PATENT DOCUMENT

Publication Number: US-10416803-B2
Application Number: US-201615272105-A
Country: US
Kind Code: B2

Title: Gasket with embedded capacitive sensor

Abstract:
An electronic device is disclosed. In some examples, the device includes one or more force sensors at its perimeter. The force sensors can be included in a gasket further comprising a rubber-like gasket cover and a compressible dielectric such as air or silicone, for example. A plurality of conductive plates can be embedded in the gasket cover with routing traces coupled thereto to sense a capacitance between the conductive plates. The gasket, including the one or more capacitive sensors, can be disposed between a cover glass and a lower housing of the electronic device. The capacitance of the one or more sensors can change in response to an applied force at the cover glass of the device. The change in capacitance can be sensed via the routing traces to measure the magnitude and, in some examples, location of the applied force.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a lower surface; 
 an upper surface; and 
 a force sensing sealing structure situated between the lower surface and the upper surface, wherein the force sensing sealing structure comprises:
 a flexible cover material formed in a connected circumferential shape, the cover material enclosing a dielectric that is substantially air; 
 a first conductive plate embedded in a first location of the cover material; and 
 a second conductive plate embedded in a second location of the cover material; 
 
 sense circuitry operatively coupled to the first conductive plate, the sense circuitry configured to sense a capacitance between the first conductive plate and the second conductive plate; and 
 a processor configured to determine a magnitude of an applied force at the upper surface of the device based on the sensed capacitance, wherein: 
 a cross-sectional area of the force sensing sealing structure that crosses the force sensing sealing structure at one location around the circumferential shape of the force sensing sealing structure comprises:
 a cross-section of the flexible cover material that encapsulates, in a plane of the cross-sectional area of the force sensing sealing structure, the first conductive plate, the second conductive plate, and the dielectric that is substantially air. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the second location is opposite of the first location; and the first conductive plate and the second conductive plate are horizontal with respect to the force sensing sealing structure. 
     
     
       3. The electronic device of  claim 1 , further comprising:
 drive circuitry coupled to the second conductive plate, the drive circuitry configured to apply a drive signal to the second conductive plate. 
 
     
     
       4. The electronic device of  claim 1 , wherein:
 the first conductive plate and the second conductive plate are spaced a first distance from each other and have a first capacitance in the absence of the applied force; and 
 the first conductive plate and the second conductive plate are spaced a second distance from each other and have a second capacitance in response to the applied force. 
 
     
     
       5. The electronic device of  claim 1 , wherein:
 the first conductive plate is one of a plurality of first conductive plates; 
 the second conductive plate is one of a plurality of second conductive plates; and 
 each first conductive plate corresponds to a second conductive plate as a pair of conductive plates, each pair of conductive plates at a unique location of the force sensing sealing structure. 
 
     
     
       6. The electronic device of  claim 5 , wherein the processor is further configured to:
 sense a capacitance of each pair of conductive plates and determine a location of the applied force based on the sensed capacitances. 
 
     
     
       7. The electronic device of  claim 1 , further comprising a touch screen configured for sensing a location of touch, wherein the processor is further configured to determine a location of the applied force based on the location of touch. 
     
     
       8. The electronic device of  claim 1 , wherein an exterior of the flexible cover material is in direct contact with the lower surface and the upper surface. 
     
     
       9. The electronic device of  claim 1 , wherein the lower surface or the upper surface comprises a channel and the force sensing sealing structure is situated in the channel. 
     
     
       10. The electronic device of  claim 1 , wherein the upper surface comprises a cover material of the device. 
     
     
       11. A force sensing sealing structure comprising:
 a flexible cover material formed in a connected circumferential shape, the cover material enclosing a dielectric that is substantially air; 
 a first conductive plate embedded in a first location of the cover material; and 
 a second conductive plate embedded in a second location of the cover material, wherein: 
 the first conductive plate is operatively coupled to sense circuitry configured to sense a capacitance between the first conductive plate and the second conductive plate, the capacitance indicative of an applied force at the force sensing sealing structure, wherein: 
 a cross-sectional area of the force sensing sealing structure that crosses the force sensing sealing structure at one location around the circumferential shape of the force sensing sealing structure comprises:
 a cross-section of the flexible cover material that encapsulates, in a plane of the cross-sectional area of the force sensing sealing structure, the first conductive plate, the second conductive plate, and the dielectric that is substantially air. 
 
 
     
     
       12. The force sensing sealing structure of  claim 11 , wherein the second location is opposite of the first location. 
     
     
       13. The force sensing sealing structure of  claim 11 , wherein the first conductive plate and the second conductive plate are horizontal with respect to the force sensing sealing structure. 
     
     
       14. The force sensing sealing structure of  claim 11 , wherein the second conductive plate is operatively coupled to drive circuity, the drive circuitry configured to apply a drive signal to the second conductive plate. 
     
     
       15. The force sensing sealing structure of  claim 11 , wherein:
 the first conductive plate and the second conductive plate are spaced a first distance from each other and have a first capacitance in the absence of the applied force; and 
 the first conductive plate and the second conductive plate are spaced a second distance from each other and have a second capacitance in response to the applied force. 
 
     
     
       16. The force sensing sealing structure of  claim 11 , wherein:
 the first conductive plate is one of a plurality of first conductive plates; 
 the second conductive plate is one of a plurality of second conductive plates; and 
 each first conductive plate corresponds to a second conductive plate as a pair of conductive plates, each pair of conductive plates at a unique location of the force sensing sealing structure. 
 
     
     
       17. The force sensing sealing structure of  claim 16 , wherein:
 each first conductive plate is coupled to a first connection of a plurality of first connections, and 
 each second conductive plate is coupled to a second connection of a plurality of second connections.

