Patent Publication Number: US-2023152908-A1

Title: Capacitive touch panel for sensing mechanical inputs to a device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/647,583, filed Jan. 10, 2022 (published as U.S. Publication No. 2022-0129102), which is a continuation of U.S. patent application Ser. No. 14/915,224, filed Feb. 27, 2016 (issued as U.S. Pat. No. 11,221,697), which is a National Phase Application under 35 U.S.C. § 371 of International Application No. PCT/US2014/031255, filed Mar. 19, 2014, which is a continuation of International Application No. PCT/US2013/057161, filed Aug. 28, 2013, the contents of which are incorporated herein by reference in their entireties for all purposes. 
    
    
     FIELD OF THE DISCLOSURE 
     This relates generally to sensing mechanical inputs on a device, and more specifically to doing so using a capacitive touch panel on the device. 
     BACKGROUND OF THE DISCLOSURE 
     Many electronic devices have capacitive touch panels, as such panels can provide users a natural and intuitive input method. Touch panels can, for example, allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed on the touch panel. In general, touch panels can recognize a touch and the position of the touch on the touch panel, and the electronic device can then interpret the touch in accordance with the display appearing at the time of the touch, and thereafter can perform one or more actions based on the touch. In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing fields used to detect touch can extend beyond the surface of the touch panel, and objects approaching the surface may be detected near the surface without actually touching the surface. Further, some touch panels can be multi-touch panels for detecting one or more touches thereon. 
     In addition to touch panels, many electronic devices may also have mechanical inputs, such as buttons and/or switches. These mechanical inputs can control power (i.e., on/off) and volume, among other functions. However, mechanical inputs, such as buttons or rotary inputs, can have considerable component costs associated with them, as the mechanical inputs generally can include structure for providing tactile feedback to a user (e.g., the “click” of a button) and also structure for sensing an input from the mechanical input. These two structures can be complex. Further, such structures can occupy substantial volume in electronic devices, which can make it difficult to reduce the sizes of such devices. 
     SUMMARY OF THE DISCLOSURE 
     The following description includes examples of capacitively sensing mechanical inputs using a touch panel in a device. The mechanical inputs can be inputs such as linear buttons (e.g., power or volume), rotary inputs (e.g., volume knob), slide switches (e.g., hold switch or ringer switch), on/off push/push buttons, and multi-position rotary inputs (e.g., rotary version of a slide switch to select a setting), for example. In some examples, a mechanical input can be substantially electrically conductive, and the touch panel can sense an input from the mechanical input based on a capacitance measurement between the touch panel and the mechanical input. In some examples, the mechanical input can be substantially electrically insulating, and the touch panel can sense an input from the mechanical input based on a capacitance measurement between the touch panel and a sensor, where the mechanical input can be disposed between the touch panel and the sensor. In some examples, inputs from the mechanical input can be differentiated from touch inputs based on various characteristics of the touch inputs and the mechanical input (e.g., size, shape, magnitude, etc.). In some examples, the mechanical input can include one or more localized extensions to facilitate the touch panel&#39;s determination of a position of the mechanical input. In some examples, the mechanical input can include structure for providing tactile response. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  illustrates an example mobile telephone that includes a touch screen. 
         FIG.  1 B  illustrates an example digital media player that includes a touch screen. 
         FIG.  1 C  illustrates an example watch that includes a touch screen. 
         FIG.  2    illustrates an expanded view of an exemplary device according to examples of this disclosure. 
         FIG.  3    illustrates an exemplary configuration for sensing input from a button according to examples of this disclosure. 
         FIG.  4    illustrates an alternative exemplary configuration for sensing input from a button according to examples of this disclosure. 
         FIG.  5    illustrates an example configuration in which a mechanical input sensing portion can be shielded from touch activity occurring on a touch screen above by a barrier. 
         FIG.  6 A  illustrates an exemplary button having a single extension. 
         FIG.  6 B  illustrates an exemplary button having two extensions. 
         FIG.  6 C  illustrates a cross-section of an exemplary rotary input according to examples of this disclosure. 
         FIG.  7    illustrates an exemplary button for use in a capacitive mechanical input sensing environment, the button having a structure that can provide a user with tactile feedback of the button&#39;s operation. 
