Reflective display including a reflector

Abstract

A reflective display includes a plurality of pixels, wherein each pixel includes an active area. The reflective display includes an array of reflectors within an active area of each pixel. Each reflector in the array of reflectors is directly adjacent to another reflector in the array of reflectors. Each of the reflectors in the array of reflectors is fully reflective, and each of the reflectors in the array of reflectors includes a curved first surface.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority under 35 USC § 119 to U.S. Provisional Application Serial No. 63 / 367,001, filed on June 24, 2022, the contents of which are the basis of this application and are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to displays. More particularly, the present disclosure relates to reflective displays including a reflector. Background Art

[0004] Reflective displays, such as reflective liquid crystal displays (RLCD), do not include a backlight unit. Instead, reflective displays can be viewed by reflecting ambient light from external sources (such as the sun, lamps, ambient light, etc.). Reflective displays are of interest due to their low energy consumption. Reflective displays have many applications, such as mobile phones, e-readers, and public signage. Since there is no backlight unit, the management of incident light determines the brightness of the image displayed on the reflective display. Summary of the invention

[0005] Some embodiments of the present disclosure relate to a reflective display. The reflective display includes a plurality of pixels, wherein each pixel includes an active area. The reflective display includes a reflector array within the active area of ​​each pixel. Each reflector in the reflector array is directly adjacent to another reflector in the reflector array. Each reflector in the reflector array is fully reflective, and each reflector in the reflector array includes a curved first surface.

[0006] Still other embodiments of the present disclosure relate to a reflective display. The reflective display includes a plurality of pixels, wherein each pixel includes an active area. The reflective display includes an array of reflectors within the active area of ​​each pixel. Each reflector in the reflector array is directly adjacent to another reflector in the reflector array. Each reflector in the reflector array is fully reflective, and each reflector in the reflector array includes a first surface having a first slope and a second surface having a second slope different from the first slope.

[0007] Still other embodiments of the present disclosure relate to a reflective display. The reflective display includes a plurality of pixels, wherein each pixel includes an active area. The reflective display includes a reflector array within the active area of ​​each pixel. Each reflector in the reflector array is directly adjacent to another reflector in the reflector array, and each reflector in the reflector array includes an inverted pyramid or cone.

[0008] The reflective display disclosed herein can be manufactured by forming each reflector array on a substrate (e.g., glass) using precision micro-replication by heat or monomer cross-linking processes. Each reflector array has a unit geometry that is optimized to redirect incident light to a viewer depending on the application. The horizontal diffusion of the redirected light can be adjusted by changing the unit geometry or providing a reflector with a rough reflective surface. Depending on the application, the diffuseness of the redirected light can be controlled based on the orientation distribution of the unit geometry. In addition, potential undesirable Moiré fringes can be mitigated by the orientation distribution of the unit geometry. The controlled viewing angle of the reflective display also provides a privacy feature for larger viewing angles, that is, the display is only visible within a given viewing angle.

[0009] Additional features and advantages will be set forth in the detailed description that follows, and in part will be apparent to those skilled in the art from that description or learned by practicing the embodiments as described herein, including the following detailed description, claims, and drawings.

[0010] It should be understood that the foregoing general description and the following detailed description are only exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate one or more embodiments and together with the description explain the principles and operation of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram illustrating an exemplary reflective display, a light source, and a viewer;

[0012] Figure 2A and Figure 2B is a schematic diagram illustrating an exemplary use case of a reflective display;

[0013] FIG. 3A to FIG. 3F is a schematic diagram illustrating exemplary light illumination of a reflective display;

[0014] Figure 4 is an angular graph illustrating the directional distribution of reflection;

[0015] Figure 5 illustrates different views of an exemplary reflector;

[0016] Fig. 6A is a top view illustrating an exemplary reflective display;

[0017] FIG. 6B to FIG. 6D is a cross-sectional view of an exemplary reflective display;

[0018] Fig. 7A and Figure 7B are top and side views of a pixel of an exemplary reflective display;

[0019] Figure 7C is an example Fig. 7A and Figure 7B An angular graph of the directional distribution of reflection of a reflective display;

[0020] Fig. 8A is a top view of a pixel of another exemplary reflective display;

[0021] Figure 8B Example Fig. 8A An exemplary reflector design for a reflective display of;

[0022] Figure 8C is an example Figure 8B An angular graph of the directional distribution of reflection for a reflector design;

[0023] Fig. 9A is a top view of a pixel of another exemplary reflective display;

[0024] Fig. 9B Illustrated Fig. 9A An exemplary reflector design for a reflective display of;

[0025] Fig. 9C is an example Fig. 9B An angular graph of the directional distribution of reflection for a reflector design;

[0026] Fig.9D Illustrated Fig. 9A Another exemplary reflector design for a reflective display of;

[0027] Fig.9E is an example Fig.9D An angular graph of the directional distribution of reflection for a reflector design;

[0028] Fig. 10A is a top view of a pixel of another exemplary reflective display;