Description:
FIELD OF THE DISCLOSURE 
     This relates to a capacitive sensor included in an electronic device and, more particularly, to a capacitive sensor embedded in a gasket configured for detecting a force at the electronic device. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch electrode panels, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch electrode panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch electrode panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch and the position of the touch on the touch electrode panel, and the computing system can then interpret the touch in accordance with the display appearing at the time of the touch, and thereafter can perform one or more actions based on the touch. In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing electrical fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface. 
     In some examples, touch panels/touch screens may include force sensing capabilities—that is, they may be able to detect an amount of force with which an object is touching the touch panels/touch screens. These forces can constitute force inputs to electronic devices for performing various functions, for example. In some examples, an electronic device can include one or more force sensors around the perimeter of a touch screen. 
     SUMMARY 
     The present disclosure relates to a dielectric-filled gasket with a capacitive sensor. In some examples, the gasket can be included in an electronic device further comprising a cover glass and a lower housing. The cover glass can be attached to the lower housing via a clamp mechanism, for example. In some examples, the lower housing can include a groove around its interior perimeter in which the gasket can sit, forming a seal. The gasket can include one or more pairs of parallel conductive plates encased in a rubber-like material, the rubber-like material surrounding a dielectric such as air or silicone, for example. In some examples, the gasket can further include routing traces coupled to the parallel conductive plates to sense a change in capacitance caused by a force applied to the cover glass of the device. A pair of conductive plates can be used to determine a magnitude of an applied force, for example. In some examples, the gasket can include multiple pairs of parallel conductive plates so as to determine a location of an applied force in addition to its magnitude (e.g., one sensor pair corresponding to each corner of a device). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate exemplary devices that can include one or more force sensors according to examples of the disclosure. 
         FIG. 2A  illustrates a top view of an exemplary device including a force sensor at its perimeter according to examples of the disclosure. 
         FIG. 2B  illustrates a cross-section of a device including a force sensor according to examples of the disclosure. 
         FIG. 3A  illustrates a top view of an exemplary device including a plurality force sensors, each including conductive plates, at its perimeter according to examples of the disclosure. 
         FIG. 3B  illustrates a cross-section of a device including a force sensor according to examples of the disclosure. 
         FIG. 4A  illustrates a top view of an exemplary device including a force sensor at its perimeter according to examples of the disclosure. 
         FIGS. 4B-4C  illustrate cross-sectional views of an exemplary device including a force sensor according to examples of the disclosure. 
         FIG. 5  illustrates an exemplary method for measuring an applied force at an electronic device according to examples of the disclosure. 
         FIG. 6  illustrates exemplary computing system capable of implementing force sensing according to examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples. 
     The present disclosure relates to a dielectric-filled gasket with a capacitive sensor. In some examples, the gasket can be included in an electronic device further comprising a cover glass and a lower housing. The cover glass can be attached to the lower housing via a clamp mechanism, for example. In some examples, the lower housing can include a groove around its interior perimeter in which the gasket can sit, forming a seal. The gasket can include one or more pairs of parallel conductive plates encased in a rubber-like material, the rubber-like material surrounding a dielectric such as air or silicone, for example. In some examples, the gasket can further include routing traces coupled to the parallel conductive plates to sense a change in capacitance caused by a force applied to the cover glass of the device. A pair of conductive plates can be used to determine a magnitude of an applied force, for example. In some examples, the gasket can include multiple pairs of parallel conductive plates so as to determine a location of an applied force in addition to its magnitude (e.g., one sensor pair corresponding to each corner of a device). 
       FIGS. 1A-1C  illustrate exemplary devices that can include one or more force sensors according to examples of the disclosure.  FIG. 1A  illustrates an example mobile telephone  136  that includes a touch screen  124 .  FIG. 1B  illustrates an example digital media player  140  that includes a touch screen  126 .  FIG. 1C  illustrates an example watch  144  that includes a touch screen  128 . It is understood that the above touch screens can be implemented in other devices as well, such as tablet computers or other wearable devices. Further, though the examples of the disclosure are provided in the context of a touch screen, it is understood that the examples of the disclosure can similarly be implemented in a touch sensor panel without display functionality. 
     In some examples, touch screens  124 ,  126  and  128  can be based on self-capacitance. A self-capacitance based touch system can include a matrix of small, individual plates of conductive material that can be referred to as touch node electrodes. For example, a touch screen can include a plurality of individual touch node electrodes, each touch node electrode identifying or representing a unique location on the touch screen at which touch or proximity (i.e., a touch or proximity event) is to be sensed, and each touch node electrode being electrically isolated from the other touch node electrodes in the touch screen. Such a touch screen can be referred to as a pixelated self-capacitance touch screen, though it is understood that in some examples, the touch node electrodes on the touch screen can be used to perform scans other than self-capacitance scans on the touch screen (e.g., mutual capacitance scans). During operation, a touch node electrode can be stimulated with an AC waveform, and the self-capacitance to ground of the touch node electrode can be measured. As an object approaches the touch node electrode, the self-capacitance to ground of the touch node electrode can change. This change in the self-capacitance of the touch node electrode can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. In some examples, the electrodes of a self-capacitance based touch system can be formed from rows and columns of conductive material, and changes in the self-capacitance to ground of the rows and columns can be detected, similar to above. In some examples, a touch screen can be multi-touch, single touch, projection scan, full-imaging multi-touch, capacitive touch, etc. 
