PATENT DOCUMENT

Publication Number: US-10782818-B2
Application Number: US-201816116785-A
Country: US
Kind Code: B2

Title: Load cell array for detection of force input to an electronic device enclosure

Abstract:
A force input sensor includes a load cell to adapt a compressive force applied to the force input sensor into a strain experienced by a strain sensor in the load cell. In particular, the load cell includes two compression plates separated from one another by a gap so as to define a volume between them. A flexible substrate (a “diaphragm”)—includes a strain sensor and is disposed and supported within the volume. One of the two compression plates includes a feature (a “loading feature”) that extends toward a central region of the flexible substrate. As a result of this construction, when the compression plates receive a compressive force, the loading feature induces a bending moment in the flexible substrate, thereby straining the strain sensor.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 an enclosure comprising:
 an interior sidewall surface; and 
 an exterior sidewall surface opposite the interior sidewall surface and configured to receive a force input from a user of the electronic device; and 
 a force input sensor coupled to the interior sidewall surface and comprising:
 a first compression plate coupled to the interior sidewall surface; 
 a second compression plate separated from the first compression plate so as to define a volume between the first compression plate and the second compression plate; 
 a pair of supports extending into the volume from opposite ends of the first compression plate; 
 a strain concentrator having a curved profile comprising a maxima extending into the volume from the second compression plate; 
 a flexible substrate disposed within the volume between the first compression plate and the second compression plate, the flexible substrate comprising:
 a first side coupled to the pair of supports; and 
 a second side in contact with the maxima of the curved profile of the strain concentor; 
 
 a first strain sensor disposed on the first side of the flexible substrate opposite the maxima of the curved profile of the strain concentor; and 
 a second strain sensor disposed on the second side of the flexible substrate between the maxima of the curved profile of the strain concentor and one of the pair of supports; wherein: 
 
 the force input sensor permits the first compression plate to move toward the second compression plate in response to the force input applied normal to the exterior sidewall surface; and 
 the strain concentrator induces a bending moment in the flexible substrate, tensing the first strain sensor and compressing the second strain sensor, in response to the first compression plate moving toward the second compression plate. 
 
 
     
     
       2. The electronic device of  claim 1 , further comprising a flexible spacer disposed between the first compression plate and the second compression plate, the flexible spacer configured to deform in response to the force input thereby permitting the first compression plate to move toward the second compression plate. 
     
     
       3. The electronic device of  claim 1 , wherein the strain concentrator is formed integrally with the second compression plate. 
     
     
       4. The electronic device of  claim 1 , wherein the pair of supports are formed integrally with the first compression plate. 
     
     
       5. The electronic device of  claim 1 , wherein the strain concentrator comprises a shim coupled to the second compression plate. 
     
     
       6. The electronic device of  claim 1 , wherein the strain concentrator comprises a cured adhesive. 
     
     
       7. The electronic device of  claim 1 , wherein at least one support of the pair of supports comprises a shim coupled to the first compression plate. 
     
     
       8. The electronic device of  claim 1 , further comprising a stiffener coupled to the first side of the flexible substrate. 
     
     
       9. The electronic device of  claim 8 , wherein the stiffener comprises a cutout aligned with the first strain sensor. 
     
     
       10. An electronic device enclosure configured to receive a force input, the electronic device enclosure comprising:
 an exterior surface configured to receive the force input; 
 an interior surface opposite the exterior surface; 
 a loading feature having a curved profile defining a maxima extending from the interior surface; 
 a structure separated from the interior surface and defining a support offset from the loading feature; 
 a flexible substrate contacting the maxima of the loading feature and coupled to the support; 
 a first strain sensor disposed on the flexible substrate opposite with the loading feature; and 
 a second strain sensor disposed on the flexible substrate between the loading feature and the support; wherein: 
 the interior surface moves in response to the force input, thereby causing the loading feature to induce a bending moment in the flexible substrate and induce a tension in the first strain sensor and a compression in the second strain sensor. 
 
     
     
       11. The electronic device enclosure of  claim 10 , comprising a frame defining the interior surface and the exterior surface. 
     
     
       12. The electronic device enclosure of  claim 11 , wherein the frame is formed from stainless steel. 
     
     
       13. The electronic device enclosure of  claim 11 , wherein the frame defines an exterior sidewall surface of the enclosure. 
     
     
       14. The electronic device enclosure of  claim 10 , wherein the first strain sensor is disposed on the flexible substrate offset from the loading feature. 
     
     
       15. The electronic device enclosure of  claim 10 , further comprising a foam spacer disposed between the interior surface and the structure. 
     
     
       16. The electronic device enclosure of  claim 10 , further comprising a foam spacer disposed between the structure and the flexible substrate.

