WO2024136897A1 - Rétroéclairage à collimation automatique, affichage multivue et procédé - Google Patents

Rétroéclairage à collimation automatique, affichage multivue et procédé Download PDF

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Publication number
WO2024136897A1
WO2024136897A1 PCT/US2022/082101 US2022082101W WO2024136897A1 WO 2024136897 A1 WO2024136897 A1 WO 2024136897A1 US 2022082101 W US2022082101 W US 2022082101W WO 2024136897 A1 WO2024136897 A1 WO 2024136897A1
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WO
WIPO (PCT)
Prior art keywords
light
guided
aperture
light guide
multibeam
Prior art date
Application number
PCT/US2022/082101
Other languages
English (en)
Inventor
David A. Fattal
Thomas HOEKMAN
Colton BUKOWSKY
Ming Ma
Original Assignee
Leia Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Leia Inc. filed Critical Leia Inc.
Priority to PCT/US2022/082101 priority Critical patent/WO2024136897A1/fr
Publication of WO2024136897A1 publication Critical patent/WO2024136897A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0025—Diffusing sheet or layer; Prismatic sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0031—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices

Definitions

  • Electronic displays are a nearly ubiquitous medium for communicating information to users of a wide variety of devices and products.
  • Most commonly employed electronic displays include the cathode ray tube (CRT), plasma display panels (PDP), liquid crystal displays (LCD), electroluminescent displays (EL), organic light emitting diode (OLED) and active-matrix OLEDs (AMOLED) displays, electrophoretic displays (EP) and various displays that employ electromechanical or electrofluidic light modulation (e.g., digital micromirror devices, electrowetting displays, etc.).
  • CTR cathode ray tube
  • PDP plasma display panels
  • LCD liquid crystal displays
  • EL electroluminescent displays
  • OLED organic light emitting diode
  • AMOLED active-matrix OLEDs
  • EP electrophoretic displays
  • electronic displays may be categorized as either active displays (i.e., displays that emit light) or passive displays (i.e., displays that modulate light provided by another source).
  • Examples of active displays include CRTs, PDPs and OLEDs/ AMOLED s.
  • Displays that are typically classified as passive when considering emitted light are LCDs and EP displays.
  • Passive displays while often exhibiting attractive performance characteristics including, but not limited to, inherently low power consumption, may find somewhat limited use in many practical applications given the lack of an ability to emit light.
  • Figure 1 illustrates a perspective view of a multiview display in an example, according to an embodiment consistent with the principles described herein.
  • Figure 2 illustrates a graphical representation of angular components of a light beam having a particular principal angular direction corresponding to a view direction of a multiview display in an example, according to an embodiment consistent with the principles described herein.
  • Figure 3 illustrates a side view of an example of a multiview display that includes a self-collimating backlight, according to an embodiment consistent with the principles described herein.
  • Figure 4 illustrates a top view of the self-collimating backlight of the display of Figure 3, according to an embodiment consistent with the principles described herein.
  • Figure 8 illustrates a plan view of a multiview display including a multibeam backlight in an example, according to an embodiment consistent with the principles described herein.
  • Figure 9 illustrates a perspective view of a multiview display including a multibeam backlight in an example, according to an embodiment consistent with the principles described herein.
  • Figure 10 illustrates a cross sectional view of a portion of a multibeam backlight including a multibeam element in an example, according to an embodiment consistent with the principles described herein.
  • Figure 11 illustrates a cross sectional view of a portion of a multibeam backlight including a multibeam element in an example, according to another embodiment consistent with the principles described herein.
  • Figure 12 illustrates a cross sectional view of a portion of a multibeam backlight including a multibeam element in an example, according to another embodiment consistent with the principles described herein.
  • Figure 13 illustrates a cross sectional view of a portion of a multibeam backlight including a multibeam element in an example, according to another embodiment consistent with the principles described herein.
  • Figure 14 illustrates a cross sectional view of a portion of a multibeam backlight including a multibeam element in an example, according to another embodiment consistent with the principles described herein.
  • Figure 15 illustrates a schematic drawing of an example of a multiview display, according to an embodiment consistent with the principles described herein.
  • Figure 16 illustrates a flow chart of an example of a method of backlight operation, according to an embodiment consistent with the principles described herein.
  • Certain examples and embodiments have other features that are one of in addition to and in lieu of the features illustrated in the above-referenced figures. These and other features are detailed below with reference to the above-referenced figures.
  • the self-collimating backlight may include a light guide that may guide light as guided light.
  • the self-collimating backlight may include an aperture layer located within the light guide.
  • the aperture layer may include an aperture that may reduce an angular spread of the guided light that passes through the aperture. The angular spread may be reduced in a horizontal direction parallel to a guiding surface of the light guide and perpendicular to a propagation direction of the guided light.
  • the self-collimating backlight may include a scattering element aligned with the aperture. The scattering element may scatter out a portion of the guided light received from the aperture and having the reduced angular spread as emitted light of the self-collimating backlight.
  • Inclusion of the aperture layer and the aperture within the light guide can help reduce an angular spread of guided light within the light guide. Such a reduced angular spread of the guided light may, in turn, reduce an angular spread of the emitted light that is output from the light guide. Such a reduced angular spread may be beneficial for some applications, such as for a multiview display.
  • Including the aperture layer and the aperture within the light guide can help loosen the collimation requirements of a light source that directs light into the light guide, and may allow collimating optics, such as a collimating lens, to be omitted from the light source, thereby reducing a cost and a complexity of the light source.
  • the aperture layer and the aperture may be formed at a wafer level, such as by lithographic techniques, the aperture may be aligned to a scattering element with high precision, thereby reducing or eliminating a need to actively or passively align collimating optics to a light-producing element in the light source.
  • Figure 1 illustrates a perspective view of a multiview display 10 in an example, according to an embodiment consistent with the principles described herein.
  • the multiview display 10 comprises a screen 12 to display a multiview image to be viewed.
  • the multiview display 10 provides different views 14 of the multiview image in different view directions 16 relative to the screen 12.
  • the view directions 16 are illustrated as arrows extending from the screen 12 in various different principal angular directions.
  • the different views 14 are illustrated as shaded polygonal boxes at the termination of the arrows (i.e., depicting the view directions 16). Only four views 14 and four view directions 16 are illustrated, all by way of example and not limitation.
  • a view direction or equivalently a light beam having a direction corresponding to a view direction of a multiview display generally has a principal angular direction given by angular components ⁇ 6, ⁇ /) ⁇ , by definition herein.
  • the angular component is referred to herein as the ‘elevation component’ or ‘elevation angle’ of the light beam.
  • the angular component is referred to as the ‘azimuth component’ or ‘azimuth angle’ of the light beam.
  • the elevation angle # is an angle in a vertical plane (e.g., perpendicular to a plane of the multiview display screen while the azimuth angle is an angle in a horizontal plane (e.g., parallel to the multiview display screen plane).
