PATENT DOCUMENT

Publication Number: US-11275475-B2
Application Number: US-202117141658-A
Country: US
Kind Code: B2

Title: Compliant material for protecting capacitive force sensors and increasing capacitive sensitivity

Abstract:
A compliant material, such as a conductive foam, is positioned in the dielectric or capacitive gap between drive and sense electrodes and/or other conductive elements of a capacitive and/or other force sensor, such as a TFT or other display element and a sensor assembly. The compliant material prevents damage by preventing and/or cushioning contact. The compliant material may be conductive. By being conductive and being positioned between the electrodes while still being separated from one or more of the electrodes, the compliant material also shortens the effective electrical distance between the electrodes. As a result, the force sensor may be more sensitive than would otherwise be possible while being less vulnerable to damage.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 an electronic component coupled to the housing; 
 an electrode positioned within the housing and capacitively coupled to the electronic component across an air gap defined between the electrode and the electronic component; 
 a processing unit operative to estimate an amount of a force that deforms the electronic component based, at least in part, on a change in capacitance between the electronic component and the electrode; and 
 a conductive compliant material positioned in the housing within the air gap between the electronic component and the electrode. 
 
     
     
       2. The electronic device of  claim 1 , wherein the electronic component is operable to contact the conductive compliant material during deformation. 
     
     
       3. The electronic device of  claim 1 , wherein the electronic component remains separate from the conductive compliant material during deformation. 
     
     
       4. The electronic device of  claim 1 , wherein the conductive compliant material is coupled to at least one of:
 the electronic component; or 
 the electrode. 
 
     
     
       5. The electronic device of  claim 1 , further comprising a midplate coupled to the housing between the electrode and the electronic component wherein the conductive compliant material is coupled to the midplate. 
     
     
       6. The electronic device of  claim 1 , wherein the conductive compliant material is coupled to the electrode by a conductive adhesive. 
     
     
       7. The electronic device of  claim 1 , further comprising an insulating material coating the conductive compliant material. 
     
     
       8. An electronic device, comprising:
 a component that defines an external surface of the electronic device; 
 a force sensor that is operable to measure a force exerted on the component that changes a capacitive gap of the force sensor, the force sensor including a first electrode coupled to the component and a second electrode coupled to a substrate across an air gap; and 
 a compliant material positioned in the air gap that:
 includes a conductive portion; and 
 absorbs at least a portion of the force. 
 
 
     
     
       9. The electronic device of  claim 8 , wherein the compliant material comprises the conductive portion and a nonconductive portion. 
     
     
       10. The electronic device of  claim 8 , wherein the compliant material includes:
 a first conductive material connected to the second electrode of the force sensor; and 
 a second conductive material that functions as a shield electrode. 
 
     
     
       11. The electronic device of  claim 10 , wherein the compliant material further includes insulating material separating the first conductive material and the second conductive material. 
     
     
       12. The electronic device of  claim 8 , wherein the compliant material comprises at least one of:
 a conductive foam; 
 a silicone gasket; 
 an air loop gasket; 
 a fabric; or 
 a conductive adhesive. 
 
     
     
       13. The electronic device of  claim 8 , wherein the compliant material is compressible. 
     
     
       14. The electronic device of  claim 8 , wherein the compliant material has a thickness of 250-950 microns. 
     
     
       15. An electronic device, comprising:
 a housing; 
 a first electrode that is operable to deform when a force is exerted; 
 a second electrode that is separated from the first electrode by a gap; 
 a processing unit that is operable to detect a change in capacitance between the first electrode and the second electrode when the first electrode deforms; and 
 a conductive compliant material positioned in the gap and electrically connected to a first of the first electrode and the second electrode, the conductive compliant material separated from a second of the first electrode and the second electrode in an absence of the force and contacted by the second of the first electrode and the second electrode when the force is exerted. 
 
     
     
       16. The electronic device of  claim 15 , wherein the first of the first electrode and the second electrode is resistively coupled to the conductive compliant material. 
     
     
       17. The electronic device of  claim 15 , wherein the first of the first electrode and the second electrode is capacitively coupled to the conductive compliant material. 
     
     
       18. The electronic device of  claim 15 , further comprising a shield electrode capacitively coupled to the conductive compliant material. 
     
     
       19. The electronic device of  claim 18 , further comprising a nonconductive material separating the shield electrode and the conductive compliant material. 
     
     
       20. The electronic device of  claim 19 , wherein the nonconductive material separates the first of the first electrode and the second electrode and the conductive compliant material.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/399,958, filed Apr. 30, 2019, the contents of which are incorporated herein by reference as if fully disclosed herein. 
    
