PATENT DOCUMENT

Publication Number: US-10180755-B2
Application Number: US-201615056679-A
Country: US
Kind Code: B2

Title: Electronic device with dynamic thresholding for force detection

Abstract:
The systems and techniques described herein generally relate to an electronic device having a touch-sensitive surface or region that is configured to receive force-based user input and dynamically adjust a force threshold used to recognize the force-based user input. In particular, the device may include one or more force sensors that are configured to detect a touch that exceeds a dynamically adjustable threshold. In some embodiments, the threshold is dynamically adjusted in response to a detected or estimated stability condition. By dynamically adjusting the threshold, the device may be better adapted or optimized for use with a particular support accessory or support configuration. In some cases, multiple sub-regions may be defined over the touch-sensitive surface, each sub-region having a different force threshold.

Claims:
What is claimed is: 
     
       1. A method for dynamically adjusting a minimum amount of force required to be registered by a force sensor that is coupled to a touch-sensitive surface in an electronic device to maintain the electronic device in a stable orientation on a supporting surface when a user touches the touch-sensitive surface, the method comprising:
 using a processor, determining a first angle of the touch-sensitive surface relative to the supporting surface based on data from at least one sensor; 
 using the processor, dynamically adjusting the minimum amount of force required to be registered by the force sensor for at least a portion of the touch-sensitive surface based on the first angle; 
 using the processor, determining a second angle of the touch-sensitive surface relative to the supporting surface based on data from the at least one sensor; 
 using the processor, dynamically adjusting the minimum amount of force to be registered by the force sensor for at least a portion of the touch-sensitive surface based on the second angle; and 
 using the processor, initiating a press-event signal in response to receiving a touch on the touch-sensitive surface that exceeds the minimum amount of force to be registered by the force sensor. 
 
     
     
       2. The method of  claim 1 , further comprising:
 using the processor, detecting a change in an angle of the touch-sensitive surface relative to the supporting surface based on data from the at least one sensor; and 
 using the processor, adjusting the minimum amount of force required to be registered by the force sensor for the portion of the touch-sensitive surface based on the detected change in the angle of the touch-sensitive surface. 
 
     
     
       3. The method of  claim 1 , further comprising:
 using the processor, detecting a movement of the electronic device in response to the touch on the touch-sensitive surface based on data from an additional sensor; and 
 in response to detecting the movement, reducing the minimum amount of force required to be registered by the force sensor for the touch-sensitive surface. 
 
     
     
       4. The method of  claim 1 , further comprising:
 using the processor, determining an angle of the touch-sensitive surface relative to the supporting surface based on data from the at least one sensor; 
 using the processor, determining a material of the supporting surface based on data gathered by an optical sensor; 
 using the processor, calculating a friction between the electronic device and the supporting surface based on the material of the supporting surface; 
 using the processor, calculating a static breaking torque of a pivot joint that is configured to hold the touch-sensitive surface at a fixed orientation; and 
 using the processor, calculating an amount of force that will cause the electronic device to tip based on the angle of the touch-sensitive surface, the friction, and the static breaking torque. 
 
     
     
       5. An electronic device on a supporting surface and configured to receive a touch input from a user, the electronic device comprising:
 a touch sensitive surface; 
 a force sensor that measures an amount of force applied to the touch-sensitive surface by the touch; and 
 a processing unit that determines an angle stability of the touch-sensitive surface with respect to the supporting surface using data from at least one sensor, dynamically adjusts a minimum amount of force required to be registered by the force sensor for the touch-sensitive surface based on the angle of the touch-sensitive surface, and initiates a signal in response to the touch input on the touch-sensitive surface that has a force greater than the minimum amount of force. 
 
     
     
       6. The electronic device of  claim 5 , wherein the minimum amount of force required to be registered by the force sensor is a first region-specific minimum force,
 wherein the processing unit dynamically adjusts a second region-specific minimum amount of force required to be registered by the force sensor for a second region of the touch-sensitive surface, and wherein the second region-specific minimum force is different than the first region-specific minimum force. 
 
     
     
       7. The electronic device of  claim 6 , wherein the processing unit further initiates a first signal in response to the touch being located in the first region and exceeding the first region-specific minimum force, and initiates a second signal in response to the touch being located in the second region and exceeding the second region-specific minimum force. 
     
     
       8. The electronic device of  claim 6 , wherein the minimum amount of force required to be registered by the force sensor is based, at least in part, on a distance between the location of the touch and a location of a pivot point and the first region is further from the pivot point than the second region. 
     
     
       9. The electronic device of  claim 8 , wherein the first region-specific minimum force is less than the second region-specific minimum force. 
     
     
       10. The electronic device of  claim 5 , wherein the minimum amount of force required to be registered by the force sensor is dynamically updated based on a change in the angle of the touch-sensitive surface with respect to the supporting surface. 
     
     
       11. The electronic device of  claim 5 , wherein the processing unit further detects movement due to the touch on the touch-sensitive surface of the electronic device, and reduces the minimum amount of force required to be registered by the force sensor in response to the detected movement. 
     
     
       12. The electronic device of  claim 5 , further comprising:
 an optical sensor, wherein the processing unit uses data from the optical sensor to determine at least one material of the supporting surface and wherein the processing unit calculates a friction between the electronic device and the supporting surface based on the at least one material. 
 
     
     
       13. The electronic device of  claim 5 , wherein the electronic device is configured to attach to a support accessory configured to support the electronic device, the electronic device further comprises a proximity sensor that the processing unit uses to detect a presence of the support accessory, and the processing unit dynamically adjusts the minimum amount of force required to be registered by the force sensor for the touch-sensitive surface based on the presence of the support accessory. 
     
     
       14. The electronic device of  claim 5 ,
 wherein the at least one sensor includes one or more of: an accelerometer, an inclinometer, a gyrometer, or a magnetometer. 
 
     
     
       15. An electronic device configured to receive a touch from a user, the electronic device comprising:
 an enclosure that attaches to a support structure, the support structure having a hinge about which the enclosure pivots; 
 a touch-sensitive surface coupled to the enclosure, the touch-sensitive surface having a first portion that is a first distance from the hinge and a second portion that is a second distance from the hinge; 
 a force sensor that measures an amount of a force applied to a touch-sensitive surface; and 
 a processing unit that adjusts a first minimum amount of force required to be registered by the force sensor at the first portion of the touch-sensitive surface based on the first distance, that adjusts a second minimum amount of force required to be registered by the force sensor at the second portion of the touch-sensitive surface based on the second distance, that initiates a first touch signal in response to receiving a first touch in the first portion of the touch-sensitive surface that exceeds the first minimum amount of force, and that initiates a second touch signal in response to receiving a second touch in the second portion of the touch-sensitive that exceeds the second minimum amount of force. 
 
     
     
       16. The electronic device of  claim 15 , wherein the electronic device rotates about the hinge when a torque exceeds a static threshold and when the touch from the user is below the first and second minimum amounts of force, the touch will not cause the electronic device to rotate about the hinge. 
     
     
       17. The electronic device of  claim 15 , wherein the support structure is supported by a surface of an external object, the electronic device further comprises an optical sensor, the processing unit determines at least one material of the surface of the external object based on data from the optical sensor, the processing unit determines an amount of friction between the support structure and the surface based on the at least one material, and the first and second minimum amounts of force are based, at least in part, on an the amount of friction. 
     
     
       18. The electronic device of  claim 16 , wherein the hinge is a ball-joint that rotates about multiple axes, and the first and second minimum amounts of force vary across both a length of the touch-sensitive surface and a width of the touch-sensitive surface.

