PATENT DOCUMENT

Publication Number: US-10496164-B2
Application Number: US-201715835046-A
Country: US
Kind Code: B2

Title: Electronic device with adjustable reflective display

Abstract:
An electronic device may have a display. Input-output circuitry in the electronic device may be used to gather input from a viewer of the display. The input-output circuitry may include a gaze tracking system that gathers point-of-gaze information, vergence information, and head position information, may be a biometric sensor, may be an input device such as a button or touch sensor, may capture hand gestures, and/or may gather other information. The display may include a pixel array for producing images. An adjustable reflectance and transmittance layer may overlap the pixel array. Control circuitry in the electronic device may individually adjust different areas of the adjustable reflectance and transmittance layer. The control circuitry may place each area in a reflective mirror more or in a content-displaying mode and may move the areas in response to the information.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a display having a pixel array configured to produce images, a linear polarizer overlapping the pixel array, and first and second reflective polarizers overlapping the linear polarizer; 
 input-output circuitry that is configured to gather input; and 
 control circuitry that is configured to:
 display content with the pixel array in response to the input; 
 place a first area of the display in a mirror configuration that is reflective to ambient light and that blocks the images from the pixel array; and 
 place a second area of the display that is different from the first area in a content-displaying configuration that is transparent to the images from the pixel array and that is not reflective to ambient light, wherein the control circuitry moves the first and second areas relative to each other on the display in response to the input. 
 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the display comprises a liquid crystal layer between the first and second reflective polarizers. 
     
     
       3. The electronic device defined in  claim 2  further comprising a pair of transparent electrodes configured to apply electric fields to the liquid crystal layer. 
     
     
       4. The electronic device defined in  claim 3  further comprising a switchable polarizer, wherein the second reflective polarizer is interposed between the switchable polarizer and the liquid crystal layer. 
     
     
       5. The electronic device defined in  claim 4 , wherein the pair of transparent electrodes is configured to apply electric fields to the liquid crystal layer, wherein the pair of transparent electrodes, the liquid crystal layer, and the switchable polarizer have independently adjustable areas on the display that receive signals from the control circuitry that adjust ambient light reflectance and image transmittance from the pixel array in response to control signals from the control circuitry. 
     
     
       6. The electronic device defined in  claim 2  further comprising a switchable polarizer, wherein the control circuitry is configured to adjust the switchable polarizer and the liquid crystal layer to place the first area of the display in the mirror configuration and to place the second area of the display in the content-displaying configuration. 
     
     
       7. The electronic device defined in  claim 6 , wherein the input-output circuitry comprises a head positioning tracking system and wherein the input comprises head location information. 
     
     
       8. The electronic device defined in  claim 6 , wherein the input-output circuitry comprises a gaze tracking system and wherein the input comprise point-of-gaze information. 
     
     
       9. The electronic device defined in  claim 6 , wherein the input-output circuitry comprises a hand gesture tracking system and wherein the input comprises hand gestures. 
     
     
       10. The electronic device defined in  claim 6 , wherein the input-output circuitry is configured to measure vergence information that serves as the input. 
     
     
       11. The electronic device defined in  claim 1 , wherein the first reflective polarizer has a first pass axis, wherein the second reflective polarizer has a second pass axis, and wherein the first and second pass axes are parallel to each other. 
     
     
       12. The electronic device defined in  claim 1 , wherein the first reflective polarizer has a first pass axis, wherein the second reflective polarizer has a second pass axis, and wherein the first and second pass axes are separated by an angle from 30° to 70°. 
     
     
       13. The electronic device defined in  claim 1  further comprising a clear layer of material between the first and second reflective polarizers. 
     
     
       14. The electronic device defined in  claim 13 , wherein the clear layer of material comprises a polymer layer having a thickness of 50-110 microns. 
     
     
       15. An electronic device, comprising:
 a display having a pixel array configured to produce images, a linear polarizer overlapping the pixel array, a first reflective polarizer, a second reflective polarizer, an adjustable liquid crystal layer between the first and second reflective polarizers, and an adjustable polarizer, wherein the second reflective polarizer is between the adjustable liquid crystal layer and the adjustable polarizer; 
 a tracking system that gathers input; and 
 control circuitry that is configured to:
 place a first portion of the display in a content-displaying mode in which ambient light reflectance is reduced and content is displayed with the pixel array; 
 place a second portion of the display in a mirror mode in which display ambient light reflectance is enhanced; and 
 adjust where the first and second portions are located on the display in response to the input. 
 
 
     
     
       16. The electronic device defined in  claim 15 , wherein the tracking system has a camera and wherein the input comprises head position information gathered with the camera. 
     
     
       17. The electronic device defined in  claim 15 , wherein the tracking system comprises a gaze tracking system and wherein the input comprises vergence information gathered with the gaze tracking system. 
     
     
       18. An adjustable mirror display, comprising:
 a pixel array configured to produce images; 
 an adjustable reflectance and transmittance layer having multiple independently adjustable areas each of which operates in at least a mirror mode in which ambient light is reflected and the images are not transmitted and a content-displaying mode in which the images are transmitted for viewing and ambient light reflections are reduced relative to the mirror mode; 
 a tracking system that includes a camera; and 
 control circuitry that adjusts which of the independently adjustable areas operate in the mirror mode and which of the independently adjustable areas operate in the content-displaying mode based on information from the tracking system. 
 
     
     
       19. The adjustable mirror display defined in  claim 18 , wherein the adjustable reflectance and transmittance layer comprises:
 a linear polarizer through which the images are transmitted; 
 a first reflective polarizer having a first pass axis; 
 a second reflective polarizer having a second pass axis that is parallel to the first pass axis; 
 an adjustable liquid crystal layer between the first and second reflective polarizers; and 
 an adjustable polarizer containing liquid crystal molecules and dichroic dye molecules and wherein the adjustable mirror display further comprises input-output circuitry that gathers biometric information.