    
     FIELD 
     The described embodiments relate generally to force sensors. More particularly, the present embodiments relate to compliant materials that can protect capacitive force sensors and increase capacitive sensitivity. 
     BACKGROUND 
     Electronic devices are increasingly prevalent. These electronic devices use a wide variety of different components to obtain input. Examples of such input components include, but are not limited to, keyboards, virtual keyboards, computer mice, speakers, microphones, displays, touch surfaces, touch sensors, force sensors, buttons, sliders, dials, and so on. 
     Electronic devices are also increasingly portable. Portability may limit the kinds and/or number of input components that may be used in an electronic device. This may put demands on the input components that remain to distinguish among more different kinds of input, increase performance and/or sensitivity, and so on. 
     SUMMARY 
     The present disclosure relates to a compliant material for protecting capacitive force sensors and increasing capacitive sensitivity. A compliant material, such as a conductive foam, may be positioned in the dielectric gap between drive and sense electrodes and/or other conductive elements of a capacitive and/or other force sensor, such as a TFT or other display element and a sensor assembly. The compliant material may prevent damage by preventing and/or cushioning contact. The compliant material may be conductive. By being conductive and being positioned between the electrodes while still being separated from one or more of the electrodes, the compliant material may also shorten the effective electrical distance between the electrodes. As a result, the force sensor may be more sensitive than would otherwise be possible while being less vulnerable to damage. 
     In various embodiments, an electronic device includes a housing; a display coupled to the housing and configured to receive a force, further configured to deform in response to the force; a sense electrode positioned within the housing and capacitively coupled to the display across an air gap defined between the sense electrode and the display; a processing unit operative to estimate an amount of the force based, at least in part, on a change in capacitance between the display and the sense electrode; and a conductive compliant material. The conductive compliant material is positioned in the housing within the air gap between the display and the sense electrode. 
     In some examples, the display is operable to contact the conductive compliant material during deformation. In other examples, the display remains separate from the conductive compliant material during deformation. 
     In a number of examples, the conductive compliant material is coupled to at least one of the display or the sense electrode. In some examples, the electronic device further includes a midplate coupled to the housing between the sense electrode and the display wherein the conductive compliant material is coupled to the midplate. In various examples, the conductive compliant material is coupled to the sense electrode by a conductive adhesive. In a number of examples, the electronic device further includes an insulating material coating the conductive compliant material. 
     In some embodiments, an electronic device includes a cover; a force sensor that is operable to measure a force exerted on the cover that changes a capacitive gap of the force sensor, the force sensor including a display component coupled to the cover and a sensor assembly coupled to a substrate across an air gap; and a compliant material positioned in the air gap. The compliant material includes a conductive portion, decreases an effective electrical distance of the capacitive gap, and prevents damage to the force sensor by absorbing at least a portion of the force. 
     In various examples, the compliant material includes the conductive portion and a nonconductive portion. In some examples, the compliant material includes a first conductive material connected to a sensing electrode of the force sensor and a second conductive material that functions as a shield electrode. In various implementations of such examples, the compliant material further includes insulating material separating the first conductive material and the second conductive material. 
     In some examples, the compliant material includes at least one of a conductive foam, a silicone gasket, an air loop gasket, a fabric, or a conductive adhesive. In a number of examples, the compliant material is compressible. In various examples, the compliant material has a thickness of approximately 250-950 microns. 
     In a number of embodiments, an electronic device includes a housing; a drive electrode that is operable to deform when a force is exerted; a sense electrode that is operable to detect a change in capacitance when the drive electrode deforms, the sense electrode separated from the drive electrode by a gap; and a conductive compliant material. The conductive compliant material is positioned in the gap and electrically connected to the sense electrode, the conductive compliant material separated from the drive electrode in the absence of the force and contacted by the drive electrode when the force is exerted. 
     In some examples, the sense electrode is resistively coupled to the conductive compliant material. In other examples, the sense electrode is capacitively coupled to the conductive compliant material. 
     In various examples, the electronic device further includes a shield electrode capacitively coupled to the conductive compliant material. In some implementations of such examples, the electronic device further includes a nonconductive material separating the shield electrode and the conductive compliant material. In various such examples, the nonconductive material separates the sense electrode and the conductive compliant material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements. 
         FIG. 1  depicts an example electronic device that uses a compliant material to protect and/or increase sensitivity in capacitive force sensors. 
         FIG. 2A  depicts an example cross section of the example electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . 
         FIG. 2B  shows the example electronic device of  FIG. 2A  when a force applied to the cover deforms the display. 
         FIG. 3  depicts example clearances between the compliant material and the sides of the aperture in the first structural element of  FIG. 1  with other components removed for clarity. 
         FIG. 4A  depicts a first example of a compliant material and sensor assembly stack that may be used in the example electronic device of  FIG. 2A . 