Description:
FIELD 
     The described embodiments relate generally to electronic devices. More particularly, the present embodiments relate to electronic devices that use a dynamic or variable threshold to detect a force input. 
     BACKGROUND 
     Many modern electronic devices are configured to receive touch user input. Touch input may be used to initiate an action or control some aspect of the electronic device. Some electronic devices include a touch-sensitive display (e.g., touch screen) that covers a relatively large portion of the electronic device. However, in some instances, the performance of a large-area touch-sensitive display may depend on the rigidity or stability of the device. For example, the force of a touch on the display may, in some instances, cause the device to tip or slide, which may adversely affect the user experience and/or performance of the device. 
     SUMMARY 
     The embodiments described herein generally relate to an electronic device having a touch-sensitive surface or region that is configured to receive force-based user input. In particular, the device may include one or more force sensors that are configured to detect a touch that exceeds a predetermined force threshold. The device may be configured to initiate or generate a press-event signal in response to a touch that exceeds the force threshold, which may be interpreted as user input by the device or operating system. In some embodiments, the force threshold is dynamically adjusted in response to a detected or estimated stability condition in order to prevent tipping or undesirable movement of the device. By dynamically adjusting the threshold, touch user input for the device may be optimized for use with a particular mounting accessory or support configuration. In some cases, multiple sub-regions may be defined over the touch-sensitive surface, each sub-region having a different force threshold. 
     Some example embodiments are directed to a method for setting a force threshold for an electronic device having a touch-sensitive surface. A stability condition of the electronic device may be determined using one or more sensors (e.g., internal sensors). The force threshold may be reduced or modified for at least a portion of the touch-sensitive surface based on the stability condition. A press-event signal may be initiated or generated in response to receiving a touch on the touch-sensitive surface that exceeds the force threshold. In some embodiments, a change in the stability condition of the electronic device is detected and, in response, an updated force threshold is set for the portion of the touch-sensitive surface. The updated force threshold may be based on the detected change in the stability condition. 
     In some embodiments, the force threshold is dynamically updated based on an estimated change in an orientation of the electronic device. In some cases, the force threshold is dynamically updated based on a bouncing or undesired movement of the device. For example, determining the stability condition may include detecting a movement of at least a portion of the electronic device in response to the touch on the touch-sensitive surface (e.g., partial tipping or sliding). In response, an updated force threshold may be set for the portion of the touch-sensitive surface that is lower than the force threshold. 
     The estimate or determination of the stability condition may include any one of a variety of techniques. By way of example, estimating the stability condition may include one or more of: determining an orientation of the touch-sensitive surface; determining a support configuration for the electronic device; estimating a friction between the electronic device and a supporting surface of an external object; estimating a friction between a support structure attached to the electronic device and the supporting surface of the external object; estimating a static breaking torque of a pivot joint that is configured to maintain the touch-sensitive surface at a fixed orientation; or estimating a tipping condition using a location of the touch with respect to a pivot axis. 
     Some example embodiments are directed to an electronic device having a touch sensor configured to estimate a location of a touch on a touch-sensitive surface of the electronic device. The device may also include a force sensor configured to estimate an amount of force applied by the touch. The device may include a processing unit configured to: estimate a stability condition of the touch-sensitive surface, and define a force threshold for the touch-sensitive surface based on the stability condition. In some embodiments, the processing unit is further configured to initiate a press-event signal based a force of the touch and the force threshold. 
     In some cases, the threshold is a first region-specific threshold. The processing unit may be further configured to; define the first region-specific threshold with respect to a first region of the touch-sensitive surface based, and define a second region-specific threshold with respect to a second region of the touch-sensitive surface that is different than the first region and based, at least in part, on the stability condition. 
     The initiation or generation of a press-event signal may be dependent on the location of a touch with respect to the two or more regions. In some embodiments, in response to a touch being located in the first region and exceeding the first region-specific threshold, the processing unit may be configured to initiate a press-event signal. In response to the touch being located in the second region and exceeding the second region-specific threshold, the processing unit may be configured to initiate the press-event signal. 
     In some embodiments, the force threshold is based, at least in part, on a distance between a location of the touch and a location of a pivot point. The first region may be further from the pivot point than the second region. In some cases, the first region-specific threshold is less than the second region-specific threshold. 
     In some cases, the processing unit is configured to estimate an amount of movement caused in response to the touch on the touch-sensitive surface of the electronic device and, in response to the movement, reduce the force threshold. In some cases, the stability condition is based on an amount of friction between the electronic device and a supporting object. 
     In some embodiments, the electronic device is configured to attach to a support accessory configured to support the electronic device. The electronic device may also include a proximity sensor that detects a presence of the support accessory. The processing unit may be configured to estimate the stability condition using the proximity sensor. In some cases, the electronic device further comprises a sensor including one or more of: an accelerometer, an inclinometer, a gyrometer, or a magnetometer. The processing unit may be configured to estimate the stability condition using the sensor. 
     Some example embodiments are directed to an electronic device including an enclosure configured to attach to a support structure to define a pivot. The device may also include a force sensor configured to detect an amount of a force applied to a touch-sensitive surface. The device may also include a processing unit configured to define two or more force thresholds for two or more sub-regions within the touch-sensitive surface. The two or more force thresholds may depend, at least in part, on a distance between a respective sub-region and the pivot. 
     In some instances, the pivot defines an axis about which the electronic device will rotate when a torque exceeds a static threshold. In some cases, an input having a force at or below a respective threshold for the two or more force thresholds in a respective sub-region will not cause the electronic device to rotate about the axis. 
     In some embodiments, the support structure is supported by a surface of an external object. The two or more thresholds may be based, at least in part, on an estimated amount of friction between the support structure and the surface. In some embodiments, the support structure is an inclined support stand configured to rest on a surface of an external object. The pivot may be formed or defined along an edge between the support structure and the surface. 
     In some embodiments, the support structure is a support stand; the pivot is a hinged pivot within the support structure; and the hinged pivot is configured to remain immobile in response to a touch that is less than or equal to a respective force threshold of the two or more force thresholds applied to a respective sub-region. In some embodiments, the hinged pivot is a ball-joint pivot configured to rotate about multiple axes. The two or more thresholds may vary across both a length of the touch-sensitive surface and a width of the touch-sensitive surface. 
    
    
     
       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 having a touch-sensitive surface. 
         FIG. 2  depicts a cross-sectional view of the electronic device of  FIG. 1  viewed along section A-A of  FIG. 1 . 
         FIG. 3  depicts an example electronic device and an example mounting configuration. 
         FIG. 4  depicts a free-body diagram of the electronic device and mounting configuration of  FIG. 3 . 
         FIG. 5  depicts an example electronic device and an example support accessory. 
         FIG. 6  depicts an example display device having a support structure. 
         FIG. 7  depicts an example computing system having a support structure. 
         FIG. 8  depicts an example notebook computing system having a hinged display. 
         FIGS. 9-11  depict an example tablet computing system having multiple sub-regions defined over a touch-sensitive surface. 
         FIG. 12  depicts an example process for dynamically adjusting a force threshold of an electronic device. 
         FIG. 13  depicts example components of an electronic device. 
     
    
    
