Force Determination Employing Sheet Sensor and Capacitive Array

Abstract

A device configured to sense a touch on a surface of the device. The device includes a cover and a force-sensing structure disposed below the cover. The force-sensing structure may be positioned below a display and used in combination with other force-sensing elements to estimate the force of a touch on the cover of a device.

1 - 20 . (canceled) 
     
     
         21 . An electronic device comprising:
 a cover;   a transparent touch sensor disposed below the cover and configured to detect a location of a touch on the cover;   a display disposed below the cover;   a force-sensing structure disposed below the cover and around a perimeter of the display and comprising:
 an upper capacitive electrode; 
 a lower capacitive electrode disposed below the upper capacitive electrode; 
 a compressible element disposed between the upper and lower capacitive electrodes; wherein the force-sensing structure is configured to produce an output that corresponds to an amount of force applied by the touch. 
   
     
     
         22 . The electronic device of  claim 21 , wherein:
 the electronic device further comprises a housing defining an opening in which the cover is positioned; and   the force-sensing structure forms a gasket between the housing and the cover.   
     
     
         23 . The electronic device of  claim 22 , wherein:
 the housing defines a bezel having a shelf surrounding the opening; and   the force-sensing structure is positioned between the shelf and a perimeter portion of the cover.   
     
     
         24 . The electronic device of  claim 21 , wherein:
 the force-sensing structure is a first force-sensing structure; and   the electronic device further comprises:
 a second force-sensing structure disposed below the display, wherein the second force-sensing structure comprises: 
 an upper capacitive layer; 
 a lower capacitive layer disposed below the upper capacitive layer; and 
 a compressible layer disposed between the upper and lower capacitive layers; and 
   a plate affixed to and supporting the second force-sensing structure.   
     
     
         25 . The electronic device of  claim 24 , wherein an air gap is located below the display and above the second force-sensing structure. 
     
     
         26 . The electronic device of  claim 21 , wherein the force-sensing structure comprises:
 a first force-sensing segment disposed along a first edge of the periphery of the cover; and   a second force-sensing segment disposed along a second edge of the periphery of the cover; and   the electronic device further comprises force-sensing circuitry operatively coupled to the first and second force-sensing segments and is configured to detect changes in capacitive coupling due to deflection of the first and second force-sensing segments and to produce a signal that corresponds to a magnitude the touch force on the cover.   
     
     
         27 . The electronic device of  claim 21 , wherein the force-sensing structure comprises:
 a first force-sensing segment disposed along a first edge of the periphery of the transparent touch sensor, the electronic device further comprising:   a second force-sensing segment disposed along a second edge of the periphery of the cover;   a third force-sensing segment disposed along a third edge of the periphery of the cover; and   a fourth force-sensing segment disposed along a fourth edge of the periphery of the cover,   wherein the second, third, and fourth force-sensing segments each comprise an upper capacitive electrode, a lower capacitive electrode, and a compressible element disposed between the upper and lower capacitive electrodes.   
     
     
         28 . The electronic device of  claim 21 , wherein:
 the electronic device further comprises:
 an enclosure having an opening; and 
 a display element disposed within the opening; and 
   the compressible element comprises a compliant sheet having a center opening through which the display is positioned.   
     
     
         29 . The electronic device of  claim 28 , wherein the compliant sheet includes multiple segmented compressible elements that define the opening. 
     
     
         30 . An electronic device comprising:
 a cover;   a first force-sensing structure disposed along a first edge of the cover and comprising a first pair of capacitive elements separated by a compressible layer; and   a second force-sensing structure disposed along a second edge of the cover and comprising a second pair of capacitive elements separated by the compressible layer.   
     
     
         31 . The electronic device of  claim 30 , further comprising:
 a third force-sensing structure disposed along a third edge of the cover and comprising a third pair of capacitive elements separated by the compressible layer; and   a fourth force-sensing structure disposed along a fourth edge of the cover and comprising a fourth pair of capacitive elements separated by the compressible layer.   
     
     
         32 . The electronic device of  claim 30 , further comprising a housing defining and opening having a shelf; wherein:
 the cover is positioned within the opening; and   the first and second force-sensing structures are positioned along the shelf of the housing.   
     
     
         33 . The electronic device of  claim 30 , wherein the compressible layer includes multiple segmented compressible elements. 
     
     
         34 . An electronic device comprising:
 a housing defining an opening;   a cover disposed within the opening;   a transparent touch sensor disposed below the cover and configured to detect a location of a touch on the cover;   a strain-sensitive layer disposed below the cover and configured to produce an output that corresponds to a deflection of the cover; and   a force-sensing structure disposed below the strain-sensitive layer, wherein an air gap is located between the strain-sensitive layer and the sheet sensor.   
     
     
         35 . The electronic device of  claim 34 , further comprising a support structure fixed relative to the housing and supporting the force-sensing structure. 
     
     
         36 . The electronic device of  claim 34 , wherein:
 the strain-sensitive layer comprises a capacitive electrode;   the force-sensing structure comprises an upper capacitive layer and a lower capacitive layer separated by a compressible layer; and   the capacitive electrode of the strain-sensitive layer is configured to capacitively couple to the upper capacitive layer of the force-sensing structure.   
     
     
         37 . The electronic device of  claim 36 , wherein:
 the electronic device further comprises sensing circuitry that is operatively coupled to the capacitive layer and the force-sensing structure; and   the sensing circuitry is configured to estimate the force of a touch on the cover based on a change in mutual capacitance between the capacitive electrode of the strain-sensitive layer and the upper capacitive layer of the force-sensing structure.   
     
     
         38 . The electronic device of  claim 37 , wherein the sensing circuitry is configured to:
 obtain a first capacitance between the upper capacitive layer and the lower capacitive layer of the force-sensing structure;   obtain a second capacitance between the capacitive electrode of the strain-sensitive layer and the upper capacitive layer of the force-sensing structure; and   generate an estimate of a force of a touch on the cover using the first and second capacitances.   
     
     
         39 . The electronic device of  claim 34 , further comprising:
 a display disposed between the cover and the force-sensing structure; and   the air gap is located between the display and the force-sensing structure.   
     
     
         40 . The electronic device of  claim 39 , wherein:
 the air gap is configured to at least partially collapse in response to a force of a touch that exceeds a first threshold; and   the first threshold is less than a second threshold that corresponds to a maximum force that can be detected by the strain-sensitive layer.