[0029] Fig. 10B Example Fig. 10A An exemplary reflector design for a reflective display of;

[0030] Fig. 10C is an example Fig. 10B An angular graph of the directional distribution of reflection for a reflector design;

[0031] Fig.11A is a top view of a pixel of another exemplary reflective display;

[0032] Fig. 11B and Fig. 11C is an example Fig.11A Angular graph of an exemplary orientation distribution of a reflective display;

[0033] Fig. 12A and Fig. 12B are cross-sectional views of other exemplary reflectors;

[0034] Fig.13A and Fig. 13B An exemplary inverted pyramid reflector is illustrated;

[0035] Fig. 13C and Fig.13D is an example Fig.13A and Fig. 13B Graph of exemplary angular distribution of the outcoupled light intensity of an inverted pyramid reflector.

[0036] Fig.14A and Fig. 14B An exemplary inverted conical reflector is illustrated; and

[0037] Fig. 14C is an example Fig.14A and Fig. 14B Graph of exemplary angular distribution of the outcoupled light intensity of an inverted conical reflector.

[0038] Fig.15 is a graph illustrating an exemplary angular distribution of reflected light for a reflector having a curved reflective surface.

[0039] Fig.16 It is shown Fig.15 Angular distribution of .

[0040] Fig.17 is a graph comparing exemplary angular distributions of reflected light for reflectors having curved reflective surfaces with smooth and rough surfaces.

[0041] Fig.18 is a graph illustrating an exemplary angular distribution of reflected light for a reflector having a curved and roughened reflective surface.

[0042] Fig.19 It is shown Fig.18 Graph of the angular distribution of . DETAILED DESCRIPTION

[0043] Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same component symbols will be used throughout the drawings to refer to the same or similar parts. However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0044] Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such ranges are expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations by using the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each range are significant both relative to the other endpoint and independently of the other endpoint.

[0045] Directional terms used herein—eg, up, down, right, left, front, back, top, bottom, vertical, horizontal—are made with reference only to the drawings in which they are drawn and are not intended to imply an absolute orientation.

[0046] Unless otherwise expressly stated, any method described herein is in no way intended to be interpreted as requiring that its steps be performed in a particular order, nor is it intended to require a particular orientation for any apparatus. Thus, if a method claim does not actually recite the order in which its steps are to be followed, or any apparatus claim does not actually recite the order or orientation of individual components, or if there is no other specific statement in the claims or specification that the steps are limited to a particular order, or if there is no specific order or orientation of components of the apparatus, then no order or orientation is intended to be inferred in any respect. This applies to any possible non-explicit basis for interpretation, including: logical issues regarding arrangement of steps, operational flow, order of components, or orientation of components; plain meaning from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0047] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components unless the context clearly dictates otherwise.

[0048] The redirection of reflected light in a reflective display can be characterized by two factors, including the brightness in the direction of the viewer and the horizontal diffusion. The horizontal diffusion refers to the diffusion of light in a plane perpendicular to the plane of incidence. The light reflection in a reflective display can be controlled by a bump-shaped reflective texture made using photolithography inside the liquid crystal display (LCD) cell. This bump-shaped reflective texture can be called an isotropic in-cell reflector (IICR). The light reflection in a reflective display can also be controlled by a refractive index / birefringence gradient film to guide the light. This refractive index / birefringence gradient film can be called a light control film (LCF). However, IICR and LCF have several disadvantages that result in unsatisfactory performance in applications. The photolithography and subsequent etching used for IICR only form symmetrical reflective textures (e.g., hemispherical). Therefore, in IICR, the light reflected to the viewer has a restricted direction. In addition, the curvature of the reflective surface cannot be controlled. LCF can achieve the desired retroreflective properties, however, LCF may have parallax issues because the film is laminated on the outside of the reflective display front glass and polarizer. In addition, LCF introduces birefringence and reduces the contrast of the reflective display. Therefore, a reflective display including a reflector that does not have the disadvantages of IICR and LCF is disclosed herein.

[0049] Now refer to Figure 1 , a schematic diagram illustrating an exemplary reflective display 102, a light source 104, and a viewer 106 is depicted. Figure 1 An ideal operating mode of a reflective display 102 is depicted. Light from a light source 104 is incident on the reflective display 102, as shown at 108. If no redirection device is present in the reflective display 102, the image light is reflected in a specular direction, as shown at 110, and no image light reaches the viewer's eye 106. If a redirection device is present in the reflective display 102, the image light is reflected to the viewer's eye 106, as shown at 112. Therefore, the reflective display 102 should include a reflection control device to redirect the light to the viewer. The characteristics of such a reflection control device depend on the condition of the light source 104, the use of the reflective display 102, and the desired diffusion of the reflected light.