     In some examples, touch screens  124 ,  126  and  128  can be based on mutual capacitance. A mutual capacitance based touch system can include drive and sense lines that may cross over each other on different layers, or may be adjacent to each other on the same layer. The crossing or adjacent locations can be referred to as touch nodes. During operation, the drive line can be stimulated with an AC waveform and the mutual capacitance of the touch node can be measured. As an object approaches the touch node, the mutual capacitance of the touch node can change. This change in the mutual capacitance of the touch node can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. 
     In some examples, a device of the disclosure can include force sensing capability in addition to the touch sensing capability discussed above. In the context of this disclosure, touch sensing can refer to the touch screen&#39;s ability to determine the existence and/or location of an object touching the touch screen, and force sensing can refer to the touch screen&#39;s ability to determine a “depth” of the touch on the touch screen (e.g., the degree of force with which the object is touching the touch screen). In some examples, the touch screen can also determine a location of the force on the touch screen. 
       FIG. 2A  illustrates a top view of an exemplary device  200  including a force sensor  210  at its perimeter according to examples of the disclosure. In some examples, the force sensor  210  can be one continuous sensor around the perimeter of the device  200 . The force sensor  210  can include a connection  212  that can be operatively coupled to a processor (not shown) of the device  200 , for example. In some examples, the force sensor  210  can include multiple force sensors electrically isolated from each other, wherein each force sensor has a connection operatively coupled to the processor. A cross-section of device  200  is illustrated in  FIG. 2B . 
       FIG. 2B  illustrates a cross-section of a device  200  including a force sensor  210  according to examples of the disclosure. In some examples, the device  200  can include a cover glass  250  (which can alternatively made of other materials such as plastic), a device housing  260 , and a force sensor  210  disposed therebetween. The force sensor  210  can include pressure-sensitive adhesive (PSA)  214 , conductive plates  216 , connections  212 , and a compressible dielectric  218 . In some examples, the conductive plates  216  can be disposed at a distance d 1  from one another and each can be coupled to a connection  212 . Conductive plates  216  can be situated normal to an applied force at the cover glass  250  of device  200 . Additionally or alternatively, in some examples, conductive plates  216  can be situated in a different orientation to sense an applied force at a different location (e.g. a force applied at the edges of device  200 ). 
     In some examples, conductive plates  216  can function as a parallel-plate capacitor. When no force is applied to the cover glass  250  of the device  200 , the conductive plates can be a nominal distance d 1  from each other. When a force is applied to cover glass  250 , the distance d 1  between the conductive plates  216  can change. In some examples, a change in distance d 1  between the conductive plates  216  can cause the capacitance of the plates to change. The capacitance of the conductive plates  216  can be measured via connections  212 , for example. In some examples, the capacitance can be measured by applying a first signal (e.g., an AC signal) to one of the conductive plates  214  and measuring a second signal at the other conductive plate. In some examples, the PSA  214  and compressible dielectric  218  can be made of compressible materials that yield under an applied force, allowing for distance d 1  to change in response to an applied force. Therefore, by sampling, via connections  212 , the capacitance of pressure sensor  210 , a magnitude of force at the cover glass  250  can be determined. 
     In some examples, a location of an applied force can be determined based on touch data provided by a touch sensor, such as a touch screen (e.g., touch screen  124 ,  126 , or  128 ) further included in device  200 . In some examples, multiple force sensors  210  can be included along the perimeter of device  200 . By determining the magnitude of force sensed by each of a plurality of force sensors, a centroid of one or more applied forces can be determined. 
     In some examples, the cover glass  250  and device housing  260  can be held together by PSA  214  included in the force sensor  210 . By including a force sensor  210  around the perimeter of device  200 , the PSA  214  can protect the internal electronics (not shown) of the device from liquids and particles outside of the device. 
     Although the exemplary force sensor  210  described with reference to  FIGS. 2A-2B  can measure force and provide PSA  214  to hold device  200  together, over time, the PSA can weaken from exposure to chemicals and/or sheer forces. Eventually, device  200  can lose its waterproof properties or cover glass  250  can be come displaced as PSA  214  weakens. Further, to access the internal electronics (not shown) of device  200  for troubleshooting or maintenance purposes, the cover glass  250  must be removed, which can destroy the pressure sensor  210 . Therefore, installation of a new pressure sensor can be required in addition to any other maintenance to be performed on the device. Therefore, in some examples, it can be advantageous to hold the device  200  together without the use of PSA and include a pressure sensor that can function as a gasket to seal the inside of the device. 
       FIG. 3A  illustrates a top view of an exemplary device  300  including a plurality force sensors, each including conductive plates  316 , at its perimeter according to examples of the disclosure. In some examples, the conductive plates  316  can be included in a gasket, which can further include gasket cover  314 , disposed along the perimeter of the device  300 . Gasket cover  314  can be made of a flexible and/or compressible material, such as rubber or plastic, for example. In some examples, each conductive plate  316  can be coupled to a connection  312  that can be further operatively coupled to a processor of the device  300 . The gasket including the conductive plates  316  can seal the perimeter of the device  300 , for example. In some examples, the conductive plates  314  can be electrically isolated from one another by gaps  311 . The gaps  311  can be filled with the gasket cover  314  material, thereby forming a complete gasket around the perimeter of the device  300 . Therefore, in some examples, the gasket can be rectangle-shaped to conform to the shape of the device  300 . Other shapes, such as circles, ovals, or squares, for example, are possible. In some examples, a different material can be used to fill gaps  311 . Alternatively, in some examples, the device  300  can include one force sensor along its full perimeter. Device  300  can further include a channel  362  to hold the gasket including the conductive plates  316  in place, for example. In some examples, the channel  362  can include gaps  364  to allow the connections  312  to be coupled to internal electronics of the device  300 . Although  FIG. 3A  illustrates the conductive plates  316  as being placed at the corners of device  300 , in some examples, different placement of the conductive plates  316  is possible. Furthermore, although device  300  can have four pairs of conductive plates  316 ; other numbers of conductive plates are possible. A cross-section of device  300  is illustrated in  FIG. 3B . 