         FIG. 4B  depicts a second example of a compliant material and sensor assembly stack that may be used in the example electronic device of  FIG. 2A . 
         FIG. 4C  depicts a third example of a compliant material and sensor assembly stack that may be used in the example electronic device of  FIG. 2A . 
         FIG. 5  depicts a first alternative example of the example electronic device of  FIG. 2A . 
         FIG. 6A  depicts a second alternative example of the example electronic device of  FIG. 2A . 
         FIG. 6B  shows the example electronic device of  FIG. 6A  when a force applied to the cover deforms the display. 
         FIG. 7  depicts a third alternative example of the example electronic device of  FIG. 2A . 
         FIG. 8  depicts a fourth alternative example of the example electronic device of  FIG. 2A . 
         FIG. 9  depicts a fifth alternative example of the example electronic device of  FIG. 2A . 
         FIG. 10  depicts a sixth alternative example of the example electronic device of  FIG. 2A . 
         FIG. 11  depicts a seventh alternative example of the example electronic device of  FIG. 2A . 
         FIG. 12  depicts a first example of a compliant material assembly that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . 
         FIG. 13A  depicts a second example of a compliant material assembly that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . 
         FIG. 13B  depicts a third example of a compliant material assembly that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . 
         FIG. 14  depicts a fourth example of a compliant material and sensor assembly stack that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . 
         FIG. 15  depicts a fourth example of a compliant material assembly that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . 
         FIG. 16  depicts example functional relationships between example components that may be used to implement the example electronic devices of  FIGS. 2A and/or 5-7 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The description that follows includes sample systems, methods, and computer program products that embody various elements of the present disclosure. However, it should be understood that the described disclosure may be practiced in a variety of forms in addition to those described herein. 
     Many sensors that can be used to detect touch and/or force include conductive elements separated by a dielectric or capacitive gap, such as an air gap. Applied force may cause one or more of the conductive elements to deform into the dielectric gap, changing a capacitance or resistance between the conductive elements. Changes in capacitance or resistance between the conductive elements may be measured to detect one or more inputs, estimate a non-binary amount of an applied force, estimate a location of a touch or applied force, and so on. 
     The sensitivity of such a sensor may depend on various factors. These factors may include the size and/or the area of the conductive elements, the proximity of the conductive elements to each other, and so on. Such sensors may be most sensitive when the conductive elements are as large as possible and as close to each other as possible. The size and/or the area of the conductive elements may be limited by the constraints of an electronic device in which the sensor is incorporated. For example, the size and/or the area of the conductive elements may be constrained by a housing of the electronic device, placement of other components within the electronic device, and so on. The factor that is most easily controlled may be the proximity of the conductive elements to each other. 
     However, the conductive elements may be subject to damage. The conductive elements may be damaged when an applied force causes one or more of the conductive elements to contact the other (or “bottom out”). In some implementations, one or more of the conductive elements may be particularly fragile, such as when such a thin-film-transistor (TFT) component or other conductive component (such as a metal component, indium tin oxide component, and so on) of a liquid crystal display (LCD) and/or other display (such as a light-emitting diode or LED display, an organic LED or OLED display, a cathode ray tube or CRT display, an electroluminescent display or ELD, a plasma display panel or PDP, an active-matrix OLED or AMOLED display, a quantum dot or QLED display, and so on) and/or sensor (such as one or more touch sensors, force sensors, thin film sensors, and so on) in a display stack. Likewise, one or more of the conductive elements may be a system-in-a-package (SIP) or other integrated circuit (IC) that includes an electrode that the SIP may use to estimate the location and/or non-binary amount of a force applied to the display and/or cover (though in some implementations the SIP may instead perform a binary determination as to whether a force and/or a threshold amount of force is applied, such as to emulate a button click/not-clicked experience), cover glass, and/or or other surface coupled thereto. The display and/or SIP may be damaged if an impact, force, or other occurrence causes the display and/or component thereof to contact the SIP and/or component thereof. Such damage may impair and/or disable operation of one or more components and may be expensive and/or difficult to repair, perhaps involving replacement of the component and/or device in which the component is incorporated. 
     The following disclosure relates to a compliant material for protecting capacitive force sensors and increasing capacitive sensitivity. A compliant material, such as a conductive foam, may be positioned in the dielectric or capacitive gap between drive and sense electrodes and/or other conductive elements of a capacitive and/or other force sensor, such as a TFT or other display element and a sensor assembly. The compliant material may prevent damage by preventing and/or cushioning contact. The compliant material may be conductive. By being conductive and being positioned between the electrodes while still being separated from one or more of the electrodes, the compliant material may also shorten the effective electrical distance between the electrodes. As a result, the force sensor may be more sensitive than would otherwise be possible while being less vulnerable to damage. 
