Display system and backlight

Abstract

A display system including an optical element, a panel, and a backlight is provided. The backlight includes a substrate, at least one light source proximate the substrate, a first reflective layer on the substrate, and a patterned diffuser. The patterned diffuser includes at least one reflector positioned proximate to the light source. Each of the reflectors is aligned with a corresponding one or more of the light sources. The reflector has a minimum thickness and a maximum thickness greater than the minimum thickness. Light output from the backlight has an angular distribution defined by a full width at half maximum. The full width at half maximum is less than about 116 degrees. The optical element collects the light within a predetermined angle after the light is output from the backlight and passes through the panel, and the predetermined angle is less than about 20 degrees.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority under the Patent Laws to U.S. Provisional Application Serial No. 63 / 471,281, filed Jun. 6, 2023, the content of which is relied upon and incorporated herein by reference in its entirety. Technical Field

[0003] Embodiments generally relate to backlights, display systems having backlights, and methods of manufacturing the same, where the backlight has a patterned diffuser with a narrow - angle luminance distribution. Background Art

[0004] Liquid crystal displays (LCDs) are commonly used in various electronic products, such as cellular phones, laptop computers, electronic tablet computers, televisions, and computer monitors. An LCD is a light - valve - based display, where the display panel includes an array of individually addressable light valves. An LCD includes a backlight for generating light, which is then wavelength - converted, filtered, and / or polarized to produce an image.

[0005] There are edge - lit and direct - lit backlights. An edge - lit backlight includes an array of light - emitting diodes (LEDs) edge - coupled to a light guide plate, and the light guide plate emits light from its surface. A direct - lit backlight includes a two - dimensional (2D) LED array behind the LCD panel. Compared to edge - lit backlights, direct - lit backlights generally have the advantage of improved dynamic contrast. For example, a display with a direct - lit backlight can independently adjust the brightness of each LED to set the dynamic range of the image brightness. This is commonly referred to as local dimming.

[0006] To achieve the desired light uniformity and / or avoid hot spots in direct - lit backlights, polymer diffuser plates have been used, which are spaced a certain distance from the LEDs. In such configurations, the distance between the LEDs and the polymer diffuser plate is typically referred to as the optical distance. A larger optical distance and a thicker diffuser plate generally result in better uniformity. Thus, the overall display thickness of a display using a direct - lit backlight is typically greater than the overall display thickness of a display using an edge - lit backlight. Polymer diffuser plates typically have a thickness of 2.2 millimeters. Polymer diffuser plates with a thickness of 2.2 millimeters or more often suffer from thermal expansion problems. In addition, a polymer diffuser plate with a thickness of 2.2 millimeters typically results in a larger optical distance for the display system, which may lead to an increase in the amount of optical loss.

[0007] Some people have turned to thin diffuser sheets as an alternative to 2.2 - millimeter - thick polymer diffuser plates. However, in some applications, such as high - end LCD monitors and displays, which require higher image quality than other applications (such as television applications), a thin diffuser sheet is often not sufficient to achieve the desired performance level because of poor brightness uniformity and color uniformity. Thus, in practice, two thin diffuser sheets have been used, and the use of two diffuser sheets has led to an improvement in brightness uniformity and color uniformity. However, the use of two diffuser sheets results in a significant reduction in brightness efficiency. For example, by using two diffuser sheets, an efficiency reduction of up to 10% has been observed. This reduction in efficiency often leads to less consumer interest in displays using two diffuser sheets.

[0008] In addition, head - up displays (HUDs) are also used. These HUDs are transparent (or see - through) displays that can present images without the user having to shift their line of sight from tasks in the external world (e.g., the user can focus on the road ahead). HUDs also have the advantage that the user's eyes do not need to refocus between viewing the external world and the image added by the HUD. HUDs are used, for example, in commercial aircraft, automobiles, and other applications.

[0009] There are two types of HUD systems. One is a projection - based display, and the other is a reflection - based display. The projection - based HUD display uses LED lights or lasers to project useful information onto a dedicated section of a see - through surface (such as a windshield). HUD systems typically have a small field of view, and only the light concentrated within a smaller cone of vision is directed towards the user. In existing HUD systems, the light generated by the backlight is often allowed to spread over a wide range of angles, and only a small fraction of the light generated by the backlight is directed into the smaller cone of vision towards the user. For example, conventional mini - LED / LED backlight LCDs typically use a thick diffuser plate to convert a point - like light source into a uniform surface light source. After the thick diffuser plate, the uniform surface light source has a wide angular distribution, which cannot be collected by the reflection - type folding optics or the projection - type collection lens of the HUD system. Summary of the Utility Model

[0010] Based on the above problems, a backlight with a narrower angular distribution and higher brightness than conventional backlights using thick diffuser plates is needed. In various embodiments contemplated herein, a patterned diffuser is placed between one or more light sources and a panel such as an LCD panel. In the case of using a patterned diffuser, the light beam can be concentrated within a smaller angular range. This can be beneficial for applications such as HUD systems, where light must be received at optical elements within a narrow angular range, but it can also be beneficial for other applications. Additionally, compared to conventional HUD systems, the display systems discussed in various embodiments herein that utilize a patterned diffuser have higher optical efficiency and brightness. The display systems of the various embodiments discussed herein can achieve higher brightness levels, allowing the display systems to be effectively used during daytime peak hours and in bright areas. Further, in some embodiments, these display systems can have reduced energy usage and heat generation.

[0011] In some embodiments, the backlight does not have any polymer diffuser plates, but instead thin diffuser sheets can be used. These diffuser sheets can include two or more diffusing portions on opposite surfaces of the diffuser sheet. By using these diffuser sheets, the backlight can be manufactured in a more cost-effective manner and can be manufactured with higher alignment tolerances. A diffuser sheet having multiple diffusing portions can help improve the brightness efficiency of the backlight, thereby allowing such backlights to potentially be used in high-end LCD displays such as monitors.

[0012] In an exemplary embodiment, a display system is provided. The display system includes an optical element, a panel, and a backlight. The backlight includes a substrate, at least one light source proximate to the substrate, a first reflective layer on the substrate, and a patterned diffuser. The patterned diffuser includes at least one reflector positioned proximate to the light source. Each of the reflectors is aligned with one or more corresponding light sources among the light sources, and the reflector has a minimum thickness and a maximum thickness greater than the minimum thickness. The light output from the backlight has an angular distribution defined by the full width at half maximum, and the full width at half maximum is less than approximately 116 degrees. The optical element collects light within a predetermined angle after the light has output from the backlight and passed through the panel, and the predetermined angle is less than approximately 20 degrees.

[0013] In some embodiments, the full width at half maximum can be less than approximately 50 degrees. In some embodiments, the full width at half maximum can be less than approximately 25 degrees. In some embodiments, the full width at half maximum can be less than approximately 13.4 degrees.

[0014] In some embodiments, the panel can be a liquid crystal panel. In some embodiments, the display system can further include a color conversion layer. In some embodiments, the display system can further include a diffuser sheet. The diffuser sheet can include at least two diffusing portions, including a first diffusing portion and a second diffusing portion, and a light beam from a light source is configured to propagate through both the first diffusing portion and the second diffusing portion. Additionally, in some embodiments, the diffuser sheet can be positioned between the patterned diffuser and the light source.

[0015] In some embodiments, the display system can further include a prism film. Additionally, in some embodiments, the patterned diffuser can be positioned between the prism film and the panel. In some embodiments, the display system can further include a reflective polarizer. In some embodiments, the minimum thickness of the reflector can be at least about 13% of the maximum thickness of the reflector, and the minimum thickness of the reflector can be at most about 90% of the maximum thickness of the reflector.

[0016] In some embodiments, the patterned diffuser can include a carrier. The carrier can have a first side and a second side opposite the first side. The first side faces away from the light source, and the reflector is positioned on the first side of the carrier. Additionally, in some embodiments, the carrier can not have any volume diffusing components positioned on the second side of the carrier. Additionally, in some embodiments, the carrier can define a uniform diffusing pattern on the second side of the carrier.

[0017] In some embodiments, the reflector can define a minimum ink density and a maximum ink density, and the minimum ink density of the reflector can be at least about 13% of the maximum ink density of the reflector. Additionally, in some embodiments, the minimum ink density of the reflector can be at least about 40% of the maximum ink density of the reflector. Additionally, in some embodiments, the minimum ink density of the reflector can be between about 75% and about 90% of the maximum ink density of the reflector.

[0018] In another exemplary embodiment, a backlight is provided. The backlight includes a substrate, at least one light source adjacent to the substrate, a first reflective layer on the substrate, and a patterned diffuser. The patterned diffuser includes at least one reflector positioned adjacent to the light source. Each reflector in the reflectors is aligned with one or more corresponding light sources in the light sources. The reflector has a minimum thickness and a maximum thickness greater than the minimum thickness. The light output from the backlight has an angular distribution defined by a full width at half maximum, and the full width at half maximum is less than about 116 degrees. An optical element collects light within a predetermined angle after the light exits the backlight and passes through the panel, and the predetermined angle is less than about 20 degrees. In some embodiments, the full width at half maximum can be less than about 25 degrees. Additionally, in some embodiments, the full width at half maximum can be less than about 15 degrees.

[0019] In another exemplary embodiment, a method of manufacturing a display system is provided. The method includes positioning at least one light source proximate to a substrate, and positioning a first reflective layer proximate to the substrate. The method further includes positioning a patterned diffuser including at least one reflector proximate to the light source. Each reflector of the reflectors is positioned such that it is aligned with one or more corresponding light sources of the light sources. The reflector has a minimum thickness and a maximum thickness greater than the minimum thickness. The substrate, the light source, the first reflective layer, and the patterned diffuser form at least a portion of a backlight. The method further includes positioning a panel proximate to the backlight such that the panel is configured to receive light that has been output from the backlight. Additionally, the method includes positioning an optical element proximate to the panel such that the panel is configured to receive light that has been output from the panel. Light output from the backlight has an angular distribution defined by a full width at half maximum, and the full width at half maximum is less than about 116 degrees. The optical element collects light within a predetermined angle after the light has been output from the backlight and passed through the panel, and the predetermined angle is less than about 20 degrees.

