PATENT DOCUMENT

Publication Number: US-11163157-B1
Application Number: US-201615264048-A
Country: US
Kind Code: B1

Title: Light field head-up display

Abstract:
A vehicle may have a light-field head-up display that produces a light-field output allowing a viewer in the vehicle to observe three-dimensional content. An array of light-field display units and corresponding lenses may be used to direct the light-field output towards the viewer. The head-up display may have a transmissive display such as a liquid crystal display or other display with an array of backlit pixels. The pixels may have subpixels of different colors and may have elongated shapes extending along a given dimension. Lenticular lenses in the transmissive display that overlap the pixels may extend along the given dimension. A directional backlight may be used to adjust the direction of the light-field output produced by a light-field display unit. The directional backlight may be adjusted to alternately provide light-field output to the left and right eyes of a viewer.

Claims:
What is claimed is: 
     
       1. A light-field head-up display that reflects light-field output off of a window in a vehicle towards a viewer at a viewer position in the vehicle, comprising:
 a light-field display unit that produces light-field output, wherein the light-field display unit has a transmissive display with an array of pixels and has a directional backlight that produces backlight in different directions in accordance with different respective settings; and 
 an optical system that provides the light-field output from the light-field display unit to the window of the vehicle so that the light-field output reflects towards the viewer position. 
 
     
     
       2. The light-field head-up display defined in  claim 1  wherein the light-field head-up display directs the light-field output in a first direction when the directional backlight is operated with a first of the settings and in a second direction that is different than the first direction when the directional backlight is operated with a second of the settings. 
     
     
       3. The light-field head-up display defined in  claim 2  wherein the viewer has left and right eyes at respective left and right eye positions and wherein the light-field output is directed towards a region that overlaps the left eye position and not the right eye position when the directional backlight is operated with the first of the settings and a region that overlaps the right eye position and not the left eye position when the directional backlight is operated with the second of the settings. 
     
     
       4. The light-field head-up display defined in  claim 3  wherein the light-field display unit comprises lenses each of which overlaps a different respective set of the pixels. 
     
     
       5. The light-field head-up display defined in  claim 4  wherein the array of pixels includes rows and columns of pixels extending respectively along each of two perpendicular dimensions, wherein the pixels in the array of pixels each include red, green and blue subpixels, wherein each pixel has an elongated shape that extends along a given one of the two perpendicular dimensions, and wherein the lenses comprise elongated lenticular lenses that extend along the given one of the two perpendicular dimensions. 
     
     
       6. The light-field head-up display defined in  claim 1  wherein the light-field display unit comprises lenticular lenses that overlap respective sets of the pixels. 
     
     
       7. The light-field head-up display defined in  claim 1  wherein the optical system comprises mirror lenses. 
     
     
       8. A light-field head-up display that reflects light-field output off of a window in a vehicle towards a viewer at a viewer position in the vehicle, comprising:
 a light-field display unit that produces light-field output, wherein the light-field display unit has a transmissive display unit with an array of pixels overlapped by lenticular lenses and has a directional backlight that is adjustable to produce backlight illumination for the transmissive display unit in different directions; and 
 an optical system that provides the light-field output from the light-field display to the window of the vehicle so that the light-field output reflects towards the viewer position. 
 
     
     
       9. The light-field head-up display defined in  claim 8  wherein the array of pixels includes rows and columns of pixels extending respectively along each of two perpendicular dimensions, wherein the pixels in the array of pixels each include red, green and blue subpixels, wherein each pixel has an elongated shape that extends along a given of the two perpendicular dimensions, and wherein the lenticular lenses extend along the given one of the two perpendicular dimensions. 
     
     
       10. The light-field head-up display defined in  claim 9  wherein the directional backlight is alternately operated to produce backlight illumination in a first of the different directions and a second of the different directions.

