Polarizing edge-coupled light in backlight

Abstract

A backlight device includes a light emitting element configured to emit visible light and a polarization device including a prism, the prism being positioned to receive the visible light and polarize the visible light to produce polarized light. The backlight device further includes a light guide panel configured to receive the polarized light at an input surface facing the polarization device and distribute the polarized light to a main surface of the light guide panel facing a display screen.

Description

[0001] Priority application

[0002] This application claims the benefit of priority to U.S. Patent Application Serial No. 16 / 721,637, filed on December 19, 2019, and entitled “POLARIZING EDGE COUPLEDLIGHT IN BACKLIGHT,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a display device with improved brightness and display power efficiency. The improved backlight includes a polarization device configured to increase the polarization of light incident on a light guide. The increased polarization provides improved power efficiency and brightness. Background Art

[0004] Displays, especially three-dimensional (3D) holographic displays, suffer from low brightness and low power efficiency. Embodiments herein provide improved brightness and power efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] According to some embodiments, the figures show various views of a device including a lens that can shape light emitted from one or more light emitting diodes (LEDs). In the views presented herein, it is assumed that the light is emitted from the front of the lens so that one or more LEDs can be positioned toward the back of the lens. The terms "front", "rear", "top", "bottom", and "side" should be understood as relative to each other, where "front" and "rear" are opposite to each other, "top" and "bottom" are opposite to each other, and "side" is between "top" and "bottom". Other directional terms are used merely for convenience in describing lenses and other elements and should not be interpreted as limiting in any way.

[0006] Figure 1 A schematic diagram of an embodiment of a backlight unit is shown by way of example, the backlight unit comprising a planar light guide arranged on top of a protection plate and a light emitting element arranged on one side of the light guide.

[0007] Figure 2 By way of example, a schematic diagram of an embodiment of another backlight unit is shown, which comprises a planar light guide arranged on a protection plate.

[0008] Figure 3 A partial cross-sectional schematic diagram of an embodiment of a display device including a backlight is shown by way of example.

[0009] Figure 4 A schematic diagram of one embodiment of a display device providing s-polarized light to a screen is shown by way of example.

[0010] Figure 5 A schematic diagram of another embodiment of a display device providing s-polarized light to a screen is shown by way of example.

[0011] Figure 6 By way of example, it is shown that Figure 5 The angle of view indicated by the arrow marked “6” Figure 5 A perspective view of a portion of a display device.

[0012] Figure 7 A schematic diagram of one embodiment of a display device providing p-polarized light to a screen is shown by way of example.

[0013] Figure 8 A schematic diagram of another embodiment of a display device providing p-polarized light to a screen is shown by way of example.

[0014] Fig. 9 A flow chart illustrating an example of a method for forming a light emitting device according to some examples is shown.

[0015] Fig.10 A logical block diagram of an extended reality (XR) (eg, augmented reality (AR) / virtual reality (VR) / mixed reality (MR)) system is shown by way of example.

[0016] Throughout the several views, corresponding reference numerals indicate corresponding parts. The elements in the drawings are not necessarily drawn to scale. The configurations shown in the drawings are merely examples and should not be construed as limiting the scope of the disclosed subject matter in any way. DETAILED DESCRIPTION

[0017] Figure 1 A schematic diagram of an embodiment of a backlight unit 10 is shown by way of example, and the backlight unit 10 includes a planar light guide 20 disposed on a protective plate 12 and a light emitting element 130 disposed on one side of the light guide 20. Some of the light 50 entering the light guide 20 from the light emitting element 130 is reflected toward the top surface 152 of the light guide 20 by the patterned bottom surface 22 and another optional reflective sheet located between the light guide 20 and the back plate 12, and is emitted from the light guide 20. The emitted light 54 provides backlight to a display 140 (e.g., a liquid crystal display (LCD)) on the side of the light guide 20 opposite to the reflective sheet 42. The reflective sheet 42 is separated from the bottom surface 22 by an air gap 44. The reflective sheet 42 may include a polarization maintaining surface, such as a reflector. The reflective sheet 42 may include a scattering surface (e.g., a white painted surface). For example, the pattern may be printed or molded on the surface 22.

[0018] Figure 2By way of example, a schematic diagram of an embodiment of a backlight unit 21 is shown, which backlight unit 21 includes a planar light guide 60 arranged on a protective plate 12. The planar light guide 60 is similar to Figure 1 The light guide 20 has a patterned top surface 152 instead of a patterned bottom surface 22.

