PATENT DOCUMENT

Publication Number: US-11448908-B1
Application Number: US-201916261408-A
Country: US
Kind Code: B1

Title: Displays with adjustable angles of view

Abstract:
A display may have display layers that form an array of pixels. An angle-of-view adjustment layer may overlap the display layers. The angle-of-view adjustment layer may include an array of adjustable louvers that move from a first position in which the angle of view of the display is restricted for a private viewing mode and a second position in which the angle of view of the display is not restricted for a normal viewing mode. The louvers may contain electrophoretic particles. The louvers may be tapered and may have a width at one end that is less than ten microns. The electrophoretic particles may form isolated clusters on a lower substrate in normal viewing mode to increase the transmittance of the display in normal viewing mode. The angle-of-view adjustment layer may be a second liquid crystal display layer that is used to block off-axis light.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 an array of pixels; and 
 an angle-of-view adjustment layer overlapping the array of pixels, wherein the angle-of-view adjustment layer is operable in a privacy viewing mode in which the angle-of-view adjustment layer restricts an angle of view of the display to a first range of angles and a normal viewing mode in which the angle-of-view adjustment layer opens the angle of view of the display to a second range of angles that is larger than the first range of angles, the angle-of-view adjustment layer comprising:
 first and second electrodes on a first substrate, wherein the second electrodes occupy a smaller area on the first substrate than the first electrodes; 
 a third electrode on a second substrate; and 
 electrophoretic particles between the first and second substrates, wherein the electrophoretic particles are dispersed between the first and second substrates when the angle-of-view adjustment layer is operated in the privacy viewing mode, and wherein the electrophoretic particles are clustered on the second electrodes on the first substrate when the angle-of-view adjustment layer is operated in the normal viewing mode. 
 
 
     
     
       2. The display defined in  claim 1  wherein the angle-of-view adjustment layer comprises pillars of transparent polymer between the first and second substrates and wherein the electrophoretic particles surround the pillars of transparent polymer. 
     
     
       3. The display defined in  claim 1  wherein the pillars of transparent polymer are tapered. 
     
     
       4. The display defined in  claim 3  wherein a distance between adjacent pillars of transparent polymer is smaller near the second substrate than it is near first substrate. 
     
     
       5. The display defined in  claim 1  wherein the first electrodes are uncovered by the electrophoretic particles when the angle-of-view adjustment layer is operated in the normal viewing mode. 
     
     
       6. The display defined in  claim 1  further comprising an upper polarizer, a lower polarizer, and an optical film, wherein the angle-of-view adjustment layer is laminated between the lower polarizer and the optical film. 
     
     
       7. A display, comprising:
 a pixel array configured to display an image; and 
 an angle-of-view adjustment layer overlapping the pixel array, wherein the angle-of-view adjustment layer comprises:
 a first electrode on a first substrate; 
 second and third electrodes on a second substrate, wherein the third electrode comprises a grid of orthogonal lines; and 
 adjustable louvers interposed between the first and second substrates that are formed from electrophoretic particles. 
 
 
     
     
       8. The display defined in  claim 7  wherein the adjustable louvers each have first and second opposing ends, and wherein a width of each louver at the second end is less than  10  microns. 
     
     
       9. The display defined in  claim 7  wherein the angle-of-view adjustment layer comprises transparent polymer in between the louvers. 
     
     
       10. The display defined in  claim 9  wherein the electrophoretic particles are interposed between the first and second electrodes. 
     
     
       11. The display defined in  claim 10  second and third electrodes are patterned. 
     
     
       12. The display defined in  claim 10  wherein the angle-of-view adjustment layer is operable in a first state that restricts a field of view of the display to a first range of angles and a second state that opens up the field of view of the display to a second range of angles, wherein the electrophoretic particles are dispersed between the first and second electrodes when the angle-of-view adjustment layer is operated the first state, and wherein the electrophoretic particles are clustered towards the second electrode when the angle-of-view adjustment layer is operated in the second state. 
     
     
       13. The display defined in  claim 9  wherein the transparent polymer has sloped sides that abut each louver. 
     
     
       14. The display defined in  claim 9  wherein the transparent polymer has straight sides that abut each louver. 
     
     
       15. The display defined in  claim 14  wherein the adjustable louvers each have first and second opposing ends and wherein a width of each louver at the first end is greater than the width at the second end. 
     
     
       16. The display defined in  claim 15  further comprising a backlight, wherein the first end is interposed between the second end and the backlight. 
     
     
       17. The display defined in  claim 7  wherein the louvers form parallel strips extending in a first direction. 
     
     
       18. The display defined in  claim 7  wherein the louvers form a rectangular grid and extend in first and second perpendicular directions.