       FIG. 3B  illustrates a cross-section of a device  300  including a force sensor  310  according to examples of the disclosure. In some examples, force sensor  310  can be one of a plurality of force sensors included in device  300 . The device  300  can include a cover glass  350  (or other cover material), a device housing  360 , and a force sensor  310  disposed therebetween, for example. The device  300  can be held together by clamp  370 , which can apply a nominal compressive force represented by spring  372 . Clamp  370  can include a spring like mechanism other than spring  372  in some examples. The force sensor  310  can include gasket cover  314  (e.g., a rubber-like insulative coating), conductive plates  316 , connections  312 , and a compressible dielectric  318 . In some examples, the conductive plates  316  can be disposed at a distance d 2  from one another and each be coupled to a connection  312 . Conductive plates  316  can be situated normal to an applied force at the cover glass  350  of device  300 . Additionally or alternatively, in some examples, conductive plates  316  can be situated in a different orientation to sense an applied force at a different location (e.g. a force applied at the edges of device  300 ). 
     In some examples, the gasket including the force sensors  310  can be manufactured using an over-molding technique. One or more sensors  310  including conductive plates  316 , compressible dielectric  318 , and connections  312  can be provided. The one or more sensors  310  can be arranged in a shape of the perimeter of device  300 , and the gasket cover  314  can be over-molded to cover the one or more sensors. In some examples, the gasket can include a single force sensor  310  formed in the shape of the perimeter of device  300 . Over-molding can include providing sensors  310  in a mold having the shape of the gasket and filling the mold with the gasket cover  314  material, thus applying the gasket cover around the sensors, for example. Additionally or alternatively, the gasket cover  314  material can be applied to the arranged sensors  310  with a different technique, such as dipping the sensors in the gasket cover material or brushing or spraying the gasket material onto the sensors. Once formed, the gasket can be inserted into the channel  362  of the device housing  360  and the rest of the device  300  can be assembled. In some examples, the resulting cross-section of the gasket can have an oval shape. Depending on how the gasket cover material is applied, other cross-sectional shapes, such as circles, squares, or rectangles, for example, are possible. 
     Once the device  300  is assembled with the force sensors  310  in the correct position, conductive plates  316  can function as a parallel-plate capacitor. When no force is applied to the cover glass  350  of the device  300 , the conductive plates can be a nominal distance d 2  from each other. A capacitance of the conductive plates  316  can be measured via connections  312 . In some examples, a capacitance can be measured by applying a first signal to one of the conductive plates  316  and measuring a second signal at the other conductive plate. In some examples, the gasket cover  314  and compressible dielectric  318  can be made of compressible materials that yield under an applied force. The gasket cover  314  and compressible dielectric  318  can be made of a same material or of different materials. When a force is applied to cover glass  350 , the distance d 2  between the conductive plates  316  can change. In some examples, a change in distance d 2  between the conductive plates  316  can cause the capacitance of the plates to change. Therefore, by sampling the capacitance of pressure sensor  310  via connections  312 , a magnitude of force at the cover glass  350  can be determined. In some examples, it can be advantageous to include a flexible, but not compressible gasket cover  314  and a compressible dielectric  318  to increase a change in distance d 2  between conductive plates  316  in response to an applied force. 
     In some examples, a location of one or more applied forces can be determined based on the relative forces measured at each of the plurality of force sensors  310 . Additionally or alternatively, touch data provided by a touch sensor, such as a touch screen (e.g., touch screen  124 ,  126 , or  128 ) further included in device  300  can be used to determine the location of the one or more applied forces. 
     In some examples, the cover glass  350  and device housing  360  can be held together by clamp  370 . Clamp  370  can include a spring  372  (or other similar mechanism) to apply a nominal compressive force between the cover glass  350  and the device housing  360 . It should be understood that clamp  370  is exemplary and other coupling means may be used. For example, a clamp can be interior to the device and/or may include a different mechanism to apply a nominal compressive force to join cover glass  350  and device housing  360 . Spring  372  and compressible dielectric  318  can be selected such that the nominal force required to hold device  300  together can be overcome by a force applied by a user of the device. When selecting compressible dielectric  318 , a tradeoff can be made between providing a low nominal force and increased responsiveness with a soft dielectric versus increased durability with a firm dielectric. Because clamp  370  can apply a nominal force, a minimum measurable force can be limited by the clamp. That is, forces that are a lower magnitude than the nominal force may not be sensed. In some examples, a maximum measurable force can be limited by a height of channel  362 . This maximum measurable force can simplify calibration by providing an upper limit on a measurable applied force. Further, channel  362  can limit the displacement of cover glass  350 , protecting the internal electronics of device  300 . Channel  362  can hold the gasket including the sensor  310  in place. By including the gasket, including sensors  310 , around the full perimeter of device  300 , the gasket can provide a seal to protect the internal electronics (not shown) of the device from liquids and particles outside of the device. 
     By providing the clamp  370  to hold device  300  together and the gasket including pressure sensors  310  as a seal, the device can have increased durability compared to a device (e.g., device  200 ) held together by PSA (e.g., PSA  214 ). For example, device  300  can be chemically resistant. Furthermore, the pressure sensors  310  can be reused if cover glass  350  is removed to perform troubleshooting or maintenance on the internal electronics of the device  300 . To access the internal electronics of the device  300 , clamp  370  and cover glass  350  can be removed. To reassemble the device, clamp  370  and cover glass  350  can be reassembled without damaging sensor  310 . In some examples, after reassembly, sensor  310  can be recalibrated to account for any change in the nominal force applied by the clamp  370 . 