  • Figure 2 illustrates a graphical representation of the angular components ⁇ 6, (f> ⁇ of a light beam 20 having a particular principal angular direction corresponding to a view direction (e.g., view direction 16 in Figure 1) of a multiview display in an example, according to an embodiment consistent with the principles described herein.
  • the light beam 20 is emitted or emanates from a particular point, by definition herein. That is, by definition, the light beam 20 has a central ray associated with a particular point of origin within the multiview display.
  • Figure 2 also illustrates the light beam (or view direction) point of origin O.
  • multiview as used in the terms ‘multiview image’ and ‘multiview display’ is defined as a plurality of views representing different perspectives or including angular disparity between views of the view plurality.
  • multiview explicitly includes more than two different views (i.e., a minimum of three views and generally more than three views), by definition herein.
  • ‘multiview display’ as employed herein is explicitly distinguished from a stereoscopic display that includes only two different views to represent a scene or an image.
  • multiview images and multiview displays include more than two views
  • multiview images may be viewed (e.g., on a multiview display) as a stereoscopic pair of images by selecting only two of the multiview views to view at a time (e.g., one view per eye).
  • a ‘multiview pixel’ is defined herein as a set of sub-pixels representing ‘view’ pixels in each of a similar plurality of different views of a multiview display.
  • a multiview pixel may have an individual sub-pixel corresponding to or representing a view pixel in each of the different views of the multiview image.
  • the sub-pixels of the multiview pixel are so-called ‘directional pixels’ in that each of the sub-pixels is associated with a predetermined view direction of a corresponding one of the different views, by definition herein.
  • the different view pixels represented by the subpixels of a multiview pixel may have equivalent or at least substantially similar locations or coordinates in each of the different views.
  • a first multiview pixel may have individual sub-pixels corresponding to view pixels located at ⁇ i, yi ⁇ in each of the different views of a multiview image
  • a second multiview pixel may have individual sub-pixels corresponding to view pixels located at ⁇ X2, 2 ⁇ in each of the different views, and so on.
  • a ‘light guide’ is defined as a structure that guides light within the structure using total internal reflection.
  • the light guide may include a core that is substantially transparent at an operational wavelength of the light guide.
  • the term ‘light guide’ generally refers to a dielectric optical waveguide that employs total internal reflection to guide light at an interface between a dielectric material of the light guide and a material or medium that surrounds that light guide.
  • a condition for total internal reflection is that a refractive index of the light guide is greater than a refractive index of a surrounding medium adjacent to a surface of the light guide material.
  • the light guide may include a coating in addition to or instead of the aforementioned refractive index difference to further facilitate the total internal reflection.
  • the coating may be a reflective coating, for example.
  • the light guide may be any of several light guides including, but not limited to, one or both of a plate or slab guide and a strip guide.
  • a plate when applied to a light guide as in a ‘plate light guide’ is defined as a piece-wise or differentially planar layer or sheet, which is sometimes referred to as a ‘slab’ guide.
  • a plate light guide is defined as a light guide configured to guide light in two substantially orthogonal directions bounded by a top surface and a bottom surface (i.e., opposite surfaces) of the light guide.
  • the top and bottom surfaces are both separated from one another and may be substantially parallel to one another in at least a differential sense. That is, within any differentially small section of the plate light guide, the top and bottom surfaces are substantially parallel or co-planar.
  • the plate light guide may be substantially flat (i.e., confined to a plane) and therefore, the plate light guide is a planar light guide.
  • the plate light guide may be curved in one or two orthogonal dimensions.
  • the plate light guide may be curved in a single dimension to form a cylindrical shaped plate light guide.
  • any curvature has a radius of curvature sufficiently large to ensure that total internal reflection is maintained within the plate light guide to guide light.
  • a collimator is defined as substantially any optical device or apparatus that is configured to collimate light.
  • a collimator may include, but is not limited to, a collimating mirror or reflector, a collimating lens, a diffraction grating, and various combinations thereof.
  • the collimator comprising a collimating reflector may have a reflecting surface characterized by a parabolic curve or shape.
  • the collimating reflector may comprise a shaped parabolic reflector.
  • the collimator may be a continuous reflector or a continuous lens (i.e., a reflector or lens having a substantially smooth, continuous surface).
  • the collimating reflector or the collimating lens may comprise a substantially discontinuous surface such as, but not limited to, a Fresnel reflector or a Fresnel lens that provides light collimation.
  • an amount of collimation provided by the collimator may vary in a predetermined degree or amount from one embodiment to another.
  • the collimator may be configured to provide collimation in one or both of two orthogonal directions (e.g., a vertical direction and a horizontal direction). That is, the collimator may include a shape in one or both of two orthogonal directions that provides light collimation, according to some embodiments.
  • the light rays of the collimated light beam may have a Gaussian distribution in terms of angle and the angular spread be an angle determined by at one-half of a peak intensity of the collimated light beam, according to some examples.
  • a ‘light source’ is defined as a source of light (e.g., an optical emitter configured to produce and emit light).
  • the light source may comprise an optical emitter such as a light emitting diode (LED) that emits light when activated or turned on.
  • LED light emitting diode
  • the light source may be substantially any source of light or comprise substantially any optical emitter including, but not limited to, one or more of a light emitting diode (LED), a laser, an organic light emitting diode (OLED), a polymer light emitting diode, a plasma-based optical emitter, a fluorescent lamp, an incandescent lamp, and virtually any other source of light.
  • the light produced by the light source may have a color (i.e., may include a particular wavelength of light), or may be a range of wavelengths (e.g., white light).
  • the light source may comprise a plurality of optical emitters.
  • a ‘multiview image’ is defined as a plurality of images (i.e., greater than three images) wherein each image of the plurality represents a different view corresponding to a different view direction of the multiview image.
  • the multiview image is a collection of images (e.g., two-dimensional images) which, when display on a multiview display, may facilitate a perception of depth and thus appear to be an image of a 3D scene to a viewer, for example.
  • a multiview image that provides pairs of views that represent different but related perspectives of a 3D scene consistent with viewing by a viewer is defined as a 3D image.
  • ‘broad-angle’ emitted light is defined as light having a cone angle that is greater than a cone angle of the view of a multiview image or multiview display.
  • the broad-angle emitted light may have a cone angle that is greater than about twenty degrees (e.g., > ⁇ 20°).
  • the broad-angle emitted light cone angle may be greater than about thirty degrees (e.g., > ⁇ 30°), or greater than about forty degrees (e.g., > ⁇ 40°), or greater than fifty degrees (e.g., > ⁇ 50°).
  • the cone angle of the broad-angle emitted light may be about sixty degrees (e.g., > ⁇ 60°).
  • the broad-angle emitted light cone angle may be about the same as a viewing angle of an LCD computer monitor, an LCD tablet, an LCD television, or a similar digital display device meant for broad-angle viewing (e.g., about ⁇ 40-65°).
  • broad-angle emitted light may also be characterized or described as diffuse light, substantially diffuse light, non-directional light (i.e., lacking any specific or defined directionality), or as light having a single or substantially uniform direction.
  • the article ‘a’ is intended to have its ordinary meaning in the patent arts, namely ‘one or more’.
