PATENT DOCUMENT

Publication Number: US-11460946-B2
Application Number: US-202117360970-A
Country: US
Kind Code: B2

Title: Electronic device having a touch sensor, force sensor, and haptic actuator in an integrated module

Abstract:
An electronic device includes an input device. The input device has an input/output module below or within a cover defining an input surface. The input/output module detects touch and/or force inputs on the input surface, and provides haptic feedback to the cover. In some instances, a haptic device is integrally formed with a wall or structural element of a housing or enclosure of the electronic device.

Claims:
What is claimed is: 
     
       1. A portable electronic device comprising:
 an enclosure having a wall formed from a ceramic material, the wall defining an exterior surface of the portable electronic device and an interior surface opposite the exterior surface; 
 a light-transmissive cover coupled to the enclosure; 
 a touch-sensitive display below the light-transmissive cover and configured to detect first touch inputs applied to the light-transmissive cover; and 
 a touch sensing system configured to detect a second touch input applied to an exterior surface of the wall and comprising:
 an input electrode embedded at least partially within the ceramic material of the wall and extending below the interior surface of the wall; and 
 processing circuitry operably coupled to the input electrode and configured to detect the second touch input applied to the exterior surface of the wall based on an electrical response of the input electrode to the second touch input. 
 
 
     
     
       2. The portable electronic device of  claim 1 , wherein:
 the portable electronic device is a mobile phone; 
 the light-transmissive cover defines a front side of the mobile phone; 
 the enclosure defines a back side of the mobile phone opposite the front side of the mobile phone; and 
 the wall defines a peripheral side of the mobile phone. 
 
     
     
       3. The portable electronic device of  claim 1 , wherein the processing circuitry is configured to:
 drive the input electrode with a first electrical signal during a first period of time; and 
 drive the input electrode with a second electrical signal during a second period of time. 
 
     
     
       4. The portable electronic device of  claim 3 , wherein the first period of time and the second period of time are non-overlapping periods of time. 
     
     
       5. The portable electronic device of  claim 1 , further comprising a haptic actuator at least partially embedded in the ceramic material of the wall. 
     
     
       6. The portable electronic device of  claim 5 , wherein:
 the ceramic material is a first ceramic material; 
 the haptic actuator comprises a ceramic piezoelectric element; 
 the ceramic piezoelectric element comprises a second ceramic material; and 
 the second ceramic material of the ceramic piezoelectric element is at least partially sintered to the first ceramic material of the wall. 
 
     
     
       7. The portable electronic device of  claim 5 , wherein the processing circuitry is configured to:
 detect an amount of force of the second touch input based on a resistive response of the input electrode, the resistive response resulting from a deformation of the input electrode; and 
 cause the haptic actuator to produce a localized deflection of the wall in response to at least one of the detected second touch input or the detected amount of force. 
 
     
     
       8. The portable electronic device of  claim 1 , further comprising an array of input electrodes, wherein:
 the array of input electrodes comprises the input electrode; and 
 the array of input electrodes is configured to detect a location of the second touch input along the exterior surface of the wall. 
 
     
     
       9. An electronic device, comprising:
 an enclosure having a ceramic wall defining at least a portion of an exterior surface of the electronic device; 
 a display positioned at least partially within the enclosure; 
 a first electrode integrally formed with the ceramic wall, the first electrode at least partially embedded into the ceramic wall below an interior surface of the ceramic wall; 
 a second electrode integrally formed with the ceramic wall, the second electrode at least partially embedded into the ceramic wall below the interior surface of the ceramic wall; and 
 processing circuitry operably coupled to the first electrode and the second electrode and configured to detect, through the ceramic wall, a touch input applied to the at least the portion of the exterior surface of the electronic device based on an electrical response of at least one of the first electrode or the second electrode to the touch input. 
 
     
     
       10. The electronic device of  claim 9 , wherein the processing circuitry is further configured to detect the touch input based on a capacitive response of the first and second electrodes. 
     
     
       11. The electronic device of  claim 9 , wherein the processing circuitry is further configured to detect an amount of force of the touch input based on a resistive response of at least one of the first electrode and the second electrode. 
     
     
       12. The electronic device of  claim 11 , wherein the resistive response results from a deformation of the first electrode or the second electrode. 
     
     
       13. The electronic device of  claim 12 , further comprising a haptic actuator integrally formed with the ceramic wall, wherein the processing circuitry is further configured to cause the haptic actuator to produce a localized deflection of the ceramic wall in response to at least one of the detected touch input or the detected amount of force. 
     
     
       14. The electronic device of  claim 13 , wherein:
 the haptic actuator comprises a piezoelectric element; 
 the piezoelectric element contracts along a first direction; and 
 the contraction along the first direction causes the localized deflection of the exterior surface of the electronic device. 
 
     
     
       15. The electronic device of  claim 9 , wherein the first electrode at least partially surrounds the second electrode. 
     
     
       16. A portable electronic device comprising:
 a housing defining a wall comprising a ceramic material; 
 a display positioned at least partially within the housing; 
 a touch sensing system configured to detect a touch input applied to an exterior portion of the wall; 
 a piezoelectric element fused to the ceramic material and embedded at least partially within the wall and extending below an interior surface of the wall and configured to produce a localized deflection of the exterior portion of the wall in response to the touch input. 
 
     
     
       17. The portable electronic device of  claim 16 , wherein:
 the touch sensing system comprises one or more electrodes; and 
 the touch sensing system is configured to:
 detect an amount of force of the touch input based on a resistive response of least one of the one or more electrodes; and 
 cause the piezoelectric element to produce the localized deflection in response to at the detected amount of force. 
 
 
     
     
       18. The portable electronic device of  claim 17 , wherein an electrode of the one or more electrodes is formed from a piezoresistive material having a spiral pattern. 
     
     
       19. The portable electronic device of  claim 16 , wherein:
 the ceramic material is a first ceramic material; 
 the piezoelectric element comprises a second ceramic material; and 
 the piezoelectric element is integrally formed with the one or more walls by co-firing the first ceramic material with the second ceramic material. 
 
     
     
       20. The portable electronic device  claim 16 , wherein the piezoelectric element is sintered to the ceramic material of the one or more walls.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/102,557, filed Aug. 13, 2018, which is a non-provisional patent application of and claims the benefit of U.S. Provisional Patent Application No. 62/555,019, filed Sep. 6, 2017, the disclosures of which are hereby incorporated herein by reference in their entirety. 
    
    
     FIELD 
     The described embodiments relate generally to input devices in electronic devices. More particularly, the present embodiments relate to an input/output module that receives touch and/or force inputs and provides localized deflection along an input surface of an electronic device. 
     BACKGROUND 
     Electronic devices are commonplace in today&#39;s society and typically include an input device used to control or provide commands to the electronic device. The input device may include a button, knob, key or other similar device that can be actuated by the user to provide the input. As electronic devices become more compact, it may be difficult to integrate traditional input devices without increasing the size or form factor of the electronic device. Additionally, many traditional input devices are not configurable, which may limit the adaptability of the electronic device. 
     Systems and techniques described herein are directed to an electronic device having an integrated module that includes a touch sensor, a force sensor, and a haptic actuator that may form an input device or input surface for an electronic device. 
     SUMMARY 
     Embodiments described herein relate to an electronic device that includes an input/output module for receiving touch and/or force inputs, and to provide localized haptic feedback. In some embodiments, the electronic device includes an input surface and the input/output module receives input on the input surface and provides haptic feedback to the same input surface. 
     In an example embodiment, an electronic device includes a cover defining an input surface and an input/output module below the cover. The input/output module includes a substrate. A drive input electrode is coupled to the substrate, and a sense input electrode is coupled to the substrate adjacent the drive input sensor. A piezoelectric element is coupled to the substrate and configured to cause a deflection of the cover in response to an actuation signal. 
     The electronic device also includes a processing circuit operably coupled to the drive input electrode and the sense input electrode. The processing circuit is configured to detect a touch on the input surface based on a change in capacitance between the drive input electrode and the sense input electrode. The processing circuit is further configured to detect an amount of force of the touch based on a change in resistance of the drive input electrode or the sense input electrode. The processing circuit is also configured to cause the actuation signal in response to at least one of the detected touch or the detected amount of force. 
     In some cases, in response to the actuation signal, the piezoelectric element contracts along a first direction. The contraction along the first direction causes the deflection in the cover along a second direction that is transverse to the first direction. The drive input electrode and the sense input electrode may be formed from a piezoresistive material deposited on the substrate in a spiral pattern. The touch may form a touch capacitance between a touching object and the sense and drive input electrodes, and the touch capacitance may cause the change in capacitance between the drive input electrode and the sense input electrode. 
     Another example embodiment may include a method of determining a location and an amount of force corresponding to a touch on an input surface of an electronic device. The method includes the operations of driving a first set of input electrodes, disposed on a surface of a substrate, with a drive signal and monitoring a second set of input electrodes, distinct from the first set of input sensors and disposed on the surface of the substrate, for a capacitive response to the drive signal and the touch. 
     The method further includes determining the location corresponding to the touch based on the capacitive response, monitoring the first set of input electrodes for a resistive response to the drive signal and the touch, and determining the amount of force corresponding to the touch based on the resistive response. 
     In some cases, the monitoring the second set of input sensors for the capacitive response and the monitoring the first set of input sensors for the resistive response occur during time periods which at least partially overlap. In other cases, the monitoring the second set of input sensors for the capacitive response occurs during a first period of time and the monitoring the first set of input sensors for the resistive response occurs during a second, non-overlapping period of time. 
     In still another example embodiment, an input device includes a cover defining an input surface external to the input device and a substrate coupled to the cover. The substrate includes a top surface facing the cover and a bottom surface. A drive input electrode is coupled to the top surface, and a sense input electrode is coupled to the top surface adjacent the drive input electrode. The input device also includes a piezoelectric element coupled to the bottom surface and configured to cause a deflection of the cover in response to an actuation signal. A processing circuit is operably coupled to the drive input electrode and the sense input electrode and configured to detect a location of a touch on the input surface and an amount of force corresponding to the touch. 
     In some cases, a conductive layer is deposited on the bottom surface and the piezoelectric element is coupled to a bottom of the conductive layer. The conductive layer may include an array of conductive pads, and the piezoelectric element may be electrically coupled to two conductive pads. The piezoelectric element may be coupled to the array of conductive pads by an anisotropic conductive film. 
    
    
     