     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 following embodiments are directed to systems and techniques of providing a variable or dynamic force-detection threshold for an electronic device that is configured to prevent undesirable tipping or movement of the device during normal user interaction. Some example devices include a force sensor coupled to a force-sensitive or touch-sensitive surface that is configured to receive user touch and/or force input. The force sensor may be configured to detect an applied force and initiate a press-event signal in response to a touch on the surface that exceeds a force threshold. The press-event signal may be interpreted as user input by the device or operating system and may correspond to button push, a user selection of an object or other user-initiated command. 
     Generally, the force threshold may be defined or set with respect to one or more force sensors incorporated into the device. The force sensor may be integrated or operatively coupled to a cover glass sheet or other component that defines an exterior surface of the electronic device, and may be configured to produce a variable or scaled output that corresponds to an amount of force applied to the exterior surface of the electronic device. An applied force that is greater than the force threshold may trigger a press-event or force-event signal which may be used alone or in conjunction with other input to control the electronic device. For example, the output of the force sensor may be used in conjunction with a location output of a touch sensor, such as a capacitive array of a touch screen, to interpret touch user input for a graphical user interface. 
     The amount of threshold that is used to initiate a force- or press-event may vary depending on a current mounting or support configuration of the electronic device. In some embodiments, the force threshold may be dynamically adjusted based on an estimated stability condition. In general, a stability condition may include a mounting configuration, device orientation, physical constraint, environmental condition, or other factor that may affect the stability of a touch-sensitive surface when receiving touch and/or force input. A stability condition may be estimated by measuring various measurements including, for example, a measurement of an angle or orientation of the device, an estimation of friction between the device and a supporting surface, an estimation of a static breaking force of a pivot joint, an estimation of a tipping condition, a detection of the presence of a particular support structure or support accessory, and so on. 
     By way of example, an electronic device, such as a tablet device may include a touch screen that is configured to receive touch and/or force input. In accordance with some embodiments, the tablet device may be configured to detect that it is being used in an inclined or upright orientation that is consistent with use of an inclined stand or support structure. In such a condition, excessive force on the touch screen of the tablet may cause the device to tip or slide. In response to determining that the stability condition (e.g., attachment of a stand or support structure) is one that is prone to tipping or sliding, the force threshold may be dynamically reduced or adjusted to help prevent movement of the device during normal touch interactions with the touch screen. The reduction in the force threshold may reduce the pressure or force required in order to trigger a press-event signal used for certain user input commands. 
     A stability condition, such as an orientation or placement of the device, may be detected using one or more internal sensors, the output of which may be used to determine or adjust the dynamic force threshold. For example, one or more internal sensors may be used to estimate conditions that are consistent with a particular mounting configuration. More specifically, one or more internal sensors may be used to detect a sustained orientation or position that is consistent with an incline angle associated with a particular support accessory, such as a stand. In some cases, an estimated stability condition may be based on the detection of an attachment or proximity of a particular support accessory. The force threshold may be dynamically adjusted in accordance with the estimated stability condition to reduce the likelihood that the device will become unstable due to normal touch input. 
     In accordance with some embodiments, multiple region-specific force thresholds may be defined over the touch-sensitive surface in accordance with a particular stability condition or mounting configuration. Some mounting or support configurations may define a pivot point or pivot axis about which the device may rotate if subjected to a sufficient torque. In such cases, the distance of a touch from the pivot point or pivot axis may be used to determine or adjust the dynamic force threshold. By way of example, a region that is further from a pivot point or pivot axis may have a region-specific threshold that is lower or reduced as compared to a region that is closer to a pivot point or pivot axis. Additionally or alternatively, region-specific thresholds may be adjusted or tailored to account for a potential translational slip or shift due to a frictional interface between two components or a component and a supporting object, such as a table top. An individual or unique force threshold may be assigned to each respective sub-regions that are defined for a particular mounting or support configuration. 
     These and other embodiments are discussed below with reference to  FIGS. 1-13  described below. 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 having a touch-sensitive surface that is configured to receive force-input from a user. By way of example, the device  100  may include an enclosure  102  surrounding a display  104  that is positioned below a touch-sensitive surface  110  or touch-sensitive region. The touch-sensitive surface  110  may be defined over a portion of the cover sheet  106  and/or other element that forms a portion of an external surface of the device  100 . One or more force sensors and/or touch sensors may be operatively coupled to the touch-sensitive surface  110  and configured to receive touch input from an object, such as a user&#39;s finger  120 . 
     The device  100  may be configured to initiate or generate a force- or press-event signal in response to a touch on the touch-sensitive surface  110  that exceeds a force threshold. The force- or press-event signal may be interpreted as user input and used to control aspects of the device. For example, the device  100  may initiate or generate a press-event signal in response to a press by a finger  120  that exceeds a force threshold and, in response, recognize a user-selection of an object depicted on the display  104 . In some implementations, multiple force thresholds may be defined, each corresponding to a different type of user input. For example, a first force threshold may be associated with first operation (e.g., an object selection). A second force threshold, greater than the first force threshold, may be associated with a second operation (e.g., view a preview or drill-down operation) that is different than the first operation. In some embodiments, the device  100  may be configured to use a touch sensor in addition to, or in conjunction with, the one or more force sensors to interpret a wide range of user input commands including, for example, cursor movement, object selection, touch gestures, and other forms of user input. 
     As described with respect to various embodiments described herein, the force threshold may be dynamically adjustable based on a detected or estimated stability condition, which may correspond to a particular mounting or support configuration of the device  100 . The stability condition or support configuration may be detected using one or more internal sensors, user input, or other type of signal or data. In one example, the force threshold may be set to a maximum or nominal state when it is estimated that the device  100  is placed flat on a surface or held in the user&#39;s hands. The force threshold may be lowered or reduced in response to an estimated stability condition. For example, the force threshold may be lowered if it is estimated that the device is placed in an elevated or tilted configuration that may be prone to tipping or sliding. Various example mounting or support configurations are described below with respect to  FIGS. 3-8 . 
       FIG. 1  depicts a non-limiting example of an electronic device  100  in accordance with some embodiments. In particular, the electronic device  100  is depicted as a tablet computing device. In other examples, the electronic device  100  may include a variety of portable electronic devices including, without limitation, a mobile phone, a portable media player, or other similar devices. The embodiments described herein may also be used in conjunction with a variety of other types of devices including, for example, a notebook computer, a computer display device, a desktop computer, an electronic appliance, and so on. The embodiments may also be used in conjunction with a wearable electronic device, such as a smart watch, timekeeping device, health monitoring device, and other similar devices. 
     With regard to  FIG. 1 , the device  100  includes an enclosure  102  that defines an opening in a front or upper portion of the device  100 . The display  104  may be at least partially disposed within the opening of the enclosure  102  and be surrounded by a bezel or border region of the enclosure  102 . In some examples, the display  104  forms nearly the entire front or upper portion of the device without a bezel or border region. A transparent cover sheet  106  may be disposed over the display  104  to form an exterior or external surface of the device  100 . The cover sheet  106  may be formed from a translucent material such at plastic, glass, sapphire, zirconia or the like. 
     The cover sheet  106  and touch sensor (depicted in  FIG. 2 ) may define the touch-sensitive surface  110  on the upper or front surface of the device  100 . In this example, the touch-sensitive surface  110  is substantially congruent with a display area of the display  104 . In general, the touch-sensitive surface  110  together with the display  104  may be referred to as a touch screen or touch-sensitive display. 
     As described in more detail below with respect to  FIG. 2 , the touch-sensitive surface  110  may be operably coupled to one more force sensors and/or touch sensors that are configured to sense touch input from a user. In accordance with the embodiments described herein, the force threshold used to interpret the touch or force input on the touch-sensitive surface  110  may be dynamically adjusted based on an orientation and/or mounting or support configuration of the device  100 . 
     As shown in  FIG. 1 , the device  100  may also include one or more additional user-input devices, such as a button  108 . In some embodiments, the button  108  may also include one or more force sensors that are configured to initiate a press-event signal in response to a touch that exceeds a threshold. In accordance with some embodiments, the threshold for the button  108  may also be dynamically adjusted based on stability condition associated with an orientation and/or mounting configuration. Alternatively, the button  108  may include a mechanical switch, such as a dome switch having a substantially fixed or non-adjustable force threshold. While the example of  FIG. 1  is provided as one illustrative embodiment, variations in the configuration or specific layout of the components of the device  100  may vary. 
       FIG. 2  depicts a cross-sectional view of the electronic device of  FIG. 1  viewed along section A-A. The cross-sectional view of  FIG. 2  illustrates the various components that may be used to form the touch sensitive surface  110  of the device  100 . Many internal components, such as a processing unit, computer memory, battery, and other components of the device  100  are omitted from  FIG. 2  for clarity.  FIG. 13 , described below, provides another non-limiting example of internal components of an electronic device which may be included in the device  100  of  FIGS. 1 and 2 . 
     As shown in  FIG. 2 , the device  100  includes a cover sheet  106  that forms at least a portion of the external or exterior surface of the electronic device. The cover sheet  106  may be attached directly to the enclosure  102  or may be attached via a gasket, seal, or other coupling component. As described above, the cover sheet  106  (or cover) may be formed from a translucent material such as a polyethylene terephthalate (PET), amorphous glass, or crystalline ceramic, such as sapphire or zirconia. 
     In the example of  FIG. 2 , a touch sensor  204  is positioned below the cover sheet  106 . The touch sensor  204  may include an array of capacitive electrodes that is configured to detect the location of a touch on the touch-sensitive surface  110  of the device  100 . The touch sensor  204  may operate in accordance with a mutually-capacitive, self-capacitive, or other type of capacitive sensing scheme. In some embodiments, the touch sensor  204  may include a resistive, inductive, ultrasonic, or other type of sensor configured to detect the presence and location of a touch on the touch-sensitive surface  110 . 
     As shown in  FIG. 2 , a force sensor  202  is also positioned below the cover sheet  106 . While in this example the force sensor  202  is depicted as being disposed below the touch sensor  204 , the order and position of the layers may vary depending on the implementation. The force sensor  202  may operate in accordance with various force-sensing schemes or configurations. For purposes of illustration, the force sensor  202  is depicted as a single layer within the display stack. However, the force sensor  202  may include multiple layers positioned in various locations within the display stack. Additionally or alternatively, the force sensor  202  may be formed around the periphery or around a region of the display  104 . The force sensor  202  may also be integrally formed with a seal or gasket that is positioned between the cover sheet  106  and the enclosure  102 . 
     In one embodiment, the force sensor  202  is formed from one or more strain-sensitive layers that are configured to produce an electrical output or exhibit a change in an electrical property in accordance with an amount of strain or deflection of the cover sheet  106 . For example, the force sensor  202  may include a piezo-electric or piezo-resistive material that produces a charge or exhibits a change in resistance in response to a deflection of the cover sheet  106 . The amount of force of a touch on the touch-sensitive surface  110  may correspond to the amount of deflection of the cover sheet  106  and/or the force sensor  202 . 
     In another embodiment, the force sensor  202  may include a capacitive sensor that includes a pair of capacitive electrodes positioned on opposite sides of a compressible layer or air gap. An amount of force may be detected by measuring deflection of the compressible layer or air gap using a change in capacitance between the pair of capacitive electrodes. The capacitive sensor may be positioned within a single layer, as depicted in  FIG. 2 . Additionally or alternatively, a capacitive force sensor may be positioned along one or more edges of the display  104  or may be located between the cover sheet  106  and the enclosure  102 . 
     While in  FIG. 2 , the force sensor  202  is depicted as being integrated with the display stack, in some embodiments a force sensor may be integrated with an object, such as a stylus, that is configured to interact with the display stack or another surface of the device  100 . For example, a pressure-sensitive force sensor may be operatively coupled to the tip of a stylus and used to determine the force applied by the stylus to an external surface of the device  100 . Such a force sensor may replace the example force sensor  202  of  FIG. 2  or may be used in conjunction with the force sensor  202 . 
     As shown in  FIG. 2 , the display  104  is also positioned below the cover sheet  106  and may be at least partially positioned within the opening defined by the enclosure  102 . The display  104  may include any one of a variety of display technologies including, for example, an liquid crystal display (LCD), organic light emitting diode (OLED) display, electroluminescent (EL) display, and so on. While depicted as separate and distinct components in the example of  FIG. 2 , in some embodiments, one or more of the force sensor  202  and/or the touch sensor  204  may be integrally formed with the display  104 . 
     Whether integrated into the device  100  or other object, such as a stylus, the force sensor  202  may be configured to generate an electrical output that may be used to initiate a force-event signal or press-event signal. The force- or press-event signal may be interpreted as user input to control various aspects of the device. The output from the force sensor  202  may be used alone or in conjunction with the output of the touch sensor  204  to interpret a wide variety of user input on the touch-sensitive surface  110 . 
     As discussed previously, the device may be configured to dynamically adjust one or more thresholds associated with the force sensor  204  depending on a stability condition which may correlate to a mounting or support configuration of the device. For example, the force threshold may be dynamically reduced when the device is being used in conjunction with a particular support accessory or estimated to have a support configuration that is prone to tipping or otherwise having a reduced or impaired stability. 
       FIG. 3  depicts an example tablet computing system having an example support accessory. In the non-limiting example of  FIG. 3 , the device is attached a support stand  320  that is configured to support the device  100  in an inclined or upright position. The support stand  320  may be configured to rest on a support surface of an external object, such as a table or desk. 
     In the present non-limiting example, the support stand  320  is formed from a magnetic cover accessory that is configured to fold into the support configuration depicted in  FIG. 3 . In particular, the support stand  320  includes multiple segments that are flexibly coupled together by respective hinges or flexible portions. The support stand  320  may be reconfigurable to provide both a protective cover and support stand functionalities. In a first configuration, the support stand  320  may be configured to be flattened into a cover configuration such that each of the multiple segments lies flat across the touch-sensitive surface  110  of the device  100 . This may help prevent the touch-sensitive surface  110  from receiving accidental touch input and protect the cover sheet and display. In a second configuration, the segments of the support stand  320  may be folded to provide a support stand, as depicted in  FIG. 3 . The segments of the support stand  320  may include magnetic elements that are configured to couple to the exterior surface of the device  100  and may help to hold the support stand  320  in the first and/or second configuration. 
     As shown in  FIG. 3 , the device  100  may be configured to receive touch input on the touch-sensitive surface  110 . An object, such as a user&#39;s finger  310  or a stylus  312 , may be used to provide touch input to the touch-sensitive surface  110 . As described above with respect to  FIG. 2  above, the touch-sensitive surface  110  may be operatively coupled to a touch sensor that is configured to detect the location of a touch on the surface. The touch-sensitive surface  110  may also be operatively coupled to a force sensor that is configured to produce a variable or scaled output that corresponds to the force of a touch exerted by the user&#39;s finger  310  and/or the stylus  312 . As discussed above with respect to  FIG. 2 , one or more force sensors may be integrated within the touch-sensitive surface  110  of the device  100 , integrated with the stylus  312 , or a combination of the two. 
     In the present example, the support stand  320  defines a pivot axis  322  about which the device  100  will rotate or tip if excessive force is applied to the touch-sensitive surface  110 . The pivot axis  322  is defined along an interface between the rear edge of the support stand  320  and the supporting surface of an external object, such as a table or desk. Typically, the device  100  and the support stand  320  will remain stable unless a torque that exceeds a static limit is exerted on the device  100 , which may be the result of an excessive force from the user&#39;s finger  310  or another object such as the stylus  312 . 
     In some embodiments, a force threshold, used to trigger a press-event signal or otherwise recognize force input, may be dynamically adjusted based on a detected or estimated stability condition or support configuration. In particular, the device  100  may be configured to detect a stability condition or mounting configuration based on one or more internal sensors and/or other signals or data and, in response, dynamically adjust the force threshold. 
     In one example, the force threshold may be reduced for the entire touch-sensitive surface  110  based on an estimated maximum force that can be applied without impairing the stability of the device  100 . The maximum force may be determined based on a stability condition associated with a particular mounting or support configuration that is detected by the device. For example, the device  100  may be configured to detect an inclined stand-type mounting configuration using an internal orientation sensor, such as an accelerometer, an inclinometer, a tilt sensor, or other similar device. In one embodiment, the device  100  is configured to determine the support configuration if, for example, the orientation of the device has remained at a fixed angle for a particular period of time. In some cases, if the device is positioned at a non-changing or relatively fixed angle for a sustained period of time (e.g., longer than several seconds) and the angle corresponds to an incline angle associated with the support stand  320 , the device  100  may determine that the device  100  is attached to and supported by the support stand  320 . In some cases, the device  100  may estimate a stability condition by simply measuring or estimating the fixed angle, which may correspond to the incline angle associated with the support stand  320 . 
     Additionally or alternatively, the device  100  may be configured to directly detect the presence of the support stand  320  in order to determine a stability condition. In one embodiment, the support stand  320  includes a magnet, electrical contact, or other identifiable element that may be sensed by the device  100  and used to determine the presence of the support stand  320 . The device  100  may also be configured to receive an electrical signal from the support stand  320  that can be used to detect its presence and/or configuration. In some embodiments, the device  100  may be configured to receive a user selection or user input that indicates that the support stand  320  is attached to the device  100 . 
     In response to a determination that the support stand  320  is attached to the device  100  or an estimation that the device  100  has a stability condition consistent with an inclined and externally-supported support configuration, the device may be configured to adjust the dynamic force threshold used to recognize force-based touch events.  FIG. 4  depicts an example free-body diagram of the electronic device  100  and support stand  320  of  FIG. 3  having a force applied at a location of the touch-sensitive surface  110 . 
     With reference to  FIG. 4 , the device  100  may be configured to determine a maximum force F t max  that can be applied to the touch-sensitive surface  110  without exceeding a static limit. For example, an applied force that exceeds F t max  may cause the device  100  (and support stand  320 ) to tip or rotate about the pivot axis  322 . This calculation may be based on the amount of force of a touch F t max  that causes a user-input torque that exceeds the static torque defined, in part, by the center of gravity of the device. A sample estimation may be based on the following relationship: 
                       F     t   ⁢           ⁢   max       =       W   ×     D   w         D   f         ,           Equation   ⁢           ⁢   1               
where F t max  is the maximum force that can be applied without tipping, D f  is the distance from the location of the touch to the pivot axis  322 , W is the weight of the device, and D w  is the distance from the center of gravity of the device  100  to the pivot axis  322 . Alternatively, D f  may be defined as the distance from the upper-most edge of the touch-sensitive surface  110  to the pivot axis  322 . Formally, the value F t max  represents the component of the touch force that is perpendicular to a hypothetical line that extends from the point of touch on the touch-sensitive surface  110  and the axis  322 . However, if the device  100  is nearly vertical, as shown in  FIG. 4 , the value F t max  may be sufficiently approximated as the amount of force applied to the touch-sensitive surface  110 .
 