[0050] Figure 2A and Figure 2B is a schematic diagram illustrating an exemplary use case of a reflective display. Figure 2AThe reflective display 122 and the light source 104 are included. In this example, the reflective display 122 is fixed so that the reflective display 122 cannot rotate. The reflective display 122 can be, for example, a public sign. In this case, the direction of the incident light from the light source 104 as shown at 108 is fixed relative to the orientation of the reflective display 122. Figure 2B A reflective display 132 and a light source 104 are included in a landscape orientation and a portrait orientation. In this example, the reflective display 132 is not fixed, so that the reflective display 132 can be rotated. The reflective display 132 can be, for example, a portable device. In this case, the direction of the incident light from the light source 104 as shown in 108 is not fixed relative to the orientation of the reflective display 132. Each reflective display 122 and 132 includes a different symmetry in terms of reflector geometry. In addition, each reflective display 122 and 132 controls the diffusion of the reflection to optimize the use of the incident light.

[0051] FIG. 3A to FIG. 3F Different light illuminations of a reflective display 142 are illustrated. An emitting surface 140 directs ambient light to the reflective display 142, which may have various angular orientations. A viewer of the reflective display 142 is indicated by 106. The emitting surface 140 may be a ceiling, a wall, a window, etc., with light 144 coming from the emitting surface. Figure 3A 140 is an example of how ambient light may illuminate reflective display 142 when direct light, such as direct sunlight, is not considered. In such cases, the diffuse profile of the ambient light, the directionality of the ambient light, and the orientation of reflective display 142 relative to emitting surface 140 are parameters that affect the light reflected from the reflective display. Figure 3A In FIG. 1 , the reflective display 142 is oriented at an angle of approximately 60 degrees relative to the emitting surface 140. Figure 3B In FIG. 1 , the reflective display 142 is oriented at an angle of approximately 90 degrees relative to the emitting surface 140. Figure 3C In FIG. 1 , the reflective display 142 is oriented at an angle of approximately 75 degrees relative to the emitting surface 140. Figure 3D In FIG. 1 , the reflective display 142 is oriented at an angle of approximately 60 degrees relative to the emitting surface 140. Figure 3E In FIG. 1 , the reflective display 142 is oriented at an angle of approximately 45 degrees relative to the emitting surface 140. Figure 3F , the reflective display 142 is oriented at an angle of approximately 30 degrees relative to the emitting surface 140. In other examples, other orientations of the reflective display 142 relative to the emitting surface 140 are possible.

[0052] Figure 42 is an angular graph 200 that illustrates the directional distribution of reflection in degrees. Vertical line 202 indicates the azimuth or plane of incidence, while horizontal line 204 is the reading direction (perpendicular to 202). Point 206 corresponds to the direction of the incident light (about 30 degrees from the display normal), while point 208 corresponds to the specular reflection. The IICR reflects most of the light in directions below the horizontal direction and is not used for viewing. The LCF redirects more light in useful directions (not shown), but the use of an LCF generally results in reduced contrast due to birefringence. The reflective display disclosed herein solves the problems of the IICR and LCF described above and provides improved controllability of the distribution of reflected light.

[0053] Figure 5 Different views of an exemplary reflector 300 are illustrated. The reflector 300 has an asymmetric geometry, including a reflective first surface 302, a planar second surface 304 extending to the first surface 302, and a third surface 306 extending between the first surface 302 and the second surface 304. The reflector 300 is defined by a total length L, a width W, a reflector portion length D, a first angle θ1, a second angle θ2, and a first surface 302 curvature R. The first surface 302 curvature can be convex or concave. Adjustment of the parameters L, D, θ1, θ2, W, and R controls the angular range of reflection for a given ambient light input. The reflector 300 (e.g., the first surface 302 of the reflector 300) is fully reflective (i.e., 100% reflective, 0% transmissive). In some exemplary embodiments, the reflector 300 can be made of an organic material. In other embodiments, the reflector 300 can be made of an inorganic material to withstand the temperature processing of thin film transistor and color filter processes used to manufacture display panels. The first surface 302 and the third surface 306 of the reflector 300 may be coated with a reflective material (e.g., metal). The reflector 300 may be manufactured on a substrate (e.g., glass) having a planar surface so that the second surface 304 of the reflector 300 contacts the substrate. The second surface 304 of the reflector 300 may be rectangular. The first angle θ1 between the first surface 302 and the second surface 304 may be smaller than the second angle θ2 between the second surface 304 and the third surface 306.

[0054] In some exemplary embodiments, the total length L can be in the range between about 5 microns and about 250 microns. The reflector portion length D can be in the range between about 10 microns and about 230 microns. The first angle θ1 can be in the range between about 5 degrees and about 30 degrees. The second angle θ2 can be in the range between about 60 degrees and about 85 degrees. The width W can be in the range between about 2 microns and about 80 microns. In other embodiments, L, D, θ1, θ2 and W can have other suitable values ​​based on specific applications. The curvature R and / or slope distribution of the reflective surface can vary based on the specific application and the size of the reflector. In some exemplary embodiments, the reflector can include a single flat facet or multiple flat facets.