       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 elements. 
         FIG. 1  depicts an electronic device with an input device having an integrated input/output module according to the present disclosure. 
         FIG. 2A  depicts an example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating detection of a touch. 
         FIG. 2B  depicts an example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating detection of a force. 
         FIG. 2C  depicts an example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a haptic output. 
         FIG. 3A  depicts a top view of an input device illustrating an example touch and/or force-sensing input electrode. 
         FIG. 3B  depicts a cross-sectional view of the input device depicted in  FIG. 3A , illustrating detection of a touch location by self-capacitance. 
         FIG. 3C  depicts a cross-sectional view of the input device depicted in  FIG. 3A , illustrating detection of an amount of force. 
         FIG. 4A  depicts a top view of an input device illustrating an example pair of touch and/or force-sensing input electrodes. 
         FIG. 4B  depicts a cross-sectional view of the input device depicted in  FIG. 4A , illustrating detection of a touch location by mutual capacitance. 
         FIG. 4C  depicts a cross-sectional view of the input device depicted in  FIG. 4A , illustrating detection of an amount of force. 
         FIG. 5A  depicts an example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a first example input/output module. 
         FIG. 5B  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a second example input/output module. 
         FIG. 5C  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a third example input/output module. 
         FIG. 5D  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a fourth example input/output module. 
         FIG. 5E  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a fifth example input/output module. 
         FIG. 5F  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a sixth example input/output module. 
         FIG. 6A  depicts an example cross-sectional view of an input/output module illustrating the deposition of input electrodes on a top surface of a substrate and haptic actuators on a bottom surface of the substrate. 
         FIG. 6B  depicts an example top view of input electrodes deposited on the top surface of the substrate. 
         FIG. 6C  depicts an example bottom view of a conducting layer for haptic actuators, deposited on the bottom surface of the substrate. 
         FIG. 7A  depicts an example perspective view of a pair of input electrodes disposed adjacent one another over a substrate. 
         FIG. 7B  depicts another example perspective view of a pair of input electrodes disposed above and below one another. 
         FIG. 8A  depicts another electronic device with an input region having an integrated input/output module according to the present disclosure. 
         FIG. 8B  depicts an example cross-sectional view of the electronic device depicted in  FIG. 8A , taken along section B-B, illustrating a first example input/output module. 
         FIG. 8C  depicts another example cross-sectional view of the electronic device depicted in  FIG. 8A , taken along section B-B, illustrating a second example input/output module. 
         FIG. 9  depicts an enclosure for an electronic device having an input/output module disposed at least partially within a portion of the enclosure. 
         FIG. 10A  depicts an example partial cross-sectional view of the electronic device depicted in  FIG. 9 , taken along section C-C. 
         FIG. 10B  depicts an example view of input electrodes deposited on an interior surface of a wall, taken through section D-D of  FIG. 10A . 
         FIG. 10C  depicts another example partial cross-sectional view of the electronic device depicted in  FIG. 9 , taken along section C-C. 
         FIG. 10D  depicts an example partial cross-sectional view showing example patterns of input electrodes. 
         FIG. 11  depicts an example wearable electronic device that may incorporate an input/output module as described herein. 
         FIG. 12  depicts an example input device that may incorporate an input/output module as described herein. 
         FIG. 13  depicts an example method for detecting a location of a touch and an amount of force corresponding to the touch with a single module. 
         FIG. 14  depicts another example method for detecting a location of a touch and an amount of force corresponding to the touch with a single module. 
         FIG. 15  depicts example components of an electronic device in accordance with the embodiments described herein. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     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 implementation. To the contrary, the described embodiments are intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the disclosure and as defined by the appended claims. 
     The following disclosure relates to an electronic device with an input/output module that receives touch and/or force inputs and provides localized deflection at a surface. An electronic device may include an enclosure component defining an input surface for receiving user inputs and outputting feedback to the user. Example enclosure components include a cover (e.g., a cover sheet, a trackpad cover, and the like), a wall of an enclosure (e.g., a sidewall or other wall), and the like. Example input surfaces include a trackpad, a touch screen, a surface of a wall of a device enclosure, or another exterior surface of an enclosure of an electronic device. Example electronic devices include a personal computer, a notebook or laptop computer, a tablet, a smart phone, a watch, a case for an electronic device, a home automation device, and so on. 
     Sensors may be placed on, within, or below the enclosure component to receive various types of inputs. For example, a touch sensor may detect an object approaching or in contact with the input surface. By including an array of touch sensors, the electronic device may determine the location of the object, and in some cases of multiple objects, relative to the input surface. 
     As another example, a force sensor may detect a force applied to the enclosure component. Based on the output of the force sensor, the electronic device may approximate, measure, or otherwise determine an amount of the force applied to the cover. With an array of force sensors, the electronic device may determine the locations and amounts of multiple forces applied to the cover. 
     The electronic device may also provide haptic output to a user through the enclosure component. Haptic output is generated through the production of mechanical movement, vibrations, and/or force. In some embodiments, the haptic output can be created based on an input command (e.g., one or more touch and/or force inputs), a simulation, an application, or a system state. When the haptic output is applied to the enclosure component, a user can detect or feel the haptic output and perceive the haptic output as localized haptic feedback. The electronic device may include one or more haptic devices configured to provide haptic feedback. 
     In some embodiments, an integrated touch input, force input, and haptic feedback module (an “input/output module”) is provided on, within, or below the enclosure component of an electronic device. In some embodiments, one or more components of the input/output module are integrally formed with the enclosure component. As used herein, “integrally formed with” may be used to refer to defining or forming a unitary structure. For example, one or more input electrodes and/or haptic devices may be integrally formed with an enclosure component, such as a ceramic enclosure of an electronic device. Integrally forming a haptic actuator with an enclosure component (e.g., on or within a wall of an enclosure) allows for localized haptic feedback (e.g., localized deflection of the wall) to be produced at select locations along an exterior surface of the enclosure. Similarly, integrally forming an input electrode within an enclosure component allows for localized touch input and force input detection at select locations along the exterior surface of the enclosure. In some embodiments, localized haptic feedback is produced in response to detecting touch and/or force input along the exterior surface of the enclosure. 
     In various embodiments, one or more components of the input/output module and/or other components of the electronic device may be integrally formed with an enclosure component by co-firing or co-sintering. As used herein, “co-firing” may be used to refer to any process by which one or more components or materials are fired in a kiln or otherwise heated to fuse or sinter the materials at the same time. For the purposes of the following discussion, “co-firing” may be used to refer to a process in which two materials, which are in a green, partially sintered, pre-sintered state are heated or sintered together for some period of time. 
     This input/output module may include one or more input electrodes, which are responsive to both touch and force inputs. That is, an array of input electrodes may be used to determine a location of a touch on the input surface and an amount (and location) of force applied to the cover. In some embodiments, an input electrode may be a strain gauge, having a series of parallel conductive traces, for example over a substrate, on a surface of the cover, or within the cover. The conductive traces may be formed in a variety of patterns, including a spiral pattern. As a strain gauge, the input electrode may exhibit a change in resistance in response to force or strain. In addition, the conductive material may exhibit a change in capacitance in response to the approach of a finger or other object. 
     Accordingly, an array of input electrodes may function as both touch and force sensors in a single layer, detecting a location of a touch on the input surface and an amount of force applied to the cover. In some embodiments, the input electrodes may be deposited on or otherwise attached to a top surface of a substrate, such as a glass or polyimide substrate. In some embodiments, the input electrodes may be deposited on or within, or otherwise attached to the cover. 
     The input/output module may also include one or more haptic actuators deposited on, within, or otherwise attached to a bottom surface of the substrate or the cover. A haptic actuator may provide localized haptic feedback to the cover. In an example embodiment, a haptic actuator may be a piezoelectric haptic actuator, having a piezoelectric element which contracts and/or expands in response to application of a voltage across the piezoelectric element. 
     When the haptic actuator is oriented such that an axis of elongation and/or contraction is parallel to an exterior surface of the cover (e.g., disposed within or on the cover or attached to the bottom surface of the substrate), an actuating signal may cause the piezoelectric element to contract along the axis of elongation and/or contraction (e.g., a first direction parallel to the bottom surface). Because the piezoelectric element is fixed with respect to the cover and/or the substrate, the piezoelectric element may bend and deflect along a second direction transverse to the axis of elongation and/or contraction, which may cause a deflection (e.g., a vertical deflection) of the substrate. The deflection of the substrate may be transferred to the cover. The deflection in the cover may be perceived as haptic feedback by a user through a finger or other body part in contact with the input surface. 
     In certain embodiments, the input/output module is disposed below an opaque cover (e.g., a cover including an opaque layer, such as an ink layer) defining an input surface, such as a trackpad of a laptop. The materials of the input/output module may be optically opaque materials. In other embodiments, the input/output module is disposed below a transparent cover defining an input surface, such as a cover of a cellular telephone or tablet device. In some examples, the input/output module may be placed between the cover and a display, and the input/output module may be formed from optically transparent materials. In other examples, the input/output module may be placed below the display and formed from opaque materials. 
     These and other embodiments are discussed below with reference to  FIGS. 1-11 . 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 electronic device with an input device having an integrated input/output module according to the present disclosure. In some embodiments, as depicted in  FIG. 1 , the electronic device  100  is a portable electronic device, specifically a laptop computer. Other embodiments may incorporate the input/output module into another type of portable electronic device, such as a mobile electronic device (see  FIGS. 8A-8C ). In other examples, an electronic device may include a smart phone, a wearable computing device, a digital music player, an automotive device, a kiosk, a stand-alone touch screen display, a mouse, a keyboard, and other types of electronic devices that are configured to receive touch and/or force inputs as well as provide haptic feedback to a user. 
     The electronic device  100  may include an enclosure  101  housing a keyboard  104  and a display  102 . The electronic device  100  may also include an input device  108 , such as a trackpad. The input device  108  may be positioned along a side of the keyboard  104 . For example, as shown in  FIG. 1 , the keyboard  104  may be positioned between the input device  108  and a connection interface between the enclosure  101  and the display  102 . The input device  108  may include a cover defining an input surface, and an input/output module may be incorporated below the cover. The input/output module may detect touch inputs and force inputs on the input surface, and additionally may provide haptic feedback to the cover. Examples of the input device  108  and the features of the input/output module are further depicted below with respect to  FIGS. 2A-7B, 9, and 10 . 
     The display  102  may function as both an input device and an output device. For example, the display  102  may output images, graphics, text, and the like to a user. The display  102  may also act as a touch input device that detects and measures a location of a touch input on the display  102 , via touch-sensing circuitry. The electronic device  100  may also include one or more force sensors that detect and/or measure an amount of force exerted on the display  102 . 
     The keyboard  104  of the electronic device  100  includes an array of keys or buttons (e.g., movable input components). Each of the keys may correspond to a particular input. The keyboard  104  may also include a frame or key web. The frame may define an aperture through which each key protrudes, such that each of the array of keys is at least partially positioned within the frame and at least partially without the frame. The frame also separates one key from an adjacent key and/or an enclosure of the electronic device  100 . 
     In many cases, the electronic device  100  can also include a processor, memory, power supply and/or battery, network connections, sensors, input/output ports, acoustic components, haptic components, digital and/or analog circuits for performing and/or coordinating tasks of the electronic device  100 , and so on. For simplicity of illustration, the electronic device  100  is depicted in  FIG. 1  without many of these components, each of which may be included, partially and/or entirely, within the enclosure  101 . Examples of such components are described below with respect to  FIG. 11 . 
     While this disclosure is generally described with respect to a trackpad, it should be understood that this is only one example embodiment. An integrated input/output module may be incorporated in other regions of a device to provide different functionality. For example, the input/output module may extend over a keyboard region of the electronic device  100  (e.g., in place of all or a portion of the keyboard  104 ) and may be used to define a virtual or soft keyboard. The input/output module may allow for an adaptable key arrangement and may include configurable or adaptable glyphs and markings to designate the location of an array of virtual or configurable key regions. 
     In another example, the input/output module forms an input surface over the display. This may enable a touch- and force-sensitive touch screen providing localized haptic output. The input/output module may be incorporated in a similar manner as described below with respect to  FIGS. 8A-8C . 
     In still another example, the input/output module may form a portion of a key region, such as a function row above a physical keyboard. The input/output module may define a set of dynamically adjustable input regions. A display or other means may provide a visual representation (e.g., through adaptable glyphs and markings) to designate the location of virtual keys or input regions defined by the input/output module. 
     In still another example, the input/output module may be located on or within a portion of a device enclosure, such as a wall of a device enclosure, as discussed below with respect to  FIGS. 9-11 . 