[0019] In some embodiments, the light emitting element 130 may be a rectangular single line array or a multi-line array. In other embodiments, the light emitting element 130 may be formed or otherwise manufactured into a shape that approximates a non-rectangular shape (e.g., a circle or an ellipse). Light emitting elements such as light emitting diodes (LEDs) may be monochromatic or polychromatic, or in some embodiments, red, green, and blue (RGB) arrays. Pixels of different colors may be staggered, or in other embodiments, pixels of different colors may have other groupings, in which groups of one color are arranged together in one or two orthogonal directions. In other embodiments, at least some of the light emitting element sets may provide light of different wavelengths for color adjustment. For example, one light emitting element set may provide white light, while another light emitting element set may provide red light. The light emitting element may be formed of II-VI, III-V, or other compound semiconductors, which may be binary, ternary, quaternary, or other compounds. For example, gallium nitride (GaN) is used for blue LEDs, gallium arsenide (GaAs) is used for infrared (IR) LEDs, and indium gallium phosphide (InGaP), indium gallium aluminum phosphide (InGaAlP), or indium gallium arsenic phosphide (InGaAsP) is used for visible light LEDs, and so on. Alternatively, a wavelength conversion structure can be disposed in the path of light extracted from the LED. The wavelength conversion structure includes one or more wavelength conversion materials, which can be, for example, conventional phosphors, organic phosphors, quantum dots, organic semiconductors, II-VI or III-V semiconductors, II-VI or III-V semiconductor quantum dots or nanocrystals, dyes, polymers, or other luminescent materials. The wavelength conversion material includes a light scattering or light diffusing element (such as titanium dioxide (TiO2)) that absorbs light emitted by the LED and emits one or more different wavelengths of light. The light provided by the light source can be white, polychromatic, or monochromatic.

[0020] Figure 3 A partial cross-sectional schematic diagram of an embodiment of a display device 300 including a backlight is shown by way of example. The display device 300 includes a display screen 140, a light guide 120, and a light emitting element 130. According to one embodiment, the display screen 140 may include an LCD screen. The LCD screen may be part of a television, a computer monitor, a smartphone screen, a watch screen, a calculator screen, or other screens.

[0021] The light emitting element 130 may transmit light toward the light guide 120. The light emitting element 130 may include a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), etc. Theoretically, the light emitting element 130 may generate light having a Lambertian distribution or a near-Lambertian distribution. The light emitting element 130 may include a top coating 212 and a side coating.

[0022] The display device 300 further includes a backplane 202, reflector sheets 204, 206, and a substrate 214. The backplane 202 provides protection from the external environment for the reflector sheets 204, 206, the light emitting elements 130, the substrate 214, the light guide 120, and the surface of the display screen 140 facing the light guide 120. The backplane 202 can be made of metal, ceramic, polymer, etc. The extent of the backplane 202 extending above the top surface 152 of the light guide 120 is sometimes referred to as a bezel.

[0023] The reflector sheets 204, 206 are made of light scattering and highly reflective materials. The reflective material can reflect 90%, 95%, 99%, more or less of the light incident on it, or some value therebetween. The reflector sheets 204, 206 can be patterned to help scatter light or reflect light to a specific location.

[0024] The top coating 212 can change the color of the light emitted from the light emitting element 130. For example, if the top coating 212 is a phosphor, the light emitted from the light emitting element 130 will appear whiter to the human eye. This is because the phosphor absorbs some of the blue light emitted from the light emitting element 130.

[0025] The side coating 210 can be made of a broadly scattering, highly reflective material (e.g., reflectivity greater than 80%, 85%, 90%, 95%, 99%, or some percentage therebetween at the wavelength of the light emitting element 130). The side coating 210 can help ensure that more light is transmitted through the top coating 212 or toward the light guide 120. Examples of side coating materials include filled silicone, acrylic, white plastic, or other dielectric coatings.

[0026] Substrate 214 provides power and circuit wiring for light emitting element 130. Light emitting element 130 can be electrically and mechanically connected to an electrical power source through traces or other electrical interconnections on or in substrate 214. Substrate 214 can include a flexible or rigid printed circuit board (PCB). Flexible PCBs can be made of polyimide, polydimethylsiloxane, etc. Rigid PCBs can be made of FR-4, prepreg, etc.