       FIG. 4A  illustrates a top view of an exemplary device  400  including a force sensor  410  at its perimeter according to examples of the disclosure. In some examples, the force sensor  410  can be disposed along the perimeter of the device  400 . The force sensor  410  can include a connection  412  that can be operatively coupled to a processor of the device  400 , for example. The force sensor  410  can function as a gasket to seal the perimeter of the device  400 , for example. Therefore, in some examples, the gasket can be rectangle-shaped to conform to the shape of the device  400 . In some examples, other shapes, such as squares, circles, or ovals, for examples, are possible. Device  400  can further include a channel  462  to hold the gasket including the pressure sensor  410  in place, for example. In some examples, the channel  462  can include a gap  464  to allow the connection  412  to be coupled to internal electronics of the device  300 . Although device  400  is shown as including a single force sensor  410  along its perimeter, in some examples, multiple electrically isolated force sensors, each with connections couplable to a processor, are possible. Cross-sectional views of device  400  are illustrated in  FIGS. 4B-4C . 
       FIGS. 4B-4C  illustrate cross-sectional views of an exemplary device  400  including a force sensor  410  according to examples of the disclosure. In some examples, force sensor  410  can be one of a plurality of force sensors included in device  400 . The device  400  can include a cover glass  450  (or other cover material), a device housing  460 , and a force sensor  410  disposed therebetween, for example. The device  400  can be held together by a clamp  470  configured to apply a nominal compressive force to the device. In some examples, this compressive force can be modeled by a spring  472 . The force sensor  410  can include gasket cover  414 , conductive plates  416 , connections  412 , and a compressible dielectric  418 . The compressible dielectric  418  can be non-structural, for example. In some examples, air can be used as the compressible dielectric  418 , thus allowing for a hollow gasket. Conductive plates  416  can be situated normal to an applied force at the cover glass  450  of device  400 . Additionally or alternatively, in some examples, conductive plates  416  can be situated in a different orientation to sense an applied force at a different location (e.g. a force applied at the edges of device  400 ). 
     In some examples, the gasket can be manufactured using an extrusion technique. One or more extrusion molds can be provided to shape the conductive plates  416 , flexible dielectric  418 , and gasket cover  414  into an elongated shape with a desired cross-sectional structure. Although the cross section of the gasket illustrated in  FIG. 4B  can be oval-shaped, other cross-sectional shapes, such as squares, rectangles, or circles, for example, are possible, depending on the shape of the extrusion molds used. The resulting elongated capacitor can be shaped to fit the perimeter of device  400 , thus forming the gasket including the pressure sensor  410 , as described above. Extrusion molding can allow the gasket to be formed using a non-structural dielectric, for example. For example, extrusion molding can be used to form a hollow gasket, allowing air to function as the compressible dielectric  418 . Once formed, the gasket can be inserted into the channel  462  of the device housing  460  and the rest of the device  400  can be assembled. 
     Once the device  400  is assembled, including the pressure sensor  410 , conductive plates  416  can function as a parallel-plate capacitor. The conductive plates  416  can be disposed such that, when no force is present, their centers are a distance d 3  from each other and their edges are a distance d 4  from each other, due to their curvature, as shown in  FIG. 4B . In the presence of a force F, the conductive plates can move closer together and their curvature can decrease. For example, the centers of the conductive plates  416  can be a distance d 5  from each other and the edges can be a distance d 6  from each other, as shown in  FIG. 4C . In some examples, these changes in distance between the conductive plates  416  can cause a capacitance of the plates to change. The capacitance of the conductive plates  416  can be measured via connections  412 , for example. In some examples, a capacitance can be measured by applying a first signal to one of the conductive plates  416  and measuring a second signal at the other conductive plate. In some examples, the gasket cover  414  and compressible dielectric  418  can be made of compressible materials that yield under an applied force. In some examples, air can be used as the compressible dielectric  418 , allowing the gasket to be hollow. Therefore, by sampling the capacitance of pressure sensor  410  via connections  412 , a magnitude of force at the cover glass  450  can be determined. 
     In some examples, a location of one or more applied forces can be determined based on touch data provided by a touch sensor, such as a touch screen (e.g., touch screen  124 ,  126  or  128 ) further included in device  400 . That is, it can be assumed that a centroid of touch is also a centroid of an applied force, for example. In some examples including multiple pressure sensors, the relative forces measured at each of the plurality of force sensors can be weighed to determine force location in addition to or as an alternative to using touch data to determine force location. 
     In some examples, the cover glass  450  and device housing  360  can be held together by a clamp  470 . Clamp  470  can include a spring  472  (or similar mechanism) to apply a nominal compressive force between the cover glass  450  and the device housing  460 . It should be understood that clamp  470  is exemplary and other coupling means may be used. For example, a clamp or other coupling means can be interior to the device and/or may include a different mechanism to apply a nominal compressive force to join cover glass  450  and device housing  460 . Spring  472  and compressible dielectric  418  can be selected such that the nominal force required to hold device  400  together can be readily overcome by a force applied by a user of the device. When selecting compressible dielectric  418 , a tradeoff can be made between providing a low nominal force and increased responsiveness by using a soft dielectric versus increased durability provided by using a firm dielectric. In some examples, it can be advantageous to use air or another non-structural dielectric material as the compressible dielectric  418  because it is both soft and robust. For example, air can be repeatedly compressed by applied forces over time without deforming or otherwise deteriorating. Because clamp  470  can apply a nominal compressive force, a minimum detectable force can be set by the clamp. That is, an applied force with a magnitude less than the nominal compressive force may not be sensed. In some examples, a maximum measurable force can be limited by a height of channel  462 . This maximum measurable force can simplify calibration by providing an upper limit on a measurable applied force. Further, channel  462  can limit the displacement of cover glass  450 , protecting the internal electronics of device  400 . Channel  462  can hold the gasket including the sensor  410  in place. By including the gasket around the full perimeter of device  400 , the gasket can provide a seal to protect the internal electronics (not shown) of the device from liquids and particles outside of the device. 