Description:
This application claims the benefit of provisional patent application No. 62/432,275, filed Dec. 9, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with displays. 
     Devices such as computer monitors and televisions contain arrays of pixels for displaying images for a user. Displays such as these generally exhibit low reflectivity and are unsuitable for applications involving high reflectance, adjustable reflectance capabilities, and other adjustable features. 
     SUMMARY 
     An electronic device may have a display. Input-output circuitry in the electronic device may be used to gather input from a viewer of the display. The input-output circuitry may include a gaze tracking system that gathers point-of-gaze information, vergence information, and head position information, may be a biometric sensor, may be an input device such as a button or touch sensor, may capture hand gestures, and/or may gather other information. This information may be used by control circuitry in the electronic device to dynamically adjust the display. 
     The display may include a pixel array for producing images. An adjustable reflectance and transmittance layer may overlap the pixel array. The adjustable reflectance and transmittance layer may have a linear polarizer, reflective polarizers, an adjustable liquid crystal layer for controlling polarization rotation, and a switchable polarizer. The switchable polarizer may include liquid crystal molecules and dichroic dye molecules. 
     Control circuitry in the electronic device may individually adjust different areas of the adjustable reflectance and transmittance layer by supplying control signals to the adjustable liquid crystal layer and to the switchable polarizer in each of these areas. The control circuitry may place each area in a reflective mirror mode or in a content-displaying mode. The locations of mirror mode regions and content-displaying regions may be moved with respect to each other in response to information from the input-output circuitry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device with a display in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative display having a pixel array covered with an adjustable reflectance and transmittance layer in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative adjustable reflectance and transmittance layer in a first operating mode such as a reflective mode of operation in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of the adjustable reflectance and transmittance layer of  FIG. 3  in a second mode of operation such as a non-reflective transparent mode of operation in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative adjustable polarizer in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative reflective display with a single reflective polarizer layer in accordance with an embodiment. 
         FIG. 7  is an exploded perspective view of an illustrative reflective display with multiple reflective polarizer layers in accordance with an embodiment. 
         FIG. 8  is a front view of an illustrative display with independently adjustable segmented areas of varying reflectivity and transmission in accordance with an embodiment. 
         FIGS. 9 and 10  are top views of illustrative displays and an associated viewer showing how viewer head position may be measured and used in adjusting which areas of the displays are reflective and which areas of the display are non-reflective in accordance with an embodiment. 
         FIG. 11  is a perspective view of an illustrative display with a first area that is displaying an icon or other content and a second area that is being operated in a reflective mode while a viewer&#39;s point-of-gaze is being measured using a gaze detection system in accordance with an embodiment. 
         FIG. 12  is a top view of an illustrative display showing how display operation may be adjusted dynamically based on measured vergence information from a user&#39;s eyes in accordance with an embodiment. 
         FIG. 13  is a flow chart of illustrative steps involved in operating a device of the type shown in  FIG. 1  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with reflective displays. Input-output circuitry may be incorporated into the devices to gather point-of-gaze information, head position information, and other input. A reflective display may include one or more layers that provide some or all of the surface of the display with an elevated reflectivity. If desired, adjustable reflectivity and transmittance regions may be provided on a reflective display so that some portions of a display may be dynamically rendered reflective while other portions of the display are rendered non-reflective and are used to display content for a user. Control circuitry may dynamically rearrange the locations of the reflective and non-reflective portions based on input from the input-output circuitry. 
     An illustrative electronic device of the type that may be provided with a reflective display is shown in  FIG. 1 . Electronic device  10  may be a cellular telephone, a tablet computer, a laptop, desktop computer, or wall mounted computer, a television, a wrist watch, or other electronic equipment that includes a display. As shown in  FIG. 1 , electronic device  10  may have control circuitry  20 . Control circuitry  20  may include storage and processing circuitry for controlling the operation of device  10 . Circuitry  20  may include storage such as hard disk drive storage, nonvolatile memory (e.g., 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 based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application specific integrated circuits, and other integrated circuits. Software code may be stored on storage in circuitry  20  and run on processing circuitry in circuitry  20  to implement control operations for device  10  (e.g., operations involving gathering data using sensors and user input devices, operations involving the adjustment of displays and other components using control signals based on gathered data and other information, operations associated with gathering and producing content for displaying to a user, etc.). 
     Device  10  may include input-output circuitry  22 . Input-output circuitry  22  and/or control circuitry  20  may include communications circuitry such as wired and/or wireless communications circuitry. The communications circuitry in device  10  may be used to allow data to be received by device  10  from external equipment (e.g., a computer, a portable device such as a handheld device or laptop computer, a server or other computer coupled to the internet or a local area network, a wristwatch device or other wearable device, or other electrical equipment). The communications circuitry in device  10  may also be used to transmit data from device  10  to a computer, portable device, or other external equipment. During operation, input-output circuitry  22  may be used to gather information on the environment in which device  10  is operating. Output components in circuitry  22  may allow device  10  to provide a user with output and may be used to communicate with external electrical equipment. 