[0027] The light guide 120 is designed to spread the light from the light emitting element 130 as evenly as possible across the display screen 140. The light transmission on the display screen 140 depends on the polarization of the incident light. The display screen transmission is maximum for a specific polarization. In addition, the emerging LGP with diffraction pattern requires polarized light for optimal performance. Example embodiments provide a solution to control the polarization of light incident on the display screen 140.

[0028] Polarization is defined relative to the plane of incidence. The plane of incidence is the plane containing the incident and reflected rays and the normal to the sample surface. Perpendicular (s-) polarization is polarization where the electric field is perpendicular to the plane of incidence, while parallel (p-) polarization is polarization where the electric field is parallel to the plane of incidence.

[0029] Different light polarizations can also be absorbed to different degrees by different materials. This is an important property of an LCD screen (e.g., display screen 140). It is beneficial to have as little light as possible absorbed by the material of the LCD screen. This can be limited by polarizing the light that is incident on the light guide panel (e.g., light guide 120) and ultimately on the LCD screen.

[0030] Incandescent lamps, fluorescent lamps, LEDs, and many other light sources are randomly polarized. LCD screens have two (or more) layers of polarizing material stacked on top of each other. Typically, both layers are polarized in the same way so that light passes through both layers. One (or both) of the layers can be made of liquid crystal. The polarization of the liquid crystal changes based on an applied voltage. When a voltage is applied, the polarization of the crystal can shift so that it is 90 degrees different from what it was before the voltage was applied. This creates areas that do not allow light to pass through them. Different areas of the liquid crystal can be controlled by voltages from a control circuit.

[0031] Liquid crystals are typically thin rod-shaped molecules that move in response to an applied voltage. In a display, there are many liquid crystals, and typically not all have exactly the same orientation relative to one another, but they typically point in more or less the same direction. Liquid crystals turn and move in response to a voltage, such as to be in another orientation.

[0032] According to some embodiments, based on the direction the liquid crystal is pointing, the polarization of the incident light is either (a) rotated 90 degrees when passing through the liquid crystal, or (b) not rotated at all, compared to the polarization of the incident light and the thickness of the liquid crystal. One can take advantage of this polarization rotation by using a polarizer. Placing a polarizer on the output of the liquid crystal allows light to pass through only when the polarization of the light matches the polarization orientation of the polarizer. For example, turning on the voltage causes the liquid crystal to rotate one way, and light is allowed to pass through. Turning off the voltage prevents the light from passing through, or vice versa.

[0033] Color is provided by placing liquid crystal molecules into a pixel format and placing colored (e.g., red, green, blue, or a combination thereof) filters over them. Some LCDs, such as basic digital watches, have no "backlight" and no color filters, and therefore only produce black and gray backgrounds. These watches rely on ambient light to pass through the liquid crystals. However, many LCD displays have a backlight. The backlight helps provide vivid color combinations (by allowing the RGB filters to transmit a large amount of light) and high brightness levels.

[0034] To improve the efficiency of LCD backlights, polarized light may be beneficial. As previously discussed, polarized light may have better reflective properties and may be less absorbed by materials in the LCD screen. For at least these reasons, it is desirable to control the polarization of light incident on the LGP, and ultimately the LCD screen.

[0035] However, simply adding a polarizer between the LED and the LGP increases the bezel length of the display. Also, for thermal management, it is beneficial to mount the LED on a separate PCB from the polarizer.

[0036] Example embodiments include new designs for edge coupling and polarization of emission (e.g., Lambertian emission) from the light emitting element 130 to the light guide 120. Example embodiments may include a modified version of a polarizing beam splitter (PBS). The design of example embodiments is compact and may reduce the frame length (compared to other polarization solutions) by folding the LED coupling path. In addition, example embodiments may simplify thermal management of the LEDs because they may be mounted on larger circuit boards. The circuit board may be oriented so that the major surface (the surface on which the light emitting element 130 is mounted) faces the screen 140. This orientation is approximately 90 degrees to the normal orientation of the light emitting element 130.

[0037] 3D displays based on light field technology rely on diffraction from a diffractive optical element (DOE) pattern on the top surface 152 of the light guide 120. In many 3D displays, light is edge-coupled from and into the edge of the light guide 120. On top of the light guide 120, a liquid crystal panel (e.g., screen 140) modifies the spatial distribution of light by switching pixels on and off. The incident light on the liquid crystal panel and inside the light guide 120 can be polarized to maximize the power efficiency of the display and the brightness of the light emitted by the screen 140.

