PATENT DOCUMENT

Publication Number: US-12213267-B2
Application Number: US-202016784833-A
Country: US
Kind Code: B2

Title: Electronic devices having folding expandable displays

Abstract:
An electronic device has a foldable display. First and second portions of an electronic device housing for the device may be joined using hinge structures. A flexible display may overlap the first housing portion, the hinge structures, and the second housing portion. A layer such as a layer of sheet metal may be used in supporting the display and may overlap the hinge structures. The hinge structures may include gear teeth, belts, and/or other movement synchronization structures. The hinge structures may include members that move relative to each other during bending. The moving members may include bars and links with opposing curved bearing surfaces. Stop surfaces may prevent excessive rotation of the bars and links with respect to each other. The links may rotate about pivot points that lie within the thickness of the display without the hinge structure living within the thickness of the display.

Claims:
What is claimed is: 
     
       1. A foldable electronic device, comprising:
 a housing having a first housing portion and a second housing portion coupled with hinge structures, wherein the hinge structures include links and bars configured to rotate relative to each other about respective pivot points; and 
 a flexible display that overlaps the first housing portion, the hinge structures, and the second housing portion, wherein the pivot points define a reduced stress plane that lies within the flexible display, the reduced stress plane is a neutral stress plane, the housing and the flexible display are movable between an unfolded state and a folded state, the links and the bars are configured to contact the flexible display in the unfolded state, and the bars are configured to contact the flexible display without the links in the folded state. 
 
     
     
       2. The foldable electronic device defined in  claim 1  wherein the flexible display comprises an organic light-emitting diode display having a layer of pixels. 
     
     
       3. The foldable electronic device defined in  claim 2  further comprising a flexible sheet of metal between the flexible display and the hinge structures. 
     
     
       4. The foldable electronic device defined in  claim 1  wherein the links and bars comprise stop surfaces. 
     
     
       5. The foldable electronic device defined in  claim 1  wherein the links and the bars comprise opposing curved bearing surfaces. 
     
     
       6. The foldable electronic device defined in  claim 1  wherein the links have convex surfaces that face the flexible display. 
     
     
       7. A foldable electronic device, comprising:
 a housing having a first housing portion and having a second housing portion coupled at hinge structures, wherein the hinge structures include a plurality of links and a plurality of bars, wherein the links and bars have opposing curved bearing surfaces, the curved bearing surfaces of the bars have a first curvature, the bars have convex outer surfaces opposite the curved bearing surfaces of the bars, wherein the convex outer surfaces have a second curvature that is different from the first curvature, and each link is configured to rotate about a pivot point relative to an associated one of the bars; and 
 a flexible display that overlaps the first housing portion, the convex outer surfaces of the bars in the hinge structures, and the second housing portion, wherein the pivot points define a reduced stress plane that lies within the flexible display, the reduced stress plane is a neutral stress plane, the housing and the flexible display are movable between an unfolded state and a folded state, the links and the bars are configured to contact the flexible display in the unfolded state, and the bars are configured to contact the flexible display without the links in the folded state. 
 
     
     
       8. The foldable electronic device defined in  claim 7  wherein the flexible display comprises an array of organic light-emitting diode pixels and wherein the reduced stress plane lies within the flexible display. 
     
     
       9. The foldable electronic device defined in  claim 7  wherein each of the bars has a stop surface and wherein each of the links has an opposing stop surface. 
     
     
       10. The foldable electronic device defined in  claim 7  wherein, when the first and second housing portions are folded together, the flexible display is folded outwardly and a bent portion of the flexible display is supported on an outwardly facing surface of the hinge structures. 
     
     
       11. The foldable electronic device defined in  claim 7  wherein each bar has a first portion and a second portion joined by a post and wherein each link has an opening through which the post protrudes. 
     
     
       12. The foldable electronic device defined in  claim 11  wherein the posts have stop surfaces that are configured to contact corresponding side surfaces of the openings and thereby stop bending of the hinge structures as the first and second housing portions are folded together. 
     
     
       13. A foldable electronic device, comprising:
 a housing having a first housing portion and a second housing portion coupled with hinge structures, wherein the hinge structures include links and bars configured to rotate relative to each other about respective pivot points; and 
 a flexible display that overlaps the first housing portion, the hinge structures, and the second housing portion, the housing and the flexible display are movable between an unfolded state and a folded state, the links and the bars are configured to contact the flexible display in the unfolded state, and the bars are configured to contact the flexible display without the links in the folded state. 
 
     
     
       14. The foldable electronic device defined in  claim 13  wherein the bars comprise convex surfaces that support the flexible display in the unfolded state. 
     
     
       15. The foldable electronic device defined in  claim 14  wherein the links comprise additional convex surfaces. 
     
     
       16. The foldable electronic device defined in  claim 14  wherein the links and the bars comprise opposing curved bearing surfaces. 
     
     
       17. The foldable electronic device defined in  claim 16  wherein the links and the bars are configured to rotate with respect to each other about the respective pivot points along the opposing curved bearing surfaces. 
     
     
       18. The foldable electronic device defined in  claim 13 , wherein the flexible display has a neutral stress plane, and the respective pivot points are within the neutral stress plane.