     As shown in  FIG. 1 , input-output circuitry  22  may include a display such as display  14 . Display  14  may be used to display images for a user of device  10 . Display  14  may be an organic light-emitting diode display, a liquid crystal display, a liquid-crystal-on-silicon display, or any other suitable display. Display  14  may be a reflective display that reflects ambient light and therefore provides display  14  or part of display  14  with a mirror-like appearance. If desired, display  14  may include adjustable reflectance and transmittance layer(s) that can be adjusted dynamically to alter the amount of ambient light that is reflected by display  14  (e.g., the reflectivity of display  14 ) and that can be adjusted dynamically to exhibit varying amounts of transparency. The adjustable reflectivity and transmission structures in display  14  may be adjusted dynamically by control circuitry  20  in one or more areas of display  14 . For example, display  14  may include a segmented (pixelated) dynamically adjustable reflectance and transmittance layer. During operation, control circuitry  20  can supply control signals to each segmented region of the adjustable reflectance of transmittance layer to independently adjust the reflectance and transmittance levels for that region. In this way, reflective and non-reflective areas of display  14  may be moved relative to each other on display  14 . 
     Input-output circuitry  22  may include components that form one or more tracking systems such as tracking system  16 . System  16  may include one or more cameras (visible light cameras, infrared cameras, etc.), may include one or more light sources (e.g., light-emitting diodes, lasers, lamps, or other sources of light that produce glints on a user&#39;s eye for eye tracking), may include proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors, etc.), and may include other input-output devices. These components may be used to form a gaze tracking system (e.g., a system that emits spots of light that reflect from a viewer&#39;s eyes and that uses images from a camera to detect a point-of-gaze for each of the viewer&#39;s eyes). 
     A gaze tracking (eye monitoring) system for device  10  may, for example, include image sensors, light sources, and/or other equipment that is used in monitoring the eyes of the viewer. This system may include one or more visible and/or infrared cameras that face a viewer&#39;s eyes and capture images of the viewer&#39;s (user&#39;s) eyes. During operation of device  10 , control circuitry  20  may use the gaze tracking system to track a viewer&#39;s gaze. Cameras and/or other sensors in system  16  may, for example, determine the location of a viewer&#39;s eyes (e.g., the centers of the viewer&#39;s pupils) and may determine the direction in which the viewer&#39;s eyes are oriented (the direction of the viewer&#39;s gaze, sometimes referred to as the viewer&#39;s point of gaze). 
     Eye orientation for the viewer&#39;s right and left eyes may be analyzed to obtain vergence information (information on the amount by which both of the viewer&#39;s eyes rotate towards or away from each other as the viewer is focusing on a near or far object). Measured vergence information may be used in addition to information on the viewer&#39;s overall direction of view to determine the viewer&#39;s point-of-gaze in three dimensions. For example, if the viewer&#39;s eyes are both pointed to the right and if vergence information reveals that the viewer is focusing on an object three feet away, tracking system  16  can conclude that the viewer&#39;s point-of-gaze is directed towards an object to the right that is three feet from the viewer&#39;s eyes. If desired, system  16  may capture additional types of eye data. For example, information on-eye movements such as fixations and saccades may be gathered by system  16 . System  16  may also gather information on viewer pupil size and blink rate and/or other eye parameters. 
     Head position information may be obtained by measuring eye position (e.g., system  16  may serve both as a gaze tracking and head tracking system). Configurations in which head tracking and gaze tracking operations are performed using different components and/or different processors may also be used. Because system  16  may be used for tracking viewer attributes such as point-of-gaze, eye location, vergence, pupil size, blink rate, eye movement information such as information on fixations and saccades, head position, and viewer hand motions, system  16  may sometimes be referred to as a viewer (user) tracking system. 
     By processing information from tracking system  16 , system  10  may make adjustments to display  14  that affect the appearance of display  14  (e.g., the ambient light reflectance of one or more portions of display  14 , the transmittance for images in one or more portions of display  14 , the content displayed in one or more portions of display  14 , etc.). Information from system  16  on the location on display  14  where a viewer&#39;s gaze is currently directed and the amount of time that the viewer dwells on particular on-screen items may be used as a form of user input (viewer input) to system  10 . Other eye information (information on vergence, pupil size, blink rate, eye movement information such as information on fixations and saccades, etc.), and/or other eye information gathered with system  16  may also be used in controlling the operation of device  10 . In some arrangement, gaze tracking system output may be used in conjunction with mouse clicks, screen taps and other touch screen or track pad touch gestures, voice commands, video game controller commands, and/or other user commands as a form of user input to device  10 . 
     User input and other information may be gathered using sensors and other input devices in input-output devices  18 . Input-output devices  18  may include, for example, position and motion sensors (e.g., compasses, gyroscopes, accelerometers, and/or other devices for monitoring the location, orientation, and movement of device  10 ), may include force sensors, temperature sensors, touch sensors, buttons, capacitive proximity sensors, light-based proximity sensors, other proximity sensors, strain gauges, gas sensors, pressure sensors, moisture sensors, magnetic sensors, and other sensors, may include audio components such as microphones for gathering voice commands and other audio input, and may include speakers for providing audio output (e.g., for providing sound to the left and right ears of a user). If desired, input-output devices  18  may include haptic output devices (e.g., vibrating components), light-emitting diodes and other light sources, and other output components. Circuitry  22  may include wired and wireless communications circuitry that allows device  10  (e.g., control circuitry  20 ) to communicate with external equipment (e.g., remote controls, joysticks and other input controllers, portable electronic devices, computers, displays, etc.) and that allows signals to be conveyed between components (circuitry) at different locations in head-mounted display  10 . 
