may possess at least one of the different reflector units so that each of the different orientation directions are represented in the reflector block. In this way, the reflector block may be tessellated across the available coverage area so that light properties may be made relatively uniform throughout the display. The reflector block 424A may be sized such that the reflector block 424A is less than or equal to the size of a single pixel 1354 (see FIG. 13) in a display 1356 (see FIG. 13). In other embodiments, at least 1.5 reflector blocks may be provided in each pixel. Furthermore, at least two reflector blocks may be provided in each pixel. By providing reflector blocks that are smaller than the size of a single pixel, the reflector units and reflector blocks may be arranged relative to a pixel such that the amount of light provided at each pixel may be remain relatively uniform.

[0057] Where one orientation direction is used for the reflector units 422A, the amount of light collection and reflection efficiencies may be maximized. Thus, where one reading orientation is required for a given use case, a reflector similar to reflector 420A is ideal to maximize the amount of light collection and the reflection efficiency. However, it may be desirable to provide additional orientation directions where a display and the reflector therein may be used in different reading orientations.

[0058] Looking now at FIG. 4B, a schematic view is provided illustrating a reflector 420B comprising reflector units that are tessellated about an available coverage area, with two different orientation directions being provided. The first reflector unit 422A may possess a first orientation direction in an upward direction (a downward slope in the upward direction), and the second reflector unit 422B may possess a second orientation direction towards the right. Where this is the case, the reflector block 424B may include at least one first reflector unit 422A and at least one second reflector unit 422B, and the reflector block 424B may be tessellated across the available coverage area. Because reflector units having two different orientation directions are provided, the reflector 420B may be effectively used in two different reading orientations. Because the total reflection area is divided into two parts to address two different reading orientation cases, the light collection and reflection efficiencies for the reflector 420B of FIG. 4B are only about half of the light collection and reflection efficiencies for the reflector 420A of FIG. 4A. However, the benefit of the efficiencies received in two orientation directions may still outweigh the reduction in efficiencies in each orientation direction.

[0059] Turning now to FIG. 4C, a schematic view is provided illustrating a reflector 420C having a plurality of reflector units that are tessellated about an available coverage area. In the example of FIG. 4C, three orientation directions are provided in the reflector units. A first reflector unit 422A has a first orientation direction in an upward direction, a second reflector unit 422B has a second orientation direction towards the right, and a third reflector unit 422C has a third orientation direction in a downward direction. A reflector block 424C may include a first reflector unit 422A, a second reflector unit 422B, and a third reflector unit 422C so that the reflector block 424C is representative of the orientation directions used for the reflector units in the reflector 420C. By using reflector units having three different orientation directions, the reflector 420C may be used in three reading orientations. Because the total reflection area is divided into three parts which respectively address three reading orientation cases, the light collection and reflection efficiencies of the reflector 420C of FIG. 4C is about one third of the light collection and reflection efficiencies for the reflector 420A of FIG. 4A. However, the benefit of the efficiencies received in three orientation directions may still outweigh the reduction in efficiencies in each orientation direction.

[0060] Looking now at FIG. 4D, a schematic view is provided illustrating a reflector 420D having a plurality of reflector units that are tessellated about an available coverage area. In the illustrated embodiment of FIG. 4D, reflector units are illustrated having four different orientation directions. The first reflector unit 422A has a first orientation direction in an upward direction, the second reflector unit 422B has a second orientation direction towards the right, the third reflector unit 422C has a third orientation direction in a downward direction, and the fourth reflector unit 422D has a fourth orientation direction towards the left. A reflector block 424D may include a first reflector unit 422A, a second reflector unit 422B, a third reflector unit 422C, and a fourth reflector unit 422D so that the reflector block 424D is representative of the orientation directions used for the reflector units in a reflector. By using reflector units having four different orientation directions, the display and the reflector 420D therein may be used in four reading orientations. Because the total reflection area is divided into four parts which respectively address four reading orientation cases, the light collection and reflection efficiencies of the reflector 420D of FIG. 4D are about a quarter of the light collection and reflection efficiencies of the reflector 420A of FIG. 4A. However, the benefit of the efficiencies received in four orientation directions may still outweigh the reduction in efficiencies in each orientation direction.