[0038] Figure 4By way of example, a schematic diagram of an embodiment of a display device 400 that provides s-polarized light to a screen 140 is shown. The display device 400 shown includes a backplane 202, a reflector sheet 204, a substrate 214, a light emitting element 130, a side coating 210, a top coating 212, a polarizing device, and a display screen 140. The polarizing device includes prisms 320, 322, reflectors 316, 318, and a film 338.

[0039] The polarization device polarizes the unpolarized light 324 from the light emitting element 130. The light 324 is received through the receiving surface 342. The polarization device transmits the polarized light 334 toward the light guide 120 through the transmitting surface 340.

[0040] Light from the receiving surface 342 is incident on the prism 320. A prism (e.g., prisms 320, 322) is an optical element that is nearly transparent (at a specific wavelength) and refracts light. A prism generally has a polyhedral shape. The shape of a prism with a triangular base is called a triangular prism. A triangular prism includes sides that share an edge with a hypotenuse and are connected by the hypotenuse. The sides and the hypotenuse are generally planar, generally rectangular, and generally flat. The sides and the hypotenuse are connected by two generally parallel faces (referred to as bases).

[0041] The s-polarization from the non-polarized light 324 is reflected by the film 338 as polarized light 334 to the light guide 120. The remaining portion of the non-polarized light 324 is transmitted as light 328 having polarization p. The reflector 316 reflects the backlight 326 as light 336, which is partially reflected as polarization s as shown by light 326 and is mainly transmitted through the film 338, where polarization p is shown by light 332. Light 332 is scattered from the layer 212 and loses its polarization and is recycled as non-polarized light 324. Light 326 is reflected back as 326 and undergoes partial reflection as light 328 and partial transmission as polarized light 334. The film 338 can be made of polyester, epoxy, or urethane-based adhesives, combinations thereof, and the like. The film 338 can include a multilayer structure. The film 338 can include a layer of adhesive and alternating layers of high refractive index material and low refractive index material for polarization modification. Film 338 may use Brewster angles in each layer to separate orthogonal polarization components of light.

[0042] Light 326, 328 is reflected by mirrors 318, 316 as light 330, 336, respectively. Light 330, 336 is again incident on film 338, and a portion of light 330, 336 polarized in a particular manner is transmitted as light 334. Another portion of light 330, 336 is directed toward top coating 212.

[0043] Light 332 is recycled to the top coating 212 and randomized. The recycled light with randomized polarization is again incident on the prism 320 and acquires the proper polarization and is emitted through the transmissive surface 340 as light 334 that is mostly polarized (greater than 50%, 75%, 80%, 90%, 95%, 99%, greater, or some percentage therebetween).

[0044] The orientation of the substrate 214 and the light emitting elements 130 relative to the light guide 120 is different from the normal. Figure 4 1 shows a typical orientation between the light emitting element 130 and the light guide 120 according to an example embodiment. Typically, the light emitting element 130 transmits light directly toward the input surface 360 ​​of the light guide 120. However, in Figure 4 In the embodiment of FIG. 3 , the light emitting element 130 emits light substantially perpendicular to the input surface 360 ​​and the polarization device redirects the light 324 toward the input surface 360. In other words, in FIG. Figure 4 , light emitting element 102 is oriented to transmit light 324 toward display screen 140. Light 324 from light emitting element 130 is polarized by the polarization device and redirected to light guide 120.

[0045] Figure 4 The embodiments in not only provide polarized light, but also allow for improved thermal management of the light emitting element 130 and other components of the display device 300. The improved thermal management can come from increased space for heat sink components. The heat sink components can be on the substrate 214. The depth of the backplane 202 (indicated by arrow 344) is typically less than the width of the bezel in front of the display device 400 (indicated by arrow 346). By allowing the substrate 214 to substantially span the width of the bezel (indicated by arrow 346), a larger heat sink component can be used compared to the size of the heat sink component that at most spans the thickness of the backplane 202 (e.g., the dimension indicated by arrow 344). However, the improved thermal management of the display device 400 may result in the system being slightly thicker (e.g., corresponding to the dimension of arrow 344) than other polarizer solutions, such as Figure 4 as shown in .

[0046] Figure 5 A schematic diagram of an embodiment of a display device 500 with an improved backlight is shown by way of example. Display device 500 is similar to display device 400, wherein display device 500 includes a different polarization device 416. Similar to display device 400, polarization device 416 of display device 500 is configured to polarize light having s-polarization. Polarization device 416 will be discussed in more detail below.