Description:
This application claims the benefit of provisional patent application No. 62/853,642, filed May 28, 2019, 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. A touch screen display may be used in a cellular telephone or other portable device to display information for a user and to gather user input. 
     If care is not taken, a display may not offer sufficient screen real estate to display information of interest to a user. At the same time, it can be difficult to enlarge the size of electronic devices too much to accommodate larger displays, because this can make devices too bulky. 
     SUMMARY 
     An electronic device may have a foldable display supported by a foldable electronic device housing. First and second portions of the electronic device housing may be joined using hinge structures. The electronic device may have a flexible display such as an organic light-emitting diode display. The flexible display may overlap the first housing portion, the hinge structures, and the second housing portion. A flexible supporting layer such as a layer of sheet metal may be used in supporting the display and may overlap the hinge structures. 
     The hinge structures may include members that are configured to move relative to each other as the hinge structures are bent. In some configurations, hinge structures for the device include gear teeth, belts, and/or other movement synchronization structures. The moving members in the hinge structures may include bars and links with opposing curved bearing surfaces. Stop surfaces may prevent excessive rotation of the bars and links with respect to each other. 
     The bars and links or other moving members in the hinge structures may rotate relative to each other about virtual pivot points that lie outside of the hinge structures. The pivot points may establish a reduced stress plane (e.g., a neutral stress plane or approximation of a neutral stress plane). The reduced stress plane may lie within the flexible display. This may help reduce stress on the pixels or other brittle layers of the display module as the display is bent. 
     In some configurations, the hinge structures may include a sliding hinge pin support plate. A hinge pin that passes through the second portion of the housing may be supported by the sliding hinge pin support plate. The hinge pin allows the second portion of the housing to rotate relative to the plate and first housing portion. When the first and second housing portions are folded together, the support plate may slide relative to the first housing portion, thereby moving the hinge pin relative to the first housing portion. This helps to ensure that links in the hinge structures are smoothly wrapped around a curved surface on the second housing surface as the device is folded. A bent portion of the display may rest on an outwardly facing surface of the hinge structures when the display is folded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG.  2    is a schematic diagram of an illustrative electronic device in accordance with an embodiment. 
         FIG.  3    is a cross-sectional side view of an illustrative electronic device in accordance with an embodiment. 
         FIG.  4    is side view of an illustrative electronic device with a foldable display in accordance with an embodiment. 
         FIG.  5    is a side view of an illustrative electronic device with a sliding display in accordance with an embodiment. 
         FIG.  6    is a side view of an illustrative electronic device with a scrolling display in accordance with an embodiment. 
         FIG.  7    is a cross-sectional side view of an illustrative flexible display structure in accordance with an embodiment. 
         FIG.  8    is a cross-sectional side view of an illustrative electronic device with a folding display in accordance with an embodiment. 
         FIG.  9    is a cross-sectional side view of illustrative layers in a flexible display in accordance with an embodiment. 
         FIG.  10    is a cross-sectional side view of illustrative layers in a protective layer for a display in accordance with an embodiment. 
         FIG.  11    is a top view of a layer of an illustrative display showing how isolated columns of adhesive may be used in coupling sublayers in the layer together in accordance with an embodiment. 
         FIGS.  12  and  13    are cross-sectional side views of portions of a flexible display with interlocking sliding structures coupled between adjacent display layers in accordance with an embodiment. 
         FIG.  14    is a cross-sectional side view of an illustrative electronic device with a folded display in an unexpanded configuration in accordance with an embodiment. 
         FIG.  15    is a cross-sectional side view of the illustrative electronic device of  FIG.  14    is an expanded configuration in accordance with an embodiment. 
         FIG.  16    is a cross-sectional side view of an illustrative flexible device having a segmented hinge in accordance with an embodiment. 
         FIG.  17    is a cross-sectional side view of the illustrative flexible device of  FIG.  16    in a folded configuration in accordance with an embodiment. 
         FIGS.  18  and  19    are cross-sectional side views of an illustrative flexible display showing how a reduced stress plane may be configured to coincide with an interior portion of the flexible display in alignment with a layer of thin-film pixels or other brittle display layers in accordance with an embodiment. 
         FIG.  20    is a cross-sectional side view of an illustrative electronic device with multilink hinge structures supporting a flexible display in accordance with an embodiment. 
         FIG.  21    is a perspective view of an illustrative foldable electronic device with a segmented hinge in accordance with an embodiment. 
         FIG.  22    is a perspective view of the illustrative device of  FIG.  21    in a configuration in which the hinge has been bent at a right angle in accordance with an embodiment. 
         FIG.  23    is a perspective view of the illustrative device of  FIG.  21    in a configuration in which the hinge has been bent by 180° in accordance with an embodiment. 
         FIG.  24    is a side view of an illustrative foldable electronic device with a folding mechanism that synchronizes movement of first and second hinged housing portions in accordance with an embodiment. 
         FIG.  25    is a side view of synchronized hinge structures for use in an electronic device such as the electronic device of  FIG.  24    in accordance with an embodiment. 
         FIG.  26    is a side view of illustrative pulley mechanisms that may be used to help synchronize movement between hinge structures in an electronic device such as the electronic device of  FIG.  24    in accordance with an embodiment. 
         FIG.  27    is a cross-sectional side view of an illustrative friction mechanism for a hinge in accordance with an embodiment. 
         FIG.  28    is a cross-sectional side view of an illustrative detent mechanism for a hinge in accordance with an embodiment. 
         FIG.  29    is a cross-sectional side view of an illustrative foldable device hinge mechanism with a layer of flexible material such as a spring metal sheet or other flexible sheet to help synchronize movement of respective foldable device housing portions while supporting a flexible display in accordance with an embodiment. 
         FIGS.  30 ,  31 , and  32    are side views of illustrative profiles of prestressed layers of flexible metal in accordance with an embodiment. 
         FIG.  33    is top view of an illustrative pattern of flexibility-enhancement openings for the layer of flexible material of  FIG.  29    in accordance with an embodiment. 
         FIG.  34    is a side view of an illustrative movable hinge plate for a foldable device in accordance with an embodiment. 