Description:
This application claims the benefit of U.S. provisional patent application No. 62/221,561, filed Sep. 21, 2015, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to displays, and, more particularly, to head-up displays. 
     Vehicles such as automobiles are sometimes provided with head-up displays. Head-up displays project images onto the windshield of a vehicle. A driver of the vehicle can view the projected images while driving. Head-up displays are typically used to display vehicle status information such as speedometer information. Head-up displays allow information to be safely displayed for a driver without requiring the driver to look away from the road ahead. 
     To maximize the usefulness of head-up displays in vehicular environments, it would be desirable to be able to enhance the ability of a head-up display to display information for the occupants of a vehicle. 
     SUMMARY 
     A vehicle may have windows. A head-up display may produce output that reflects off of one of the windows towards a viewer such as a driver or other occupant in the vehicle. The head-up display may be a light-field head up display that produces a light-field output allowing the viewer to observe three-dimensional content on the head-up display. 
     An array of light-field display units and corresponding lenses may be used to direct the light-field output towards the viewer. The lenses may direct overlapping light-field output from the display units towards the viewer, thereby creating an enlarged seamless light-field viewing area on the window of the vehicle. 
     The head-up display may have a transmissive display such as a liquid crystal display or other display with an array of backlit pixels. The pixels may include subpixels of different colors. Each pixel may have an elongated shape and may extend along a given dimension. Lenticular lenses in the transmissive display that overlap the pixels may extend along the given dimension in parallel with the elongated pixels. 
     A directional backlight may be used to adjust the direction of the light-field output produced by the light-field display. The directional backlight may be adjusted to alternately provide light-field output to the left and right eyes of the viewer or to alternately provide the light-field output to two different viewers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an illustrative vehicle with a head-up display in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative vehicle or other system with a head-up display in accordance with an embodiment. 
         FIG. 3  is a side view of an illustrative head-up display in a vehicle in accordance with an embodiment. 
         FIG. 4  is a perspective view of a display with a lenticular lens array for use in a light field head up display in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of a portion of the display of  FIG. 4  in accordance with an embodiment. 
         FIG. 6  is a top view of an illustrative viewer and an associated viewing region produced by a light field head-up display in accordance with an embodiment. 
         FIG. 7  is a top view of an illustrative head-up display with an array of lenses in accordance with an embodiment. 
         FIG. 8  is a top view of an illustrative viewer and an associated head-up display viewing region (viewing box) having subregions aligned with the left and right eyes of the viewer in accordance with an embodiment. 
         FIGS. 9 and 10  are diagrams of illustrative directional backlights that may be used in head-up displays in accordance with an embodiment. 
         FIG. 11  is a top view of an illustrative array of pixels for a light-field display unit in a head-up display in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Systems such as vehicles and other systems may incorporate displays. As an example, a vehicle may have a head-up display that displays vehicle status information such as vehicle speed, direction, and location, fuel gauge information, battery charge level information, status information on vehicle operations such as headlight status, heating and air-conditioner status, seatbelt status, headlight status, media playback information (e.g., current radio station and track information), messages, alerts, and other information. 
     A side view of an illustrative vehicle of the type that may be provided with a head-up display is shown in  FIG. 1 . As shown in  FIG. 1 , vehicle  10  may include a body such as body  12 . Body  12  may have body panels and other structures that are mounted on a chassis. Interior components in vehicle  10  such as seating for a driver and other vehicle occupants may be supported by the chassis. External components such as wheels  18  may also be mounted to the chassis. The structures that make up body  12  may include metal structures, structures formed from fiber-composite materials such as carbon-fiber materials and fiberglass, plastic, and other materials. Vehicle  10  may include lights  16 . 
     Vehicle body  12  may include doors. Windows  14  may be formed at the front and rear of vehicle  10  in openings in body  12  and may be formed within the doors or other portions of the body  12  of vehicle  10 . As shown in  FIG. 1 , for example, vehicle  10  may have a front window such as front window  14 F that faces the front of vehicle, rear facing windows such as rear window  14 R, and side windows such as windows mounted within the doors of vehicle  10  (see, e.g., side windows  14 D). Windows  14  may be formed from glass (e.g., glass laminated with polymer layers), plastics such as polycarbonate, or other clear materials. 