     These and other embodiments are discussed below with reference to  FIGS. 1-16 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  depicts an example electronic device  100  that uses a compliant material to protect and/or increase sensitivity in capacitive force sensors. The electronic device  100  may include a housing  101  and a cover  102  and/or other cover glass or touch surface. Although the electronic device  100  is shown as a portable computing device, it is understood that this is an example. In various implementations, the electronic device  100  may be any kind of electronic device, such as a desktop computing device, a laptop computing device, a mobile computing device, a tablet computing device, a smart phone, a digital media player, a wearable device, a kitchen appliance, a vehicle, and so on without departing from the scope of the present disclosure. 
       FIG. 2A  depicts an example cross section of the example electronic device  100  of  FIG. 1 , taken along line A-A of  FIG. 1 . The electronic device  100  may include a display  210  that may include one or more conductive components  211  (which may be a metal component, indium tin oxide component, and so on, such as an LCD that includes a TFT component), a sensor assembly  213  or sensing that may include one or more sense electrodes, and a compliant material  214  that is disposed in a dielectric or capacitive gap  212  (such as an air gap, which may be approximately 1.8 mm in the absence of force applied to the cover  102 ) between the conductive component  211  and/or the display  210  and the sensor assembly  213 . The compliant material  214  may be conductive. 
     The conductive component  211  and the sensor assembly  213  may form a force sensor that the electronic device  100  may use to estimate a touch, a force, a location of a force, and/or a non-binary amount of a force and so on applied to the cover  102 . For example, the electronic device  100  may estimate such using a change in a capacitance and/or resistance between the conductive component  211  and the sensor assembly  213  that may change as the conductive component  211  and/or the cover  102  and/or the display  210  deforms with respect to the sensor assembly  213 , as shown in  FIG. 2B . By way of illustration, the conductive component  211  may be driven with one or more voltages as a drive electrode and one or more electrodes of the sensor assembly  213  may be monitored as one or more sense electrodes to determine one or more capacitances and/or changes in capacitance between the one or more drive and sense electrodes. 
     In the absence of the compliant material  214 , the sensor assembly  213  could possibly contact the bottom of the display  210 , thus potentially damaging either the sensor assembly  213  and/or any sensitive component in the display  210 . As such, the compliant material  214  may prevent damage by preventing and/or cushioning contact between the display  210  and the sensor assembly  213 . This may result in a “soft bottom out.” For example, the compliant material  214  may compress and/or otherwise deform to absorb force. As discussed above, the compliant material  214  may be conductive. By being conductive and being positioned between the conductive component  211  and/or the display  210  and the sensor assembly  213  while still being separated from one or more of the conductive component  211  and the sensor assembly  213 , the compliant material  214  may also shorten the effective electrical distance between the conductive component  211  and the sensor assembly  213 . As a result, the force sensor including the conductive component  211  and the sensor assembly  213  may be more sensitive than would otherwise be possible while being less vulnerable to damage. 
     The compliant material  214  may be formed of a variety of different materials. In some examples, the compliant material  214  may be a conductive foam (such as an acrylic foam, an acrylic based foam, a foam doped with nickel and/or other metals, an acrylic pressure sensitive adhesive foam, an open cell foam, a closed cell foam, a polymer foam, a microcellular polymer foam, a polyurethane foam, a melamine foam, a foam sold under the brand name Singleton Shieldite EM-PO070S or similar thereto, a foam sold under the brand name Singleton Shieldite EM-PO050S or similar thereto, a foam sold under the brand name Rogers Condux Plus 0.3 or similar thereto, a foam sold under the brand name Rogers Condux Plus 0.3 or similar thereto, a foam sold under the brand name 3M MSG7060S or similar thereto, and so on). In a number of examples, open cell foams may have advantages over closed cell foams as air pockets in closed cell foams may result in drift (such as mechanical drift, temperature drift, and so on). Harder foams may have the advantage of more rigidity whereas softer foams may have the advantage of greater compressibility. In various examples, the compliant material  214  may be a conductive fabric. In other examples, the compliant material  214  may be a conductive gel. In still other examples, the compliant material  214  may be a conductive elastomer. In yet other examples, the compliant material  214  may be a silicone gasket, an air loop gasket, a conductive adhesive, and/or other conductive materials that are compliant. In a number of examples, the compliant material  214  may be an assembly of a number of different conductive and nonconductive materials. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     The compliant material  214  may have a variety of different thicknesses. For example, the compliant material  214  may have a thickness of 330 μm, 650 μm, 800 μm, and so on. The thickness of the compliant material  214  may correspond to an amount that the compliant material  214  is operable to compress when contacted by the display  210  and/or other component when a force is exerted, an impact occurs, and so on. For example, a compliant material  214  having a thickness of 800 μm may be operative to compress up to approximately 33% when contacted by the display  210  and/or other component when a force is exerted, an impact occurs, and so on. By way of another example, a compliant material  214  with a thickness of 650 μm may be operative to compress up to approximately 17% when contacted by the display  210  and/or other component when a force is exerted, an impact occurs, and so on. In yet another example, a compliant material  214  with a thickness of 330 μm may be sufficiently thin that the compliant material  214  is not contacted by the display  210  and/or other component when a force is exerted, an impact occurs, and so on. Sensitivity may increase as thickness increases. Further, greater thicknesses may allow for lower force noise in force sensor applications. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     The electronic device  100  may also include a substrate  215  and/or other component that electrically, mechanically, communicably, and/or otherwise connects the sensor assembly  213  to one or more other components. For example, the substrate may be a main logic board and/or other printed circuit board, flexible circuit, and so on. 