[0047] Figure 6 By way of example, a schematic diagram of a portion of a display device 500 is shown, wherein a view of the polarization device 416 is shown by Figure 54. The illustrated polarization device 416 includes three prisms 540, 542, 544. Prism 540 is coupled to the hypotenuse of prism 542 on a first side. Prism 540 is coupled to the hypotenuse of prism 544 on a second side. The hypotenuse of prism 540 faces the input surface 360 ​​of light guide 120.

[0048] The polarization device 416 polarizes the unpolarized light 546 from the light emitting element 130. The light 546 is received through a receiving surface 560 of the polarization device 416. The polarization device 416 transmits the polarized light 550 toward the light guide 120 through a transmitting surface 562.

[0049] Light from receiving surface 560 is incident on prisms 540, 542, 544. Prisms 540, 542, 544 may include a birefringent crystal material.

[0050] A portion of polarized (s-polarized or p-polarized) light 550 is transmitted out of transmissive surface 562. Another portion of light 550 is incident on film 538 and is reflected to prisms 542, 544 as light 548. Film 538 may be an adhesive that connects prisms 540, 542, 544. Film 538 may be similar to film 338.

[0051] Light 548 is reflected by reflector 516 as light 552. Light 552 is again incident on film 538, and a portion of light 552 polarized in a particular manner is transmitted as light 550. Another portion of light 554 is directed toward top coating 212.

[0052] The light 554 is recycled to the top coating 212 and randomized. The recycled light with the randomized polarization is again incident on the prisms 542, 544 and acquires the proper polarization to be emitted out of the transmissive surface 562 as light 550 that is mostly polarized (more than 50%, 75%, 80%, 90%, 95%, 99%, greater, or some percentage therebetween).

[0053] Reflector 516 may surround prisms 540, 542, 544, leaving transmissive surface 562 and receiving surface 560 exposed. Reflector 516 may be similar to reflectors 316, 318. Compared to display device 400, display device 500 is a thinner device with a slightly increased bezel length.

[0054] Figure 7 By way of example, a schematic diagram of an embodiment of a display device 700 for providing p-polarized light to a screen 140 is shown. The display device 700 shown includes a backplane 202, reflector sheets 204, 206, a substrate 214, a light emitting element 130 (including Figure 7The polarizing device includes a side coating 210 and a top coating 212 not shown in the figure), a polarizing device and a display screen 140. The polarizing device includes prisms 620, 622, a reflector 616 and a film 638.

[0055] The polarization device polarizes the unpolarized light 624 from the light emitting element 130. The light 624 is received through the receiving surface 642. The polarization device emits p-polarized light 634 through the transmitting surface 640 towards the input surface 360 ​​of the light guide 120.

[0056] Light from receiving surface 642 is incident on prism 622. Prisms 620, 622 can be similar to the other prisms discussed. P-polarized light from unpolarized light 624 is transmitted by film 638 as p-polarized light 634 to light guide 120. Film 638 can be similar to the other films discussed. The remainder of unpolarized light 624 is transmitted as light 626, 636 having primarily s-polarization.

[0057] Light 626, 636 is reflected by mirror 616 as light 630, 628, respectively. Light 630, 628 is incident on film 638 again, and a portion of p-polarized light 630, 628 is transmitted as light 334. Another portion of light 630, 628 is directed to top coating 212 as light 632.

[0058] The light 632 is recycled to the top coating 212 and randomized. The recycled light with the randomized polarization is again incident on the prism 622 and acquires the proper polarization and is emitted through the transmissive surface 640 as light 634 that is mostly polarized (greater than 50%, 75%, 80%, 90%, 95%, 99%, greater, or some percentage therebetween).

[0059] Figure 8 By way of example, a schematic diagram of a portion of a display device 800 providing p-polarized light to a screen 140 is shown. The illustrated polarization device includes three prisms 740, 742, 744. Prism 740 is coupled on a first side to the hypotenuse of prism 742. Prism 740 is coupled on a second side to the hypotenuse of prism 744. The hypotenuse of prism 740 faces the input surface 360 ​​of the light guide 120.

[0060] The polarization device polarizes the unpolarized light 746 from the light emitting element 130. The light 746 is received through a receiving surface 760 of the polarization device. The polarization device transmits the polarized light 750 through a transmitting surface 762 towards the input surface 360 ​​of the light guide 120.

[0061] Light from receiving surface 760 is incident on prisms 740, 742, 744. A portion of polarized (p-polarized) light 750 is transmitted from transmission surface 762. Another portion of light 750 is incident on film 738 and reflected to prisms 742, 744 as light 748. Film 738 may be an adhesive that connects prisms 740, 742, 744. Film 538 may be similar to film 338.