         FIG.  8    illustrates an exemplary configuration for detecting water or water damage in the device according to examples of this disclosure. 
         FIG.  9    illustrates an example computing system for implementing the mechanical input sensing according to examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples. 
     Some electronic devices can include both touch screens (or touch pads and the like) for sensing touch inputs, and mechanical inputs, such as buttons and/or switches. These mechanical inputs can require associated structures for providing tactile feedback to a user (e.g., the “click” of a button) and for sensing inputs from the mechanical inputs. Such associated structures can be expensive to manufacture, and can occupy substantial volume in the electronic devices, which can make it difficult to reduce the sizes of such devices. The above cost and volume concerns can be alleviated by configuring the touch screens/touch pads in electronic devices to couple to and sense not only touch inputs from a user, but also to couple to and sense mechanical inputs, such as buttons, inside the devices. In this way, the associated structures that can be required for a mechanical input can be simplified, reduced or eliminated. Additionally, using touch screens/touch pads to sense mechanical inputs can decouple the structures used to provide tactile feedback to a user from the structures used for the actual sensing of the mechanical inputs. As such, the physical profile of the tactile response of a button, for example, can be tuned independently from, and without changing, the performance of the button&#39;s input detection. Note that although this specification may primarily refer to touch screens for convenience, it should be understood that the various examples of this disclosure include other touch-sensitive surfaces such as touch pads, trackpads and the like. 
       FIGS.  1 A- 1 C  show example systems in which mechanical input sensing according to examples of the disclosure may be implemented.  FIG.  1 A  illustrates an example mobile telephone  136  that includes touch screen  124 .  FIG.  1 B  illustrates an example digital media player  140  that includes touch screen  126 .  FIG.  1 C  illustrates an example watch  144  that includes touch screen  128 . Touch screens  124 ,  126  and  128  may be based on, for example, self capacitance or mutual capacitance, or another touch sensing technology. For example, in a self capacitance based touch system, an individual electrode with a self-capacitance to ground can be used to form a touch pixel (touch node) for detecting touch. As an object approaches the touch pixel, an additional capacitance to ground can be formed between the object and the touch pixel. The additional capacitance to ground can result in a net increase in the self-capacitance seen by the touch pixel. This increase in self-capacitance can be detected and measured by a touch sensing system to determine the positions of one or more objects when they touch the touch screen. A mutual capacitance based touch system can include, for example, drive regions and sense regions, such as drive lines and sense lines. For example, drive lines can be formed in rows while sense lines can be formed in columns (i.e., drive lines and sense lines can be orthogonal). Touch pixels (touch nodes) can be formed at the intersections or adjacencies (in single layer configurations) of the rows and columns. During operation, the rows can be stimulated with an AC waveform and a mutual capacitance can be formed between the row and the column of the touch pixel. As an object approaches the touch pixel, some of the charge being coupled between the row and column of the touch pixel can instead be coupled onto the object. This reduction in charge coupling across the touch pixel can result in a net decrease in the mutual capacitance between the row and the column and a reduction in the AC waveform being coupled across the touch pixel. This reduction in the charge-coupled AC waveform can be detected and measured by the touch sensing system to determine the positions of one or more objects when they touch the touch screen. In some examples, a touch screen can be multi-touch, single touch, projection scan, full-imaging multi-touch, or any capacitive touch. 
       FIG.  2    illustrates an expanded view of an exemplary device  200  according to examples of this disclosure. Device  200  can be any of mobile telephone  136 , digital media player  140 , watch  144 , or any other wearable and/or electronic device. Device  200  can include touch screen  206  surrounded by border region  208 . Border region  208  can be a region between touch screen  206  and the edge of device  200 . In some examples, device  200  may not have border region  208 , and may instead have a surface composed only of touch screen  206 . Device  200  can also include mechanical inputs such as button  202 , slide switch  203  and rotary input  204 . Button  202  can be, for example, a linear button, which, in operation, can slide into and out of device  200  in a linear fashion. Rotary input  204  can be, for example, a knob. Slide switch  203  can be, for example, a switch that slides vertically along the edge of device  200 . Button  202 , slide switch  203  and rotary input  204  can be actuated by a user to interact with device  200  in various ways. For example, rotary input  204  can be a volume knob by which a user can increase or decrease a volume output by speakers that can be included in device  200 . Button  202  can be a power button by which a user can turn device  200  on or off. Slide switch  203  can be a slide switch for muting the device. Button  202 , slide switch  203  and rotary input  204  are provided by way of example only. It is understood that device  200  can include fewer or more mechanical inputs than the ones illustrated. It is further understood that device  200  can include mechanical inputs other than buttons, slide switches or rotary inputs, such as on/off push/push buttons and multi-position rotary inputs (e.g., rotary version of a slide switch to select a setting), for example. Other types of mechanical inputs are also within the scope of this disclosure. 