Description:
This application claims the benefit of provisional patent application No. 62/624,647, filed Jan. 31, 2018, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to electronic devices and, more particularly, to electronic devices with displays. 
     BACKGROUND 
     Electronic devices often include displays. For example, laptop computers have displays. Displays are typically designed to display images over a relatively wide angle of view to accommodate movements in the position of a viewer relative to the display. In some situations, such as when a user of a laptop or other device with a display is using the device in public, the wide viewing angle is undesirable as it compromises privacy. 
     SUMMARY 
     A display may have display layers such as liquid crystal display layers having a liquid crystal layer interposed between a color filter layer and a thin-film transistor layer, organic light-emitting diode layers having organic light-emitting diodes formed from thin-film transistor circuitry, or other types of display layers. 
     An angle-of-view adjustment layer may overlap the display layers. The angle-of-view adjustment layer may include an array of adjustable louvers that move from a first position in which the angle of view of the display is restricted for a private viewing mode and a second position in which the angle of view of the display is not restricted for a normal viewing mode. The louvers may contain electrophoretic particles. The louvers may be tapered and may have a narrow end that is less than ten microns wide to increase transmittance in normal viewing mode. The electrophoretic particles may form isolated clusters on a lower substrate in normal viewing mode to further increase the transmittance of the display in normal viewing mode. 
     The angle-of-view adjustment layer may be a second liquid crystal display layer that is used to block off-axis light. The second liquid crystal layer may be used in conjunction with a lenticular lens array that is interposed between a first liquid crystal display layer and the second liquid crystal display layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device having a display in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative display having an angle-of-view adjustment layer in accordance with an embodiment. 
         FIG. 4  is a top view of an illustrative angle-of-view adjustment layer having adjustable light blocking structures that extend along a first direction in accordance with an embodiment. 
         FIG. 5  is a top view of an illustrative angle-of-view adjustment layer having adjustable light blocking structures that extend along first and second directions in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative angle-of-view adjustment layer having tapered light blocking structures that are positioned in a reduced angle-of-view state in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of the angle-of-view adjustment layer of  FIG. 6  in which the tapered light blocking structures are positioned in a wide angle-of-view state in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative angle-of-view adjustment layer having funnel-shaped light blocking structures that are positioned in a reduced angle-of-view state in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of the angle-of-view adjustment layer of  FIG. 8  in which the funnel-shaped light blocking structures are positioned in a wide angle-of-view state in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative angle-of-view adjustment layer having nozzle-shaped light blocking structures that are positioned in a reduced angle-of-view state in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of the angle-of-view adjustment layer of  FIG. 10  in which the nozzle-shaped light blocking structures are positioned in a wide angle-of-view state in accordance with an embodiment. 
         FIG. 12  is a top view of an illustrative angle-of-view adjustment layer of the type shown in  FIGS. 6, 8, and 10  in which the adjustable light blocking structures are positioned in a reduced angle-of-view state in accordance with an embodiment. 
         FIG. 13  is a top view of an illustrative angle-of-view adjustment layer of the type shown in  FIGS. 7, 9, and 11  in which the adjustable light blocking structures are positioned in a wide angle-of-view state in accordance with an embodiment. 
         FIG. 14  is a top view of an illustrative angle-of-view adjustment layer having first and second electrodes on a substrate for increasing transmittance when the light blocking structures are positioned in a wide angle-of-view state in accordance with an embodiment. 
         FIGS. 15A, 15B, and 15C  are cross-sectional side views of a first region of an angle-of-view adjustment layer of the type shown in  FIG. 14  when the light blocking structures are positioned in a reduced angle-of-view state, an intermediate state, and a wide angle-of-view state, respectively, in accordance with an embodiment. 
         FIGS. 16A, 16B, and 16C  are cross-sectional side views of a second region of an angle-of-view adjustment layer of the type shown in  FIG. 14  when the light blocking structures are positioned in a reduced angle-of-view state, an intermediate state, and a wide angle-of-view state, respectively, in accordance with an embodiment. 
         FIGS. 17A, 17B, and 17C  are top views of an angle-of-view adjustment layer of the type shown in  FIG. 14  when the light blocking structures are positioned in a reduced angle-of-view state, an intermediate state, and a wide angle-of-view state in accordance with an embodiment. 
         FIG. 18  is a top view of an illustrative angle-of-view adjustment layer having patterned electrodes and light blocking structures in a reduced angle-of-view state in accordance with an embodiment. 
         FIG. 19  is a top view of an illustrative angle-of-view adjustment layer having patterned electrodes and light blocking structures in a wide angle-of-view state in accordance with an embodiment. 
         FIG. 20  is a cross-sectional side view of the angle-of-view adjustment layer of  FIG. 19  showing how light blocking particles may gather on patterned electrodes when the display is operated in a normal viewing mode in accordance with an embodiment. 
         FIG. 21  is a top view of an illustrative angle-of-view adjustment layer having light blocking structures and light transmissive structures that form continuous, elongated strips in accordance with an embodiment. 
         FIG. 22  is a top view of an illustrative angle-of-view adjustment layer having light blocking structures and light transmissive structures that form segmented, staggered strips in accordance with an embodiment. 