[0062] Light 748 is reflected by mirror 716 as light 752. Light 752 is again incident on film 738, and a portion of p-polarized light 752 is transmitted as light 750. Another portion of light 754 is directed toward top coating 212.

[0063] The light 754 is recycled to the top coating 212 and its polarization is randomized by the top coating 212. The recycled light with the randomized polarization is again incident on the prisms 742, 744 and acquires the proper polarization to be emitted out of the transmission surface 762 as light 750 that is predominantly p-polarized (greater than 50%, 75%, 80%, 90%, 95%, 99%, greater, or some percentage therebetween).

[0064] Reflector 716 may surround prisms 740, 742, 744, leaving transmissive surface 762 and receiving surface 760 exposed. Reflector 716 may be similar to reflectors 316, 318. Compared to display device 400, display device 700 is a thinner device with a slightly increased bezel length.

[0065] Fig. 9 Flowchart showing an example of a method 900 for forming a light emitting device according to some examples. The method 900 can be used to form - among other devices - Figure 4-6 Method 900 is only one method of forming a light emitting device; other suitable methods may also be used.

[0066] Method 900 may include: at operation 902, coupling a visible light emitting element to a circuit board and a frame of a back panel; at operation 904, placing a light guide panel including an input surface and a transmission surface, the transmission surface being substantially perpendicular to the input surface so that the input surface faces the light emitting element; and at operation 906, placing a polarization device including a prism to receive visible light from the light emitting element, polarize the visible light, and transmit the polarized light to the input surface of the light guide panel.

[0067] The polarization device may include two exposed surfaces, four non-exposed surfaces, and reflective components on the non-exposed surfaces. The method 900 may include, wherein the two exposed surfaces include a first surface facing the light emitting element and a second surface facing the input surface of the light guide panel. The method 900 may include, wherein the first surface is substantially perpendicular to the second surface, and the polarized light is s-polarized. The method 900 may include, wherein the first surface is substantially parallel to the second surface, and the polarized light is p-polarized.

[0068] Although the foregoing discussion relates to polarization in backlight applications, the same polarization device can be used in other applications. For example, the polarization device can be used in outdoor lighting devices (such as street lights). For example, polarized light can reduce reflections at (wet) planar surfaces. In another example, the backlight can be used in extended reality (XR) applications (e.g., augmented reality (AR), virtual reality (VR), or mixed reality (MR) applications).

[0069] Fig.10 A display system 960 is shown in accordance with some embodiments. System 960 includes an XR system 968, such as may be part of a communication or computing device (e.g., a smart phone, tablet / laptop) or another device (such as a projector). LED array 962 may be similar to the previous embodiments and may include a plurality of sets of LEDs driven by an LED driver 964, which is controlled by a controller 965 (such as a microprocessor). In some embodiments, controller 965 may be coupled to XR system 968 and sensor 966 and operate according to instructions and profiles stored in memory 967. In some embodiments, system 960 may include a module that allows wireless communication via Bluetooth, WiFi, Long Term Evolution (LTE), or any other communication protocol using transceiver circuitry.

[0070] The XR system 968 can incorporate a wide range of optics and optically reflective or transmissive surfaces. In some embodiments, the optics can be used to correct or minimize two-dimensional or three-dimensional optical errors, including pincushion distortion, barrel distortion, longitudinal chromatic aberration, spherical aberration, chromatic aberration, field curvature, astigmatism, or any other type of optical error. In some embodiments, optical elements can be used to magnify and / or correct images. The optical elements can include apertures, filters, Fresnel lenses, convex lenses, concave lenses, or any other suitable optical elements that affect projection. Additionally, one or more optical elements can have one or more coatings, including ultraviolet (UV) blocking coatings or anti-reflective coatings. In some embodiments, magnification of the displayed image allows the XR system 968 to be physically smaller, lighter, and require less power than larger displays. Additionally, magnification can increase the field of view of the displayed content, which allows the display to appear equal to the user's normal field of view.

[0071] In one embodiment, the LED driver 964 can be formed, for example, using an analog driver method or a pulse width modulation (PWM) driver method. When an analog driver is used, all LED sets driven together can be driven simultaneously. By providing different currents for each LED or LED set, each LED or LED set can be driven independently. In a PWM driver, each LED or LED set can be turned on in sequence at high speed and driven with substantially the same current. The color of the display can be controlled by changing the duty cycle of each color. In some embodiments, the current is supplied by a voltage-controlled current source.