[0061] In the illustrated embodiment of FIG. 4D, four orientation directions may be provided with each orientation direction separated by 90 degrees — the first orientation direction may be directed at an angle of 0 degrees (upwardly), the second orientation direction may be directed at an angle of 90 degrees (towards the right), the third orientation direction may be directed at an angle of 180 degrees (downwardly), and the fourth orientation direction may be directed at an angle of 270 degrees (towards the left). While FIG. 4D illustrates reflector units with orientation directions towards the left, right, up, and down, the reflector units may have other orientation directions (e.g. offset 30 degrees, 45 degrees, or 50 degrees from the first orientation direction of the reflector unit 422A).

[0062] Reflector units illustrated in FIGS. 4A-4D and other reflector blocks illustrated in FIGS. 5A-5C and FIGS. 6A-6C may possess either flat or curved reflection surfaces. Additionally or alternatively, the reflector units may possess different curvatures. In some embodiments, reflector units in different orientation directions may have different reflection surfaces such that the reflection surfaces are optimized for the anticipated light source for each direction of use. This may be beneficial to optimize a reflector for a particular use case. Similarly, in some embodiments, a pixel may encompass various ratios of different types of reflector units and/or reflector units in different orientation directions - enabling effective adjustment in the light efficiency for each pixel as desired for a use case. Notably, different relative sizing of reflector units may also be utilized.

[0063] While square base shapes are used for the reflector units of FIGS. 4A-4D, rectangular base shapes may be used in other embodiments while still covering the available coverage area. FIG. 5A-5C are schematic views illustrating reflectors having a plurality of reflector units that are tessellated about an available coverage area. In the embodiments of FIGS. 5A-5C, the reflector units each have rectangular base shapes.

[0064] Looking first at FIG. 5A, a reflector 520A having a plurality of reflector units is illustrated. A first reflector unit 522A is provided with a first orientation direction in the upward direction, a second reflector unit 522B is provided with a second orientation direction towards the right, a third reflector unit 522C is provided with a third orientation direction towards the left, and a fourth reflector unit 522D is provided with a fourth orientation direction in the downward direction. Each of the reflector units may possess identical geometric designs, and the different reflector units may simply be oriented differently. In the illustrated embodiment, a reflector block 524A includes a first reflector unit 522A, a second reflector unit 522B, a third reflector unit 522C, and a fourth reflector unit 522D. Thus, each of the orientation directions may be represented in a single reflector block 524A. Furthermore, the size of the reflector block 524A may be equal to or smaller than the size of a pixel 1354 (see FIG. 13), and this may be beneficial so that the pixels 1354 on a display 1356 (see FIG. 13) may maintain a more uniform appearance. The reflector 520A may be desirable where four reading orientations are necessary for a given use case.

[0065] In FIG. 5B, a reflector 520B is illustrated having reflector units that are oriented in two different orientation directions. Looking now at FIG. 5B, a reflector 520B having a plurality of reflector units is illustrated. A first reflector unit 522A’ is provided with a first orientation direction towards the right, and a second reflector unit 522B’ is provided with a second orientation direction in the upward direction. A single reflector block 524B may include at least one first reflector unit 522 A’ and at least one second reflector unit 522B’. In the illustrated embodiment, each reflector block 524B includes three first reflector units 522A’ and two second reflector units 522B’.

[0066] In the reflector 520B of FIG. 5B, the total area covered by the first reflector units 522A’ is different from the total area covered by the second reflector units 522B’. The first reflector units 522A’ may account for approximately sixty percent of the available coverage area, and the second reflector units may account for approximately forty percent of the available coverage area. However, these percentages may be varied in other embodiments. The total area devoted for each orientation direction may be adjusted to optimize the efficiency of light collection and reflection for each respective orientation direction. In some embodiments, while each of the first reflector units 522 A’ and the second reflector units 522B’ are geometrically identical, the geometry of the reflector units may differ to optimize the performance of the reflector units.