     As depicted in  FIGS. 2A-2C , an input/output module may be attached to a cover of an electronic device. The input/output module detects touch and/or force inputs on the cover, and outputs localized haptic feedback to the cover. While in the following examples the term “cover” may refer to a cover for a trackpad, it should be understood that the term “cover” may also refer to a portion of an enclosure (such as the enclosure  101  depicted in  FIG. 1 ). 
       FIG. 2A  depicts an example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating detection of a touch location. As depicted in  FIG. 2A , an input device  208  includes a cover  210  defining an input surface, and an input/output module  205  is attached or otherwise coupled to the cover  210 . The input/output module  205  may be attached to the cover  210  through an appropriate means, such as depicted in  FIGS. 5A-5F, 8B, and 8C . 
     As an object, such as a finger  212  approaches and/or comes in contact with the cover  210 , the input/output module  205  may detect the touch. In an example embodiment, the input/output module  205  may include an input electrode which detects the touch as a change in capacitance. The input electrode may operate through self-capacitance (as depicted in  FIGS. 3A-3C ) or through mutual capacitance (as depicted in  FIGS. 4A-4C ). The input electrode may be coupled to processing circuitry to determine the presence and location of the finger  212  on the input surface of the cover  210 . 
     In addition, as depicted in  FIG. 2B , the finger  212  or other object may exert force or pressure on the cover  210 . This force may deflect the cover  210 , which may in turn deflect the input/output module  205 . As the input/output module  205  is deflected, an input electrode may have a non-binary response to the deflection, which response corresponds to and indicates the amount of force applied to the cover  210 . 
     In an example embodiment, the input electrode may be a strain gauge which undergoes a change in resistance in response to deflection of the input/output module  205 . The input electrode may be coupled to processing circuitry to estimate or otherwise determine the amount of force applied to the cover  210  based on the resistive response. In other embodiments, an input electrode may be otherwise responsive to strain. For example, the input electrode may be formed from a piezoresistive, piezoelectric, or similar material having an electrical property that changes in response to stress, strain, and/or deflection. 
     As depicted in  FIG. 2C , the input/output module  205  may also provide localized haptic feedback to the cover  210 . The input/output module  205  may include a haptic actuator which is coupled to processing circuitry and/or a signal generator. The processing circuitry and/or signal generator may actuate the haptic actuator by applying an electrical signal to the haptic actuator. 
     When an electrical signal is applied to the haptic actuator, the haptic actuator may cause the input/output module  205  to deflect upward. For example, the haptic actuator may include a piezoelectric element with a pair of electrodes coupled to opposing sides of the piezoelectric element (e.g., a top and bottom, which may be parallel to the cover  210 ). When an electrical signal is applied to the piezoelectric element, the piezoelectric element may contract along a first direction parallel to the electrodes. With the piezoelectric element coupled to a substrate, the contraction may cause the piezoelectric element to bend along a second direction transverse to the first direction. This bending of the piezoelectric element may cause the input/output module  205  to which the piezoelectric element is coupled to deflect upward toward the cover  210 . 
     As the input/output module  205  deflects upward, it may cause one or more sections of the cover  210  to deflect or move to provide localized haptic feedback to the user. In particular, the cover  210  bends or deflects at a location that substantially corresponds to the location of the haptic actuator. This deflection of the cover  210  may be felt or otherwise perceived by a user through a finger  212  in contact with the cover  210 . 
     The haptic actuator may be actuated in response to a variety of stimuli, such as a touch input, a force input, the operation of software executed by the processing circuitry, and so on. For example, the input/output module  205  may cause haptic feedback at the cover  210  in response to an amount of force exerted on the cover  210  exceeding a threshold (e.g., similar to a button press). In another example, software executed by the processing circuitry may cause the input/output module  205  to provide haptic feedback in response to events which occur during execution of the software. 
     It should be understood that  FIGS. 2A-2C  present cross-sectional views which may omit certain components for clarity. For example, as depicted in  FIGS. 5A-5F, 8B, and 8C , the input/output module  205  may include multiple layers and components. One or more additional layers, such as an adhesive layer, may also be included between the cover  210  and the input/output module  205 . The input device and/or the electronic device may also include additional components and structures, such as the components depicted in  FIG. 11 , support structures, and the like. 
     Turning to  FIGS. 3A-3C , an input electrode of the input/output module may include a strain gauge which operates to detect touch through self-capacitance, and force may be detected through a resistive strain response of the input electrode.  FIG. 3A  is a top view of an input device, while  FIGS. 3B and 3C  are cross-sectional views of the input device. 
       FIG. 3A  depicts a top view of an input device illustrating an example touch and/or force-sensing input electrode. The input device  308  may be any input device configured to detect touch and/or force inputs, such as the trackpad depicted in  FIG. 1 . The input device  308  includes a cover  310  defining an input surface, and an input electrode  306  positioned below the cover  310 . A finger  312  or other object may approach or contact the input surface of the cover  310 . 
     As depicted in  FIG. 3A , in some embodiments the input electrode  306  may be a strain gauge formed from a conductive material patterned into a spiral pattern, which includes a set of parallel lines. In other embodiments, the input electrode  306  may be any type of sensor which responds to touch inputs and strain inputs, in which touch and strain may be distinguished. For example, the input electrode  306  may be formed from a piezoresistive, piezoelectric, or similar material having an electrical property (e.g., a resistance or resistivity) that changes in response to stress, strain, and/or deflection. 
     Turning to  FIG. 3B , in some embodiments the input electrode  306  may operate to detect touch through self-capacitance. Thus, the conductive material of the input electrode  306  may be energized (e.g., driven) with an alternating current or direct current signal (e.g., from a signal generator). When a user&#39;s finger  312  approaches or comes in contact with the cover  310 , a touch capacitance C may be formed between the finger  312  and the input electrode  306 . The touch capacitance C formed between the finger  412  and the input electrode  306  (or change in capacitance) may be detected by processing circuitry coupled to the input electrode  306 , which may indicate a touch input to the input surface of the cover  310 . 
     As depicted in  FIG. 3C , a force F applied to the cover  310  may be detected through the same input electrode  306 . The input electrode  306  may be energized (e.g., driven) with an alternating current or direct current signal (e.g., from a signal generator). As a finger  312  or other object exerts a force F on the cover  310 , the cover  310  may deflect and cause a strain on the input electrode  306 . For example, the geometry of the conductive traces of the input electrode  306  may change in response to the cover  310  deflection (e.g., the traces may be stretched and/or compressed). This change in geometry may result in a change in resistance through the input electrode  306 , which may be detected by processing circuitry coupled to the input electrode  306 . The processing circuitry may further estimate or otherwise determine a non-binary amount of force applied to the cover  310  based on the change in resistance. 
     A “non-binary” amount of force or force input signal is one that may be registered as more than two possible values. Put another way, non-binary force input signals may have intermediate values, outputs, or states other than zero and a maximum (or off and on). Such non-binary signals may have a series of values, which may be discrete or continuous, each corresponding to a variety of input forces beyond binary options. Stated in another way, the force signal may vary in magnitude in accordance with a force that is applied to the cover. 
     In some embodiments, the input electrode  306  may be energized with an electrical signal (e.g., driven with a drive signal), and touch inputs may be detected or measured as a capacitive response to the signal while force inputs may be detected or measured as a resistive response to the signal. In other embodiments, touch and/or force sensing may be time multiplexed. The input electrode  306  may be driven with a first signal (e.g., a signal having a first waveform, which may include A/C and/or D/C components, and may have a given amplitude, shape, and/or frequency) for a first period of time, and a touch input may be measured as a capacitive response to the first signal. The input electrode  306  may be driven with a second signal (e.g., a signal having a second waveform, which may include A/C and/or D/C components, and may have a given amplitude, shape, and/or frequency) for a second period of time, and a force input may be measured as a resistive response to the second signal. In still other embodiments, a same signal may be used to drive the input electrode  306 , but the touch response may be measured during a first period of time and the force response may be measured during a second period of time. 
     Turning to  FIGS. 4A-4C , two or more input electrodes of the input/output module may include strain gauges. The input electrodes may operate to detect touch through mutual capacitance between the input electrodes, and force may be detected through a resistive strain response of the input electrodes. 
       FIG. 4A  depicts a top view of an input device illustrating an example pair of touch and/or force-sensing input electrodes. The input device  408  may be any input device configured to detect touch and/or force inputs, such as the trackpad depicted in  FIG. 1 . The input device  408  includes a cover  410  defining an input surface, and input electrodes  406   a,    406   b  positioned below the cover  410 . A finger  412  or other object may approach or contact the input surface of the cover  410 . 
     Turning to  FIG. 4B , in some embodiments the input electrode may operate to detect touch through mutual capacitance. Thus, a first input electrode, designated a drive input electrode  406   a,  may be driven with an alternating current or direct current signal (e.g., from a signal generator). A cross-capacitance C 1  may be formed between the drive input electrode  406   a  and a second input electrode adjacent the drive input electrode  406   a,  designated a sense input electrode  406   b,  in response to the drive signal. When a user&#39;s finger  412  approaches or comes in contact with the cover  410 , a touch capacitance C 2  may be formed between the finger  412  and the drive input electrode  406   a  and/or the sense input electrode  406   b.  The touch capacitance C 2  may in turn alter the cross-capacitance C 1 . 
     Processing circuitry may be coupled to the drive input electrode  406   a  and/or sense input electrode  406   b  to detect the change in the cross-capacitance C 1 . In some embodiments, processing circuitry may monitor the sense input electrode  406   b  for a change in capacitance which may indicate a touch input to the input surface of the cover  410 . In other embodiments, processing circuitry may monitor a capacitance across the drive input electrode  406   a  and the sense input electrode  406   b,  or by a similar technique. 
     As depicted in  FIG. 4C , a force F applied to the cover  410  may be detected through one or both of the drive input electrode  406   a  and the sense input electrode  406   b.  For example, the drive input electrode  406   a  and the sense input electrode  406   b  may each be driven with an alternating current or direct current signal (e.g., from a signal generator). As a finger  412  or other object exerts a force F on the cover  410 , the cover  410  may deflect and cause a strain on the input electrodes  406   a,    406   b.  Processing circuitry may monitor the drive input electrode  406   a  and the sense input electrode  406   b  for a change in resistance, corresponding to a non-binary force applied to the cover  410 . In other embodiments, the only one of the drive input electrode  406   a  and the sense input electrode  406   b  may be driven and monitored for a change in resistance. 
     Turning to  FIGS. 5A-5F , example cross-sections of an input device according to the present disclosure are illustrated. Each example includes in input/output module which operates as described above with respect to  FIGS. 1-4C . 
       FIG. 5A  depicts an example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a first example input/output module. An input device  508  includes a cover  510  and an input/output module  505   a  coupled to the cover  510 . 
     Generally, the cover  510  is formed from a dielectric material, such as glass, plastic, acrylic, and other non-conductive materials. In some cases, the cover may be formed from an opaque material and/or include an opaque layer, such as an ink layer. In other cases, the cover  510  may be transparent or partially transparent. While in these examples the term “cover” may refer to a cover for a trackpad, it should be understood that the term “cover” may also refer to a portion of an enclosure (such as the enclosure  101  depicted in  FIG. 1 ). For example, the cover  510  may enclose a virtual keyboard having dynamically adjustable input regions defined by the input/output module  505   a , a sidewall of an electronic device, or the like. 
     The cover  510  may be coupled to the input/output module  505   a  by an adhesive layer  540 . The adhesive layer  540  may include a pressure-sensitive adhesive, or another adhesive which couples the cover  510  to the input/output module  505   a  such that a deflection in the cover  510  is transferred through the adhesive layer  540  to the input/output module  505   a,  and a deflection of the input/output module  505   a  is transferred to the cover  510 . 
     The input/output module  505   a  includes a substrate  516  on which input electrodes  506  and haptic actuators  521   a  are disposed. The substrate  516  may include materials such as, but not limited to: plastic, ceramic, glass, polyimide, polyethylene terephthalate, silicone, fiber composite, or any combination thereof. In some embodiments, the substrate  516  may provide structural rigidity for the input electrodes  506  and/or a stiffener to improve performance of the haptic actuators  521   a.    
     One or more input electrodes  506  may be deposited on a top surface (e.g., the surface facing the cover  510 ) of the substrate  516 . Each input electrode  506  may be formed from a conductive material which is also responsive to strain, formed with a set of conductive traces arranged in a doubled-back spiral shape, such as depicted below with respect to  FIGS. 6B, 7A , and  7 B. In other embodiments, the shape or geometry of an input electrode  506  may vary. For example, an input electrode  506  may be formed from a set of traces arranged in a forked or comb-shaped configuration, a linear serpentine shape, a radial serpentine shape, a spiral shape, and so on. 
     The conductive material of the input electrodes  506  may include materials such as, but not limited to: gold, copper, copper-nickel alloy, copper-nickel-iron alloy, copper-nickel-manganese-iron alloy, copper-nickel-manganese alloy, nickel-chrome alloy, chromium nitride, a composite nanowire structure, a composite carbon structure, graphene, nanotube, constantan, karma, silicon, polysilicon, gallium alloy, isoelastic alloy, and so on. The conductive material of the input electrodes  506  may be formed or deposited on a surface using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. 
     Localized haptic feedback may be provided by means of the one or more haptic actuators  521   a  coupled to a bottom surface of the substrate  516 , opposite the input electrodes  506 . A haptic actuator  521   a  may include a piezoelectric element  522   a,  a top electrode  518   a,  and a bottom electrode  524   a.  The top electrode  518   a  (e.g., a conductive pad) and a conductive pad  520   a  may be formed from a conductive material deposited on the bottom surface of the substrate  516 . The bottom electrode  524   a  may wrap around a portion of the piezoelectric element and couple to the conductive pad  520   a.    