         FIG. 23  is a cross-sectional side view of an illustrative angle-of-view adjustment layer having tapered light blocking structures with a narrow end facing toward viewers in accordance with an embodiment. 
         FIG. 24  is a cross-sectional side view of an illustrative angle-of-view adjustment layer having tapered light blocking structures with a narrow end facing away from viewers in accordance with an embodiment. 
         FIG. 25  is a cross-sectional side view of an illustrative display having a first display module for providing display content and a second display module for adjusting the angle of view of the display content in accordance with an embodiment. 
         FIG. 26  is a cross-sectional side view of an illustrative display having a first display module for providing display content, a lenticular lens array for adjusting the direction of the display content, and a second display module for selectively blocking some of the display content in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with a display is shown in  FIG. 1 . Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, or other wearable or miniature device, a computer display that does not contain an embedded computer, a computer display that includes an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a laptop computer. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     As shown in  FIG. 1 , device  10  includes a display such as display  14  mounted in housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Housing portions  12 A and  12 B of housing  12  may be connected to each other using hinge structures located along the upper edge of lower housing  12 B and the lower edge of upper housing  12 A. Hinges may allow upper housing  12 A to rotate about axis  22  in directions  24  relative to lower housing  12 B. 
     Display  14  may be mounted in upper housing  12 A. Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. A touch sensor may be formed using electrodes or other structures on a display layer that contains a pixel array or on a separate touch panel layer that is attached to the pixel array (e.g., using adhesive). 
     Display  14  may include an array of pixels formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of electrowetting pixels, an array of organic light-emitting diode pixels, or pixels based on other display technologies. 
     As shown in  FIG. 1 , device  10  may have input-output devices such as track pad  18  and keyboard  16 . Device  10  may also have components such as cameras, microphones, speakers, buttons, status indicator lights, buzzers, sensors, and other input-output devices. These devices may be used to gather input for device  10  and may be used to supply a user of device  10  with output. Connector ports in device  10  may receive mating connectors (e.g., an audio plug, a connector associated with a data cable such as a Universal Serial Bus cable, a data cable that handles video and audio data such as a cable that connects device  10  to a computer display, television, or other monitor, etc.). 
       FIG. 2  is a schematic diagram of device  10 . As shown in  FIG. 2 , electronic device  10  may have control circuitry  26 . Control circuitry  26  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  26  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, etc. 
     Input-output circuitry in device  10  such as input-output devices  28  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  28  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors (e.g., ambient light sensors, proximity sensors, orientation sensors, magnetic sensors, force sensors, touch sensors, etc.), light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  28  and may receive status information and other output from device  10  using the output resources of input-output devices  28 . Input-output devices  28  may include one or more displays such as display  14 . 
     Control circuitry  26  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  26  may display images on display  14  using an array of pixels in display  14 . Display  14  may include adjustable viewing angle control structures such as an adjustable angle-of-view adjustment layer that overlaps the pixels and/or an adjustable backlight. The angle-of-view adjustment layer can be operated in a wide viewing angle mode when privacy is not needed and can be operated in one or more narrow viewing angle modes when privacy is desired. 
     When operated in the restricted angle-of-view mode (sometimes referred to as privacy mode), the angle of view of display  14  is restricted. When the angle of view of display  14  is restricted, it is difficult or impossible for viewers that are located at off-axis positions relative to display  14  to view images on display  14  (e.g., a viewer seated next to the user on an airplane will not be able to view images on display  14 ). At the same time, the user of device  10  who is located in an on-axis position will be able to use display  14  to view images. When operated in an unrestricted angle-of-view mode (sometimes referred to as wide viewing angle mode or normal operation), both on-axis and off-axis viewers will be able to view content on display  14  (i.e., content will not generally be private). 
     Changes in the operating mode of display  14  to implement angle-of-view restrictions (i.e., adjustments to display  14  to place display  14  in normal viewing mode or a reduced-angle-of-view privacy mode) may be made based on user input to input-output devices  28  or may be made automatically by control circuitry  26 . Control circuitry  26  may, for example, use information such as content sensitivity information to determine whether or not content that is being display on display  14  should be displayed in normal mode or privacy mode. If, for example, a user is viewing a movie, the movie may be displayed in normal mode. In the event that a private message such as an incoming text message is detected, display  14  may be placed in privacy mode, thereby ensuring that the content of the text message will not be inadvertently revealed to unauthorized parties. If desired, the angle-of-view adjustment layer for display  14  may be segmented (e.g., using individually adjustable segmented electrodes), so that only a part of display  14  may be placed in privacy mode (e.g., to ensure the privacy of a text message) while the remainder of display  14  is operated normally (e.g. to display a movie). 