[0055] Fig. 6A 3 is a top view illustrating an exemplary reflective display 310. Reflective display 310 includes a plurality of pixels 312. The plurality of pixels 312 are arranged in rows and columns. Reflective display 310 can include any suitable number of rows and any suitable number of columns of pixels 312. In some exemplary embodiments, the number of rows is equal to the number of columns. In other embodiments, the number of rows is not equal to the number of columns.

[0056] Figure 6B is a cross-sectional view of an exemplary reflective display 310a. In this embodiment, the reflective display 310a includes a plurality of pixels 312a ( Figure 6B 310a). Each pixel 312a of the reflective display 310a includes a first substrate (e.g., a glass substrate) 314, a reflector array 300 disposed on the first substrate 314, a planarization layer 316 encapsulating the reflector array 300, a thin film device 318 (e.g., a thin film transistor) disposed on the planarization layer 316, a second substrate 322 (e.g., a glass substrate), and a liquid crystal layer 320 between the planarization layer 316 and the second substrate 322. In this embodiment, incident light as shown at 330 is redirected by the reflector 300 to a viewer as shown at 332. The reflector 300 redirects the incident light at an angle δ so that the reflected light 332 is perpendicular to the reflective display 310a.

[0057] Figure 6C is a cross-sectional view of an exemplary reflective display 310b. In this embodiment, the reflective display 310b includes a plurality of pixels 312b ( Figure 6C). Each pixel 312b of the reflective display 310b includes a first substrate (e.g., a glass substrate) 314, a reflector array 300 disposed on the first substrate 314, a thin film device 318 (e.g., a thin film transistor) disposed on the first substrate 314 close to (e.g., adjacent to) the reflector array 300, a second substrate 322 (e.g., a glass substrate), and a liquid crystal layer 320 between the first substrate 314 and the second substrate 322. It is worth noting that the reflective display 310b does not include a planarization layer, so that the reflector array 300 directly contacts the liquid crystal layer 320. When the height of the reflector 300 is sufficiently low (e.g., less than about 1 micron), the planarization layer can be excluded.

[0058] Fig.6D is a cross-sectional view of an exemplary reflective display 310c. In this embodiment, the reflective display 310c includes a plurality of pixels 312c ( Fig.6D ). Each pixel 312 c of the reflective display 310 c includes a first substrate (e.g., a glass substrate) 314, a reflector array 300 arranged on the first substrate 314, a second substrate 322 (e.g., a glass substrate), a thin film device 318 (e.g., a thin film transistor) arranged on the second substrate 322 opposite to the reflector array 300, and a liquid crystal layer 320 between the first substrate 314 and the second substrate 322.

[0059] Fig. 7A and Figure 7B 400 are top and side views of an exemplary reflective display. In this embodiment, pixel 400 is a fixed reflective display (such as Figure 2A Pixel 400 includes an active area 402 (eg, an area within the pixel that is driven by an applied electric field) and a reflector array 404. Each reflector 404 may be similar to that previously described with reference to Figure 5 300 as described and illustrated. Reflectors 404 are evenly arranged within pixel 400. In this embodiment, each reflector 404 includes a planar reflective first surface 406 (e.g., zero curvature). The first angle θ1 of each reflector 404 is equal to δ / 2. With the planar reflective surface 406, incident light is reflected in the direction of the viewer without any diffusion in the horizontal direction, such as Figure 7C The angular curve is shown as a single reflection point in the graph.

[0060] Fig. 8A 4 is a top view of a pixel 420 of another exemplary reflective display. In this embodiment, pixel 420 is a fixed reflective display (such as Figure 2APixel 420 includes an active area 422 and a reflector array 424. Each reflector 424 may be similar to that previously described with reference to Figure 5 4. The reflector 300 described and illustrated. The reflectors 424 are uniformly arranged within the pixel 420. In this embodiment, each reflector 424 includes a curved reflective first surface 426. The curved first surface 426 can be concave or convex. The reflector 424 can have a non-periodic shape, whose profile uses a sine function to diffuse light around a target viewing angle, and the slope can be designed to redirect light from the light source direction to the viewer direction.

[0061] Figure 8B Illustrated Fig. 8A An exemplary reflector 424 of FIG. 4 is shown, wherein L is approximately 21.5 microns, D is approximately 21.5 microns, θ1 is greater than approximately 4 degrees and less than approximately 11 degrees, θ2 is approximately 85 degrees, W is approximately 21.5 microns, the absolute value of R is greater than approximately 8 microns, and the tilt angle on W is less than approximately 25 degrees. With the curved reflective first surface 426, the incident light is reflected in the direction of the viewer and expanded in the horizontal direction, such as Figure 8C The angle curve is shown in the figure, corresponding to Figure 8B The reflector 424 reflects the light.