     There may be one or more head-up displays in vehicle  10 . Each head-up display may display images by reflecting light off of the interior surface of a respective one of windows  14 . To provide the driver of vehicle  10  with head-up display information, a head-up display may be used to reflect light from front window  14 F. Head-up displays may also be associated with rear window  14 R and side windows  14 D. The driver and other occupants of vehicle  10  such as front and rear seat passengers may, if desired, be provided with head-up displays. Illustrative configurations in which a head-up display in vehicle  10  is associated with front window  14 F are sometimes described herein as an example. If desired, head-up displays may be provided in other windows  14 . The viewer of a head-up display may be a vehicle driver, front-seat passenger, or rear-seat passenger. Configurations in which the viewer of the head-up display is a driver may sometimes be described herein as an example. 
     A schematic diagram of illustrative circuitry that may be used in operating vehicle  10  is shown in  FIG. 2 . As shown in  FIG. 2 , vehicle  10  may include control circuitry  20 . Control circuitry  20  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  20  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, electronic control units, etc. 
     Vehicle  10  may include input-output devices  22  that allow data to be supplied to vehicle  10  and that allow data to be provided from vehicle  10  to external systems. Input-output devices  22  may include sensors  30  for gathering information on the operating environment of vehicle  10 . Sensors  30  may include light-based sensors, wireless sensors such as radar sensors, ultrasonic sensors, proximity sensors, range-finding sensors, ambient light sensors, strain gauges, parking sensors, cruise control sensors, accelerometers, touch sensors, magnetic sensors such as electronic compass sensors, temperature sensors, rain sensors and other moisture sensors, force sensors, pressure sensors (e.g., altimeters), speedometers, odometers, tachometers, battery charge gauges, fuel gauges, circuits for determining the status of headlights and other lighting, seat belt sensors, door lock sensors, fuel door status, trunk status (open or closed), window status (up or down), and other components for making measurements on the environment surrounding vehicle  10  and the operating status of vehicle  10 . 
     As shown in  FIG. 2 , input-output devices  22  may include user input-output devices  26 . Devices  26  may be used to gather input from vehicle occupants and may be used in providing output to vehicle occupants. Devices  26  may include buttons, joysticks, steering wheels, shift levels and/or buttons, foot-actuated controllers (e.g., a throttle pedal, a brake pedal, a clutch pedal, etc.), touch pads, keypads, keyboards, motion sensors, microphones, cameras (digital image sensors), and other devices for gathering user input. Output devices in devices  26  may also include circuitry for generating audio output such as speakers, tone generators, and vibrators and circuitry for generating visible output. 
     Input-output devices  22  may include one or more displays for displaying visual information for a viewer (e.g., a driver or other vehicle occupant). For example, input-output devices  22  may include head-up display  28 . Head-up display  28  may include a projector (e.g., a projector based on a micromirror array), liquid crystal display, organic light-emitting diode display, or other display unit for generating images for a viewer and an optical system for directing the images towards the viewer. The optical system may include a lens to project images from the display onto front window  14 F so that the viewer (e.g., the driver of the vehicle) can view both head-up display content reflected from the front window and real-life objects that are visible through the front window. 
     Multiple display units and an associated array of lenses may be used to expand the viewable area of the head-up display. A camera (e.g., one or more digital image sensor integrated circuits and associated lens structures and/or one or more other light-based sensors or other sensors) may be used to track the position of the viewer&#39;s head and eyes. Using this tracking information, the viewing zone for the display (i.e., the head position region from which head-up display content is viewable) can be moved to accommodate movement of the viewer. A subset of the viewing zone that is aligned with the viewer&#39;s eyes may be provided with content while no content is being provided to portions of the viewing zone that are not being actively used, thereby reducing the display content processing burden on the head-up display. Display resolution may be enhanced by using time-division multiplexing schemes and directional backlights to direct the output of the head-up display alternately into subsets of the viewing zone that are aligned respectively with the left and right eyes of the viewer. 