     By providing the clamp  470  to hold device  400  together and the gasket including pressure sensors  410  as a seal, the device can have increased durability compared to a device (e.g., device  200 ) held together by PSA (e.g., PSA  214 ). For example, device  400  can be chemically resistant. Furthermore, the pressure sensors  410  can be reused if cover glass  450  is removed to perform maintenance or troubleshooting on the internal electronics of the device  400 . To access the internal electronics of the device  400 , clamp  470  and cover glass  450  can be removed. To re-assemble the device, clamp  470  and cover glass  450  can be re-assembled without damaging sensor  410 . In some examples, after re-assembly, sensor  410  can be recalibrated to account for any change in nominal force applied by clamp  470 . Further, in some examples, air or a different non-structural dialectic material can be used as compressible dielectric  418 . In some examples, air can be both soft and robust, allowing for a low nominal force, relatively increased force sensor  410  responsiveness, and sensor durability, as described above. 
       FIG. 5  illustrates an exemplary method  500  for measuring an applied force at an electronic device according to examples of the disclosure. Method  500  can be performed by an electronic device according to the exampled described above with reference to  FIGS. 1-4 . 
     In some examples, the method  500  can include calibrating  502  the one or more force sensors (e.g., force sensors  210 ,  310  or  410 ) included in the electronic device. Calibration can be performed at the manufacturing facility and/or using specialized equipment. For example, a series of forces of known magnitudes and locations can be applied to the electronic device. The corresponding capacitive response of the one or more force sensors can be measured and associated with the known applied force to create a model of the one or more force sensors. The model can be a lookup table (LUT) or a function, for example, and can be stored in a memory of the electronic device. 
     While the device is operating, the one or more force sensors (e.g., force sensors  210 ,  310  or  410 ) can be measured  504 . In some examples, measuring a force sensor can include measuring a capacitance of a force sensor including conductive plates (e.g., conductive plates  216 ,  316  or  416 ). For example, the one or more force sensors can include two conductive plates, forming a parallel plate capacitor. To measure the capacitance of a force sensor including a parallel plate capacitor, a first conductive plate can receive a first signal and a second signal of a second plate can be measured (e.g., via connections  212 ,  312  or  412 ). The capacitance can be determined based on the measured signal of the second plate. In some examples, the one or more sensors can have a different number of conductive plates. Other types of force sensors are possible. 
     In some examples, a magnitude of an applied force can be determined  506  based on the measurement of the force sensor. In some examples, determining the magnitude of the applied force can include applying a model (e.g., a LUT or a function) to the one or more measured force sensors. The model can be obtained during a calibration procedure, such as calibration  502 , for example. In some examples, determining a magnitude of force can include combining the measurements from a plurality of force sensors included in a device (e.g., plurality of force sensors  310  included in device  300 ). 
     In some examples, a location of force can also be determined  508 . Determining a location of force can occur before, after, or at a same time as determining a magnitude of applied force. In some examples, determining a location of force can include weighing the measurements of a plurality of force sensors (e.g., plurality of force sensors  310 ), each at a unique location on the electronic device. Additionally or alternatively, determining a location of force can include analyzing touch data from a touch sensor further included in the electronic device. For example, in a device including only one force sensor (e.g., device  200  or  400 , having sensor  210  or  410 , respectively), the location of force can be a location of an object touching the touch screen of a device. In some examples, touch data can be used in conjunction with force data from a plurality of force sensors for a more accurate determination of a force location. 
     In response to a detected force, the electronic device can perform  510  an associated action. For example, the applied force can be user input for a secondary touch action (e.g., right click). In some examples, an action to be performed in response to an applied force can vary depending on which application is running on the electronic device. An applied force can be processed as user input along with other input modalities such as touch screen input, keyboard input, and/or voice control, to name a few examples. 
       FIG. 6  illustrates exemplary computing system  600  capable of implementing force sensing according to examples of the disclosure. Computing system  600  can include a touch sensor panel  602  to detect touch or proximity (e.g., hover) events from a finger  606  or stylus  608  at a device, such as a mobile phone, tablet, touchpad, portable or desktop computer, portable media player, wearable device or the like. Touch sensor panel  602  can include a pattern of electrodes to implement various touch and/or stylus sensing scans. The pattern of electrodes can be formed of a transparent conductive medium such as Indium Tin Oxide (ITO) or Antimony Tin Oxide (ATO), although other transparent and non-transparent materials, such as copper, can also be used. For example, the touch sensor panel  602  can include an array of touch nodes that can be formed by a two-layer electrode structure (e.g., row and column electrodes) separated by a dielectric material, although in other examples the electrodes can be formed on the same layer. Touch sensor panel  602  can be based on self-capacitance or mutual capacitance or both, as previously described. 
     In addition to touch sensor panel  602 , computing system  600  can include display  604  and force sensor circuitry  610  (e.g., including force sensor  210 ,  310  or  410 ) to create a touch and force sensitive display screen. Display  604  can use liquid crystal display (LCD) technology, light emitting polymer display (LPD) technology, organic LED (OLED) technology, or organic electro luminescence (OEL) technology, although other display technologies can be used in other examples. In some examples, the touch sensor panel  602 , display  604  and/or force sensor circuitry  610  can be stacked on top of one another. For example, touch sensor panel  602  can cover a portion or substantially all of a surface of display  604 . In other examples, the touch sensor panel  602 , display  604  and/or force sensor circuitry  610  can be partially or wholly integrated with one another (e.g., share electronic components, such as in an in-cell touch screen). 