[0062] Fig. 9A 4 is a top view of a pixel 440 of another exemplary reflective display. In this embodiment, pixel 440 is a fixed reflective display (such as Figure 2A 420). The pixel 440 includes an active area 442 and a reflector array 424, as previously described. In this embodiment, the reflectors 424 are oriented at random angles within the pixel 420. Each reflector 424 includes a curved reflective first surface 426, as previously described. Each reflector 424 in the reflector array is arranged at an angle in the range between about 5 degrees and about 25 degrees to an immediately adjacent reflector in the reflector array. Fig. 9B An exemplary reflective display design is illustrated, wherein the reflectors 424 within each row are arranged to have rotation angles of approximately 0 degrees, approximately -20 degrees, approximately 0 degrees, approximately 20 degrees, approximately 0 degrees, etc., respectively. By changing the orientation of the reflectors 424, the top and bottom light diffusion in the horizontal direction remains substantially constant, as shown in FIG. Fig. 9CThe non-uniform arrangement of reflectors 424 minimizes undesirable visible moiré artifacts and optimizes the angular distribution of reflected light. Reflectors 424 can be connected or discrete structures. Reflectors 424 do not need to create a continuous film. In certain exemplary embodiments where reflectors 424 have random orientations relative to adjacent reflectors, discrete units may be desired. Reflectors 424 can have sharp edges or flat tops. The flat top allows for redirection of front light to the viewer. Fig.9D Another exemplary reflective display design is illustrated, in which the reflectors 424 in each row are arranged to have rotation angles of about 0 degrees, about -10 degrees, about 0 degrees, about 10 degrees, about 0 degrees, etc. With the curved reflective first surface 426, the incident light is reflected in the direction of the viewer and expanded in the horizontal direction, such as Fig.9E The angle curve is shown in the figure, corresponding to Fig.9D The reflector is arranged to reflect the light.

[0063] Fig. 10A 4 is a top view of another exemplary reflective display pixel 460. In this embodiment, pixel 460 is a fixed reflective display (such as Figure 2A Pixel 460 includes an active area 462 and a reflector array 424, as previously described. In this embodiment, each reflector 424 is oriented opposite to an adjacent reflector 424 within pixel 460 (e.g., Fig. 10A Each reflector 424 includes a curved reflective first surface 426, as previously described. Fig. 10B Examples include Fig. 10A 4 and 5. The exemplary reflectors 424 are shown arranged relative to each other. By orienting each reflector 424 opposite to the adjacent reflector, the light is diffused above and below in the horizontal direction, as shown in FIG. Fig. 10C To achieve the desired reflection behavior, the average slope of adjacent reflectors should be maintained.

[0064] Fig.11A 4 is a top view of a pixel 480 of another exemplary reflective display. In this embodiment, pixel 480 is a fixed reflective display (such as Figure 2A Pixel 480 includes an active area 482 and a reflector array 484. Each reflector 484 may be similar to that previously described with reference to Figure 5 Reflector 300 is described and illustrated. In this embodiment, reflectors 484 are uniformly arranged within pixel 480. Each reflector 484 includes a segmented reflective surface 486 consisting of a number of reflective facets distributed on the surface 486 at varying tilt angles along the W direction. Fig. 11B It is an example from Fig.11A Angular graph of an exemplary directional distribution of light reflected by a reflective display, wherein the reflector 484 includes an inclined polygonal prismatic first surface 486 (e.g., the tilt (slope) angles of the facet angles across W are plus or minus approximately 11.3 degrees, plus or minus approximately 8.7 degrees, and plus or minus approximately 4.8 degrees, L is approximately 22.5 microns, D is approximately 22.5 microns, θ1 is approximately 9.74 degrees, θ2 is approximately 85 degrees, and W is 21.5 microns). Fig. 11C It is an example from Fig.11A Angular graph of an exemplary directional distribution of light reflected by a reflective display, wherein reflector 484 includes a first surface 486 of a tilted asymmetric free-form prism shape (e.g., wherein L is approximately 22.5 microns, D is approximately 22.5 microns, θ1 is approximately 9.74 degrees, W is approximately 21.5 microns, the absolute value of R is less than approximately 255 microns and greater than approximately 5 microns, and the tilt angle across W is greater than approximately 4 degrees and less than approximately 40 degrees).

[0065] Fig. 12A 5 is a cross-sectional view of an exemplary reflector 500. The reflector 500 may be used to fix a reflective display such as Figure 2A 500 is a reflector array within each pixel of a fixed display 122 of the embodiment of the present invention. Each reflector 500 includes a first surface 504 having a first slope and a second surface 506 having a second slope different from the first slope. In this example, the slope of the first surface 504 is less than the slope of the second surface 506. In some exemplary embodiments, the first surface 504 and the second surface 506 may be curved (e.g., concave or convex). Each reflector 500 includes a first triangular portion and a second triangular portion, the first triangular portion including the first surface 504 and the second triangular portion including the second surface 506. Each reflector 500 also includes a third surface 508 extending between the first surface 504 and the second surface 506. In some exemplary embodiments, the third surface 508 is perpendicular to a substrate (not shown) on which each reflector 500 is arranged. The angle between the fourth (bottom) surface 510 of each reflector 500 and the first surface 504 may be in a range between about 5 degrees and about 15 degrees (e.g., 8 degrees). The angle between the fourth surface 510 and the second surface 506 of each reflector 500 can be in a range between about 15 degrees and about 25 degrees (e.g., 17 degrees). Each reflector 500 also includes a fifth surface 512 extending between the first surface 504 and the fourth surface 510. The fifth surface 512 can be perpendicular to the fourth surface 510.