     Using the relationship expressed in Equation 1, or a similar technique, the force threshold of the device  100  may be adjusted to a value such that a touch having a force less than or equal to F t max  may be used to trigger or initiate a force-event signal or press-event signal. In some cases, multiple force thresholds may be defined, each force threshold associated with a different operation or set of operations. For example, a first threshold may be associated with a selection operation and a second, higher threshold may be associated with a preview or drill-down operation. As a result, normal touch or force input on the touch-sensitive surface  110  may not cause the device to tip or rotate about the axis  322 . 
     In another example, the force threshold may be reduced for a portion or sub-region of the touch-sensitive surface  110  based on an estimated maximum torque. Similar to the example described above, the device  100  may be configured to determine or estimate a support configuration associated with the attachment of the support stand  320  and the pivot axis  322 . The device  100  may be further configured to define multiple sub-regions within the touch-sensitive surface  110 , each sub-region having a different region-specific threshold. Also similar to the example discussed above, each region-specific threshold may be determined based on a force that is estimated to overcome the static weight of the device  100  and cause rotation about the axis  322 . A sample estimation for a maximum force F region max  for each sub-region may be based on the following relationship: 
                       F     region   ⁢           ⁢   max       =       W   ×     D   w         D   region         ,           Equation   ⁢           ⁢   2               
where F region max  is the maximum force that can be applied without tipping, D region  is the distance from the top of the region to the pivot axis  322 , W is the weight of the device, and D w  is the distance from the center of gravity of the device  100  to the pivot axis  322 .
 
     Using the relationship expressed in Equation 2, or a similar technique, the force threshold (or group of force thresholds) of each region may be dynamically adjusted to a value such that a touch having a force less than or equal to F region max  may be used to initiate or generate a force-event signal or press-event signal. One advantage to using this approach is that a greater force can be used for regions that are closer to the pivot axis  322  because it is more difficult to tip the device when pushing on a lower portion of the screen. Example sub-regions that may be used in accordance with this technique are described below with respect to  FIGS. 9-11 . 
     In another example, the force threshold may be reduced for all or a portion of the touch-sensitive surface  110  based on an estimated maximum friction. In particular, the force threshold may be determined based on an estimated amount of force required to push the device  100  (and support stand  320 ) across a supporting surface, such as a table top. Similar to the previous examples, the device  100  may be configured to estimate a mounting configuration based on one or more sensors or other input. 
     In addition, the device  100  may be configured to detect one or more properties of the mounting surface and estimate a maximum force based on an estimated friction. In one example, the device  100  is configured to use an optical sensor, such as the onboard camera or other optical device, to determine the type of surface that is under the support stand  320  supporting the device  100 . Based on the optical properties, such as a specular or diffuse reflection property, the device  100  may be configured to estimate the friction between the support stand  320  and the surface. The device  100  may also be configured to detect the type of material (e.g., wood, metal, laminate countertop) using an optical sensor and an analysis of the surface texture and/or color of the surface. The device  100  may be configured to use one or more other types of sensors, such as acoustic sensors (e.g., a speaker and/or microphone) to determine properties of the surface in order to estimate the friction. 
     Additionally or alternatively to the techniques described above, the device  100  may be configured to use a default or fixed frictional estimate to determine the dynamic force threshold. In general, the dynamic threshold may be adjusted based on the following relationship:
 
 F   friction max   =μ×W,   Equation 3
 
where F friction max  is the maximum force that can be applied without causing the device to slide, μ is the estimated friction between the support stand  320  and the supporting surface, and W is the weight of the device. Using the relationship expressed in Equation 3, or a similar technique, the force threshold of the device  100  may be adjusted to a value such that a touch having a force less than or equal to F friction max  may be used to initiate or generate a force-event signal or press-event signal.
 