  • ‘a lens’ means one or more lenses and as such, ‘the lens’ means ‘the lens or lenses’ herein.
  • any reference herein to ‘top’, ‘bottom’, ‘upper’, ‘lower’, ‘up’, ‘down’, ‘front’, back’, ‘first’, ‘second’, ‘left’ or ‘right’ is not intended to be a limitation herein.
  • the term ‘about’ when applied to a value generally means within the tolerance range of the equipment used to produce the value, or may mean plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless otherwise expressly specified.
  • Figure 3 illustrates a side view of an example of a multiview display 300 that includes a self-collimating backlight 330, according to an embodiment consistent with the principles described herein.
  • Figure 4 illustrates a top view of the self-collimating backlight 330 of the display of Figure 3, according to an embodiment consistent with the principles described herein.
  • the self-collimating backlight 330 may include a light guide 314 configured to guide light as guided light 104. Details regarding some structures and operation of the light guide 314 are provided below, for example, with regard to the light guide 114 shown in Figures 7-14. Details regarding the guided light 104 are provided below, for example, with regard to Figures 7 and 10-14.
  • the self-collimating backlight 330 may further include an aperture layer 332 located within the light guide 314.
  • the aperture layer 332 may include an aperture 334 configured to reduce an angular spread 338 of the guided light 104 that passes through the aperture 334.
  • the aperture layer 332 may include an aperture structure that defines the aperture 334.
  • the angular spread 338 may be reduced in a horizontal direction parallel to a guiding surface of the light guide 314 and perpendicular to a propagation direction of the guided light 104 (e.g., the angular spread 338 may be reduced in the x-direction).
  • the light guide 114 shown in Figures 7-14 lacks the aperture layer 332, other aspects regarding the structure and function of the light guide 314 are similar to the light guide 114 and will be readily understood in light of the present disclosure.
  • the self-collimating backlight 330 may further include a scattering element 316 aligned with the aperture 334.
  • the scattering element 316 is configured to scatter out a portion of the guided light 104 that is received from the aperture 334 and has the reduced angular spread 338.
  • the scattered-out portion of the guided light 104 may form emitted light 336 of the self-collimating backlight 330.
  • the scattering element may be positioned on either of the opposing light-guiding surfaces of the light guide 314, or in an interior of the light guide 314.
  • the scattering element may include one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element.
  • the scattering element 316 may include a multibeam element, such as multibeam element 116 (see Figures 7-14). Details regarding the structure and operation of the scattering element 316 (for example, location of the scattering element and physical principles that cause the scattering) are provided below with regard to the multibeam element 116 shown in Figures 7-14.
  • the scattering element 316 may include a multibeam element, such as multibeam element 116, that may scatter out the portion of the guided light 104 as emitted light having a plurality of directional light beams with propagation directions corresponding to respective view directions of the multiview display 300.
  • the multibeam element 116 may include one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element.
  • the diffraction grating may be configured to diffractively scatter out the guided light portion as the directional light beam plurality.
  • the micro-reflective element may be configured to reflectively scatter out the guided light portion as the directional light beam plurality.
  • the micro-refractive element may be configured to refractively scatter out the guided light portion as the directional light beam plurality.
  • the aperture layer 332 may include a plurality of apertures 334, such as apertures 334A, 334B, 334C, and 334D, configured to reduce an angular spread 338 of guided light 104 in a horizontal direction parallel to a guiding surface of the light guide 314.
  • the self-collimating backlight 330 may include an array of scattering elements 316, such as 316A, 316B, 316C, and 316D arranged along the light guide 314.
  • Each scattering element 316 of the scattering element array may be aligned with a corresponding aperture 334 of the aperture layer 332 and may be configured to scatter out a portion of the guided light 104 received from the aperture 334 as directional light beams having directions corresponding to view directions of the multiview display 300.
  • the self-collimating backlight 330 may optionally include multiple aperture layers located within the light guide 314, each aperture layer defining one or more apertures that may reduce an angular spread of guided light 104 incident on respective scattering elements.
  • the multiview display 300 may further include a light valve array 120 configured to modulate directional light beams of the directional light beam plurality to provide a multiview image.
  • a size of the scattering element 316 may be between one quarter and two times a size of a light valve of the light valve array 120. Details regarding the structure and operation of the light valve array 120 are provided below with regard to Figures 7 and 9.
  • the self-collimating backlight 330 may further include a light source 118 configured to provide the light to be guided as the guided light 104.
  • the guided light 104 may have a predetermined collimation factor and a non-zero propagation angle in a vertical direction perpendicular to the horizontal direction within the light guide 314 (e.g., the guided light 104 may have a non-zero propagation angle in the z-direction). Details regarding the structure and operation of the light source 118 are provided below with regard to Figures 7 and 9.
  • the multiview display 300 may further include a controller 340.
  • the controller may control the light source 318, such as by sending instructions to the light source 318 to produce light at a specified optical power level.
  • the controller may control the light valve array 120, such as by receiving a video signal (not shown) and sending instructions to the light valve array 120 to modulate light passing through the light valves to produce a video image that corresponds to the video signal.
  • the controller 340 may be implemented using a variety of devices and circuits including, but not limited to, one or more of integrated circuits (ICs), very large scale integrated (VLSI) circuits, application specific integrated circuits (ASIC), field programmable gate arrays (FPGAs), digital signal processors (DSPs), graphical processor unit (GPU), and the like, firmware, software (such as a program module or a set of instructions), and a combination of two or more of the above.
  • ICs integrated circuits
  • VLSI very large scale integrated circuits
  • ASIC application specific integrated circuits
  • FPGAs field programmable gate arrays
  • DSPs digital signal processors
  • GPU graphical processor unit
  • firmware software
  • firmware such as a program module or a set of instructions
  • an embodiment or elements thereof may be implemented as circuit elements within an ASIC or a VLSI circuit. Implementations that employ an ASIC or a VLSI circuit are examples of hardware-based circuit implementations.
  • an embodiment may be implemented as software using a computer programming language (e.g., C/C++) that is executed in an operating environment or a software-based modeling environment (e.g., MATLAB®, MathWorks, Inc., Natick, MA) that is further executed by a computer (e.g., stored in memory and executed by a processor or a graphics processor of a general-purpose computer).
  • a computer programming language e.g., C/C++
  • a software-based modeling environment e.g., MATLAB®, MathWorks, Inc., Natick, MA
  • a computer e.g., stored in memory and executed by a processor or a graphics processor of a general-purpose computer.
  • the programming language may be compiled or interpreted, e.g., configurable or configured (which may be used interchangeably in this discussion), to be executed by a processor or a graphics processor of a computer.
  • a block, a module or an element of an apparatus, device or system may be implemented using actual or physical circuitry (e.g., as an IC or an ASIC), while another block, module or element may be implemented in software or firmware.
  • some embodiments may be implemented using a substantially hardware-based circuit approach or device (e.g., ICs, VLSI, ASIC, FPGA, DSP, firmware, etc.), while other embodiments may also be implemented as software or firmware using a computer processor or a graphics processor to execute the software, or as a combination of software or firmware and hardware-based circuitry, for example.