         FIG.  35    is a side view of an illustrative foldable electronic device that includes the movable hinge plate of  FIG.  34    in accordance with an embodiment. 
         FIG.  36    is a perspective view of a portion of the illustrative foldable electronic device of  FIG.  35    showing how the hinge structures of the device may include the movable hinge plate and a set of hinge links in accordance with an embodiment. 
         FIG.  37    is a perspective view of the device of  FIG.  36    in a folded configuration in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device may have a display. The display may have an array of pixels for displaying images for a user. The display may be an organic light-emitting diode display, a micro-light-emitting diode display formed from an array of crystalline semiconductor light-emitting diode dies, and/or may be any other suitable display. A two-dimensional touch sensor such as a capacitive touch sensor or other touch sensor may be incorporated into the display (e.g., by forming capacitive sensor electrodes from thin-film display circuitry) and/or a touch sensor layer may be laminated to an array of pixels in the display. 
     The display of the electronic device may be operated in unexpanded and expanded configurations. In the unexpanded configuration, portability of the device is enhanced. In the expanded configuration, viewable display area is increased, making it easier to provide touch input and to view images on the display. 
     A perspective view of an illustrative electronic device of the type that may include an expandable display is shown in  FIG.  1   . Device  10  may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a desktop computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a wristband device, a pendant device, a headphone or earpiece device, a head-mounted device such as glasses, goggles, a helmet, or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which equipment is mounted in a kiosk, in an automobile, airplane, or other vehicle, a removable external case for electronic equipment, an accessory such as a remote control, computer mouse, track pad, wireless or wired keyboard, or other accessory, and/or equipment that implements the functionality of two or more of these devices. In the illustrative configuration of  FIG.  1   , device  10  is a portable electronic device such as a cellular telephone or tablet. This configuration may sometimes be described herein as an example. 
     As shown in  FIG.  1   , device  10  may have a housing such as housing  12 . Housing  12  may be formed from materials such as polymer, glass, metal, crystalline materials such as sapphire, ceramic, fabric, foam, wood, other materials, and/or combinations of these materials. Device  10  may have any suitable shape. In the example of  FIG.  1   , device  10  has front face F, opposing rear face R, and sidewall portions (sidewalls) W. Portions W may be formed as extensions of the housing structures on front face F, rear face R, and/or may be formed using one or more separate sidewall members (as examples). Sidewall structures may be planar (e.g., to form vertical sidewalls extending between front F and rear R) and/or may have curved cross-sectional profiles. Input-output devices such as one or more buttons may be mounted on housing  12  (e.g., on sidewall portions W). 
     Device  10  may have one or more displays such as display  14 . In the example of  FIG.  1   , display  14  covers front face F. Display  14  may also be mounted on other portions of device  10 . For example, one or more displays such as display  14  may cover all of front face F, part of front face F, some or all of rear face R, and/or some or all of sidewalls W. In some configurations, some or all of display  14  may be covered with flexible or rigid transparent members that serve as protective display cover layers. Such transparent display cover layer structures, which may sometimes be referred to as housing structures, may overlap at least some of display  14  and may serve as a display cover layer. If desired, transparent thin-film structures may serve as protective display layers (e.g., scratch-resistance layers, oleophobic anti-smudge coating layers, etc.). 
     Display  14  may have a planar shape, a shape with a curved cross-sectional profile, or other suitable shape. In the example of  FIG.  1   , front face F has a planar shape and lies in the X-Y plane. Display  14  may have a rectangular footprint (outline when viewed from above) or other suitable footprint. Device  10  is elongated along longitudinal axis  56  (e.g., parallel to the Y axis of  FIG.  1   ). The thickness of device  10  in dimension Z, may be less than the width of device  10  in dimension X and less than the length of device  10  in dimension Y (as an example). 
     To help accommodate a user&#39;s desire for compactness while accommodating a user&#39;s desire for large amounts of display real estate, device  10  can have structures that allow the shape and size of device  10  and display  14  to be adjusted. In particular, device  10  may have a display and associated housing structures that support folding motions, sliding motions, scrolling motions, and/or other behavior that allows device  10  to be adjusted during use. 
     When compact size is desired, device  10  can be adjusted to be compact. Device  10  and display  14  may, as an example, be folded inwardly or outwardly about bend axis  58 . As another example, sliding or scrolling display structures can be retracted so that device size is minimized. 
     When a large screen size is desired, device  10  and display  14  can be unfolded (in a configuration in which device  10  is foldable) or display  14  can be expanded laterally in one or more directions such as direction  52  (parallel to longitudinal axis  56 ) or direction  54  (e.g., a lateral direction that is perpendicular to longitudinal axis  56  and perpendicular to the thickness of device  10 ). Device  10  and display  14  may, for example, be expanded by sliding portions of device  10  (and display  14 ) along axis  56  or axis  58  or by unscrolling a scrolled flexible display in direction  52  or direction  54 . 
     When expanded, display  14  exhibits an expanded viewable area. In particular, the portion of display  14  that is viewable by a user of device  10  when device  10  is expanded (sometimes referred to as the expanded viewable area of display  14 ) is larger than the unexpanded viewable area of display  14  that is presented to a user of device  10  when device  10  is unexpanded. In general, device  10  may use any suitable arrangement that allows display and/or device size and/or shape to be adjusted (e.g., between a first configuration such as an unexpanded viewable area configuration in which a first amount of display  14  is visible to a user viewing the front face of device  10  or other side of device  10  and a second configuration such as an expanded viewable area configuration in which a second amount of display  14  that is greater than the first amount is visible to a user viewing the front face of device  10  or other side of device  10 ). These arrangements may exhibit inward and/or outward folding, scrolling, sliding, and/or other housing and display movements as device  10  and display  14  are transitioned between unexpanded and expanded states. 
     A schematic diagram of an illustrative electronic device is shown in  FIG.  2   . As shown in  FIG.  2   , device  10  may include control circuitry  30 , communications circuitry  32 , and input-output devices  34 . 
     Control circuitry  30  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as 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  30  may be used to gather input from sensors and other input devices and may be used to control output devices. The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors and other wireless communications circuits, power management units, audio chips, application specific integrated circuits, etc. 