[0066] Fig. 12B 5 is a cross-sectional view of an exemplary reflector 520. The reflector 520 may be used to fix a reflective display such as Figure 2A520). Each reflector 520 includes a first surface 524 having a first slope and a second surface 526 having a second slope different from the first slope. In this example, the slope of the first surface 524 is less than the slope of the second surface 526. The first surface 524 extends to the second surface 526. In certain exemplary embodiments, the first surface 524 and the second surface 526 may be curved (e.g., concave or convex). Each reflector 520 includes a single triangular portion including the first surface 524 and the second surface 526 on a single side of the reflector 520. Each reflector 520 also includes a third surface 528 extending to the second surface 526, and a fourth surface 530 extending between the third surface 528 and the first surface 524. The third surface 528 may be perpendicular to the fourth surface 530.

[0067] Compared to a reflector including a single slope, reflectors 500 and 520 including multiple slopes collect more light to be redirected to the viewer. The slopes can be configured based on given illumination conditions (e.g., the radiance of the light source) and the relative positions (fixed relative position or multiple relative positions) of the light source, display, and viewer to maximize the light in the viewer's field of view. Reflectors 500 and 520 can be configured for, e.g., FIG. 3B to FIG. 3F The reflectors 500 and 520 may be optimized for the particular illumination model shown and for a particular viewer's field of view (e.g., a cone angle of plus or minus approximately 30 degrees around the normal viewing direction). FIG. 3B to FIG. 3F Several relative positions of the emitting surface and the viewer shown in are optimized.

[0068] Return to reference Figure 3A , in certain use cases, a symmetric reflector may be desirable. Figure 3A Diffuse ambient light in the room is modeled. A Lambertian light source 140 illuminates (light 144) the front surface of a reflective display 142, which is arbitrarily rotated 60 degrees relative to the light source 140. A viewer 106 (eg, the viewer's head) may prevent normally incident light from illuminating the reflective display 142.

[0069] Fig.13A An exemplary array of inverted pyramid reflectors 600 is illustrated, and Fig. 13BAn exemplary inverted pyramid reflector 600 is illustrated. Each inverted pyramid reflector 600 includes a base portion 602 and a sidewall portion 604. The base portion 602 is transparent (e.g., at least about 85% of the ambient visible light incident on the base portion passes through the base portion) and the sidewall portion 604 is reflective (e.g., at least about 80% of the ambient visible light incident on the sidewall portion is reflected back to the viewer). The angle between the opposing sidewall portions 604 can be in the range between about 60 degrees and about 90 degrees. The inverted pyramid reflector 600 has a diffuse profile around the incident light direction 610. The light is reflected at a normal viewing angle, as shown at 612.

[0070] Fig. 13C is an example Fig.13A and Fig. 13B A graph of exemplary angular distribution of output coupled light intensity of an inverted pyramid reflector 600 of FIG. The graph illustrates the radiant intensity (in watts per steradian) of specular reflection, diffuse reflection, and inverted pyramid reflection versus angle (in degrees). In this embodiment, the ambient light comes from a diffuse ceiling, or from a horizontal plane in the case where the light comes from a diffuse wall. The angle between the plane of the reflective display and the ceiling (or wall) is approximately 90 degrees. Three reflectors are compared, including a specular reflector, a diffuse reflector, and an inverted pyramid reflector. For the inverted pyramid reflector, the light intensity in the normal direction toward the viewer is enhanced by approximately 120% relative to the diffuse reflector. For a display configuration at 90 degrees to the emitting surface, the reflected light is increased by approximately two times within a cone angle of approximately plus or minus 30 degrees around the normal viewing direction.

[0071] Fig.13D is an example Fig.13A and Fig. 13B A graph of exemplary angular distribution of output coupled light intensity of an inverted pyramid reflector 600 of FIG. The graph illustrates the radiant intensity (in watts per steradian) of specular reflection, diffuse reflection, and inverted pyramid reflection versus angle (in degrees). In this embodiment, ambient light comes from a diffuse ceiling, or from a horizontal plane in the case where the light comes from a diffuse wall. The angle between the plane of the reflective display and the ceiling (or wall) is approximately 60 degrees. Three reflectors are compared, including a specular reflector, a diffuse reflector, and an inverted pyramid reflector. For the inverted pyramid reflector, the light intensity in the normal direction toward the viewer is enhanced by approximately 33% relative to the diffuse reflector. Compared to a non-inverted pyramid shape, the inverted pyramid reflector allows an increase in the area for reflecting light in the desired direction, thereby increasing the overall intensity.