  • Figure 5 illustrates a perspective view of an example of the aperture 334’ of Figure 4, according to an embodiment consistent with the principles described herein.
  • the aperture layer 332 ( Figure 3) may include a pair of lightblocking elements 502A, 502B spaced apart from each other in the horizontal direction (e.g., spaced apart in the x-direction).
  • the aperture 334’ may be defined as a space between the light-blocking elements 502A, 502B.
  • the pair of light-blocking elements 502A, 502B may include parallel strips that extend along a length of the light guide 314 in the propagation direction of the guide light (e.g., extend in the y- direction).
  • the parallel strips are longer along the horizontal direction (e.g. in the -direction) than in the vertical direction (e.g. in the z-direction).
  • the pair of light-blocking elements 502A, 502B may reduce a collimation factor (e.g., may reduce a range of propagation angles) of light passing between the light-blocking elements 502A, 502B.
  • the lightblocking elements 502A, 502B may define a geometry to block guided light 104 that propagates with a propagation angle that lies outside of an angular range 504, where the angular range 504 is in the x-direction.
  • the light-blocking elements 502A, 502B may include a metal film configured to block light by reflection.
  • the metal film may include chrome, aluminum, or any suitable metal. The metal film may effectively recirculate light within the light guide 314, which may help conserve electrical power used by the light source 118.
  • the light-blocking elements 502A, 502B may include an opaque material configured to absorb light.
  • the opaque material may include a dye that absorbs all or most of the light.
  • the opaque material may absorb light and effectively remove the light from circulation within the light guide 314.
  • the removed light may be converted to heat and dissipated in the light guide 314.
  • the amount of heat generated may be relatively small, so that the light guide 314 may not experience local heating or significant temperature differentials.
  • the light guide 314 may include a light guide material having a first index of refraction.
  • the light-blocking elements 502A, 502B may include a light-blocking element material having a second index of refraction that is less than the first index of refraction.
  • the light-blocking elements 502A, 502B may be configured to block light by reflection from an interface between the light guide material and the light-blocking element material. In some embodiments, the reflection at the interface may be total internal reflection.
  • Figure 6 illustrates a perspective view of another example of the aperture 334” of Figure 4, according to an embodiment consistent with the principles described herein.
  • the aperture 334 may be U-shaped or horseshoe-shaped.
  • the aperture layer 332 may additionally or alternatively include a light-blocking element 602 spanning between the pair of light-blocking elements 502A, 502B.
  • the pair of light-blocking elements 502A, 502B may extend along the j'-direction, each light-blocking element of the pair of light-blocking elements 502A, 502B may have a first end facing the positive j'-di recti on, and the other light-blocking element 602 may connect the first ends of the pair of light-blocking elements 502A, 502B.
  • the other light-blocking element 602 may define a length of the aperture 334” in the propagation direction (e.g. in the j'-direction).
  • the other lightblocking element 602 may at least partially reduce a collimation factor (e.g., may reduce a range of propagation angles) of light passing between the light-blocking elements 502A, 502B.
  • the other light-blocking element 602 may define a geometry to block guided light 104 that propagates with a propagation angle that lies outside of an angular range 604, where the angular range 604 is in the -direction.
  • the scattering element 316 associated with the aperture 334” may be located away from the aperture layer 332, such as between the aperture layer 332 and one of the light-guiding surface of the light guide 314.
  • Figure 7 illustrates a cross sectional view of a multiview display 100 including a multibeam backlight 110 in an example, according to an embodiment consistent with the principles described herein.
  • Figure 8 illustrates a plan view of a multiview display 100 including a multibeam backlight 110 in an example, according to an embodiment consistent with the principles described herein.
  • Figure 9 illustrates a perspective view of a multiview display 100 including a multibeam backlight 110 in an example, according to an embodiment consistent with the principles described herein. The perspective view in Figure 9 is illustrated with a partial cut-away to facilitate discussion herein only.
  • Figures 7-9 also illustrate a light valve array 120 positioned above the multibeam backlight 110, as is described further below.
  • the multibeam backlight 110 illustrated in Figures 7-9 is configured to provide a plurality of coupled-out light beams 112 having different principal angular directions from one another (e.g., as a light field).
  • the provided plurality of coupled-out light beams 112 are directed away from the multibeam backlight 110 in different principal angular directions that correspond to respective view directions of the multiview display 100, according to various embodiments.
  • the coupled-out light beams 112 may be modulated (e.g., using light valves of a light valve array 120, as described herein) to facilitate the display of information having 3D content as a multiview image by the multiview display 100.
  • the multibeam backlight 110 comprises a light guide 114.
  • the light guide 114 is an example of the light guide 314.
  • the light guide 114 is shown as lacking the aperture layer 332, but being otherwise similar in structure and function to the light guide 314.
  • the light guide 114 may be a plate light guide, according to some embodiments.
  • the light guide 114 is configured to guide light along a length of the light guide 114 as guided light 104, for example having a direction indicated by bold arrows 103.
  • the light guide 114 may include a dielectric material configured as an optical waveguide, for example.
  • the dielectric material may have a first refractive index that is greater than a second refractive index of a medium surrounding the dielectric optical waveguide. The difference in refractive indices is configured to facilitate total internal reflection of the guided light 104 according to one or more guided modes of the light guide 114.
  • the light guide 114 may be a slab or plate optical waveguide comprising an extended, substantially planar sheet of optically transparent, di electric material.
  • the optically transparent material of the light guide 114 may include or be made up of any of a variety of dielectric materials including, but not limited to, one or more of various types of glass (e.g., silica glass, alkali-aluminosilicate glass, borosilicate glass, etc.), one or more substantially optically transparent plastics or polymers (e.g., poly(methyl methacrylate) or 'acrylic glass', polycarbonate, etc.) or a combination thereof.
  • glass e.g., silica glass, alkali-aluminosilicate glass, borosilicate glass, etc.
  • substantially optically transparent plastics or polymers e.g., poly(methyl methacrylate) or 'acrylic glass', polycarbonate, etc.
  • the light guide 114 may further include a cladding layer (not illustrated) on at least a portion of a surface (e.g., one or both of the top surface and the bottom surface) of the light guide 114.
  • the cladding layer may be used to further facilitate total internal reflection.
  • the light guide 114 is configured to guide the guided light 104 at a non-zero propagation angle between a first surface 114' (e.g., 'front' surface or side) and a second surface 114" (e.g., 'back' surface or side) of the light guide 114.
  • the guided light 104 may propagate by reflecting or 'bouncing' between the first surface 114' and the second surface 114" of the light guide 114 at the non-zero propagation angle (albeit in a propagation direction indicated by the bold arrows 103).
  • a plurality of beams of the guided light 104 comprising different colors of light may be guided by the light guide 114 at respective ones of different colorspecific, non-zero propagation angles. Note that the non-zero propagation angle is not illustrated in Figures 7-9 for simplicity of illustration.