     To support communications between device  10  and external electronic equipment, control circuitry  30  may communicate using communications circuitry  32 . Communications circuitry  32  may include antennas, radio-frequency transceiver circuitry, and other wireless communications circuitry and/or wired communications circuitry. Circuitry  32 , which may sometimes be referred to as control circuitry and/or control and communications circuitry, may, for example, support wireless communications using wireless local area network links, near-field communications links, cellular telephone links, millimeter wave links, and/or other wireless communications paths. 
     Input-output devices  34  may be used in gathering user input, in gathering information on the environment surrounding the user, and/or in providing a user with output. 
     Display  14  of input-output devices  34  has an array of pixels for displaying images to users. Display  14  may be a light-emitting diode display (e.g., an organic light-emitting diode or a display with a pixel array having light-emitting diodes formed from crystalline semiconductor dies), an electrophoretic display, a liquid crystal display, or other display. Display  14  may include a two-dimensional capacitive touch sensor or other touch sensor for gathering touch input. Display  14  may have a substrate formed from a flexible dielectric (e.g., a sheet of polyimide or other bendable polymer layer) and/or may have rigid substrate structures. Flexible display arrangements may be used to provide display  14  with the ability to alter size and shape by folding, scrolling, sliding, etc. If desired, some or all of display  14  may include rigid (non-flexible) display structures. 
     Devices  34  may include sensors  36 . Sensors  36  may include force sensors (e.g., strain gauges, capacitive force sensors, resistive force sensors, etc.), audio sensors such as microphones, capacitive touch sensors, capacitive proximity sensors, non-capacitive touch sensors, ultrasonic sensors, sensors for detecting position, orientation, and/or motion (e.g., accelerometers, magnetic sensors such as compass sensors, gyroscopes, and/or inertial measurement units that contain some or all of these sensors), muscle activity sensors (EMG), heart rate sensors, electrocardiogram sensors, and other biometric sensors, radio-frequency sensors (e.g., radar and other ranging and positioning sensors), humidity sensors, moisture sensors, and/or other sensors. 
     Sensors  36  and other input-output devices  34  may include optical components such as light-emitting diodes (e.g., for camera flash or other blanket illumination, etc.), lasers such as vertical cavity surface emitting lasers and other laser diodes, laser components that emit multiple parallel laser beams (e.g., for three-dimensional sensing), lamps, and light sensing components such as photodetectors and digital image sensors. For example, sensors  36  in devices  34  may include optical sensors such as depth sensors (e.g., structured light sensors and/or depth sensors based on stereo imaging devices that can optically sense three-dimensional shapes), optical sensors such as self-mixing sensors and light detection and ranging (lidar) sensors that gather time-of-flight measurements and/or other measurements to determine distance between the sensor and an external object and/or that can determine relative velocity, monochromatic and/or color ambient light sensors that can measure ambient light levels, proximity sensors based on light (e.g., optical proximity sensors that include light sources such as infrared light-emitting diodes and/or lasers and corresponding light detectors such as infrared photodetectors that can detect when external objects are within a predetermined distance), optical sensors such as visual odometry sensors that gather position and/or orientation information using images gathered with digital image sensors in cameras, gaze tracking sensors, visible light and/or infrared cameras having digital image sensors configured to gather image data, optical sensors for measuring ultraviolet light, and/or other optical sensor components (e.g., light sensitive devices and, if desired, light sources), photodetectors coupled to light guides, associated light emitters, and/or other optical components (one or more light-emitting devices, one or more light-detecting devices, etc.). 
     Input-output devices  34  may also include audio components. The audio components may include one or more microphones to sense sound (e.g., an audio sensor in sensors  36  to sense audio signals) and may include sound-emitting components such as tone generators and one or more speakers. As shown in  FIG.  2   , for example, input-output devices  34  may include speaker  38 . Speakers may be used to support speaker-phone operations and/or may be used as ear speakers when device  10  is being held to a user&#39;s ear to make a telephone call, to listen to a voicemail message, or to listen to other audio output. 
     In addition to sensors  36 , display  14 , and speaker  38 , input-output devices  34  may include user input devices such as buttons and other devices  40 . Devices  40  may include, for example, optical components such as light-based output devices other than display  14  that are used to provide visual output to a user. The light-based output devices may include one or more light-emitting diodes, one or more lasers, lamps, electroluminescent devices, and/or other light emitting components. The light-based output devices may form status indicator lights. If desired, the light-based output devices may include illuminated icons (e.g., backlight symbols associated with power indicators, battery charge indicators, wireless signal strength indicators, notification icons, etc.). 
     Devices  40  may include electromagnets, permanent magnets, structures formed from magnetic material (e.g., iron bars or other ferromagnetic members that are attracted to magnets such as electromagnets and/or permanent magnets), batteries, etc. Devices  40  may also include power transmitting and/or receiving circuits configured to transmit and/or receive wired and/or wireless power signals and output components such as haptic output devices and other output components (e.g., electromagnetic actuators or other actuators that can vibrate to provide a user with a haptic alert and/or haptic feedback associated with operation of a touch sensor or other input devices). 
     A cross-sectional side view of device  10  of  FIG.  1    is shown in  FIG.  3   . As shown in  FIG.  3   , housing  12  may have one or more portions such as sidewall portions  12 W, front portion  12 F on front face F of device  10 , and rear portion  12 R on rear face R of device  10 . These portions may be formed from metal (e.g., aluminum, stainless steel, or other metals) or may be formed from polymer, glass, ceramic, and/or other materials. 
     Display  14  may be visible on front face F of device  10  and/or other portions of device  10 . For example, a viewer who is viewing device  10  in the −Z direction of  FIG.  3    (e.g., a user viewing device  10  from the front) may view the pixels of display  14  on front face F that face the user in the +Z direction). Display  14  may be overlapped by transparent portions of housing  12 , may have portions that are supported on the outermost surface of housing  12 , and/or may have portions that protrude from housing  12 . In some configurations, rigid protective transparent materials may form a display cover layer that protects display  14 . Display  14  may also be protected by attaching protective thin films to the outermost surface of display  14  and/or by incorporating protective thin films into display  14 . As an example, a clear polymer film may overlap the pixels of display  14  to help protect the circuitry of the pixels from damage and/or thin-film organic and/or inorganic layers may be incorporated into display  14  to help protect display  14 . In some arrangements, display  14  may include flexible protective material (e.g., a bendable polymer thin film, bendable inorganic thin-film layers, etc.). Transparent materials that may overlap display  14  (e.g., to protect display  14 ) may be formed from sapphire or other crystalline material, glass, polymer, transparent ceramic, inorganic dielectric materials such as transparent metal oxide thin films and/or other inorganic materials, and/or other transparent material and/or other flexible and/or rigid transparent materials. 