[0072] Fig.14A An exemplary array of inverted conical reflectors 620 is illustrated, and Fig. 14BAn exemplary inverted conical reflector 620 is illustrated. Each inverted conical reflector 620 includes a base portion 622 and a sidewall portion 624. The base portion 622 is transparent, and the sidewall portion 624 is reflective. The angle between the opposing sidewall portions 624 can be in a range between about 60 degrees and about 90 degrees. The inverted conical reflector 620 has a diffuse profile around an incident light direction 630. The light is reflected at a normal viewing angle, as shown at 632.

[0073] Fig. 14C is an example Fig.14A and Fig. 14B A graph of exemplary angular distribution of output coupled light intensity of an inverted conical reflector 620 of FIG. The graph illustrates the radiant intensity (in Watts / steradian) versus angle (in degrees) for specular reflection, diffuse reflection, and inverted conical reflection. In this embodiment, the ambient light comes from a diffuse ceiling, or from a horizontal plane in the case where the light comes from a diffuse wall. The angle between the plane of the reflective display and the ceiling (or wall) is approximately 60 degrees. Three reflectors are compared, including a specular reflector, a diffuse reflector, and an inverted conical reflector. For the inverted conical reflector, the light intensity in the normal direction toward the viewer is enhanced by approximately 33% relative to the diffuse reflector. Compared to a non-inverted conical reflector, the inverted conical reflector allows for an increased area to reflect light in the desired direction, thereby increasing the overall intensity.

[0074] Fig.15 Angular graphs illustrating the directional distribution of light reflection for several curved reflector designs are provided. Fig.15 It shows that when the incident angle of light is 30 degrees, the curvature radius of the curved reflective surface is Figure 5 The effect of a reflector constructed with a concave reflecting surface is shown. Fig.15 From left to right in the figure, the angular curves are for reflectors with a curvature radius R of (a) 264 μm, (b) 132 μm, (c) 88 μm, and (d) 66 μm. As shown in the figure, the light distribution in the vertical direction increases as the curvature radius of the reflector decreases, while the light distribution in the horizontal direction is roughly the same.

[0075] Fig.16This is reinforced by the graphs shown in , where the vertical and horizontal light distribution angles are plotted against the reflective efficiency. The vertical light distribution graph shows that for a radius of curvature of 264 μm, the distribution angle is approximately 20 degrees, with a peak reflective efficiency of approximately 3.4%. At the other extreme shown, the vertical light distribution angle is approximately 70 degrees, with a peak reflective efficiency of approximately 0.9% for a radius of curvature of 66 μm. The horizontal light distribution graph shows that for all radii of curvature, the distribution angle is approximately 10 degrees, with a peak reflective efficiency of approximately 3.4% for a radius of curvature of 264 μm and approximately 0.9% for a radius of curvature of 66 μm. Thus, changing the radius of curvature of the reflector results in a change in the light distribution in the vertical direction, but without any significant change in the horizontal direction.

[0076] The inventors have focused on increasing the angular uniformity of ambient light reflected from a reflector by adding light scattering features to the reflector to increase the light distribution, especially in a narrow (e.g., horizontal) direction. Surface roughness can be added to the reflective surface of the reflector to broaden and homogenize the reflected light. Roughening or providing microstructures on the reflective surface can increase the scattering of light reflected at the surface.

[0077] The light scattering properties of a reflective surface can be described by a Gaussian scattering function:

[0078] where θ is the angle with respect to the specular reflection direction, I(θ) is the radiance in the θ direction, I0 is the radiance in the specular direction, and σ is the standard deviation of the Gaussian distribution.

[0079] Fig.17 Included are graphs comparing the reflected light distribution from similarly constructed reflectors with a radius of curvature R of 264 μm. The left graph shows the light distribution of a reflector with a smooth surface, while the right graph shows the light distribution of a similar reflector with a rough surface. The parameters for surface roughness are σ = 0.2 radians (or 11.5 degrees) and the scatter fraction F = 1, where F = total scattered light power / total incident light. These parameters are related to the size and density of light scatter produced by the rough surface. As Fig.17 As seen in , a reflector with a rough surface provides a wider and more uniform light distribution than a reflector with a smoother surface.

[0080] Fig.18 Angular graphs illustrating the directional distribution of light reflection for several curved reflector designs are provided. Fig.18shows how the radius of curvature, in combination with the roughness at the reflective surface, affects the reflected light. The parameters defining a rough surface are a scattering factor σ = 0.2 radians (or 11.5 degrees) and a scattering fraction F = 1. In an alternative aspect, the scattering factor can be σ>0.3 degrees. In an alternative aspect, the scattering factor can be σ>3 degrees. In an alternative aspect, the scattering factor can be σ>6 degrees. In an alternative aspect, the scattering fraction can be F>0.6. In an alternative aspect, the scattering fraction can be F>0.7. In an alternative aspect, the scattering fraction can be F>0.8.