     Wireless circuitry  32  may include radio-frequency transceiver circuitry and antennas for transmitting and receiving wireless signals. The signals may include, for example, short-range signals such as wireless local area network signals (WiFi® and Bluetooth® signals) and long-range signals (e.g., cellular telephone signals and other signals at frequencies of 700 MHz to 2700 MHz and/or other suitable frequencies). Wireless information may be shared with nearby vehicles, sensors and beacons embedded along a roadway, satellites, cellular telephone networks, cellular telephones, wristwatches, and other wireless devices associated with a driver and passengers in vehicle  10 , etc. Wireless information that is received by circuitry  32  may include traffic information, weather information, information on the status of nearby vehicles (e.g., direction of motion, acceleration/deceleration, brake status (braking due to application of brakes by a driver or not braking), throttle status (applied or not applied), temperature information, road condition information (as measured by sensors in vehicles and/or external sensors), etc. 
     Vehicle controls  34  may include control circuitry, actuators, and other systems for controlling vehicle operation. Vehicle controls  34  may include systems for steering, braking (manual brakes, emergency brakes, power-assisted brakes, drum brakes, disc brakes, regenerative brakes that use drive motors or other systems to recover energy and convert the kinetic energy of vehicle  10  into electrical energy stored in capacitors and/or batteries or that use other techniques for storing recovered energy, or other braking systems), accelerating, shifting gears, adjusting interior and exterior lights, adjusting infotainment functions, controlling satellite navigation system operation, adjusting airbags, seatbelts, and other safety devices, controlling audio output, controlling electronic windows, door locks, the opening and closing of doors and hatches, windshield wipers, defrosters, and other climate controls, and systems for controlling and adjusting other operations during the operating of vehicle  10 . 
     Using information from sensors  30 , user input and other input from devices  26 , and/or information received wirelessly from remote sources via wireless circuitry  32 , vehicle  10  may determine actions to take in supplying output and otherwise controlling the operation of vehicle  10 . As an example, control circuitry  20  may determine that head-up display  28  should display vehicle status information to a viewer. The vehicle status information may include odometer information, speedometer information, tachometer information, fuel gauge or battery charge gauge information, seatbelt status information, headlight status information, fuel door status, information on the status of doors and windows in vehicle  10 , and other vehicle operating status information. Control circuitry  20  may also display augmented reality information on display  28  for the viewer. For example, a warning sign may be placed in the field of view of the driver of vehicle  10  to alert the driver when a potential obstruction in the road is detected, to inform the driver when another vehicle is approaching vehicle  10  on a collision course, to inform the driver of poor upcoming road conditions or weather, etc. Augmented reality information may also include highlight regions to help a driver identify pedestrians or unexpected driving conditions. Public service announcements, driving tips, navigation information (maps, driving directions, points of interest, etc.) and other information may also be displayed. 
     If desired, head-up display  28  may be a light-field head up display. By producing a light field with specified light ray angular orientations as well as specified light ray intensities, the light-field head-up display can create an impression of three-dimensionality and depth in displayed content. As with a real-life three-dimensional object, the appearance of displayed content will vary as the position of the viewer shifts within vehicle  10 . In configurations in which head-up display  28  is a light field display having three-dimensional display capabilities, the head-up content that is displayed may have the appearance of being located within the environment surrounding vehicle  10 . For example, a highlight region for helping a driver identify the location of a pedestrian may appear to surround the pedestrian, an icon alerting the driver to a pothole or other road obstruction may visually appear to be a three-dimensional object located adjacent to the pothole, etc. 
     A side view an illustrative head-up display is shown in  FIG. 3 . As shown in  FIG. 3 , head-up display  28  may include one or more display units such as display unit  40  and one or more lenses forming an optical system such as optical system  58 . Display unit  40  may be a light-field display unit based on a liquid crystal display, organic light-emitting diode display, cathode ray tube, plasma display, projector display (e.g., a projector based on an array of micromirrors), or other suitable type of display. Light-field display unit  40  may generate a light-field associated with three-dimensional content to be displayed to viewer  68 . Optical system  58  may be used to present the light-field output from light-field display unit to viewer  68 . For example, optical system  58  may direct light-field output from display unit  40  to inner surface  64  of front window  14 F (or other suitable windows in vehicle  10 ). Reflected light  66  may be viewed by a viewer such as viewer  68  who is looking through window  14 F in direction  70 . Viewer  68  may simultaneously view content from display unit  40  and objects external to vehicle  10  such as external object  80  by looking in direction  70 . 