[0067] Turning now to FIG. 5C, a reflector 520C having a plurality of reflector units is illustrated. A first reflector unit 522A” is provided with a first orientation direction in the upward direction, a second reflector unit 522B” is provided with a second orientation direction towards the right, a third reflector unit 522C” is provided with a third orientation direction towards the left, and a fourth reflector unit 522D” is provided with a fourth orientation direction in the downward direction. While the second reflector unit 522B” and the third reflector unit 522C” are geometrically identical, the reflector units otherwise have different geometries. Within a single reflector block 524C, a first reflector unit 522A”, a second reflector unit 522B”, a third reflector unit 522C”, and a fourth reflector unit 522D” are provided so that each orientation direction is represented within the reflector block 524C. Due to the differing sizes of the reflector units, the area covered by each of the types of reflector units may differ. For example, the area of first reflector units 522A” may be less than the area of fourth reflector units 522D”.

[0068] By providing different base shapes, various tessellation patterns may be used for the reflector units. FIGS. 6A-6C show various alternative base shapes and tessellation patterns that may be deployed. Looking first at FIG. 6A, a schematic view is provided illustrating a reflector 620A having a plurality of reflector units that are tessellated about an available coverage area. In the illustrated embodiment, each of the reflector units share identical geometries, and the different reflector units vary in their orientation. Each of the reflector units possess a hexagonal base shape. Further, the first reflector unit 622A possesses a first orientation direction in the upward direction, the second reflector unit 622B possesses a second orientation direction towards the right, and the third reflector unit 622C possesses a third orientation direction in the downward direction. A reflector block 624 may include at least one of each of these different reflector units. While the reflector block 624 includes one of each of the first reflector unit 622A, the second reflector unit 622B, and the third reflector unit 622C, the reflector block 624 may be adjusted to include additional reflector units (e.g. an additional second reflector unit 622B) in some embodiments.

[0069] FIGS. 6B-6C are schematic views illustrating a plurality of reflector units that are tessellated about an available coverage area. In the examples illustrated in FIGS. 6B-6C, the base shapes of the reflector units differ. In FIG. 6B, the reflector 620B has a plurality of reflector units, including a first reflector unit 622A’ having a triangular base shape and a second reflector unit 622B’ having a hexagonal base shape. Further, in FIG. 6C, the reflector 620C includes first reflector units 622A” having an octagonal base shape and second reflector units 622B” having a square base shape. FIGS. 6B-6C are examples of some of the tessellation patterns that may be formed using the reflector units, and a wide variety of other tessellation patterns may be used. The ability to use reflector units having different shapes allows one to maximize the area covered by the reflector units (and/or customize the desired light reflection efficiency as noted herein). Notably, the use of different shapes may be particularly beneficial where the available coverage area is not simply a rectangular shape. For example, where a display has rounded edges at its comers, it may be beneficial to use a base shape other than a rectangular or square base shape.

[0070] Perspective views of reflector units having a rectangular base shape are illustrated in FIGS. 7A-7B. Looking first at FIG. 7A, a perspective view is provided illustrating a reflector 720 with reflector units 722 provided therein. The reflector units 722 have a rectangular base shape and a curved reflection surface. Each of the reflector units 722 may possess a unit orientation that is directed upwardly and towards the left from the perspective illustrated in FIG. 7A. Because each of the reflector units possess the same unit orientation, a reflector block 724 may include one reflector unit 722, and other reflector units in the reflector 720 may be geometrically identical to the reflector unit 722. Furthermore, each reflector unit 722 may possess a rectangular base having a base horizontal width (Wh) and a base vertical width (W_v). These values may be similar to those described elsewhere herein.

[0071] The reflection surface 212A (see FIG. 2B) of the reflector units 722 may be sloped relative to the base surface 214 (see FIG. 2B) of the reflector units 722 to control the direction of the reflected light. Further, the reflection surface may be curved to control collection light angle ranges (or reflected light angle ranges) in vertical and/or horizontal directions. As shown in FIG. 7A, the reflector units 722 are tiled together to form a reflector 720.

[0072] Further details regarding the reflector units are illustrated in FIG. 7B, which provides an enhanced perspective view illustrating a reflector unit 722. As illustrated, the reflector unit 722 may possess a curved reflection surface having a three-dimensional curvature. The three-dimensional curvature may possess curvature at a vertical curvature centerline 726A and a horizontal curvature centerline 726B. Various types of curvature may be provided at these centerlines, including but not limited to, for example, radial curvatures, parabolic curvatures, sine curvatures, asymmetrical curvatures, a polygonal curvature (see FIG. 2D), etc. However, the curvature at the vertical curvature centerline 726A and the horizontal curvature centerline 726B are radial curvatures in the illustrated embodiment, with a vertical radius of curvature (R_v) defined at the vertical curvature centerline 726A and a horizontal radius of curvature (Rh) being defined at the horizontal curvature centerline 726B.