[0072] As indicated above, the controller 965 can control the amount of current supplied and / or the duty cycle. The controller 965 can be a microprocessor including, for example, an application processor and a baseband processor. The sensor 966 can include, for example, a position sensor (e.g., a gyroscope and / or an accelerometer) and / or other sensors that can be used to determine the position, velocity, and orientation of the system 960. Signals from the sensor 966 can be supplied to the controller 965 for determining an appropriate course of action for the controller 965 (e.g., which image should be presented to the XR user).

[0073] The memory 967 may be a non-volatile memory. The memory 967 may store instructions and applications used by the controller 965 to control the driving of the LED array by the driver 964 based on a specific profile also stored therein. The instructions may take into account inputs from various sensors 966 and images to be streamed, overlaid, or otherwise supplied to the XR user.

[0074] The controller 965 can be any microprocessor capable of executing instructions (sequentially or otherwise) that specify the actions to be taken. As described above, the system 960 can include logic and various components and modules on which the controller 965 can operate. Modules and components are tangible entities (e.g., hardware) that can perform specified operations and can be configured or arranged in some way. In an example embodiment, the circuit can be arranged as a module in a specified manner (e.g., internally or relative to external entities such as other circuits). The controller 965 can be configured as a module (operating to perform specified operations) by firmware or software (e.g., instructions, application program parts, or applications). In an example embodiment, the software can reside on a machine-readable medium (such as a non-statutory machine-readable medium). In an example embodiment, when executed by the underlying hardware of the module, the software causes the hardware to perform the specified operation.

[0075] Thus, the term "module" (and "component") is understood to encompass a tangible entity, i.e., an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., provisionally) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any of the operations described herein. Considering an example where a module is temporarily configured, each module need not be instantiated at any one time. For example, where a module includes a general-purpose hardware processor configured using software, the general-purpose hardware processor can be configured into corresponding different modules at different times. Thus, software can configure a hardware processor, for example, to constitute a particular module at one time and to constitute a different module at a different time.

[0076] In operation, in some embodiments, the illumination of all pixels from the LED assembly 162 can be adjusted (deactivated), or the illumination intensity of the pixel can be reduced by a significant predetermined percentage (e.g., between about 10% and about 90%). In various embodiments, the adjustment can occur within a predetermined amount of time, or until manually overridden. Regardless of whether the illumination of all or only some pixels from the LED assembly 962 is adjusted, the illumination from some or all other pixels (within the same LED array (if present), or in a separate LED array) can also be adjusted or not adjusted. That is, some or all other pixels can be activated, if not activated, the illumination intensity of other pixels can be increased by a significant predetermined percentage (e.g., between about 10% and about 90%) when the pixel is activated, or the illumination intensity of other pixels can be unaffected by the pixel adjustment. In the latter case, the other pixels can therefore provide light at the same time and in the same position as the light from the pixel.

[0077] To further illustrate the devices and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples may exist independently, or may be arranged or combined in any manner with any one or more of the other examples.

[0078] In Example 1, a backlight device includes: a light emitting element configured to emit visible light; a polarization device including a prism positioned to receive the visible light and polarize the visible light to produce polarized light; and a light guide panel configured to receive the polarized light at an input surface facing the polarization device and distribute the polarized light to a main surface of the light guide panel facing the display screen.

[0079] In Example 2, Example 1 may further include, wherein the polarization device includes two exposed surfaces and four non-exposed surfaces, and further includes a reflective member on the non-exposed surfaces.

[0080] In Example 3, Example 2 can further include, wherein the two exposed surfaces include a first surface and a second surface, the first surface facing the light emitting element and the second surface facing an input surface of the light guide.

[0081] In Example 4, Example 3 may further include, wherein the first surface is substantially perpendicular to the second surface.

[0082] In Example 5, Example 4 may further include, wherein the polarized light is s-polarized.

[0083] In Example 6, at least one of Examples 3-5 may further include, wherein the first surface is substantially parallel to the second surface.

[0084] In Example 7, Example 6 may further include, wherein the polarized light is p-polarized.

[0085] In Example 8, at least one of Examples 2-7 may further include, wherein the reflective component includes a reflective coating or a reflective mirror.

[0086] In Example 9, at least one of Examples 1-8 may further include, wherein the prism is a first prism, and the polarization device includes a second prism attached to the first prism.

[0087] In Example 10, Example 9 may further include a film between the first and second prisms.