     The walls of housing  12  may separate interior region  44  of device  10  from exterior region  50  surrounding device  10 . Interior region  44  may include electrical components such as components  46 . Components  46  may include integrated circuits, discrete components, a battery, wireless circuit components such as a wireless power coil, and/or other components (see, e.g., control circuitry  30 , communications circuitry  32 , and input-output devices  34  of  FIG.  2   ). Components  46  may be interconnected using signal paths such as paths formed from traces on printed circuits (see, e.g., printed circuit  48 ). 
     To accommodate the sometimes competing desires for compact device size and large screen size, device  10  can be adjusted between a first state in which display  14  is unexpanded and a second state in which display  14  is expanded and therefore larger than when unexpanded. 
     With one illustrative arrangement, device  10  accommodates display bending. Display  14  may, for example, be folded inwardly so that left and right halves of display  14  face each other (e.g., when display  14  is formed on surface  62  of housing  12  of  FIG.  4   ). Display  14  may also be folded outwardly so that left and right halves of display  14  face away from each other (e.g., when display  14  is formed on surface  60  of housing  12  of  FIG.  4   ). If desired, device  10  may support both inward and outward folding. 
     Arrangements in which device  10  allows display  14  to be changed in size using sliding motions may also be used. As shown in  FIG.  5   , for example, device  10  may be adjusted so that structures in device  10  and display  14  slide (in direction  52  or other suitable direction) between a first (unexpanded) configuration in which only display area  14 ′ is visible and a second (expanded) configuration in which both display area  14 ′ and display area  14 ″ are visible. 
       FIG.  6    is a side view of device  10  in an illustrative configuration in which display  14  is sufficiently flexible to be scrolled. This allows display  14  to move in and out of housing  12 . In an unexpanded configuration, display  14  is rolled up and stored in housing  12  of  FIG.  6   . In an expanded configuration, display  14  is enlarged by unscrolling display  14  in direction  52  and causing display  14  to extend out of housing  12 . Other arrangements that allow display  14  to be changed in size and/or shape may also be used and/or combinations of these arrangements and/or the arrangements of  FIGS.  4 ,  5 , and  6    may be used. 
     If desired, display  14  may have an array of light-emitting pixels P. This type of arrangement is shown in  FIG.  7   . In the example of  FIG.  7   , display  14  includes display layer  14 L. Display layer  14 L may be flexible and may sometimes be referred to as a flexible display or flexible pixel array. As shown in  FIG.  7   , display layer  14 L may include substrate  71 A, a layer of pixels forming pixel array  71 B, and covering layer  71 C. 
     Substrate  71 A may be formed from a sheet of polyimide or other flexible polymer layer or may be formed from a layer of dielectric material (e.g., flexible glass or rigid glass in configurations in which substrate  71 A or portions of substrate  71 A include rigid substrate material). Substrate  71 A may be covered by thin-film layers forming pixels P and other thin-film circuitry. Pixels P may include thin-film transistors  78 , thin-film capacitors, thin-film light-emitting diodes  76  such as organic light-emitting diodes, and/or other thin-film circuitry. If desired, an array of pixels P for display  14  may be formed from micro-light-emitting diodes (sometimes referred to as microLEDs) formed from crystalline semiconductor dies. These dies may be mounted on a dielectric substrate such as a flexible dielectric substrate. One or more encapsulation layers such a layer  71 C may be used to protect and environmentally seal pixels P. Layer(s)  71 C may include organic and/or inorganic dielectric layers (e.g., thin-film layers). 
     Display  14  may include additional layers such as one or more support layers on the rear of display layer  14 L (see, e.g., backing layer  70 ) and/or one or more outwardly facing layers on the outwardly facing side of display layer  14 L (see, e.g., layer  72 ). These layers may be attached above and below display layer  14 L using layers of adhesive, using other coupling structures, by forming thin-film layers directly on display  14 , and/or by incorporating other layers overlapped by pixels P into display  14 . Backing layers such a layer  70  may be formed from metal (e.g., thin flexible metal that can withstand repeated bending and unbending), may be formed from polymer, may be formed from other materials, and/or may be formed from combinations of these materials. During bending, layers such as layer  70  may help protect display  14  from wrinkling or other potentially damaging deformation. Additional layer(s)  72  may include polarizer layers, wave plates, filters, protective cover layers, privacy films, and/or other display layers. 
       FIG.  8    is a cross-sectional side view of an illustrative electronic device with a display that is expandable using a folding motion. In the example of  FIG.  8   , display  14  is located on the outer surface of housing  12  as device  10 , housing  12 , and display  14  bends about bend axis  58 . If desired, device  10 , housing  12 , and display  14  may support inward bending. The location of bend axis  58  need not be fixed and may change dynamically as device  10  folds. For example, when bending motion starts with very large curvature (e.g., a large bending radius), bend axis  58  may be far away from device  10 , whereas when the bending motion is being completed, bend axis  58  may be close to device  10 . 
     Display  14  may be a unitary flexible display (e.g., a flexible organic light-emitting diode panel or microLED display with a flexible substrate) or display  14  may have rigid and flexible portions such as central flexible portion  14 F and outer rigid portions  14 R of display  14  of  FIG.  8   . Flexible substrates for display  14  may, if desired be stretchable. A flexible portion of display  14  (e.g., portion  14 F) overlaps bend axis  58  (which extends into the page in the example of  FIG.  8   ), thereby allowing display  14  to bend about bend axis  58  as housing portions  12 - 1  and  12 - 2  are moved towards each other in directions  80 . 
     A cross-sectional side view of an illustrative display such as a flexible display is shown in  FIG.  9   . As shown in  FIG.  9   , display  14  may have multiple layers that are stacked on top of each other. The layers of display  14  may be attached to each other using coupling structures such as adhesive layers  84  (as an example). Adhesive layers  84  may be formed from solid sheets of adhesive (e.g., polymer adhesive) and/or may be formed from adhesive patterned to form a grid, islands (e.g., columns of adhesive), strips of adhesive, etc. 