[0073] The reflector units 722 and other reflector units describe herein may be made by micro-imprinting technology. A master stamp may be generated with the designed features. Furthermore, a lacquer may be coated on the glass substrates and then imprinted with the stamps and cured. The feature surfaces may be metallized or coated with high reflection materials to achieve targeted reflectivity. These techniques may assist in manufacturing the reflector units 722 and reflectors described herein in a cost-efficient manner. Furthermore, using reflectors having reflector units with identical geometries and/or more simplified geometries may also improve the cost-efficiency of manufacturing.

[0074] Further details regarding the reflector units is illustrated in FIG. 8. FIG. 8 is a schematic cross-sectional view illustrating two reflector units 822 having curved reflection surfaces 812A. The cross-sectional view of FIG. 8 illustrates an example cross-sectional view of the reflector units 822 provided along the y-z plane in FIG. 7A. The reflector units 822 may possess a unit orientation that is directed towards the left from the perspective illustrated in FIG. 8, with the curved reflection surfaces sloped downwardly towards the left. The reflector units 822 are provided in a plenary layer 828 having a plenary later thickness (t_p). The plenary layer 828 may have transparent material, and the plenary later thickness (t_p) may be greater than the height of the reflection units 822. Further, the reflector units 822 may be provided on a base surface 830, and the reflector units 822 may each possess a base vertical width (W_v).

[0075] FIG. 9 is a graph illustrating example radiance in angle space values for a reflector unit. On the y-axis, the radiance in angle space is provided, with the units for radiance in angular space being watts/(sr*cm²). On the x-axis, the relevant x-coordinate angle is provided in degrees. As illustrated, the radiance is highest at zero degrees, and the radiance values may be above zero within the range of -4.0 degrees to 4.0 degrees. Outside of this range, the radiance for a given reflector unit will be zero or a very small amount close to zero. The incident ambient light may be a collimated beam with a divergent angle of ~2 degrees, and the vertical center incident angle (0_C) and horizontal center incident angles (co_c) of the ambient light may be 30 degrees and 0 degrees respectively.

[0076] FIGS. 10A-10C are graphs illustrating example angular distributions for reflected light for different reflector units. In FIG. 10A, a graph is illustrated for a reflector unit having a unit width of 14.4 micrometers. In FIG. 10B, a graph is illustrated for a reflector unit having a unit width of 21.6 micrometers. Additionally, in FIG. 10C, a graph is illustrated for a reflector unit having a unit width of 28.8 micrometers. For the reflector unit of FIG. 10A, the radiance in angle space is approximately 0.0005 at all positions within the angular distributions. For the reflector unit of FIG. 10B, the radiance in angle space is approximately 0.0003 at all positions within the angular distributions. For the reflector unit of FIG. 10C, the radiance in angle space is approximately 0.0002 at all positions within the angular distributions. For each of the graphs, radiance in angle space remains relatively uniform within the angular distributions.

[0077] FIG. 11A-11B are graphs illustrating the normalized reflective light power and angular distribution of reflective light obtained for various reflector units having different structure widths but the same curvature in the vertical and horizontal directions. Looking first at FIG. 11 A, a graph is shown with the x-axis reflecting the angle in degrees and with the y- axis reflecting the normalized reflected light power. The normalized reflected light power is equal to the power of reflected light at a given angle divided by the power of incident light at the angle space peak (of FIG. 9) times 100. The graph provides the cross-section angular distribution along the vertical curvature centerline 726A. A first plotline 1136, a second plotline 1134, and a third plotline 1132 are illustrated. The first plotline 1136 is for a rectangular reflector unit having a unit width of 14.4 micrometers, the second plotline 1134 is for a rectangular reflector unit having a unit width of 21.6 micrometers, and the third plotline 1132 is for a rectangular reflector unit having a unit width of 28.8 micrometers. As illustrated, the first plotline 1136 for the 14.4-micrometer reflector unit may have normalized reflected light power values of approximately 0.36 between -9.9 and 9.9 degrees, the second plotline 1134 for the 21.6-micrometer reflector unit may have normalized reflected light power values of approximately 0.24 between -9.9 and 9.9 degrees, and the third plotline 1132 for the 28.8- micrometer reflector unit may have normalized reflected light power values of approximately 0.18 between -9.9 and 9.9 degrees. Normalized reflected light power values may be generally uniform within the relevant angles of -9.9 and 9.9 degrees for each plotline, and further details regarding the uniformity in view angles ranges are provided in the table below.

