PATENT DOCUMENT

Publication Number: US-11961946-B2
Application Number: US-202117390504-A
Country: US
Kind Code: B2

Title: Electronic devices with flexible displays

Abstract:
A foldable electronic device may have a foldable housing. The foldable housing may be configured to bend about a bend axis. First and second portions of the housing that rotate relative to each other may be coupled by a hinge that is aligned with the bend axis. A foldable display may be coupled to the foldable housing and may be configured to bend along the bend axis as the foldable housing is folded. The display may have an array of pixels supported by a metal layer. The pixels may be interposed between a display cover layer and the metal layer. The foldable housing may have a support layer. To help support the display for bending about the bend axis while preventing damage to the display when the display is contacted by an external object, a spring layer may be interposed between the metal layer and the support layer.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a foldable housing that is configured to bend about a bend axis and that has a support layer; 
 a flexible display panel separated from the support layer by a gap; and 
 a spring layer between the support layer and the flexible display panel, wherein the spring layer comprises a spring having a first end attached to the support layer and a second end attached to the flexible display panel and extending across the gap. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the spring layer comprises an array of springs containing the spring. 
     
     
       3. The electronic device defined in  claim 2  wherein the array of springs comprises springs selected from the group consisting of: spiral springs, dome springs, corrugated springs, springs formed from axially compressible cylindrical tubes with flexibility-enhancement sidewall openings, springs with arms, and cantilever springs. 
     
     
       4. The electronic device defined in  claim 3  wherein the array of springs comprises metal springs. 
     
     
       5. The electronic device defined in  claim 4  further comprising foam posts between the support layer and the flexible display panel. 
     
     
       6. The electronic device defined in  claim 5  further comprising a force sensor configured to measure force applied to the flexible display panel. 
     
     
       7. The electronic device defined in  claim 1  wherein the flexible display panel has a metal layer and wherein the spring is welded to the metal layer. 
     
     
       8. The electronic device defined in  claim 1  wherein the flexible display panel has a metal layer and wherein the spring is attached to the metal layer with adhesive. 
     
     
       9. The electronic device defined in  claim 1  wherein the spring layer comprises an additional spring of a first thickness that is different than a second thickness of the spring. 
     
     
       10. The electronic device defined in  claim 1  wherein the flexible display panel comprises an array of light-emitting diodes, the electronic device further comprising a display cover layer that overlaps the array of light-emitting diodes. 
     
     
       11. The electronic device defined in  claim 1  wherein the support layer comprises a metal midplate. 
     
     
       12. The electronic device defined in  claim 1  further comprising a force sensor, wherein the spring comprises a metal spring and wherein the force sensor is on the metal spring. 
     
     
       13. The electronic device defined in  claim 12  wherein the metal spring has at least one arm and wherein the force sensor comprises a strain gauge on the arm. 
     
     
       14. The electronic device defined in  claim 1  wherein the foldable housing has a hinge aligned with the bend axis, wherein the spring layer comprises an array of springs containing the spring, and wherein the array of springs is characterized by a spring-center-to-spring-center pitch of less than 3 mm and a thickness of 0.2 to 3 mm. 
     
     
       15. A foldable portable electronic device comprising:
 a housing having first and second portions coupled for rotational motion at a bend axis, wherein the first portion of the housing is configured to fold over the second portion of the housing; 
 a display cover layer; 
 an array of pixels configured to display an image through the display cover layer; 
 a metal layer coupled to the array of pixels; and 
 a spring layer having an array of metal springs between the first portion of the housing and the metal layer and between the second portion of the housing and the metal layer. 
 
     
     
       16. The foldable portable electronic device defined in  claim 15  wherein a strip-shaped area of the spring layer that overlaps the bend axis has first springs of a first stiffness and wherein other areas of the spring layer have second springs with a second stiffness that is different than the first stiffness. 
     
     
       17. A foldable electronic device, comprising:
 a foldable housing having a first metal layer; 
 a foldable display having pixels supported by a second metal layer; 
 an array of metal springs interposed between the first and second metal layers; and 
 a sheet of metal that contains the array of metal springs. 
 