     Supportive backing layer  70  may be used to provide support to the layers of display  14 . Layer  70  may be formed from polymer, metal (e.g., flexible metal such as spring metal), and/or other materials. For example, layer  82  may be a metal backing film that helps prevent wrinkling or other undesired deformation in display  14  as display  14  is bent. Layer  70  may be attached to the inner surface of display layer  14 L by one of adhesive layers  84 . Additional layers  72  may be coupled to the outer surface of display layer  14 L by another of adhesive layers  84 . Additional layers  72  may include, for example, a polarizer such as circular polarizer  88  to suppress ambient light reflections from display layer  14 L and protective layer  90 . One of adhesive layers  84  may be used to couple layers  90  and  88 . 
     Layer  90  may be formed from a single layer of glass (e.g., a glass layer having a thickness of 30-100 microns, at least 10 microns, at least 20 microns, at least 40 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 300 microns, less than 250 microns, less than 150 microns, less than 75 microns, less than 40 microns, less than 15 microns, or other sufficiently low value to allow layer  90  to flex), a flexible layer of polymer, a transparent layer formed from other materials, and/or a composite layer formed from multiple layers of material. In the example of  FIG.  10   , layer  90  is formed from an upper layer of polymer such as upper layer  94  and a lower layer of glass such as layer  92 . Adhesive layer  84  may be used to couple layers  92  and  94  together. As shown in the illustrative top view of patterned adhesive layer  84  of  FIG.  11   , adhesive layer  84  can be patterned so that adhesive  84  only appears in isolated islands (columns) surrounded by gaps  96  that are filled with gaseous or liquid fluid  96  (e.g., pillars of adhesive may be separated by air gaps or gaps filled with other gas or liquid). The islands of adhesive in a patterned adhesive layer  84  may have lateral dimensions of 10-100 microns, more than 20 microns, less than 500 microns, or other suitable size. Solid and/or patterned adhesive layers  84  may be soft to allow the layers of display  14  to shift (exhibit shearing motion) with respect to each other during display bending, thereby reducing stress. As an example, the adhesive material used in forming adhesive layer  84  may have a modulus of 10 kPa or lower. 
     To help reduce stress buildup and damage to display  14  during bending, one or more of the layers of display  14  may be attached using structures that couple the layers to each other in the vertical (Z) dimension (layer-to-layer coupling) while allowing shearing movement along a dimension that is perpendicular to bend axis  58  (e.g., along the Y dimension). Illustrative structures that allow shear movements while coupling adjacent layers in display  14  to each other are shown in  FIGS.  12  and  13   . In the example of  FIG.  12   , the display includes upper layer  104  and lower layer  106 . Layers  104  and  106  may, in general, include any layers of the type shown in  FIG.  9    and/or other covering and/or supportive display layers. As an example, layer  104  may include an organic light-emitting diode panel and layer  106  may include one or more supporting layers. As shown in  FIG.  12   , layer  104  may be coupled to layer  100  and layer  106  may be coupled to layer  102 . Layers  100  and  102  form a shearing attachment layer (layer  98 ) that permits movement along the Y dimension as display  14  is bent about a bend axis that runs parallel to the X dimension. Protruding portion  100 ′ of layer  100  may have a shape that engages with surrounding portions  102 ′ of layer  102  and thereby helps hold layer  100  to layer  102  in the Z dimension. Layers  100  and  102  may be formed from flexible polymers and may have coatings of lubricant and/or may be formed from slippery materials (e.g., polytetrafluoroethylene) to prevent layers  100  and  102  from binding. Other interlocking shapes may be used for the structures of layer  98 , if desired (e.g., layer  106  may have protruding portions in addition to or instead of providing protrusions  100 ′ in layer  100 ).  FIG.  13    shows how downward protrusions such as structures  100 ″ may interlock with upward protrusions such as structures  102 ″. Remaining portions of layer  98  may be filled with fluid (liquid or gas) and/or lubricant (e.g., oil, lubricating particles, etc.). If desired, conductive material (e.g., metal layers, etc.) may be used in forming one or more of the layers of  FIGS.  12  and  13   . This allows an electrostatic force clutch mechanism to be implemented. When no electric field is applied to opposing conductive layers, there is no electrostatic force and the layers are free to slip relative to each other, thereby allowing device  10  to bend. When a non-zero control voltage is applied to opposing conductive layers, an electric field develops that holds the otherwise slippery layers in place. By preventing the layers from sliding past each other using applied electrostatic force, the clutch mechanism can effectively lock device  10  and prevent bending. 
     To prevent undue stress in display  14  when a device is folded, device  10  may be provided with hinge structures that prevent kinks and other undesired features from developing in display  14  as portions of device  10  rotate about bend axis  58 . This issue is illustrated in  FIGS.  14  and  15   . As shown by illustrative folding device  10 BD of  FIG.  14   , device housing portions  12 BD may fold about hinge axis  58 BD to allow display  14 BD to fold back on itself on the outer surfaces of device housing portions  12 BD. But when this type of device is unfolded, there is a risk that display  14 BD may be deformed in region  110  overlapping hinge axis  58 BD. 
     To avoid this issue, folding device  10  can be provided with hinge structures that do not impart undue display stress during folding and unfolding operations. Consider, as an example, the illustrative device configuration of  FIG.  16   . As shown in  FIG.  16   , device  10  may have a first housing portion  12 L and a second housing portion  12 R. Portions  12 L and  12 R may form first and second housing structures (e.g., a left housing member and a corresponding right housing member, upper and lower housing halves, etc.) and may, if desired, have hollow interiors that enclose batteries, control circuitry, input-output devices, and other device components. Hinge structures  12 H may include multiple hinge links  112  and may be used in coupling portions  12 L and  12 R together. Display  14  may be supported on the outer or inner surface of housing portions  12 L and  12 R and may overlap bend axis  58 .  FIG.  17    shows how hinge structures  12 H may support flexible display  14  and help prevent kinks and other undesired wrinkling features from developing in display  14  as device  10  is folded about bend axis  58 . 
     To help reduce stress during folding and unfolding, hinge structures  12 H may be configured to ensure that stress is minimized within the thin-film structures of display  14 . As shown in  FIG.  18   , for example, device  10  may be configured so that display  14  has a reduced stress plane  114  (e.g., a neutral stress plane or approximately neutral stress plane) that lies within the interior of display  14  (e.g., in alignment with pixel array  71 B in display layer  14 L of  FIG.  7    or in line with other brittle display layers such as an encapsulation layer in display layer  14 L or a display cover layer for display  14 ). When display  14  of  FIG.  18    is bent about bend axis  58  as shown in  FIG.  19   , upper portion  14 TP of display  14  may experience tensile stress as shown by arrows  116  and lower portion  14 BP of display  14  may experience compressive stress as shown by arrows  118 . Due to the positioning of reduced stress plane  114  within pixel array  71 B, however, layer  14 L and pixel array  71 B will experience relatively small amounts of stress during bending. 