     The top electrode  518   a  and the conductive pad  520   a  may be disposed on a common layer, which may additionally include signal lines to transmit actuation signals to each haptic actuator  521   a  (e.g., such as depicted below with respect to  FIG. 6C ). Accordingly, a potential may be applied across the piezoelectric element  522   a —a reference voltage may be provided to the bottom electrode  524   a  through the conductive pad  520   a;  and an actuation signal may be provided to the top electrode  518   a.  In some embodiments, the top electrode  518   a  may be coupled to a reference voltage and the bottom electrode  524   a  may be coupled to an actuation signal. 
     Each haptic actuator  521   a  can be selectively activated in the embodiment shown in  FIG. 5A . In particular, the bottom electrode  524   a  can provide a reference voltage to a haptic actuator  521   a,  while the top electrode  518   a  can apply an electrical signal across each individual piezoelectric element  522   a  independently of the other piezoelectric elements  522   a.    
     When a voltage is applied across the piezoelectric element  522   a,  the voltage may induce the piezoelectric element  522   a  to expand or contract in a direction or plane substantially parallel to the substrate  516 . For example, the properties of the piezoelectric element  522   a  may cause the piezoelectric element  522   a  to expand or contract along a plane substantially parallel to the substrate when electrodes applying the voltage are placed on a top surface and bottom surface of the piezoelectric element  522   a  parallel to the substrate. 
     Because the top surface of the piezoelectric element  522   a  is attached to the substrate  516 , as the piezoelectric element  522   a  contracts along the plane parallel to the substrate, the piezoelectric element  522   a  may bow and deflect in a direction orthogonal to the substrate  516 , that is upward toward the cover  510 , such as depicted above with respect to  FIG. 2C . The haptic feedback may be localized to a portion of the cover  510  above the haptic actuator  521   a.    
     The piezoelectric element  522   a  may be formed from an appropriate piezoelectric material, such as potassium-based ceramics (e.g., potassium-sodium niobate, potassium niobate), lead-based ceramics (e.g., PZT, lead titanate), quartz, bismuth ferrite, and other suitable piezoelectric materials. The top electrode  518   a,  the bottom electrode  524   a,  and the conductive pad  520   a  are typically formed from metal or a metal alloy such as silver, silver ink, copper, copper-nickel alloy, and so on. In other embodiments, other conductive materials can be used. 
     In some embodiments, the top electrode  518   a  and the conductive pad  520   a  are formed or deposited directly on the substrate  516  using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. The piezoelectric element  522   a  may be similarly formed directly on the top electrode  518   a  and the conductive pad  520   a , and the bottom electrode  524   a  may be formed directly on the piezoelectric element  522   a  and the conductive pad  520   a.    
     While the haptic actuator  521   a  has been described with respect to a piezoelectric actuator, different types of haptic actuators  521   a  can be used in other embodiments. For example, in one embodiment one or more electromagnetic actuators can be disposed below the substrate  516  and used to produce localized deflection of the cover  510 . Alternatively, one or more piston actuators may be disposed below the cover  510 , and so on. 
     The relative position of the various layers described above may change depending on the embodiment. Some layers, such as the adhesive layer  540 , may be omitted in other embodiments. Other layers, such as the cover  510  and the substrate  516 , may not be uniform layers of single materials, but may include additional layers, coatings, and/or be formed from composite materials. The input device  508  and/or electronic device may include additional layers and components, such as processing circuitry, a signal generator, a battery, etc., which have been omitted from  FIGS. 5A-5F  for clarity. 
       FIG. 5B  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a second example input/output module. As depicted in  FIG. 5B , in some embodiments similar to  FIG. 5A  a haptic actuator  521   b  in the input/output module  505   b  may be selectively actuated through signals transmitted on two layers. 
     For example, the top electrode  518   b  may be deposited on the bottom surface of the substrate  516 . Signal lines may also be deposited on the bottom surface of the substrate  516  to transmit actuation signals to each top electrode  518   b  of a haptic actuator  521   b.  A piezoelectric element  522   b  be formed directly on the top electrode  518   b,  and the bottom electrode  524   b  may be formed on the piezoelectric element  522   b.    
     The input device  508  may also include a circuit layer  526   b  which includes signal lines to provide a common reference voltage to each bottom electrode  524   b  of a haptic actuator  521   b.  The circuit layer  526   b  may be a flexible printed circuit or a flexible printed circuit board. The circuit layer  526   b  can be made from any number of suitable materials, such as polyimide or polyethylene terephthalate, with conductive traces for signal lines formed from materials such as copper, silver, aluminum, and so on. 
     The circuit layer  526   b  may be coupled to each haptic actuator  521   b  in a manner that electrically couples a signal line or common reference voltage plate on the circuit layer  526   b  to each bottom electrode  524   b.  For example, the circuit layer  526   b  may be coupled to each haptic actuator  521   b  by an adhesive layer, such as an isotropic or anisotropic conductive film, by soldering, and other appropriate techniques. 
     Accordingly, a potential may be applied across the piezoelectric element  522   b,  with a common reference voltage provided to each bottom electrode  524   b  and a signal line provided to each top electrode  518   b.  A top electrode  518   b  may receive an actuation signal, and the voltage across the piezoelectric element  522   b  may cause the haptic actuator  521   b  to deflect, which in turn provides localized haptic feedback at the cover  510 . 
     In some embodiments, the top electrodes  518   b  may form a common reference layer, and actuation signals may be transmitted to the bottom electrodes  524   b.  In such cases, the top electrodes  518   b  may be formed as an interconnected conductive layer (partially or entirely formed of conductive material), while the circuit layer  526   b  may include separate signal lines to provide actuation signals to each bottom electrode  524   b.    
       FIG. 5C  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a third example input/output module. As depicted in  FIG. 5C , in some embodiments similar to  FIG. 5A  a haptic actuator  521   c  in the input/output module  505   c  may be formed with a dielectric  530  separating the conductive pad  520   c  from the top electrode  518   c.    
     For example, a top electrode  518   c  and a conductive pad  520   c  may be disposed on a common layer, which may additionally include signal lines to transmit actuation signals to each haptic actuator  521   c  (e.g., such as depicted below with respect to  FIG. 6C ). A dielectric  530  may be deposited between the conductive pad  520   c  and the top electrode  518   c  to electrically isolate the conductive pad  520   c  from the top electrode  518   c.  The dielectric  530  further isolates the top electrode  518   c  and the bottom electrode  524   c.    
     The dielectric  530  may be formed from silicon dioxide, hafnium oxide, tantalum oxide, nanopourous silica, hydrogensilsesquioxanes, polytetrafluoethylene, silicon oxyflouride, or another suitable dielectric material. The dielectric  530  may be formed or deposited using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. 
     A connecting line  528   c  may be deposited over the dielectric  530 , electrically coupling the conductive pad  520   c  to the bottom electrode  524   c.  The connecting line  528   c  may be formed from a similar material and using a similar technique as described above with respect to the conductive pad  520   c  and the top electrode  518   c.  A potential may be applied across the piezoelectric element  522   c —a reference voltage may be provided to the bottom electrode  524   c  through the conductive pad  520   c  and the connecting line  528   c;  and an actuation signal may be provided to the top electrode  518   c.  In some embodiments, the top electrode  518   c  may be coupled to a reference voltage and the bottom electrode  524   c  may be coupled to an actuation signal. 
       FIG. 5D  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a fourth example input/output module. As depicted in  FIG. 5D , in some embodiments similar to  FIG. 5A  a haptic actuator  521   d  in the input/output module  505   d  may be formed by interleaving electrodes  525   d,    519   d  in the piezoelectric element  522   d.    
     By forming a haptic actuator  521   d  with interleaving electrodes  525   d,    519   d,  the piezoelectric element  522   d  may operate effectively as two stacked piezoelectric elements  522   d,  which may improve the performance of the haptic actuator  521   d  when actuated. The top electrode  518   d  may be formed on the substrate  516 , less than the entire width of the piezoelectric element  522   d,  and may be connected to signal lines disposed on the substrate  516 . 
     The material of the piezoelectric element  522   d  may be deposited over the top electrode  518   d,  and an intermediate bottom electrode  525   d  may be formed on the piezoelectric material, spanning less than the entire width of the piezoelectric element  522   d.  Additional material of the piezoelectric element  522   d  may be deposited on the intermediate bottom electrode  525   d,  and an intermediate top electrode  519   d  may be deposited on the piezoelectric material, spanning less than the entire width of the piezoelectric element  522   d.    
     Additional material of the piezoelectric element  522   d  may be deposited on the intermediate top electrode  519   d.  The bottom electrode  524   d  may be deposited over the piezoelectric element  522   d.  A bottom connecting line  528   d  may electrically connect the intermediate bottom electrode  525   d  and the bottom electrode  524   d  to signal lines disposed on the substrate  516 . A top connecting line  532   d  may electrically connect the intermediate top electrode  519   d  to the top electrode  518   d.    
     Accordingly, the haptic actuator  521   d  may be effectively two actuators, with the top electrode  518   d  and the intermediate bottom electrode  525   d  forming a first actuator. The intermediate top electrode  519   d  and the bottom electrode  524   d  form a second electrode. A potential may be applied across the portions of the piezoelectric element  522   d  between the electrodes. For example, a reference voltage may be provided to the intermediate bottom electrode  525   d  and the bottom electrode  524   d  through the bottom connecting line  528   d;  and an actuation signal may be provided to the top electrode  518   d  and the intermediate top electrode  519   d  through the top connecting line  532   d.  In some embodiments, the top electrode  518   d  and intermediate top electrode  519   d  may be coupled to a reference voltage and the intermediate bottom electrode  525   d  and the bottom electrode  524   d  may be coupled to an actuation signal. 
       FIG. 5E  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a fifth example input/output module. As depicted in  FIG. 5E , in some embodiments similar to  FIG. 5A  a haptic actuator  521   e  may be separately formed and coupled to the input/output module  505   e.    
     For example, the haptic actuator  521   e  may be formed by a separate process rather than being deposited onto the substrate  516 . A voltage may be applied across the piezoelectric element  522   e  via electrodes  518   e,    524   e  formed on opposing surfaces of the piezoelectric element  522   e.  A top electrode  518   e  is formed on a top surface of the piezoelectric element  522   e,  while a bottom electrode  524   e  is formed on a bottom surface of the piezoelectric element  522   e.  In many embodiments, the bottom electrode  524   e  wraps around the piezoelectric element  522   e  such that a portion of the second electrode is disposed on the top surface of the piezoelectric element  522   e.  In this manner, a reference voltage and actuation signal may be provided at a same interface. 
     The electrodes  518   e,    524   e  may be formed from a suitable conductive material, such as metal (e.g., silver, nickel, copper, aluminum, gold), polyethyleneioxythiophene, indium tin oxide, graphene, piezoresistive semiconductor materials, piezoresistive metal materials, and the like. The top electrode  518   e  may be formed from the same material as the bottom electrode  524   e,  while in other embodiments the electrodes  518   e,    524   e  may be formed from different materials. The electrodes  518   e,    524   e  may be formed or deposited using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, plating, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. A mask or similar technique may be applied to form a patterned top surface of the piezoelectric element  522   e  and/or a wraparound bottom electrode  524   e.    
     A first conductive pad  520   e  and a second conductive pad  534   e  may be formed from a conductive material deposited on the bottom surface of the substrate  516 . The first conductive pad  520   e  and the second conductive pad  534   e  may be disposed on a common layer, which may additionally include signal lines to transmit actuation signals to each haptic actuator  521   e  (e.g., such as depicted below with respect to  FIG. 6C ). 
     The piezoelectric element  522   e  may be coupled to the first conductive pad  520   e  and the second conductive pad  534   e  by an adhesive layer  536   e,  which may be an anisotropic conductive film. The anisotropic conductive film of the adhesive layer  536   e  may facilitate conduction from the first conductive pad  520   e  to the bottom electrode  524   e  and from the second conductive pad  534   e  to the top electrode  518   e.  The anisotropic conductive film may further isolate these conduction paths to prevent an undesired short between the conductive pads  520   e,    534   e  or electrodes  518   e,    524   e.    
     In other embodiments, the piezoelectric element  522   e  may be coupled and electrically connected to the first conductive pad  520   e  and the second conductive pad  534   e  by isolated segments of isotropic conductive film, an anisotropic or isotropic conductive paste, or another appropriate method. 
       FIG. 5F  depicts another example cross-sectional view of the electronic device depicted in  FIG. 1 , taken along section A-A, illustrating a sixth example input/output module. As depicted in  FIG. 5F , in some embodiments similar to  FIG. 5A  a haptic actuator  521   f  may be separately formed and coupled to the input/output module  505   f  and a circuit layer  526   f.    
     For example, the haptic actuator  521   f  may be formed by a separate process rather than being deposited onto the substrate  516 . A top electrode  518   f  is formed on a top surface of the piezoelectric element  522   f,  while a bottom electrode  524   f  is formed on a bottom surface of the piezoelectric element  522   f  in a manner similar to that described above with respect to  FIG. 5E . 
     The input device  508  may also include a circuit layer  526   f  which includes signals lines to provide a common reference voltage to each bottom electrode  524   f  of a haptic actuator  521   f.  The circuit layer  526   f  may be a flexible printed circuit or a flexible printed circuit board, similar to that described above with respect to  FIG. 5B . The circuit layer  526   f  may include a first conductive pad  520   f  for each haptic actuator  521   f.    
     A second conductive pad  534   f  may be formed from a conductive material deposited on the bottom surface of the substrate  516 . The second conductive pad  534   f  may be disposed on a layer which additionally includes signal lines to transmit actuation signals to each haptic actuator  521   f.    
     The piezoelectric element  522   f  may be coupled to the second conductive pad  534   f  by a first adhesive layer  536   f  and the first conductive pad  520   f  by a second adhesive layer  538 . The first adhesive layer  536   f  may be an anisotropic conductive film, which may facilitate conduction from the second conductive pad  534   f  to the top electrode  518   f.  The anisotropic conductive film may further isolate the conductive pad  534   f  and top electrode  518   f  of separate haptic actuators  521   f  to prevent an undesired short between haptic actuators  521   f.    