     
     
       18. The foldable electronic device defined in  claim 17  wherein foldable housing has a hinge, wherein the foldable housing is configured to bend about a bend axis that is aligned with the hinge, wherein the array of metal springs overlaps the bend axis, and wherein the array of metal springs is welded to the second metal layer. 
     
     
       19. The foldable electronic device defined in  claim 17  wherein the array of metal springs has bases attached to the sheet of metal. 
     
     
       20. The foldable electronic device defined in  claim 19  wherein the array of metal springs has tips that extend upwards from the sheet of metal. 
     
     
       21. The foldable portable electronic device defined in  claim 15 , wherein the array of pixels is within a flexible display panel and wherein the metal layer is separate from and is attached to the flexible display panel. 
     
     
       22. The foldable portable electronic device defined in  claim 15 , wherein the array of pixels is within a flexible display panel and wherein the metal layer is a layer of the flexible display panel.

Description:
This application claims the benefit of U.S. provisional patent application No. 63/076,835, filed Sep. 10, 2020, 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 have displays. Portability is often a concern for electronic devices, which tends to limit available real estate for displays. 
     SUMMARY 
     A foldable electronic device may have a foldable housing. The foldable housing may be configured to bend about a bend axis. First and second portions of the housing that rotate relative to each other may be coupled by a hinge that is aligned with the bend axis. A foldable display may be coupled to the foldable housing and may be configured to bend along the bend axis as the foldable housing is folded. The device may be placed in a closed configuration in which the display is folded for storage and an open configuration in which the display is unfolded and available for displaying images for a user. 
     The foldable display may have an array of pixels supported by a metal layer. The pixels may be interposed between a display cover layer and the metal layer. The foldable housing may have a rear housing wall or other support layer. To help support the display for bending about the bend axis while preventing damage to the display when the display is contacted by an external object, a spring layer may be interposed between the metal layer and the support layer. 
     The spring layer may be formed from an array of springs. The springs may be formed from metal. Different springs may be formed in different areas. For example, a strip-shaped area aligned with the bend axis may have softer springs than other areas. 
     Sensors may be included in the spring layer. The sensors may be formed from force sensing structures such as strain gauges and may be supported on portions the springs or may be located adjacent to the springs. If desired, foam posts and other compressible structures may be interspersed with the springs to help adjust the performance of the spring layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an illustrative electronic device in accordance with an embodiment. 
         FIG.  2    is a perspective view of an illustrative electronic device with a display 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 a cross-sectional side view of an illustrative display supported by springs in accordance with an embodiment. 
         FIG.  5    is a graph in which compression modulus has been plotted as a function of compression ratio for different types of flexible display support systems in accordance with an embodiment. 
         FIGS.  6  and  7    are cross-sectional side views of illustrative electronic device display system mounting arrangements in accordance with embodiments. 
         FIGS.  8 ,  9 ,  10 , and  11    are side views of different illustrative spring-based systems for supporting flexible displays in accordance with embodiments. 
         FIG.  12    is a cross-sectional side view of a display in accordance with an embodiment. 
         FIGS.  13 ,  14 ,  15 ,  16 ,  17 ,  18 ,  19 ,  20 ,  21 , and  22    are views of illustrative springs in accordance with embodiments. 
         FIG.  23    is a cross-sectional side view of a spring coupled to a metal layer in accordance with an embodiment. 
         FIG.  24    is a top view of an array of illustrative springs formed from a sheet of metal in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with displays. Displays may be used for displaying images for users. Displays may be formed from arrays of light-emitting diode pixels or other pixels. For example, a device may have an organic light-emitting diode display or a display formed from an array of micro-light-emitting diodes (e.g., diodes formed from crystalline semiconductor dies). 