Description:
FIELD 
     Embodiments described herein relate to a user input system for an electronic device, and, in particular, to a force input sensor configured to detect force input provided to an electronic device enclosure resistant to local elastic deformation. 
     BACKGROUND 
     An input sensor for an electronic device can detect when a user applies a force—generally referred to as a “force input”—to a surface of that electronic device. Such sensors, together with associated circuitry and structure, can be referred to as “force input sensors.” 
     A conventional force input sensor can be coupled to an interior sidewall of an electronic device enclosure to detect a local deformation of the enclosure resulting from a force input applied to an exterior side or edge of the enclosure. However, many electronic device enclosures are formed from a material resistant to local elastic deformation, such as stainless steel, sapphire, ceramic, glass, structured metal, structured plastic, and so on. In other examples, a user of an electronic device may prefer to protect the electronic device with a case that diffuses any force input applied across a large area. In these and related examples, a conventional force input sensor is unable to accurately quantify force input applied to an external side or edge of the electronic device enclosure because the deformation of the enclosure is too small to be detected. 
     SUMMARY 
     Embodiments described herein reference an electronic device including an enclosure. The enclosure has an interior sidewall opposite an exterior sidewall. The exterior sidewall is configured to receive a force input. The electronic device includes a force input sensor coupled to the interior sidewall. A second compression plate of the force input sensor is separated from a first compression plate by a gap so as to define a volume between the first compression plate and the second compression plate. The electronic device also includes a pair of supports extending into the volume from opposite ends of the first compression plate. The electronic device also includes a strain concentrator extending into the volume from the second compression plate. A flexible substrate is disposed within the volume between the first compression plate and the second compression plate. The flexible substrate includes a first side coupled to the pair of supports and a second side interfacing the strain concentrating feature. A strain sensor is disposed on the second side of the flexible substrate. As a result of this configuration and construction, the force input sensor permits the first compression plate to move toward the second compression plate in response to the force input applied to the exterior sidewall of the enclosure. In response to the movement, the strain concentrator induces a bending moment in the flexible substrate, straining the strain sensor. 
     Further embodiments described herein reference an electronic device enclosure. The enclosure includes an exterior surface configure to receive a force input and an interior surface opposite the exterior surface. A loading feature extends from the interior surface. A structure is separated from the interior surface and defines a support. A flexible substrate contacts the loading feature and is coupled to the support. The enclosure also includes a strain sensor disposed on the flexible substrate. As a result of this configuration and construction, the interior surface is able to move in response to the force input, causing the loading feature to induce a bending moment in the flexible substrate inducing a strain in the strain sensor. 
     Still further embodiments described herein reference method for manufacturing a force input sensor for an enclosure of an electronic device. The method includes the operations of: defining a loading feature on a first compression plate; defining a support feature on a second compression plate; coupling a flexible substrate (with a strain sensor) to the support feature of the second compression plate; aligning the loading feature of first compression plate with the strain sensor of flexible substrate; and coupling the first compression plate to the second compression plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to representative embodiments illustrated in the accompanying figures. It should be understood that the following descriptions are not intended to limit this disclosure to one included embodiment. To the contrary, the disclosure provided herein is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the described embodiments, and as defined by the appended claims. 
         FIG. 1  depicts an electronic device having an enclosure incorporating a force input sensor, such as described herein. 
         FIG. 2A  depicts a simplified cross-section of the force input sensor of  FIG. 1 , taken through section line A-A. 
         FIG. 2B  depicts another example force input sensor configured to detect force input to an electronic device, such as described herein. 
         FIG. 2C  depicts another example force input sensor configured to detect force input to an electronic device, such as described herein. 
         FIG. 2D  depicts another example force input sensor configured to detect force input to an electronic device, such as described herein. 
         FIG. 3A  depicts a force input sensor, such as described herein, including a linear arrangement of independent load cells. 
         FIG. 3B  depicts a rotated detail view of the enclosed circle B-B of  FIG. 3A , specifically depicting one load cell of the load cell array of  FIG. 3A . 
         FIG. 3C  depicts the load cell of  FIG. 3B , showing a diaphragm of the load cell deformed as a result of compression of the load cell. 
         FIG. 4A  depicts a load cell, such as described herein, that includes a diaphragm supported by a stiffener. 
         FIG. 4B  depicts a load cell, such as described herein, that includes a diaphragm supported by multiple stiffeners. 
         FIG. 4C  depicts another load cell, such as described herein, that includes a diaphragm supported by multiple stiffeners. 
         FIG. 5A  depicts an example stiffener that can support a diaphragm of a load cell, such as described herein. 
         FIG. 5B  depicts another example stiffener that can support a diaphragm of a load cell, such as described herein. 
         FIG. 5C  depicts another example stiffener that can support a diaphragm of a load cell, such as described herein. 
         FIG. 6A  depicts a load cell, such as described herein, that includes a strain sensor. 
         FIG. 6B  depicts a load cell, such as described herein, that includes multiple strain sensors. 
         FIG. 6C  depicts another load cell, such as described herein, that includes multiple strain sensors. 
         FIG. 7A  depicts a load cell, such as described herein, that includes a diaphragm supported by a resilient or flexible spacer. 
         FIG. 7B  depicts a load cell, such as described herein, that includes a diaphragm supported by another example resilient or flexible spacer. 
         FIG. 7C  depicts a load cell, such as described herein, that includes multiple strain sensors and a diaphragm supported by a resilient or flexible spacer. 
         FIG. 8A  depicts a load cell, such as described herein, including a loading feature coupled to a compression plate of the load cell. 
         FIG. 8B  depicts a load cell, such as described herein, including a loading feature that is formed from multiple layers of material coupled to a compression plate of the load cell. 
         FIG. 8C  depicts a load cell, such as described herein, including a loading feature and two support features that are each formed from multiple layers of material and coupled to compression plates of the load cell. 
         FIG. 9A  depicts another example load cell, such as described herein. 
         FIG. 9B  depicts the load cell of  FIG. 9A  including multiple strain sensors. 
         FIG. 10A  depicts a load cell, such as described herein, specifically showing one example routing of strain sensor electrodes. 
         FIG. 10B  depicts a load cell, such as described herein, specifically showing another example routing of strain sensor electrodes. 
         FIG. 10C  depicts a load cell, such as described herein, specifically showing yet another example routing of strain sensor electrodes. 
         FIG. 11  is a simplified flow chart showing example operations of a method of manufacturing a load cell, such as described herein. 
         FIG. 12  is a simplified flow chart showing example operations of another method of manufacturing a load cell, such as described herein. 
         FIG. 13  is a simplified flow chart showing example operations of another method of manufacturing a load cell, such as described herein. 
     