[0020] In another exemplary embodiment, a display system is provided and the display system is manufactured by a process. The process includes positioning at least one light source proximate to a substrate. The process further includes positioning a first reflective layer proximate to the substrate, and positioning a patterned diffuser including at least one reflector proximate to the light source. Each reflector of the reflectors is positioned such that it is aligned with one or more corresponding light sources of the light sources. The reflector has a minimum thickness and a maximum thickness greater than the minimum thickness. The substrate, the light source, the first reflective layer, and the patterned diffuser form at least a portion of a backlight. The process further includes positioning a panel proximate to the backlight such that the panel is configured to receive light that has been output from the backlight. Additionally, the process includes positioning an optical element proximate to the panel such that the panel is configured to receive light that has been output from the panel. In the display system, light output from the backlight has an angular distribution defined by a full width at half maximum, and the full width at half maximum is less than about 116 degrees. The optical element receives light within a predetermined angle after the light has been output from the backlight and passed through the panel, and the predetermined angle is less than about 20 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0022] Figure 1 is a schematic diagram showing an exemplary head-up display (HUD) system in accordance with some embodiments discussed herein;

[0023] Figure 2A is a cross-sectional view showing an exemplary display system with a patterned diffuser in accordance with some embodiments discussed herein;

[0024] Figure 2Bis a cross-sectional view showing another exemplary display system according to some embodiments discussed herein, where the position of the patterned diffuser is different from that of the Figure 2A display having a patterned diffuser;

[0025] Figure 3A is a cross-sectional view showing another exemplary display according to some embodiments discussed herein, the display including a single diffuser sheet having only one diffusing portion;

[0026] Figure 3B is a cross-sectional side view showing a diffuser sheet having only one diffusing portion according to some embodiments discussed herein;

[0027] Figure 3C is a cross-sectional view showing another exemplary display system according to some embodiments discussed herein, the display system including two diffuser sheets, where each diffuser sheet includes only one diffusing portion;

[0028] Figure 4A is a cross-sectional view showing another exemplary display system according to some embodiments discussed herein, the display system including a single diffuser sheet having two diffusing portions on opposite sides of the diffuser sheet;

[0029] Figure 4B is a cross-sectional side view showing a diffuser sheet according to some embodiments discussed herein, the diffuser sheet having two diffusing portions on opposite sides of the diffuser sheet;

[0030] Figure 4C is a cross-sectional side view showing a diffuser sheet according to some embodiments discussed herein, the diffuser sheet having two diffusing portions on opposite sides of the diffuser sheet and having an adhesive layer disposed therein;

[0031] Figure 5A and Figure 5B is a cross-sectional view of an exemplary backlight including a patterned diffuser according to some embodiments discussed herein;

[0032] Figure 5C is according to some embodiments discussed herein Figure 5A a top view of an exemplary light source in a backlight portion of;

[0033] Figure 5D is according to some embodiments discussed herein Figure 5A a top view of an exemplary patterned diffuser of;

[0034] Figure 6 is a cross-sectional view of an exemplary backlight including a patterned diffuser according to some embodiments discussed herein;

[0035] Figure 7A-7Bis a cross-sectional view of an exemplary patterned diffuser in accordance with some embodiments discussed herein;

[0036] Figure 8A-8B is a cross-sectional view of another exemplary patterned diffuser having an encapsulation layer in accordance with some embodiments discussed herein;

[0037] Figure 9A-9B is a cross-sectional view of another exemplary patterned diffuser having reflectors on both sides of a carrier in accordance with some embodiments discussed herein;

[0038] Figure 10 is a graph showing the luminance of a display including a patterned diffuser in accordance with some embodiments discussed herein at different angles compared to a display using a 2.2 mm diffuser plate; Figure 3A compared to a display using a 2.2 mm diffuser plate;

[0039] Figure 11 is a graph showing the normalized angular luminance of a display using a patterned diffuser compared to a display using a 2.2 mm diffuser plate in accordance with some embodiments discussed herein;

[0040] Figure 12 is a graph showing the luminance obtained at various angles in accordance with some embodiments discussed herein, where a display system similar to Figure 2A is used, and where the luminance is measured before light passes through the optical film stack of the display system;

[0041] Figure 13 is a graph showing an example of how to calculate the full width at half maximum (FWHM) in accordance with some embodiments discussed herein; and

[0042] Figure 14 is a flowchart showing an exemplary method for manufacturing a display system in accordance with some embodiments discussed herein. DETAILED DESCRIPTION

[0043] Exemplary embodiments will now be described in more detail below with reference to the accompanying drawings, in which some but not all embodiments are shown. Like reference numerals generally refer to like elements throughout. Additionally, any connection or attachment can be direct or indirect unless otherwise specifically stated.

[0044] Figure 1FIG. 0 is a schematic diagram showing an exemplary head-up display (HUD) system 100. The HUD system 100 includes an image generation unit 102, a first optical element 106, a second optical element 108, and a windshield 110. The image generation unit 102 is configured to generate a light beam 104, and when the light beam 104 exits the image generation unit 102, this light beam 104 can define an angle 91. The light beam 104 is redirected away from the first optical element 106 towards the second optical element 108, and the light beam 104 is redirected away from the second optical element 108 towards the windshield 110. Once the light beam 104 reaches the windshield 110, the light beam 104 is reflected towards the observer 112. The light beam 104 is reflected towards the observer 112 such that the observer 112 perceives a projected image 114 as if the projected image 114 is located at a certain distance from the observer 112. This projected image 114 can include information such as navigation information, fuel information, vehicle speed, information about the music being played in the vehicle, etc.

[0045] The first optical element 106 and the second optical element 108 are Figure 1 mirrors in this case, but in other embodiments, these optical elements 106, 108 can be lenses or some other type of optical element. The second optical element 108 can be configured to be physically adjusted (e.g., rotated or otherwise reoriented) to adjust the path of the light beam 104. However, in other embodiments, the second optical element 108 may not be physically adjustable. In some embodiments, the first optical element 106 can be physically adjustable. The first optical element 106 has Figure 1 a straight shape in this case, while the second optical element 108 has a concave shape, but in other embodiments, these optical elements 106, 108 can have different shapes. For example, in other embodiments, the first optical element 106 can have a concave or convex shape, and in some embodiments, the second optical element 108 can have a convex or straight shape.

[0046] The HUD system 100 can be beneficial in avoiding the need for the user to have to change their viewing direction in order to locate the information they are seeking. Instead, this information can be presented in the user's natural viewing direction while driving. This can advantageously reduce driver distraction and lower the risk of accidents. Other components can be added to the HUD system 100.

[0047] In Figure 1In the HUD system 100, the first optical element 106 only collects light within a relatively narrow angular distribution. In some embodiments, the first optical element 106 only collects light with an angular distribution of less than about 20 degrees. Thus, it may be beneficial to emit light from the picture generation unit 102 such that the angle θ1 is relatively small and more light is focused within the narrow angular range. The various embodiments discussed herein provide diffusers in the backlight that help focus more light within the narrow angular range.

[0048] Figure 2A An exemplary display system 238 is shown, which can be used to focus a greater amount of light within a narrow angular range. In some embodiments, the display system 238 and other display systems described herein can act as a picture generation unit, which can, for example, replace Figure 1 the picture generation unit 102 to form a HUD. In some embodiments, the display system 238 can be a liquid crystal display (LCD). The display system 238 includes a backlight 242, which includes a patterned diffuser 222. Additionally, the display system 238 optionally includes a diffuser sheet 228 adjacent to the backlight 242. The diffuser sheet 228 and other diffuser sheets discussed herein can include polyethylene terephthalate (PET), polystyrene (PS), polymethyl methacrylate (PMMA), acrylic materials, and / or polycarbonate. Further, the diffuser sheet 228 can be provided in the form of a diffuser plate that acts as a volume diffuser, where light scattering and diffusion occur throughout the volume of the diffuser sheet 228. The diffuser sheet 228 can have a thickness of about 1 millimeter to about 3 millimeters. However, in some embodiments, the diffuser sheet 228 can alternatively be provided in the form of a surface diffuser, and light scattering and diffusion can occur at a portion near the surface of the diffuser sheet 228, and the surface diffuser can have a thickness of about 0.3 millimeters or less.

[0049] The light output from the backlight 242 has an angular distribution defined by the full width at half maximum. In some embodiments, this full width at half maximum can be less than about 116 degrees. However, in other embodiments, the full width at half maximum can be less than about 50 degrees, less than about 25 degrees, less than about 20 degrees, less than about 15 degrees, or even less than about 13.4 degrees.

[0050] The display system 238 can include a color conversion layer 230 adjacent to the diffuser sheet 228. In some embodiments, the color conversion layer 230 and other color conversion layers discussed herein can include a quantum dot film or a phosphor film. The display system 238 can include one or more prism films 232. In Figure 2AIn [the figure], a single prism film 232 is positioned adjacent to the color conversion layer 230 such that the color conversion layer 230 is located between the diffuser 228 and the prism film 232. The display system 238 may also include a reflective polarizer 234. The reflective polarizer 234 or any other reflective polarizer discussed herein reflects one polarization of light from the light sources 220A, 220B, 220C and transmits the other orthogonal polarization of the same light. It also reflects light such as ambient light to the observer, and this can reduce the perceived difference in the low-density and high-density regions on the reflector 226 of the patterned diffuser 222. In Figure 2A In [the figure], the reflective polarizer 234 is positioned adjacent to the prism film 232 such that the prism film 232 is located between the color conversion layer 230 and the reflective polarizer 234. However, in some embodiments, instead of or in addition to the prism film 232 and the reflective polarizer 234, a composite film may be provided, and the composite film may include materials that serve as the prism film 232 and the reflective polarizer 234. The display system 238 may also include a display panel 236. In Figure 2A In [the figure], the display panel 236 is positioned adjacent to the reflective polarizer 234 such that the reflective polarizer 234 is located between the prism film 232 and the display panel 236. In some embodiments, the reflective polarizer 234 may be bonded to the display panel 236. The diffuser 228, the color conversion layer 230, the prism film 232, and / or the reflective polarizer 234 may together form an optical film stack 245. The display panel 236 and other display panels described herein may be liquid crystal panels.

[0051] The display system 238 includes a substrate 216, where the substrate 216 defines a first surface 215A and a second surface 215B. The display system 238 also includes a plurality of light sources, where these light sources include a first light source 220A, a second light source 220B, and a third light source 220C. Although three light sources 220A - 220C are shown in Figure 2A In [the figure], any number of light sources may be utilized in the display system. The light sources 220A - 220C are each positioned adjacent to the first surface 215A of the substrate 216 rather than on the second surface 215B of the substrate 216. The light sources 220A - 220C are in contact with the first surface 215A of the substrate 216, but in other embodiments, the light sources 220A - 220C may be positioned differently relative to the substrate 216. Additionally, a reflective layer 218 is located at the first surface 215A of the substrate 216 and surrounds each of the light sources 220A, 220B, 220C. The substrate 216 may be positioned such that the first surface 215A of the substrate 216 faces the patterned diffuser 222.

[0052] The patterned diffuser 222 includes a reflector 226, and the reflector 226 includes a plurality of main reflector portions thereon, including a first main reflector portion 226A, a second main reflector portion 226B, and a third main reflector portion 226C. The reflector 226 also includes a secondary reflector portion 225 that covers the carrier portion not covered by the main reflector portions 226A-226C. The secondary reflector portion 225 has a reduced thickness relative to the main reflector portions 226A-226C. Although three main reflector portions 226A-226C are shown in Figure 2A , any number of main reflector portions can be utilized in a display system. The reflector 226 can be a patterned reflector. The main reflector portions diffuse more light and transmit less light diffusely than the secondary reflector portion. In Figure 2A , the reflector 226 can cover the entire first side 224A of the carrier 224. In this case, a portion of the light reflected between the reflector 226 and the reflective layer 218 can pass through the reflector 226 and extend toward the optical film stack 245. As Figure 5A shows, the secondary reflector portion 225 defines a thickness G. The thickness G can be the thickness of the secondary reflector portion 225 measured from the first side 224A of the carrier 224. As Figure 5A shows, the main reflector portions 226A-226C define a thickness H. The thickness H can be the maximum thickness of the main reflector portions 226A-226C measured from the first side 224A of the carrier 224. In some embodiments, the thickness G of the secondary reflector portion 225 can be between about 13% and about 90% of the thickness H of each main reflector portion 226A-226C.

[0053] As Figure 5A shows, the patterned diffuser 222 also has a minimum thickness B and a maximum thickness A greater than the minimum thickness B.

[0054] The reflector 226 can also define a minimum ink density and a maximum ink density, and the minimum ink density of the reflector 226 can be at least about 13% of the maximum ink density of the reflector 226. The ink density can be equal to the area of the ink droplet divided by the unit area, and in some cases, the unit area can be about 100 microns × 100 microns. However, in some embodiments, the minimum ink density of the reflector 226 can be at least about 40% of the maximum ink density of the reflector 226, and in some embodiments, the minimum ink density of the reflector 226 can be between about 75% and about 90% of the maximum ink density of the reflector 226.

[0055] Referring again to Figure 2A, the display system 238 further includes a carrier 224 having a first side 224A and a second side 224B. The carrier 224 is located in the display system 238 such that the first side 224A of the carrier 224 faces the diffuser sheet 228, the color conversion layer 230, the prism film 232, the reflective polarizer 234, and the display panel 236. Additionally, the carrier 224 is located in the display system 238 such that the second side 224B of the carrier 224 faces the light sources 220A - 220C, the reflective layer 218, and the substrate 216. The reflector 226 is positioned at the first side 224A of the carrier 224. The reflector 226 is in contact with the first side 224A of the carrier 224, but in other embodiments, the reflector 226 may be positioned differently relative to the carrier 224.