     An illustrative hinge structure that may be used in device  10  to help position reduced stress plane  114  within display  14  (e.g., within display layer  14 L and pixel array  71 B) is shown in  FIG.  20   . In the example of  FIG.  20   , hinge structure  12 H is a virtual pivot roller hinge having hinge members that rotate with respect to each other as device  10  is folder. 
     As shown in  FIG.  20   , hinge structure  12 H may have a series of links  120  coupled by respective bars  122 . Bars  122  may have portions that extend below the links and thereby hold the bars in place. For example, bar BA has an upper portion above links LA and a lower portion below link LA. Post portion  126  of bar BA couples the upper and lower portions of bar BA together. Post portion  126  moves within an opening within link LA. When display  14  is planar (e.g., when device  10  is in its expanded unfolded state, post portion  126  does not contact the sides of the opening. When display  14  and device  10  are bent about bend axis  58 , the left side of post portion  126  may contact a stop surface such as stop surface  124 , thereby preventing further bending of  124 L and the right side of post portion  126  may contact right stop surface  124 R. Stop surface  128  of link LA and stop surface  130  of the lower part of bar BA may also contact each other. When the stop surfaces contact each other in this way, additional bending will be stopped (e.g., to prevent excessive forward bending and to prevent back bending of hinge structures  12 H). 
     The curved lower surfaces of the upper portions of bars  122  such as lower bar bearing surface  132  have profiles (circular arc profiles) that form parts of a circles and bear against opposing upwardly facing curved surfaces of links  120  (see, e.g., opposing circularly curved upper link bearing surface  134 ). Lower bar bearing surface  136  also has a circularly curved shape and bears against opposing curved lower bearing surface  138  of link A. The circular arcs formed from the cross-sectional profiles of these bearing surfaces allow links  120  and bars  122  to rotate with respect to each other about pivot points such as illustrative pivot point  140  for link LA and associated bar BA. In particular, the curved shapes of the bearing surfaces allow link LA to rotate about a rotational axis aligned with pivot point  140  when link LA is moved in direction  150  relative to bar BA. During rotation, link LA is not blocked by link LB, which lies out of the page in  FIG.  20    (e.g., out of plane with respect to link LA). 
     Pivot points such as pivot point  140  may sometimes be referred to a virtual pivot points, because they do not lie within the bodies of bars  122  (as would be the case if links  120  formed chain links and bars  122  were formed from solid rods forming axles for the chain links). This allows pivot points such as pivot point  140  and associated reduced stress plane  114  to be located within display  14  (e.g., within layer  14 L and aligned with pixels  71 B or other brittle or otherwise stress-sensitive display layers as described in connection with  FIGS.  18  and  19   ). By locating pivot points  140  and reduced stress plane  114  in alignment with pixels  71 B or other brittle display layers in display  14 , stress on pixels  71 B or other brittle display layers can be reduced. 
     As shown in  FIG.  20   , display  14  may rest on upper surfaces  142  of links  120  and upper surfaces of bars  122 . Surfaces  144  (and, if desired, surfaces  142 ) may have curved (e.g., slightly convex) cross-sectional profiles so that display  14  is smoothly and evenly supported when display  14  is in its bent configuration. 
       FIGS.  21 ,  22 , and  23    are perspective views of hinges structure  12 H in unbent, partially bent, and fully bent configurations, respectively. Display  14  is not shown in  FIGS.  21 ,  22 , and  23    to permit hinge structures  12 H to be viewed. As shown in  FIG.  21   , bars  122  have elongated shapes that run parallel to bend axis  58 . In the example of  FIG.  21   , hinge structures  12 H have four bars  122 . Hinge structures with fewer bars  122  or more bars  122  may be used, if desired. As shown in  FIG.  21   , portions CP of the hinge structures  12 H that couple adjacent hinge structures (e.g., linking structures) may be staggered with respect to each other. There may be, for example, two link portions CP that couple the first and second bars in  FIG.  21   , three offset link portions CP that couple the second and third bars in  FIG.  21   , etc. 
     A cross-sectional side view of device  10  showing how housing portions  12 - 1  and  12 - 2  may be joined using bendable hinge structures  12 H is shown in  FIG.  24   . To prevent undesired stress on display  14 , it may be desirable to synchronize the movement of one half of housing  12  with the other. For example, it may be desirable to configure hinge structure  12 H so that movement of first housing portion  12 - 1  through an angle A will cause second housing portion  12 - 2  to move through an equal angle A, as shown in  FIG.  24   . 
     One way in which to synchronize movement of housings  12 - 1  and  12 - 2  is to provide meshing gears in the components of hinge structures  12 H. In the example of  FIG.  25   , hinge structures  12 H include chain link members  152  with gear teeth at opposing ends. Each member  152  has an associated pair of pins  154  that help hold together two other chain link members. With this arrangement, movement of the chain link member on one end of chain hinge structures  12 H will cause synchronized movement of a chain link member at an opposing end of chain hinge structures  12 H. 
     Consider, as an example, a scenario in which the location of member LM 2  is held fixed and in which tip TP of member LM 4  is moved in direction  156 . Gear teeth TH 1  of member LM 4  engage gear teeth TH 2  of member LM 2 , so movement of member LM 4  in direction  156  causes angle AN between LM 2  and LM 4  to decrease. This moves the position of pin PP 1  in direction  158  to the position shown by pin PP 2 . As a result of this movement, member LM 3  rotates in direction  160 . Teeth TH 3  of member LM 3  engage teeth TH 4  of member LM 1 , so rotation of member LM 3  in direction  160  causes member LM 1  to rotate in direction  162 . As this example demonstrates, counterclockwise rotation of member LM 4  in direction  156  produces a corresponding synchronized clockwise rotation of member LM 1 . Synchronization of the behavior of links  152  in this way helps constrain the relative motion of each link to the next and ensures that display  14  is bent smoothly and evenly during folding. If desired, geared engagement structures of the type shown in  FIG.  25    may be used with hinge links such as links  120  of  FIG.  20   . 
     It may also be desirable to synchronize motion of hinge structures such as bars  122  of  FIG.  20   . With one illustrative arrangement, belt structures such as belts B 1  and B 2  of  FIG.  26    may be used to synchronize rotation of bars such as bars BA and BB. Rollers (pulleys, etc.) such as roller R 1  may be used to route belts B 1  and B 2  to opposing edges of bars BA and BB. With this arrangement, for example, rotation of bar BA in direction  166  will cause edge  168  of bar BA to move upward in direction  170 , thereby pulling belt B 1  up. Roller R 1  causes portion  172  of belt B 1  to pull downwards in direction  174  on edge  176  of bar BB, thereby causing bar BB to rotate in direction  178 . Belt B 2  may similarly be used to synchronize rotation of bars BA and BB when bar BA is rotated in direction  180 . 