  • a 'non-zero propagation angle' is an angle relative to a surface (e.g., the first surface 114' or the second surface 114") of the light guide 114. Further, the non-zero propagation angle is both greater than zero and less than a critical angle of total internal reflection within the light guide 114, in accordance with the principles described herein.
  • the non-zero propagation angle of the guided light 104 may be between about ten (10) degrees and about fifty (50) degrees or, in some examples, between about twenty (20) degrees and about forty (40) degrees, or between about twenty -five (25) degrees and about thirty-five (35) degrees.
  • the nonzero propagation angle may be about thirty (30) degrees.
  • the non-zero propagation angle may be about 20 degrees, or about 25 degrees, or about 35 degrees.
  • a specific non-zero propagation angle may be chosen (e.g., arbitrarily) for a particular implementation as long as the specific non-zero propagation angle is chosen to be less than the critical angle of total internal reflection within the light guide 114.
  • the guided light 104 in the light guide 114 may be introduced or coupled into the light guide 114 at the non-zero propagation angle (e.g., about 30-35 degrees).
  • One or more of a lens, a mirror or similar reflector (e.g., a tilted collimating reflector), and a prism may facilitate coupling light into an input end of the light guide 114 as the guided light 104 at the non-zero propagation angle, for example.
  • the guided light 104 propagates along the light guide 114 in a direction that may be generally away from the input end (e.g., illustrated by bold arrows 103 pointing along an x-axis in Figure 7).
  • the guided light 104 or equivalently a guided light beam produced by coupling light into the light guide 114 is a collimated beam of light in accordance with the principles described herein.
  • a 'collimated light' or 'collimated light beam' is generally defined as a beam of light in which rays of the light beam are substantially parallel to one another within the light beam (e.g., the guided light 104). Further, rays of light that diverge or are scattered from the collimated light beam are not considered to be part of the collimated light beam, by definition herein.
  • the multibeam backlight 110 may include a collimator, such as a lens, reflector or mirror, as described above, (e.g., tilted collimating reflector) to collimate the light, e.g., from a light source.
  • the light source comprises a collimator.
  • the collimated light provided to the light guide 114 is a collimated light beam to be guided.
  • the guided light 104 may be collimated according to or having a collimation factor c, in various embodiments.
  • the light guide 114 may be configured to 'recycle' the guided light 104.
  • the guided light 104 that has been guided along the light guide length may be redirected back along that length in another, different propagation direction indicated by bold arrow 103'.
  • the light guide 114 may include a reflector (not illustrated) at an end of the light guide 114 opposite to an input end adjacent to the light source.
  • the reflector may be configured to reflect the guided light 104 back toward the input end as recycled guided light. Recycling guided light in this manner may increase a brightness of the multibeam backlight 110 (e.g., an intensity of the coupled-out light beams 112) by making guided light 104 available more than once, for example, to the multibeam elements, described below.
  • the bold arrow 103' indicating another propagation direction of recycled guided light illustrates a general propagation direction of the recycled guided light within the light guide 114 that was introduced into the light guide 114 from the aforementioned input end.
  • light may be introduced into the light guide 114 at the end opposite to the aforementioned input end that has the other propagation direction (i.e., bold arrow 103' directed in a negative x-direction), e.g., in addition to the guided light 104 from the aforementioned input end having the propagation direction indicated by the bold arrows 103.
  • the other propagation direction i.e., bold arrow 103' directed in a negative x-direction
  • the multibeam backlight 110 further comprises a plurality of multibeam elements 116 spaced apart from one another along the light guide length (x-direction).
  • the multibeam elements 116 of the element plurality are separated from one another by a finite space and represent individual, distinct elements along the light guide length. That is, by definition herein, the multibeam elements 116 of the plurality are spaced apart from one another according to a finite (i.e., non-zero) inter-element distance (e.g., a finite center-to-center distance).
  • the multibeam elements 116 of the element plurality generally do not intersect, overlap or otherwise touch one another, according to some embodiments. That is, each multibeam element 116 of the element plurality is generally distinct and separated from other ones of the multibeam elements 116.
  • the multibeam elements 116 of the plurality may be arranged in either a one-dimensional (ID) array or two-dimensional (2D) array.
  • the plurality of multibeam elements 116 may be arranged as a linear ID array.
  • the plurality of multibeam elements 116 may be arranged as a rectangular 2D array or as a circular 2D array.
  • the array i.e., ID or 2D array
  • the array may be a regular or uniform array, in some examples.
  • an interelement distance (e.g., center-to-center distance or spacing) between the multibeam elements 116 may be substantially uniform or constant across the array.
  • the inter-element distance between the multibeam elements 116 may be varied one or both of across (y-direction) the array and along the length (x-direction) of the light guide 114.
  • a multibeam element 116 of the element plurality is configured to couple out a portion of the guided light 104 as the plurality of coupled-out light beams 112.
  • Figures 7 and 9 illustrate the coupled-out light beams 112 as a plurality of diverging arrows depicted as being directed way from the first (or front) surface 114' of the light guide 114.
  • a size of the multibeam element 116 is comparable to a size of a 'sub-pixel' in a multiview pixel or equivalently, is comparable to a size of a light valve in the light valve array 120, according to various embodiments.
  • the 'size' may be defined in any of a variety of manners to include, but not be limited to, a length, a width or an area.
  • the size of a light valve (or 'sub-pixel') may be a length thereof and the comparable size of the multibeam element 116 may also be a length of the multibeam element 116.
  • size may refer to an area such that an area of the multibeam element 116 may be comparable to an area of the light valve (or 'sub-pixel').
  • the size of the multibeam element 116 is comparable to the light valve size such that the multibeam element size is between about fifty percent (50%) and about two hundred percent (200%) of the sub-pixel size.
  • the multibeam element size s may be given by equation (2) as
  • the multibeam element size is equal to or greater than about sixty percent (60%) of the sub-pixel size, or equal to or greater than about seventy percent (70%) of the sub-pixel size, or equal to or greater than about eighty percent (80%) of the sub-pixel size, or equal to or greater than about ninety percent (90%) of the subpixel size.
  • the multibeam element is equal to or less than about one hundred eighty percent (180%) of the sub-pixel size, or equal to or less than about one hundred sixty percent (160%) of the sub-pixel size, or equal to or less than about one hundred forty percent (140%) of the sub-pixel size, or equal to or less than about one hundred twenty percent (120%) of the sub-pixel size.
  • the multibeam element size may be between about seventy-five percent (75%) and about one hundred fifty (150%), inclusive, of the sub-pixel size.
  • the multibeam element 116 may be comparable in size to the sub-pixel where the multibeam element size is between about one hundred twenty-five percent (125%) and about eighty-five percent (85%), inclusive, of the sub-pixel size.
  • the comparable sizes of the multibeam element 116 and the light valve may be chosen to reduce, or in some embodiments to minimize, dark zones between views of the multiview display, while at the same time reducing, or in some embodiments minimizing, an overlap between views of the multiview display.
  • Figures 7-9 further illustrate the light valve array 120 positioned above the multibeam backlight 110.