     Computing system  600  can include one or more processors, which can execute software or firmware implementing and synchronizing display functions and various touch, stylus and/or force sensing functions according to examples of the disclosure. The one or more processors can include a touch processor in touch controller  612 , a force processor in force controller  614  and a host processor  616 . Force controller  614  can implement force sensing operations, for example, by controlling force sensor circuitry  610  (e.g., stimulating one or more electrodes of the force sensor circuitry  610 ) and receiving force sensing data (e.g., mutual capacitance information) from the force sensor circuitry  610  (e.g., from one or more electrodes mounted on a flex circuit). In some examples, the force controller  614  can implement the force sensing, error metric tracking and/or coefficient learning processes of the disclosure. In some examples, the force controller  614  can be coupled to the touch controller  612  (e.g., via an I2C bus) such that the touch controller can configure the force controller  614  and receive the force information from the force controller  614 . The force controller  614  can include the force processor and can also include other peripherals (not shown) such as random access memory (RAM) or other types of memory or storage. In some examples, the force controller  614  can be implemented as a single application specific integrated circuit (ASIC) including the force processor and peripherals, though in other examples, the force controller can be divided into separate circuits. 
     Touch controller  612  can include the touch processor and can also include peripherals (not shown) such as random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Additionally, touch controller  612  can include circuitry to drive (e.g., analog or digital scan logic) and sense (e.g., sense channels) the touch sensor panel  602 , which in some examples can be configurable based on the scan event to be executed (e.g., mutual capacitance row-column scan, row self-capacitance scan, stylus scan, pixelated self-capacitance scan, etc.). The touch controller  612  can also include one or more scan plans (e.g., stored in memory) that can define a sequence of scan events to be performed at the touch sensor panel  602 . In one example, during a mutual capacitance scan, drive circuitry can be coupled to each of the drive lines on the touch sensor panel  602  to stimulate the drive lines, and the sense circuitry can be coupled to each of the sense lines on the touch sensor panel to detect changes in capacitance at the touch nodes. The drive circuitry can be configured to generate stimulation signals to stimulate the touch sensor panel one drive line at a time, or to generate multiple stimulation signals at various frequencies, amplitudes and/or phases that can be simultaneously applied to drive lines of touch sensor panel  602  (i.e., multi-stimulation scanning). In some examples, the touch controller  612  can be implemented as a single application specific integrated circuit (ASIC) including the touch processor, drive and sense circuitry, and peripherals, though in other examples, the touch controller can be divided into separate circuits. The touch controller  612  can also include a spectral analyzer to determine low noise frequencies for touch and stylus scanning. The spectral analyzer can perform spectral analysis on the scan results from an unstimulated touch sensor panel  602 . 
     Host processor  616  can receive outputs (e.g., touch information) from touch controller  612  and can perform actions based on the outputs that can include, but are not limited to, moving one or more objects such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or a document, viewing a menu, making a selection, executing instructions, operating a peripheral device coupled to the host device, answering a telephone call, placing a telephone call, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, or the like. Host processor  616  can receive outputs (e.g., force information) from force controller  614  and can perform actions based on the outputs that can include previewing the content of a user interface element on which the force has been provided, providing shortcuts into a user interface element on which the force has been provided, or the like. Host processor  616  can execute software or firmware implementing and synchronizing display functions and various touch, stylus and/or force sensing functions. Host processor  616  can also perform additional functions that may not be related to touch sensor panel processing, and can be coupled to program storage and display  604  for providing a user interface (UI) to a user of the device. Display  604  together with touch sensor panel  602 , when located partially or entirely under the touch sensor panel  602 , can form a touch screen. The computing system  600  can process the outputs from the touch sensor panel  602  to perform actions based on detected touch or hover events and the displayed graphical user interface on the touch screen. 
     Computing system  600  can also include a display controller  618 . The display controller  618  can include hardware to process one or more still images and/or one or more video sequences for display on display  604 . The display controller  618  can be configured to generate read memory operations to read the data representing the frame/video sequence from a memory (not shown) through a memory controller (not shown), for example. The display controller  618  can be configured to perform various processing on the image data (e.g., still images, video sequences, etc.). In some examples, the display controller  618  can be configured to scale still images and to dither, scale and/or perform color space conversion on the frames of a video sequence. The display controller  618  can be configured to blend the still image frames and the video sequence frames to produce output frames for display. The display controller  618  can also be more generally referred to as a display pipe, display control unit, or display pipeline. The display control unit can be generally any hardware and/or firmware configured to prepare a frame for display from one or more sources (e.g., still images and/or video sequences). More particularly, the display controller  618  can be configured to retrieve source frames from one or more source buffers stored in memory, composite frames from the source buffers, and display the resulting frames on the display  604 . Accordingly, display controller  618  can be configured to read one or more source buffers and composite the image data to generate the output frame. 
     In some examples, the display controller and host processor can be integrated into an ASIC, though in other examples, the host processor  616  and display controller  618  can be separate circuits coupled together. The display controller  618  can provide various control and data signals to the display, including timing signals (e.g., one or more clock signals) and/or vertical blanking period and horizontal blanking interval controls. The timing signals can include a pixel clock that can indicate transmission of a pixel. The data signals can include color signals (e.g., red, green, blue). The display controller  618  can control the display  604  in real-time, providing the data indicating the pixels to be displayed as the display is displaying the image indicated by the frame. The interface to such a display  604  can be, for example, a video graphics array (VGA) interface, a high definition multimedia interface (HDMI), a digital video interface (DVI), a LCD interface, a plasma interface, or any other suitable interface. 