     In some configurations, friction may be produced between portions of hinge structures  12 H (e.g., to control the amount of force used to open and close hinge structures  12 H). As shown in  FIG.  27   , for example, bar B′ may have a cavity such as cavity  182 . Biasing member  184  (e.g., compressible foam, a spring, etc.) may push friction member  186  upwards against lower surface  188  of link L′, thereby imparting friction between link L′ and bar B′ (e.g., member  184 ) as hinge structures  12 H are folded.  FIG.  28    shows how detent structures may be formed between moving members (e.g., bars and links) in hinge structures  12 H. In the example of  FIG.  28   , member  190  (e.g., a link) has protrusions  192  that engage with recesses  194  in member  196  (e.g., a bar). When sufficient rotational force is applied, protrusions  192  will disengage from recesses  194  (overcoming biasing pressure  198  from hinge structure  200 ) and thereby allow member  190  to rotate relative to member  196 . 
     If desired, movement of housing structures  12 - 1  and  12 - 2  and the curvature of device  10  in the bending portion of display  14  can be controlled using a sheet of spring metal or other flexible sheet of material. Consider, as an example, device  10  of  FIG.  29   . As shown in  FIG.  29   , device  10  may include first housing portion  12 - 1  and second housing portion  12 - 2 . Hinge structures  12 H may be used to couple portions  12 - 1  and  12 - 2  for folding motion about bend axis  58  (e.g., so that device  10  can be placed in shapes such as the shapes of  FIGS.  30 ,  31 , and  32   ). Flexible sheet  202  (e.g., a sheet of spring metal or other flexible material such as flexible polymer, flexible sheets for from other materials and/or stacks of laminated sheets of one or more materials, etc.) may overlap hinge structure  12 H and, if desired, may overlap some or all of housing portions  12 - 1  and  12 - 2 . When device  10  is bent about bend axis  58 , flexible sheet  202  will bend about axis  58  while resisting sharp kinks or other features that might wrinkle display  14 . Sheet  202  may serve as backing layer  70  of display  14  ( FIG.  7   ) or may be serve as an additional supporting layer for display  14 . 
     To facilitate folding and unfolding (e.g., to prevent excess stress in a folded or unfolded state), some or all of sheet  202  may be prestressed. For example, sheet  202  or portions of sheet  202  may be prestressed to help overcome the spring force of a flexible display that is trying to open device  10  (e.g., to make closing the device easier). If desired, sheet  202  may be used to help enforce a constant curvature in display  14  as display  14  is bent. The incorporation of sheet  202  may also help synchronize the movement of links in hinge  12 H.  FIG.  33    shows how openings  202 H may be formed at one or more locations in sheet  202  (e.g., locations overlapping bend axis  58 ). By including openings  202 H, the flexibility of sheet  202  may be enhanced. 
     In some configurations, device  10  may have a movable hinge pin support member such as a sliding hinge pin support plate. A side view of an illustrative hinge pin support plate is shown in  FIG.  34   . As shown in  FIG.  34   , hinge pin support plate  204  may have a planar portion  204 F and a protruding portion  204 P. Hinge pin  206  may be supported in a hole in protrusion  204 P. 
       FIG.  35    is a side view of an illustrative folding device that includes sliding hinge pin support plate  204 . As shown in  FIG.  35   , hinge pin support plate  204  may be coupled to housing portion  12 - 1  and may slide relative to housing  12  as device  10  is folded and unfolded. In particular, housing portion  12 - 1  may move in direction  208  when device  10  is folded in direction  210 . This causes hinge pin support plate  204  to move in direction  208  to position  204 ′. As a result, hinge pin  206  moves to position  206 ′. The dynamic movement of the location of hinge pin  206  during folding helps ensure that the structures of housing portion  12 - 1  can smoothly wrap around curved surface  212  of portion  12 - 1 , thereby helping to smoothly bend display  14 . 
     A perspective view of illustrative device  10  of  FIG.  35    is shown in  FIG.  36   . In the arrangement of  FIG.  36   , device  10  is in a partly folded state. As shown in  FIG.  36   , the outer surfaces of housing portions  12 - 1  and  12 - 2  may be covered with flexible display  14  (and, if desired, may include flexible supporting structures such as flexible sheet  202  of  FIG.  29   ). 
     Housing portion  12 - 2  is configured to receive the opposing ends of hinge pin  206 , so that housing portion  12 - 1  rotates relative to housing portion  12 - 2  about hinge axis  58 . During folding of device  10 , portion  12 - 1  moves in direction  210 , which causes hinge pin support plate  204  to move in direction  208  within a track formed by parts of portion  12 - 1  that overlap a protruding lip portion of plate  208  such as lip  204 L. Links  212  are joined to adjacent links  212  in the hinge structures of device  10  using link joints  214 , so that links  212  form bendable hinge structures. Links  212  have protruding portions such as protrusions  212 P that overlap lip  204 L, thereby preventing plate  204  and links  212  from separating. The surfaces of links  212  that face display  14  may be attached to display  14  (and/or may be attached to associated supporting structures such as flexible sheet  202 ).  FIG.  37    shows how links  212  are smoothly wrapped around surface  218  of housing portion  12 - 2 , which surrounds (is at least partly wrapped around) hinge pin  206 , during folding of housing portions  12 - 1  and  12 - 2  together due to the sliding movement of plate  204  and hinge pin  206 . The configuration of  FIG.  36    may be used to align bend axis  58  with display  14 , thereby helping to place a reduced stress plane (e.g., a neutral stress plane or an approximately neutral stress plane) within display  14  (e.g., within a stress-sensitive portion of display  14  such as a layer of thin-film pixel structures, an encapsulation layer formed from brittle dielectric materials, a glass layer or other stress-sensitive layer serving as a display cover layer, etc.). 
     Device  10  may be operated in a system that uses personally identifiable information. It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     The foregoing is 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: 20200207
Publication Date: 20250128
Grant Date: 20250128
Priority Date: 20190528
Inventors: HALE, OWEN D.
SANO, TATSUYA
HUANG, CHANG-CHIA
AFSAR, YASMIN F.
KIM, HOON SIK
WITTENBERG, MICHAEL B.
Assignee: APPLE INC
CPC Classifications: [{"code": "E05Y2999/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05D3/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D3/122", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/0017", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05Y2999/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1641", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05Y2800/244", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05Y2800/22", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05D11/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05D3/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05D3/122", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05D3/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K5/0226", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1681", "inventive": true, "first": true, "tree": "[]"}, {"code": "E05Y2999/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K5/0017", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D3/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D3/122", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/0226", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 73549547