       FIG.  3    illustrates an exemplary configuration  300  for sensing input from button  302  according to examples of this disclosure. The illustration of  FIG.  3    can be that of a cross-section A-A′ of device  200  of  FIG.  2   . Configuration  300  can include display layer  310 , touch layer  304  and cover glass (or plastic)  308 . Display layer  310  can be one or more layers of electronics for displaying images on touch screen  306 . Touch layer  304  can be one or more layers of electronics for sensing touch on touch screen  306 . Cover glass  308  can be one or more layers for protecting touch layer  304  and/or display layer  310  from, for example, a user&#39;s touch on touch screen  306 . Although illustrated as three separate layers, it is understood that cover glass  308 , touch layer  304  and display layer  310  can be fabricated as a single layer, or can be fabricated as two separate layers or four or more separate layers. For example, display layer  310  and touch layer  304  can be fabricated as one layer, and cover glass  308  can be fabricated as a separate layer. For ease of description, the examples of the disclosure will assume that display layer  310 , touch layer  304  and cover glass  308  are separate layers, as illustrated. 
     Button  302  can be a linear button, as described above. Further, part of button  302  can extend under mechanical input sensing portion  312  of touch layer  304 . Mechanical input sensing portion  312  can be a portion of touch layer  304  that can be used to capacitively sense mechanical inputs. Button  302  can be substantially electrically conductive so as to allow for capacitive sensing of the button by mechanical input sensing portion  312 . Mechanical input sensing portion  312  can capacitively sense the extension of button  302  in a similar manner as described above with respect to  FIGS.  1 A- 1 C , except that instead of sensing changes in capacitance due to touches on touch screen  306  from above, the mechanical input sensing portion can capacitively sense changes in capacitance due to movements of button  302  from below. In particular, as button  302  extends into mechanical input sensing portion  312 , the mechanical input sensing portion can sense changes in capacitance due to the extension of the button. As button  302  retracts from mechanical input sensing portion  312 , the mechanical input sensing portion can similarly sense changes in capacitance due to the retraction of the button. A device that incorporates configuration  300  can determine position information for button  302  (i.e., whether the button is depressed) based on the above capacitance measurements. The position information determined can be binary (i.e., whether button  302  is depressed or is not depressed) or can be continuous (i.e., the degree to which the button is depressed). Button  302  can be placed close to mechanical input sensing portion  312  of touch layer  304  to maximize sensing performance, as capacitive effects between the mechanical input sensing portion and the button can generally be inversely proportional to the distance between the mechanical input sensing portion and the button. 
     Although mechanical input sensing portion  312  is illustrated as being outside of touch screen  306  and display layer  310 , it is understood that the mechanical input sensing portion can be located inside the boundaries of the display layer and the touch screen (i.e., the mechanical input sensing portion can be dual-purpose for sensing both touch inputs from above and button  302  from below). Various ways to differentiate between touch inputs from above and mechanical inputs from below will be described later. In some examples, mechanical input sensing portion  312  can be specifically designed for sensing mechanical inputs such as button  302 . In some examples, mechanical input sensing portion  312  can be fabricated using the same fabrication process and the same layers as touch layer  304 . In some examples, mechanical input sensing portion  312  can be fabricated using a different fabrication process than that used to fabricate touch layer  304 . In some examples, mechanical input sensing portion  312  can be positioned so as to minimize or reduce interference with normal touch sensing on touch screen  306  (e.g., the mechanical input sensing portion can be positioned sufficiently far away from the rest of touch layer  304 ). With respect to the examples disclosed above, for ease of description, the examples of this disclosure will be described using the structure illustrated in  FIG.  3   , although it is understood that the scope of this disclosure is not so limited. 