     A schematic diagram of an illustrative electronic device having a display is shown in  FIG.  1   . Device  10  may be a cellular telephone, tablet computer, laptop computer, wristwatch device or other wearable device, a television, a stand-alone computer display or other monitor, a computer display with an embedded computer (e.g., a desktop computer), a system embedded in a vehicle, kiosk, or other embedded electronic device, a media player, or other electronic equipment. Configurations in which device  10  is a wristwatch, cellular telephone, or other portable electronic device may sometimes be described herein as an example. This is illustrative. Device  10  may, in general, be any suitable electronic device with a display. 
     Device  10  may include control circuitry  20 . Control circuitry  20  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  20  may be used to 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. During operation, control circuitry  20  may use a display and other output devices in providing a user with visual output and other output. 
     To support communications between device  10  and external equipment, control circuitry  20  may communicate using communications circuitry  22 . Circuitry  22  may include antennas, radio-frequency transceiver circuitry (wireless transceiver circuitry), and other wireless communications circuitry and/or wired communications circuitry. Circuitry  22 , which may sometimes be referred to as control circuitry and/or control and communications circuitry, may support bidirectional wireless communications between device  10  and external equipment over a wireless link (e.g., circuitry  22  may include radio-frequency transceiver circuitry such as wireless local area network transceiver circuitry configured to support communications over a wireless local area network link, near-field communications transceiver circuitry configured to support communications over a near-field communications link, cellular telephone transceiver circuitry configured to support communications over a cellular telephone link, or transceiver circuitry configured to support communications over any other suitable wired or wireless communications link). Wireless communications may, for example, be supported over a Bluetooth® link, a WiFi® link, a wireless link operating at a frequency between 6 GHz and 300 GHz, a 60 GHz link, or other millimeter wave link, cellular telephone link, wireless local area network link, personal area network communications link, or other wireless communications link. Device  10  may, if desired, include power circuits for transmitting and/or receiving wired and/or wireless power and may include batteries or other energy storage devices. For example, device  10  may include a coil and rectifier to receive wireless power that is provided to circuitry in device  10 . 
     Device  10  may include input-output devices such as devices  24 . Input-output devices  24  may be used in gathering user input, in gathering information on the environment surrounding the user, and/or in providing a user with output. Devices  24  may include one or more displays such as display  14 . Display  14  may be an organic light-emitting diode display, a liquid crystal display, an electrophoretic display, an electrowetting display, a plasma display, a microelectromechanical systems display, a display having a pixel array formed from crystalline semiconductor light-emitting diode dies (sometimes referred to as microLEDs), and/or other display. Configurations in which display  14  is an organic light-emitting diode display or microLED display are sometimes described herein as an example. 
     Display  14  may have an array of pixels configured to display images for a user. The pixels may be formed as part of a display panel that is bendable. This allows device  10  to be folded and unfolded about a bend axis. For example, a flexible (bendable) display in device  10  may be folded so that device  10  may be placed in a compact shape for storage and may be unfolded when it is desired to view images on the display. 
     Sensors  16  in input-output devices  24  may include force sensors (e.g., strain gauges, capacitive force sensors, resistive force sensors, etc.), audio sensors such as microphones, touch and/or proximity sensors such as capacitive sensors (e.g., a two-dimensional capacitive touch sensor integrated into display  14 , a two-dimensional capacitive touch sensor overlapping display  14 , and/or a touch sensor that forms a button, trackpad, or other input device not associated with a display), and other sensors. If desired, sensors  16  may include optical sensors such as optical sensors that emit and detect light, ultrasonic sensors, optical touch sensors, optical proximity sensors, and/or other touch sensors and/or proximity sensors, monochromatic and color ambient light sensors, image sensors, fingerprint sensors, temperature sensors, sensors for measuring three-dimensional non-contact gestures (“air