     The frictional force limit described with respect to Equation 3 may be implemented in conjunction with the one or both of the tipping limits described with respect to Equations 1 and 2. For example, in some implementations, both a theoretical tipping limit and a frictional limit may be computed or estimated using one of the above-described techniques. A dynamic force threshold may be defined based on the lesser of the tipping limit (e.g., F t max  or F region max ) and the frictional limit (e.g., F friction max ). Alternatively, both the tipping and frictional limit may be modeled as a single function or modeling relationship. Regardless of the underlying model or relationship, the dynamic threshold may be computed or estimated using a simplified mathematical equation, look-up table, or other similar implementation. 
     The dynamic force threshold may depend, in part, on the location of the touch, which may determine if a tipping limit or a frictional limit dominates. For example, a touch located closer to the pivot axis  322  may be dominated by a frictional limit as an excessive force may tend to cause the device to translate or slip. In contrast, a touch located further from the pivot axis  322  may be dominated by a tipping limit as an excessive force may cause the device to tip or rotate rather than slip. In some implementations, a transition line or region may be defined with respect to the touch-sensitive surface  110  at which the device transitions from a tipping limit to a frictional limit (or frictional limit to tipping limit) in computing the dynamic force threshold. 
     In another example, a dynamic threshold may be defined based on a sensed movement of the device  100 . For example, one or more internal sensors, such as an accelerometer, a gyrometer, an inclinometer, or other position/movement sensor, may be used to determine if the device is tipping and/or sliding in response to touch input on the touch-sensitive surface  110 . For example, the device  100  may be configured to detect momentary tipping or shifting of the device in response to interaction with the touch-sensitive surface  110 . In some cases, in response to detecting an undesirable level of movement, the device  100  may be configured to reduce the force threshold used to initiate a force- or press-event. In some cases, the force threshold is incrementally reduced until the movement of the device reaches an acceptable level. Additionally or alternatively, an alarm or alert may be generated in response to a tipping and/or sliding in response to touch input on the touch-sensitive surface  110 . In some cases, the force threshold may be reset to a default or nominal value if the device  100  does not move again for a predetermined period of time. 
     A dynamic force threshold or force limit calculation (e.g., F t max , F region max , F friction max ) may be used to trigger one or more countermeasures to prevent movement or potential damage to the device  100 . In one example embodiment, an estimation of a force limit or threshold such as F t max  may be used to generate an alarm or alert that the device is about to tip. In this case, a user press or touch that is at or near the F t max  value may cause the device to produce an audible, haptic, and/or visual alarm or alert that is intended to notify the user that the device  100  is about to become unstable. In some implementations, an additional force threshold may be defined that may be used to trigger or generate an alarm or alert. The additional force threshold may be greater than the force threshold used to initiate a force-event signal, but less than or equal to the F t max  value. 
     In another example embodiment, an estimation of a force limit or threshold, such as F t max , may be used to trigger or initiate a state or mode of operation for the device  100 . For example, based on a force limit or threshold, the device  100  may initiate a safe or protection mode, which may be configured to reduce or prevent damage due to a tipping or falling event. In one implementation, the device  100  may enter or initiate a safe mode in response to receiving a forceful touch that exceeds a force limit or threshold. The safe mode may momentarily suspend one or more operations to prevent the loss of data or damage due to a tipping, falling or other impact-causing event, which may be caused by the forceful touch. Additionally or alternatively, the safe mode may deploy a mechanical countermeasure, such as a bumper, bladder, mechanical lockout, or other similar mechanism, that is configured to reduce or prevent damage to the device  100  due to a tipping, falling, or other impact-causing event. 
     A dynamic force threshold or force limit calculation (e.g., F t max , F region max , F friction max ) may be used to raise the threshold. For example, if it is estimated that the stability condition is capable of withstanding a greater amount of force without becoming unstable or moving, the force threshold used to initiate a press-event signal may be increased. Additionally, if it determined that the device  100  is being transported or being used in a dynamic environment (e.g., in vehicle on a bumpy road), the threshold may be increased to reduce incidental or accidental touches from initiating press-event signals. In some cases, the device  100  may be configured to reject, suppress, or ignore touches and/or forceful touches in response to a determination that the device  100  is being transported or being used in a dynamic environment. The device  100  may use one or more motion sensors (e.g., accelerometers, gyrometers, global positioning signals, and the like) to determine that the device  100  is in a dynamic environment and/or is being transported. 
     These examples are illustrative with respect to the specific support configuration depicted in  FIGS. 3 and 4  and are not intended to be limiting. The specific calculations used to determine the dynamic force threshold may vary depending on the support and/or mounting configuration used.  FIGS. 5-8  depict additional example mounting configurations that may also use a dynamic thresholding in accordance with some embodiments. 
       FIG. 5  depicts an example electronic device and an example support accessory. Similar to the previous example, the device  500  may be coupled to a support structure, in this case, a stand  520 . Similar to the previous example, the stand  520  is configured to support the device in an upright or inclined orientation. The device  500  may be a mobile phone, portable media player, or other portable electronic device having a touch-sensitive surface  510  that is configured to receive force input. The device  500  may include similar features and elements as described above with respect to device  100  in  FIGS. 1-4 , above. 
     As shown in  FIG. 5 , the stand  520  may define a pivot point or pivot axis  522  about which the device  500  will rotate if a torque exceeding a static limit is exceeded. For example, the static limit may be a static torque corresponding the weight and center of gravity of the device  500  and stand  520 . Similar to the examples provided above with respect to  FIG. 3 , a dynamic force threshold (or thresholds) may be defined to reduce the possibility of tipping about axis  522  and/or sliding across a support surface due to the force of touch input on the touch-sensitive surface  510 . Using similar techniques described above with respect to  FIG. 3  and Equations 1-3, the device  500  may determine or define a dynamic threshold that is determined based on a support condition associated with the mounting configuration depicted in  FIG. 5 . 
     While the stand  520  of  FIG. 5  is depicted as a rigid structure, in some embodiments, the stand  520  may include one or more hinge joints that allow the stand  520  to be folded or flattened. The hinge joints may be locked or otherwise secured when the device  500  is in use to provide a substantially rigid support structure for the device  500 . In some implementations, the stand  520  is a dual purpose accessory and, in one mode, may be used to support the device  500  and, in another mode, be used to protect or cover the device  500 . 
     The stand  520  may be removably attached to the device  500  or, alternatively, the stand  520  may be integrally formed with the enclosure or another component of the device  500 . In some implementations, the stand  520  may be integrally formed within the device housing or enclosure. For example, the stand  520  may be formed from a portion of the housing or enclosure of the device that includes a feature or element that protrudes or extends outward to support the device  500  in an inclined position, as shown in  FIG. 5 . In some implementations, the stand  520  is integrally formed with a protective case that is attached to the enclosure of the device  500 . For example, such a protective case may be configured to provide physical protection for the device  500  and also include one or more features for supporting the device  500  in an inclined position, as shown in  FIG. 5 . 
       FIG. 6  depicts an example display device having a support structure. In this example, a display device  600  includes a touch-sensitive surface  610  that is configured to detect both a location and a magnitude of force on the front of the display device  600 . The display device  600  may be operatively coupled to a stand-alone computer system such as a desktop or terminal computer system. As shown in  FIG. 6 , the display device  600  may include a support stand  620  that is configured to rest or be supported by a surface of an external object, such as a desk or table. The support stand  620  may define one or more pivots  622 ,  624  about which the display device  600  may rotate if a torque is applied that exceeds the static limits. 
     In particular, as shown in  FIG. 6 , the support stand  620  defines a hinged pivot  622  that allows for the adjustment or movement of the display  600 . The hinged pivot  622  may be configured to be locked or fixed when not being adjusted. The hinged pivot  622  may, for example, be configured to hold or maintain the display  600  at a fixed orientation during normal or predicted operating conditions. In some cases, the hinged pivot  622  may include a mechanical clutch or engagement that prevents movement if a static breaking torque is not exceeded. In accordance with some embodiments, the force threshold of the display  600  may be dynamically adjusted to reduce the chance that the static breaking torque of the hinged pivot  622  will be exceeded. A sample estimation of the maximum touch force F t max  may be based on the following relationship: 
                       F     t   ⁢           ⁢   max       =       T   static       D   t         ,           Equation   ⁢           ⁢   4               
where F t max  is the maximum force that can be applied without causing the display to move, D t  is the distance from the top of the touch-sensitive surface  610  to the hinged pivot  622 , and T static  is the static breaking torque that hinged pivot  622  can resist. Accordingly, the dynamic threshold may be set to a value that is less than or equal to F t max  based on the relationship of Equation 4. Similarly, multiple thresholds may be defined for multiple respective sub-regions using Equation 4 and using the distance between the sub-region and the hinged pivot  622  for the value D t .
 