     A digital image sensor or other sensor(s) such as camera  72  may be used to track the position of the viewer&#39;s head (head  74 ) and/or the viewer&#39;s eyes (eyes  76 ). Viewer tracking information may be used to restrict the amount of light-field output that is generated (e.g., so that only information that is viewable by viewer  68  is generated by display unit  40 ). Restricting the amount of light-field output that is generated may reduce the processing burden placed on control circuitry  20  when creating three-dimensional display output with head-up display  28 . 
     In the illustrative configuration of  FIG. 3 , light-field display unit  40  is a projector-based system that includes a light source such as light source  44  that produces light  48 . Light  48  is reflected from beamsplitter  46  as reflected light  50 . Reflected light  50  is directed towards the face of micromirror array  42 . Light  50  reflects from micromirror array  42  as light-field output  52 . The direction and intensity of the light rays in light-field output  52  are modulated by micromirror array  42  to produce a desired light field. The light field output of light-field display unit  40  (output  52 ) is provided to optical system  58 . Optical system  58  may include lenses such as mirror lenses  60  and  62  or other suitable optical components that direct light-field output  52  onto inner surface  64  of window  14 F. 
     Window  14 F is partially reflective, so a portion of the light that is directed toward surface  64  by optical system  58  reflects toward viewer  68  as reflected light-field output  66 . If desired, the optical properties of window  14 F (e.g., the curvature of window  14 F) may be taken into account when configuring lenses  62  and  60 , so the reflective surface of window  14 F may be considered to be part of optical system  58 . Optical system  58  of  FIG. 3  has multiple lenses that together form a multi-element lens. If desired, optical system  58  may contain an array of lenses each of which contains multiple mirror lens elements such as mirror lenses  60  and  62 . Each of the lenses in the array of lenses may contain two lens elements (e.g., each lens in the array may be a multi-element lens containing two or more lens elements such as lens elements  60  and  62  of  FIG. 3 ) or each of the lenses in the array of lenses may be a single-element lens. The use of an array of lenses may help extend the area of head-up display  28  that is viewable by viewer  68  without making head-up display  28  excessively large (i.e., excessively deep). 
     If desired, display unit  40  may contain a flat panel display structure such as illustrative flat-panel light-field display  40 D of  FIG. 4 . Display  40 D may be a liquid crystal display (e.g., a backlight liquid crystal display), an organic light-emitting diode display, or other suitable display. Display  40 D may have an array of pixels for generating output light. Lens structures such as elongated lenticular lenses  40 L of  FIG. 4  may be formed on the surface of display  40 D. Lenticular lenses  40 L may have curved (e.g., semicircular) profiles and may extend parallel to each other along one of the lateral dimensions of display  28 D. 
     As shown in the cross-sectional side view of illustrative flat-panel light-field display  40 D of  FIG. 4 , each lens  28 L may overlap multiple pixels  40 P in the array of pixels of display  40 D (i.e., multiple pixels  40 P extending in a dimension perpendicular to the longitudinal axis of lens  28 L). By selecting appropriate pixels  40 P, both the intensity I and angle A (with respect to display surface normal n) of emitted light rays such as light ray  52 ′ may be controlled. During operation, a pattern of pixels  40 P may therefore be illuminated to create a desired light field at the output of display  40 D. Because the light field includes angle-controlled and intensity controlled light rays, three-dimensional content may be displayed for viewer  68 . Any suitable number of pixels  40 P may extend across the width of each lens  28 L (e.g., 30 pixels  40 P in a scenario in which display  40  is capable of presenting  30  different views to a viewer, more than 30 pixels, or fewer than 30 pixels). 
     In configurations of the type shown in  FIGS. 4 and 5  in which lenticular lenses  40 L are provided on display  40 D, the displayed content may exhibit three-dimensionality as the viewer moves back and forth horizontally, but will not exhibit three-dimensional behavior in the vertical dimension. If desired, a two-dimensional array of microlenses (e.g., circular microlenses) may be used in place of lenticular lenses  40 L to allow display unit  40  to produce a light field that supports three dimensionality in both horizontal and vertical directions. When an array of microlenses is used, each microlens may overlap a respective two-dimensional array of pixels  40 P. The illustrative arrangement of  FIGS. 4 and 5  allows a relatively high resolution to be maintained for displayed content while minimizing the number of pixels  40 P. 
     Another way in which to maintain a high resolution without requiring an excessive number of pixels  40 P in display  40 D involves restricting the size of the region in which light field output  52  is viewable. This region, which may sometimes be referred to as the viewing box or viewing region for display  28 , may be about 150 mm in width (e.g. the size of a viewer&#39;s head) or other suitable size. Control circuitry  20  may use camera  72  to track the position of head  74  and/or eyes  76  of viewer  68 . As the viewer&#39;s position shifts within vehicle  10 , the output of display  28  may be adjusted so that the direction of output light  52  is adjusted and the location of the viewing box shifts accordingly. In this way, the viewer&#39;s head and eyes may remain centered within the viewing box, even as the position of the viewer&#39;s head and eyes moves. 