       FIG. 2  is a cross-sectional side view of display  14  in an illustrative configuration in which display  14  is has structures that allow display  14  to exhibit desired optical properties (e.g., a desired reflectance, desired transmittance, etc.). As shown in  FIG. 2 , display  14  may include display layers  30  and adjustable reflectance and transmittance layer (structures)  32 . Display layers  30  may include an array  34  of pixels  36 . Pixel array  34  may be, for example, an array of organic light-emitting diode pixels, an array of liquid crystal display pixels, or other suitable pixels for displaying images (output light  42 ) to a user such as viewer  44  who is viewing display  14  in direction  46 . 
     Display layers  30  may include one or more layers on top of pixel array  34  such as layers  38  and  40 . Layer  40  may be, for example, a linear polarizer. Linear polarizer  40 , which may sometimes be referred to as forming a portion of layers  32 , may pass light with a first polarization orientation while blocking light with a perpendicular second polarization orientation. 
     In a liquid crystal display configuration for display  14 , layer  40  may be an upper polarizer in the liquid crystal display portion of display  14 . The liquid crystal display portion of display  14  may have an opposing lower polarizer and may have a color filter layer and a thin-film transistor layer that are sandwiched between the upper and lower polarizers. A liquid crystal layer may be interposed between the color filter layer and thin-film transistor layer. In this type of arrangement, layer  38  may be omitted. In an organic light-emitting-diode display configuration for display  14 , layer  40  may be a linear polarizer and layer  38  may be a quarter wave plate, so that layer  40  and layer  38  form a circular polarizer that helps suppress reflections of ambient light from reflective structures in pixel array  34 . If desired, layer  38  may be omitted, layers of adhesive (e.g., pressure sensitive adhesive, liquid adhesive, etc.) and/or other materials may be incorporated into layers  30  (e.g., between layers  40  and  38 , between layers  38  and/or  40  and pixel array  34 , above layer  40 , etc.), and/or other structures may be incorporated into display  14  (e.g., in layer  30  and/or above layer  30 ). 
     Layer  32  may include structures such as reflective polarizers, an adjustable liquid crystal layer (adjustable liquid crystal cell) for adjusting the polarization rotation properties of layer  32 , an adjustable polarizer, and/or other structures for adjusting the reflectance (and light transmission) properties of display  14 . Sections (areas) of layer  32  such as sections  32 T may be individually adjusted. Each section  32 T may have electrodes that receive control signals from control circuitry  20 . During operation, control circuitry  20  may adjust the reflectance and light-transmission properties of each section  32 T by supplying that portion of layer  32  with respective control signals. The reflectance and light transmission sections  32 T may be adjusted in tandem or may be adjusted separately (e.g., so that each of multiple sections  32 T of polarizer  32  exhibits a potentially different reflectance and transmittance). 
     By adjusting pixel array  34 , control circuitry  20  can display desired images on display  14  for viewer  44 . By adjusting layer  32 , control circuitry  20  can place a selected area of display  14  (e.g., the area overlapping displayed images) in a highly transparent state for emitted image light to allow viewer  44  to view light  42  emitted from pixel array  34  associated with desired images content while placing another area of display  14  (e.g., the area not overlapping the displayed images) in a reflective state for ambient light so that this area of display  14  will have a mirror appearance for viewer  44  (e.g., so that ambient light  48  will reflect towards viewer  44  as reflected light  50 ). If desired, control circuitry  20  can place some or all of display  14  in an intermediate (partially reflective state) by supplying one or more sections of layer  32  with appropriate control signals. 
       FIGS. 3 and 4  are cross-sectional side views of an illustrative display with an adjustable reflectance and transmittance layer. As shown in  FIG. 3 , adjustable reflectance and transmittance layer  32  may include liquid crystal layer  64 . Layer  64  may be interposed between transparent electrodes  62  and  66  and may form an adjustable twisted nematic liquid crystal cell. By adjusting the voltages of the signals applied by control circuitry  20  to electrodes  62  and  66 , the amount of rotation of the liquid crystals in layer  64  and therefore the amount of polarization rotation imparted on light traversing layer  64  can be controlled. Electrodes  62  and  66  may be formed from transparent conductive material such as indium tin oxide. Electrode  62  may be formed on layer  60  or other suitable substrate. Electrode  66  may be formed on layer  68  or other suitable substrate. Adjustable (switchable) polarizer  70  may be formed on top of layer  68 , so that layer  68  is interposed between layer  64  and polarizer  70 . 
     In the examples of  FIGS. 3 and 4 , light that is linearly polarized with its electric field oriented parallel to the X axis may be referred to as TM light. Light that is linearly polarized with its electric field oriented parallel to the Y axis (perpendicular to the X axis) may be referred to as TE light. 
     In layer  30 , linear polarizer  40  may have a pass axis that is aligned with the X axis (e.g., the pixel array and other layers of layer  30  may emit image formed from TM polarized light). Reflective polarizers  60  and  68  transmit light that is polarized along a given lateral dimension while reflecting perpendicularly polarized light. In the example of  FIGS. 3 and 4 , reflective polarizer  60  may have a pass axis that is aligned with the X axis and reflective polarizer  68  may have a pass axis that is aligned with the X axis. As a result, reflective polarizers  60  and  68  may reflect TE polarized light and may transmit TM polarized light. Switchable polarizer  70  may have be operable in a first state (sometimes referred to as an off mode) in which polarizer  70  is transparent (transmittance is about 100%) and may be operable in a second state (sometimes referred to as an on mode) in which polarizer  70  transmits TM light (transmittance for TM is about 100%) and absorbs TE light (absorption is about 100%). 
       FIG. 3  illustrates operation of layer  32  in a state in which layer  32  is opaque (transmittance to emitted image light is about zero) and in which layer  32  exhibits a mirror appearance (reflectance of ambient light is about 100%). In this reflective non-transparent state, which may sometimes be referred to as a mirror state, the liquid crystal cell formed from layer  64  is placed in an off state by control circuitry  20 . In this off state, layer  64  rotates TM light to TE light as the light passes through layer  64 . In the configuration of  FIG. 3 , switchable polarizer  70  is placed in an off state by control circuitry  20 . When switchable polarizer  70  is in its off state, polarizer  70  is transparent to both TE and TM light. 