     In some embodiments, the hinged pivot  622  may have a variable or adjustable static breaking torque. For example, the hinged pivot may include a tensioning or tightening electromechanical or mechanical system that increases or decreases the static breaking torque, such as an adjustable clutch or variable friction coupling. In some implementations, the static breaking torque may be adjusted or varied in response to a touch in a particular location or region. For example, the static breaking torque T static  may be increased in response to a touch near the edge of the display  600  in order to prevent or reduce the chance of rotation of the display  600  due to the force of a touch. The static breaking torque T static  may also be adjusted (e.g., increased) in response or in accordance with an adjusted force threshold. For example, an adjusted force threshold may be computed using a nominal or baseline breaking torque value. The actual static breaking torque of the hinged pivot  622  may then be increased to provide a more rigid support to further reduce the probability that the display  600  will move in response to touch interaction with the touch-sensitive surface  610 . 
     Additionally, similar to the previous examples, the support stand  620  defines an inherent tipping axis or pivot  624  defined along an edge of an interface between the support stand  620  and the supporting surface. The tipping axis or pivot  624  is the point or axis about which the display  600  will rotate or tip if a torque that exceeds the static weight of the display device  600  is exceeded. Similar to the previous examples described above with respect to  FIG. 3  and Equations 1 and 2, one or more dynamic force thresholds may be defined based on the location of the tipping axis or pivot  624 . Also, similar to the previous example provided above with respect to  FIG. 3  and Equation 3, a dynamic force threshold may be determined based on an estimated friction between an interface between the support stand  620  and the supporting surface of an external object such as a table or desk. 
       FIG. 7  depicts an example computing system having a support structure. In this example, a computing system  700  includes a touch-sensitive surface  710  that is configured to detect both a location and a magnitude of force on a display portion of the computing system  700 . As shown in  FIG. 7 , the computing system  700  may include a support stand  720  that defines one or more pivot points or pivot axes about which the display portion may rotate if a torque is applied that exceeds the static limits. 
     In particular, as shown in  FIG. 7 , the support stand  720  defines two hinged pivots  722  and  724  that allows for the adjustment or movement of the display portion of the computing system  700 . Similar to the previous examples, the hinged pivots  722  and  724  may be configured to be locked or fixed when not being adjusted. In some cases, the hinged pivots  722  and  724  may include a mechanical clutch or engagement that prevents movement or is otherwise immobile if a static breaking torque is not exceeded. In particular, the hinged pivots  722  and  724  may remain immobile of the force of a touch results in a torque that is less than or equal to the static breaking torque of the respective hinged pivots  722  and  724 . In accordance with some embodiments, the force threshold of the computing system  700  may be dynamically adjusted to reduce the chance that the static breaking torque of the hinged pivots  722  and  724  will be exceeded. The dynamic threshold may be computed using a relationship similar to the one described in Equation 4 with respect to  FIG. 6 , above. Accordingly, the hinged pivots  722  and  724  may be configured to remain immobile in response to a touch that is less than or equal to the dynamic threshold. 
     In this example, the upper hinged pivot  722  is a ball joint that is configured to rotate about multiple axes. Specifically, the upper hinged pivot  722  allows the display portion to tilt up and down as well as side-to-side. The ball joint may also allow the display portion to rotate in-plane about the center of the display. The ball joint may have a static torque that resists unintentional rotation of the display portion. To help reduce unintentional movement due to normal touch interaction with the touch-sensitive surface  710 , multiple region-specific thresholds may be defined over the touch-sensitive surface  710 . 
     In some embodiments, the force threshold may vary along the two-dimensional touch-sensitive surface  710 . In particular, the force threshold may vary along a horizontal direction (e.g., x-direction) such that the force threshold decreases with distance from the center of the upper hinged pivot  722 . Similarly, the force threshold may vary along a vertical direction (e.g., y-direction) such that the force threshold decreases with distance from the center of the upper hinged pivot  722 . Example region-specific threshold configurations in accordance with this embodiment are described in more detail below with respect to  FIGS. 10 and 11 . 
     Similar to the example provided above with respect to  FIG. 6 , the static breaking torque of the hinged pivots  722  and  724  of  FIG. 7  may be dynamically adjusted or varied in response to force threshold calculation and/or to a touch on the touch-sensitive surface. For example, the static breaking torque may be increased in response to a touch near the edge of the touch-sensitive surface  710  in order to prevent or reduce the chance of rotation of the display due to the force of a touch. Similarly, the static breaking torque may be increased based on an adjusted force threshold calculated using, for example, a relationship described above with respect to Equation 4. The static breaking torque may be adjusted using a mechanical or electromechanical joint that includes an adjustable clutch or variable friction coupling. The adjustment of the static breaking torque may occur in addition to an adjustment of the force threshold in accordance with embodiments described herein. 
     Similar to the previous examples, the support stand  720  defines an inherent pivot point  726  along an edge of the interface between the support stand  720  and the support surface. Similar to the examples provided above, a dynamic force threshold may be defined based on an estimated maximum force that will result in tipping and/or sliding of the computing system  700 . 
     While the examples of  FIG. 7  depicts one example linkage having multiple pivots, other embodiments may include alternative arrangements of the pivot points and/or the connecting links. In one example, a support stand may include a mechanical linkage having multiple pivot points and connecting links that are configured to produce a linear motion in response to a force that exceeds a static breaking threshold. Using the techniques and principles described herein, a dynamic threshold may be computed or adjusted based on the estimated static breaking torque of the corresponding pivots that would result in a linear translation of the touch-sensitive surface and associated components of the device. 
       FIG. 8  depicts an example notebook computing system having a hinged display. In this example, the notebook computing system  800  includes a touch-sensitive surface  810  that is configured to detect both a location and a magnitude of force on a display portion of the notebook computing system  800 . As shown in  FIG. 8 , the notebook computing system  800  may include a hinged coupling  822  that is configured to provide a rotational coupling between the upper portion  830  and the lower portion  820  of the notebook computing system  800 . The hinged coupling  822  defines a pivot axis about which the upper portion  830  may rotate if a torque is applied that exceeds the static limits. 
     Similar to the previous examples, the hinged coupling  822  may be configured to be locked or fixed when not being adjusted. In some cases, the hinged coupling  822  may include a mechanical clutch or engagement that prevents movement if a static torque is not exceeded. In accordance with some embodiments, the force threshold of the notebook computing system  800  may be dynamically adjusted to reduce the chance that the static torque of the hinged coupling  822  will be exceeded. The dynamic threshold may be computed using a relationship similar to the one described in Equation 4 with respect to  FIG. 6 , above. Also similar to the previous examples, the force threshold of the notebook computing system  800  may be adjusted based on an estimated friction between the lower portion  820  and the supporting surface. 
     Similar to the example provided above with respect to  FIGS. 6 and 7 , the static breaking torque of the hinged coupling  822  of  FIG. 8  may be dynamically adjusted or varied in response to a touch on the touch-sensitive surface. For example, the static breaking torque may be increased in response to a touch near the edge of the touch-sensitive surface  810  in order to prevent or reduce the chance of rotation of the display due to the force of a touch. The static breaking torque may be adjusted using a mechanical or electromechanical joint that includes an adjustable clutch or variable friction coupling. 
     The adjustment of the static breaking torque may occur in addition to and/or in response to an adjustment of the force threshold in accordance with embodiments described herein. For example, the static breaking torque may be adjusted (e.g., increased) in response or in accordance with an adjusted force threshold. Using a relationship similar to the one described above with respect to Equation 4, an adjusted force threshold may be computed using a nominal or baseline breaking torque value. The actual static breaking torque of the hinged coupling  822  may then be increased to provide a more rigid support to further reduce the probability that the upper portion  830  will move in response to touch interaction with the touch-sensitive surface  810 . 
       FIGS. 9-11  depict an example tablet computing system having multiple sub-regions defined over a touch-sensitive surface. In accordance with some embodiments, multiple sub-regions may be defined over a touch-sensitive surface, and a respective region-specific threshold may be assigned to or defined for each sub-region. 
       FIG. 9  depicts an example device  900  having multiple sub-regions defined with respect to pivot  920 . The example depicted in  FIG. 9  may represent a mounting configuration similar to the support stand configurations of  FIGS. 3, 4, and 5 . That is, the device  900  may be supported in an upright or inclined position using a stand that may define a pivot  920  about which the device  900  will rotate if the static torque is exceeded. To reduce the chance that touch interactions with the touch-sensitive surface  910  will result in tipping or undesirable movement of the device  900 , multiple region specific regions, each having a region-specific threshold, may be defined over the touch-sensitive surface  910 . 
     As shown in  FIG. 9 , four sub-regions  931 ,  932 ,  933 , and  934  are defined along the length of the touch-sensitive surface  910 . To reduce the chance of undesirable movement while also providing an optimized or maximized force response, a dynamic region-specific force threshold may be defined or assigned to each respective sub-region. In general, the region-specific force thresholds may decrease as the distance from the pivot axis  920  is increased. For example, the force threshold of sub-region  934  may be less than the force threshold of sub-region  933 , which in turn has a force threshold that is less than the force threshold of sub-region  932 . Sub-region  931  may have the largest or greatest force threshold as compared to the set of sub-regions  932 ,  933 , and  934 . The region-specific force thresholds may be computed or determined in accordance with the relationship described above with respect to Equation 2.  FIG. 9  depicts one example implementation having an arbitrary size, shape, and number. These and other aspects of the sub-regions may vary in different embodiments. 
     In some embodiments, the device  900  is configured to redefine the sub-regions  931 - 934  in response to a change in orientation. For example, if the device  900  is rotated 90 degrees into a support configuration such that the pivot axis  920  is parallel to the long sides or length of the device  900 , the sub-regions and the corresponding dynamic thresholds may be redefined accordingly. In particular, each of the sub-regions may be defined along the length of the device  900  (as opposed to along the width as shown in  FIG. 9 ). Similar to as described above, those sub-regions that are further from the pivot axis  920  may have a reduced dynamic threshold as compared to those sub-regions that are closer to the pivot axis  920 . The number of sub-regions may be reduced or changed to accommodate the aspect ratio of the touch-sensitive surface  910  or accommodate other geometric constraints. 
       FIGS. 10 and 11  depict alternative configurations having multiple sub-regions defined over the touch-sensitive surface  910 . The configurations of  FIGS. 10 and 11  may be consistent with a support configuration that defines a two-dimensional pivot  922  at or near the center of the touch-sensitive surface  910 . Such a support configuration may be consistent with the ball-joint pivot configuration described above with respect to  FIG. 7 . In this configuration, the device  900  may rotate side-to-side as well as up and down to accommodate a viewing angle or otherwise present the touch-sensitive surface in a preferred orientation with respect to the user. 