     Note that one or more of the functions described above can be performed by firmware stored in memory and executed by the touch processor in touch controller  612 , or stored in program storage and executed by host processor  616 . The firmware can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer-readable storage medium” can be any medium (excluding a signal) that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer readable medium storage can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
     It is to be understood that the computing system  600  is not limited to the components and configuration of  FIG. 6 , but can include other or additional components in multiple configurations according to various examples. Additionally, the components of computing system  600  can be included within a single device, or can be distributed between multiple devices. 
     Therefore, according to the above, some examples of the disclosure are directed to an electronic device comprising: a lower surface; an upper surface; and a force sensing sealing structure situated between the lower surface and the upper surface, wherein the force sensing sealing structure comprises: a flexible cover material formed in a connected circumferential shape, the cover material enclosing a dielectric; a first conductive plate embedded in a first location of the cover material; and a second conductive plate embedded in a second location of the cover material; sense circuitry operatively coupled to the first conductive plate, the sense circuitry configured to sense a capacitance between the first conductive plate and the second conductive plate; and a processor configured to determine a magnitude of an applied force at the upper surface of the device based on the sensed capacitance. Additionally or alternatively, in some examples the second location is opposite of the first location; and the first conductive plate and the second conductive plate are horizontal with respect to the force sensing sealing structure. Additionally or alternatively, in some examples, the electronic device further comprises drive circuitry coupled to the second conductive plate, the drive circuitry configured to apply a drive signal to the second conductive plate. Additionally or alternatively, in some examples the first conductive plate and the second conductive plate are spaced a first distance from each other and have a first capacitance in the absence of the applied force; and the first conductive plate and the second conductive plate are spaced a second distance from each other and have a second capacitance in response to the applied force. Additionally or alternatively, in some examples the first conductive plate is one of a plurality of first conductive plates; the second conductive plate is one of a plurality of second conductive plates; and each first conductive plate corresponds to a second conductive plate as a pair of conductive plates, each pair of conductive plates at a unique location of the force sensing sealing structure. Additionally or alternatively, in some examples the processor is further configured to: sense a capacitance of each pair of conductive plates and determine a location of the applied force based on the sensed capacitances. Additionally or alternatively, in some examples the electronic device further comprises a touch screen configured for sensing a location of touch, wherein the processor is further configured to determine a location of the applied force based on the location of touch. Additionally or alternatively, in some examples an exterior of the flexible cover material is in direct contact with the lower surface and the upper surface. Additionally or alternatively, in some examples the lower surface or the upper surface comprises a channel and the force sensing sealing structure is situated in the channel. Additionally or alternatively, in some examples the upper surface comprises a cover material of the device. 
     Some examples of the disclosure relate to a force sensing sealing structure comprising: a flexible cover material formed in a connected circumferential shape, the cover material enclosing a dielectric; a first conductive plate embedded in a first location of the cover material; and a second conductive plate embedded in a second location of the cover material, wherein: the first conductive plate is operatively coupled to sense circuitry configured to sense a capacitance between the first conductive plate and the second conductive plate, the capacitance indicative of an applied force at the force sensing sealing structure. Additionally or alternatively, in some examples the dielectric is a non-structural compressible dielectric. Additionally or alternatively, in some examples the dielectric is air or silicone. Additionally or alternatively, in some examples the second location is opposite of the first location. Additionally or alternatively, in some examples the first conductive plate and the second conductive plate are horizontal with respect to the force sensing sealing structure. Additionally or alternatively, in some examples the second conductive plate is operatively coupled to drive circuity, the drive circuitry configured to apply a drive signal to the second conductive plate. Additionally or alternatively, in some examples the first conductive plate and the second conductive plate are spaced a first distance from each other and have a first capacitance in the absence of the applied force; and the first conductive plate and the second conductive plate are spaced a second distance from each other and have a second capacitance in response to the applied force. Additionally or alternatively, in some examples the first conductive plate is one of a plurality of first conductive plates; the second conductive plate is one of a plurality of second conductive plates; and each first conductive plate corresponds to a second conductive plate as a pair of conductive plates, each pair of conductive plates at a unique location of the force sensing sealing structure. Additionally or alternatively, in some examples the first connection is one of a plurality of first connections; the second connection is one of a plurality of second connections; each first conductive plate is coupled to a first connection of the plurality of first connections; each second conductive plate is coupled to a second connection of the plurality of second connections. 
     Some examples of the disclosure relate to an electronic device comprising: a lower surface; an upper surface; and a force sensing sealing structure comprising: means for compressing under an applied force at the upper surface; and means for sensing a capacitance of the force sensing sealing structure, the capacitance indicative of the applied force at the upper surface, wherein the force sensing sealing structure is situated between the first surface and the second surface. 
     Although examples of this disclosure have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of examples of this disclosure as defined by the appended claims.

Metadata:
Filing Date: 20160921
Publication Date: 20190917
Grant Date: 20190917
Priority Date: 20160921
Inventors: SHUMA, Richard D.
CARNOHAN, KRISTEN
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/169", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04142", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/169", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01L1/142", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04142", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/169", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01L1/142", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01L1/142", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61620331