gestures”), pressure 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), health sensors, radio-frequency sensors, depth sensors (e.g., structured light sensors and/or depth sensors based on stereo imaging devices that capture three-dimensional images), optical sensors such as self-mixing sensors and light detection and ranging (lidar) sensors that gather time-of-flight measurements, humidity sensors, moisture sensors, gaze tracking sensors, and/or other sensors. In some arrangements, device  10  may use sensors  16  and/or other input-output devices to gather user input. For example, buttons may be used to gather button press input, touch sensors overlapping displays can be used for gathering user touch screen input, touch pads may be used in gathering touch input, microphones may be used for gathering audio input, accelerometers may be used in monitoring when a finger contacts an input surface and may therefore be used to gather finger press input, etc. 
     If desired, electronic device  10  may include additional components (see, e.g., other devices  18  in input-output devices  24 ). The additional components may include haptic output devices, audio output devices such as speakers, light-emitting diodes for status indicators, light sources such as light-emitting diodes that illuminate portions of a housing and/or display structure, other optical output devices, and/or other circuitry for gathering input and/or providing output. Device  10  may also include a battery or other energy storage device, connector ports for supporting wired communication with ancillary equipment and for receiving wired power, and other circuitry. 
       FIG.  2    is a perspective view of electronic device  10  in an illustrative configuration in which device  10  is a portable electronic device such as a cellular telephone or tablet computer. As shown in  FIG.  2   , device  10  may have a display such as display  14 . Display  14  may cover some or all of the front face of device  10 . Touch sensor circuitry such as two-dimensional capacitive touch sensor circuitry may be incorporated into display  14 . 
     Display  14  may be mounted in housing  12 . Housing  12  may form front and rear housing walls, sidewall structures, and/or internal supporting structures (e.g., a frame, midplate member, etc.) for device  10 . Glass structures, transparent polymer structures, and/or other transparent structures that cover display  14  and other portions of device  10  may provide structural support for device  10  and may sometimes be referred to as housing structures or display cover layer structures. For example, a transparent housing portion such as a glass or polymer housing structure that covers and protects a pixel array in display  14  may serve as a display cover layer for the pixel array while also serving as a housing wall on the front face of device  10 . The portions of housing  12  on the sidewalls and rear wall of device  10  may be formed from transparent structures and/or opaque structures. 
     Housing  12  may have flexible structures (e.g., bendable housing walls structures) and/or hinge structures such as hinge  30 . Hinge  30  may have a hinge axis aligned with device bend axis  28 . Hinge  30  and/or flexible housing structures that overlap bend axis  28  may allow housing  12  to bend about bend axis  28 . For example, housing  12  may have a first portion on one side of bend axis  28  and a second portion on an opposing side of bend axis  28  and these two housing portions may be coupled by hinge  30  for rotational motion about axis  28 . 
     As housing  12  is bent about bend axis  28 , the flexibility of display  14  allows display  14  to bend about axis  28 . In an illustrative configuration, housing  12  and display  14  may bend by 180°. This allows display  14  to be folded back on itself (with first and second outwardly-facing portions of display  14  facing each other). The ability to place device  10  in a folded configuration in this way may help make device  10  compact so that device  10  can be stored efficiently. When it is desired to view images on display  14 , device  10  may be unfolded about axis  28  to place device  10  in the unfolded configuration of  FIG.  2   . This allows display  14  to lie flat and allows a user to view flat images on display  14 . The ability to fold display  14  onto itself allows device  10  to exhibit an inwardly folding behavior. Display  14  may be sufficiently flexible to allow device  10  to be folded outwardly and/or inwardly. 
     Device  10  of  FIG.  2    has a rectangular outline (rectangular periphery) with four corners. As shown in  FIG.  2   , a first pair of parallel edges (e.g., the left and right edges of device  10  in the example of  FIG.  2   ) may be longer than a second pair of parallel edges (e.g., the upper and lower edges of device  10  of  FIG.  2   ) that are oriented at right angles to the first pair of parallel edges. In this type of configuration, housing  12  is elongated along a longitudinal axis. Housing  12  may have other shapes, if desired. With an arrangement of the type shown in  FIG.  2   , the length of device  10  along its longitudinal axis may be reduced by folding device  10  about axis  28 . 