     Device  10  may include cameras and other components that form part of gaze and/or head tracking system  30 . The camera(s) or other components of system  30  may face a user&#39;s eyes and may track the user&#39;s eyes and/or head (e.g., images and other information captured by system  30  may be analyzed by control circuitry  26  to determine the location of the user&#39;s eyes and/or head). This eye-location information obtained by system  30  may be used to determine the appropriate direction with which display content from display  14  should be directed. For example, if display  14  is operated in privacy mode using an angle-of-view adjustment layer that restricts the viewing area to a particular region, eye-location information from system  30  may be used to determine the appropriate viewing region and adjust accordingly if the user&#39;s head location changes relative to display  14 . If desired, image sensors other than cameras (e.g., infrared and/or visible light-emitting diodes and light detectors, etc.) may be used in system  30  to monitor a user&#39;s eye and/or head location. 
     A cross-sectional side view of display  14  is shown in  FIG. 3 . Display  14  may have a rectangular shape (i.e., display  14  may have a rectangular footprint and a rectangular peripheral edge that runs around the rectangular footprint) or may have other suitable shapes. Display  14  may be planar, as shown in  FIG. 3 , or may have a curved profile. An adjustable angle-of-view control layer such as angle-of-view adjustment layer  90  may overlap the footprint of display  14 . Angle-of-view adjustment layer  90  may have one or more electrically adjustable structures that control circuitry  26  can control dynamically to place display  14  in a normal viewing mode or a private viewing mode. Layer  90  may, for example, have one or more electrophoretic light blocking structures that can be adjusted to produce a variable amount of viewing angle restriction (adjustable privacy) based on user input, input from sensors, information on the nature of which content is being presented on display  14 , etc. 
     As shown in  FIG. 3 , display  14  may include backlight structures such as backlight unit  42  for producing backlight illumination such as backlight illumination (backlight)  44 . During operation, backlight illumination  44  travels outwards (vertically upwards in dimension Z in the orientation of  FIG. 3 ) and passes through an array of pixels in display layers  46 . This illuminates any images that are being produced by the pixels for viewing by a user. For example, backlight  44  may illuminate images on display layers  46  that are being viewed by viewer  48  in direction  50 . 
     Display layers  46  may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing  12  or display layers  46  may be mounted directly in housing  12  (e.g., by stacking display layers  46  into a recessed portion in housing  12 ). In the example of  FIG. 3 , display layers  46  are liquid crystal display layers and include a liquid crystal layer such as layer  52  (e.g., a layer of liquid crystal molecules sandwiched between a pair of conductive transparent electrodes and polyimide alignment layers). If desired, display layers  46  may be formed from other types of display structures such as light-emitting diode display structures or micro-LED display structures (e.g., an array of discrete light-emitting diodes each of which is formed from a crystalline semiconductor die). In general, display layers  46  may be formed from any suitable type of display (e.g., an electrophoretic display, a plasma display, a display formed from microelectromechanical systems pixels, etc.). 
     In a liquid crystal display, display layers  46  may include a liquid crystal layer such a liquid crystal layer  52 . Liquid crystal layer  52  may be sandwiched between display layers such as display layers  56  and  58 . Layers  56  and  58  may be interposed between lower polarizer layer  60  and upper polarizer layer  54 . 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  58  and  56  may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers  58  and  56  (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers  58  and  56  and/or touch sensor electrodes may be formed on other substrates. 
     With one illustrative configuration, layer  58  may be a thin-film transistor layer that includes an array of pixel circuits based on thin-film transistors and associated electrodes (pixel electrodes) for applying electric fields to liquid crystal layer  52  and thereby displaying images on display  14 . Layer  56  may be a color filter layer that includes an array of color filter elements for providing display  14  with the ability to display color images. If desired, layer  58  may be a color filter layer and layer  56  may be a thin-film transistor layer. Configurations in which color filter elements are combined with thin-film transistor structures on a common substrate layer in the upper or lower portion of display  14  may also be used. Layers  46  may form any suitable type of liquid crystal display (e.g., a fringe-field switching display, a vertical alignment liquid crystal display, a twisted nematic liquid crystal display, an in-plane switching liquid crystal display, an electrically controlled birefringence liquid crystal display, etc.). 
     During operation of display  14  in device  10 , control circuitry  26  (e.g., one or more integrated circuits on a printed circuit) may be used to generate information to be displayed on display  14  (e.g., display data). The information to be displayed may be conveyed to one or more display driver integrated circuits. The display driver circuits may supply data and control signals to an array of pixels in display layers  46  (e.g., pixel circuits in layer  58 , etc.). 
     Backlight structures  42  may include a light guide layer such as light guide layer  78  (sometimes referred to as a light guide structure or light guide). Light guide layer  78  may be formed from one or more stacked layers of transparent material such as clear glass or plastic (e.g., molded plastic that forms a light guide plate, a thin flexible plastic film, etc.). During operation of backlight structures  42 , light sources such as light source  72  may generate light that creates backlight  44 . Light source  72  may be an array of light-emitting diodes that runs along one or more edges of light guide layer  78  such as edge  76  of light guide layer  78  (i.e., into the page along the Y axis in the orientation of  FIG. 3 ). Light-source  72  may emit light  74  into edge  76  of light guide layer  78 . 
     Light  74  may be distributed throughout light guide layer  78  due to the principal of total internal reflection. Scattering features (protrusions, recesses, etc.) may be incorporated into light guide layer  78  (e.g., on the upper and/or lower surface of layer  78 ) to scatter light from layer  78 . Light that is scattered upwards in direction Z from light guide layer  78  may serve as backlight  44  for display  14 . Light that scatters downwards may be reflected back in the upwards direction by reflector  80 . Reflector  80  may be formed from a reflective material such as a layer of plastic covered with a dielectric mirror thin-film coating. 