     As shown in  FIG. 10 , multiple ring-shaped sub-regions  941 ,  942 ,  943 , and  944  may be defined and a region-specific threshold may be assigned to or defined for each respective sub-region. In general, the region-specific thresholds may be reduced as the distance from the pivot  922  is increased. In particular, the sub-region  941  may have the greatest force threshold because it is located at or near the pivot  922 . Each surrounding sub-region  942 ,  943 , and  944  may have a progressively decreasing dynamic threshold as each region is further from the pivot  922 . 
       FIG. 11  depicts an alternative sub-region definition. Instead of concentric or expanded sets of ring-shaped sub-regions, multiple nested sub-regions  951 ,  952 , and  953  may be defined over the touch-sensitive surface  910 . Similar to the previous examples, the sub-regions that are located closer to the pivot  922  may have a dynamic force threshold that is greater than those sub-regions that are further from the pivot  922 . Accordingly, sub-region  951 , which includes the pivot  922  may have the largest dynamic threshold, while the dynamic region-specific thresholds associated with surrounding regions  952  and  953  may be progressively reduced. 
     The dynamic region-specific thresholds may be computed or estimated based on an estimated static condition. In particular, if the pivot  922  has a static torque, the dynamic region-specific thresholds may be computed in accordance with the relationship described above with respect to Equation 4. 
       FIG. 12  depicts an example process  1200  for dynamically adjusting a force threshold of an electronic device. The process  1200  may be implemented on any of the example devices discussed above with respect to  FIGS. 1-11  or below with respect to  FIG. 13 . The following process  1200  may be used to dynamically adjust a force threshold for a touch-sensitive surface or touch-sensitive button and implemented using, for example, the processing unit and other hardware elements described with respect to  FIG. 13  or other embodiments described herein. The process  1200  may be implemented as processor-executable instructions that are stored within the memory of the electronic device. 
     In operation  1202 , a stability condition is estimated or determined. The stability condition may correspond to a particular support or mounting configuration of the device. In some examples, the device is configured to use one or more internal sensors, user inputs, or electrical signals from an external device to determine or estimate how the device is currently being supported or mounted. In one example, operation  1202  may determine that the device is either hand-held or being supported by a stationary object. Operation  1202  may further determine the orientation of the device and/or position of the device. In general, operation  1202  may be used to estimate the susceptibility of the device to slipping, tipping, or otherwise being adversely affected by a forceful touch on a touch-sensitive surface, such as a touch screen or touch sensor. 
     In one example embodiment of operation  1202 , the device may be configured to determine that the device is being supported by a support accessory, such as a stand or mount. The determination may be made based on a sensed position of the device and/or a sustained period of non-movement that is consistent with the device being supported by a particular support accessory. In particular, the orientation of the device may be determined using one or more sensors including, without limitation, an accelerometer, an inclinometer, a gyrometer, a magnetometer, and so on. The determination may also be made based on a sustained or measured period of non-movement in which the orientation of the device does not significantly change. 
     In another example embodiment of operation  1202 , the device may be configured to determine that the device is being supported by a particular component based on an electrical or coupling or sensed proximity of the component to the device. In some embodiments, the device includes a proximity sensor that is configured to detect the presence of a support accessory, such as a stand or mount. The proximity sensor may also be configured to identify the type of support accessory that is attached using, for example, magnetic coding or other electromagnetic sensing technique. Additionally or alternatively, the device may be configured to electrically couple to a support accessory having a processing unit or other electronic components. In some embodiments, the support accessory may be characterized as an electronic device and may include one or more components of an electronic device, as described below with respect to  FIG. 13 . A support accessory that includes one or more electronic components, particularly some form of processing unit, may be referred to as an electronic stand. An electrical signal received from the support accessory (e.g., an electronic stand) may be used to make the determination of operation  1202 . 
     In another example embodiment of operation  1202 , the device may be configured to determine that the device is being held or supported by the user. If the device is a tablet device, mobile telephone, portable media player or other hand-held device, the determination may be made based on an orientation and/or a sensed movement of the device that is consistent with a hand-held scenario. If the device is a wearable electronic device, such as a smart watch, health monitoring device, or other similar device, the determination may be made based on a detected coupling to or with a body part of the user. In some cases, the device may be configured to detect the proximity or presence of the user using a capacitive, inductive, optical, or other similar measurement. In some cases, the device may be configured to detect moisture, such as perspiration, which may indicate that the hand-held support is slippery or less stable than normal. 
     In another example embodiment of operation  1202 , the device may be configured to detect an unstable mounting or support configuration. Using one or more internal sensors, the device may be configured to detect movement of the device that is consistent with the device tipping, sliding, or slipping in response to interaction with the touch-sensitive surface. For example, the device may use an accelerometer, an inclinometer, a gyrometer, or other similar sensor to detect momentary rotation that is consistent with a tipping or rocking motion of the device due to a user pressing on the touch-sensitive surface. In another example, the device may use a position sensor to determine that the device is sliding or slipping across a support surface. The device may also be configured to use a microphone, camera or other sensor to detect changes in the environmental conditions that are consistent with a sliding or slipping scenario. 
     In operation  1204 , a force threshold is determined based on the estimated stability condition. In particular, the device may be configured to determine a force threshold that is less likely to cause undesirable movement of the device due to normal or predicable interaction with a touch-sensitive surface. Normal or predictable interaction may correspond to, for example, touch- and force-based input that can be sensed by the touch-sensitive surface within the operational parameters of the device. With respect to the embodiments described above, the device may determine a dynamic threshold based on the relationships illustrated above with respect Equations 1-4 discussed above. In particular, the dynamic threshold may be determined based on a likelihood that the device will tip in response to a forceful touch on the touch-sensitive surface using the determination of operation  1202 , above. The dynamic threshold may also be determined based on a likelihood that the device will slip or slide across a supporting surface, within the user&#39;s hands, or slide about the user&#39;s body, depending on the estimated stability condition. 
     In some embodiments, two or more types of thresholds are determined and used to define the dynamic threshold. For example, both a tipping threshold and a sliding or slipping threshold may be determined based on the support configuration. The tipping threshold may be determined in accordance with, for example, the relationships illustrated in Equations 1 and 2 described above. A sliding threshold may be determined in accordance with, for example, the relationship illustrated in Equation 3 described above. Additionally or alternatively, a pivot-slipping threshold that estimates the movement of a mechanical joint or connection may be determined in accordance with, for example, the relationship illustrated in Equation 4, described above. The device may be configured to select the lowest threshold of two or more threshold types when determining the dynamic threshold of the device. Alternatively, the device may be configured to compute a composite dynamic threshold that accounts for a dominating effect due to a touch. For example, if a device is mounted on a stand as depicted in  FIG. 3 , a touch lower on the touch-sensitive surface  110  may be more likely to result in a slide and, thus, the sliding threshold may dominate. A touch higher on the touch-sensitive surface  110  may be more likely to result in a tipping of the device  100  and, thus the tipping threshold may dominate. In some cases, the device is configured to compute a transition between, a tipping threshold, a slipping threshold, a pivot-slipping threshold, or other type of threshold in order to determine which threshold to apply to the dynamic threshold. 
     With respect to operation  1204 , the force threshold of the device and/or an associated accessory may be determined or defined. In particular, the dynamic force threshold may be applied to a force sensor that is operatively coupled or integrated with the touch-sensitive surface of the device. Additionally or alternatively, the dynamic force threshold may be applied to an accessory, such as a stylus or pen, having a force sensor that is configured to measure a force applied to the device. 
     The force threshold may vary across the surface of the device. As described with respect to  FIGS. 9-11 , multiple sub-regions may be defined over the surface of the device. Accordingly, the force threshold may vary along one direction or two directions, depending on the support configuration. A one-dimensional variation in the force threshold may be appropriate for support configurations that define a single pivot axis while a two-dimensional variation may be appropriate for support configurations that define a multi-axis or ball-joint pivot. While the examples of  FIGS. 9-11  depict a region-specific threshold that varies by an area or sub-region, the threshold may vary continuously along the touch-sensitive surface. Hence, the resolution at which the threshold may be varied may correspond to the resolution of the location that can be determined using the touch sensor of the device. The threshold may vary in a linear or a non-linear fashion across the touch-sensitive surface depending on the embodiment. 
     With respect to operation  1204 , the dynamic threshold may be configured to vary over time or may be subject to periodic calibration. For example, the dynamic threshold may be adjusted over time over the life of the device to account for changes in a structural joint or pivot, which may become more loose or easier to move with repeated use. The dynamic threshold may also be adjusted to account for changes in temperature or other environmental conditions that may also affect the likelihood that the device will tip or slide in response to user input. A periodic calibration may be used to test the stability of the device, and the dynamic threshold may be adjusted accordingly. For example, the threshold may be increased until an unstable condition is detected, and then the dynamic threshold may be set to a new calibrated value based on the measured stability or rigidity of the support. 
     In some embodiments, the dynamic threshold may be user specific. For example, the device may be configured to identify the user using sensors and/or manual user input. The device may then adjust the dynamic threshold based on the preferences or settings associated with that particular user. The settings may allow for further adjustment of the dynamic threshold within a range or in accordance with the preferences set for the specific user. 
     In general, operations  1202  and  1204  may be performed on regular intervals to adjust the dynamic force threshold to match changing support configurations. For example, the device may be configured to detect a change in the support configuration determined in operation  1202 . In response to a change in the support configuration, the device may be configured to determine one or more new dynamic thresholds. In some cases, the sub-regions or other scheme for varying the threshold over the touch-sensitive surface of the device is updated in response to a change in the support configuration. By way of specific example, a set of region-specific thresholds and a sub-region definition may be updated when a device is rotated from use in a portrait to a landscape orientation. 