     In other embodiments, the top electrode  518   f  may be coupled and electrically connected to the second conductive pad  534   f  by isolated segments of isotropic conductive film, an anisotropic or isotropic conductive paste, or another appropriate method. 
     The circuit layer  526   f  may couple a reference voltage to each bottom electrode  524   f.  Accordingly, the second adhesive layer  538  may be an isotropic conductive film, anisotropic conductive film, a conductive paste, or other conductive adhesion material. 
     Accordingly, a potential may be applied across the piezoelectric element  522   f,  with a common reference voltage provided to each bottom electrode  524   f  and a signal line provided to each top electrode  518   f.  A top electrode  518   f  may receive an actuation signal, and the voltage across the piezoelectric element  522   f  may cause the haptic actuator  521   f  to deflect, which in turn provides localized haptic feedback at the cover  510 . 
     In some embodiments, the top electrodes  518   f  may form a common reference layer, and actuation signals may be transmitted to the bottom electrodes  524   f.  In such cases, the top electrodes  518   f  may be formed as an interconnected conductive layer (partially or entirely formed of conductive material), while the circuit layer  526   f  may include separate signal lines to provide actuation signals to each bottom electrode  524   f.  The second adhesive layer  538  may be an anisotropic conductive film or other adhesion material that isolates the first conductive pads  520   f  from each other. 
       FIG. 6A  depicts an example cross-sectional view of an input/output module illustrating the deposition of input electrodes on a top surface of a substrate and haptic actuators on a bottom surface of the substrate. The input/output module  605  may be similar to those depicted above with respect to  FIGS. 5A-5F . 
     The input/output module  605  includes a substrate  616  on which input electrodes  606  and haptic actuators  621  are disposed. Generally, a set or array of input electrodes  606  are disposed on a top surface of the substrate  616 , near a cover of an input device. A set or array of haptic actuators  621  is disposed on a bottom surface of the substrate  616 . Each haptic actuator  621  may include a piezoelectric element  622  between a conductive pad  620  and a top electrode  618  above, and a bottom electrode  624  below. 
       FIG. 6B  depicts an example top view of input electrodes deposited on the top surface of the substrate. As depicted, each input electrode  606  may be a touch- and strain-sensitive element, which may be a conductive trace deposited or otherwise formed on the substrate  616  as a strain gauge. Each input electrode  606  may be formed in a double-backed spiral shape. In other embodiments, the shape or geometry of an input electrode  606  may vary. For example, an input electrode  606  may be formed from a set of traces arranged in a forked or comb-shaped configuration, a linear serpentine shape, a radial serpentine shape, a spiral shape, and so on. In these and other embodiments, the input electrode  606  may include conductive traces set in one or more sets of parallel lines. 
     Each input electrode  606  includes or is electrically coupled to a first signal line  607  and a second signal line  609 , which lead across the substrate  616  to connect to processing circuitry and/or a signal generator, such as described below with respect to  FIG. 11 . A signal generator may provide electrical signals to each input electrode  606  through the first signal line  607  or the second signal line  609 . Processing circuitry may be coupled to one or both signal lines  607 ,  609  to detect a capacitive touch response and a resistive force response. That is, a presence and location of a touch may be detected through a change in capacitance of an input electrode  606 , or across multiple input electrodes  606  (see  FIGS. 3B and 4B , described above). A non-binary amount of force may be detected through a change in resistance through an input electrode  606  (see  FIGS. 3C and 4C , described above). 
     The signal lines  607 ,  609  may be formed of a similar material and in a similar process as the input electrodes  606 . In some embodiments, the input electrodes  606  and the signal lines  607 ,  609  are formed in a same processing step. In other embodiments, the input electrodes  606  are formed in one processing step and one or both signal lines  607 ,  609  are formed in a separate processing step. The input electrodes  606  and the signal lines  607 ,  609  may be arranged in any suitable pattern, such as a grid pattern, a circular pattern, or any other geometric pattern (including a non-regular pattern). 
       FIG. 6C  depicts an example bottom view of a conducting layer for haptic actuators, deposited on the bottom surface of the substrate.  FIG. 6C  is depicted with other elements of each haptic actuator  621  shown as ghosted lines in order to clarify an example layout of a conducting layer. 
     As depicted, a conductive pad  620  and a top electrode  618  (e.g., another conductive pad) may be provided for each haptic actuator  621 . Signal lines  619 ,  623  connect to each top electrode  618  and conductive pad  620  in order to electrically couple the haptic actuator  621  to a signal generator and/or processing circuitry and provide actuation signals. As shown, each conductive pad  620  may connect to a first signal line  619 , which may provide a reference voltage to a bottom electrode of the haptic actuator  621 . Each top electrode  618  may connect to a second signal line  623 , which may provide an actuation signal to the haptic actuator  621 . In other embodiments, the top electrodes  618  may be coupled to a reference voltage and the conductive pads  620  may receive an actuation signal. 
     The signal lines  619 ,  623  may be formed of a similar material and in a similar process as the conductive pads  620  and top electrodes  618 , described above with respect to  FIG. 5A . In some embodiments, the conductive pads  620 , top electrodes  618 , and signal lines  619 ,  623  are formed in a same processing step. In other embodiments, the conductive pads  620  and/or top electrodes  618  are formed in one processing step and one or more signal lines  619 ,  623  are formed in a separate processing step. The input electrodes  606  and the signal lines  607 ,  609  may be arranged in any suitable pattern, such as a grid pattern, a circular pattern, or any other geometric pattern (including a non-regular pattern). 
     In some embodiments, the input electrodes  606  and signal lines  607 ,  609  are formed on the top surface of the substrate  616  in one processing step, and the conductive pads  620 , top electrodes  618 , and signal lines  619 ,  623  are formed on the bottom surface of the substrate  616  in another processing step. In other embodiments, conducting material is formed on both sides of the substrate  616  in a same processing step. 
       FIGS. 7A and 7B  depict example input electrodes which may compensate for adverse environmental effects, such as changes in temperature. The performance of an input electrode  706   a,    706   b,    706   c  is dependent, in part, on the precision, accuracy, and resolution with which the strain experienced by the input electrode  706   a,    706   b,    706   c  may be estimated. As discussed above, processing circuitry may be configured to measure a change in the resistance of an input electrode  706   a,    706   b,    706   c  due to applied force. 
     However, an actual measurement of the resistance of an input electrode  706   a,    706   b,    706   c  may also be sensitive to variations in temperature, both across the device and localized over a portion of the device. Some embodiments of the input electrode  706   a,    706   b,    706   c  may be used to reduce or eliminate effects due to temperature or other environmental conditions. 
     For example,  FIG. 7A  depicts an example perspective view of a pair of input electrodes disposed adjacent one another over a substrate. In this configuration, a first input electrode  706   a  and a second input electrode  706   b  may be arranged in sufficient proximity that the two input electrodes  706   a,    706   b  experience approximately the same environmental effects. The output of the first input electrode  706   a  and the second input electrode  706   b  may be compared by processing circuitry to mitigate or eliminate variations in force measurements as a result of changing environmental conditions, such as changes in temperature. 
     As an example, the first input electrode  706   a  may be more responsive to strain along a particular direction than the second input electrode  706   b.  The resistive response to of the first input electrode  706   a  may then be compared to the resistive response of the second input electrode  706   b  (e.g., by subtracting the response of the second input electrode  706   b  from the first input electrode  706   a ) to account for temperature variation. 
       FIG. 7B  depicts another example perspective view of a pair of strain-sensitive element disposed above and below one another to form an input electrode. An input electrode  706   a  may include a first strain-sensitive element  770  disposed on the substrate  716 . A second strain-sensitive element  766  is disposed above the first strain-sensitive element  770 , with a film  768  or other dielectric material disposed between. In this configuration, the output of the first strain-sensitive element  770  may similarly be compared to the second strain-sensitive element  766  by processing circuitry to mitigate or eliminate variations in force measurements as a result of changes in temperature or other conditions. 
     As an example, the first strain-sensitive element  770  may be placed under compression while the second strain-sensitive element  766  may be placed under tension in response to a force on the cover. The distinct resistive responses of the first strain-sensitive element  770  and the second strain-sensitive element  766  may be compared to account for temperature variation. 
       FIG. 8A  depicts another electronic device with an input region having an integrated input/output module according to the present disclosure. In the illustrated embodiment, the electronic device  800  is implemented as a tablet computing device. 
     The electronic device  800  includes an enclosure  801  at least partially surrounding a display  802  and one or more input devices  842 . The enclosure  801  can form an outer surface or partial outer surface for the internal components of the electronic device  800 . The enclosure  801  can be formed of one or more components operably connected together, such as a front piece and a back piece. Alternatively, the enclosure  801  can be formed of a single piece operably connected to the display  802 . 
     The display  802  can provide a visual output to the user. The display  802  can be implemented with any suitable technology, including, but not limited to, a liquid crystal display element, a light emitting diode element, an organic light-emitting display element, an organic electroluminescence element, an electrophoretic ink display, and the like. 
     In some embodiments, the input device  842  can take the form of a home button, which may be a mechanical button, a soft button (e.g., a button that does not physically move but still accepts inputs), an icon or image on a display, and so on. Further, in some embodiments, the input device  842  can be integrated as part of a cover  810  and/or the enclosure  801  of the electronic device  800 . Although not shown in  FIG. 1 , the electronic device  800  can include other types of input and/or output devices, such as a microphone, a speaker, a camera, a biometric electrode, and one or more ports, such as a network communication port and/or a power cord port. 
     A cover  810  may be positioned over the front surface (or a portion of the front surface) of the electronic device  800 . While the cover  810  is depicted in reference to a cover over a display of a tablet computer, an input/output module may be positioned below other transparent or partially transparent covers, such as an enclosure of a device forming a virtual keyboard. The input/output module and the display  802  may define user input regions, such as dynamically configurable keys, which may receive force and touch inputs and provide haptic outputs to the cover  810 . 
     At least a portion of the cover  810  can function as an input surface that receives touch and/or force inputs. The cover  810  can be formed with any suitable material, such as glass, plastic, sapphire, or combinations thereof. In one embodiment, the cover  810  encloses the display  802  and the input device  842 . Touch and/or force inputs can be received by the portion of the cover  810  that encloses the display  802  and by the portion of the cover  810  that encloses the input device  842 . 
     In another embodiment, the cover  810  encloses the display  802  but not the input device  842 . Touch and/or force inputs can be received by the portion of the cover  810  that encloses the display  802 . In some embodiments, touch and/or force inputs can be received on other portions of the cover  810 , or on the entire cover  810 . The input device  842  may be disposed in an opening or aperture formed in the cover  810 . In some embodiments, the aperture extends through the enclosure  801  and one or more components of the input device  842  are positioned in the enclosure. 
     An input/output module may be incorporated below all or a portion of the cover  810 . The input/output module may detect touch inputs and force inputs on all or a portion of the cover  810 , and additionally may provide haptic feedback to the cover  810 . Examples of the electronic device  800  and the features of the input/output module are further depicted below with respect to  FIGS. 8B, 8C, 9, and 10 . Example components of the electronic device  800  are described below with respect to  FIG. 11 . 
       FIG. 8B  depicts an example cross-sectional view of the electronic device depicted in  FIG. 8A , taken along section B-B, illustrating a first example input/output module. An input device  808  includes a cover  810  defining an input surface, a display  802  below the cover  810 , and an input/output module  805  between the cover  810  and the display  802 . 
     The cover  810  is typically formed from a transparent dielectric material, such as glass, sapphire, plastic, acrylic, and other transparent, non-conductive materials. The cover  810  may be coupled to the input/output module  805  by an adhesive layer  840 . The adhesive layer  840  may include an optically clear adhesive, or another transparent adhesive which couples the cover  810  to the input/output module  805  such that a deflection in the cover  810  is transferred through the adhesive layer  840  to the input/output module  805 , and a deflection of the input/output module  805  is transferred to the cover  810 . 
     The input/output module  805  includes a substrate  816  on which input electrodes  806  and haptic actuators are disposed, in a manner similar to the input/output modules  505   a - 505   f  described above with respect to  FIGS. 5A-5F . The materials of the substrate  816 , the input electrodes  806 , and the piezoelectric elements  822  may be optically transparent. The piezoelectric elements  822  of the haptic actuators may be coupled to the substrate  816  through a conductive layer  818 , which may provide actuation signals to the piezoelectric elements  822 . 
     Conductive materials of the input/output module  805 , such as the input electrodes  806  and the conductive layer  818  may be formed from optically transparent materials, such as, but not limited to: indium-tin oxide, carbon nanotubes, metal nanowires, or any combination thereof. The piezoelectric element  822  may be formed from a transparent piezoelectric material, such as lithium niobate, quartz, and other suitable piezoelectric materials. 
     The display  802  may include a display element, and may include additional layers such as one or more polarizers, one or more conductive layers, and one or more adhesive layers. In some embodiments, a backlight assembly (not shown) is positioned below the display  802 . The display  802 , along with the backlight assembly, is used to output images on the display. In other embodiments, the backlight assembly may be omitted. 
       FIG. 8C  depicts another example cross-sectional view of the electronic device depicted in  FIG. 8A , taken along section B-B, illustrating a second example input/output module. In some embodiments, the display  802  may be positioned adjacent the cover  810 , and the input/output module  805  may be placed below the display  802 . 
     The input/output module  805  may be coupled to the display  802  by an adhesive layer  846 . The input/output module  805  may include a substrate  816  on which input electrodes  806 , and haptic actuators are disposed. The haptic actuators may include a conductive layer  818  and a piezoelectric element  822 . Each of these components may be similar to those described above with respect to  FIGS. 5A-5F and 8C , and may be optically transparent or opaque. 