[0078] Looking now at FIG. 1 IB, a graph is shown with the x-axis reflecting the angle in degrees and with the y-axis reflecting the normalized reflected light power. The graph provides the cross-section angular distribution along the horizontal curvature centerline 726B. A first plotline 1142, a second plotline 1140, and a third plotline 1138 are illustrated. The first plotline 1142 is for a rectangular reflector unit having a unit width of 14.4 micrometers, the second plotline 1140 is for a rectangular reflector unit having a unit width of 21.6 micrometers, and the third plotline 1138 is for a rectangular reflector unit having a unit width of 28.8 micrometers. As illustrated, the first plotline 1142 for the 14.4-micrometer reflector unit may have normalized reflected light power values of approximately 0.36 between -11.9 and 11.9 degrees, the second plotline 1140 for the 21.6-micrometer reflector unit may have normalized reflected light power values of approximately 0.24 between -17.9 and 17.9 degrees, and the third plotline 1138 for the 28.8-micrometer reflector unit may have normalized reflected light power values of approximately 0.18 between -24.9 and 24.9 degrees. Normalized reflected light power values may be generally uniform within the relevant angles for each plotline, and further details regarding the uniformity in view angles ranges are provided in the table below. TABLE 1

[0079] Table 1 above provides the performance of different reflectors. For the first case, a reflector using rectangular reflector units having a unit width of 14.4 micrometers is provided. Such a reflector may have view angles ranging from -9.9 degrees to 9.9 degrees in the vertical direction. These values for the vertical direction may correspond to the first plotline 1136 of FIG. 11 A. Further, the uniformity of light reflection may be 94.1 percent in the vertical direction. In the horizontal direction, the reflector in the first case may have view angles ranging from -11.9 degrees to 11.9 degrees. Further, the uniformity of light reflection may be 98.8% in the horizontal direction. These values for the horizontal direction may correspond to the first plotline 1142 of FIG. 1 IB.

[0080] For the second case, a reflector using rectangular reflector units having a horizontal unit width of 21.6 micrometers is provided. Such a reflector may have view angles ranging from -9.9 degrees to 9.9 degrees in the vertical direction. Further, the uniformity of light reflection may be 94.5 percent in the vertical direction. These values for the vertical direction may correspond to the second plotline 1134 of FIG. 11 A. In the horizontal direction, the reflector in the first case may have view angles ranging from -17.9 degrees to 17.9 degrees. Further, the uniformity of light reflection may be 97.1% in the horizontal direction. These values for the horizontal direction may correspond to the second plotline 1140 of FIG. 1 IB.

[0081] For the third case, a reflector using rectangular reflector units having a horizontal unit width of 28.8 micrometers is provided. Such a reflector may have view angles ranging from -9.9 degrees to 9.9 degrees in the vertical direction. Further, the uniformity of light reflection may be 91.4 percent in the vertical direction. These values for the vertical direction may correspond to the third plotline 1132 of FIG. 11 A. In the horizontal direction, the reflector in the first case may have view angles ranging from -24.9 degrees to 24.9 degrees. Further, the uniformity of light reflection may be 96.1% in the horizontal direction. These values for the horizontal direction may correspond to the third plotline 1138 of FIG. 1 IB. [0082] As shown by Table 1 above, the reflector design enables reflected light to be uniformly distributed in a target angle space. In each of the cases illustrated in the table, the uniformity of light reflection is greater than 91% in the vertical direction. Furthermore, the uniformity of light reflection is greater than 96% in the horizontal direction in each of the cases illustrated in the table. Furthermore, the range of view angles in the horizontal direction may be changed by altering the horizontal width of reflector units, and this may be done without changing the range of view angles in the vertical direction.