[0056] To maintain the alignment between the light sources 220A - 220C and the main reflector portions 226A - 226C of the reflector 226, it may be advantageous if the carrier 224 and the substrate 216 are made of the same or similar types of materials such that the reflector 226 and the light sources 220A - 220C are well-aligned with each other over a wide range of operating temperatures. Aligning the light sources 220A - 220C and the main reflector portions 226A - 226C may be beneficial for the proper operation of the backlight 242. In a particular illustrative embodiment, the carrier 224 and the substrate 216 are made of the same plastic material. In other embodiments, the carrier 224 and the substrate 216 are made of the same or similar types of glass.

[0057] In some embodiments, the substrate 216 may include a highly flexible material such that the light sources 220A - 220C on the carrier 224 and the substrate 216 can maintain alignment. The highly flexible substrate may be made of polyimide or another high-temperature resistant polymer film to allow component soldering. The highly flexible substrate may also be made of materials such as FR4 or fiberglass, but the substrate may have a much thinner thickness than normal. In a particular illustrative embodiment, a 0.4 - millimeter thick FR4 material may be used for the substrate 216, and the substrate 216 may be flexible enough to absorb dimensional changes caused by varying operating temperatures.

[0058] Figure 2B is a cross-sectional view of another exemplary display system 240, which may be an LCD. Figure 2B The display system 240 is similar to Figure 2A the display system 238 in several aspects, but Figure 2B the position of the patterned diffuser 222 in Figure 2A is different from that of the patterned diffuser 222 in Figure 2AThe display system 238, the display system 240 includes a substrate 216 defining a first surface 215A and a second surface 215B. The display system 240 further includes a reflective layer 218 positioned adjacent to the first surface 215A of the substrate 216, a first light source 220A, a second light source 220B, and a third light source 220C. The display system 240 further includes a diffuser sheet 228, a color conversion layer 230, a prism film 232, a reflective polarizer 234, and a display panel 236. The display system 240 includes a patterned diffuser 222, wherein the patterned diffuser 222 includes a carrier 224 defining a first side 224A and a second side 224B. A reflector 226 is positioned adjacent to the first side 224A.

[0059] In the display system 240, there is a diffuser sheet 228 positioned between the patterned diffuser 222 and the light sources 220A - 220C. The diffuser sheet 228 can take various forms, and any type of diffuser sheet described herein can be used in place of the diffuser sheet 228.

[0060] Each component of the display system 240 is similar to Figure 2A the corresponding component in the display system 238. However, relative to Figure 2A the position of the patterned diffuser 222 in Figure 2B the position of the patterned diffuser 222 is different in Figure 2B In Figure 2B , the patterned diffuser 222 is located between the prism film 232 and the reflective polarizer 234. Thus, the second side 224B of the carrier 224 faces the diffuser sheet 228, the color conversion layer 230, and the prism film 232, and the first side 224A of the carrier 224 faces the reflective polarizer 234 and the display panel 236.

[0061] Figure 3A is a cross - sectional view showing another exemplary display system 338A, the display system including a single diffuser sheet 328 having only one diffusing portion. The display system 338A can be an LCD. Except for the differences mentioned herein, the display system 338A generally functions in the same manner as Figure 2A the display system 238, and the discussion of the display system 238 in Figure 2A this article can also be applied to Figure 3A the display system 338A.

[0062] The display system 338A includes a backlight 342, which includes a patterned diffuser 322. Additionally, the display system 338A includes a diffuser sheet 328 in the backlight 342. The diffuser sheet 328 has a body 327 and a diffusing portion 329. The body 327 may include a polyethylene terephthalate (PET) material, and the diffusing portion 329 may include an acrylic resin mixed with diffuser particles of PMMA and / or polystyrene (PS). The diffuser sheet 328 may have a thickness of from about 0.2 mm to about 0.4 mm.

[0063] The diffuser sheet 328 is different from the diffuser sheet 228 described with reference to other figures. The diffuser sheet 228 may be provided in the form of a volume diffusing diffuser plate, where light scattering and diffusion occur throughout the volume of the diffuser sheet 228. In contrast, the diffuser sheet 328 may be a surface diffuser, and light scattering and diffusion may occur at portions near the surface of the diffuser sheet 328. Each of the diffuser sheet 328 and the diffuser sheet 228 includes a carrier, where the diffuser sheet 328 includes a carrier 324.

[0064] The reflector 326 has a first main reflector portion 326A, a second main reflector portion 326B, and a third main reflector portion 326C. The reflector 326 also has a secondary reflector portion 325. The secondary reflector portion 325 has a reduced thickness relative to the main reflector portions 326A - 326C, but the thickness of the secondary reflector portion 325 may be greater than zero. By having the reflector 326 over the entire first side 324A of the carrier 324, the display system 338A can hide variations in the patterned diffuser 322. This is because the difference in reflectivity near the secondary reflector portion 325 and the main reflector portions 326A - 326C may be small enough that the human eye cannot detect any difference. When the light sources 320A - 320C are turned off, the shape of the patterned diffuser is visible at certain viewing angles (e.g., at Figure 3A the viewing angle). However, using the secondary reflector portion 325 with a thickness greater than zero can also help hide the shape of the patterned diffuser. Additionally, the increase in the minimum thickness causes more light to spread along the patterned diffuser 322, and the thickness variation required to obtain uniform brightness is reduced.

[0065] In some embodiments, the reflector 326 can include two different layers, where the first layer has a constant thickness (e.g., the thickness of the sub-reflector portion 325), and where the second layer has a variable thickness. In some embodiments, when two different layers are utilized, the scattering properties of these layers may be different. Additionally or alternatively, when two different layers are utilized, the scattering properties of the two layers can vary gradually. For example, in such embodiments, the scattering properties can vary gradually at different points between a first location and a second location within the layer. In some embodiments, the scattering properties in the two layers can vary gradually, and the scattering properties at the interface between the two different layers can be the same or similar.

[0066] The far surface of the diffuser sheet 328 can be located at a first optical distance (OD1) away from the reflective layer 318. In some embodiments, it may be beneficial to use a diffuser sheet 328 with a relatively small thickness such that the first optical distance (OD1) is maintained at a relatively low value. By utilizing a lower optical distance, the amount of optical loss can be reduced.

[0067] In some embodiments, the display system 338A can include a color conversion layer 330 adjacent to the diffuser sheet 328, and the color conversion layer 330 can include a quantum dot film or a phosphor film. The display system 338A can include a prism film 332. In Figure 3A which, the prism film 332 is positioned adjacent to the color conversion layer 330 such that the color conversion layer 330 is located between the diffuser sheet 328 and the prism film 332. The display system 338A can also include a reflective polarizer 334. In Figure 3A which, the reflective polarizer 334 is positioned adjacent to the prism film 332 such that the prism film 332 is located between the color conversion layer 330 and the reflective polarizer 334. The display system 338A can also include a display panel 336. In Figure 3A which, the display panel 336 is positioned adjacent to the reflective polarizer 334 such that the reflective polarizer 334 is located between the prism film 332 and the display panel 336. In some embodiments, the reflective polarizer 334 can be bonded to the display panel 336. The diffuser sheet 328, the color conversion layer 330, the prism film 332, and / or the reflective polarizer 334 can together form an optical film stack 345A.

[0068] The display system 338A includes a substrate 316, where the substrate 316 defines a first surface 315A and a second surface 315B. The display system 338A also includes a plurality of light sources, where these light sources include a first light source 320A, a second light source 320B, and a third light source 320C. Although in Figure 3A315A, 315B, 316. In the embodiment of the present invention, three light sources 320A-320C are shown, but any number of light sources can be utilized in the display system. The light sources 320A-320C are each positioned adjacent to the first surface 315A of the substrate 316, rather than being positioned on the second surface 315B of the substrate 316. The light sources 320A-320C are in contact with the first surface 315A of the substrate 316, but in other embodiments, the light sources 320A-320C can be positioned differently relative to the substrate 316. In addition, a reflective layer 318 is located at the first surface 315A of the substrate 316 and surrounds each light source 320A, 320B, 320C. The substrate 316 can be positioned so that the first surface 315A of the substrate 316 faces the patterned diffuser 322.

[0069] The patterned diffuser 322 includes a reflector 326 thereon, and this reflector 326 includes a first main reflector portion 326A, a second main reflector portion 326B, and a third main reflector portion 326C. Figure 3A 326A-326C, but any number of primary reflector portions may be included in the display system. Reflector 326 also includes a secondary reflector portion 325, wherein the secondary reflector portion 325 covers portions of carrier 324 not covered by the primary reflector portions 326A-326C. Reflector 326 may be a patterned reflector.

[0070] Display system 338A also includes carrier 324, and carrier 324 has a first side 324A and a second side 324B. Carrier 324 is positioned in display system 338A such that first side 324A of carrier 324 faces diffuser 328, color conversion layer 330, prismatic film 332, reflective polarizer 334, and display panel 336. In addition, carrier 324 is positioned in display system 338A such that second side 324B of carrier 324 faces light sources 320A-320C, reflective layer 318, and substrate 316. Reflector 326 is positioned at first side 324A of carrier 324. Reflector 326 is in contact with first side 324A of carrier 324, but in other embodiments, reflector 326 may be positioned differently relative to carrier 324.

[0071] Figure 3B 3 is a cross-sectional side view showing a diffusion sheet 328 having only one diffusion portion 329. The diffusion sheet 328 may include a body 327 and a diffusion portion 329, and the diffusion portion 329 may extend along a surface of the body 327. Figure 3A In the embodiment, only a single diffuser 328 is included. However, in other embodiments, such as Figure 3C In the embodiment shown, multiple diffusers 328 may be used.

[0072] In some applications, such as high-end LCD monitors, which require higher image quality than other applications (such as TV applications), using only one diffuser sheet 328 in display system 338A may not be sufficient to achieve the desired levels of brightness uniformity and color uniformity. One way to address the brightness uniformity and color uniformity issues is to use two diffuser sheets, as Figure 3C shown. In Figure 3C , an exemplary display system 338B including two diffuser sheets is shown, where each diffuser sheet includes only one diffusing portion. By using two diffuser sheets, the brightness uniformity and color uniformity of display system 338B can be improved relative to Figure 3A display system 328A. However, in the case where a display system includes two or more diffuser sheets spaced apart from each other, the brightness efficiency typically decreases. For example, in the case of using multiple diffuser sheets, up to a 10% efficiency reduction is observed relative to other display systems using a single diffuser sheet (such as Figure 3A display system 328A). This decrease in brightness efficiency may make display system 338B less attractive to consumers.

[0073] Display system 338B can be an LCD. Except for the differences mentioned herein, display system 338B generally operates in the same manner as Figure 2A display system 238 and Figure 3A display system 338A, and the discussions herein regarding those display systems can also apply to Figure 3C display system 338B. For the sake of brevity, the discussions of features already discussed will not be repeated in the discussion of Figure 3C .

[0074] Display system 338B differs from Figure 2A display system 238 and Figure 3A display system 338A in that display system 338B includes a first diffuser sheet 328A and a second diffuser sheet 328B. Each of diffuser sheets 328A, 328B has a structure similar to that of diffuser sheet 328 as Figure 3B shown. The first diffuser sheet 328A includes a body 327A and a diffusing portion 329A, and the second diffuser sheet 328B further includes a body 327B and a diffusing portion 329B. Bodies 327A, 327B may include polyethylene terephthalate (PET) material, and diffusing portions 329A, 329B may include an acrylic resin mixed with diffuser particles of PMMA and / or polystyrene (PS). Diffuser sheets 328A, 328B form part of an optical film stack 345B. In as Figure 3CIn the case where multiple diffuser sheets are provided in the display system shown, the optical distance can be measured from the far surface of the diffuser sheet that is farthest from the reflective layer on the substrate. Thus, the display system 338B has a second optical distance (OD2), and this second optical distance (OD2) can be measured from the far surface of the second diffuser sheet 328B to the surface of the reflective layer 318.