     As shown in  FIG. 3 , light  72  that is emitted from the pixels of layer  30  may be linearly polarized upon passing through linear polarizer  40 . In particular, light  72  may exhibit a TM polarization. TM light  72  may travel outwards towards viewer  44  (upwards in the orientation of  FIG. 3 ) through reflective polarizer  60 , because light  72  is polarized in alignment with the pass axis of reflective polarizer  60 . Liquid crystal layer  64  is in its off state (e.g., applied voltage across electrodes  62  and  66  may be 0 volts), so light  72  is rotated from a TM polarization upon entering layer  64  to a TE polarization upon exiting layer  64 , as illustrated by TM light ray  74  and TE light ray  76 . TE polarized light  76  is reflected downwards as TE polarized light  80  by polarizer  68 , as illustrated by light ray  78 , because the reflective polarizer  68  is configured to reflect TE polarized light. Light  81  that passes through layer  64  is rotated from TE polarization upon entering layer  64  as light  80  to TM polarized light upon exiting layer  64  as light  82 . Because light  82  is TM polarized, light  82  is absorbed by polarizer  40 . Emitted image light from the pixels of layer  30  is therefore not emitted from display  14 , because layer  32  is opaque to emitted light and has a low (zero) transmittance for polarized emitted light  72 . 
     At the same time, layer  30  may be highly reflective to ambient light (e.g., light in the environment surrounding viewer  44  including light from an illuminated face or other body part of viewer  44 ). Ambient light may contain both TE and TM polarized light. Ambient light with a TE polarization such as ambient light  83  may pass through switchable polarizer  70  and may be reflected by reflective polarizer  68 , as illustrated by TE light  84  and  86  of  FIG. 3 . Ambient light with a TM polarization such as ambient light  88 , may pass through layer  70  (which is in a transparent state), as illustrated by TM light  90 . As TM light  90  passes through layer  64 , this light is rotated in polarization by 90° and becomes TE polarized, as illustrated by TE light  92 . Light  92  may be reflected by reflective polarizer  60  to form TE polarized light  96 , as illustrated by light  94 . Upon passing through layer  64  in the upwards (+Z) direction of  FIG. 3 , the polarization of light  96  may be rotated from TE to TM, as illustrated by TM light  98 . Because light  98  is TM polarized, light  98  may pass through reflective polarizer  68 . Light  98  may pass through switchable polarizer  70  and may exit display  14  as reflected TM light  100 , because polarizer  70  is in its off (no absorption) state in the configuration of  FIG. 3 . 
     As the example of  FIG. 3  demonstrates, control circuitry  20  may apply control signals to layer  64  and layer  70  that place layer  64  in a polarization rotating state and that place layer  70  in a non-absorbing state, thereby causing layer  32  to block emitted light from the pixel array of layer  30  and to reflect ambient light. The region of display  14  that is shown in  FIG. 3  will therefore not emit any image light from layers  30  and will have a mirror appearance to viewer  44  (e.g., a reflection of viewer  44  and the environment surrounding viewer  44  will be visible to viewer  44  on display  14 ). Portions of display  14  that are configured in this way may sometimes be referred to as operating in a mirror mode. 
       FIG. 4  illustrates operation of layer  32  in a mode of operation in which layer  32  is a transparent non-reflective state (transmittance to emitted light is about 100% and reflectance of ambient light is about 0%). In the configuration of  FIG. 4 , switchable polarizer  70  is placed in an on state by control circuitry  20 . In the on state, polarizer  70  is transparent to TM light but absorbs and thereby blocks TE light. 
     In this mode of operation, which is illustrated in  FIG. 4 , the liquid crystal cell formed from layer  64  is placed in an on state by control circuitry  20  (the voltage across electrodes  62  and  66  is at an appropriate non-zero level to rotate the liquid crystals of layer  64  into alignment with the Z axis). In the on state, layer  64  allows light to pass without imparting a 90° polarization rotation (light polarization is unchanged upon traversing layer  64 ). Light  102  that is emitted from layer  30  with a TM polarization passes through reflective polarizer  60  and through liquid crystal layer  64  as TM light  104 . After passing through layer  64 , this light passes through layer  68  and layer  70 , as illustrated by TM light  106 . Viewer  44  may view emitted image light such as light  106 . 
     Ambient TE light  108  is absorbed by switchable polarizer  70 , which is in its on (TE absorbing) state. Ambient TM light  110  passes through polarizer  70  and reflective polarizer  68  and, as illustrated by TM light  112  and  114 , traverses layer  64  without being rotated in polarization. TM light  114  that exits layer  64  and enters reflective polarizer  60  is transmitted through polarizer  60  and is absorbed in layer  30  (e.g., by black masking layer structures and other non-reflecting display structures in layer  30 ). 
     A cross-sectional side view of an illustrative switchable polarizer such as polarizer  70  of  FIGS. 3 and 4  is shown in  FIG. 5 . As shown in  FIG. 5 , polarizer  70  may have a guest-host liquid crystal layer such as layer  162  sandwiched between a pair of opposing transparent conductive electrodes (e.g., indium tin oxide electrodes) such as electrodes  158  and  160 . Electrodes  158  and  160  may be formed on transparent substrates such as substrates  150  and  152  (e.g., glass, plastic, etc.). Control circuitry  20  may supply control signals (e.g., control voltages) to electrodes  158  and  160  via respective terminals  156  and  154 . Layer  162  may include liquid crystals  164  (sometimes referred to as liquid crystal molecules or host molecules) and dichroic dye  166  (sometimes referred to as guest molecules or dichroic dye molecules). The rotation of dye  166 , which serves as polarizing material, tracks the rotation of liquid crystals  164 . The amount of rotation of liquid crystals  164  may be controlled by the control signals from circuitry  20 . The corresponding rotation of molecules  166  and the polarization state of polarizer  70  may therefore be adjusted dynamically by control circuitry  20  by applying signals to terminals  156  and  154 . For example, control circuitry  20  can place polarizer  70  in an off state in which liquid crystals  164  and dye molecules  166  are oriented along the Z axis (as shown in  FIG. 5 ) and in which polarizer  70  transmits both TE and TM light or can place polarizer  70  in an on state in which the longitudinal axes of liquid crystals  164  and dye molecules  166  are horizontally aligned (e.g., along the Y axis) so that TM light is transmitted while TE light is absorbed. 