  • the light valve array 120 so positioned, is configured to modulate the plurality of coupled-out light beams 112.
  • the light valve array 120 is partially cut-away to allow visualization of the light guide 114 and the multibeam element 116 underlying the light valve array 120.
  • different ones of the coupled-out light beams 112 having different principal angular directions pass through and may be modulated by respective different ones of the light valves in the light valve array 120.
  • a light valve of the light valve array 120 corresponds to a sub-pixel, and a set of the light valves corresponds to a multiview pixel of the multiview display 100.
  • a different set of light valves of the light valve array 120 is configured to receive and modulate the coupled-out light beams 112 from different ones of the multibeam elements 116, i.e., there is one unique set of light valves for each multibeam element 116, as illustrated in Figures 7-9.
  • a first light valve set 120a is configured to receive and modulate the coupled-out light beams 112 from a first multibeam element 116a
  • a second light valve set 120b is configured to receive and modulate the coupled-out light beams 112 from a second multibeam element 116b.
  • each of the light valve sets (e.g., the first and second light valve sets 120a, 120b) in the light valve array 120 corresponds, respectively, to a different multiview pixel 108 (see Figure 8), with individual light valves of the light valve sets 120a, 120b corresponding to the sub-pixels of the respective different multiview pixels 108, as illustrated in Figures 7-9.
  • a relationship between the multibeam elements 116 and corresponding multiview pixels 108 may be a one-to-one relationship. That is, there may be an equal number of multiview pixels 108 and multibeam elements 116.
  • the one-to-one relationship is illustrated by way of example, where each multiview pixel 108 (comprising a different set of light valves or sub-pixels) is illustrated as being surrounded by a dashed line. In other embodiments (not illustrated), the number of multiview pixels and multibeam elements may differ from one another.
  • an inter-element distance (e.g., center-to-center distance) between a pair of adjacent multibeam elements 116 may be equal to an interpixel distance (e.g., a center-to-center distance) between a corresponding adjacent pair of multiview pixels 108, e.g., represented by light valve sets.
  • an interpixel distance e.g., a center-to-center distance
  • a center-to-center distance d between the first multibeam element 116a and the second multibeam element 116b is substantially equal to a center-to-center distance D between the first light valve set 120a and the second light valve set 120b.
  • the relative center-to-center distances of pairs of multibeam elements 116 and corresponding light valve sets may differ, e.g., the multibeam elements 116 may have an inter-element spacing (i.e., center-to-center distance d) that is one of greater than or less than a spacing (i.e., center-to-center distance D) between light valve sets representing multiview pixels.
  • the multibeam elements 116 may have an inter-element spacing (i.e., center-to-center distance d) that is one of greater than or less than a spacing (i.e., center-to-center distance D) between light valve sets representing multiview pixels.
  • a shape of the multibeam element 116 is analogous to a shape of the multiview pixel 108 or equivalently, a shape of a set (or 'sub-array') of the light valves in the light valve array 120 corresponding to the multiview pixel 108.
  • the multibeam element 116 may have a substantially square shape and the multiview pixel 108 (or an arrangement of a corresponding set of light valves) may be substantially square.
  • the multibeam element 116 may have a substantially rectangular shape, i.e., may have a length or longitudinal dimension that is greater than a width or transverse dimension.
  • the multiview pixel 108 corresponding to the multibeam element 116 may have a substantially analogous rectangular shape.
  • Figure 8 illustrates a top or plan view of square-shaped multibeam elements 116 and corresponding square-shaped multiview pixels comprising square sets of light valves, e.g., outlined by dashed lines.
  • the multibeam elements 116 and the corresponding multiview pixels have various shapes including or at least approximated by, but not limited to, a triangular shape, a hexagonal shape, and a circular shape.
  • the multibeam elements 116 may comprise any of a number of different structures configured to couple out a portion of the guided light 104.
  • the different structures may include, but are not limited to, diffraction gratings, micro-reflective elements, micro-refractive elements, or various combinations thereof.
  • the multibeam element 116 comprising a diffraction grating is configured to diffractively couple out of the light guide 114 a portion of the guided light 104 as the plurality of coupled-out light beams 112 having the different principal angular directions.
  • the multibeam element 116 comprising a micro-reflective element is configured to reflectively couple out of the light guide 114 the guided light portion as the plurality of coupled-out light beams 112.
  • the multibeam element 116 comprising a micro-refractive element is configured to couple out of the light guide 114 the guided light portion as the plurality of coupled-out light beams 112 by or using refraction (i.e., refractively couple out the guided light portion).
  • Figure 10 illustrates a cross sectional view of a portion of a multibeam backlight 110 including a multibeam element 116 in an example, according to an embodiment consistent with the principles described herein.
  • Figure 11 illustrates a cross sectional view of a portion of a multibeam backlight 110 including a multibeam element 116 in an example, according to another embodiment consistent with the principles described herein.
  • Figures 10-11 illustrate the multibeam element 116 of the multibeam backlight 110 comprising a diffraction grating within the light guide 114.
  • the diffraction grating is configured to diffractively couple out of the light guide 114 a portion of the guided light 104 as the plurality of coupled-out light beams 112.
  • the diffraction grating comprises a plurality of diffractive features spaced apart from one another by a diffractive feature spacing or a diffractive feature or grating pitch (i.e., the pitch or spacing of the diffractive features in the diffractive grating).
  • the spacing or pitch is configured to provide the diffractive coupling out of the guided light portion.
  • the spacing or grating pitch of the diffractive features in the diffraction grating may be sub -wavelength (i.e., less than a wavelength of the guided light 104).
  • the diffraction grating of the multibeam element 116 may be located at or adjacent to a surface of the light guide 114.
  • the diffraction grating may be at or adjacent to the first surface 114' of the light guide 114, as illustrated in Figure 10.
  • the diffraction grating located at light guide first surface 114' may be a transmission mode diffraction grating configured to diffractively couple out the guided light portion as the coupled-out light beams 112 through the first surface 114'.
  • the diffraction grating may be located at or adjacent to the second surface 114" of the light guide 114.
  • the diffraction grating When located at the second surface 114", the diffraction grating may be a reflection mode diffraction grating. As a reflection mode diffraction grating, the diffraction grating is configured to both diffract the guided light portion and reflect the diffracted guided light portion toward the first surface 114' to exit through the first surface 114' as the diffractively coupled-out light beams 112. In other embodiments (not illustrated), the diffraction grating may be located between the surfaces of the light guide 114, e.g., as one or both of a transmission mode diffraction grating and a reflection mode diffraction grating.
  • the principal angular directions of the coupled-out light beams 112 may include an effect of refraction due to the coupled-out light beams 112 exiting the light guide 114 at a light guide surface.
  • Figure 11 illustrates refraction (i.e., bending) of the coupled-out light beams 112 due to a change in refractive index as the coupled-out light beams 112 exit through the first surface 114', by way of example and not limitation. Also see Figures 12 and 13, described below.
  • the diffractive features of the diffraction grating may comprise one or both of grooves and ridges that are spaced apart from one another.