     To enhance display performance, optical films  70  may be incorporated between backlight structures  42  and layers  46 . Optical films  70  may include diffuser layers for helping to homogenize backlight  44  and thereby reduce hotspots, light collimating films such as prism films (sometimes referred to as brightness enhancement films), polarization recycling films, turning films for directing backlight  44  towards direction Z, and compensation films for enhancing off-axis viewing. Optical films  70  may overlap the other structures in backlight unit  42  such as light guide layer  78  and reflector  80 . For example, if light guide layer  78  has a rectangular footprint in the X-Y plane of  FIG. 3 , optical films  70  and reflector  80  may have a matching rectangular footprint. If desired, films such as compensation films may be incorporated into other layers of display  14  (e.g., a polarizer layer). 
     Angle-of-view adjustment layer  90  may be operated in multiple viewing modes such as a normal angle-of-view mode and one or more reduced angle-of-view modes. When operated in a normal angle-of-view mode, viewer  48  can view images on display  14  over a relatively wide range of angles A. When privacy is desired, display  14  can be operated in the reduced angle-of-view mode. In this mode, viewer  48  can view images on display  14  over a more restricted range of angles (see, e.g., reduced angle-of-view range B, where B&lt;A, B &lt;60% of A, where B&lt;40% of A, etc.). 
     As shown in  FIG. 3 , layer  90  may include one or more light adjustment layers such as light transmission adjustment layer  92  interposed between transparent electrodes  96  and  98 . Control circuitry  26  may control the operation of layer  90  by applying controlled amounts of electric field to layer  92  using electrodes  96  and  98 . Electrodes  96  and  98  may be formed from transparent conductive material such as indium tin oxide and may be supported by transparent planar members such as clear substrates  100  (e.g., glass, plastic, etc.). Polarizer layers and/or other layers in display  14  may also serve as substrates for electrodes  96  and  98 . The use of substrates  100  to support electrodes  96  and  98  in  FIG. 3  is merely illustrative. Electrodes  96  and  98  may be blanket conductive layers or one or both of electrodes  96  and  98  may be patterned. 
     Light transmission adjustment layer  92  may include light blocking structures  102  interspersed with light transmissive structures  104 . Light transmissive structures  104  (sometimes referred to as transparent polymer  104 ) may be an optically clear material such as acrylic or other transparent polymer. Light blocking structures  102  may include particles  94  (e.g., charged electrophoretic particles of dark ink such as carbon black ink) suspended in fluid or other transparent medium  108 . Light blocking structures  102  may serve as electrically controllable louvers for restricting the angle of view of display  14 . When display  14  switches into private viewing mode, control circuitry  26  may remove the electric field applied to layer  92 , causing particles  94  to disperse throughout medium  108 . As shown in  FIG. 3 , light blocking structures  102  may have a first height such as height H when operated in private viewing mode to block off-axis light at wide viewing angles. When display  14  is operated in a normal viewing mode, control circuitry  26  may apply a voltage across electrodes  96  and  98 , creating an electric field in layer  92  that causes particles  94  to move towards the electrode having an opposite charge from that of particles  94 . For example, in arrangements where lower electrode  96  has opposite charge from that of particles  94 , light blocking structures  102  may collapse towards lower electrode  96  to a height that is less than height H to allow off-axis light at wide viewing angles to exit display  14 . 
     In the example of  FIG. 3 , angle-of-view adjustment layer  90  is laminated between lower polarizer  60  and optical films  70 . This type of arrangement may ensure that optical films  70  are able to efficiently recycle light from backlight  42 . This is, however, merely illustrative. If desired, angle-of-view adjustment layer  90  may be interposed between optical films  70  and light guide layer  78 , may be located above upper polarizer  54 , or may be located in other suitable locations in display  14 . 
       FIG. 4  is a top view of an illustrative arrangement for light transmission adjustment layer  90  in which light blocking structures  102  are formed in parallel strips that extend along a first direction (e.g., along the Y direction, as shown in the example of  FIG. 4 , or along the X direction). Layer  92  of  FIG. 4  may be formed from a layer of transparent polymer  104  that has been embossed or photolithographically patterned to form elongated trenches in transparent polymer  104 . The trenches may be filled with light blocking structures  102  (e.g., black ink particles  94  suspended in a transparent medium  108 ). Arrangements of the type shown in  FIG. 4  are sometimes referred to as one-dimensional louvers because light blocking structures  102  are configured to restrict the horizontal field of view (e.g., the field of view along dimension X of  FIG. 4 ). 
       FIG. 5  is a top view of an illustrative arrangement for adjustable light transmission layer  92  in which light blocking structures  102  are formed in a rectangular grid that extends along first and second directions (e.g., along the X and Y directions of  FIG. 5 ). Layer  92  of  FIG. 5  may be formed from a layer of transparent polymer  104  that has been embossed or photolithographically patterned to form a grid of trenches in transparent polymer  104 . The trenches may be filed with light blocking structures  102  (e.g., black ink particles suspended in transparent medium  108 ). As shown in  FIG. 5 , light blocking structures  102  may completely surround each transmissive polymer structure  104 . Whereas transparent polymer structures  104  of  FIG. 4  have a wall shape, transparent polymer structures  104  of  FIG. 5  have a pillar shape and are sometimes referred to as micro-rods. Configurations of the type shown in  FIG. 5  are sometimes referred to as two-dimensional louvers because light blocking structures  102  are configured to restrict the horizontal field of view (e.g., the field of view along dimension X of  FIG. 5 ) and the vertical field of view (e.g., the field of view along dimension Z of  FIG. 5 ). 