       FIG. 6  shows how viewer  68  may initially be positioned in location  68 - 1  in alignment with viewing box  52 B- 1  (i.e., light-field output  52  is directed towards the viewing region associated with box  52 - 1 ). In this position, the viewer&#39;s left eye  76 - 1  and right eye  76 - 2  both receive light-field output  52  in viewing box  52 B- 1 , because viewing box  52 B- 1  overlaps left eye  76 - 1  and right eye  76 - 2 . As viewer  68  moves to position  68 - 2 , head-up display  28  may steer light-field output  52  so that the viewing box moves to position  52 B- 2  (e.g., light-field  52  may be steered using a directional backlight). This type of arrangement avoids the need to create an overly large viewing box (which would require a larger display and/or lowered display resolution). 
     The viewable area of display  28  may also be extended by using an array of lenses (i.e., an array of multi-element lenses such as lens  58  of  FIG. 3  or other suitable lenses) and an array of associated light-field display units  40  to present light field output  52  to viewer  68 . Each lens  58  may direct a light-field output from a respective light-field display unit  40  to the viewer in an overlapping fashion that creates a seamless enlarged viewing area. As shown in  FIG. 7 , multiple lenses  58  may be organized in a one-dimensional array (e.g., an array extending horizontally in front of viewer  68  in the example of  FIG. 7 ). Each lens  58  may be used to direct light-field output  52  from a respective one of light-field display units  40  to viewer  68  from a different respective light-field display  14 . Lenses  58  may be arranged so that the viewer&#39;s views of outputs  52  (virtual images  52 ′ of  FIG. 7 ) overlap and create seamless three-dimensional content over an extended head-up display area (e.g., lenses  58  may each be located less than a focal length away from a respective display unit  40 , so that the virtual image  52 ′ of each display unit  40  is larger than that display unit  40 ). 
     Display processing operations may be minimized by restricting light-field output  52  to subregions of viewing box  52 B that overlap the eyes of the viewer. As shown in  FIG. 8 , viewing box  52 B may contain multiple subregions  82 . Control circuitry  20  may direct display unit  40  to produce light-field output  52  that illuminates only those subregions  82  that overlap the eyes of the viewer. For example, light-field output  52  may be generated by display unit  40  that covers only subregion  52 B-L and subregion  52 B-R and not adjacent areas. The light-field output in subregion  52 B-L may overlap left eye  76 L and the light-field output in subregion  52 B-R may overlap right eye  76 R. Each light-field subregion in viewing box  52 B contains multiple views (e.g., 5 views, 15 views, 30 views, or other suitable number of views), but because the size of subregions  52 B-L and  52 B-R is only a subset of box  52 B, less light-field output needs to be generated and display processing operations are reduced accordingly. 
     Further reductions in display processing requirements may be obtained by using time-division multiplexing to alternate between the left and right eyes of viewer  68  (or between different occupants of vehicle  10 ). During odd time periods, for example, display  28  may produce light in viewing region  52 B-L, but not in region  52 B-R (or any other location overlapping viewer  68 ). During even time periods, the output of display  28  may be adjusted so that light is only produced in viewing region  52 B-R and not elsewhere in box  52 B. The rate at which output  52  alternates between region  52 B-L and  52 B-R may be selected to be faster than the response time of a human eye (e.g., 200 Hz or other suitable relatively fast frequency). As a result, viewer  68  will perceive constant flicker-free content in both eyes, even though display  28  is alternately producing content for left eye  76 L and right eye  76 R. 
     Output  52  may be directed into subregions of viewing box  52 B and may be caused to alternate between the viewer&#39;s left and right eyes using any suitable light-field output steering arrangement (e.g., an adjustable array of micromirrors, etc.). With one suitable arrangement, light-field display  40  may contain a transmissive display illuminated by a directional backlight with at least two different directional settings. The direction of the backlight illumination produced by the directional backlight and therefore the direction of light-field output  52  from display  40  may be adjusted by alternating the directional backlight between the two directional settings. 