       FIG.  3    is a cross-sectional side view of an illustrative foldable electronic device. Device  10  of  FIG.  3    may bend about bend axis  28 . Display  14  includes an array of pixels P forming display panel  14 P under an inwardly facing surface of display cover layer  14 CG. Display panel  14 P may be, for example, a flexible organic light-emitting diode display or a microLED display in which light-emitting pixels are formed on a flexible substrate layer (e.g., a flexible layer of polyimide or a sheet of other flexible polymer). Flexible support layer(s) for display  14  may also be formed from flexible glass, flexible metal, and/or other flexible structures. Display cover layer  14 CG may be formed from polymer, glass, crystalline materials such as sapphire, other materials, and/or combinations of these materials. The thickness of layer  14 CG may be 100-200 microns, less than 250 microns, less than 150 microns, less than 100 microns, at least 50 microns, or other suitable thickness. 
     In the example of  FIG.  3   , housing  12  has a portion on rear face R that forms a rear housing wall and has side portions forming sidewalls  12 W. The rear housing wall of housing  12  may form a support layer for components in device  10 . Housing  12  may also have one or more interior supporting layers (e.g., frame structures) such as illustrative housing midplate  12 ′. Midplate  12 ′ may be formed from a layer of metal. Midplate  12 ′ may have first and second portions that are coupled to opposing sides of a hinge that is aligned with bend axis  28  (see, e.g., hinge  30  of  FIG.  2   ) or midplate  12 ′ may be sufficiently flexible to allow bending of midplate  12 ′ around bend axis  28 . 
     Electrical components  32  may be mounted in the interior of device  10  (e.g., between display  14  and the rear of housing  12 , between midplate  12 ′ and the opposing rear housing wall formed by housing  12  on rear face R, etc.). Components  32  may include circuitry of the type shown in  FIG.  1    (e.g., control circuitry  20 , communications circuitry  22 , input-output devices  24 , batteries, etc.). If desired, some or all of midplate  12 ′ may be omitted and/or additional internal support structures may be provided to strengthen device  10 . 
     Display  14  may be mounted on front face F of device  10 . When device  10  is folded about axis  28 , display cover layer  14 CG, display panel  14 P, and the other structures of device  10  that overlap bend axis  28  may flex and bend to accommodate folding. To relieve stresses that might otherwise tend to build up as the layers of display  14  are bent about axis  28  and/or as display  14  is subjected to a localized force from an external object during an impact event, device  10  may include spring layer  34 . Spring layer  34  may have spring structures that tend to dissipate applied force over a relatively large fraction of the area of front face F and thereby help display panel  14 P to deflect smoothly over a relatively large area when subjected to stress from bending about axis  28  or impact stress that arises when an external object bears against a particular location on the surface of display  14 . The ability of spring layer  34  to deflect smoothly in this way helps prevent excessive localized deformation that could lead to concentrated stress and damage to the thin-film circuitry and/or other components of display panel  14 P. The spring structures may, as an example, include springs that are formed from flexible metal (e.g., spring metal such as spring steel, nickel-chromium aluminum alloys, beryllium copper alloys, stainless steel, cobalt-nickel alloys, etc.). 
       FIG.  4    is a side view of device  10  showing how display panel  14 P may include a stack of layers  37 . Layers  37  may include polarizer layers, thin-film encapsulation layers, thin-film circuitry including pixel circuits for the pixels of panel  14 P, light-emitting diodes for the pixels of panel  14 P, and/or other display circuitry, flexible substrate layer(s), etc. Spring layer  34  may be interposed between display panel  14 P and support layer  40 . Layer  40  may be formed from a housing structure such as midplate  12 ′, a rear housing wall in housing  12 , and/or other support layer in device  10 . 