     Due to the presence of light blocking particles  94 , care must be taken to ensure that transmittance is not significantly reduced when display  14  is operated in a normal wide viewing mode.  FIGS. 6-24  show illustrative examples for configuring angle-of-view adjustment layer  90  so that light blocking particles  94  do not significantly affect transmittance when display  14  is operated in a normal viewing mode. These examples may be implemented with a one-dimensional louver arrangement of the type shown in  FIG. 4  or a two-dimensional louver arrangement of the type shown in  FIG. 5 . Arrangements in which layer  90  includes a two-dimensional louver structure are sometimes described as an illustrative example. 
       FIG. 6  is a cross-sectional side view of an illustrative angle-of-view adjustment layer  90  having tapered light blocking structures  102 . As shown in  FIG. 6 , the width W1 at the lower surface of light blocking structures  102  may be smaller than the width W2 at the upper surface of light blocking structures  102 . Width W1 may be about 5 microns, about 10 microns, between 5 and 10 microns, between 2 and 5 microns, between 3 and 14 microns, between 2 and 20 microns, greater than 10 microns, or less than 10 microns. The angle θ between the lower substrate  100  and the side surface of light blocking structure  102  may, for example, be about 85°, about 86°, about 84°, between 80° and 90°, between 85° and 95°, between 83° and 88°, greater than 88°, or less than 88°. When it is desired to operate display  14  in private mode, control circuitry  26  does not apply a voltage across terminal  32  (coupled to electrode  98 ) and terminal  34  (coupled to electrode  96 ). The absence of an electric field will cause particles  94  to disperse throughout medium  108 , forming a light blocking structure  102  of height H 1 . 
     When it is desired to operate display  14  in normal or non-private mode, control circuitry  26  applies a voltage across terminals  32  and  34  to produce an electric field in layer  92 . As shown in  FIG. 7 , this causes particles  94  to cluster towards lower electrode  96 , reducing the height of light blocking structures  102  to height H 2 . Because of the taper shape of light blocking structures  102 , particles  94  take up less space in the X and Y dimensions, thereby allowing more light through when display  14  is operated in normal viewing mode. 
     In the example of  FIGS. 8 and 9 , light blocking structures  102  have a funnel shape. As in the example of  FIGS. 6 and 7 , the width of light blocking structures  102  is greater near upper electrode  98  than it is near lower electrode  96 . In this example, the upper portion of each light blocking structure  102  has straight vertical sides and the lower portion of each light blocking structure  102  has sloped sides that form a funnel shape. When light blocking structures  102  are operated in private viewing mode, as shown in  FIG. 8 , particles  94  disperse throughout medium  108  to restrict off-axis viewing. When light blocking structures  102  are operated in a normal viewing mode, particles  94  cluster in a small area near electrode  96  to ensure that wide viewing angles are not restricted by particles  94 . 
     In the example of  FIGS. 10 and 11 , light blocking structures  102  have a nozzle shape. The width of light blocking structures  102  is greater near upper electrode  98  than it is near lower electrode  96 . In this example, each light blocking structure  102  has a narrower lower portion with straight vertical sides and a wider upper portion with straight vertical sides. If desired, light blocking structures  102  may have additional portions with wider or narrower widths (e.g., light blocking structures  102  may have three or more portions with progressively narrower widths). The example of  FIGS. 10 and 11  is merely illustrative. When light blocking structures  102  are operated in a private viewing mode, as shown in  FIG. 10 , particles  94  disperse throughout medium  108  to restrict off-axis viewing. When light blocking structures  102  are operated in a normal viewing mode, particles  94  cluster in a small area near electrode  96  to ensure that wide viewing angles are not restricted by particles  94 . 
     The example of  FIGS. 6-11  in which particles  94  cluster towards lower electrode  96  is merely illustrative. If desired, electrode  98  may have opposite charge from that of particles  94  so that particles  94  migrate towards electrode  98  in normal viewing mode. In this type of arrangement, the shape of light blocking structure  102  may be reversed, so that the width of light blocking structure  102  is smaller near upper electrode  98  than it is near lower electrode  96 . 
       FIGS. 12 and 13  show top views of an illustrative angle-of-view adjustment layer  90  of the type shown in  FIGS. 6-11 .  FIG. 12  shows angle-of view adjustment layer  90  in a private viewing mode state, and  FIG. 13  shows angle-of-view adjustment layer  90  in a normal mode viewing state. As shown in  FIG. 12 , the wider upper width W2 of light blocking structures  102  restricts the transmissive area of layer  90  to width W3 when display  14  is operated in private viewing mode. As shown in  FIG. 13 , the narrower lower width W1 of light blocking structures  102  opens the transmissive area of layer  90  to width W4 , which is greater than width W3 . 
       FIGS. 14-17C  show an illustrative arrangement for angle-of-view adjustment layer that employs multiple lower electrodes to further increase transmittance of display  14  when display  14  is operated in normal viewing mode. As shown in the top view of  FIG. 14 , angle-of-view adjustment layer  90  may have first electrodes  96 - 1  and second electrodes  96 - 2  formed on lower substrate  100 . First electrodes  96 - 2  may be located along the sides of transmissive structures  104 , whereas second electrodes  96 - 2  maybe located at the corners of transmissive structures  104 . If desired, second electrodes  96 - 2  may occupy a smaller area on substrate  100  than first electrodes  96 - 1 . This is, however, merely illustrative. Electrodes  96 - 1  and  96 - 2  may have any suitable shape, size, number, and location on substrate  100 . 
     When display  14  is operated in normal viewing mode, an appropriate electric field may be applied to cause particles to cluster on electrodes  96 - 2 . This leaves electrodes  96 - 1  uncovered by particles  94  and allows light to pass through first electrodes  96 - 1  when display  14  is operated in normal viewing mode. 