     The electronic device  100  may further include one or more conductive components (such as components formed of metal and/or other conductive materials) that may be disposed between various portions of the display  210 , the conductive component  211 , the compliant material  214 , and/or the sensor assembly  213 . Such conductive components may be configured so as to not interfere with the force sensor. 
     For example, the electronic device  100  may include a first structural element  216  that is configured as a midplate to provide rigidity and/or other structural support to the housing  101 . By way of another example, the electronic device  100  may include a second structural element  218  that is configured as a cowl to restrain one or more wires and/or other components to the substrate  215 . The first structural element  216  may be formed metal and/or include one or more metal portions and may define one or more apertures  217  to provide clearance between one or more edges of the first structural element  216  and the compliant material  214  and/or the sensor assembly  213  to prevent electrical interference. Similarly, the second structural element  218  may be formed metal and/or include one or more metal portions and may define one or more apertures  219  to provide clearance between one or more edges of the second structural element  218  and the compliant material  214  and/or the sensor assembly  213  to prevent electrical interference. 
     By way of illustration,  FIG. 3  depicts example clearances  421  and  422  between the compliant material  214  and the sides of the aperture  217  in the first structural element  216  of  FIG. 1  with other components removed for clarity. These clearances  421  and  422  may prevent the first structural element  216  from electrically interfering with a capacitance and/or a resistance between the conductive component  211  and the sensor assembly  213  of  FIG. 2A . 
     Returning to  FIG. 2A , the first structural element  216  and/or the second structural element  218  may be optional. In various implementations, the electronic device  100  may function without the first structural element  216  and/or the second structural element  218 . The first structural element  216  and/or the second structural element  218  may function as a shield to prevent damage to the display  210  to prevent the display  210  from bottoming out against the sensor assembly  213  and/or another component, resulting in damage to the display  210 . The first structural element  216  and/or the second structural element  218  may be omitted in some implementations where components below the display  210  are otherwise cushioned by another mechanism and/or are spaced sufficiently far from the display  210  to avoid damage to the display  210  from bottoming out. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     In some examples, the aperture  217  in the first structural element  216  and/or the aperture  219  in the second structural element  218  may be omitted. For example, if the first structural element  216  and/or the second structural element  218  are formed of one or more nonconductive materials, the aperture  217  in the first structural element  216  and/or the aperture  219  in the second structural element  218  may be omitted. By way of another example, if the sensor assembly  213  is not configured to sense movement and/or deformation of the conductive component  211  and/or another component of the display  210 , the aperture  217  in the first structural element  216  and/or the aperture  219  in the second structural element  218  may be omitted. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     In this example, the compliant material  214  is shown as coupled to the sensor assembly  213 . However, it is understood that this is an example. In various implementations, the compliant material  214  may instead be coupled to the display  210 , to an intermediate component between the display  210  and the sensor assembly  213 , and so on. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     Further, in this example, the conductive component  211  is shown as a TFT component and the display  210  is shown as an LCD. However, it is understood that this is an example. In various implementations, the conductive component  211  may be any kind of conductive component of any kind of display, such as an LED display, an OLED display, a CRT display, an ELD, a PDP, an AMOLED display, a QLED display, and so on. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 4A  depicts a detail of a cross section side view of a first example of a compliant material  214  and sensor assembly  213  stack that may be used in the example electronic device  100  of  FIG. 2A . In this example, the sensor assembly  213  may include a sense electrode  423  and a ground electrode  424 . The ground electrode  424  may be formed from two layers  461 A,  461 B of copper or other conductive material connected through a layer of nonconductive material  462 . However, it is understood that this is an example and that in other implementations the ground electrode  424  may be formed of a single layer, three or more layers, and so on without departing from the scope of the present disclosure. The ground electrode  424  may be physically coupled to the compliant material  214  via a layer of nonconductive material  425 , such as a solder mask. As such, the ground electrode  424  may be capacitively coupled to the compliant material  214  to form a capacitor. The sense electrode  423  may be physically coupled to the compliant material  214 . As such, the sense electrode  423  may be resistively coupled to the compliant material  214 . This may be referred to as an “open configuration.” Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 4B  depicts a cross section side view of a second example of a compliant material  214  and sensor assembly  213  stack that may be used in the example electronic device  100  of  FIG. 2A . Similar to  FIG. 4A , in this example, the sensor assembly  213  may include a sense electrode  423  and a ground electrode  424 . Unlike  FIG. 4A , the sense electrode  423  may be physically coupled to the compliant material  214  via the layer of nonconductive material  425 . As such, both the ground electrode  424  and the sense electrode  423  may be capacitively coupled to the compliant material  214 , forming two capacitors. This may be referred to as a “closed configuration.” This closed configuration may have a signal degradation compared to the open configuration of  FIG. 4A , but may be less vulnerable to shorting. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 4C  depicts a cross section side view of a third example of a compliant material  214  and sensor assembly  213  stack that may be used in the example electronic device  100  of  FIG. 2A . Similar to  FIG. 4A , in this example, the sensor assembly  213  may include a sense electrode  423  and a ground electrode  424 . Unlike  FIG. 4A , the ground electrode  424  may be separated from the compliant material  214  such that the ground electrode  424  is not capacitively or resistively coupled to the compliant material  214 . This arrangement may not be subject to the coupling resistance modulation to which  FIG. 4A  may be vulnerable and may avoid signal loss through the capacitive divider which the nonconductive material  425  may function as between the two capacitors. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 5  depicts a first alternative example of the example electronic device  100  of  FIG. 2A . As discussed above, the compliant material  214  of the electronic device  100  may be configured with a variety of different thicknesses. The electronic device  500  of  FIG. 5  illustrates a first alternative where a compliant material  514  is thicker than the compliant material  214  of the electronic device  100 . For example, the compliant material  514  may have a thickness of 650 μm whereas the compliant material  214  of the electronic device  100  may have a thickness of 330 μm. 
     Similarly,  FIG. 6A  depicts a second alternative example of the example electronic device  100  of  FIG. 2A  where a compliant material  614  of the electronic device  600  is thicker than both the compliant material  214  of the electronic device  100  of  FIG. 2A  and the compliant material  514  of the electronic device  500  of  FIG. 5 . For example, the compliant material  614  may have a thickness of 800 μm whereas the compliant material  214  of the electronic device  100  may have a thickness of 330 μm and the compliant material  514  may have a thickness of 650 μm. The thicker the compliant material  614 , the more that the effective electrical distance between the conductive component  611  and the sensor assembly  613  within the dielectric or capacitive gap  612  may be decreased.  FIG. 6B  shows the example electronic device  600  of  FIG. 6A  when a force applied to the cover  602  deforms the display  610  such that the bottom of the display  610  contacts and deforms the compliant material  614 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     Returning to  FIG. 2A , the display  210  is illustrated and described above as an LCD and the conductive component  211  is illustrated and described above as a TFT component. However, as discussed above, the display  210  may be any other kind of display and the conductive component  211  may be another kind of conductive component of such a display without departing from the scope of the present disclosure. 
     By way of example,  FIG. 7  depicts a third alternative example of the example electronic device  100  of  FIG. 2A . The electronic device  700  may include an OLED display  710  that has one or more layers, such as a conductive component layer  711 . A sensor assembly  713  may be operative to detect changes in capacitance and/or resistance between one or more electrodes included therein and the conductive component layer  711  across a dielectric or capacitive gap  712 . Similar to the electronic device  100  of  FIG. 2A , a compliant material  714  may be coupled to the sensor assembly  713 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     Returning to  FIG. 2A , the compliant material  214  is illustrated and described as coupled to the sensor assembly  213 . However, it is understood that this is an example. In various implementations, the compliant material  214  may be otherwise positioned between the display  210  and the sensor assembly  213  without departing from the scope of the present disclosure. 
     By way of a first example,  FIG. 8  depicts a fourth alternative example of the example electronic device  100  of  FIG. 2A . The electronic device  800  may include a compliant material  814  coupled to a display  810 . Similar to the electronic device  100  of  FIG. 2A , a sensor assembly  813  may be operative to detect changes in capacitance and/or resistance between one or more electrodes included therein and a conductive component  811  of the display  810  across a dielectric or capacitive gap  812 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     By way of a second example,  FIG. 9  depicts a fifth alternative example of the example electronic device  100  of  FIG. 2A . The electronic device  900  may include a compliant material  914  coupled to a structural element  916  over an aperture  917  via a nonconductive connector  930 . As shown, the compliant material  914  may be coupled to the nonconductive connector  930  over a sensor assembly  913 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     By way of a third example,  FIG. 10  depicts a sixth alternative example of the example electronic device  100  of  FIG. 2A . The electronic device  1000  may include a compliant material  1014  coupled to a structural element  1016  over an aperture  1017  via a nonconductive connector  1030 . As contrasted with the electronic device  900  of  FIG. 9 , the nonconductive connector  1030  may separate the compliant material  1014  from a sensor assembly  1013  and position the compliant material  1014  partially and/or fully within the aperture  1017 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     As contrasted with the example implementations of  FIGS. 2 and 5-8 , the example implementations of  FIGS. 9 and 10  may have two gaps between the respective electrodes and the compliant materials  914 ,  1014  instead of just one where signal magnitude may modulate as 1/x in each gap. As a result, it may be challenging to accurately estimate non-binary amounts of applied force and/or other analog force sensor applications. However, this may not be an issue in implementations where determinations are made as to whether or not force is applied as thresholds for determining such using forces expected to be applied may be set accordingly. 