[0081] Fig.18 From left to right in the figure, the angular curves are for reflectors with a curvature radius R of (a) 264 μm, (b) 132 μm, (c) 88 μm, and (d) 66 μm. As shown in the figure, the light distribution in the vertical direction increases as the curvature radius of the reflector decreases, and the light distribution in the horizontal direction is roughly the same.

[0082] Fig.19 This is reinforced by the graphs shown in , which plot the vertical and horizontal light distribution angles versus reflective efficiency. The vertical light distribution graph shows that for distribution angles of about 70 degrees, and a wider distribution of about 0 degrees, the reflective efficiency ranges from 0.10 to 0.19 depending on the radius of curvature. The vertical graph also shows that for all radii of curvature, the reflective efficiency peaks at about 30 degrees, with a reflective efficiency as high as about 1.00%. This is similar to the reflector with the same radius of curvature. Fig.16 The horizontal light distribution graph shows a significantly wider distribution angle compared to the data for the . For all curvature radii, the horizontal distribution is shown to be about 80 degrees, with a reflection efficiency peak of about 1.7% for a curvature radius of 264 μm and about 0.9% for a curvature radius of 66 μm. Thus, roughening the reflective surface of the reflector provides a wider and more uniform light distribution than a smooth reflective surface of a reflector with the same curvature radius.

[0083] The reflectors disclosed herein can be manufactured using any suitable technique, including photolithography, micro-embossing, micro-machining, and embossing. A master stamp with the desired features can be produced. A varnish or any other suitable material can be applied to a glass substrate and then patterned or embossed with a stamp and cured. The resulting structure can then be metallized to increase its reflectivity.

[0084] The roughened reflective surface may be prepared by patterning, embossing, etching, mechanical abrasion, depositing particles, micromachining, or by using any other suitable technique.

[0085] Those skilled in the art will appreciate that modifications and variations may be made to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, it is contemplated that the present disclosure covers such modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A reflective display, comprising: a plurality of pixels, each pixel comprising an active area; as well as A reflector array, wherein the reflector array is within the active area of ​​each pixel, each reflector in the reflector array is directly adjacent to another reflector in the reflector array, each reflector in the reflector array is fully reflective, and each reflector in the reflector array includes a curved first surface.

2. The reflective display of claim 1, wherein the first surface is convex. The reflective display of claim 1 , wherein the first surface is concave.

4. The reflective display of claim 1, wherein each reflector in the array of reflectors comprises a planar second surface extending to the first surface. The reflective display of claim 4 , wherein the second surface is rectangular.

6. The reflective display according to claim 4, further comprising: a third surface extending between the first surface and the second surface, A first angle between the second surface and the first surface is smaller than a second angle between the second surface and the third surface.

7. The reflective display of claim 1, wherein each reflector in the reflector array is arranged at an angle in a range between about 15 degrees and about 25 degrees to an immediately adjacent reflector in the reflector array.

8. The reflective display of claim 1, wherein each reflector in the reflector array is arranged in an opposite orientation to an immediately adjacent reflector in the reflector array.

9. The reflective display according to claim 1, further comprising: Glass substrate; The reflector array is arranged on the glass substrate.

10. The reflective display according to claim 9, further comprising: A planarization layer encapsulates the reflector array.

11. The reflective display according to claim 9, further comprising: a liquid crystal layer within each pixel, The reflector array is in direct contact with the liquid crystal layer.

12. A reflective display, comprising: a plurality of pixels, each pixel comprising an active area; as well as A reflector array, wherein the reflector array is within the active area of ​​each pixel, each reflector in the reflector array is directly adjacent to another reflector in the reflector array, each reflector in the reflector array is fully reflective, and each reflector in the reflector array includes a first surface having a first slope and a second surface having a second slope different from the first slope.

13. The reflective display of claim 12, wherein each reflector in the reflector array comprises a third surface extending between the first surface and the second surface. The reflective display of claim 12 , wherein the first surface extends to the second surface.

15. The reflective display of claim 12, wherein each reflector in the reflector array comprises a first triangular portion comprising the first surface and a second triangular portion comprising the second surface.

16. The reflective display of claim 12, wherein each reflector in the reflector array comprises a single triangular portion including the first surface and the second surface on a single side of the reflector.

17. The reflective display of claim 12, wherein the first surface and the second surface are curved.

18. A reflective display, comprising: a plurality of pixels, each pixel comprising an active area; as well as An array of reflectors is within the active area of ​​each pixel, each reflector in the array of reflectors is directly adjacent to another reflector in the array of reflectors, and each reflector in the array of reflectors comprises an inverted pyramid or cone.

19. The reflective display of claim 18, wherein each reflector in the reflector array comprises a base portion and a sidewall portion, and Wherein the base portion is transparent and the side wall portion is reflective.

20. The reflective display of claim 19, wherein an angle between opposing sidewall portions is in a range between about 60 degrees and about 90 degrees.

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