[0075] In Figure 3C the display system 338B of, the first diffuser sheet 328A and the second diffuser sheet 328B are separated from each other by an air gap. At the surfaces of the first diffuser sheet 328A and the second diffuser sheet 328B facing the air gap, light may be reflected, and this reflection of light may cause additional light loss. This light loss can be reduced by eliminating the air gap between the diffuser sheets, and Figure 4A-4C the embodiments shown and discussed herein can be used to eliminate the air gap between the diffuser sheets.

[0076] Figure 4A is a cross-sectional view showing another exemplary display system 438, which includes a single diffuser sheet 428 having two diffusing portions. The display system 438 can be an LCD. By using one diffuser sheet 428 having two diffusing portions, an air gap within the diffuser sheet 428 can be avoided, the number of light reflections can be reduced, and the amount of light loss can be reduced. Except for the differences mentioned herein, the display system 438 generally functions in the same manner as the display systems described herein, and the discussion of other display systems can also be applicable to Figure 4A the display system 438 of.

[0077] The display system 438 includes a backlight 442, which includes a patterned diffuser 422. Additionally, the display system 438 includes a diffuser sheet 428 in the backlight 442. The far surface of the diffuser sheet 428 can be located at a third optical distance (OD3) away from the reflective layer 418, and this third optical distance (OD3) can be approximately equal to or less than Figure 3C the second optical distance (OD2) of the display 338B of. In Figure 4B other details regarding the diffuser sheet 428 are shown and further described herein.

[0078] In some embodiments, the display system 438 can include a color conversion layer 430 adjacent to the diffuser sheet 428, and the color conversion layer 430 can include a quantum dot film or a phosphor film. The display system 438 can include a prism film 432. In Figure 4A the prism film 432 is positioned adjacent to the color conversion layer 430 such that the color conversion layer 430 is located between the diffuser sheet 428 and the prism film 432. The display system 438 can also include a reflective polarizer 434. In Figure 4AIn FIG., the reflective polarizer 434 is positioned adjacent to the prism film 432 such that the prism film 432 is located between the color conversion layer 430 and the reflective polarizer 434. The display system 438 may further include a display panel 436. In Figure 4A FIG., the display panel 436 is positioned at the reflective polarizer 434 such that the reflective polarizer 434 is located between the prism film 432 and the display panel 436. In some embodiments, the reflective polarizer 434 may be bonded to the display panel 436. The diffuser sheet 428, the color conversion layer 430, the prism film 432, and / or the reflective polarizer 434 may together form an optical film stack 445.

[0079] The display system 438 includes a substrate 416, wherein the substrate 416 defines a first surface 415A and a second surface 415B. The display system 438 further includes a plurality of light sources, wherein the light sources include a first light source 420A, a second light source 420B, and a third light source 420C. Although Figure 4A FIG. shows three light sources 420A-420C, any number of light sources may be utilized in the display system. The light sources 420A-420C are each positioned adjacent to the first surface 415A of the substrate 416, rather than being positioned on the second surface 415B of the substrate 416. The light sources 420A-420C are in contact with the first surface 415A of the substrate 416, but in other embodiments, the light sources 420A-420C may be positioned differently relative to the substrate 416. Additionally, a reflective layer 418 is located at the first surface 415A of the substrate 416 and surrounds each of the light sources 420A, 420B, 420C. The substrate 416 may be positioned such that the first surface 415A of the substrate 416 faces the patterned diffuser 422.

[0080] The patterned diffuser 422 includes a reflector 426, wherein the reflector 426 includes a first main reflector portion 426A, a second main reflector portion 426B, and a third main reflector portion 426C. Although Figure 4A FIG. shows three main reflector portions 426A-426C, any number of main reflector portions may be utilized in the display system. The reflector 426 further includes a secondary reflector portion 425, wherein the secondary reflector portion 425 covers the portions of the carrier 424 that are not covered by the main reflector portions 426A-426C. The reflector 426 may be a patterned reflector.

[0081] The display system 438 further includes a carrier 424, and the carrier 424 has a first side 424A and a second side 424B. The carrier 424 is located in the display system 438 such that the first side 424A of the carrier 424 faces the diffuser 428, the color conversion layer 430, the prism film 432, the reflective polarizer 434, and the display panel 436. In addition, the carrier 424 is located in the display system 438 such that the second side 424B of the carrier 424 faces the light sources 420A - 420C, the reflective layer 418, and the substrate 416. The reflector 426 is positioned at the first side 424A of the carrier 424. The reflector 426 is in contact with the first side 424A of the carrier 424, but in other embodiments, the reflector 426 may be positioned differently relative to the carrier 424 (e.g., some optical adhesive may be located between the reflector 426 and the carrier 424).

[0082] In Figure 4B is shown in more detail Figure 4A the diffuser 428. Different from Figure 3B the diffuser 328, the diffuser 428 has two diffusing portions, including a first diffusing portion 429A and a second diffusing portion 429B. In the illustrated embodiment, the two diffusing portions 429A, 429B are located on opposite sides of the body 427. In the diffuser 428, a light beam from the light source can be configured to propagate (e.g., upward in Figure 4B ) through the second diffusing portion 429B, through the body 427, and through the first diffusing portion 429A. However, in other embodiments, the diffusing portions 429A, 429B may be positioned or oriented differently. Assuming the same transmission characteristics, the same haze characteristics, and the same material, the display system 438 has a higher brightness efficiency than the display system 338B (including two diffusers). In addition, compared with Figure 3A the display system 338A (which includes only a single diffuser 328 having only one diffusing portion 329), the display system 438 has enhanced brightness uniformity and color uniformity. However, the display system 438 may have a reduced efficiency relative to Figure 3A the efficiency of the display system 338A.

[0083] In Figure 4C is shown another diffuser 428A that has been anticipated. Different from Figure 4C the diffuser 428A, the diffuser 428A has a first diffusing portion 429A' and a second diffusing portion 429B'. However, the diffuser 428A includes a first body portion 427A and a second body portion 427B, and an adhesive layer 431 is positioned between the two body portions 427A, 427B. In some embodiments, the diffuser 428A can be formed by using Figure 3BTwo different diffuser sheets 328 and is formed by positioning a layer of deionized water 431 between the two diffuser sheets. The adhesive layer 431 can be configured to match the refractive indices of the two body portions 427A, 427B, and this can help reduce the amount of reflection at the adjacent surfaces of the two body portions 427A, 427B. In some embodiments, for testing purposes, deionized water is used in the adhesive layer 431, but various other materials can be used in the adhesive layer 431 instead of deionized water. The diffuser sheet 428A can be used to mimic Figure 4A the diffuser sheet 428. Assuming that the diffusing portions of the diffuser sheets have the same transmittance, the same haze characteristics, and the same film substrate material, the diffuser sheet 428 and the diffuser sheet 428A can have similar characteristics. In the diffuser sheet 428A, a light beam from a light source can be configured to propagate (e.g., upward in Figure 4C it) through the second diffusing portion 429B', through the second body portion 427B, through the adhesive layer 431, through the first body portion 427A and then through the first diffusing portion 429A'. The body portions 427A, 427B can include polyethylene terephthalate (PET) material, and the diffusing portions 429A', 429B' can include an acrylic resin mixed with diffuser particles of PMMA and / or polystyrene (PS).

[0084] The performance of various display systems is evaluated using a colorimeter. In the first test case, the performance of the display system 338A of Figure 3A is evaluated. In the second test case, the performance of the display system 338B of Figure 3C is evaluated. In the third test case, the performance of a display system similar to Figure 3C the display system 338B is evaluated, but the diffusing portions in the two diffuser sheets are located on opposite sides of each other and face away from each other. In the fourth test case, a display system similar to Figure 4A the display system 438 is used, but the display system includes the diffuser sheet 428A instead of the diffuser sheet 428.

[0085] When evaluating the performance of the display system, by employing the two diffuser sheets used in the Figure 3C display system 338B, and then positioning an adhesive layer including deionized water between the two diffuser sheets to form the diffuser sheet 428A. By doing so, the geometries of the diffuser sheets are made as similar as possible.

[0086] The Mura performance of different test cases is evaluated to identify whether problems of brightness non-uniformity and color non-uniformity may become issues. To evaluate this, the ΔE values for each different test case are obtained. The ΔE value can represent the color difference between a given position and the center of the LED region. Two colors in the given CIELAB color space and The CIE76 color difference ΔE value is equal to Generally, a ΔE value less than or equal to about 2 is desirable. In cases where the ΔE value exceeds about 2, Mura caused by luminance non-uniformity and color non-uniformity may be perceptible to the human eye, making the display system less appealing to the end user. The ΔE value is obtained by measuring in the central region of the backlight. Tests show that the first test case (where a single diffuser sheet with only one diffusing portion is used) has a maximum ΔE value of about 2.2, which is the maximum value among the test cases. Due to this maximum ΔE value of the first test case, the display system used in the first test case may have poor Mura performance caused by luminance non-uniformity and / or color non-uniformity, and this may be perceptible to the human eye. The second test case (where two diffuser sheets with only one diffusing portion are used, and where the diffusing portions are each on the same side of the diffuser sheet) has a maximum ΔE value of about 1.5, which is the lowest value among the test cases. Tests show that the third test case (where two diffuser sheets with only one diffusing portion are used, and where the diffusing portions are on opposite sides of each other) has a maximum ΔE value of about 1.5, which is the lowest value among the test cases. Additionally, tests show that the fourth test case (where diffuser sheet 428A is used) has a maximum ΔE value of about 1.7.

[0087]

[0088] The test results show that the maximum ΔE value of the fourth test case is about 77% of the maximum ΔE value of the first test case, which is a significant decrease. Additionally, the maximum ΔE value of the fourth test case is about 13% higher than the maximum ΔE values of the second and third test cases. The diffuser sheet 428A can be used to achieve a ΔE value below 2. Thus, in the case of using a display system with diffuser sheet 428A, any issues regarding luminance non-uniformity and / or color non-uniformity will likely not be perceptible to the human eye. Figure 4C

[0089] The relative luminance of different test cases was also evaluated. The relative luminance was obtained in the central region of the backlight. Tests show that the first test case (where a single diffuser sheet with only one diffusing portion is used) has the highest relative luminance of about 1.12. Tests show that the second test case (where two diffuser sheets with only one diffusing portion are used, and where the diffusing portions are each on the same side of the diffuser sheet) has a relative luminance of about 1.00, which is the lowest relative luminance among the test cases. Tests show that the third test case (where two diffuser sheets with only one diffusing portion are used, and where the diffusing portions are on opposite sides of each other) has a relative luminance of about 1.00. Additionally, tests show that the fourth test case (where diffuser sheet 428A is used) has a relative luminance of about 1.04. ​

[0090]

[0091] These test results show that the brightness of the fourth test case is about 4% higher than the brightness of the second and third test cases. However, the brightness in the fourth test case is about 93% of the brightness in the first test case.

[0092] There is usually a trade-off between brightness efficiency and uniformity (in terms of both brightness uniformity and color uniformity). However, the results in Tables 1 and 2 demonstrate that the brightness efficiency of the fourth use case (where diffuser sheet 428A is used) is 4% higher than that of the second and third use cases, while the uniformity is not significantly reduced.