     In various embodiments, the input/output modules shown and described with respect to  FIGS. 5A-8C  include haptic actuators and input electrodes disposed beneath a cover as part of a separate layer from the cover, such as a substrate. These are example arrangements of the haptic actuators with respect to the cover, and other arrangements are possible. For example, in some embodiments, one or more haptic actuators or input electrodes may be integrally formed with (e.g., on or within) a wall of an enclosure of a portable electronic device.  FIGS. 9-10D  depict example embodiments in which haptic actuators and input electrodes are integrally formed with (e.g., on or within) a wall of an enclosure. 
       FIG. 9  depicts an enclosure  900  for an electronic device  990  (e.g., a portable electronic device) having one or more components of an input/output module integrally formed with a wall of the enclosure. In some embodiments, the electronic device  990  is an electronic watch or smartwatch. In various embodiments, the enclosure  900  may include an enclosure component  901  and a cover  902 . The enclosure component  901  and the cover  902  may be attached or otherwise coupled and may cooperate to form the enclosure  900  and define one or more exterior surfaces of the electronic device  990 . In various embodiments, one or more input/output modules may be at least partially integrally formed with a wall  931  of the enclosure  900 . As used herein, “integrally formed with” may be used to refer to defining or forming a unitary structure. For example, one or more haptic actuators, input electrodes, and/or other components of an input/output module may be integrally formed on or within the wall  931  to form a unitary structure by co-firing or co-sintering the one or more haptic actuators, input electrodes, and/or other components with at least a portion of the enclosure  900 . 
     The wall  931  (e.g., a sidewall of the electronic device  990 ) defines at least a portion of an exterior surface of the enclosure  900  that is configured to receive a contact from a user. Integrally forming a haptic actuator within a wall of the enclosure allows for localized haptic feedback (e.g., localized deflection of the wall  931 ) to be produced at select locations along an exterior surface of the enclosure, for example in response to a touch input detected along the exterior surface. Similarly, integrally forming an input electrode within a wall of the enclosure allows for localized touch input and force input detection at select locations along the exterior surface of the enclosure. 
     In various embodiments, the enclosure  900 , including the enclosure component  901 , may be formed from a variety of materials including polymers (e.g., polycarbonate, acrylic), glass, ceramics, composites, metal or metal alloys, (e.g., stainless steel, aluminum), precious metals (e.g., gold, silver), or other suitable materials, or a combination of these materials. In some embodiments, the enclosure component  901  is at least partially formed from a ceramic material such as aluminum oxide (alumina) or other similar type of material. In various embodiments, the enclosure component  901  may be co-fired with one or more components of the input/output module and/or other components of the electronic device  990 . As used herein, “co-firing” may be used to refer to any process by which one or more components or materials are fired in a kiln or otherwise heated to fuse or sinter the materials at the same time. For the purposes of the following discussion, “co-firing” may be used to refer to a process in which two materials, which are in a green, partially sintered, pre-sintered state are heated or sintered together for some period of time. In various embodiments, a co-firing process may include low temperature (LTCC) applications (e.g., sintering temperatures below 1000 degrees Celsius) and/or high temperature (HTCC) applications (e.g., high temperatures between 1000 and 1800 degrees Celsius). In various embodiments, co-firing components of the electronic device  990  may improve the electronic device by reducing device dimensions (e.g., thickness of a wall or other component), reducing or eliminating the need for adhesives to join components together, simplifying manufacturing, and the like. 
     In some embodiments, one or more components of the input/output module are at least partially formed of a ceramic material. For example, the input/output module may include one or more piezoelectric ceramic actuators, ceramic buffers, or the like, as discussed below. More specifically, as described in more detail below, the input/output module may include a piezoelectric element that is configured to produce a localized deflection along the exterior surface of the enclosure component  901 . If the enclosure component  901  and the piezoelectric element are both formed from ceramic materials, the two components may be integrally formed using a co-firing or co-sintering process. 
     In some embodiments, the cover  902  may include a sheet or cover sheet that is positioned over a display of the electronic device  990 . The display may include one or more input devices or touch sensors and be configured as a touch-sensitive or touchscreen display. The touch sensors may include input electrodes or electrodes in accordance with embodiments described herein. Specifically, the touch sensors may include an array of input electrodes that are configured to detect a location of a touch input along the cover  902 . In some instances, an array of electrodes that are configured to detect a force of a touch input are positioned along or below the cover  902 . 
     The cover  902  may be formed from an optically transmissive material to allow images or light to be visible therethrough. As used herein, “optically transmissive” or “light-transmissive” may be used to refer to something that is transparent or translucent, or otherwise allows light or other electromagnetic radiation to propagate therethrough. In some cases, transparent materials or components may introduce some diffusion, lensing effects, distortions, or the like (e.g., due to surface textures) while still allowing objects or images to be seen through the materials or components, and such deviations are understood to be within the scope of the meaning of transparent. Also, materials that are transparent may be coated, painted, or otherwise treated to produce a non-transparent (e.g., opaque) component; in such cases the material may still be referred to as transparent, even though the material may be part of an opaque component. Translucent components may be formed by producing a textured or frosted surface on an otherwise transparent material (e.g., clear glass). Translucent materials may also be used, such as translucent polymers, translucent ceramics, or the like. 
     Various components of an electronic device  990  may be coupled to and/or positioned within the enclosure  900 . For example, processing circuitry of the electronic device may be housed or positioned within an internal volume  921  of the enclosure  900 . Additional components of the electronic device are discussed in more detail below with respect to  FIG. 15 . Although the enclosure  900  is pictured as having a rectangular shape, this is one example and is not meant to be limiting. In various embodiments, the electronic device may be and/or take the form of a personal computer, a notebook or laptop computer, a tablet, a smart phone, a watch, a case for an electronic device, a home automation device, and so on. 
     In some embodiments, the enclosure component  901  defines a wall  931  (e.g., sidewall or enclosure wall) that defines at least a portion of an exterior surface  911  of the enclosure  900 .  FIG. 10A  depicts an example partial cross-sectional view of the electronic device  990  depicted in  FIG. 9 , taken along section C-C. The electronic device  990  includes an input/output module  1050   a.  The input/output module  1050   a  includes one or more haptic actuators  1051 , and one or more input electrodes  1060 ,  1070 . In various embodiments, the input/output module  1050   a  may be at least partially integrated or integrally formed with the wall  931 . For example, as shown in  FIG. 10A , one or more haptic actuators  1051  may be formed within the structure of the wall  931 . As previously mentioned, if the haptic actuator  1051  is formed form a ceramic (e.g., ceramic piezoelectric) material, the haptic actuator  1051  may be integrally formed with a structure of the enclosure by being co-fired or co-sintered with the wall  931  of the enclosure  900 . 
     As shown in  FIG. 10A , one or more input electrodes  1060   a,    1060   b  may be deposited on or within the wall  931 . For example, as shown in  FIG. 10A , the input electrodes  1060   a,    1060   b  may be deposited on an interior surface  1004  of the wall  931 . Each input electrode  1060   a,    1060   b  may be formed from a conductive material arranged in a pattern suitable to detect touch inputs, for example along a portion of the exterior surface located along the wall  931 . For example, the input electrodes  1060   a,    1060   b  may be arranged in square or rectangular shapes, such as described with respect to  FIG. 10B . The input electrodes  1060   a,    1060   b  alone or in combination with other electrodes may define an array of input electrodes. In some instances, at least a portion of the array of electrodes defines a touch sensor or a portion of the touch screen that is positioned below the cover (e.g., cover  902  of  FIG. 9 ). 
       FIG. 10B  depicts an example view of input electrodes deposited on the interior surface  1004  of the wall  931 , taken through section D-D of  FIG. 10A . As depicted, each input electrode  1060   a,    1060   b  may be a touch- and/or strain-sensitive element, which may be a conductive trace deposited or otherwise formed on or within the wall  931 . In some embodiments, one or more input electrodes are responsive to strain and may be configured to produce an electrical signal or have an electrical characteristic (e.g., resistance) that is responsive to a force applied to the wall  931 . In some embodiments, one or more input electrodes are may be configured to produce an electrical signal or have an electrical characteristic (e.g., capacitance) that is responsive to a touch input applied along the wall  931 . 
     The arrangement and function of the input electrodes  1060   a,    106   b  may vary depending on the implementation. In some embodiments, input electrode  1060   a  is a touch-sensing input electrode and input electrode  1060   b  is a force-sensing input electrode. In some embodiments, the input electrodes  1060   a,    1060   b  are touch-sensing and force-sensing electrodes. In various embodiments, the shape or geometry of an input electrode  1060  may vary. For example, an input electrode may be formed from a set of conductive traces arranged in a doubled-back spiral shape, a forked or comb-shaped configuration, a linear serpentine shape, a radial serpentine shape, a spiral shape, and so on. In these and other embodiments, the input electrode  1060   a,    1060   b  may include conductive traces set in one or more sets of parallel lines. 
     Each input electrode  1060   a,    1060   b  includes or is electrically coupled to one or more signal lines (e.g., one or more signal lines of a signal trace  1080 ). A signal generator may provide electrical signals to each input electrode  1060   a,    1060   b  through the signal line(s). Processing circuitry may be coupled to the signal line(s) to detect a capacitive touch response and a resistive force response. For example, a presence and/or location of a touch input may be detected through a change in capacitance of an input electrode  1060   a,    1060   b,  or across multiple input electrodes  1060   a,    1060   b  (see  FIGS. 3B and 4B , described above). Further, an amount of force may be detected using a change in resistance through an input electrode  1060   a,    1060   b  to produce a non-binary force signal or output (see  FIGS. 3C and 4C , described above). 
     The conductive material of the input electrodes  1060   a,    1060   b  may include materials such as, but not limited to: gold, copper, copper-nickel alloy, copper-nickel-iron alloy, copper-nickel-manganese-iron alloy, copper-nickel-manganese alloy, nickel-chrome alloy, chromium nitride, a composite nanowire structure, a composite carbon structure, graphene, nanotube, constantan, karma, silicon, polysilicon, gallium alloy, isoelastic alloy, and so on. The conductive material of the input electrodes  1060   a,b  may be formed or deposited on a surface using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. In some embodiments, the input electrodes may be co-fired with one or more components of the input/output module and/or the enclosure component  901 , such as described below with respect to  FIGS. 10C and 10D . 
     As described above, in some embodiments one or more signal lines may be included in a signal trace  1080 . The signal lines may be formed of a similar material and in a similar process as the input electrodes  1060   a,    1060   b.  In some embodiments, the input electrodes  1060   a,    1060   b  and the signal lines are formed in a same processing step. In other embodiments, the input electrodes  1060   a,    1060   b  are formed in one processing step and one or both signal lines are formed in a separate processing step. The input electrodes  1060   a,    1060   b  and the signal lines may be arranged in any suitable pattern, such as a grid pattern, a circular pattern, or any other geometric pattern (including a non-regular pattern). 
     As discussed above, in various embodiments, localized haptic feedback may be provided by means of the one or more haptic actuators  1051  that are integrally formed with the wall  931 . A haptic actuator  1051  may include a piezoelectric element  1052 , a first electrode  1053 , and a second electrode  1054 . The second electrode  1054  (e.g., a conductive pad) may be formed from a conductive material deposited on the internal surface  1004  of the enclosure component  901 . In some embodiments, the second electrode  1054  is integrally formed with the wall  931  and may define a conductive portion of the internal surface  1004 . The first electrode  1053  may extend beyond and/or wrap around a portion of the piezoelectric element and couple to a conductive pad  1055  and/or a trace  1080 . The conductive pad  1055  may be formed from a conductive material deposited on the internal surface  1004  and/or integrally formed with the wall  931 . In some embodiments, the second electrode  1054  is integrally formed with the wall  931  and may define a conductive portion of the interior surface  1004 . 
     One or more signal lines (e.g., signal trace  1080 ) may be conductively coupled with the conductive pad  1055 , the first electrode  1053  and/or the second electrode  1054  to transmit actuation signals to each haptic actuator  1051 . Accordingly, a potential may be applied across the piezoelectric element  1052 —a reference voltage may be provided to the second electrode  1054 ; and an actuation signal may be provided to the first electrode  1053 . In some embodiments, the first electrode  1053  may be coupled to a reference voltage and the second electrode  1054  may be coupled to an actuation signal. In various embodiments the reference voltage may be ground. The signal trace  1080  may couple the input electrodes  1060   a,    1060   b,  the haptic actuators  1051 , and/or other components of the electronic device  990  to one or more additional components of the electronic device  990 . In some embodiments, the signal trace  1080  is coupled to processing circuitry disposed in the interior volume of the electronic device  990 . 
     Each haptic actuator  1051  can be selectively activated in the embodiment shown in  FIG. 10A . In particular, the second electrode  1054  can provide a reference voltage to a haptic actuator  1051 , while each first electrode  1053  can apply an electrical signal across each individual piezoelectric element  1052  independently of the other piezoelectric elements  1052 . In response to a drive voltage or signal, the haptic actuator  1051  (including piezoelectric element  1052 ) may produce a localized deflection or haptic output along the wall  931 . The localized deflection or haptic output may be tactically perceptible through a touch of the user&#39;s finger or other part of the user&#39;s body. The localized deflection or haptic output may be provided in response to detecting a touch input along the exterior surface of the electronic device. 
     As described above, when a voltage is applied across the piezoelectric element  1052  (or other type of haptic actuator), the voltage may induce the piezoelectric element  1052  to expand or contract in a direction or plane substantially parallel to the interior surface  1004  and/or the exterior surface  911 . For example, the properties of the piezoelectric element  1052  may cause the piezoelectric element  1052  to expand or contract along a plane substantially parallel to the interior surface  1004  and/or the exterior surface  911  when electrodes applying the voltage are placed on a top surface and bottom surface of the piezoelectric element  1052  parallel to the interior surface  1004  and/or the exterior surface  911 . 