       FIG.  4    illustrates an alternative exemplary configuration  400  for sensing input from button  402  according to examples of this disclosure. Configuration  400  of can be substantially that of  FIG.  3   , except for the addition of lower sensor  414  below button  402 . Button  402  can be disposed between lower sensor  414  and mechanical input sensing portion  412  of touch layer  404 . In this configuration, instead of sensing the movement of button  402  using only mechanical input sensing portion  412 , the movement of the button can be sensed by measuring changes in capacitance between the mechanical input sensing portion and lower sensor  414 . Button  402 , in this instance, can be composed of a substantially electrically insulating material, such as a dielectric, so as to allow for capacitance measurements to be performed between mechanical input sensing portion  412  and lower sensor  414 . 
     In operation, as button  402  extends into the space between mechanical input sensing portion  412  and lower sensor  414 , the capacitance between the mechanical input sensing portion and the lower sensor can change. This change in capacitance can be a result of a difference between a dielectric constant of the material of which button  402  is composed and a dielectric constant of the unoccupied space between mechanical input sensing portion  412  and lower sensor  414 . Based on the above change in capacitance, the device can determine if and how far button  402  has been depressed into mechanical input sensing portion  412 . 
     In the detection schemes described above, it can be helpful to isolate changes in capacitance sensed by the mechanical input sensing portion that are a result of activity from above (e.g., user touches on the touch screen) from those that are a result of activity from below (e.g., changes in position of a mechanical input). In some examples, the mechanical inputs can be designed such that their movements can result in changes in capacitance that differ by a large amount from changes in capacitance due to touch activities (e.g., ten times larger/smaller). For example, if button  302  and mechanical input sensing portion  312  are configured such that changes in capacitance due to movements of button  302  are at least ten times smaller than changes in capacitance due to touch activity on touch screen  306  from above, the device can identify small capacitance changes as being related to button input activity, and large capacitance changes as being related to touch activity. This ratio of 10:1 is provided by way of example only. Other differences in scale can be suitable for mechanical input detection as described in this disclosure. In some examples, mechanical input sensing portion  312  can be specifically designed to be sensitive to such differences in scale. 
     In some examples, capacitances related to mechanical inputs and capacitances related to touch activity can be differentiated based on the respective “sizes” (shape and/or area) of their capacitive “footprints.” For example, button  302  can be designed to be smaller than the size of a typical contact on touch screen  306  resulting from a touch input. By doing so, when the device senses a “small sized” capacitance measurement (i.e., a capacitance measurement related to button  302 ), it can determine that it is sensing changes in capacitance due to the button, and not touch activity. In contrast, when the device senses a capacitance measurement with a size on the order of a typical touch contact resulting from touch input activity, the device can determine that it is sensing changes in capacitance due to touch inputs, and not button  302 . The size of a capacitive footprint can be determined based on how many touch sensors or pixels on the touch screen have detected the presence of the touch or mechanical input. The description above is provided by way of example only, and it is understood that the capacitive “footprints” of the mechanical inputs can be designed to be larger, instead of smaller, than the capacitive “footprints” of typical touch activity. In other related examples, the shape of the capacitive footprint can also be used to determine whether a touch or mechanical input event has been detected. For example, an ellipsoidal footprint can be determined to be a touch, while a narrow rectangular footprint can be determined to be a mechanical input event. In some examples, mechanical input sensing portion  312  can be specifically designed to sense the above sizes and/or shapes. For example, the capacitive sensing pixel density in the area responsible for sensing the mechanical input can be made higher to enable higher-resolution sensing of the mechanical input and its size and/or shape. Such design of mechanical input sensing portion  312  can be utilized in other examples of this disclosure as well. 
     In some examples, capacitive detection of mechanical inputs can be performed in a dedicated area of the touch panel; for example, in an area outside of the display area of the touch screen. This dedicated area can be positioned such that touch input activity on the touch screen from above can have substantially little effect on capacitances measured by the dedicated area from below. For example, the dedicated area (e.g., mechanical input sensing portion  312 ) can be placed outside the edge of touch screen  306 . All capacitance measurements sensed by mechanical input sensing portion  312  can be identified as measurements of mechanical inputs (e.g., button  302 ). 