  • the grooves or the ridges may comprise a material of the light guide 114, e.g., may be formed in a surface of the light guide 114.
  • the grooves or the ridges may be formed from a material other than the light guide material, e.g., a film or a layer of another material on a surface of the light guide 114.
  • the diffraction grating of the multibeam element 116 is a uniform diffraction grating in which the diffractive feature spacing is substantially constant or unvarying throughout the diffraction grating.
  • the diffraction grating is a chirped diffraction grating.
  • the 'chirped' diffraction grating is a diffraction grating exhibiting or having a diffraction spacing of the diffractive features (i.e., the grating pitch) that varies across an extent or length of the chirped diffraction grating.
  • the chirped diffraction grating may have or exhibit a chirp of the diffractive feature spacing that varies linearly with distance.
  • the chirped diffraction grating is a 'linearly chirped' diffraction grating, by definition.
  • the chirped diffraction grating of the multibeam element 116 may exhibit a non-linear chirp of the diffractive feature spacing.
  • Various non-linear chirps may be used including, but not limited to, an exponential chirp, a logarithmic chirp or a chirp that varies in another, substantially non-uniform or random but still monotonic manner.
  • Non-monotonic chirps such as, but not limited to, a sinusoidal chirp or a triangle or sawtooth chirp, may also be employed. Combinations of any of these types of chirps may also be employed.
  • Figure 12 illustrates a cross sectional view of a portion of a multibeam backlight 110 including a multibeam element 116 in an example, according to another embodiment consistent with the principles described herein.
  • Figure 13 illustrates a cross sectional view of a portion of a multibeam backlight 110 including a multibeam element 116 in an example, according to another embodiment consistent with the principles described herein.
  • Figures 12 and 13 illustrate various embodiments of the multibeam element 116 comprising a micro-reflective element.
  • Micro-reflective elements used as or in the multibeam element 116 may include, but are not limited to, a reflector that employs a reflective material or layer thereof (e.g., a reflective metal) or a reflector based on total internal reflection (TIR).
  • the multibeam element 116 comprising the micro-reflective element may be located at or adjacent to a surface (e.g., the second surface 114") of the light guide 114.
  • the micro- reflective element may be located within the light guide 114 between the first and second surfaces 114', 114".
  • Figure 12 illustrates the multibeam element 116 comprising a micro-reflective element having reflective facets, for example, that may be similar to facets of a prism, (e.g., a 'prismatic' micro-reflective element) located adjacent to the second surface 114" of the light guide 114.
  • the facets of the illustrated prismatic micro- reflective element are configured to reflect (i.e., reflectively couple) the portion of the guided light 104 out of the light guide 114.
  • the facets may be slanted or tilted (i.e., have a tilt angle) relative to a propagation direction of the guided light 104 to reflect the guided light portion out of light guide 114, for example.
  • the facets may be formed using a reflective material within the light guide 114 (e.g., as illustrated in Figure 12) or may be surfaces of a prismatic cavity in the second surface 114", according to various embodiments.
  • a prismatic cavity either a refractive index change at the cavity surfaces may provide reflection (e.g., TIR reflection) or the cavity surfaces that form the facets may be coated with a reflective material to provide reflection, in some embodiments.
  • Figure 13 illustrates the multibeam element 116 comprising a micro-reflective element having a curved surface such as, but not limited to, a semi -spherical micro-reflective element.
  • the curved surface of the micro-reflective element may be substantially smooth.
  • a specific surface curve of the micro-reflective element may be configured to reflect the guided light portion in different directions depending on a point of incidence on the curved surface with which the guided light 104 makes contact, for example.
  • the guided light portion that is reflectively coupled out of the light guide 114 exits or is emitted from the first surface 114'.
  • the micro-reflective element in Figure 13 may be either a reflective material within the light guide 114 or a cavity (e.g., a semi-circular cavity) formed in the second surface 114", as illustrated in Figure 13 by way of example and not limitation.
  • Figures 12 and 13 also illustrate the guided light 104 having two propagation directions indicated by arrows 103, 103', by way of example and not limitation. Using two propagation directions of the guided light 104 may facilitate providing the plurality of coupled-out light beams 112 with substantially symmetrical distribution of principal angular directions, for example.
  • Figure 14 illustrates a cross sectional view of a portion of a multibeam backlight 110 including a multibeam element 116 in an example, according to another embodiment consistent with the principles described herein.
  • Figure 14 illustrates a multibeam element 116 comprising a micro-refractive element.
  • the micro-refractive element is configured to refractively couple out a portion of the guided light 104 from the light guide 114. That is, the micro- refractive element is configured to employ refraction (e.g., as opposed to diffraction or reflection) to couple out the guided light portion from the light guide 114 as the coupled- out light beams 112, as illustrated in Figure 14.
  • the micro-refractive element may have various shapes including, but not limited to, a semi -spherical shape, a rectangular shape or a prismatic shape (i.e., a shape having sloped facets). According to various embodiments, the micro-refractive element may extend or protrude out of a surface (e.g., the first surface 114') of the light guide 114, for example as illustrated, or may be a cavity in the surface (not illustrated). Further, the micro-refractive element may comprise a material of the light guide 114, in some embodiments. In other embodiments, the micro- refractive element may comprise another material adjacent to, and in some examples, in contact with the light guide surface.
  • the multibeam backlight 110 may further comprise a light source 118, in some embodiments.
  • the light source 118 is configured to provide the light to be guided within light guide 114 at a non-zero propagation angle.
  • the light source 118 may be located adjacent to an entrance surface or end (input end) of the light guide 114.
  • the light source 118 may comprise substantially any source of light (e.g., optical emitter), e.g., as provided above, including, but not limited to, one or more light emitting diodes (LEDs) or a laser (e.g., laser diode).
  • LEDs light emitting diodes
  • laser diode e.g., laser diode
  • the light source 118 may comprise an optical emitter configured produce a substantially monochromatic light having a narrowband spectrum denoted by a particular color.
  • the color of the monochromatic light may be a primary color of a particular color space or color model (e.g., a red-green-blue (RGB) color model).
  • the light source 118 may be a substantially broadband light source configured to provide substantially broadband or polychromatic light.
  • the light source 118 may provide white light.
  • the light source 118 may comprise a plurality of different optical emitters configured to provide different colors of light. The different optical emitters may be configured to provide light having different, color-specific, non-zero propagation angles of the guided light 104 corresponding to each of the different colors of light.
  • the light source 118 may further comprise a collimator.
  • the collimator may be configured to receive substantially uncollimated light from one or more of the optical emitters of the light source 118.
  • the collimator is further configured to convert the substantially uncollimated light into collimated light.
  • the collimator may provide collimated light having the non-zero propagation angle and being collimated according to a predetermined collimation factor c, according to some embodiments.
  • the collimator may be configured to provide the collimated light having one or both of different, color-specific, non-zero propagation angles and having different color-specific collimation factors.
  • FIG. 15 illustrates a schematic drawing of an example of a multiview display 1500, according to an embodiment consistent with the principles described herein.