     A configuration for light-field display  40  with an illustrative directional backlight unit that is based on a light guide structure is shown in  FIG. 9 . As shown in  FIG. 9 , directional backlight unit  40 B may include a light guide structure such as light guide structure  92 . Light guide structure  92  may be formed from clear plastic or other suitable material. Light may be emitted into the edges of light guide structure  92  by arrays of light-emitting diodes or other suitable light sources. The light-emitting diodes may include light-emitting diodes  90 L on the left of light guide structure  92  of  FIG. 9  and light-emitting diodes  90 R on the right of light guide structure  92  of  FIG. 9  (as an example). Protrusions, depressions, and/or other light-scattering structures  94  may be formed in light guide structure  92 . When a first light source such as an array of light-emitting diodes  90 L is used to emit light into light guide structure  92 , backlight is produced that travels through transmissive light-field display  40 D (e.g., a liquid crystal display) in direction  52 L. When a second light source such as an array of light-emitting diodes  90 R is used to emit light into light guide structure  92 , backlight is produced that travels through light-field display  40 D at a different direction (see, e.g., light  52 R, which travels at a non-zero angle with respect to light  52 L). The ability to alternate backlight unit  40 B between a first setting (light source  90 L activated and light source  90 R deactivated) and a second setting (light source  90 L deactivated and light source  90 R activated) to steer the backlight illumination produced by backlight unit  40 B allows light-field output  52  from light-field display  40  to be steered (e.g., to track head movements and/or to alternate between eyes  76 L and  76 R or other locations). 
     In the illustrative configuration of  FIG. 10 , directional backlight unit  40 B includes an array of light-generating elements  100  (e.g., light-emitting diodes, etc.). Backlight unit  40 B may provide backlight illumination for transmissive light-field display  40 D (e.g., a liquid crystal display). Lens  102  (e.g., an optical system with one or more lens elements) may be used to direct light from light-generating elements  100  through transmissive light-field display  40 D. By controlling which of light-generating elements  100  are activated, the light emitted from elements  100  and therefore the direction of light-field output from display  40 D may be steered (see, e.g., light-field output  52 R, which is directed in a first direction, and light-field output  52 L, which is directed in a second direction that different from the first direction). 
     It may be desirable to produce color images with display  28 . Color images may be produced by including colored pixels  40 P in light-field display  40 D. Colored pixels  40 P may include red subpixels, green subpixels, and blue subpixels or may include subpixels of other colors. In a light-emitting diode display, each pixel may have light-emitting diode subpixels that emit light of different colors. In a liquid crystal display, each subpixel may be associated with a color filter element of a different color (e.g., red, green, and blue color filter elements or color filter elements of other suitable colors). Other types of displays may use other types of colored subpixel elements. The use of light-emitting diodes of different colors in the subpixels of a light-emitting diode display and the use of color filter elements of different colors in the subpixels of a liquid crystal display in light-field display  40 D is merely illustrative. 
     A top view of light-field display  40 D showing an illustrative layout scheme that may be used for the array of pixels  40 P is shown in  FIG. 11 . As shown in  FIG. 11 , display  40 D may have an array of pixels  40 P organized in multiple rows R and columns C. Each lenticular lens  40 L overlaps a respective set of columns C (e.g., 30 columns, more than 30 columns, fewer than 30 columns, etc.). In the example of  FIG. 11 , each lens  40 L overlaps five columns C and numerous rows R. The pixels  40 P of each column C under a given lens  40 L may be used to produce a different view in light-field output  52 . 
     Each of pixels  40 P may contain a red subpixel R, green subpixel G, and blue subpixel B. Pixels  40 P may have elongated shapes that extend vertically along columns C. As a result, the red, green, and blue subpixels of each pixel  40 P in a given column are available for creating light output for the view associated with the given column, thereby maximizing display resolution. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20160913
Publication Date: 20211102
Grant Date: 20211102
Priority Date: 20150921
Inventors: 
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B30/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/0101", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B2027/0134", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/0101", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2380/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B2027/0118", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B30/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/0093", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2027/0147", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B2027/0134", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/0093", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2027/0134", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B2027/0147", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/0101", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B30/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2380/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B2027/0118", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 78372489