     In some examples, the region of the touch layer that is used for sensing mechanical inputs can be shielded from touch activity occurring on the touch screen above by a barrier.  FIG.  5    illustrates an example configuration  500  in which mechanical input sensing portion  512  can be shielded from touch activity occurring on touch screen  506  above by barrier  516 . The configuration in  FIG.  5    can be substantially that of  FIGS.  3 - 4   , though the configuration of  FIG.  3    is illustrated by way of example, and it is understood that the scope of this disclosure is not limited to the configuration of  FIG.  3   . Barrier  516  can be positioned above mechanical input sensing portion  512  of touch layer  504  so as to shield the mechanical input sensing portion from touch activity that may occur on touch screen  506 . Barrier  516  can be any substantially electrically conductive material, such as various metals. Such an electrically conductive material can act as a capacitor in series between a user&#39;s fingers and mechanical input sensing portion  512 , and can make interference from touch activity on touch screen  506  more uniform and easier to filter. Barrier  516  can also be a material with a lower dielectric constant than cover glass  508  (e.g., air), or can simply be a larger gap between the surface of the cover glass and mechanical input sensing portion  512 , so as to reduce capacitive effects on the mechanical input sensing portion due to touch activity on touch screen  506 . Barrier  516  can also be any combination of the above. 
     By placing barrier  516  as illustrated, changes in capacitance that may be measured by mechanical input sensing portion  512  can be primarily those due to movements of button  502 . The particular positioning of barrier  516  is provided by way of example only. It is understood that barrier  516  or other structures can be positioned in other ways so as to substantially shield mechanical input sensing portion  512  from touch activity on touch screen  506 . 
     In some examples, it can be useful to be able to sense localized singularities (e.g., peaks or valleys) in mechanical input capacitance measurements to be able to more accurately determine the positions of the mechanical inputs.  FIGS.  6 A- 6 C  illustrate various configurations of mechanical inputs with localized extensions to aid in determining the positions of the mechanical inputs.  FIG.  6 A  illustrates an exemplary button  602  having a single extension  608 . Button  602  can be substantially the same as button  302  in  FIG.  3  or  4   , except that the button can include extension  608 . Extension  608  can be composed of the same material (or a similar material) as the rest of button  602 . In particular, in the mode of operation illustrated in  FIG.  3   , extension  608  can be a substantially electrically conductive material; in the mode of operation illustrated in  FIG.  4   , extension  608  can be a substantially electrically insulating material. 
     Extension  608  can provide a peak at a defined position in the capacitance measured by the mechanical input sensing portion of the touch layer of the device. For example, because extension  608  can be closer to the mechanical input sensing portion as compared with the rest of button  602 , the capacitance measured at the location of the extension can be greater than the capacitance measured at other locations on the button (i.e., the extension can create a peak in the capacitance profile measured by the mechanical input sensing portion). The device can identify this peak and its corresponding location. Therefore, the device can substantially identify a particular position at which extension  608  exists, and can determine the input state of button  602  based on the particular position. In this example, extension  608  can be placed near the end of button  602  to provide a location for the end of the button, however it is understood that the extension can be placed at different locations based on the desired operation of the button. 
       FIG.  6 B  illustrates an exemplary button  604  having two extensions  608 . In some examples, it can be useful to have a two-stage linear button: one level of depression being identified as one input to the device, and a second level of depression being identified as another input to the device. A two-stage linear button can be realized by including, for example, two extensions  608  at two different positions on button  604 . If the device senses a first peak associated with the first extension  608  (i.e., the extension on the end of button  604 ), it can interpret the sensing of the first peak as being indicative of the first stage of the button having been actuated. If the device senses a second peak associated with the second extension  608  (i.e., the extension in the middle section of button  604 ), it can interpret the sensing of the second peak as being indicative of the second stage of the button having been actuated. Accordingly, a two-stage capacitively sensed mechanical button can be realized. The positioning of the first and second extensions  608  in  FIG.  6 B  is provided by way of example only, and it is understood that other positions can be suitable for use in buttons and other mechanical inputs as well, or in buttons with more than two stages. 