[0093] Figure 5A and Figure 5B Other details regarding an exemplary backlight are shown in and. The backlight 242 includes a patterned diffuser. The backlight 242 may include a substrate 216, a reflective layer 218, light sources 220A - 220C, and a patterned diffuser 222. The backlight 242 may further include a diffuser sheet 228, a color conversion layer 230, a prism film 232, and a reflective polarizer 234. The patterned diffuser 222 includes a carrier 224 (e.g., a light guide plate) and a reflector 226. A plurality of light sources 220A - 220C are disposed on the substrate 216 and are in electrical communication with the substrate 216. The reflective layer 218 is on the substrate 216 and surrounds each of the light sources 220A - 220C. In a particular exemplary embodiment, the substrate 216 may be reflective, such that the reflective layer 218 may be excluded. The patterned diffuser 222 is adjacent to the light sources 220A - 220C and is optically coupled to each of the light sources 220A - 220C. In a particular exemplary embodiment, an optical adhesive (not shown) may be used to couple the light sources 220A - 220C to the patterned diffuser 222. The refractive index of the optical adhesive (e.g., phenyl silicone resin) may be greater than or equal to the refractive index of the carrier 224.

[0094] The carrier 224 and other carriers discussed herein may include glass, but these carriers may include other materials. The patterned diffuser 222 may include a reflector 226 positioned at a first side 224A of the carrier 224. In some embodiments, the patterned diffuser 222 may be provided at a second side 224B of the carrier 224 without any volume diffuser components, but in other embodiments, a volume diffuser component having a uniform diffuser pattern or some other pattern may be provided at the second side 224B of the carrier 224.

[0095] According to Snell's law, the carrier surface can refract light in air from the light source into the carrier. For example, in Figure 5AIn this case, light can be emitted from light sources 220A - 220C at an incident angle of 70 degrees with respect to the plane defined by the second side 224B. Once the light enters the carrier 224, the incident angle of the light becomes smaller. For example, in the case where the carrier 224 comprises a glass material with a refractive index of 1.5, the refraction angle at the second side 224B becomes approximately 38.79 degrees. The smaller the change in the incident angle, the greater the alignment tolerance may be.

[0096] As Figure 5A shown, the patterned diffuser 222 defines a maximum thickness A, where the maximum thickness A is measured from the second side 224B of the carrier 224 to the position on the surface of the main reflector portion (e.g., the main reflector portion 226a) that is farthest from the second side 224B. The carrier 224 may define a minimum thickness B, where the minimum thickness B is measured from the first side 224A of the carrier 224 to a position on the surface of the secondary reflector portion (e.g., the secondary reflector portion 225). In some embodiments, the carrier 224 and other carriers described herein may comprise a glass material, but these carriers may equally comprise other materials.

[0097] Each of the light sources 220A - 220C can emit peak intensity light along the normal axis. For example, the first light source 220A emits peak intensity light 242A along an axis perpendicular to the first light source 220A, the second light source 220B emits peak intensity light 242B along an axis perpendicular to the second light source 220B, and the third light source 220C emits peak intensity light 242C along an axis perpendicular to the third light source 220C.

[0098] The reflector 226 is disposed on the first side 224A of the carrier 224. The reflector 226 is aligned with the light sources 220A - 220C. The reflector 226 has main reflector portions 226A - 226C, and each of the main reflector portions 226A - 226C is aligned with the corresponding light source among the light sources 220A - 220C. As Figure 5AAs shown, each of the main reflector portions 226A - 226C includes a thickness profile along the width or diameter of the reflector 226, the thickness profile including an enlarged section 244B and a transition section 244A extending from and surrounding the enlarged section 244B. The enlarged section 244B of the main reflector portion has a thickness H, and this thickness H can be the average thickness of the enlarged section 244B. In some embodiments, the enlarged section 244B can be substantially flat, and in some embodiments, the transition section 244A can be curved. The enlarged section 244B can have a rough surface profile. For example, the enlarged section 244B can have slight variations in thickness across the thickness of the entire enlarged section 244B. In a particular illustrative embodiment, the thickness variation of the enlarged section 244B does not exceed plus or minus 20% of the average thickness of the enlarged section 244B. The average thickness can be measured in a direction orthogonal to the carrier 224 by adding the maximum thickness (T max ) and the minimum thickness (T min ) of the enlarged section 244B, and then dividing this sum by two (i.e., (T max +T min ) / 2). For example, for an average thickness of the enlarged section 244B of about 100 microns, the maximum thickness of the enlarged section 244B will be equal to or less than about 120 microns, and the minimum thickness of the enlarged section 244B will be equal to or greater than about 80 microns. In other embodiments, the thickness variation of the enlarged section 244B does not exceed plus or minus 15% of the average thickness of the enlarged section 244B. For example, for an average thickness of the enlarged section 244B of about 80 microns, the maximum thickness of the enlarged section 244B will be equal to or less than about 92 microns, and the minimum thickness of the enlarged section 244B will be equal to or greater than about 68 microns. In other embodiments, the thickness variation of the enlarged section 244B does not exceed plus or minus 10% of the average thickness of the enlarged section 244B. For example, for an average thickness of the enlarged section 244B of about 50 microns, the maximum thickness of the enlarged section 244B will be equal to or less than about 55 microns, and the minimum thickness of the enlarged section 244B will be equal to or greater than about 45 microns. In other embodiments, the thickness variation of the enlarged section 244B does not exceed plus or minus 5% of the average thickness of the enlarged section 244B.

[0099] The slope of the transition section 244A can be defined as the absolute ratio of the thickness change to the distance change from the center of each main reflector portion 226A - 226C. The slope of the transition section 244A can vary at different distances from the center of each main reflector portion 226A - 226C. In a particular illustrative embodiment, the slope is maximum near the amplification section 244B, rapidly decreases as the distance from the center of each main reflector portion 226A - 226C increases, and then slowly decreases as the distance from the center of the main reflector portions 226A - 226C increases.

[0100] Each amplification section 244B can have a width C (in the case where the amplification section 244B is circular, the width can be the diameter of the amplification section 244B), and this width C can be measured in a plane parallel to the first side 224A of the carrier 224. Additionally, each of the light sources 220A - 220C has a width E (in the case where each of the light sources 220A - 220C is circular, the width can be the diameter of the light source 220A - 220C), and this width E can be measured in a plane parallel to the first side 215A of the substrate 216. The width C of the amplification section 244B can be greater than the width E of each corresponding light source among the light sources 220A - 220C. However, the width C of each amplification section 244B can be less than the product of a predetermined value and the width E of each corresponding light source among the light sources 220A - 220C. In a particular illustrative embodiment, when the width E of each of the light sources 220A - 220C is greater than or equal to about 0.5 millimeters, the predetermined value can be about 2 or about 3, such that the width C of each amplification section 244B is less than about 2 or about 3 times the width E of each of the light sources 220A - 220C. When the width E of each of the light sources 220A - 220C is less than 0.5 millimeters, the predetermined value can be determined by the alignment ability between the light sources 220A - 220C and the main reflector portions 226A - 226C, such that the width C of each amplification section 244B of each of the main reflector portions 226A - 226C can be in a range of approximately 100 microns to about 300 microns greater than the width E of each of the light sources 220A - 220C. Each amplification section 244B can be large enough such that each of the main reflector portions 226A - 226C can be aligned with the corresponding light source, and small enough to achieve suitable brightness uniformity and color uniformity.

[0101] In a plane parallel to the first side 224A of the carrier 224, each of the main reflector portions 226A - 226C may have a width D. In the case where the main reflector portions 226A - 226C have a circular shape, the width D may be the diameter of the main reflector portions 226A - 226C. However, the main reflector portions 226A - 226C may have other shapes. Each of the light sources 220A - 220C may be separated by a spacing F. The spacing F may be, for example, about 90, 45, 30, 10, 5, 2, 1, or 0.5 millimeters, greater than about 90 millimeters, or less than about 0.5 millimeters. In a particular illustrative embodiment, the ratio D / F of the width D of each of the main reflector portions 226A - 226C to the spacing F may be in the range between about 0.45 and 1.0. The ratio may vary with the spacing F of the light sources 220A - 220C and the distance between the emission surface of each of the light sources 220A - 220C and the corresponding reflector 226. For example, when the spacing F is equal to about 5 millimeters and the distance between the emission surface of each of the light sources 220A - 220C and the corresponding main reflector portion of the main reflector portions 226A - 226C is equal to about 0.2 millimeters, the ratio may be equal to about 0.50, 0.60, 0.70, 0.80, 0.90, or 1.0.

[0102] The reflector 226 reflects at least a portion of the light emitted from the light sources 220A - 220C into the carrier 224. The reflector 226 has specular reflection and diffuse reflection, and these characteristics may vary depending on the different positions within the main reflector portions 226A - 226C and the secondary reflector portion 225. The specularly reflected light exits from the second side 224B of the carrier 224. Although the specularly reflected light mainly propagates laterally due to the reflection between the reflective layer 218 and the carrier 224 or due to the reflection between the reflective layer 218 and the color conversion layer 230 (see Figure 5A ) or the diffuser sheet 228 (see Figure 2A ), some light loss may occur due to the incomplete reflection from the reflective layer 218. Figure 2A )

[0103] The diffused light has an angular distribution between 0 degrees and 90 degrees measured from the normal of the carrier 224. Approximately 50% of the diffused light has an angle exceeding the critical angle of total internal reflection (θ TIR ). Therefore, the diffused light can propagate laterally without any loss due to total internal reflection until the light is subsequently extracted from the carrier 224 by the reflector 226.

[0104] In some embodiments, the substrate 216 can be a printed circuit board (PCB), a glass or plastic substrate, or another suitable substrate for transmitting electrical signals to each of the light sources 220A - 220C such that each light source can be individually controlled. The substrate 216 can be a rigid substrate or a flexible substrate. For example, the substrate 216 can include flat glass or curved glass. For example, the curved glass can have a radius of curvature less than about 2000 millimeters, such as about 1500, 1000, 500, 200, or 100 millimeters. The reflective layer 218 can include, for example, a metal foil such as silver, platinum, gold, copper, etc. The reflective layer 218 can include, for example, a dielectric material such as a polymer like polytetrafluoroethylene (PTFE). The reflective layer 218 can include a porous polymer material such as polyethylene terephthalate (PET), PMMA, polyethylene naphthalate (PEN), polyethersulfone (PES), etc. Additionally, the reflective layer 218 can include a multilayer dielectric interference coating or a reflective ink including white inorganic particles such as titanium dioxide, barium sulfate, or other materials suitable for reflecting light and tuning the color of the reflected and transmitted light, such as colored pigments.

[0105] Each of the light sources 220A - 220C can be, for example, an LED (e.g., width E greater than about 0.5 millimeters), a mini - LED (e.g., width E between about 0.1 millimeters and about 0.5 millimeters), a micro - LED (e.g., width E less than about 0.1 millimeters), an organic LED (OLED), or another suitable light source having a wavelength in the range from about 400 nanometers to about 750 nanometers. In other embodiments, each of the plurality of light sources 220A - 220C can have a wavelength shorter than 400 nanometers and / or longer than 750 nanometers. Light from each of the light sources 220A - 220C can be optically coupled to the carrier 224. As used herein, the term "optically coupled" is intended to mean that the light source is located near the surface of the carrier and is in optical communication with the carrier directly or through an optically transparent adhesive so as to introduce light into the carrier, and the light propagates at least in part due to total internal reflection. Light from each of the light sources 220A - 220C is optically coupled to the carrier 224 such that a first portion of the light propagates laterally in the carrier 224 due to total internal reflection and is extracted from the carrier by the reflector 226, and a second portion of the light propagates between the reflective layer 218 and the reflector 226 due to multiple reflections at the reflective surfaces of the reflective layer 218 and the reflector 226 (or between the optical film stack 245 (see Figure 2A )) and the reflective layer 218). For example, as Figure 5BAs shown, light ray 217 can be emitted from the first light source 220A, and the light ray 217 can be reflected away from the reflector 226 at the first main reflector portion 226A and away from the reflective surface of the reflective layer 218. The light ray 217 is shown only as an example, and other light rays emitted from the first light source 220A can be reflected a different number of times by the reflective surfaces of one or more reflectors 226 and / or the reflective layer 218.