     A metal layer such as layer M may be formed as the lowermost layer of panel  14 P and/or a metal layer such as metal layer M may be formed from a separate layer that is attached to panel  14 P by a layer of adhesive. Spring layer  34  may be formed from an array of springs  36 . Springs  36  may be formed in a gap between layer M and layer  40  (e.g., an air-filled gap or a gap filled with liquid, gel, or other such material). Attachment structures  42  (e.g., welds, adhesive, solder, screws and/or other fasteners, engagement structures such as clips and snaps, press-fit connections, and/or other attachment mechanisms) may be used to attach springs  36  to layer M and/or layer  40 ). The size of gap  38  (e.g., distance D 2  between layer M and layer  40 , which is equal to the thickness of springs  36 ) may be 0.5 mm, 1.3 mm, 1.5 mm, 0.2-3 mm, at least 0.2 mm, at least 0.4 mm, at least 0.7 mm, at least 1 mm, at least 2 mm, less than 10 mm, less than 3 mm, less than 2.5 mm, less than 1.5 mm, less than 1 mm, or other suitable size. In an illustrative configuration, sufficient compression and support may be provided by springs of 0.5 mm in thickness. The pitch (center-to-center spacing DO of springs  36  may be 3 mm, 8 mm, 10 mm, 17 mm, at least 0.5 mm, 1-30 mm, at least 1 mm, at least 2 mm, at least 3 mm, at least 5 mm, at least 10 mm, at least 15 mm, at least 25 mm, less than 100 mm, less than 30 mm, less than 20 mm, less than 10 mm, less than 5 mm, less than 3 mm, less than 2 mm or other suitable value. To provide uniform support for display  14 , it may be desirable for the pitch of springs  36  to be less than 3 mm (as an example). 
       FIG.  5    is a graph in which compression modulus as a function of compression ratio is compared for illustrative display systems with and without spring layer  34 . Curve  43  corresponds to an illustrative display in which spring layer  34  has been replaced with a layer of compressible foam. Curve  44  corresponds to an illustrative display that is supported on spring layer  34 . When an external force is applied (e.g., localized downward force at a location on the surface of display  14 ), display  14  is pressed inwardly and compresses the underlying support structures in device  10 . As shown by comparing curves  43  and  44 , for a given amount of compression (compression ratio) for the display support layer, more strain energy is absorbed by the support layer when the support layer is formed by foam (curve  43 ) than with spring layer  34  (curve  44 ). This illustrates that the use of spring layer  34  in supporting at least some of display  14  in device  10  can help reduce the strain energy absorbed during an impact. Spring layer  34  helps redistribute stress by smoothing local deflection (e.g., by converting what would have been a deep localized depression from the impact into a larger-area shallow depression). If desired, spring layer  34  may include foam structures, springs of different heights, and/or other structures in addition to or instead of an array of springs  36  of the type shown in  FIG.  4   . 
       FIGS.  6  and  7    show how display  14  may be coupled to housing  12 . In the example of  FIG.  6   , which may sometimes be referred to as a fully constrained display mounting system, display cover layer  14 CG and display panel (display module)  14 P have been captured within an inwardly facing groove in housing sidewall  12 W, thereby helping these layers to resist vertical and horizontal movement within device  10  relative to housing  12 . In the example of  FIG.  7   , which may sometimes be referred to as a partially constrained display mounting system, foam, springs, or other compressible structures such as structures  46  have been placed above and below display cover layer  14 CG in the groove in sidewall  12 W. The outermost edge of display cover layer  14 CG is also recessed relative to sidewall  12 W. This arrangement allows display  14  to move somewhat relative to housing  12  and may help reduce impact strain for impacts close to the edge of display  14 . 
       FIGS.  8 - 11    are side views of illustrative spring arrangements for use in the array of springs  36  in spring layer  34 . As shown in  FIG.  8   , multiple different types of spring  36  may be used (e.g., springs with different stiffnesses, springs with different heights, springs with different diameters, springs of different shapes, sizes, and/or materials, etc.). A first set of springs  36  in layer  34  may, as an example, have a larger height HB and a second set of springs  36  may have a smaller height HL. In this type of configuration, the shorter springs are only activated when an impact produces a relatively large amount of inward force on display  14  (e.g., the shorter springs serve to provide additional spring power to handle impacts of large magnitudes). In the example of  FIG.  8   , springs of different types are located adjacent to each other.  FIG.  9    shows how springs of different types (e.g., springs of different heights) may be mounted in a coaxial arrangement.  FIG.  10    shows how a block of polymer foam or other non-spring compressible structure (see, e.g., foam posts  50 ) may be mounted coaxially with springs  36  or may be mounted adjacent to springs  36 . In the  FIG.  10    arrangement, foam structures such as foam posts  50  are shorter than spring  36  and thereby serve to provide additional support for display  14  and additional energy dissipation that helps display  14  recover when subjected to impacts with large amounts of force. If desired, posts  50  or other foam structures may have the same height as springs  36  (see, e.g.,  FIG.  11   ). 