       FIG.  6 C  illustrates a cross-section of an exemplary rotary input  606  according to examples of this disclosure. Rotary input  606  can rotate around axis  610 . Rotary input can include one or more extensions  608  around its periphery; in this case, the rotary input can include four extensions. As rotary input  606  rotates, peaks in capacitance corresponding to extensions  608  can appear and subside as the extensions move closer to, and further away from, the mechanical input sensing portion of the device. As each peak appears in the capacitance measured by the mechanical input sensing portion, the device can determine that rotary input  606  has been rotated by an amount equivalent to the rotational distance between adjacent extensions  608  on the rotary input, and the device can process the input accordingly (e.g., the device can increase the volume of its speakers by one “unit” amount). Each subsequent appearance of a peak can be processed similarly. The device can also determine the direction from which the peaks appear and the direction towards which the peaks subside, and the device can therefore determine the direction of rotation of rotary input  606 . This direction determination can identify whether a user is increasing or decreasing the volume on the device, for example. 
     Although the examples above have been provided with reference to button and rotary inputs, it is understood that the disclosed extensions can be similarly utilized in other types of mechanical inputs, for example, slide switches (e.g., hold switch or ringer switch), on/off push/push buttons, and multi-position rotary inputs (e.g., rotary version of a slide switch to select a setting). 
     Because the capacitive sensing schemes of this disclosure can decouple the design and incorporation of structures that provide tactile response from structures that perform mechanical input sensing, various mechanical structures can be added to the mechanical inputs to provide the desired tactile feedback with substantially no regard for how those structures may impact sensing performance of the mechanical inputs. This tactile feedback can be realized by various techniques that can be substantially independent of the sensing of the mechanical inputs, because the sensing can be done capacitively, as described above.  FIG.  7    illustrates exemplary button  702  for use in a capacitive mechanical input sensing environment, the button having a structure that can provide a user with tactile feedback of the button&#39;s operation. The configuration of button  702  can be substantially that of button  604  in  FIG.  6 B . It is understood that the configuration of button  702  is provided by way of example only, and that the examples of this disclosure can be applied to other types of mechanical inputs, such as other button designs or scroll wheels. 
     The end of button  702  can be positioned next to dome  706 , which can be anchored on bracket  704 . Dome  706  can be any structure that can provide resistance or tactile feedback to button  702 , as will be described below. A dome is provided by way of example only, and it is understood that other structures may be suitable for use in the examples of this disclosure. Bracket  704  can be any structure that can provide structural support for dome  706 . As button  702  is depressed towards bracket  704 , dome  706  can provide tactile feedback as to how much the button has been depressed, similar to the tactile feedback provided by a standard mechanical button. For example, dome  706  can provide higher resistance as button  702  is depressed more. Additionally or alternatively, dome  706  can provide a “clicking” noise or feeling once button  702  has been depressed to a specified position. The exemplary tactile feedback described above can occur while the position of button  702  can be sensed capacitively, as described above. Therefore, the tactile feedback of button  702  can be decoupled from the sensing of the depression of the button, and the one or more structures used to provide tactile feedback can be designed substantially independently from any structures used for sensing of the input from the button, which can provide potential design flexibility and space savings. It is understood that the resistance and “clicking” tactile responses described above are provided by way of example only, and that structures that provide other tactile responses are also within the scope of this disclosure. 
     In addition to decoupling the sensing of button  702  and its tactile response, the mechanical input detection of this disclosure can be beneficial in improving the waterproofing performance of a device according to examples of this disclosure. Waterproofing a device with a conventional mechanical button, for example, can be difficult because of the various structures that can be necessary for the button&#39;s operation, as described above. These sometimes complicated structures can require mechanical penetration of a waterproofing seal (e.g., by a wire needed to mechanically sense a mechanical input), which can jeopardize the integrity of the waterproofing seal, potentially causing leaks. In some examples of this disclosure, the device and its associated electronics can be in a waterproofed area. The exemplary tactile feedback structures described above can be positioned outside of the waterproofed area (as these structures need not be waterproofed in some examples), and an input from a mechanical input (e.g., a button) can be capacitively sensed through a sealed interface. In this way, mechanical penetration of the sealed interface, by for example a wire for mechanically sensing a mechanical input, can be avoided, and the structural integrity of the waterproofed area can be maintained. 
     In addition to sensing mechanical inputs, capacitance measurements as described above can be used to detect the presence of a component (e.g., SIM card, SIM tray, lanyard, audio jack connector or other connector) in the device of this disclosure. It is understood that such component detection can be realized in a manner similar to that described above for mechanical input detection (e.g., instead of sensing a button, a portion of the touch panel can be used to sense the presence of a SIM tray). 