[0083] Where RLCDs are used with vertical light collection angles of thirty degrees, the designs may enable an RLCD with a vertical light collection angle of 30 degrees ± 10 degrees. Further, the designs may enable horizontal light collection angles (o) of 0 degrees ± 12 degrees, 0 degrees ± 18 degrees, or 0 degrees ± 25 degrees depending on the horizontal width (Wh) of the reflector units. These values may be obtained where the RLCD is in the y-z plane of FIG. 1A.

[0084] Uniformity values provided in Table 1 above may be calculated by dividing the minimum normalized reflected light power within the view angles by the maximum normalized reflected light power within the view angles, and the uniformity values are provided as percentages. For the modelling used in Table 1 above and for the graphs illustrated in FIGS. 9-1 IB, a reflector was used having a reflector units sharing the same unit orientations. In the model, the vertical curvature (R_v) of the reflector units was 198.5 micrometers, the horizontal curvature (Rh) of the reflector units was 99.2 micrometers, the vertical width (W_v) of reflector units was 24.3 micrometers, and the structure height (H) of the reflector units was 4 micrometers. The horizontal width (Wh) of the reflector units was 14.4 micrometers, 21.6 micrometers, or 28.8 micrometers, depending on the particular case. Furthermore, the reflection surface slope angle (a) was 9.5 degrees, and the back wall angle (P) was 85 degrees. The reflection surface possessed a reflectivity of 95 percent. Further, the plenary layer thickness (t_p) of the plenary layer 828 (see FIG. 8) was 4.2 micrometers. The plenary layer refractive index was 1.55 at 550 nanometers. Further, the vertical center incident angle (0_C) was 30 degrees and the horizontal center incident angle (co_c) was 0 degrees. Further, the base plane of the reflector is in the y-z plane, and the viewer is presumed to be in the normal to the base plane along the x axis. These values are merely exemplary values that may be used in the design of a reflector and/or various reflector units, and these values may be adjusted to optimize the efficiency of a given reflector and/or reflector unit while meeting the requirements of a particular use case. [0085] Additionally, FIG. 12A is a schematic view illustrating an example light collection angle off of a display. A reflected light collection cone 1246 may be formed from light reflecting off of the display. As illustrated, the reflected light collection cone 1246 may have a light collection cone angle (y). Reflected light may be redirected to the viewer direction, which is typically in the direction of the display normal. For example, in FIG. 12A, reflected light is redirected towards a viewer towards the right. The reflected light may be redirected with a certain vertical and horizontal spread as indicated by the reflected light collection cone 1246.

[0086] Turning now to FIG. 12B, a graph is provided illustrating the reflection efficiency on the y-axis and the light collection cone angle on the x-axis. The light collection cone angle may be provided in degrees. The graph includes a first plotline 1252, a second plotline 1250, and a third plotline 1248. The first plotline 1252 shows results for a reflector unit having a horizontal width (Wh) of 14.4 micrometers. The second plotline 1250 shows results for a reflector unit having a horizontal width (Wh) of 21.6 micrometers. The third plotline 1248 shows results for a reflector unit having a horizontal width (Wh) of 28.8 micrometers. As illustrated, the first plotline 1252 has the highest reflection efficiency at a given light collection cone angle, and the third plotline 1248 has the lowest reflection efficiency at a given light collection cone angle. Thus, as the horizontal width (Wh) of a reflector unit is increased, this will generally result in a decrease in the reflection efficiency.

[0087] FIG. 13 is a front view illustrating an example display 1356 having a plurality of pixels 1354. A reflector block may cover a reflector block coverage area on a base surface, and the reflector block coverage area may be equal to or less than the area of a single pixel 1354 for the reflective liquid crystal display. By doing so, configurations of reflector units and reflector blocks that enable uniformity to be maintained from pixel to pixel. Further, where a reflector includes reflector units having different orientation directions, a reflector block may include reflector units having each of the different orientation directions that are used in the reflector. In other words, each of the different orientation directions may be represented in a single reflector block. In this way, the reflector blocks and the pixels 1354 may remain uniform across the display 1356.