     Because the piezoelectric element  1052  is fixed with respect to the wall  931 , as the piezoelectric element  1052  contracts along the plane parallel to the interior surface  1004  and/or the exterior surface  911 , the piezoelectric element  1052  may bow and deflect in a direction orthogonal to the interior surface  1004  and/or the exterior surface  911  (e.g., rightward toward the exterior surface  911  with respect to  FIG. 10A ), thereby causing the wall  931  to bow and/or deflect to provide a haptic output. The haptic output may be localized to a portion of the exterior surface  911  close to the haptic actuator  1051  (e.g., a portion of the exterior surface  911  rightward of the haptic actuator  1051  with respect to  FIG. 10A ). 
     While the haptic actuator  1051  may be a piezoelectric actuator, different types of haptic actuators  1051  can be used in other embodiments. For example, in some embodiments, one or more piston actuators may be disposed within the wall  931 , and so on. In various embodiments, when an actuation signal is applied to the haptic actuator  1051 , the haptic actuator may actuate to cause the wall  931  to bow and/or deflect to produce a haptic output. For example, a piston of the actuator may move in a direction that is substantially perpendicular to the exterior surface  911  to create a deflection in the wall  931 . The haptic output may be localized to a portion of the exterior surface  911  close to the haptic actuator  1051 . In some embodiments, a piezoelectric actuator may change thickness in a direction that is substantially perpendicular to the exterior surface  911 , which may in turn cause the wall  931  to bow and/or deflect to produce a haptic output. 
     The piezoelectric element  1052  may be formed from an appropriate piezoelectric material, such as potassium-based ceramics (e.g., potassium-sodium niobate. potassium niobate), lead-based ceramics (e.g., PZT, lead titanate), quartz, bismuth ferrite, and other suitable piezoelectric materials. The first electrode  1053 , the second electrode  1054 , and the conductive pad  1055  are typically formed from metal or a metal alloy such as silver, silver ink, copper, copper-nickel alloy, and so on. In other embodiments, other conductive materials can be used. 
     In some embodiments, the second electrode  1054  and the conductive pad  1055  are formed or deposited directly on the interior surface  1004  using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. 
     In some embodiments, one or more components of the haptic actuator  1051 , the conductive pad  1055 , the trace  1080 , and/or one or more input electrodes  1060  may be co-fired with the enclosure component  901  and/or other components of the electronic device  990 . For example, the haptic actuator  1051  may be formed from a first ceramic material and the enclosure component  901  may be formed from a second housing material, and the haptic actuator  1051  and the enclosure component  901  may be heated at the same time to form a co-sintered or co-fired enclosure component. In some instances, the haptic actuator  1051  and enclosure component  901  may be heated to at least partially sinter or fuse the respective ceramic materials of each element. In some instances, the one or more components of the haptic actuator  1051 , the conductive pad  1055 , the trace  1080 , and/or one or more input electrodes  1060  may be in a green, partially sintered, pre-sintered state prior to being heated together in a co-sintering or co-firing process. 
       FIG. 10C  illustrates an example partial cross-sectional view of the electronic device  990  depicted in  FIG. 9 , taken along section C-C. The electronic device  990  includes an input/output module  1050   b.  The input/output module  1050   b  includes one or more haptic actuators  1091 , and one or more input electrodes  1092 ,  1094 . In various embodiments, one or more components of the input/output module  1050   b  may be integrally formed with the wall  931 . For example, as shown in  FIG. 10C , one or more input electrodes  1092 ,  1094  may be integrally formed within the wall  931  by co-firing or co-sintering the one or more input electrodes with the enclosure component  901 . In various embodiments, one or more components of the input/output module  1050   b  may be integrally formed with the wall  931 , even if not within the wall. For example, as shown in  FIG. 10C , one or more haptic actuators  1091  may be integrally formed with the wall  931  (e.g., on the wall  931 ) by co-firing or co-sintering the one or more input electrodes with the enclosure component  901 . 
     The wall  931  defines at least a portion of an exterior surface of the enclosure  900  that is configured to receive a contact from a user. Integrally forming an input electrode within a wall of the enclosure allows for localized touch input and force input detection at select locations along the exterior surface of the enclosure. Integrally forming a haptic actuator within a wall of the enclosure allows for localized haptic output (e.g., localized deflection of the wall  931 ) at select locations along the exterior surface of the enclosure. 
     As discussed above, in various embodiments, localized haptic feedback may be provided by means of the one or more haptic actuators  1091 . A haptic actuator  1091  may be similar to the haptic actuator  1051  discussed above with respect to  FIG. 10A . The haptic actuator  1091  may include a piezoelectric element  1062 , a first electrode  1063 , and a second electrode  1064 . In some embodiments, the haptic actuator  1091  may include one or more buffer elements (e.g., a first buffer element  1096  and a second buffer element  1098 ). As previously mentioned, if the haptic actuator  1051  is formed form a ceramic (e.g., ceramic piezoelectric) material, the haptic actuator  1051  may be integrally formed with a structure of the enclosure by being co-fired or co-sintered with the wall  931  of the enclosure  900 . In some embodiments, the haptic actuators  1091  are positioned on the interior surface  1004  of the wall  931 . 
     One or more signal lines may be conductively coupled with the first electrode  1063  and/or the second electrode  1064  to transmit actuation signals to each haptic actuator  1091 . Accordingly, a potential may be applied across the piezoelectric element  1062 —a reference voltage may be provided to the second electrode  1064 ; and an actuation signal may be provided to the first electrode  1063 . In some embodiments, the first electrode  1063  may be coupled to a reference voltage and the second electrode  1064  may be coupled to an actuation signal. In various embodiments the reference voltage may be ground. In response to a drive voltage or signal, the haptic actuator  1091  may produce a localized deflection or haptic output along the wall  931 . The localized deflection or haptic output may be tactically perceptible through a touch of the user&#39;s finger or other part of the user&#39;s body. 
     Similar to the haptic actuators described above, the haptic actuator  1091  may be fixed with respect to the wall  931 . Because the piezoelectric element  1062  is fixed with respect to the wall  931 , as the piezoelectric element  1062  contracts along the plane parallel to the interior surface  1004  and/or the exterior surface  911 , the piezoelectric element  1062  may bow and deflect in a direction orthogonal to the interior surface  1004  and/or the exterior surface  911  (e.g., rightward toward the exterior surface  911  with respect to  FIG. 10C ), thereby causing the wall  931  to bow and/or deflect. The haptic feedback may be localized to a portion of the exterior surface  911  close to the haptic actuator  1091  (e.g., a portion of the exterior surface  911  rightward of the haptic actuator  1091  with respect to  FIG. 10C ). 
     The input electrodes  1092 ,  1094 ,  1099  may be similar to the input electrodes discussed herein (e.g., input electrodes  1060   a,    1060   b ). In some embodiments, the input electrodes  1092 ,  1094  may be integrally formed with the wall  931 , for example by co-firing the input electrodes with the enclosure component  901 . The input electrodes  1099  may be deposited on a buffer element, such as buffer element  1098 . 
     Each input electrode  1092 ,  1094 ,  1099  may be formed from a conductive material arranged in a pattern suitable to detect inputs. For example, the input electrodes  1092 ,  1094 ,  1099  may be arranged in spiral shapes, such as described with respect to  FIG. 10D . The input electrodes  1092 ,  1094 ,  1099  alone or in combination with other electrodes may define an array of input electrodes. In some instances, at least a portion of the array of electrodes defines a touch sensor or a portion of the touch screen that is positioned below the cover (e.g., cover  902  of  FIG. 9 ). 
       FIG. 10D  depicts an example partial cross-sectional view showing example patterns of the input electrodes  1092  taken along section E-E.  FIG. 10D  also depicts an example partial cross-sectional view showing example patterns of the input electrodes  1094  taken along section F-F. As depicted, each input electrode  1092 ,  1094 ,  1099  may be a touch- and/or strain-sensitive element  1090   a,    1090   b,  which may be a conductive trace deposited or otherwise formed on or within the wall  931 . In some embodiments, one or more input electrodes are responsive to strain and may be configured to produce an electrical signal or have an electrical characteristic (e.g., resistance) that is responsive to a force applied to the wall  931 . In some embodiments, one or more input electrodes are may be configured to produce an electrical signal or have an electrical characteristic (e.g., capacitance) that is responsive to a touch input applied along the wall  931 . 
     The arrangement and function of the input electrodes  1092 ,  1094 ,  1099  may vary depending on the implementation. In some embodiments, input electrode  1092  is a touch-sensing input electrode and input electrodes  1094  and  1099  are force-sensing input electrodes. In some embodiments, the input electrodes  1092 ,  1094  are touch-sensing and force-sensing electrodes. In some embodiments, the input/output module  1050   b  includes a subset of the input electrodes  1092 ,  1094 , and  1099 . For example, the input/output module  1050   b  may include a touch-sensing input electrode  1092  and a force-sensing input electrode  1094 . As another example, the input/output module  1050   b  may include a touch-sensing input electrode  1092  and a force-sensing input electrode  1099 . 
     In some embodiments, the input electrodes are arranged in spiral shapes, such as elements  1090   a,    1090   b  shown in  FIG. 10D . In various embodiments, the shape or geometry of an input electrode  1092 ,  1094  may vary. For example, an input electrode may be formed from a set of conductive traces arranged in a doubled-back spiral shape, a forked or comb-shaped configuration, a linear serpentine shape, a radial serpentine shape, a spiral shape, and so on. In these and other embodiments, the input electrode  1092 ,  1094  may include conductive traces set in one or more sets of parallel lines. 
     Each input electrode  1092 ,  1094  includes or is electrically coupled to one or more signal lines (e.g., one or more signal lines of a signal trace). For example, returning to  FIG. 10C , the input electrodes  1092 ,  1094  may be coupled to one or more conductive pads  1095   a,b  and  1093   a,    1060   b,  respectively. A signal generator may provide electrical signals to each input electrode  1092 ,  1094  through the signal line(s), for example via the conductive pads  1093 ,  1095 . The conductive pads  1093 ,  1095  may be formed from a conductive material deposited on the internal surface  1004  and/or integrally formed with the wall  931 . Processing circuitry may be coupled to the signal line(s) to detect a capacitive touch response and a resistive force response. That is, a presence and location of a touch input may be detected through a change in capacitance of an input electrode  1092 ,  1094 , or across multiple input electrodes  1092 ,  1094  (see  FIGS. 3B and 4B , described above). Further, an amount of force may be detected using a change in resistance through an input electrode  1092 ,  1094  to produce a non-binary force signal or output (see  FIGS. 3C and 4C , described above). 
     The conductive material of the input electrodes  1092 ,  1094  may include materials such as, but not limited to: gold, copper, copper-nickel alloy, copper-nickel-iron alloy, copper-nickel-manganese-iron alloy, copper-nickel-manganese alloy, nickel-chrome alloy, chromium nitride, a composite nanowire structure, a composite carbon structure, graphene, nanotube, constantan, karma, silicon, polysilicon, gallium alloy, isoelastic alloy, and so on. The conductive material of the input electrodes  1092 ,  1094  may be formed or deposited on a surface using a suitable disposition technique such as, but not limited to: vapor deposition, sputtering, printing, roll-to-roll processing, gravure, pick and place, adhesive, mask-and-etch, and so on. In some embodiments, the input electrodes may be co-fired with one or more components of the input/output module and/or the enclosure component  901 . 
     The signal trace may couple the input electrodes  1092 ,  1094 , the haptic actuators  1091 , and/or other components of the electronic device  990  to one or more additional components of the electronic device  990 . In some embodiments, the signal trace is coupled to processing circuitry disposed in the interior volume of the electronic device  990 . 
     In some embodiments, one or more components of the haptic actuator  1091  and/or one or more input electrodes  1092 ,  1094  may be co-fired with the enclosure component  901  and/or other components of the electronic device  990 . For example, the haptic actuator  1091  may be formed from a first ceramic material and the enclosure component  901  may be formed from a second housing material, and the haptic actuator  1091  and the enclosure component  901  may be heated at the same time to form a co-sintered or co-fired enclosure component. In some instances, the haptic actuator  1091  and enclosure component  901  may be heated to at least partially sinter or fuse the respective ceramic materials of each element. In some instances, the one or more components of the haptic actuator  1091 , the contact pad  1093 ,  1095 , and/or one or more input electrodes  1092 ,  1094  may be in a green, partially sintered, pre-sintered state prior to being heated together in a co-sintering or co-firing process. 
     In the example embodiment shown in  FIG. 10A-10B , the input/output module  1050   a  includes three haptic actuators and four input electrodes. In the example embodiment shown in  FIG. 10C-10D , the input/output module  1050   b  includes two haptic actuators and two input electrodes. These are example configurations, and in various embodiments, the input/output module (s) may include more or fewer haptic actuators and/or more or fewer input electrodes. The input/output modules  1050   a,    1050   b  are shown in  FIGS. 10A-10D  as being at least partially disposed in the wall  931  of the electronic device  990 . These are examples of placement of the input/output module. In various embodiments, the input/output module(s) may be positioned at any suitable location in an electronic device. For example, the input/output module may be positioned on or within and/or integrally formed with one or more covers of the electronic device or any other suitable components. 
     The relative position of the various layers described above may change depending on the embodiment. Some layers may be omitted in other embodiments. Other layers may not be uniform layers of single materials, but may include additional layers, coatings, and/or be formed from composite materials. For example, an insulation layer may encapsulate one or more components of the input/output module  1050   a  to protect from corrosion and/or electrical interference. As another example, the electronic device  990  may include a layer  1003  between the cover  902  and the enclosure component  901 . In various embodiments, the layer  1003  is an adhesive and/or compliant layer. In some embodiments, the layer  1003  is a gasket that forms a seal (e.g., a watertight and/or airtight seal) around a perimeter of the cover  902 . The electronic device may include additional layers and components, such as processing circuitry, a signal generator, a battery, etc., which have been omitted from  FIGS. 10A-10D  for clarity. 
     As described above, an input/output module may be disposed in any electronic device. In one embodiment, the input/output module is disposed in a wearable electronic device such as a watch.  FIG. 11  depicts an example wearable electronic device  1100  that may incorporate an input/output module as described herein. 