     By way of a fourth example,  FIG. 11  depicts a seventh alternative example of the example electronic device  100  of  FIG. 2A . Contrasted with the electronic device  100  of  FIG. 2A , the electronic device  1100  may include a compliant material  1114  separated from a structural element  1116  that does not define an aperture. In this example, the structural element  1116  may be formed of nonconductive materials so as not to interfere with a force sensor included in the electronic device  1100 . Alternatively, such a force sensor may detect capacitance changes between the structural element  1116  and one or more electrodes. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     Returning to  FIG. 2A , although the compliant material  214  is illustrated and described as a single piece of material, it is understood that this is an example. However, other configurations are possible and contemplated without departing from the scope of the present disclosure. 
     By way of illustration,  FIG. 12  depicts a side view of a first example of a compliant material assembly  1214  that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . The compliant material assembly  1214  may include conductive foam  1231  that is used as a sensing electrode and is coupled to conductive adhesive  1232 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 13A  depicts a second example of a compliant material assembly  1314  that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 .  FIG. 13A  shows a top view of the compliant material assembly  1314 , whereas the compliant material  214  may be illustrated from a side view in  FIG. 2A . The compliant material assembly  1314  may include an inner area of conductive foam  1333 A that is used as a sensing electrode and is separated from an outer area of conductive foam  1333 A that is used as a shield by insulating nonconductive foam  1334 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 13B  depicts a side view of a third example of a compliant material assembly  1314  that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . The compliant material assembly  1314  may include one or more areas of conductive foam  1333 A, one or more areas of insulating nonconductive foam  1334 , and conductive adhesive  1332 . In some implementations,  FIG. 13B  may illustrate a cross section of  FIG. 13A , such as taken along a line across the middle of  FIG. 13A  from left to right. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 14  depicts a fourth example of a compliant material  1414  and sensor assembly  1413  stack that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . A sensing electrode  1452  and a shield  1451  may be configured on a stack of materials that form the compliant material  1414 . The sensing electrode  1452  and/or the shield  1451  may be formed of compliant conductive material and may be positioned, separated by nonconductive material  1463 , on an arrangement of nonconductive foam  1434  and compressible vias  1433 . As such, the nonconductive foam  1434  may act as a base material similar to the base material of a printed circuit board. 
     The compressible vias  1433  may be connected to an anisotropic conductive adhesive  1432  that may in turn be connected to a drive and/or sense connector  1442  and a shield connector  1441 . The drive and/or sense connector  1442  and the shield connector  1441 , which may be separated by air gaps  1464  and/or nonconductive material in place of such air gaps  1464 , may connect the anisotropic conductive adhesive  1432  to a sensor assembly  1413 , which may be a SIP. The anisotropic conductive adhesive  1432  may be conductive only in the direction between the compressible vias  1433  and the drive and/or sense connector  1442  and the shield connector  1441  so that the drive and/or sense connector  1442  and the shield connector  1441  may be electrically isolated from each other. 
       FIG. 15  depicts a fourth example of a compliant material assembly  1514  that may be used in the example electronic devices of  FIGS. 2A and/or 5-7 . The compliant material assembly  1514  may include conductive foam  1533  that is coupled to conductive adhesive  1532  and coated with a nonconductive coating  1560 . Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
       FIG. 16  depicts example functional relationships between example components that may be used to implement the example electronic devices  100 ,  500 ,  600 ,  700  of  FIGS. 2A and/or 5-7 . For example, the electronic device  100  may include one or more processing units  1671  and/or other processors or controllers, one or more non-transitory storage media  1672  (which may take the form of, but is not limited to, a magnetic storage medium; optical storage medium; magneto-optical storage medium; read only memory; random access memory; erasable programmable memory; flash memory; and so on), one or more input and/or output devices  1673  (such as one or more microphones, speakers, keyboards, virtual keyboards, computer mice, track pads, track balls, touch surfaces, and so on), one or more displays  210 , one or more sensor assemblies  213 , and so on. 
     The processing unit  1671  may execute one or more instructions stored in the storage medium  1672  to perform various functions. Examples of such functions include, but are not limited to, performing one or more methods involving techniques of the present disclosure, detecting one or more capacitances and/or resistances between one or more conductive components of the display and/or electrodes of the sensor assembly  213  and/or changes in such capacitances and/or resistances, detecting one or more inputs using such changes in such capacitances and/or resistances, estimating one or more non-binary amounts of one or more applied forces using such changes in such capacitances and/or resistances, determining application of one or more forces and/or threshold amounts of forces using such changes in such capacitances and/or resistances (such as to emulate a button click/not-clicked experience), estimating one or more locations of one or more touches or applied forces using such changes in such capacitances and/or resistances, interpreting estimated applied forces as one or more inputs, interpreting estimated locations of applied forces or touches as one or more inputs, and so on. Various configurations are possible and contemplated without departing from the scope of the present disclosure. 
     Although a number of embodiments are illustrated and discussed above, it is understood that these are examples. Any number of features of these embodiments may be combined into other embodiments without departing from the scope of the present disclosure. Various configurations are possible and contemplated. 