  • the multiview display 1500 may include a light guide 1502, which may be similar in structure and function to light guide 314 ( Figures 3 and 4).
  • the light guide 1502 may have an aperture layer 1504 within the light guide 1502.
  • the aperture layer 1504 may be similar in structure and function to aperture layer 332 ( Figure 3).
  • the aperture layer 1504 may include a plurality of apertures 1506, which may be similar in structure and function to aperture 334 ( Figure 4).
  • the apertures 1506 may be configured to reduce an angular spread of guided light in a horizontal direction parallel to a guiding surface of the light guide 1502.
  • the multiview display 1500 may further include a multibeam element array 1508.
  • the multibeam element array 1508 may include multibeam elements 1510 arranged along the light guide 1502. Each multibeam element 1510 of the multibeam element array 1508 may be aligned with a corresponding aperture 1506 of the aperture layer 1504. Each multibeam element 1510 of the multibeam element array 1508 may be configured to scatter out a portion of the guided light received from the aperture 1506 as directional light beams having directions corresponding to view directions of the multi view display 1500.
  • the multiview display 1500 may further include a light valve array 1512, which may be similar in structure and function to light valve array 120.
  • the light valve array 1512 may be configured to modulate the directional light beams and provide a multiview image displayed by the multiview display 1500.
  • the multiview display 1500 may optionally further include a light source 1514, which may be similar in structure and function to light source 118, that may be configured to provide the light to be guided as the guided light within the light guide 1502.
  • a light source 1514 which may be similar in structure and function to light source 118, that may be configured to provide the light to be guided as the guided light within the light guide 1502.
  • the aperture layer 1504 may include pairs of lightblocking elements, such as light-blocking elements 502A, 502B ( Figures 5 and 6).
  • the light-blocking elements of the pair of light-blocking elements may be spaced apart from each other in at least one direction, such as the horizontal direction parallel to a guiding surface of the light guide 1502.
  • the apertures 1506 may be defined as a space between the light-blocking elements.
  • the pairs of light-blocking elements may include parallel strips that extend along a length of the light guide 1502 and along rows of multibeam elements 1510 of the multibeam element array 1508.
  • the aperture layer 1504 may further include another light-blocking element, such as other light-blocking element 602 ( Figure 6).
  • the other light-blocking element may span between individual pairs of light-blocking elements and may define a length of the aperture 1506.
  • the multibeam elements 1510 may comprise one or more of: a diffraction grating configured to diffractively scatter out the guided light portion as the directional light beams, a micro-reflective element configured to reflectively scatter out the guided light portion as the directional light beams, and a micro-refractive element configured to refractively scatter out the guided light portion as the directional light beams.
  • a size of a multibeam element 1510 of the multibeam element array 1508 may be between one quarter and two times a size of a light valve of the light valve array 1512.
  • Figure 16 illustrates a flow chart of an example of a method 1600 of backlight operation, according to an embodiment consistent with the principles described herein.
  • the method 1600 of backlight operation may include guiding 1602 light in a light guide, such as light guide 314 or light guide 1502, as guided light, such as guided light 104, having a first angular spread.
  • the method 1600 of backlight operation may further include reducing 1604 an angular spread of the guided light using apertures, such as aperture 334, aperture 334’, apertures 334”, or aperture 1506, of an aperture layer, such as aperture layer 332 or aperture layer 1504, to provide guided light having a second angular spread.
  • the first angular spread and the second angular spread may be in a direction parallel to a guiding surface of the light guide.
  • the method 1600 of backlight operation may further include scattering 1606 the guided light having the second angular spread out of the light guide as emitted light using a plurality of scattering elements, such as scattering elements 316.
  • a plurality of scattering elements such as scattering elements 316.
  • Each scattering element of the plurality of scattering elements may be aligned with a corresponding aperture of the aperture layer.
  • the alignment may be along a direction parallel to the guiding surface of the light guide and orthogonal to the direction of the first angular spread and the second angular spread, such that each scattering element may be downstream from a corresponding aperture.
  • the aperture layer may include a pair of lightblocking elements spaced apart from each other in the direction parallel to the guiding surface of the light guide.
  • Each aperture may be defined as a respective space between a respective pair of light-blocking elements.
  • the scattering elements may include multibeam elements configured to scatter out the guided light as the emitted light.
  • the emitted light may have a plurality of directional light beams with propagation directions corresponding to respective view directions of a multiview display.
  • the method of backlight operation may be a method of multiview backlight operation.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Planar Illumination Modules (AREA)

Abstract

L'invention concerne un rétroéclairage à collimation automatique qui peut comprendre un guide de lumière qui peut guider la lumière en tant que lumière guidée. Le rétroéclairage à collimation automatique peut comprendre une couche d'ouverture située à l'intérieur du guide de lumière. La couche d'ouverture peut comprendre une ouverture qui peut réduire un étalement angulaire de la lumière guidée qui passe à travers l'ouverture. L'étalement angulaire peut être réduit dans une direction horizontale parallèle à une surface de guidage du guide de lumière et perpendiculaire à une direction de propagation de la lumière guidée. Le rétroéclairage à collimation automatique peut comprendre un élément de diffusion aligné avec l'ouverture. L'élément de diffusion peut diffuser une partie de la lumière guidée reçue à partir de l'ouverture et ayant l'étalement angulaire réduit en tant que lumière émise du rétroéclairage à collimation automatique.
PCT/US2022/082101 2022-12-21 2022-12-21 Rétroéclairage à collimation automatique, affichage multivue et procédé WO2024136897A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040004417A (ko) * 1995-11-06 2004-01-13 세이코 엡슨 가부시키가이샤 조명 장치 및 그것을 이용한 액정 표시 장치 및 전자 기기
US20120087007A1 (en) * 2009-06-17 2012-04-12 Takayoshi Suganuma Light-guiding substrate and optical system provided with same
US20200033621A1 (en) * 2017-04-08 2020-01-30 Leia Inc. Multiview backlight, mode-switchable backlight, and 2d/3d mode-switchable display
US20210223454A1 (en) * 2018-10-15 2021-07-22 Leia Inc. Backlight, multiview display and method having a grating spreader
US20220050239A1 (en) * 2019-04-30 2022-02-17 Leia Inc. Light source, multiview backlight, and method with a bifurcated emission pattern

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040004417A (ko) * 1995-11-06 2004-01-13 세이코 엡슨 가부시키가이샤 조명 장치 및 그것을 이용한 액정 표시 장치 및 전자 기기
US20120087007A1 (en) * 2009-06-17 2012-04-12 Takayoshi Suganuma Light-guiding substrate and optical system provided with same
US20200033621A1 (en) * 2017-04-08 2020-01-30 Leia Inc. Multiview backlight, mode-switchable backlight, and 2d/3d mode-switchable display
US20210223454A1 (en) * 2018-10-15 2021-07-22 Leia Inc. Backlight, multiview display and method having a grating spreader
US20220050239A1 (en) * 2019-04-30 2022-02-17 Leia Inc. Light source, multiview backlight, and method with a bifurcated emission pattern

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