     In the illustrated embodiment, the electronic device  1100  is implemented as a wearable computing device (e.g., an electronic watch). Other embodiments can implement the electronic device differently. For example, the electronic device can be a smart telephone, a gaming device, a digital music player, a device that provides time, a health assistant, and other types of electronic devices that include, or can be connected to a sensor(s). 
     In the embodiment of  FIG. 11 , the wearable electronic device  1100  includes an enclosure  1150  at least partially surrounding a display  1108 , a watch crown  1110 , and one or more buttons  1112 . The wearable electronic device  1100  may also include a band  1104  that may be used to attach the wearable electronic device to a user. The display  1108  may be positioned at least partially within an opening defined in the enclosure  1150 . A cover may be disposed over the display  1108 . The wearable electronic device  1100  can also include one or more internal components (not shown) typical of a computing or electronic device, such as, for example, processing circuitry, memory components, network interfaces, and so on.  FIG. 15  depicts an example computing device, the components of which may be included in the wearable electronic device  1100 . 
     In various embodiments, the wearable electronic device  1100  may include an input/output module such as those described herein. For example, the input/output module may be positioned on or within a wall  1131 , the display  1108  and/or a cover disposed over the display, the band  1104 , the watch crown  1110 , the button  1112 , or substantially any other surface of the wearable electronic device  1100 . 
     In various embodiments, the wearable electronic device  1100  may display graphical outputs. For example, processing circuitry of the wearable electronic device may direct the display  1108  to provide a graphical output. Similarly, in some embodiments, the display  1108  is configured to receive inputs as a touch screen style display. In various embodiments, the input/output module may provide outputs and/or detect inputs in relation to graphical outputs provided at the display, inputs received at the wearable electronic device  1100 , and so on. 
       FIG. 12  depicts an example input device  1204  that may incorporate an input/output module as described herein. The input device  1204  may be used to provide input to an additional electronic device, for example, through interaction with a touch-sensitive surface. The input device  1204  may be a stylus keyboard, trackpad, touch screen, three-dimensional input systems (e.g., virtual or augmented reality input systems), or other corresponding input structure. A user may manipulate an orientation and position of the electronic device  1204  relative to the touch-sensitive surface to convey information to the additional electronic device such as, but not limited to, writing, sketching, scrolling, gaming, selecting user interface elements, moving user interface elements, and so on. The touch-sensitive surface may be a multi-touch display screen or a non-display input surface (e.g., such as a trackpad or drawing tablet) as may be appropriate for a given application. 
       FIG. 12  generally shows the input device  1204  having a long, narrow, or elongated body or enclosure  1208  coupled to the tip  1206  (although the exact shape of the stylus may widely vary). The enclosure  1208  may extend along a longitudinal axis of a stylus body or other structure having an exterior surface that is configured for manipulation by a user as a writing implement. For example, the exterior surface of the enclosure  1208  may be a hoop, shell, or other substantially cylindrical structure that may be gripped by a user in order to use the input device  1204  as a writing instrument. The tip  1206  may be configured to move relative to the enclosure  1208  in response to a force input. 
     In various embodiments, the input device  1204  may include one or more input/output modules as described herein. For example, an input/output module may be positioned on or in the enclosure  1208 , for example on or in a wall of the enclosure  1208 . The input/output module may detect inputs and/or provide haptic outputs at a surface of the input device  1204 . 
       FIG. 13  depicts an example method for detecting a location of a touch input and an amount of force corresponding to the touch input with a single module. As described above, touch input and force input may be detected through input electrodes disposed on a single layer of an input/output module of an input device, though this is not required. 
     The method begins at operation  1302 , in which an input electrode is driven by a drive signal. The input electrode may be driven by an alternating current drive signal or a direct current drive signal. In some embodiments, the input electrode may be driven by a first drive signal (e.g., a drive signal having a first waveform, which may include A/C and/or D/C components, and may have a given amplitude, shape, and/or frequency) during a first period of time, and a different second drive signal (e.g., a drive signal having a second waveform, which may include A/C and/or D/C components, and may have a given amplitude, shape, and/or frequency) during a second period of time. In some embodiments, the input device may include a set or array of input electrodes. Each input electrode may be driven by the drive signal, or some input electrodes may be driven while others are not. The input electrodes may be driven by a same drive signal, or by distinct drive signals (e.g., drive signals having different waveforms). 
     Next, at operation  1304 , the input electrode is monitored (e.g., by processing circuitry). Generally, the input electrode is monitored for a change in an electrical parameter, such as capacitance. Where the input device includes multiple input electrodes, all input electrodes may be monitored concurrently, or the input electrodes may be monitored during distinct time periods. 
     Next, at operation  1306 , a touch location is determined. As the input electrodes are monitored, a change in capacitance may be detected, indicating a finger or other object has approached or come in contact with an input surface (e.g., defined by a cover) of the input device. The location of the touch may be determined based on a location corresponding to the input electrode(s) which detected the change in capacitance. 
     Next, at operation  1308 , the input electrode is monitored for a change in another electrical parameter, such as resistance. Where the input device includes multiple input electrodes, all input electrodes may be monitored concurrently, or the input electrodes may be monitored during distinct time periods. 
     Lastly, at operation  1310 , an amount of force is determined. As the input electrodes are monitored, a non-binary change in resistance may be detected, indicating a force has been applied to the cover. A non-binary amount of the force may be estimated or determined based on the change in resistance detected. In some embodiments, a location of the force may be determined based on a location corresponding to the input electrode(s) which detected the change in resistance. 
     One may appreciate that although many embodiments are disclosed above, the operations and steps presented with respect to methods and techniques are meant as exemplary and accordingly are not exhaustive. One may further appreciate that alternate operation order or fewer or additional operations may be required or desired for particular embodiments. 
     For example,  FIG. 14  depicts another example method for detecting a location of a touch and an amount of force corresponding to the touch with a single module. 
     The method begins at operation  1402 , in which an input electrode is driven by a drive signal. The input electrode may be driven by an alternating current drive signal or a direct current drive signal. In some embodiments, the input device may include a set or array of input electrodes. Each input electrode may be driven by the drive signal, or some input electrodes may be driven while others are not. The input electrodes may be driven by a same drive signal, or by distinct drive signals (e.g., drive signals having different waveforms). 
     Next, at operation  1404 , the input electrode is monitored (e.g., by processing circuitry). Generally, the input electrode is monitored for a change in capacitance. Next, at operation  1406 , a touch location is determined. As the input electrodes are monitored, a change in capacitance may be detected, and a touch location may be determined based on a location corresponding to the input electrode(s) which detected the change in capacitance. 
     At operation  1408 , which may occur concurrently with operation  1404  and/or operation  1406 , the input electrode is monitored for a change in resistance. Lastly, at operation  1410 , which may occur concurrently with operation  1404  and/or operation  1406 , an amount of force is determined. As the input electrodes are monitored, a non-binary change in resistance may be detected, indicating a force has been applied to the cover. A non-binary amount of the force, may be estimated or determined based on the change in resistance detected. 
       FIG. 15  depicts example components of an electronic device in accordance with the embodiments described herein. The schematic representation depicted in  FIG. 15  may correspond to components of the devices depicted in  FIGS. 1-10 , described above. However,  FIG. 15  may also more generally represent other types of electronic devices with an integrated input/output module that receives touch and/or force inputs and provides localized deflection at a surface. 
     As shown in  FIG. 15 , a device  1500  includes an input electrode  1506  which detects touch and/or force inputs. The input electrode  1506  may receive signals from a signal generator  1556 , and output response signals to processing circuitry  1548 . The response signals may indicate touch inputs through changes in capacitance, and may further indicate force inputs through changes in resistance. 
     The device  1500  also includes processing circuitry  1548 . The processing circuitry  1548  is operatively connected to components of the device  1500 , such as an input electrode  1506 . The processing circuitry  1548  is configured to determine a location of a finger or touch over an input surface (e.g., defined by a cover) of the device  1500 , based on signals received from the input electrode  1506 . 
     The processing circuitry  1548  may also be configured to receive force input from the input electrode  1506  and determine a non-binary amount of force based on signals received from the input electrode  1506 . In accordance with the embodiments described herein, the processing circuitry  1548  may be configured to operate using a dynamic or adjustable force threshold. 
     In addition the processing circuitry  1548  may be operatively connected to computer memory  1550 . The processing circuitry  1548  may be operatively connected to the memory  1550  component via an electronic bus or bridge. The processing circuitry  1548  may include one or more computer processors or microcontrollers that are configured to perform operations in response to computer-readable instructions. The processing circuitry  1548  may include a central processing unit (CPU) of the device  1500 . Additionally or alternatively, the processing circuitry  1548  may include other processors within the device  1500  including application specific integrated chips (ASIC) and other microcontroller devices. The processing circuitry  1548  may be configured to perform functionality described in the examples above. 
     The memory  1550  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  1550  is configured to store computer-readable instructions, sensor values, and other persistent software elements. 
     In this example, the processing circuitry  1548  is operable to read computer-readable instructions stored on the memory  1550 . The computer-readable instructions may adapt the processing circuitry  1548  to perform the operations or functions described above with respect to  FIGS. 1-10 . The computer-readable instructions may be provided as a computer-program product, software application, or the like. 
     The device  1500  may also include a battery  1558  that is configured to provide electrical power to the components of the device  1500 . The battery  1558  may include one or more power storage cells that are linked together to provide an internal supply of electrical power. The battery  1558  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  1500 . The battery  1558 , via power management circuitry, may be configured to receive power from an external source, such as an alternating current power outlet. The battery  1558  may store received power so that the device  1500  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  1500  also includes a display  1502  that renders visual information generated by the processing circuitry  1548 . The display  1502  may include a liquid-crystal display, light-emitting diode, organic light emitting diode display, organic electroluminescent display, electrophoretic ink display, or the like. If the display  1502  is a liquid-crystal display or an electrophoretic ink display, the display may also include a backlight component that can be controlled to provide variable levels of display brightness. If the display  1502  is an organic light-emitting diode or organic electroluminescent type display, the brightness of the display  1502  may be controlled by modifying the electrical signals that are provided to display elements. 
     In some embodiments, the device  1500  includes one or more input devices  1560 . The input device  1560  is a device that is configured to receive user input. The input device  1560  may include, for example, a push button, a touch-activated button, or the like. In some embodiments, the input devices  1560  may provide a dedicated or primary function, including, for example, a power button, volume buttons, home buttons, scroll wheels, and camera buttons. Generally, an input electrode may also be classified as an input component. However, for purposes of this illustrative example, the input electrode  1506  is depicted as a distinct component within the device  1500 . 
     The device  1500  may also include a haptic actuator  1521 . The haptic actuator  1521  may be implemented as described above, and may be a ceramic piezoelectric transducer. The haptic actuator  1521  may be controlled by the processing circuitry  1548 , and may be configured to provide haptic feedback to a user interacting with the device  1500 . 
     The device  1500  may also include a communication port  1552  that is configured to transmit and/or receive signals or electrical communication from an external or separate device. The communication port  1552  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  1552  may be used to couple the device  1500  to a host computer. 
     The device  1500  may also include a signal generator  1556 . The signal generator  1556  may be operatively connected to the input electrode  1506  and the haptic actuator  1521 . The signal generator  1556  may transmit electrical signals to the haptic actuator  1521  and the input electrode  1506 . The signal generator  1556  is also operatively connected to the processing circuitry  1548 . The processing circuitry  1548  is configured to control the generation of the electrical signals for the haptic actuator  1521  and the input electrode  1506 . In some embodiments, distinct signal generators  1556  may be connected to the input electrode  1506  and the haptic actuator  1521 . 
     The memory  1550  can store electronic data that can be used by the signal generator  1556 . For example, the memory  1550  can store electrical data or content, such as timing signals, algorithms, and one or more different electrical signal characteristics that the signal generator  1556  can use to produce one or more electrical signals. The electrical signal characteristics include, but are not limited to, an amplitude, a phase, a frequency, and/or a timing of an electrical signal. The processing circuitry  1548  can cause the one or more electrical signal characteristics to be transmitted to the signal generator  1556 . In response to the receipt of the electrical signal characteristic(s), the signal generator  1556  can produce an electrical signal that corresponds to the received electrical signal characteristic(s). 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not intended 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. 
     For example, features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Further, the term “exemplary” does not mean that the described example is preferred or better than other examples.

Metadata:
Filing Date: 20210628
Publication Date: 20221004
Grant Date: 20221004
Priority Date: 20170906
Inventors: XU, QILIANG
LEHMANN, Alex J.
YU, MING
ZHAO, Xianwei
WEN, XIAONAN
WU, SHAN
NIU, XIAOFAN
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/0448", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/045", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0448", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/045", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0448", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 65518685