       FIGS. 15A, 15B, and 15C  are cross-sectional side views of angle-of-view adjustment layer  90  taken along line  110  and viewed in direction  112  of  FIG. 14 . These figures show the progression of particles  94  as particles  94  move from a private viewing mode state ( FIG. 15A ), to an intermediate state ( FIG. 15B ), to a normal viewing mode state ( FIG. 15C ). 
     As shown in  FIG. 15A , the absence of an applied electric field causes particles  94  to disperse throughout medium  108 , thereby restricting off-axis viewing of display  14 . 
     When it is desired to switch into normal viewing mode, control circuitry  26  may apply a first electric field El across layer  92 , as shown in  FIG. 15B . This may be achieved by applying a first voltage (e.g., 20 Volts, for example) to lower electrodes  96 - 1  and  96 - 2  and applying a second voltage (e.g., 0 Volts, for example) to upper electrode  98 . This causes particles  94  to move in dimension Z towards lower electrodes  96 - 1  and  96 - 2 . 
     After particles  94  migrate to lower electrodes  96 - 1  and  96 - 2 , control circuitry  26  may apply a second electric field E2 across layer  92 , as shown in  FIG. 15C . This may be achieved by applying a first voltage (e.g., 0 Volts, for example) to electrodes  98  and  96 - 1  and applying a second voltage (e.g., 20 Volts, for example) to electrodes  96 - 2 . This causes particles  94  to cluster on second electrodes  96 - 2 , leaving first electrodes  96 - 1  uncovered and able to transmit light in normal viewing mode. 
       FIGS. 16A, 16B, and 16C  are cross-sectional side views of angle-of-view adjustment layer  90  taken along line  114  and viewed in direction  116  of  FIG. 14 . Similar to  FIGS. 15A, 15B, and 15C , these figures show the progression of particles  94  as particles  94  move from a private viewing mode state ( FIG. 16A ), to an intermediate state ( FIG. 16B ), to a normal viewing mode state ( FIG. 16C ). 
     As shown in  FIG. 16A , the absence of an applied electric field causes particles  94  to disperse throughout medium  108 , thereby restricting off-axis viewing of display  14 . 
     When it is desired to switch into normal viewing mode, control circuitry  26  may apply a first electric field El across layer  92 , as shown in  FIG. 16B . This causes particles  94  to move along dimension Z towards lower electrodes  96 - 1  and  96 - 2 . 
     After particles  94  migrate to lower electrodes  96 - 1  and  96 - 2 , control circuitry  26  may apply a second electric field E2 across layer  92 , as shown in  FIG. 16C . This causes particles  94  to cluster on second electrodes  96 - 2  (as shown in  FIG. 15C ), leaving first electrodes  96 - 1  uncovered and able to transmit light in normal viewing mode. 
       FIGS. 17A, 17B, and 17C  show top views of light blocking structures  102  as particles  94  move from a private viewing mode state ( FIG. 17A , which is a top view of  FIGS. 15A and 16A ), to an intermediate state ( FIG. 17B , which is a top view of  FIGS. 15B and 16B ), to a normal viewing mode state ( FIG. 17C , which is a top view of  FIGS. 15C and 16C ). 
     As shown in  FIG. 17A , the absence of an applied electric field causes particles  94  to disperse throughout medium  108 , thereby restricting off-axis viewing of display  14 . In this state, light blocking structures  102  form a rectangular grid surrounding transmissive structures  104 . 
     When it is desired to switch into normal viewing mode, control circuitry  26  may apply a first electric field El across layer  92 , which causes particles  94  to move towards lower electrodes  96 - 1  and  96 - 2  (e.g., along the Z dimension of  FIG. 17B ). 
     After particles  94  migrate to lower electrodes  96 - 1  and  96 - 2 , control circuitry  26  may apply a second electric field E2 across layer  92 , causing particles  94  to move along dimensions X and Y towards second electrodes  96 - 2  (as shown in  FIG. 15C ). This means that regions  104  and  102 - 1 , which overlap first electrodes  96 - 1 , are transmissive, whereas regions  102 - 2 , which overlap second electrodes  96 - 2 , are non-transmissive. This ensures that transmittance of display  14  is not significantly reduced when display  14  is operated in a normal viewing mode. 
       FIG. 18  shows another illustrative arrangement for an angle-of-view adjustment layer  90  that employs a pattern of lower electrodes to further increase transmittance of display  14  when display  14  is operated in normal viewing mode. As shown in the top view of  FIG. 18 , angle-of-view adjustment layer  90  may have a pattern of electrodes  96  on lower substrate  100 . Electrodes  96  may be elongated strips that extend parallel to the X axis of  FIG. 18 , whereas light blocking structures  102  and light transmissive structures  104  extend parallel to the Y axis of  FIG. 18 . The example of  FIG. 18  in which electrodes  96  form continuous, elongated strips is merely illustrative. If desired, electrodes  96  may be segmented, may be staggered, may follow a curved, angled, meandering, or random path, and/or may have any other suitable pattern. 
     As shown in  FIG. 18 , the absence of an applied electric field causes particles  94  to disperse throughout medium  108  ( FIG. 3 ), thereby restricting off-axis viewing of display  14 . In this state, light blocking structures  102  form elongated strips between light transmissive structures  104 . 
     When it is desired to switch into normal viewing mode, control circuitry  26  may apply an electric field across layer  92  ( FIG. 3 ), which causes particles  94  to gather on electrodes  96 , as shown in  FIG. 19 . The use of patterned electrodes  96  may therefore increase transmittance by allowing the spaces between electrodes  96  to be transparent in normal viewing mode. 
       FIG. 20  is a cross-sectional side view of angle-of-view adjustment layer  90  of  FIG. 19  taken along line  150  and viewed in direction  152 . As shown in  FIG. 20 , particles  94  may accumulate on and be confined to patterned electrodes  96  on substrate  100  when control circuitry  26  applies an electric field across layer  92 . This allows light from backlight  46  to be transmitted through gaps  154  between electrodes  96 , thereby increasing the transmittance of layer  90  when display  14  is operated in normal viewing mode. 
       FIG. 21  is a top view of angle-of-view adjustment layer  90  showing how light blocking structures  102  and light transmissive structures  104  may form elongated, continuous strips extending across substrate  100  parallel to the Y axis of  FIG. 21 . This is, however, merely illustrative. As shown in  FIG. 22 , light blocking structures  102  and light transmissive structures  104  may be segmented strips extending parallel to the Y axis of  FIG. 22 . In general, any suitable pattern of light blocking structures  102  and light transmissive structures  104  may be used in display  14 . The examples of  FIGS. 21 and 22  are merely illustrative. 