    
    
     The use of the same or similar reference numerals in different figures indicates similar, related, or identical items. 
     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 
     Embodiments described herein reference a force input sensor configured to couple to an internal edge or internal sidewall of an electronic device enclosure formed from one or more materials (and/or into a structure) that is resistant to local elastic deformation, such as, but not limited to: stainless steel, glass, sapphire, ceramics, structured metals or plastics, and/or carbon fiber. 
     More specifically, a force input sensor, such as described herein, defines and/or includes a compressible structure—referred to herein as a “load cell”—that includes two compression plates, separated from one another so as to define a volume between them. Typically, the compression plates are rectangular, and have a high aspect ratio (e.g., 5:1), although this may not be required. In many embodiments, a flexible spacer separates the two compression plates, but this may not be required. 
     A load cell, such as described herein, also includes a diaphragm positioned within, and extending across, the volume between the compression plates along a length of the compression plates. In typical implementations, one of the two compression plates includes a set or pair of supports defined at opposite ends of that compression plate. The supports extend, at least partly, into the volume defined between the compression plates. The supports also define attachment points for coupling opposite ends of the diaphragm to the compression plate, in order to suspend the diaphragm within the volume between the supports and between the two compression plates and, optionally, maintain tension in the diaphragm. The other compression plate of the load cell includes a loading feature coupled to—or formed integrally with—a central region of a length of that compression plate. In this manner, the loading feature extends into the volume in a direction opposite that of the supports. The loading feature extends toward—and, in many cases, contacts or otherwise abuts—a side of the diaphragm opposite the side of the diaphragm attached to the supports at the attachment points. In other words, when the load cell is assembled, the loading feature and the supports are on opposite sides of the diaphragm. 
     The load cell also includes a strain sensor disposed on the diaphragm, between the supports and below the loading feature. The strain sensor is electrically coupled to a measurement circuit configured to directly or indirectly measure an electrical property or effect of the strain sensor, such as, but not limited to: charge, inductance, resistance, capacitance, and so on. 
     As a result of this construction, the diaphragm, the loading feature, and the attachment points of the supports cooperate to define a three-point bending apparatus configured to adapt a compressive force applied to the compression plates into a strain experienced by the strain sensor on the diaphragm. More specifically, when a compressive force is applied to the compression plates, the flexible spacer compresses, reducing the distance between the compression plates. The reduced distance between the compression plates causes the loading feature and the supports to extend further into the volume, bending the diaphragm as a result. The bending moment induced in the diaphragm by the loading feature in turn induces a tension or compression in the strain sensor. In this manner, a relatively small change in the distance between the compression plates is adapted into a measurable strain in the strain sensor that can be electrically quantified by the measurement circuit (e.g., as a change in charge, resistance, capacitance, or inductance, and/or as a change in a signal applied to, or generated by, the strain sensor, such as a voltage signal, a current signal, a change in frequency, and so on). 
     In some embodiments, more than one support may not be required. In these examples, the diaphragm can be configured to cantilever, bending at a single point of inflection in response to a force applied by the loading feature. 
     As noted above, a load cell of a force input sensor, such as described herein, can be directly coupled to—and, in some cases, integrally formed with—an internal surface of a sidewall of an electronic device enclosure. More specifically, a compression plate of a load cell can be coupled to an internal surface of the sidewall. As a result of this construction, a force input applied by a user to an edge or a side of the electronic device enclosure compresses the load cell, which, as noted above, induces a strain in the strain sensor. Thereafter, the strain can be measured or inferred by the measurement circuit—using any suitable technique—and correlated to a magnitude of force corresponding to the force input provided by the user. In turn, a processor or circuit within the electronic device and communicably coupled to the measurement circuit can interpret the magnitude of force input from the measurement circuit as a user input to the electronic device. 
     In many embodiments, a force input sensor, such as described herein, is implemented with an array of independent load cells arranged in a pattern. For example, a force input sensor including an array of load cells arranged in a row can be disposed along a whole or partial length of an interior surface of a sidewall of an electronic device enclosure. As a result of this construction, a force input can be localized to a particular point or region of an external edge of the electronic device based on output obtained by the measurement circuit from one or more of the load cells of the force input sensor. In this example, the compression plates of adjacent load cells can be coupled together, but this may not be required. 
     In another example, a force input sensor includes four separate load cells arranged at corners of an electronic device housing. As a result of this construction, a force input can be localized to a particular corner or region of the exterior surface of the electronic device. 