CONCLUSION

[0088] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments of the invention are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the invention. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the invention. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated within the scope of the invention. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

THAT WHICH IS CLAIMED:

1. A reflective liquid crystal display comprising: a base surface; one or more first reflector units, wherein each first reflector unit of the one or more first reflector units defines a first reflection surface, wherein each first reflector unit of the one or more first reflector units is positioned on the base surface so that each first reflection surface of the one or more first reflector units defines a downward slope in a first orientation direction; and one or more second reflector units, wherein each second reflector unit of the one or more second reflector units defines a second reflection surface, wherein each second reflector unit of the one or more second reflector units is positioned on the base surface so that each second reflection surface of the one or more second reflector units defines a downward slope in a second orientation direction, wherein the first orientation direction is perpendicular to the second orientation direction.

2. The reflective liquid crystal display of Claim 1, wherein the one or more first reflector units cover a first coverage area, wherein the one or more second reflector units cover a second coverage area, and wherein the first coverage area is greater than the second coverage area.

3. The reflective liquid crystal display of Claim 1, wherein each first reflector unit of the one or more first reflector units and each second reflector unit of the one or more second reflector units are geometrically identical, and wherein each first reflector unit of the one or more first reflector units is positioned on the base surface in a different orientation than each second reflector unit of the one or more second reflector units.

4. The reflective liquid crystal display of Claim 1, wherein the base surface defines a coverage area, and wherein the one or more first reflector units and the one or more second reflector units cover the coverage area entirely.

5. The reflective liquid crystal display of Claim 4, wherein each first reflector unit of the one or more first reflector units and each second reflector unit of the one or more second reflector units defines a base having a base shape, wherein a first group of reflector units comprises at least one of the one or more first reflector units or the one or more second reflector units, wherein each reflector unit of the first group of reflector units defines a first base shape, wherein a second group of reflector units comprises at least one of the one or more first reflector units or the one or more second reflector units, wherein each reflector unit of the second group of reflector units defines a second base shape, and wherein the second base shape is different than the first base shape.

6. The reflective liquid crystal display of Claim 5, wherein the first group of reflector units includes a first reflector unit of the one or more first reflector units and a second reflector unit of the one or more second reflector units.

7. The reflective liquid crystal display of Claim 5, wherein the base shape is selected from the group consisting of a triangle, a rectangle, a square, a pentagon, a hexagon, and another polygonal shape.

8. The reflective liquid crystal display of Claim 1, wherein a reflector block includes a first reflector unit of the one or more first reflector units and a second reflector unit of the one or more second reflector units.

9. The reflective liquid crystal display of Claim 8, wherein the reflector block defines a reflector block base shape, wherein the base surface defines a coverage area, and wherein the reflector block base shape is tessellated to cover all of the coverage area.

10. The reflective liquid crystal display of Claim 8, wherein the reflector block covers a reflector block coverage area, and wherein the reflector block coverage area is less than an area of a pixel.

11. The reflective liquid crystal display of Claim 1, wherein each first reflection surface of the one or more first reflector units and each second reflection surface of the one or more second reflector units defines a curvature.

12. The reflective liquid crystal display of Claim 11, wherein the curvature is threedimensional.

13. The reflective liquid crystal display of Claim 11, the curvature is radially curved, parabolically curved, asymmetrically curved, polygonally curved, or includes a sine curvature.

14. The reflective liquid crystal display of Claim 1, further comprising: one or more third reflector units, wherein each third reflector unit of the one or more third reflector units defines a third reflection surface, wherein each third reflector unit of the one or more third reflector units is positioned on the base surface so that each third reflection surface of the one or more third reflector units defines a downward slope in a third orientation direction, wherein the third orientation direction is different from the first orientation direction and the second orientation direction.

15. The reflective liquid crystal display of Claim 14, further comprising: one or more fourth reflector units, wherein each fourth reflector unit of the one or more fourth reflector units defines a fourth reflection surface, wherein each fourth reflector unit of the one or more fourth reflector units is positioned on the base surface so that each fourth reflection surface of the one or more fourth reflector units defines a downward slope in a fourth orientation direction, wherein the fourth orientation direction is different from the first orientation direction, the second orientation direction, and the third orientation direction.