       FIG. 23  is a cross-sectional side view of angle-of-view adjustment layer  90  showing how the narrower end such as narrow end  140  of light blocking structures  102  may face viewer  50  and the wider end such as wider end  142  of light blocking structures  102  may face backlight  42  ( FIG. 3 ). Placing narrow end  140  towards viewer  50  and wider end  142  towards backlight  42  may help increase transmittance of layer  90  when display  14  is operated in normal viewing mode. This is, however, merely illustrative. If desired, layer  90  may have an arrangement of the type shown in  FIG. 24 , in which narrow end  140  faces backlight  42  ( FIG. 3 ) and wider end  142  faces viewer  50 . 
     If desired, angle-of-view adjustment layer  90  may be implemented using liquid crystal display structures. An arrangement of this type is shown in  FIG. 25 . As shown in  FIG. 25 , display layers  46  may include pixels  38  and angle-of-view adjustment layer  90  may include pixels  40 . Pixels  40  may be liquid crystal pixels having a layer of liquid crystal material interposed between transparent electrodes. Control circuitry  26  may control the operation of layer  90  by applying controlled amounts of electric field to the liquid crystal layer using the electrodes. 
     Display layers  46  may be used to provide display content and angle-of-view adjustment layer  90  may be used to adjust the angles at which the display content is viewable. As shown in  FIG. 25 , for example, select pixels  38  and pixels  40  may be activated to transmit on-axis light towards viewer  48 - 1 , whereas other pixels  38  and pixels  40  may be inactivated to block off-axis light from reaching viewer  48 - 2 . If desired, control circuitry  26  may use head tracking system  30  to track the head or eyes of viewer  48 - 1  and to adjust the direction of light according to the location of the user&#39;s head. For example, if system  30  detects movement of viewer  48 - 1  in direction  120 , control circuitry  46  may shift activated pixels  38  in direction  122  and/or may shift activated pixels  40  in direction  120 . 
       FIG. 26  shows an illustrative arrangement in which angle-of-view adjustment layer  90  is implemented in combination with a lens array such as lenticular lenses  124 . As in the example of  FIG. 25 , display layers  46  may be used to provide display content and angle-of-view adjustment layer  90  may be used to adjust the angles at which the display content is viewable. Lenticular lenses  124  may be used to bend light from display layers  46  to help steer light to the appropriate viewer. For example, select pixels  38  and pixels  40  may be activated to transmit on-axis light towards viewer  48 - 1 , whereas other pixels  38  and pixels  40  may be inactivated to block off-axis light from reaching viewer  48 - 2 . Lenticular lenses  124  may be used to help steer light  44 - 1  towards viewer  48 - 1 . This additional steering helps block off extreme wide viewing angles that might otherwise be viewable on display  14 . If desired, control circuitry  26  may use head tracking system  30  to track the head or eyes of viewer  48 - 1  and to adjust the direction of light according to the location of the user&#39;s head. For example, if system  30  detects movement of viewer  48 - 1  in direction  120 , control circuitry  46  may shift activated pixels  38  in direction  122  and/or may shift activated pixels  40  in direction  120 . 
     If desired, display  14  may achieve adjustable angle of view using a directional backlight in conjunction with a lenticular lens array. In this type of arrangement, only one display module (e.g., display layers  46 ) is needed, although more may be used if desired. The backlight may be a two-dimensional backlight (e.g., a two-dimensional array of light sources that overlap display layers  46 ). Control circuitry  26  may adjust the angle of view by adjusting the directional backlight so that light reaches on-axis viewers and is blocked from off-axis viewers when display  14  is operated in private mode. If desired, control circuitry  26  may use head tracking system  30  to track the head or eyes of viewer  48 - 1  and to adjust the direction of light according to the location of the user&#39;s head. 
     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: 20190129
Publication Date: 20220920
Grant Date: 20220920
Priority Date: 20180131
Inventors: FAN JIANG, SHIH-CHYUAN
JOHNSON, PAUL V.
AHN, SE HYUN
CHEN, CHENG
CHEN, YUAN
CHOI, Hyungryul
GE, ZHIBING
LIGTENBERG, CHRISTIAAN A.
MATHEW, DINESH C.
SONG, HYUNMIN A.
WANG, CHAOHAO
WU, JIAYING
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/012", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2358/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/028", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/36", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G3/344", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3406", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/023", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2354/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1676", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2354/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1347", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/012", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/167", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1677", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/028", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/068", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133526", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1323", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1676", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/068", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/167", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/028", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133526", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2354/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1323", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1347", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/012", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1677", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/1323", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/167", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133524", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 83286299