     Capacitance measurements can also be used to detect the presence of water in the device of this disclosure, or to detect corrosion resulting from water damage to the device.  FIG.  8    illustrates an exemplary configuration  800  for detecting water or water damage in the device according to examples of this disclosure. Configuration  800  can be an edge region of the device where cover glass (or plastic)  808  can be secured to the device by frame  802 . For ease of description, no touch layer or display layer is illustrated in  FIG.  8   , but it is understood that such layers can exist as part of, or attached to, cover glass  808 . Gap  804  can exist between frame  802  and cover glass  808 . Gap  804  can exist for various reasons; for example, manufacturing reasons and/or by design. Gap  804  can be an air gap, or it can be filled with one or more materials. The following description will be provided assuming that gap  804  is an air gap. 
     Electrode  810  can be positioned on the bottom surface of cover glass  808 , and electrode  812  can be positioned on an adjacent top surface of frame  802 . Electrodes  810  and  812  can be positioned opposite each other so as to allow for a capacitance measurement to be taken between the two, and the electrodes can be substantially parallel to each other. 
     Under normal operating conditions (i.e., no water present and no water damage), the capacitance measured between electrodes  810  and  812  can be substantially that of a parallel plate capacitor having air as the dielectric between its two plates. If water enters gap  804 , the capacitance between electrodes  810  and  812  can change, because the dielectric constant of water can be different than the dielectric constant of air. When the device senses this change in capacitance between electrodes  810  and  812 , it can identify that water has entered the device through gap  804 . In addition to sensing water, the device can also sense other substances that may be occupying gap  804 . In particular, the device can calculate the dielectric constant of the substances based on the capacitance measured between electrodes  810  and  812 , and can map the calculated dielectric constant to those of known substances. 
     In some examples, water, or some other substance, may not currently exist in gap  804  between electrodes  810  and  812 , but may have previously existed in the gap. In some examples, the device can sense this previous existence of water in gap  804 . For example, water may have caused corrosive damage to either or both of electrodes  810  and  812 . In such a scenario, the capacitance sensed between electrodes  810  and  812  can be affected by the corrosion of one or both of those electrodes. The device can determine, based on the changed capacitance, that water damage, such as corrosion, has occurred. Configuration  800  is provided by way of example only, and it is understood that other configurations may be suitable for water and water damage detection, and are equally within the scope of this disclosure. Further, the device can include logic coupled to electrodes  810  and  812  for measuring the capacitance between the electrodes, and for determining whether damage, such as water damage, has occurred. 
     The above-described scheme for detecting water and corrosion can also be applied to the structures of this disclosure that are directed to sensing mechanical inputs. For example, corrosion or water on or near button  302  can be sensed by mechanical input sensing portion  312  of touch layer  304  in a manner similar to that described above with reference to FIG.  8 . The configuration of  FIG.  4    can similarly be used for water and/or corrosion detection, as described above. Further, it is understood that such water and/or corrosion detection, though described here with reference to a button, can be performed with other types of mechanical inputs as well. 
       FIG.  9    illustrates an example computing system  900  for implementing the mechanical input sensing according to examples of the disclosure. Computing system  900  can be included in, for example, mobile telephone  136 , media player  140 , watch  144  or any mobile or non-mobile computing device and/or wearable device that includes a touch screen, or more generally, a touch-sensitive surface. Computing system  900  can include a touch sensing system including one or more touch processors  902 , touch controller  906  and touch screen  904 . Touch screen  904  can be a touch screen adapted to sense both touch inputs and mechanical inputs  908 , as described in this disclosure. Touch controller  906  can include circuitry and/or logic configured to sense both touch inputs and mechanical inputs  908  on touch screen  904 . In some examples, touch controller  906  and touch processor  902  can be integrated into a single application specific integrated circuit (ASIC). 