     In operation  1206 , a force-event or press-event signal is initiated or triggered based on a touch that exceeds the threshold defined in operation  1204 . As previously described, a press-event signal may be used as a user input to control an aspect of the device. For example, the dynamic threshold may define which user touch interactions are recognized as a force touch and which interactions are simply a touch. The distinction may allow the device to recognize a user selection of a displayed object or invoke some other action due to a forceful touch. In some cases, the dynamic threshold is used to distinguish a gesture user input from an accidental or incidental touch on the surface of the device. In some embodiments, multiple dynamic thresholds may be defined, each threshold associated with a different level of functionality. 
     In some embodiments, the dynamic threshold is used to adjust a scale or range of continuous force input that is recognized by the device. For example, the force sensor may be used to produce an analog or substantially continuous output that corresponds to a variable force exerted on the device. The analog or substantially continuous output may be used to adjust the volume of the device, brightness of the screen, or control some other continuously variable aspect of the device or a software application. The dynamic threshold may be used to scale the output that is recognized by the device to reduce the risk that the touch interaction will result in undesirable movement of the device. 
     In some embodiments, the dynamic threshold is used to adjust a trigger or actuation point for a virtual or software-driven button defined over the touch-sensitive surface. In some cases, the touch-sensitive surface is defined over a display that is configured to display user-selectable objects, such as buttons or other controls. In other cases, the touch-sensitive surface is defined over a region of the device associated with a dedicated button or user input. For example, the dynamic threshold defined in operation  1204  may be used to determine the actuation sensitivity of a home button or other dedicated user-control surface on the device. 
     The operations of process  1200  may be performed in a continuous fashion during the operation and use of a touch-sensitive surface. In some embodiments, process  1200  is performed automatically when the touch-sensitive surface of the device is in use. Alternatively, the process  1200  may be triggered by a user-input or some other initiating event. The operations of process  1200  are merely illustrative in nature and are not intended to be limiting. 
       FIG. 13  depicts example components of an electronic device in accordance with the embodiments described herein. The schematic representation depicted in  FIG. 13  may correspond to components of the devices depicted in  FIGS. 1-11 , described above However,  FIG. 13  may also more generally represent other types of devices that include any device configured to receive force-input in accordance with the embodiments described herein. 
     As shown in  FIG. 13 , a device  1300  includes a processing unit  1302  operatively connected to computer memory  1304  and computer-readable media  1306 . The processing unit  1302  may be operatively connected to the memory  1304  and computer-readable media  1306  components via an electronic bus or bridge. The processing unit  1302  may include one or more computer processors or microcontrollers that are configured to perform operations in response to computer-readable instructions. The processing unit  1302  may include the central processing unit (CPU) of the device. Additionally or alternatively, the processing unit  1302  may include other processors within the device including application specific integrated chips (ASIC) and other microcontroller devices. The processing unit  1302  may be configured to perform functionality described in the examples above, including, without limitation, the operations of process  1200  described above with respect to  FIG. 12 . 
     The memory  1304  may include a variety of types of non-transitory computer-readable storage media, including, for example, read access memory (RAM), read-only memory (ROM), erasable programmable memory (e.g., EPROM and EEPROM), or flash memory. The memory  1304  is configured to store computer-readable instructions, sensor values, and other persistent software elements. Computer-readable media  1306  also includes a variety of types of non-transitory computer-readable storage media including, for example, a hard-drive storage device, a solid state storage device, a portable magnetic storage device, or other similar device. The computer-readable media  1306  may also be configured to store computer-readable instructions, sensor values, and other persistent software elements. 
     In this example, the processing unit  1302  is operable to read computer-readable instructions stored on the memory  1304  and/or computer-readable media  1306 . The computer-readable instructions may adapt the processing unit  1302  to perform the operations or functions described above with respect to  FIGS. 1-11  or below with respect to the example process  FIG. 13 . In particular, the processing unit  1302 , the memory  1304 , and/or the computer-readable media  1306  may be configured to implement a dynamic force threshold for one or more touch-sensitive surfaces of the device  1300 . The computer-readable instructions may be provided as a computer-program product, software application, or the like. 
     As shown in  FIG. 13 , the device  1300  also includes a display  1308 . The display  1308  may include a liquid-crystal display (LCD), organic light emitting diode (OLED) display, light emitting diode (LED) display, or the like. If the display  1308  is an LCD, the display may also include a backlight component that can be controlled to provide variable levels of display brightness. If the display  1308  is an OLED or LED type display, the brightness of the display  1308  may be controlled by modifying the electrical signals that are provided to display elements. 
     The device  1300  may also include a battery  1309  that is configured to provide electrical power to the components of the device  1300 . The battery may include one or more power storage cells that are linked together to provide an internal supply of electrical power. The battery  1309  may be operatively coupled to power management circuitry that is configured to provide appropriate voltage and power levels for individual components or groups of components within the device  1300 . The battery  1309 , via power management circuitry, may be configured to receive power from an external source, such as an AC power outlet. The battery  1309  may store received power so that the device  1300  may operate without connection to an external power source for an extended period of time, which may range from several hours to several days. 
     In some embodiments, the device  1300  includes one or more input devices  1310 . The input device  1310  is a device that is configured to receive user input. The input device  1310  may include, for example, a push button, a touch-activated button, a keyboard, a key pad, or the like. In some embodiments, the input device  1310  may provide a dedicated or primary function, including, for example, a power button, volume buttons, home buttons, scroll wheels, and camera buttons. Generally, a touch screen or touch-sensor may also be classified as an input device. However, for purposes of this illustrative example, the touch sensor  1320  and force sensor  1322  are depicted as distinct components within the device  1300 . 
     The device  1300  may also include a touch sensor  1320  that is configured to determine a location of a touch over a touch-sensitive surface of the device  1300 . The touch sensor  1320  may include a capacitive array of electrodes or nodes that operate in accordance with a mutual-capacitance or self-capacitance scheme. The touch sensor  1320  may be integrated with one or more layers of a display stack (e.g., one or more cover sheets) to form a touch screen similar to the example described above with respect to  FIG. 2 . The touch sensor  1320  may also be integrated with another component that forms an external surface of the device  1300  to define a touch-sensitive surface. 
     The device  1300  may also include a force sensor  1322  that is configured to receive force touch input over a touch-sensitive surface of the device  1300 . The force sensor  1322  may include one or more layers that are sensitive to strain or pressure applied to an external surface of the device. In particular, the force sensor  1322  may be integrated with one or more layers of a display stack similar to the example described above with respect to  FIG. 2 . In accordance with the embodiments described herein, the force sensor  1322  may be configured to operate using a dynamic or adjustable force threshold. The dynamic or adjustable force threshold may be implemented using the processing unit  1302  and/or circuitry associated with or dedicated to the operation of the force sensor  1322 . 
     The device  1300  may also include one or more sensors  1324  that may be used to detect an environmental condition, orientation, position, or some other aspect of the device  1300 . Example sensors  1324  that may be included in the device  1300  include, without limitation, one or more accelerometers, gyrometers, inclinometers, goniometers, or magnetometers. The sensors  1324  may also include one or more proximity sensors, such as a magnetic hall-effect sensor, inductive sensor, capacitive sensor, continuity sensor, and the like. The proximity sensor(s) may be configured to detect the presence of a support structure or support surface and used to determine a support configuration in accordance with some embodiments. 
     The sensors  1324  may also be broadly defined to include wireless positioning devices including, without limitation, global positioning system (GPS) circuitry, Wi-Fi circuitry, cellular communication circuitry, and the like. The device  1300  may also include one or more optical sensors including, without limitation, photodetectors, photosensors, image sensors, infrared sensors, and the like. While the camera  1326  is depicted as a separate element in  FIG. 13 , a broad definition of sensors  1324  may also include the camera  1326  with or without an accompanying light source or flash. The sensors  1324  may also include one or more acoustic elements, such as a microphone used alone or in combination with a speaker element. The sensors may also include a temperature sensor, barometer, pressure sensor, altimeter, moisture sensor or other similar environmental sensor. 
     The sensors  1324 , either alone or in combination, may generally be configured to determine an orientation, position, and/or movement of the device  1300 . The sensors  1324  may also be configured to determine one or more environmental conditions, such as a temperature, air pressure, humidity, and so on. The sensors  1324 , either alone or in combination with other input, may be configured to estimate a property of a supporting surface including, without limitation, a material property, surface property, friction property, or the like. Output from one or more of the sensors  1324  may be used to determine a support or mounting configuration and/or used to determine a dynamic force threshold for the device  1300 . 
     The device  1300  may also include a camera  1326  that is configured to capture a digital image or other optical data. The camera  1326  may include a charge-coupled device, complementary metal oxide (CMOS) device, or other device configured to convert light into electrical signals. The camera  1326  may also include one or more light sources, such as a strobe, flash, or other light-emitting device. As discussed above, the camera  1326  may be generally categorized as a sensor for detecting optical conditions and/or objects in the proximity of the device  1300 . However, the camera  1326  may also be used to create photorealistic images that may be stored in an electronic format, such as JPG, GIF, TIFF, PNG, raw image file, or other similar file types. 
     The device  1300  may also include a communication port  1328  that is configured to transmit and/or receive signals or electrical communication from an external or separate device. The communication port  1328  may be configured to couple to an external device via a cable, adaptor, or other type of electrical connector. In some embodiments, the communication port  1328  may be used to couple the device  1300  to an accessory, such as a smart case, smart cover, smart stand, keyboard, or other device configured to send and/or receive electrical signals. The communication port  1328  may be configured to receive identifying information from an external accessory, which may be used to determine a mounting or support configuration. For example, the communication port  1328  may be used to determine that the device  1300  is coupled to a support accessory, such as particular type of stand or support structure. In accordance with some embodiments, this determination may be used to define a dynamic force threshold for the device  1300 . 
     The foregoing description, for purposes of explanation, uses 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: 20160229
Publication Date: 20190115
Grant Date: 20190115
Priority Date: 20160229
Inventors: HILL, MATTHEW D.
PHOUTHAVONG, RASAMY
MYERS, SCOTT A.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1694", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04186", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/04886", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/04186", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04886", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1694", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1694", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 59678936