     Accordingly, generally and broadly, it is understood that a force input sensor—such as described herein—can be used to detect one or more characteristics of one or more force inputs applied by a user of an electronic device to an edge or sidewall (or other surface) of an enclosure of the electronic device, substantially independent of the materials and/or constructions selected to manufacture the enclosure of the electronic device. Further, as a result of the constructions described herein, force inputs can be detected by a force input sensor of an electronic device substantially independent of a user&#39;s decision to protect the electronic device within a case that, as noted above, may be manufactured from a material and/or into a structure resistant to local elastic deformations and/or that may have the effect of diffusing local force inputs across a larger area. 
     For example, a force input sensor—such as described herein—may be configured to determine, without limitation: a location or region of the enclosure at which the force input is applied; a magnitude of the force input applied; a time derivative of the magnitude or the location of the force input applied; a force input gesture (e.g., a change in location and/or magnitude of a force input according to a pattern such as a swipe gesture, a press and release gesture, and so on); and so on. For simplicity of description, the embodiments that follow reference a force input sensor configured to quantify a magnitude of a force input applied by a user of an electronic device to an external edge or sidewall of an enclosure of that electronic device. It may be appreciated, however, that this is merely one category of example, and that additional or alternative characteristics of force input can be determined by a force input sensor—and/or a circuit coupled to a force input sensor—such as described herein. 
     As such, in view of the foregoing and following embodiments, it is understood that any suitable electronic device can include one or more force input sensors such as described herein, whether such force input sensors are coupled to an internal sidewall of an enclosure and/or to other components of the electronic device. Accordingly, for simplicity of description, the embodiments that follow reference a set of example constructions in which a force input sensor is coupled to—either directly or indirectly—an internal sidewall or internal edge of an enclosure of an electronic device. It is appreciated, however, that this is merely one example and that other configurations are possible in view of the embodiments described herein. 
     Additionally, it is understood that an electronic device including a force input sensor coupled to its enclosure can utilize the output(s) obtained from the measurement circuit of the force input sensor for any suitable purpose. For example, the electronic device may perform different functions in response to different detected force input characteristics, force input gestures, force input locations, and so on. Example functions that can be performed by the electronic device in response to a force input can include, but are not limited to: triggering launch, termination, or execution of a particular application or function of the electronic device (e.g., launching a virtual assistant, a calendar application, a voice memo application, a cellular phone application, and so on); increasing audio output volume in response to a force input (and/or gesture) provided to an upper portion of an edge of the enclosure; decreasing audio output volume in response to a force input (and/or gesture) provided to a lower portion of an edge of the enclosure; changing a power state of the electronic device (e.g., powered on, powered off, standby, and so on) in response to a force input to a top edge of the enclosure; modifying a graphical user interface in response to a force input (and/or gesture) applied to an edge of the enclosure; and so on. 
     These and other embodiments are discussed below with reference to  FIGS. 1-13 . 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 having an enclosure incorporating a force input sensor including a load cell array, such as described herein. In particular,  FIG. 1  depicts an electronic device  100  including an enclosure  102  (also referred to as a “housing”) and a touch-sensitive display  104  to generate a graphical user interface to encourage user interaction. 
     The enclosure  102  of the electronic device  100  can form an outer surface and protective case for the internal components of the electronic device  100 , including the notification system. In the illustrated embodiment, the enclosure  102  is formed in a substantially rectangular shape, although this is not required. The enclosure  102  can be formed of one or more components operably connected together, such as, but not limited to: a frame, a front cover, and a back cover; or a top clamshell and a bottom clamshell enclosed around an internal frame. Alternatively, the enclosure  102  can be formed of a single piece (e.g., a uniform body) of material. The enclosure  102  may be planar, or may be partially or entirely curved. 
     The touch-sensitive display  104  may include one or more touch sensors and/or force sensors that are configured to detect various combinations of user touch and force input on the exterior surface (e.g., the input surface  106 ) of the touch-sensitive display  104 . More specifically, the touch and/or force sensors may be used separately or in combination to interpret a broad range of user inputs such as, but not limited to: touch-based gestures; force-based gestures; touch patterns; tap patterns; single-finger gestures; multi-finger gestures; multi-force gestures; and so on. 
     The touch sensors and/or force sensors may be configured to interpret user input by comparing real-time touch and/or force input to one or more thresholds that may be static or variable, such as, but not limited to: downstroke force thresholds; upstroke force thresholds; movement thresholds; force magnitude thresholds; location thresholds; and so on. In addition, the touch and/or force sensors of the touch-sensitive display  104  may be configured to detect rates of change in touch input, force input, gesture input, or any combination thereof, that is provided by a user to the input surface. 
     The touch and/or force sensors associated with the touch-sensitive display  104  may be implemented in any number of suitable ways with any suitable technology or combination of technologies including, but not limited to: self-capacitance touch sensing; mutual capacitance touch sensing; resistive touch sensing; optical touch sensing; acoustic touch sensing; capacitive force sensing; strain-based force sensing; optical force sensing; acoustic force sensing; and so on, or any combination thereof. The touch and/or force sensors may be independently or mutually addressable and may be distributed and/or segmented and disposed relative to an active display region and/or a bezel region surrounding the touch-sensitive display  104 . 