[0106] According to various embodiments, the carrier 224 can include any suitable transparent material for lighting and display applications. As used herein, the term "transparent" is intended to mean that the carrier has a light transmittance of greater than about 70% over a length of 500 millimeters in the visible region of the spectrum (from about 420 - 750 nanometers). In certain embodiments, the exemplary transparent material has a transmittance of greater than about 50% in the ultraviolet (UV) region (from about 100 - 400 nanometers) over a length of 500 millimeters. According to various embodiments, for wavelengths ranging from about 450 nanometers to about 650 nanometers, the carrier can include an optical transmittance of at least 95% over a path length of 50 millimeters.

[0107] The optical properties of the carrier 224 are affected by the refractive index of the transparent material. According to various embodiments, the carrier 224 can have a refractive index ranging from about 1.3 to about 1.8. In other embodiments, the carrier 224 can have a relatively low level of light attenuation (e.g., due to absorption and / or scattering). For example, the light attenuation of the carrier 224 can be less than about 5 decibels per meter for a wavelength range of about 420 - 750 nanometers. The carrier 224 described herein and other carriers can include polymeric materials such as plastics (e.g., PMMA, methyl methacrylate styrene (MS), polydimethylsiloxane (PDMS)), polycarbonate (PC), or other similar materials. The carrier 224 can also include glass materials such as aluminosilicate, alkali metal aluminosilicate, borosilicate, alkali metal borosilicate, aluminoborosilicate, alkali metal aluminoborosilicate, soda lime, or other suitable glasses. Non - limiting examples of commercially available glasses suitable for use as the glass carrier 224 include EAGLE Lotus TM 、 Iris TM and glass. In an example where the substrate 216 includes curved glass, the carrier 224 can also include curved glass to form a curved backlight. In other embodiments, the carrier 224 can have a relatively high level of light attenuation. For example, the light attenuation of the carrier 224 can be greater than about 5 decibels per meter for a wavelength range of about 420 - 750 nanometers.

[0108] Figure 5C is Figure 5ATop view of exemplary light sources 220A - 220I in the backlight. The light sources include a first light source 220A, a second light source 220B, a third light source 220C, a fourth light source 220D, a fifth light source 220E, a sixth light source 220F, a seventh light source 220G, an eighth light source 220H, and a ninth light source 220I. The light sources 220A - 220I are located on a substrate 216 (see Figure 5A ), where a reflective layer 218 surrounds the light sources 220A - 220I. The light sources 220A - 220I are arranged in a 2D array including multiple rows and multiple columns. Although nine light sources are shown in Figure 5C as a three - row and three - column arrangement, in other embodiments, any suitable number of light sources 220A - 220I can be used, where the light sources 220A - 220I are arranged in any suitable number of rows and any suitable number of columns. The light sources 220A - 220I can also be arranged in other periodic patterns, such as a hexagonal or triangular grid, or in a quasi - periodic or non - strictly periodic pattern. For example, the spacing between the light sources 220A - 220I can be smaller at the edges and / or corners of the backlight.

[0109] Figure 5D is a top view in which a reflector 226 is shown on a carrier 224. The reflector 226 includes a first main reflector portion 226A, a second main reflector portion 226B, a third main reflector portion 226C, a fourth main reflector portion 226D, a fifth main reflector portion 226E, a sixth main reflector portion 226F, a seventh main reflector portion 226G, an eighth main reflector portion 226H, and a ninth main reflector portion 226I. A secondary reflector portion 225 can cover the remaining portion of the carrier 224 (see Figure 5B ), where there are no main reflector portions 226A - 226I in the remaining portion, and the secondary reflector portion 225 has a reduced thickness relative to the main reflector portions 226A - 226I. Each of the main reflector portions 226A - 226I includes an enlarged section 244B and a transition section 244A. The enlarged section 244B can be more reflective than the transition section 244A, and the transition section 244A can be more transmissive than the enlarged section 244B. Each transition section 244A can have characteristics that vary in a continuous and smooth manner at a greater distance from the enlarged section 244B. Although each of the main reflector portions 226A - 226I is circular in the embodiment shown in Figure 5D , each main reflector portion can have another suitable shape (e.g., oval, rectangle, hexagon, etc.). Since the reflector 226 is directly fabricated on the upper surface of the carrier 224, the reflector 226 increases the ability to hide the light sources 220A - 220I (see Figure 5C ). Fabricating the reflector 226 directly on the upper surface of the carrier 224 also saves space.

[0110] In certain illustrative embodiments, each of the main reflector portions 226 - 226I may be more similar to a diffuser such that each of the main reflector portions 226A - 226I further enhances the performance of the backlight 242 by scattering some of the light at a high enough angle such that they can propagate in the carrier 224 by total internal reflection. Such light will not undergo multiple bounces between the reflector 226 and the reflective layer 218 (see Figure 2A ) or between the optical film stack and the reflective layer 218, and thus avoids loss of optical power and improves backlight efficiency. In certain illustrative embodiments, each of the main reflector portions 226A - 226I acts more like a specular reflector. In other embodiments, some regions of the main reflector portions 226A - 226I may have more diffusive reflection characteristics while some regions may have more specular reflection characteristics.

[0111] The reflector 226 can be formed, for example, by printing (e.g., inkjet printing, screen printing, microprinting, etc.) a pattern with white ink, black ink, metallic ink, or other suitable ink. The reflector 226 can also be formed by first depositing a continuous layer of white or metallic material, e.g., by physical vapor deposition (PVD) or any number of coating techniques such as slot die coating or spraying, and then patterning the layer by lithography or other known area - selective material removal methods. The reflector 226 can also be formed by other known methods of selectively removing material from the carrier 224 itself, e.g., by laser ablation or chemical etching into the carrier 224.

[0112] In certain illustrative embodiments, the light sources 220A - 220I (see Figure 5C ) can be white light sources, and the presence of different reflective and absorptive materials in the reflector 226 at variable densities may be beneficial in minimizing color shift over each darkened region of the backlight. Multiple bounces of light between the reflector 226 and the reflective layer 218 (see Figure 5A ) can cause the red part of the spectrum to lose more light than the blue part, or vice versa. In this case, the reflection can be designed to be a neutral color, e.g., by using light - colored reflective / absorptive materials or materials with opposite dispersion signs (where dispersion means the spectral dependence of reflection and / or absorption), to minimize color shift. When using a white light source, it may also be beneficial for the reflector 226 to reflect and transmit similar amounts of blue light as green and red light. The reflector 226 can contain micron - sized particles larger than a threshold size. For example, the threshold size can be about 140 nanometers for titanium dioxide, about 560 nanometers for aluminum oxide, or about 750 nanometers for sodium fluoride. In other examples, the threshold size can be 1, 2, 5, 10, or 20 microns.

[0113] In certain illustrative embodiments, the light sources 220A - 220I (see Figure 5C ) can be blue light sources. In the case of using a blue light source, it may be beneficial for the reflector 226 to reflect more blue light than green and red light and transmit less blue light than green and red light. The reflector 226 can include nanoscale particles smaller than a threshold size. For example, the threshold size can be about 140 nanometers for titanium dioxide, about 560 nanometers for aluminum oxide, or about 750 nanometers for sodium fluoride. The patterned diffuser 222 can have a spatially varying transmittance or a spatially varying color shift.

[0114] Several different embodiments of the patterned diffuser are contemplated herein, and Figure 6 a portion of an exemplary backlight including the patterned diffuser 622 is shown. Also shown is a reflector 626, where the reflector 626 has a first main reflector portion 626A, a second main reflector portion 626B, and a third main reflector portion 626C. The reflector 626 also includes a secondary reflector portion 625. In Figure 6 , a first light source 620A, a second light source 620B, and a third light source 620C are also shown. Figure 6 The components shown in Figure 2A are similar in most respects to the components described and shown in reference Figure 5A-5D . However, in Figure 6 , the reflector 626 faces the light sources 620A - 620C. In Figure 6 , as previously described, includes a substrate 616, a reflective layer 618, and light sources 620A - 620C. In this embodiment, the patterned diffuser 622 includes a carrier 624 (e.g., a light guide plate), the carrier 624 having a first side 624A and a second side 624B opposite the first side 624A. The reflector 626 is on the second side 624B of the carrier 624, and the second side 624B of the carrier 624 faces the plurality of light sources 620A - 620C. Additionally, the substrate 616 defines a first surface 615A and a second surface 615B, and the light sources 620A - 620C are each positioned adjacent to the first surface 615A.

[0115] Figure 7A-7B is a cross - sectional view of exemplary patterned diffusers 722, 722'. In Figure 7A 's patterned diffuser 722, the patterned diffuser 722 includes a carrier 724 defining a first side 724A and a second side 724B. The patterned diffuser 722 is generally similar to reference figures 2, Figure 5A-5DOther patterned diffusers are described and shown, but the patterned diffuser 722 also includes a diffuser layer 752. In some embodiments, the diffuser layer 752 is positioned adjacent to the second side 724B of the carrier 724, and the diffuser layer 752 can be directly attached to the second side 724B of the carrier 724. A reflector 726 is provided. The reflector 726 includes a first main reflector portion 726A, a second main reflector portion 726B, and a third main reflector portion 726C. The reflector 726 also includes a secondary reflector portion 725. The reflector 726 is positioned adjacent to the first side 724A of the carrier 724, and the reflector 726 can operate similar to other reflectors described herein. In some embodiments, the reflector 726 can be directly attached to the first side 724A of the carrier 724. The patterned diffuser 722 can be oriented such that the second side 724B of the carrier 724 and the diffuser layer 752 face a plurality of light sources 620A - 620C (see Figure 6 ), and such that the first side 724A of the carrier 724 and the reflector 726 face away from the plurality of light sources 620A - 620C. In another embodiment, the diffuser layer 752 can be positioned between the first side 724A of the carrier 724 and the reflector 726.

[0116] Figure 7B The patterned diffuser 722' includes a carrier 724' that defines a first side 724A' and a second side 724B'. The patterned diffuser 722' is generally similar to other patterned diffusers described and shown in reference Figure 7A , but the position of the diffuser layer 752' of the patterned diffuser 722' is different. In some embodiments, the diffuser layer 752' is positioned at the first side 724A' of the carrier 724', and the diffuser layer 752' can be directly attached to the first side 724A' of the carrier 724'. The reflector 726' is positioned at the second side 724B' of the carrier 724', and the reflector 726' can operate similar to other reflectors described herein. The reflector 726' has a first main reflector portion 726A', a second main reflector portion 726B', and a third main reflector portion 726C'. The reflector 726' also includes a secondary reflector portion 725'. In some embodiments, the reflector 726' can be directly attached to the second side 724B' of the carrier 724'. The patterned diffuser 722' can be oriented such that the second side 724B' of the carrier 724' and the diffuser layer 752' face a plurality of light sources 620A - 620C (see Figure 6 ), and such that the first side 724A' of the carrier 724' and the reflector 726' face away from the plurality of light sources 620A - 620C. In another embodiment, the diffuser layer 752' can be arranged between the second side 724B' of the carrier 724' and the reflector 726'. Although Figure 7A and Figure 7BTwo different orientations of the patterned diffusers 722, 722' are shown, but in other embodiments, the patterned diffusers 722, 722' may be positioned differently.

[0117] The diffuser layers 752, 752' can improve the lateral diffusion of light emitted from the light sources 620A - 620C, thereby improving light uniformity. The diffuser layers 752, 752' can have specular and diffuse reflectivities and specular and diffuse transmittances. The specular reflectivity or transmittance is the percentage of reflected or transmitted light along the specular direction, set to 0 or 8 degrees depending on the measurement, while the diffuse reflectivity or transmittance is the percentage of reflected or transmitted light excluding the specular reflectivity or transmittance. For example, the diffuser layers 752, 752' can have haze and transmittance. The diffuser layers 752, 752' can have a haze of about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 99% or greater, and a transmittance of about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95% or greater. In a particular illustrative embodiment, the diffuser layers 752, 752' can have a haze of about 70% and a total transmittance of about 90%. In other embodiments, the diffuser layers 752, 752' can have a haze of about 88% and a total transmittance of about 96%. In other embodiments, the diffuser layers 752, 752' can have a haze of about 99% and a total transmittance of about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90%. According to the American Society for Testing and Materials (ASTM) D1003 "Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics", haze is defined as the percentage of scattered transmitted light such that its direction deviates from the direction of the incident light beam by more than 2.5 degrees, and transmittance is defined as the percentage of transmitted light. Haze and transmittance are measured by various hazemeters.