16. The reflective liquid crystal display of Claim 1, wherein the first reflection surface or the second reflection surface possesses a smooth finish.

17. The reflective liquid crystal display of Claim 1, wherein the first reflection surface or the second reflection surface possesses a roughened finish.

18. A reflective liquid crystal display comprising: a base surface; one or more first reflector units, wherein each first reflector unit of the one or more first reflector units defines a first reflection surface and a first base, wherein each first reflector unit of the one or more first reflector units is positioned on the base surface so that each first reflection surface of the one or more first reflector units defines a downward slope in a first orientation direction, wherein each first base of the one or more first reflector units has a first base shape; and one or more second reflector units, wherein each second reflector unit of the one or more second reflector units defines a second reflection surface and a second base, wherein each second reflector unit of the one or more second reflector units is positioned on the base surface so that each second reflection surface of the one or more second reflector units defines a downward slope in a second orientation direction, wherein each second base of the one or more second reflector units has a second base shape, and wherein the first base shape is different from the second base shape.

19. A reflective liquid crystal display comprising: a base surface; one or more first reflector units, wherein each first reflector unit of the one or more first reflector units defines a first reflection surface, wherein each first reflector unit of the one or more first reflector units is positioned on the base surface so that each first reflection surface of the one or more first reflector units defines a downward slope in a first orientation direction, wherein each first reflection surface of the one or more first reflector units is curved and defines a first curvature; and one or more second reflector units, wherein each second reflector unit of the one or more second reflector units defines a second reflection surface, wherein each second reflector unit of the one or more second reflector units is positioned on the base surface so that each second reflection surface of the one or more second reflector units defines a downward slope in a second orientation direction, wherein each second reflection surface of the one or more second reflector units is curved and defines a second curvature, wherein the first orientation direction is different from the second orientation direction, and wherein the first curvature is different from the second curvature.

20. A reflective liquid crystal display comprising: a base surface; and reflector units, wherein each reflector unit of the reflector units defines a reflection surface, wherein the reflector units are positioned on the base surface so that each reflection surface of the reflector units defines a downward slope in an orientation direction, wherein the base surface defines a coverage area, and wherein the reflector units cover the coverage area entirely.

21. The reflective liquid crystal display of Claim 20, further comprising reflector blocks, wherein the reflector blocks include multiple reflector units having different orientation directions, and wherein the reflector blocks are tessellated to cover the coverage area entirely.

22. A reflective liquid crystal display comprising: a base surface; a plurality of pixels; a plurality of reflector blocks, wherein each reflector block of the plurality of reflector blocks includes: one or more first reflector units, wherein each first reflector unit of the one or more first reflector units defines a first reflection surface, wherein each first reflector unit of the one or more first reflector units is positioned on the base surface so that each first reflection surface of the one or more first reflector units defines a downward slope in a first orientation direction; and one or more second reflector units, wherein each second reflector unit of the one or more second reflector units defines a second reflection surface, wherein each second reflector unit of the one or more second reflector units is positioned on the base surface so that each second reflection surface of the one or more second reflector units defines a downward slope in a second orientation direction, and wherein each pixel of the plurality of pixels includes at least one reflector block.

23. The reflective liquid crystal display of Claim 22, wherein at least 1.5 reflector blocks are provided in each pixel of the plurality of pixels.

24. The reflective liquid crystal display of Claim 22, wherein at least 2 reflector blocks are provided in each pixel of the plurality of pixels.

25. The reflective liquid crystal display of Claim 22, wherein each reflector block of the plurality of reflector blocks also includes: one or more third reflector units, wherein each third reflector unit of the one or more third reflector units defines a third reflection surface, wherein each third reflector unit of the one or more third reflector units is positioned on the base surface so that each third reflection surface of the one or more third reflector units defines a downward slope in a third orientation direction; one or more fourth reflector units, wherein each fourth reflector unit of the one or more fourth reflector units defines a fourth reflection surface, wherein each fourth reflector unit of the one or more fourth reflector units is positioned on the base surface so that each fourth reflection surface of the one or more fourth reflector units defines a downward slope in a fourth orientation direction, wherein the first orientation direction, the second orientation direction, the third orientation direction, and the fourth orientation direction are each different.