     It may be appreciated that the touch-sensitive display  104  can be implemented with any suitable technology, including, but not limited to, a multi-touch or multi-force sensing touchscreen that uses liquid crystal display technology, light-emitting diode technology, organic light-emitting display technology, organic electroluminescence technology, or another type of display technology. 
     The electronic device  100  also includes a force input sensor  108 , separate from the touch-sensitive display  104 . In the illustrated example, the force input sensor  108  is disposed within the enclosure  102 , and positioned behind an opaque bezel  110  adjacent to, and surrounding, the touch-sensitive display  104 . In this manner, the force input sensor  108  is obscured from view by the opaque bezel  110 . 
     As noted with respect to other embodiments described herein, the force input sensor  108  is typically coupled to an internal sidewall of the enclosure  102 . As a result of this construction, the force input sensor  108  can receive force inputs provided to the sidewall of the enclosure  102 , such as the force input F 1  and the force input F 2  shown in  FIG. 1 . 
     In some examples, such as shown in  FIG. 1 , the force input sensor  108  can extend along a substantial portion of the sidewall of the enclosure  102 —such as depicted in  FIG. 1 —but this may not be required. For example, in other embodiments, the electronic device  100  can be configured to include, without limitation: more than one force input sensor arranged along a single sidewall of the enclosure  102 ; one or more force input sensors arranged along each sidewall of the enclosure  102 ; a single force input sensor extending around a periphery of the enclosure  102 ; a single force input sensor disposed on a bottom or a top sidewall of the enclosure  102 ; and so on. As such, generally and broadly, it may be appreciated that any suitable number of force input sensors—such as described herein—can be configured in any suitable manner and can be incorporated into any suitable electronic device enclosure or housing. 
     More specifically, it may be appreciated that the foregoing embodiments depicted in  FIG. 1  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various alternative configurations of a force input sensor and the various components thereof, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     For example, although the electronic device  100  is depicted as a cellular telephone, it may be appreciated that this is merely one example and that a force input sensor, such as described herein, may be incorporated into any suitable electronic device, system, or accessory including but not limited to: portable electronic devices (e.g., battery-powered, wirelessly-powered devices, tethered devices, and so on); stationary electronic devices; control devices (e.g., home automation devices, industrial automation devices, aeronautical or terrestrial vehicle control devices, and so on); personal computing devices (e.g., cellular devices, tablet devices, laptop devices, desktop devices, and so on); wearable devices (e.g., implanted devices, wrist-worn devices, eyeglass devices, goggle devices, augmented or virtual reality display or projector devices, and so on); accessory devices (e.g., protective covers such as keyboard covers for tablet computers, stylus input devices, charging devices, and so on); and so on. 
     Accordingly, for simplicity of description, the embodiments that follow reference an electronic device with a force input sensor coupled to a single internal sidewall of the device&#39;s enclosure; as noted above, it may be appreciated that this is merely one example. 
     A force input sensor, such as the force input sensor  108  and/or such as described in reference to other embodiments described herein, can be coupled, either directly or indirectly, to a sidewall of an electronic device enclosure in a number of suitable ways. Generally and broadly,  FIGS. 2A-2D  depict four example electronic device enclosure constructions including a force input sensor. 
     In particular,  FIG. 2A  depicts a cross-section of the electronic device  100 , taken through section line A-A of  FIG. 1 , specifically depicting the enclosure  102  now identified as the enclosure  200   a . In the illustrated example embodiment, the enclosure  200   a  includes a front cover  202   a , a back cover  202   b , and a frame  204 . The front cover  202   a  and the back cover  202   b  can be adhered to and/or sealed to the frame  204  via an adhesive or sealant, identified as the gasket  206 . The force input sensor  108  of  FIG. 1  is identified in  FIG. 2A  as the force input sensor  208 . In this embodiment, the force input sensor  208  is positioned between the frame  204  and a support  210  that is coupled to at least one of the front cover  202   a  or the back cover  202   b . In the illustrated example, the support  210  extends from the back cover  202   b , but this is merely one example configuration. 
     As a result of the illustrated example construction, a force input F applied to (and at an angle relative to) an exterior surface of the frame  204  causes the force input sensor  208  to compress. More specifically, the force input F applied to the exterior surface of the frame  204  causes the frame  204  to locally deform, shearing the gasket  206  in a direction parallel to the force input F such that the frame  204  advances toward the support  210  to a degree dependent on the construction and/or materials selected for the enclosure  200   a . As a result, the force input sensor  208 —or, more particularly, a load cell (not shown) within the force input sensor  208 —compresses to a degree dependent on the enclosure  200   a  and the force input sensor  208 . As noted with respect to other embodiments described herein, the compression of the force input sensor  208  can be measured, either directly or indirectly, by a measurement circuit (not shown). Thereafter, the output of the measurement circuit can be correlated to a magnitude of the force input F. 