[0118] The diffuser layers 752, 752' diffuse the light rays from the light sources 620A - 620C (see Figure 6 ). Thus, a backlight having the patterned diffusers 722, 722' including the diffuser layers 752, 752' may be thinner than a backlight having a patterned diffuser without the diffuser layers 752, 752'. Even with a thinner backlight, the backlight can still effectively hide the light sources 620A - 620C. The diffuser layers 752, 752' also diffuse light rays that would otherwise undergo total internal reflection. In addition, the diffuser layers 752, 752' can diffuse any light rays reflected back by the color conversion layer 230 (see Figure 2A ) or the diffuser sheet 228 (see Figure 2A ). Thus, the diffuser layers 752, 752' can increase the light by the color conversion layer 230 or the diffuser sheet 228 and any prism films 232 adjacent to the diffuser sheet 228 (see Figure 2A)(such as one or two brightness enhancement films) causes a light recycling effect.

[0119] In certain exemplary embodiments, the diffuser layers 752, 752' may include a uniform or continuous layer of scattering particles. The diffuser layers 752, 752' may include a uniform layer of scattering particles, where the distance between adjacent scattering particles is less than one-fifth of the light source width E (see Figure 5A ). Regardless of the position of the diffuser layers 752, 752' relative to the light source, the diffuser layers 752, 752' may exhibit similar diffusing characteristics. For example, the scattering particles may be in a transparent or white ink that includes micron-sized or nano-sized scattering particles, such as alumina particles, titanium dioxide (TiO2) particles, PMMA particles, or other suitable particles. The average particle diameter may vary, for example, in the range of about 0.1 micron to about 10.0 microns. In other embodiments, the diffuser layers 752, 752' may include an anti-glare pattern. The anti-glare pattern may be formed by a layer of polymer beads or may be etched. In this embodiment, the diffuser layers 752, 752' may have a thickness of, for example, about 1, 3, 7, 14, 21, 28, or 50 microns, or may have another suitable thickness.

[0120] In certain exemplary embodiments, the diffuser layers 752, 752' may include a pattern applied to the carrier 724 via screen printing. The diffuser layers 752, 752' may include screen printing on a primer layer (e.g., an adhesive layer) applied to the carrier 724. In other embodiments, the diffuser layers 752, 752' may be applied to the carrier 724 by laminating the diffuser layer to the carrier via an adhesive layer. In other embodiments, the diffuser layers 752, 752' may be applied to the carriers 724, 724' by embossing (e.g., hot embossing or mechanical embossing) the diffuser layers 752, 752' into the carriers 724, 724', stamping (e.g., roll stamping) the diffuser layers 752, 752' into the carriers 724, 724', or injection molding the diffuser layers 752, 752'. In other embodiments, the diffuser layers 752, 752' may be applied to the carriers 724, 724' by etching (e.g., chemical etching) the carriers 724, 724'. In some embodiments, the diffuser layers 752, 752' may be applied to the carriers 724, 724' using a laser (e.g., laser ablation).

[0121] In other embodiments, the diffuser layers 752, 752' can include a plurality of hollow microspheres. The hollow microspheres can be plastic hollow microspheres or glass hollow microspheres. For example, the hollow microspheres can be glass bubbles commercially available from 3M Company under the trade name "3M GLASS BUBBLES iM30K". The glass composition of these glass bubbles includes from about 70 to about 80 weight percent silica (SiO2), from about 8 to about 15 weight percent alkaline earth metal oxides, from about 3 to about 8 weight percent alkali metal oxides, and from about 2 to about 6 weight percent boron trioxide (B2O3), where each weight percentage is based on the total weight of the glass bubbles. In certain exemplary embodiments, the size (e.g., diameter) of the hollow microspheres can vary, e.g., from about 8.6 microns to about 23.6 microns, with a median size of about 15.3 microns. In another embodiment, the size of the hollow microspheres can vary, e.g., from about 30 microns to about 115 microns, with a median size of about 65 microns. In other embodiments, the diffuser layers 752, 752' can include a plurality of nanoscale color conversion particles, such as red and / or green quantum dots or other suitable phosphor particles. In other embodiments, the diffuser layers 752, 752' can include a plurality of hollow microspheres, nanoscale scattering particles, and nanoscale color conversion particles, such as red and / or green quantum dots or other suitable phosphor particles, such as potassium fluorosilicate (PFS)-based phosphors.

[0122] The hollow microspheres can first be uniformly mixed with a solvent (e.g., methyl ethyl ketone (MEK)), then mixed with any suitable binder (e.g., methyl methacrylate and silica), and then fixed by thermal curing or ultraviolet (UV) curing as needed to form a paste. The paste can then be deposited onto the surface of the carriers 724, 724' by slot coating, screen printing, or any other suitable means to form the diffuser layers 752, 752'. In this embodiment, the diffuser layers 752, 752' can have a thickness, for example, between about 10 microns and about 100 microns. In another example, the diffuser layers 752, 752' can have a thickness between about 100 microns and about 300 microns. If desired, multiple coatings can be used to form a thick diffuser layer. In each example, the haze of the diffuser layers 752, 752' can be greater than 99%, as measured by a haze meter such as BYK-Gardner's Haze-Gard. The advantages of using hollow microspheres within the diffuser layers 752, 752' can include reducing the weight of the diffuser layers 752, 752' and achieving a desired haze level at a small thickness.

[0123] Figure 8A-8BIt is a cross-sectional view of other exemplary patterned diffusers 822, 822'. The patterned diffusers 822, 822' are similar to other patterned diffusers described and shown herein, except that the patterned diffusers 822, 822' include encapsulation layers 854, 854'. The encapsulation layers 854, 854' may include a transparent resin material, silicone, or another suitable material. The transparent resin material, silicone, or another suitable material may have a transmittance of more than about 60%, and preferably more than about 90%. The encapsulation layer 854 may include nano-scale or micro-scale scattering particles.

[0124] In Figure 8A it, the carrier 824 defines a first side 824A and a second side 824B. The reflector 826 is positioned adjacent to the second side 824B. The reflector 826 has a first main reflector portion 826A, a second main reflector portion 826B, and a third main reflector portion 826C. The reflector 826 also has a secondary reflector portion 825. Additionally, the encapsulation layer 854 is positioned adjacent to the second side 824B of the carrier 824 and encapsulates some or all of the portions of the reflector 826. Figure 8A The patterned diffuser 822 of Figure 6 is configured to be arranged such that the second side 824B of the carrier 824 faces a plurality of light sources 620A - 620C within the backlight (see

[0125] In Figure 8B it, the carrier 824' defines a first side 824A' and a second side 824B'. The reflector 826' is positioned adjacent to the first side 824A'. The reflector 826' includes a first main reflector portion 826A', a second main reflector portion 826B', and a third main reflector portion 826C'. The reflector 826 also includes a secondary reflector portion 825'. The encapsulation layer 854' is positioned adjacent to the first side 824A' of the carrier 824' and encapsulates some or all of the portions of the reflector 826'. Figure 8B The patterned diffuser 822' of Figure 6 is configured to be arranged such that the first side 824A' of the carrier 824' faces away from a plurality of light sources 620A - 620C within the backlight (see

[0126] Figure 9A-9B It is a cross-sectional view of other exemplary patterned diffusers 922, 922'. The patterned diffusers 922, 922' are generally similar to other diffusers described and shown herein. However, the patterned diffusers 922, 922' include reflectors on both sides.

[0127] InFigure 9A In this case, the patterned diffuser 922 includes a carrier 924 that defines a first side 924A and a second side 924B. A first reflector 926 is positioned at the first side 924A of the carrier 924. The first reflector 926 includes a first main reflector portion 926A, a second main reflector portion 926B, and a third main reflector portion 926C. The first reflector 926 also includes a first secondary reflector portion 925A. Additionally, a second reflector 926AA is positioned at the second side 924B of the carrier 924. The second reflector 926AA includes a fourth main reflector portion 926D, a fifth main reflector portion 926E, and a sixth main reflector portion 926F. The second reflector 926AA also includes a second secondary reflector portion 925B. The first reflector 926 is configured to be aligned with light sources 620A - 620C (see Figure 6 ) within the backlight, where each main reflector portion 926A - 926F is configured to be aligned with a corresponding light source among the light sources 620A - 620C (see Figure 6 ). The patterned diffuser 922 can be arranged such that either the first side 924A or the second side 924B of the carrier 924 faces the light sources 620A - 620C within the backlight. The reflectors 926, 926AA may or may not have the same geometry.

[0128] Figure 9B is a cross - sectional view of another exemplary patterned diffuser 922'. The patterned diffuser 922' is similar to the patterned diffuser 922 described and shown in reference Figure 9A . However, the patterned diffuser 922' includes encapsulation layers 954A and 954B. In Figure 9B , the patterned diffuser 922' includes a carrier 924' that defines a first side 924A' and a second side 924B'. A first reflector 926' is positioned at the first side 924A' of the carrier 924'. The first reflector 926' has a first main reflector portion 926A', a second main reflector portion 926B', and a third main reflector portion 926C'. The first reflector 926' also includes a first secondary reflector portion 925A'. A second reflector 926AA' is positioned at the second side 924B' of the carrier 924'. The second reflector 926AA' includes a fourth main reflector portion 926D', a fifth main reflector portion 926E', and a sixth main reflector portion 926F'. The second reflector 926AA' also includes a second secondary reflector portion 925B'.

[0129] The encapsulation layer 954A is positioned adjacent to the first side 924A' of the carrier 924 and encapsulates at least a portion of the first reflector 926'. The encapsulation layer 954B is positioned adjacent to the second side 924B' of the carrier 924 and encapsulates at least a portion of the second reflector 926AA'. Each of the encapsulation layers 954A and 954B may include a transparent resin material, silicone, or another suitable material. The patterned diffuser 922' may be arranged such that the first side 924A' or the second side 924B' of the carrier 924 faces the light sources 620A - 620C within the backlight (see Figure 6 ).

[0130] The various embodiments discussed herein help to concentrate more light within a smaller angular range, and this is shown in Figure 10 and Figure 11 . Figure 10 is a graph showing curves 1072 and 1070, where curve 1072 represents the luminance emitted at various angles from a backlight of a patterned diffuser using a patterned diffuser similar to Figure 3A , and curve 1070 represents the luminance emitted at various angles from a backlight using a 2.2 - millimeter diffuser plate. Additionally, Figure 11 has a graph showing curves 1174 and 1176, where curve 1174 represents the normalized angular luminance at various angles for a backlight of a patterned diffuser using a patterned diffuser similar to Figure 2A , and curve 1176 represents the normalized angular luminance at various angles for a backlight using a 2.2 - millimeter diffuser plate.

[0131] Figure 10 and Figure 11 show that Figure 2A 's patterned diffuser 222 results in a narrower angular luminance relative to the 2.2 - millimeter diffuser plate, where more light is concentrated along the axis direction close to the zero - degree mark. The FWHM of the patterned diffuser is approximately 13.4 degrees, and the FWHM of the 2.2 - millimeter diffuser plate is approximately 136 degrees. Additionally, as shown in Figure 10As shown, curve 1072 has a maximum brightness of approximately 1,200,000 nits at approximately 0 degrees, and curve 1070 has a maximum brightness of less than 100,000 nits at approximately 0 degrees. Even at other angles, curve 1072 has increased brightness values relative to curve 1070. At all angles between approximately -60 degrees and 60 degrees, curve 1072 has higher brightness values relative to curve 1070. Narrow angle performance can be an advantage in various applications, particularly for head-up displays where the light must be suitable for a narrow angle range. Notably, even though a similar amount of power is used in the backlights for curves 1070, 1072, the area under curve 1072 is significantly larger than the area under curve 1070, indicating that more light is wasted in the case of using a 2.2 mm diffuser plate.