     In various implementations, an electronic device may include a housing; a display coupled to the housing and configured to receive a force, further configured to deform in response to the force; a sense electrode positioned within the housing and capacitively coupled to the display across an air gap defined between the sense electrode and the display; a processing unit operative to estimate an amount of the force based, at least in part, on a change in capacitance between the display and the sense electrode; and a conductive compliant material. The conductive compliant material may be positioned in the housing within the air gap between the display and the sense electrode. 
     In some examples, the display may be operable to contact the conductive compliant material during deformation. In other examples, the display may remain separate from the conductive compliant material during deformation. 
     In a number of examples, the conductive compliant material may be coupled to at least one of the display or the sense electrode. In some examples, the electronic device further includes a midplate coupled to the housing between the sense electrode and the display wherein the conductive compliant material is coupled to the midplate. In various examples, the conductive compliant material may be coupled to the sense electrode by a conductive adhesive. In a number of examples, the electronic device may further include an insulating material coating the conductive compliant material. 
     In some implementations, an electronic device may include a cover; a force sensor that is operable to measure a force exerted on the cover that changes a capacitive gap of the force sensor, the force sensor including a display component coupled to the cover and a sensor assembly coupled to a substrate across an air gap; and a compliant material positioned in the air gap. The compliant material may include a conductive portion, decrease an effective electrical distance of the capacitive gap, and prevent damage to the force sensor by absorbing at least a portion of the force. 
     In various examples, the compliant material may include the conductive portion and a nonconductive portion. In some examples, the compliant material may include a first conductive material connected to a sensing electrode of the force sensor and a second conductive material that functions as a shield electrode. In various such examples, the compliant material may further include insulating material separating the first conductive material and the second conductive material. 
     In some examples, the compliant material may include at least one of a conductive foam, a silicone gasket, an air loop gasket, a fabric, or a conductive adhesive. In a number of examples, the compliant material may be compressible. In various examples, the compliant material may have a thickness of approximately 250-950 microns. 
     In a number of implementations, an electronic device may include a housing; a drive electrode that is operable to deform when a force is exerted; a sense electrode that is operable to detect a change in capacitance when the drive electrode deforms, the sense electrode separated from the drive electrode by a gap; and a conductive compliant material. The conductive compliant material may be positioned in the gap and electrically connected to the sense electrode, the conductive compliant material separated from the drive electrode in the absence of the force and contacted by the drive electrode when the force is exerted. 
     In some examples, the sense electrode may be resistively coupled to the conductive compliant material. In other examples, the sense electrode may be capacitively coupled to the conductive compliant material. 
     In various examples, the electronic device may further include a shield electrode capacitively coupled to the conductive compliant material. In some such examples, the electronic device may further include a nonconductive material separating the shield electrode and the conductive compliant material. In various of such examples, the nonconductive material may separate the sense electrode and the conductive compliant material. 
     As described above and illustrated in the accompanying figures, the present disclosure relates to a compliant material for protecting capacitive force sensors and increasing capacitive sensitivity. A compliant material, such as a conductive foam, may be positioned in the dielectric or capacitive gap between drive and sense electrodes and/or other conductive elements of a capacitive and/or other force sensor, such as a TFT or other display element and a sensor assembly. The compliant material may prevent damage by preventing and/or cushioning contact. The compliant material may be conductive. By being conductive and being positioned between the electrodes while still being separated from one or more of the electrodes, the compliant material may also shorten the effective electrical distance between the electrodes. As a result, the force sensor may be more sensitive than would otherwise be possible while being less vulnerable to damage. 
     In the present disclosure, any methods disclosed may be implemented as sets of instructions or software readable by a device. Further, it is understood that the specific order or hierarchy of steps in the methods disclosed are examples of sample approaches. In other embodiments, the specific order or hierarchy of steps in the method can be rearranged while remaining within the disclosed subject matter. The accompanying method claims present elements of the various steps in a sample order, and are not necessarily meant to be limited to the specific order or hierarchy presented. 
     The described disclosure may utilize a computer program product, or software, that may include a non-transitory machine-readable medium having stored thereon instructions, which may be used to program a computer system (or other electronic devices) to perform a process according to the present disclosure. A non-transitory machine-readable medium includes any mechanism for storing information in a form (e.g., software, processing application) readable by a machine (e.g., a computer). The non-transitory machine-readable medium may take the form of, but is not limited to, a magnetic storage medium (e.g., floppy diskette, video cassette, and so on); optical storage medium (e.g., CD-ROM); magneto-optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM and EEPROM); flash memory; and so on. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20210105
Publication Date: 20220315
Grant Date: 20220315
Priority Date: 20190430
Inventors: BECHSTEIN, DANIEL J.
Petty, Collin R.
GRUNTHANER, MARTIN P.
JOYCE, ANDREW W.
MATTHEWS, JOHN R.
GUPTA, PAVAN O.
LIN, ALBERT
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/0445", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 73016422