     In the illustrative configuration of  FIG. 6 , display  14  has a reflective polarizer (e.g., a fixed reflective polarizer) such as reflective polarizer  170 . Reflective polarizer  170  may be formed on top of layer  30  and may reflect light that is TE polarized. Polarizer  40  and reflective polarizer  170  may each have a pass axis aligned with the X-axis of  FIG. 6 . With this configuration, emitted light  172  from pixel array  34  in layer  30  that has a TM polarization may pass through polarizers  40  and  170  and may be viewed by viewer  44 . Emitted light from layer  30  with TE polarization may be absorbed by polarizers  40  and  170 . The transmittance of display  14  for emitted light from pixel array  34  is therefore 50%. Ambient light  174  includes TM light  176  and TE light  178 . Ambient light such as TM light  176  may pass through polarizers  170  and  40  and may be absorbed by opaque masking layer structures (e.g., black masking layer material) and other opaque structures in pixel array  34 . Light  176  will therefore not be reflected from display  14 . Ambient light such as TE light  178  may be reflected by polarizer  170  as reflected ambient light  180 . Display  14  of  FIG. 6  therefore may exhibit a 50% transmission for emitted image light and a 50% (partial mirror) reflectance for ambient light. 
     To provide an enhance reflectance value (e.g., to an amount greater than 50%, greater than 60%, greater than 70%, or other elevated value), multiple fixed reflective polarizers may be incorporated into display  14  and may have pass axes that are oriented at non-zero angles with respect to each other. Consider, as an example, the illustrative configuration of  FIG. 7 . In this example, layer  30  includes linear polarizer  40  and pixel array  34 . Optional quarter wave plate  38  may, if desired, be interposed between layer  34  and layer  40 . Layers  200 ,  202 , and  204  may be formed on top of polarizer  40 . Layers  200  and  204  may be reflective polarizers. Layer  202  may be an adhesive layer and/or other layer(s) of clear material (e.g., polymer, polymer adhesive, etc.). Layer  202  may include, for example, pressure sensitive adhesive, cured liquid optically clear adhesive, a polymer film such as a layer of tri-acetyl cellulose (TAC) or other polymer, a TAC layer or other layer that is coated on one or both sides with pressure sensitive adhesive or other adhesive, etc. 
     Linear polarizer  40  may have a pass axis that is aligned with the X axis of  FIG. 7 , so that polarizer  40  passes TM polarized light and blocks TE light. Reflective polarizer  200  may also have a pass axis that is aligned parallel to the X axis. Reflective polarizer  200  may therefore pass light that has a TM polarization and may reflect TE polarized light. Layer  202  may be clear and may therefore pass light of both TM and TE polarizations. The thickness of layer  202  may be sufficient to reduce interference effects that might otherwise arise from reflections between the parallel surfaces of polarizers  200  and  204 . As an example, the thickness of layer  202  may be 70-90 microns, 50-110 microns, more than 30 microns, more than 50 microns, more than 70 microns, less than 200 microns, or other suitable thickness that is sufficient to disrupt coherence and interference effects in the light that is reflected in the adhesive-filled gap between polarizers  200  and  204 . 
     Reflective polarizer  204  may have a pass axis that is oriented at an angle A with respect to the X axis and therefore is oriented at angle A with respect to the to the pass axis of reflective polarizer  200 . In a configuration in which the value of angle A is 0°, display  14  will exhibit 50% ambient light reflectance and 100% emitted light transmittance. In a configuration in which the value of angle A is 90°, display  14  will exhibit 0% transmittance for emitted light and 50% reflectance. At angles A between 0° and 90°, display  14  will exhibit enhanced emitted light transmittance and enhanced ambient light reflectance. As an example, if A is 50°, display  14  may exhibit a mirror-like ambient light reflectance level of 70% and may exhibit an emitted light transmittance of 60%. Other non-zero angles A may be used in display  14  if desired (e.g., A may be 30°-70°, more than 45°, less than 80°, or other suitable angle). Displays such as display  14  may provide a fixed mirror-like reflectivity (e.g., 70% ambient light reflectivity or other suitable elevated value) while exhibiting satisfactory light transmittance for image light emitted by the pixels of pixel array  34 . 
     In configurations in which display  14  has multiple individually controllable areas, different portions of display  14  may dynamically be placed in either a content-displaying state or a mirror state. Consider, as an example, illustrative display  14  of  FIG. 8 . Display  14  may have structures of the type shown in  FIG. 2  that allow portions  32 T of layer  32  (and therefore display  14 ) to be placed in either a transparent non-reflective state in which image transmission is elevated and ambient light reflection is suppressed or a reflective non-transparent state in which image transmission is blocked and ambient light reflection is elevated. 
     As shown in  FIG. 8 , for example, display  14  may have an array of individually adjustable areas  32 T (sometimes referred to as tiles or subregions of display  14 ). Some areas  32 T such as the areas labeled “C” in  FIG. 8  may be placed in a content-displaying state and may display content for a user. The content may include, for example, text, graphics, video, still images, or other image content. Other areas  32 T such as the areas labeled “M” in  FIG. 8  may be placed in a mirror state. Emitted light transmission may be low in mirror mode areas M, but reflective is high, so areas M may appear to a user as if they were mirrors (e.g., no content may be displayed and only ambient light reflections may be visible). 
     Control circuitry  20  may use information from tracking system  16  to reconfigure display  14  dynamically, as shown in the illustrative top views of display  14  in  FIGS. 9 and 10 . In response to detecting that viewer  44  (e.g., the head of a user) is in front of a middle section of display  14  as shown in  FIG. 9 , for example, control circuitry  20  may configure strips (area C) of the surface of display  14  along the left and right edges of display  14  to display content while placing the middle section in front of viewer  44  in mirror mode (mirror mode area M). In this configuration, a reflection of viewer  44  may be visible to viewer  44  in the mirror formed by mirror mode area M and text, video, and/or other images may be visible to the viewer in content-displaying area C. 
     When viewer  44  moves to the left side of display  14  as shown in  FIG. 10 , control circuitry  20  can detect the new position of viewer  44  using tracking system  16  and can dynamically reconfigure display  14  by moving mirror mode area M and content-displaying area C with respect to each other in response to the new position gathered with system  16 . For example, mirror area M may be repositioned in front of the viewer&#39;s new location to ensure that the viewer&#39;s reflection is still visible to the viewer while content may be moved to only the right side of display  14  (see, e.g., content area C on the right-hand portion of display  14  in  FIG. 10 ). In this way, control circuitry  20  may dynamically reconfigure the locations of the mirror and content-displaying portions of display  14  based on viewer position or other information from sensor systems such as tracking system  16  to ensure that the viewer&#39;s reflection is always visible to the viewer and is not obscured by the presence of non-reflective content regions. At the same time, the dynamic reconfiguration of the mirror may ensure that desired content remains visible to the user. 