     Springs  36  and/or other compressible structures such as foam structures may be distributed evenly across display  14  or may have different characteristics in different areas of display  14 . As shown in the cross-sectional side view of device  10  in  FIG.  12   , for example, layer  34  may have a first portion  34 - 1  in an area such as strip  52  that overlaps and runs along bend axis  28  and may have a second portion  34 - 2  in other areas  54 . Because portion  34 - 1  is adjacent to bend axis  28 , portion  34 - 1  may be subjected to more deflection than portions  34 - 2  as device  10  bends while being opened and closed. Accordingly, it may be desirable to form portion  34 - 1  from softer springs or springs that otherwise differ from the springs of portion  34 - 2 . In general, any suitable characteristics of portions  34 - 1  and  34 - 2  may differ from each other (e.g., spring shape, spring size, spring stiffness, spring pitch, foam type, foam shape and/or size, etc.). 
     Springs  36  may have spiral shapes, dome shapes, shapes based on spring arms, corrugated shapes, or other suitable shapes and may be formed individually and/or partly or completely attached to and/or integrally formed from a sheet of spring metal.  FIGS.  13 ,  14 ,  15 ,  16 , and  17    are diagrams of illustrative springs  36 . 
     In the example of  FIGS.  13  and  14   , spring  36  is a washer spring.  FIG.  13    is a side view of the washer spring showing how the washer spring may have portions of different heights at different locations around its periphery (e.g., the spring may have a wavy appearance when viewed from the side).  FIG.  14    is a top view of the illustrative washer spring of  FIG.  13    showing how the washer spring may have a ring shape with a circular footprint (outline when viewed from above). 
     If desired, a pressure sensor (sometimes referred to as a force sensor) such as pressure sensor  56  may be overlapped by spring  36  and aligned with spring  36  as shown in  FIG.  14    (e.g., sensor  56  may be located in a central circular opening of a ring-shaped spring). Sensors such as sensors  56  may also be located between adjacent springs  36 . Sensor  56  may be a capacitive force sensor, a piezoelectric force sensor, a resistive force sensor, a strain gauge, an optical sensor for measuring force, a sensor that measures displacement and/or movement in addition to or instead of measuring applied force, or any other suitable force sensor. 
     As shown in the side view of illustrative spring  36  of  FIG.  15   , spring  36  may have a hollow tubular shape (e.g., a hollow cylindrical shape). Spring  36  of  FIG.  15   , which may sometimes be referred to as a wave washer, may be formed from a hollow metal tube or other tube with flexibility-enhancement sidewall openings such as a series of diamond shaped openings or other perforations that provide spring  36  with axial flexibility (e.g., flexibility-enhancement sidewall openings). 
       FIGS.  16  and  17    are diagrams of an illustrative spring with spring arms. The side view of spring  36  of  FIG.  16    shows how the spring arms may extend upwardly from a central point.  FIG.  17    shows how the arms may be distributed around the circumference of spring  36  (e.g., spring arms  36 A may each be spaced apart from each other by 120°) and may extend radially outward from the center of the spring. There may be three arms  36 A, four arms  36 A, or other suitable number of arms  36 A. The configuration of  FIGS.  16  and  17    is illustrative. As shown in  FIG.  17   , a force sensors  56  may be formed on one or more of arms  36 A. The force sensor(s) of  FIG.  17    may be, for example, strain gauges formed from meandering metal traces on a dielectric layer on the surface of spring arm(s)  36 A. There may be one or more sensors  56  for each spring  36  in layer  34  or layer  34  may have fewer sensors  56  (e.g., only a subset of springs  36  may have associated sensors for measuring applied force). 
     During operation of device  10 , control circuitry  20  may gather information on the amount of applied force on display  14  using sensors  56 . Circuitry  20  may, for example, monitor sensors  56  to determine whether excessive force is applied to one or more areas of display  14 . If excessive force is detected, an alert may be generated (e.g., an audible or visible warning message), the amount of detected force may be logged in memory for future retrieval and analysis, and/or other suitable action may be taken. If desired, a user may press on display  14  to provide force input and the force sensors may be used to measure the force input. The force input may direct circuitry  20  to take action (e.g., force input may be used to select an on-screen item on display  14 , etc.). 