     Computing system  900  can also include host processor  928  for receiving outputs from touch processor  902  and performing actions based on the outputs. Host processor  928  can be connected to program storage  932 . For example, host processor  928  can contribute to generating an image on touch screen  904  (e.g., image of a user interface (UI)), and can use touch processor  902  and touch controller  906  to detect one or more touches on or near touch screen  904 . Host processor  928  can also contribute to sensing and/or processing mechanical inputs  908  using touch screen  904 , as described in this disclosure. The touch and/or mechanical inputs  908  can be used by computer programs stored in program storage  932  to perform actions in response to the touch and/or mechanical inputs. For example, touch inputs can be used by computer programs stored in program storage  932  to perform actions that can include moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, placing a telephone call, and other actions that can be performed in response to touch inputs. Mechanical inputs  908  can be used by computer programs stored in program storage  932  to perform actions that can include changing a volume level, locking the touch screen, turning on the touch screen, taking a picture, and other actions that can be performed in response to mechanical inputs. Host processor  928  can also perform additional functions that may not be related to touch and/or mechanical input processing. 
     Therefore, according to the above, some examples of the disclosure are directed to a device comprising a mechanical input, and a touch-sensitive surface configured to detect one or more touch inputs and an input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch-sensitive surface comprises a first portion for detecting at least the one or more touch inputs, and a second portion for detecting at least the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch-sensitive surface comprises a first portion for detecting at least the one or more touch inputs and the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the mechanical input comprises an electrically conductive material, and detecting the input from the mechanical input comprises detecting the input from the mechanical input based on one or more capacitance measurements between the mechanical input and the touch-sensitive surface. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the device further comprises a sensing element, wherein the mechanical input comprises an electrically insulating material and is disposed between the touch-sensitive surface and the sensing element, and detecting the input from the mechanical input comprises detecting the input from the mechanical input based on one or more capacitance measurements between the touch-sensitive surface and the sensing element. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the device further comprises a barrier, wherein the barrier at least partially shields the second portion from the one or more touch inputs. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the device further comprises logic, the logic configured to differentiate between the one or more touch inputs and the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, differentiating comprises differentiating between the one or more touch inputs and the input from the mechanical input based on a difference in magnitude of a capacitance measurement associated with the one or more touch inputs and a capacitance measurement associated with the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, differentiating comprises differentiating between the one or more touch inputs and the input from the mechanical input based on a difference in size of a capacitance measurement associated with the one or more touch inputs and a capacitance measurement associated with the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the mechanical input comprises one or more extensions, and the touch-sensitive surface is further configured to detect a position of each of the one or more extensions. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the device further comprises a structure for providing a tactile response for the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the device further comprises a removable component, wherein the touch-sensitive surface is further configured to detect a presence of the removable component. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch-sensitive surface is further configured to detect damage to the device. 
     Some examples of the disclosure are directed to a device comprising a first electrode, a second electrode, and logic coupled to the first electrode and the second electrode, wherein the logic is configured to detect damage to the device based on a capacitance measurement between the first electrode and the second electrode. 
     Some examples of the disclosure are directed to a method comprising detecting an input from a mechanical input using a touch-sensitive surface, the touch-sensitive surface configured to detect the input from the mechanical input and one or more touch inputs. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch-sensitive surface comprises a first portion for detecting at least the one or more touch inputs, and a second portion for detecting at least the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch-sensitive surface comprises a first portion for detecting at least the one or more touch inputs and the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the mechanical input comprises an electrically conductive material, and detecting the input from the mechanical input comprises detecting the input from the mechanical input based on one or more capacitance measurements between the mechanical input and the touch-sensitive surface. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the mechanical input comprises an electrically insulating material and is disposed between the touch-sensitive surface and a sensing element, and detecting the input from the mechanical input comprises detecting the input from the mechanical input based on one or more capacitance measurements between the touch-sensitive surface and the sensing element. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a barrier at least partially shields the second portion from the one or more touch inputs. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises differentiating between the one or more touch inputs and the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, differentiating comprises differentiating between the one or more touch inputs and the input from the mechanical input based on a difference in magnitude of a capacitance measurement associated with the one or more touch inputs and a capacitance measurement associated with the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, differentiating comprises differentiating between the one or more touch inputs and the input from the mechanical input based on a difference in size of a capacitance measurement associated with the one or more touch inputs and a capacitance measurement associated with the input from the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the mechanical input comprises one or more extensions, the method further comprising detecting a position of each of the one or more extensions. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises providing a tactile response for the mechanical input. 
     Although examples of this disclosure have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of examples of this disclosure as defined by the appended claims.