       FIG. 11  is a perspective view of an illustrative electronic device with a display that is being viewed by a viewer. Tracking system  16  (e.g., a gaze tracking system) may be embedded behind a portion of display  14  or may be located elsewhere in device  10 . During operation, system  16  may gather information on the viewer&#39;s point-of-gaze. Point-of-gaze information can be used in forming input commands during operation of device  10 . Consider, as an example, a scenario in which portion  220  of display  14  is placed in mirror mode (see, e.g., mirror region M of  FIG. 11 ). Mirror region M may be large and may cover most of display  14  to allow viewer reflections to be easily viewed by viewer  44 . When the viewer desires to view weather, sports scores, news, calendar information, and/or other content, there may initially be insufficient content displaying area available on the surface of display  14 . If the viewer desires to direct device  10  to enlarge the amount of content area on display  14 , the viewer may look at an icon or other information on a particular portion of display  14 . System  16  may detect that the viewer&#39;s point-of-gaze is dwelling on the icon and may take appropriate action such as enlarging the amount of area on display  14  that is used for displaying content (e.g., some of mirror region  220  may be converted into a content-displaying region). 
     In the example of  FIG. 11 , viewer  44  is looking at display  14  in two different directions. Initially, the viewer&#39;s point-of-gaze is directed towards mirror region  220  (see, e.g., point-of-gaze  46 A). When the viewer&#39;s gaze is oriented in this way, a reflection of the viewer will be visible to the viewer. If the viewer desires to view content, the viewer may shift the point-of-gaze towards an icon or other information in content-displaying region  222  (see, e.g., point-of-gaze  46 B). Control circuitry  20  can use information from tracking system  16  to detect when the viewer&#39;s point-of-gaze is directed towards region  222  (or other appropriate area of display  14 ) for more than a predetermined amount of time and can conclude that the viewer is commanding device  10  to convert some or all of mirror region M into a content-displaying region. Control circuitry  20  can then dynamically reconfigure display  14  to enlarge the content-displaying portion of display  14  relative to the mirror portion of display  14  accordingly. 
       FIG. 12  is a diagram showing how tracking system  16  can gather vergence information on viewer  44 . The gathered vergence information from the eyes of viewer  44  can be used as user input (e.g., a command to dynamically reconfigure display  14  to enlarge the amount of display  14  that is used for displaying content relative to the amount of display  14  that is used as a mirror). 
     Vergence is the movement of eyes  44 E towards or away from each other as viewer  44  looks at objects that are respectively closer or farther away from the viewer&#39;s location. Consider, as an example, a scenario in which a central portion of display  14  is in mirror mode. In this scenario, viewer  44  may be viewing a reflection of the viewer (e.g., virtual image  44 VI of viewer  44 ) in the mirror formed by display  14 . When viewing virtual image  44 VI, the viewer&#39;s left eye  44 E will be viewing point  246  on virtual image  44 VI along viewing path  244 L and the viewer&#39;s right eye  44 E will be viewing point  246  on virtual image  44 VI along viewing path  244 R. System  16  can detect the orientation (direction of view) of each eye  44 E (e.g., by using a gaze tracking system to process glint information from images of viewer eyes  44 E). The orientation of each eye  44 E (e.g., vergence information such as the directions of paths  244 L and  244 R indicating that the viewer is focusing eyes  44 E on point  246  of virtual image  44 VI) may be used in determining that the viewer is viewing a reflection of the viewer in the mirror portion of display  14 . 
     While the viewer is viewing a reflection such as virtual image  44 VI, the viewer may desire to invoke a more content-rich mode of operation. With one illustrative configuration, the viewer may focus on the surface of display  14  (see, e.g., point  242 ) to direct control circuitry  20  to display more content. System  16  may measure the resulting vergence of the viewer&#39;s eyes. For example, when a viewer is looking at point  242  (e.g., an icon or a portion of display  14 , a frame associated with display  14 , or other point that is located at a distance that is closer to viewer  44  than virtual image  44 VI), system  16  may detect that the viewer&#39;s left eye  44 E is viewing point  242  along viewing path  240 L and that the viewer&#39;s right eye  44 E is viewing point  242  along viewing path  240 R. The vergence (angular spread B 2 ) associated with looking at point  242  is different than the vergence (angular spread B 1 ) associated with looking at point  246  (virtual image  44 VI) and this difference can be used to sense when a viewer is no longer focusing on the viewer&#39;s reflection. In response to measured vergence of the viewer, control circuitry  20  may take actions such as displaying content over the central portion of display  14 , over all of display  14 , or over other portions of display  14  (e.g., the left and/or right sides of display  14 ), or may take other suitable action. 
     If desired, display  14  (e.g., pixel array  34 ) may be an autostereoscopic display that is capable of displaying images at multiple image planes. Display  14  may, as an example, display images at an image plane that is aligned with virtual image  44 VI of viewer  44  (e.g., so that augmented reality content may be displayed in a location that is aligned with virtual image  44 VI and/or that overlaps virtual image  44 VI). For example, clothing templates, images of sample hairstyles, and other augmented reality images may be displayed at an image plane that is aligned with virtual image  44 VI. These augmented reality items may overlap and/or be aligned with some or all of virtual image  44 VI so that viewer  44  can view both the viewer&#39;s reflection and the associated augmented reality content in the same image plane. During operation, control circuitry  20  can adjust the image plane of displayed content based on vergence information from system  16  and/or other data gathered with system  16 , input-output devices  18 , and/or other input-output circuitry  22 . 