     Additional illustrative spring shapes are shown in  FIGS.  18 ,  19 ,  20 ,  21 , and  22   . 
     As shown in the top view of illustrative spring  36  of  FIG.  18   , spring  36  may have a circular outline with a central opening that has three radially extending slots. Spring  36  may have a wavy cross-sectional shape (e.g., spring  36  may form a washer spring), may have a dome shape, or may have other suitable spring shape that provides spring with a desired thickness. 
       FIG.  19    is a cross-sectional side view of an illustrative  2 D wave spring.  FIG.  19    shows how springs  36  may be formed by corrugations in a layer of metal. The corrugated spring structure of  FIG.  19    has alternating ridges and grooves. The ridges and grooves may extend parallel to each other across display  14  (e.g., into the page in the example of  FIG.  19   ). 
     The top view of spring  36  of  FIG.  20    shows how spring  36  may have a hexagon pyramid spring arrangement. As shown in  FIG.  20   , spring  36  may have a hexagonal central portion with radially extending and meandering spring arms. The arms extend out of the page of  FIG.  20    to provide spring  36  with a desired thickness. 
     As shown by the top view of illustrative spring  36  of  FIG.  21   , spring  36  may have a circular patch surrounded by curved arms. In the example of  FIG.  21   , spring  36  has two arms, each of which runs along an opposing curved edge of the circular patch. If desired, this type of spring may have three or more curved arms. The arms of spring  36  of  FIG.  21    are angled out of the page of  FIG.  21    (e.g., at an angle of 5-30° or other suitable angle) so that spring  36  has a desired thickness. 
       FIG.  22    is a top view of spring  36  in an illustrative cantilever spring configuration. Portion  36 F of spring  36  may be flat and lie parallel to display  14 . Arm  36 P of spring  36  may be angled slightly out of the page of  FIG.  22    to provide spring  36  with a desired thickness. 
       FIG.  23    is a cross-sectional side view of an illustrative spring coupled to metal layer M. As shown in  FIG.  23   , spring  36  may be coupled to layer M using attachment structures  42 . Structures  42  may include, for example, a weld that attaches an arm or other portion of spring  36  to layer M at one location and adhesive that attaches one or more additional arms (or other portions) of spring  36  to layer M at one or more additional locations. The use of adhesive may provide the additional arms with the ability to move laterally under layer M when compressed. Optional foam post  50  may be used to help dissipate impact energy when display  14  is impacted by an external object. A force sensor (e.g., sensor  56 ) may, if desired, be formed on one of the surfaces of spring  36  and/or may be located adjacent to or under spring  36  to help measure applied force to spring layer  34 . 
     As described in connection with  FIGS.  13 ,  14 ,  15 ,  16 , and  17   , springs may be formed as stand-alone elements or may be formed as integral portions of a sheet of metal or other spring material. As an example, springs with sets of three radially extending spring arms such as springs  36  of  FIGS.  16  and  17    may be formed in an array on a sheet of metal as shown by illustrative springs  36  in metal sheet  36 M of  FIG.  24   . Each spring  36  of  FIG.  24    has three radially extending arms. The arms are separated from each other by 120° and are attached at their bases to metal sheet  36 M. Each spring arm is bent upwards at its tip (out of the plane of  FIG.  24   ) to form spring  36 , as shown in the cross-sectional side view of spring  36  of  FIG.  16   . Laser cutting, drilling, water jet cutting, stamping, and/or other fabrication techniques may be used to form sheets of springs  36  having the illustrative shapes of  FIG.  24    and/or other suitable spring shapes (see, e.g.,  FIGS.  13 ,  14 ,  15 ,  16 , and  17   , etc.). 
     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: 20210730
Publication Date: 20240416
Grant Date: 20240416
Priority Date: 20200910
Inventors: HUANG, CHANG-CHIA
KIM, HOON SIK
DRZAIC, PAUL S.
Lam, Terry C.
AFSAR, YASMIN F.
SHAO, ZHICHUN
Assignee: APPLE INC
CPC Classifications: [{"code": "H10H20/8506", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L33/483", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10272", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M1/0214", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0268", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/167", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10272", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 80470993