     In the illustrated example, the force input F is depicted as being applied normal to an external surface of the frame  204  (e.g., perpendicular to the frame  204 ), but this is not required; it may be appreciated that a force input F may be applied at a number of suitable angles—each of which may include at least one component normal to the surface of the frame  204 —relative to the frame  204  and/or to the force input sensor  208 . 
     Furthermore, the example construction shown in  FIG. 2A  is merely one example; other embodiments can be implemented in different ways. 
     For example,  FIG. 2B  depicts another example construction in which a force input sensor is configured to detect force input applied to an exterior sidewall of an electronic device. As with the embodiment of  FIG. 2A , the enclosure  200   b  includes a front cover  202   a , a back cover  202   b , and a frame  204  coupled via a gasket  206 . In this embodiment, the force input sensor  208  is positioned between the frame  204  and an internal component  212  of the electronic device enclosed within the enclosure  200   b . The internal component  212  can be any suitable internal component of an electronic device including, but not limited to: an internal frame or support; a haptic actuator; a camera; a display stack; a battery; a wireless charging coil; a button or input component; a main or daughter logic board; a sensor; an electromagnetic shield; an antenna; and so on. 
     As a result of the illustrated example construction, similar to the embodiment described above in reference to  FIG. 2A , a force input F applied to (and at an angle relative to) an exterior surface of the frame  204  causes the force input sensor  208  to compress. More specifically, the force input F applied to the exterior surface of the frame  204  causes the frame  204  to locally deform, shearing the gasket  206  in a direction parallel to the force input F such that the frame  204  advances toward the internal component  212  to a degree dependent on the construction and/or materials selected for the enclosure  200   b . As a result, the force input sensor  208  compresses. The compression of the force input sensor  208  can be measured, either directly or indirectly, by a measurement circuit and, thereafter, the output of the measurement circuit can be correlated to a magnitude of the force input F. 
     As with the embodiment described above in reference to  FIG. 2A , in the illustrated example, the force input F is depicted as being applied normal to an external surface of the frame  204  (e.g., perpendicular to the frame  204 ), but this is not required; it may be appreciated that a force input F may be applied at a number of suitable angles—each of which may include at least one component normal to the surface of the frame  204 —relative to the frame  204  and/or to the force input sensor  208 . 
       FIG. 2C  depicts yet another example construction in which a force input sensor is configured to detect force input applied to an exterior sidewall or edge of an electronic device. As with the embodiments of  FIGS. 2A-2B , the enclosure  200   c  includes a front cover  202   a , a back cover  202   b , and a frame  204  coupled via a gasket  206 . In this embodiment, the force input sensor  208  is positioned on a shelf  214  extending from the frame  204  at an angle. 
     In the illustrated embodiment, the shelf  214  extends perpendicular to an internal surface of the frame  204 , but this may not be required; other implementations may find other angles relative to the frame  204  (or relative to another component of the enclosure  200   c  or the electronic device enclosed by the enclosure  200   c ) to be preferred and/or otherwise suitable. 
     In the illustrated embodiment, the force input sensor  208  is also coupled to an internal surface of the front cover  202   a . In other words, the force input sensor  208  is disposed in an upper corner of the enclosure  200   c , coupling an upper region of the internal surface of the frame  204  to an interior surface of the front cover  202   a . It may be appreciated, additionally, that in other examples, the force input sensor  208  can be disposed in a lower corner of the enclosure  200   c , coupling a lower region of the internal surface of the frame  204  to the back cover  202   b.    
     As a result of the illustrated example construction, a force input F applied to (and at an angle relative to) an exterior surface of the frame  204  causes the force input sensor  208  to compress and/or shear relative to the front cover  202   a . More specifically, the force input F applied to the exterior surface of the frame  204  causes the frame  204  to locally deform, shearing and/or compressing the gasket  206  such that the frame  204  and/or the front cover  202   a  advances, to some degree, inwardly relative to the enclosure  200   c . As a result, the force input sensor  208  shears and/or compresses between the shelf  214  and the front cover  202   a . The compression and/or shearing of the force input sensor  208  can be measured, either directly or indirectly, by a measurement circuit and, thereafter, the output of the measurement circuit can be correlated to a magnitude of the force input F. 
     In the illustrated example, the force input F is depicted as being applied at an angle approximately forty-five degrees offset from an external surface of the frame  204 , but this is not required; it may be appreciated that a force input F may be applied at a number of suitable angles—some and/or each of which may include at least one component normal to the surface of the frame  204  and/or at least one component normal to an external surface of the front cover  202   a —relative to the frame  204 , the front cover  202   a , and/or to the force input sensor  208 . 
       FIG. 2D  depicts yet another example construction in which a force input sensor is configured to detect force input applied to an exterior sidewall or edge of an electronic device. As with the embodiments of  FIGS. 2A-2C , the enclosure  200   d  includes a front cover  202   a , a back cover  202   b , and a frame  204  coupled via a gasket  206 . In this embodiment, the force input sensor  208  is positioned between the front cover  202   a  and an internal component  212  of the electronic device enclosed within the enclosure  200   d . As with the embodiment described in reference to  FIG. 2B , the internal component  212  can be any suitable internal component of an electronic device including, but not limited to: an internal frame or support; a haptic actuator; a camera; a display stack; a battery; a wireless charging coil; a button or input component; a main or daughter logic board; a sensor; an electromagnetic shield; an antenna; and so on. 