     Tracking system  16  may use camera(s), proximity sensor(s), and/or other sensors to monitor viewer gestures (e.g., hand gestures or other gesture input). Gesture input may be used to direct control circuitry  20  to reconfigure the mirror and content displaying portions of display  14  and/or to perform other operations. For example, control circuitry  20  may determine with system  16  that a viewer has made a left swipe hand gesture. In response to the left swipe, content that was previously presented in a strip along the right-hand side of display  14  may be moved from right to left across display  14  and may be presented next to previously displayed content on the left-hand side of display  14 . If desired, voice commands and/or other input may be gathered by circuitry  22  and used by control circuitry  20  in controlling the operation of device  10 . 
     In general, any suitable viewer (user) input can be provided to device  10  to reconfigure display  14  and/or take other actions. The user input may be gatherer using tracking system  16 , input-output devices  18 , and/or other input-output circuitry  22 . Viewer input may include head tracking input (e.g., information on the position of the head of viewer  44 ), may include gaze tracking information (e.g., information on the point-of-gaze of viewer  44 , the amount of time viewer  44  maintains any given point-of-gaze, information on the speed and direction with which the viewer&#39;s point-of-gaze moves across display  14 , etc.), may include vergence information, may include viewer gesture information, may include voice commands, may include button press information, key strokes, touch sensor input, proximity sensor input, etc. 
     System  16  may include cameras for gesture tracking, eye tracking, head position measurements, and other input gathering operations. If desired, one or more cameras in display  14  or elsewhere in device  10  may capture images of viewer  44  while viewer  44  is looking at virtual image (viewer reflection)  44 VI. Control circuitry  20  may be configured to capture this type of self-portrait image (“selfie”) in response to determining that the viewers head is in a particular position relative to display  14 , in response to detecting that the viewer&#39;s point-of-gaze is fixed or is directed at a particular on-screen location, and/or in response to other input from input-output circuitry  22 . If desired, circuitry  22  may direct circuitry  20  to capture the self-portrait image of viewer  44  in response to receipt of a wirelessly received command from a cellular telephone, remote control, or other wireless portable electronic device being held and operated by viewer  44  or other operator of device  10 . 
     Content-displaying regions C on display  14  may be used for displaying notifications, messages, calendar events, moving and still content, content with text, content with text and embedded video, and/or other images. If desired, input-output circuitry  22  may be used to gather information on a viewer&#39;s habits (amount of movement, wake and sleep times, heart rate, etc.). Input-output circuitry  22  may include heart-rate monitoring circuitry (e.g., a camera that produces images that may be processed by circuitry  20  to extract heart rate information, a light-based heart-rate sensor with a light source and corresponding detector, etc.), information on heart rate measurements from a viewer&#39;s wristwatch may be conveyed to control circuitry  20  wirelessly, and/or other information may be used to gather information on the habits and health of a viewer (e.g., system  16  may gather statistics on a viewer&#39;s eye movements to help diagnose potential health issues, to determine whether the viewer is alert or is tired, and/or gather other viewer biometric and/or behavioral information). Display  14  may be touch sensitive (e.g., input-output circuitry  22  may include a touch sensor overlapping display  14 ) and may gather touch input from a viewer (e.g., a viewer may tap on displayed items of interest on display  14 ). Touch sensor input and/or other input from input-output circuitry  22  may be used to control home automation equipment (lights, motorized blinds, audio/video equipment, heating and air-conditioning equipment, etc.). For example, a user may provide gaze input, gesture input, voice commands, and/or other input to device  10  that is gathered using circuitry  22  and used to direct control circuitry  20  to take appropriate action (e.g., adjusting light levels, opening blinds, adjusting media playback functions, changing thermostat settings, etc.). 
     Illustrative operations involved in operating device  10  are shown in  FIG. 13 . 
     At step  280 , device  10  may gather information from viewer  44 . As an example, input-output circuitry  22  (e.g., tracking system  16 , sensors and/or other input-output devices  18 , etc.) may gather head position information, point-of-gaze information (point-of-gaze location, point-of-gaze dwell time and movement information, etc.), gestures (e.g., hand gestures), voice command input, biometric information (facial recognition information), vergence information, health information (directly measured and/or relayed heart rate measurement, respiration rate information, eye movement statistics, etc.), and/or other information on viewer  44 , the operating environment of device  10  and/or other information. 
     Control circuitry  20  may take suitable actions based on this information at step  282 . For example, control circuitry  20  may use information on the position of the head of viewer  44  to reconfigure the mirror and content-displaying portions of display  14 , may use point-of-gaze information, gestures, voice commands, biometric and/or health information, button press information, vergence information, and/or other viewer input and/or environmental data to adjust which content is displayed in the content-displaying portions of display  14 , to add or remove calendar entries, to adjust settings in a messaging application, to set or clear reminders, to capture self-portraits and/or other images, and/or to perform other tasks. 
     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: 20171207
Publication Date: 20191203
Grant Date: 20191203
Priority Date: 20161209
Inventors: JOHNSON, PAUL V.
CHEN, YUAN
POSNER, BRYAN W.
CHEN, CHENG
TAI, CHIA HSUAN
WU, JIAYING
CAO, ROBERT Y.
FAN JIANG, SHIH-CHYUAN
CHANG, SHIH-WEI
LI, XIAOKAI
GE, ZHIBING
MATHEW, DINESH C.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/133536", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/011", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/0063", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133536", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/0045", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/011", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13475", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/0063", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133536", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/0045", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/013", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/01", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13475", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13475", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/01", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 62487790