[0088] Example 11 includes a method of forming a backlight device, the method comprising: coupling a visible light emitting element to a circuit board and a frame of a back panel; placing a light guide panel including an input surface and a transmission surface, the transmission surface being substantially perpendicular to the input surface so that the input surface faces the light emitting element; and placing a polarization device including a prism to receive visible light from the light emitting element, polarize the visible light, and transmit the polarized light to the input surface of the light guide panel.

[0089] In Example 12, Example 11 may further include, wherein the polarization device includes two exposed surfaces, four non-exposed surfaces, and reflective components on the non-exposed surfaces.

[0090] In Example 13, Example 12 may further include, wherein the two exposed surfaces include a first surface facing the light emitting element and a second surface facing the input surface of the light guide panel.

[0091] In Example 14, Example 13 may further include, wherein the first surface is substantially perpendicular to the second surface, and the polarized light is s-polarized.

[0092] In Example 15, at least one of Examples 13-14 may further include, wherein the first surface is substantially parallel to the second surface, and the polarized light is p-polarized.

[0093] Example 16 includes a display device comprising: a back panel; a light emitting element located within a frame of the back panel and configured to emit visible light; a polarization device including a prism positioned to receive visible light and polarize the visible light to produce polarized light; a light guide panel configured to receive polarized light at an input surface facing the polarization device and distribute the polarized light to a major surface of the light guide panel; and a display screen for receiving light from the major surface.

[0094] In Example 17. Example 16 can further include, wherein the polarization device includes two exposed surfaces, four non-exposed surfaces, and reflective components on the non-exposed surfaces.

[0095] In Example 18, at least one of Examples 16-17 may further include, wherein the two exposed surfaces include a first surface facing the light emitting element and a second surface facing the input surface of the light guide.

[0096] In Example 19, Example 18 may further include, wherein the first surface is substantially perpendicular to the second surface, and the polarized light is s-polarized.

[0097] In Example 20, at least one of Examples 18-19 may further include, wherein the first surface is substantially parallel to the second surface, and the polarized light is p-polarized.

[0098] Although embodiments of the disclosed subject matter have been shown and described herein, it will be apparent to those skilled in the art that these embodiments are provided by way of example only. Without departing from the disclosed subject matter, those skilled in the art will appreciate many variations, changes, and substitutions upon reading and understanding the materials provided herein. It should be understood that in practicing the various embodiments of the disclosed subject matter, various alternatives to the embodiments of the disclosed subject matter described herein may be employed. It is intended that the following claims define the scope of the disclosed subject matter, and that methods and structures within the scope of these claims and their equivalents are covered thereby.

Claims

1. A display device, comprising: a light emitting element comprising a top coating and a side coating and configured to emit visible light; a polarization device, arranged to receive the unpolarized visible light emitted by the light emitting element and generate polarized light, the polarization device comprising a receiving surface and a transmitting surface, the receiving surface facing the light emitting element, wherein the polarization device comprises: - multiple prisms, - a reflector arranged to surround the prism so that said transmission surface and said receiving surface are exposed, and - a membrane located between the prisms, wherein a portion of the light reflected by the reflector and transmitted by the film is recycled to the top coating and randomized, and wherein the recycled light having the randomized polarization is again incident on the prisms of the polarization device; and A light guide panel is configured to receive the polarized light at an input surface facing a transmissive surface of the polarization device and distribute the polarized light to a major surface of the light guide panel facing a display screen of the display device. The display device according to claim 1 , wherein the receiving surface is perpendicular to the transmitting surface. The display device according to claim 2 , wherein the polarized light is s-polarized. The display device according to claim 1 , wherein the receiving surface is parallel to the transmitting surface. The display device of claim 4 , wherein the polarized light is p-polarized.

6. A display device according to any one of claims 1 to 5, wherein the prisms comprise a birefringent crystalline material.

7. The display device according to any one of claims 1 to 5, wherein the film comprises any one of the following: polyester, epoxy, or urethane based adhesive.

8. The display device according to any one of claims 1 to 5, wherein the film comprises a multi-layer structure.

9. A display device according to any one of claims 1 to 5, wherein the film comprises a layer of adhesive and alternating layers of high refractive index material and low refractive index material.

10. A display device according to any one of claims 1 to 5, wherein the film is configured to separate orthogonal polarisation components of light using the Brewster angle in each layer.

11. The display device according to any one of claims 1 to 5, comprising: back panel; and wherein The light emitting element is located in the frame of the back plate.

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