     As a result of the illustrated example construction, a force input F applied to (and at an angle relative to) an exterior surface of the frame  204  causes the force input sensor  208  to compress and/or shear relative to the front cover  202   a . More specifically, the force input F applied to the exterior surface of the frame  204  causes the frame  204  and/or the front cover  202   a  to locally deform, shearing and/or compressing the gasket  206  such that front cover advances inwardly relative to the enclosure  200   d . As a result, the force input sensor  208  shears and/or compresses between the shelf  214  and the front cover  202   a . The compression and/or shearing of the force input sensor  208  can be measured, either directly or indirectly, by a measurement circuit and, thereafter, the output of the measurement circuit can be correlated to a magnitude of the force input F. 
     In the illustrated example, as with the embodiment described above in reference to  FIG. 2C , the force input F is depicted as being applied at an angle approximately forty-five degrees offset from to an external surface of the frame  204 . It may be appreciated that this particular angle is neither required nor preferred; a force input F may be applied at a number of suitable angles—some and/or each of which may include at least one component normal to the surface of the frame  204  and/or at least one component normal to an external surface of the front cover  202   a —relative to the frame  204 , the front cover  202   a , and/or to the force input sensor  208 . 
     The foregoing embodiments depicted in  FIGS. 2A-2D  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various configurations and constructions of a force input sensor within an electronic device enclosure, and the various components thereof, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a force input sensor coupled to an internal surface of an electronic device enclosure are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, although several discrete examples are provided above, it may be appreciated that a force input sensor, such as described herein, can be coupled to an electronic device enclosure in a number of suitable ways. Additional example constructions include: a force input sensor coupled between a first angled shelf (e.g., forty-five degrees) extending from a sidewall of an enclosure and a second angled shelf (e.g., forty-five degrees) extending from a cover of the enclosure such that the force input sensor is oriented at an angle relative to a corner of the enclosure; a first force input sensor coupled relative to an upper cover of an enclosure at which a front cover and a frame of the enclosure meet and a second force input sensor coupled relative to a lower cover of the enclosure at which a back cover and the frame of the enclosure meet; a force input sensor disposed below a display surface of an electronic device enclosure; a force input sensor relative to an interior surface of an electronic device housing opposite a texture, embossment, debossment, or other tactile feature defined on an exterior surface of the enclosure opposite the interior surface and the force input sensor; and so on. 
     Generally and broadly,  FIGS. 3A-3C  depict a cross-section of an example force input sensor—identified as the force input sensor  300 —such as described herein. As shown in  FIG. 3A , the force input sensor  300  includes an array of load cells, one of which is identified as the load cell  302 , shown in detail view in  FIGS. 3B-3C . In the illustrated embodiment, eight discrete load cells are depicted, but this is merely one example and other force input sensor embodiments can include a greater or fewer number of load cells. 
     In the illustrated example, the force input sensor  300  and, likewise, the load cell  302 , are coupled to a surface  304 . The surface  304 —as noted with respect to other embodiments described herein—can be any suitable internal surface (formed from any suitable material, including glass, plastic, metal, ceramic, and so on) of an electronic device enclosure or a component of an electronic device enclosure. In typical examples, the surface  304  is an internal surface of a sidewall of an electronic device enclosure that is resistant to local elastic deformation, such as the enclosure  102  depicted in  FIG. 1 . 
     The force input sensor  300  can be coupled to the surface  304  using any suitable fastening, attachment, bonding, or coupling technique. For example, the force input sensor  300  can be coupled to the surface by, without limitation: adhesive; interference fit; welding; co-molding; mechanical fasteners; and so on, or any combination thereof. 
     In the illustrated embodiment, each load cell of the force input sensor  300 —including the load cell  302 —includes two compression plates, separated from one another so as to define a volume between them. More specifically, a first compression plate is identified as the compression plate  306   a  and a second compression plate is identified as the compression plate  306   b . The volume defined between the compression plate  306   a  and the compression plate  306   b  is identified as the volume  306   c . Each load cell also includes a diaphragm  308  positioned within, and extending across, the volume  306   c  between the compression plates  306   a ,  306   b  along a length of the compression plates  306   a ,  306   b.    
     In the illustrated example, the compression plates  306   a ,  306   b  contiguously extend across the entire length of the force input sensor  300 . In other words, each of the load cells of the force input sensor  300  share the compression plates  306   a ,  306   b . It may be appreciated, however, that this is merely one example configuration and may not be required of all embodiments. For example, in further cases, adjacent load cells of a force input sensor—such as described herein—can be separated and/or singulated. 