[0132] As Figure 11 shown, curve 1176 has a circular shape, where the brightness gradually increases as the angle increases from -80 degrees to 0 degrees, and the brightness gradually decreases as the angle increases from 0 degrees to 80 degrees. At -80 degrees, the normalized brightness of curve 1176 is approximately 0.2. At -60 degrees, the normalized brightness of curve 1176 is approximately 0.65. At -40 degrees, the normalized brightness of curve 1176 is approximately 0.85. At -20 degrees, the normalized brightness of curve 1176 is approximately 0.95. At 0 degrees, the normalized brightness of curve 1176 is approximately 1. At 20 degrees, the normalized brightness of curve 1176 is approximately 0.95. At 40 degrees, the normalized brightness of curve 1176 is approximately 0.85. At 60 degrees, the normalized brightness of curve 1176 is approximately 0.65. At 80 degrees, the normalized brightness of curve 1176 is approximately 0.2.

[0133] In contrast, as the angle increases from -20 degrees to 0 degrees, curve 1174 increases rapidly, and as the angle increases from 0 degrees to 20 degrees, curve 1174 decreases rapidly. At -80 degrees, the normalized brightness of curve 1174 is approximately 0. At -60 degrees, the normalized brightness of curve 1174 is approximately 0.05. At -40 degrees, the normalized brightness of curve 1174 is approximately 0.1. At -20 degrees, the normalized brightness of curve 1174 is approximately 0.167. At 0 degrees, the normalized brightness of curve 1174 is approximately 1. At 20 degrees, the normalized brightness of curve 1174 is approximately 0.167. At 40 degrees, the normalized brightness of curve 1174 is approximately 0.1. At 60 degrees, the normalized brightness of curve 1174 is approximately 0.05. At 80 degrees, the normalized brightness of curve 1174 is approximately 0.

[0134] Figure 12 is a graph of curve 1278 showing the brightness obtained at various angles, where a similar Figure 2Aa display system of display system 238, and wherein the brightness is measured before light from light sources 220A - 220C propagates through the patterned diffuser 222 of the display system. As shown, curve 1278 has a relatively small brightness at zero degrees and larger brightness at other angles. At -80 degrees, curve 1278 has a brightness of approximately 50,000 nits. At -60 degrees, curve 1278 increases significantly to a brightness of approximately 1,200,000 nits. At -40 degrees, curve 1278 decreases to a brightness of approximately 950,000 nits. At -20 degrees, curve 1278 decreases to a brightness of approximately 450,000 nits. At 0 degrees, curve 1278 decreases to a brightness of approximately 250,000 nits. At 20 degrees, curve 1278 remains at a brightness of approximately 250,000 nits. At 40 degrees, curve 1278 increases to a brightness of approximately 400,000 nits. At 60 degrees, curve 1278 increases to a brightness of approximately 750,000 nits. At 80 degrees, curve 1278 decreases to a brightness of approximately 50,000 nits.

[0135] Figure 13 is a graph showing an example of how the FWHM can be calculated. In Figure 13 the curve has a Gaussian distribution, but in other embodiments the curve can have other shapes. The curve defines a Y MAX value and a Y MAX / 2 value (the value is half of the Y MAX value). The curve can have at least two coordinates on the x-axis, where the curve has a Y MAX / 2 value, including a first x coordinate X1 and a second x coordinate X2, where the second x coordinate X2 is greater than the first x coordinate X1. The FWHM is the difference between the second x coordinate X2 and the first x coordinate X1.

[0136] Figure 14 is a flowchart showing an exemplary method 1400 for manufacturing a display system. In operation 1402, a substrate is provided. In operation 1404, one or more light sources are positioned close to the substrate. In some embodiments, the light sources can be positioned such that they are in contact with the surface of the substrate. In operation 1406 a first reflective layer is positioned close to the substrate. In some embodiments, the first reflective layer can be positioned such that it is in contact with the surface of the substrate.

[0137] At operation 1408, the patterned diffuser is positioned proximate to the light source. The patterned diffuser includes at least one reflector, and each of these reflectors is positioned such that they are properly aligned with one or more light sources. In some embodiments, the reflectors have a main reflector portion that has an increased thickness relative to other portions of the reflector, and the main reflector portions can each be positioned such that they are properly aligned with the light sources. The patterned diffuser can also include a carrier having a first side and a second side opposite the first side, and the reflectors can be positioned on the first side of the carrier. However, in some embodiments, the reflectors can be positioned on the second side of the carrier. The reflectors also have a minimum thickness and a maximum thickness greater than the minimum thickness. In some embodiments, the minimum thickness of the reflector can be at least about 13% of the maximum thickness of the reflector, and the minimum thickness of the reflector can be at most about 90% of the maximum thickness of the reflector. In some embodiments, the patterned diffuser can be positioned between the prism film and the panel. In some embodiments, a patterned diffuser without any volume diffuser components can be provided at the second side of the carrier, but in other embodiments, a volume diffuser component having a uniform diffused pattern or some other pattern can be provided at the second side of the carrier. Additionally or alternatively, the patterned diffuser can be provided with an anti-reflection coating on the first side and / or the second side of the carrier, and the anti-reflection coating can include a single layer or multiple layers of coating.

[0138] In some embodiments, the reflector can define a minimum ink density and a maximum ink density, and the minimum ink density of the reflector can be at least about 13% of the maximum ink density of the reflector. However, in some embodiments, the minimum ink density of the reflector can be at least about 40% of the maximum ink density of the reflector, and in some embodiments, the minimum ink density of the reflector can be between about 75% and about 90% of the maximum ink density of the reflector.

[0139] The substrate, the light source, the first reflective layer, and the patterned diffuser form at least a portion of the backlight, and the backlight can also include other components. The light output from the backlight has an angular distribution defined by the full width at half maximum, and in some embodiments, this full width at half maximum can be less than about 116 degrees. However, in other embodiments, the full width at half maximum can be less than about 50 degrees, less than about 25 degrees, less than about 15 degrees, or even less than about 13.4 degrees.

[0140] In operation 1410, the panel is positioned proximate the backlight, and the panel can be positioned such that the panel is configured to receive light that has been output from the backlight. In some embodiments, the panel can be a liquid crystal panel. In some embodiments, a diffuser sheet can be disposed along the panel. The diffuser sheet can include at least two diffusing portions, including a first diffusing portion and a second diffusing portion. The first diffusing portion and the second diffusing portion can be positioned relative to each other such that a light beam from a light source is configured to propagate through both the first diffusing portion and the second diffusing portion. In some embodiments, the diffuser sheet can be positioned between a patterned diffuser and the light source. In some embodiments, a color conversion layer, a diffuser sheet, a prism film, and a reflective polarizer can be disposed along the panel.

[0141] In operation 1412, the optical element is positioned proximate the panel. The optical element can collect light within a predetermined angle after the light has been output from the backlight and passed through the panel, and in some embodiments, the predetermined angle can be less than about 20 degrees.

[0142] Summary

[0143] Benefiting from the foregoing description and the teachings presented in the associated drawings, those skilled in the art of these embodiments will envision many modifications and other embodiments of the present disclosure. Accordingly, it is to be understood that the embodiments are not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the present disclosure. Additionally, although the foregoing description and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and / or functions, it is to be understood that alternative embodiments may provide different combinations of elements and / or functions without departing from the scope of the present disclosure. In this regard, for example, combinations of elements and / or functions different from those explicitly described above are also contemplated within the scope of the present disclosure. Although specific terms are employed herein, they are used in a general and descriptive sense only and not for purposes of limitation.

Claims

1. A display system, characterized in that, The display system includes: an optical element; a panel; and a backlight, the backlight including: a substrate; at least one light source proximate to the substrate; a first reflective layer on the substrate; and a patterned diffuser, the patterned diffuser including at least one reflector positioned proximate to the at least one light source, each of the at least one reflectors being aligned with one or more corresponding light sources of the at least one light source, the at least one reflector having a minimum thickness and a maximum thickness greater than the minimum thickness, wherein light output from the backlight has an angular distribution defined by a full width at half maximum, wherein the full width at half maximum is less than 116 degrees, wherein the optical element collects the light within a predetermined angle after the light is output from the backlight and passes through the panel, and wherein the predetermined angle is less than 20 degrees.

2. The display system according to claim 1, wherein The full width at half maximum is less than 50 degrees.

3. The display system according to claim 1, wherein The full width at half maximum is less than 25 degrees.

4. The display system according to claim 1, wherein, The full width at half maximum is less than 13.4 degrees.

5. The display system according to any one of claims 1-4, characterized in that, The panel is a liquid crystal panel.

6. The display system according to any one of claims 1-4, characterized in that, The display system further includes a color conversion layer.

7. The display system according to any one of claims 1-4, characterized in that, The display system further includes a diffuser sheet.

8. The display system according to claim 7, wherein The diffuser sheet includes at least two diffusing portions, including a first diffusing portion and a second diffusing portion, and wherein a light beam from the at least one light source is configured to propagate through both the first diffusing portion and the second diffusing portion.

9. The display system according to claim 8, characterized in that, The diffuser sheet is positioned between the patterned diffuser and the at least one light source.

10. The display system according to any one of claims 1-4, characterized in that, The display system further includes a prism film.

11. The display system according to claim 10, wherein, The patterned diffuser is positioned between the prism film and the panel.

12. The display system according to any one of claims 1-4, characterized in that, The display system further includes a reflective polarizer.

13. The display system according to any one of claims 1-4, characterized in that, The minimum thickness of the at least one reflector is at least 13% of the maximum thickness of the at least one reflector, and wherein the minimum thickness of the at least one reflector is at most 90% of the maximum thickness of the at least one reflector.

14. The display system according to any one of claims 1-4, characterized in that, The patterned diffuser includes a carrier, wherein the carrier has a first side and a second side opposite the first side, wherein the first side faces away from the at least one light source, and wherein the at least one reflector is positioned on the first side of the carrier.

15. The display system according to claim 14, wherein The carrier does not have any volume diffusing components positioned on the second side of the carrier.

16. The display system according to claim 14, wherein The carrier defines a uniform diffusing pattern on the second side of the carrier.

17. The display system according to any one of claims 1-4, characterized in that, The at least one reflector defines a minimum ink density and a maximum ink density, and wherein the minimum ink density of the at least one reflector is at least 13% of the maximum ink density of the at least one reflector.

18. The display system according to claim 17, wherein The minimum ink density of the at least one reflector is at least 40% of the maximum ink density of the at least one reflector.

19. The display system according to claim 18, wherein, The minimum ink density of the at least one reflector is between 75% and 90% of the maximum ink density of the at least one reflector.

20. A backlight, characterized in that, including: a substrate; at least one light source, the at least one light source being proximate to the substrate; a first reflective layer, the first reflective layer being on the substrate; and A patterned diffuser, the patterned diffuser including at least one reflector positioned proximate to the at least one light source, each of the at least one reflectors being aligned with one or more corresponding light sources of the at least one light source, the at least one reflector having a minimum thickness and a maximum thickness greater than the minimum thickness, wherein light output from the backlight has an angular distribution defined by a full width at half maximum, wherein the full width at half maximum is less than 116 degrees, wherein an optical element collects the light within a predetermined angle after the light is output from the backlight and passes through the panel, and wherein the predetermined angle is less than 20 degrees.

21. The backlight according to claim 20, wherein The full width at half maximum is less than 25 degrees.

22. The backlight according to claim 21, wherein The full width at half maximum is less than 15 degrees.

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