     In the illustrated example, the compression plates  306   a ,  306   b  are rectangular and have a high aspect ratio (e.g., greater than 2:1, greater than 5:1, greater than 10:1, and so on). More specifically, the width of the compression plates  306   a ,  306   b  is smaller than the length of the compression plates  306   a ,  306   b . In one specific, non-limiting, example, the load cell  302  is approximately 2 mm in width (a dimension not shown in the two-dimensional cross sections of  FIGS. 3A-3C ; the width is understood to extend out of or into the page) and 10-15 mm in length. In another example, the load cell  302  is less than 1 mm in width and 20 mm in length. In view of these discrete examples, it may be appreciated that the aspect ratio and general shape of the compression plates  306   a ,  306   b  may vary from embodiment to embodiment. Example suitable shapes for the compression plates  306   a ,  306   b  include, without limitation: rounded shapes; hexagonal shapes; triangular shapes; and so on. 
     In typical embodiments, the compression plates  306   a ,  306   b  are formed from the same material, but this may not be required. Example suitable materials for the compression plates  306   a ,  306   b  include, but are not limited to: metals; plastics; glass; synthetic materials; acrylics; and so on. 
     In many examples, the compression plates  306   a ,  306   b  are formed into a shape or structure, or from a material or combination of materials, that is generally resistant to local deformation. In other words, in these embodiments, the compression plates  306   a ,  306   b  are formed such that a compressive force applied to the load cell  302  results in a reduction of the volume  306   c  and not a substantive deformation of either or both the compression plates  306   a ,  306   b.    
     The diaphragm  308  extending between the compression plates  306   a ,  306   b  is typically formed from a flexible material, such as a plastic or flexible circuit board material. The diaphragm  308  can be supported by stiffeners (not shown), but this may not be required. The diaphragm  308  may be made from a single layer of material or multiple layers of material. 
     For simplicity of description, many embodiments that follow reference a single load cell—for example, the load cell  302  as shown in the detail view of  FIGS. 3B and 3C . It may be appreciated, however, that other load cells of a single force input sensor may be similarly configured. 
     As noted above, the diaphragm  308  of the load cell  302  is positioned within, and extends across, the volume  306   c  between the compression plates  306   a ,  306   b.    
     The compression plate  306   a  includes two supports, identified as the supports  310   a ,  310   b . The supports  310   a ,  310   b  extend, at least partially, into the volume  306   c  defined between the compression plates  306   a ,  306   b  of the load cell  302 . The supports  310   a ,  310   b  also define attachment points—identified as the attachment points  312   a ,  312   b —for coupling to opposite ends of the diaphragm  308 . In this manner, the diaphragm  308  is at least partially suspended within the volume  306   c  between the supports  310   a ,  310   b  and between the compression plates  306   a ,  306   b . In some cases, the attachment points  312   a ,  312   b  maintain a select tension in the diaphragm  308 , but this may not be required. 
     In the illustrated example, the supports  310   a ,  310   b  are formed integrally with the compression plate  306   a . The supports  310   a ,  310   b  can be manufactured and/or formed onto the compression plate  306   a  using any suitable technique including, but not limited to: machining; etching; stamping; ablating; sputtering; deposition; additive manufacturing; and so on. 
     The compression plate  306   b  of the load cell  302  includes a loading feature  314  extending from a central region of a length of the compression plate  306   b . In some implementations, the loading feature  314  may be referred to as a loading nose, a bending fulcrum, a force applicator, a strain concentrator, a force concentrator, a force concentrating feature, a protrusion, or a strain concentrating feature. The loading feature  314  extends into the volume  306   c  in a direction opposite that of the supports  310   a ,  310   b . In this example, the loading feature  314  extends toward, and interfaces with, the diaphragm  308 . 
     As with the supports  310   a ,  310   b , in the illustrated example, the loading feature  314  is formed integrally with the compression plate  306   b , but this may not be required. In typical examples, such as shown, the loading feature  314  has an inverted curve profile, such as an inverted Gaussian curve or inverted normal curve. In other cases, a curved profile may not be required. Other suitable profile shapes for a loading feature, such as described herein (e.g., the loading feature  314 ) include, but are not limited to: a triangular profile; a circular profile; a multi-face profile; and so on. 
     Also as with the supports  310   a ,  310   b , the loading feature  314  can be manufactured and/or formed onto the compression plate  306   b  using any suitable technique including, but not limited to: machining; etching; stamping; ablating; sputtering; deposition; additive manufacturing; and so on. 
     The load cell  302  also includes a strain sensor  316  disposed on the diaphragm  308 , between the supports  310   a ,  310   b  and below the loading feature  314 . The strain sensor  316  is electrically coupled to a measurement circuit (not shown) configured to directly or indirectly measure a change in an electrical property or effect of the strain sensor  316 , such as, but not limited to changes in: charge, inductance, resistance, capacitance, and so on. 
     In many embodiments, the strain sensor  316  is defined by an electrical trace formed from a piezoresitive material that follows a serpentine pattern disposed on an outer surface of the diaphragm  308 . However, it may be appreciated that this configuration is merely one example; additional or alternative strain sensor types, electrical trace patterns, and strain sensor distribution patterns may be suitable. 
     Example suitable strain sensor types that may be suitable in certain implementations include, without limitation: piezoelectric strain sensors; capacitive strain sensors; inductive strain sensors; and so on. 
     Examples suitable electrical trace patterns include, but are not limited to: vertically-aligned serpentine patterns (e.g., disposed on opposite surfaces of the diaphragm  308 ); horizontally-aligned serpentine patterns (e.g., disposed on the same surface of the diaphragm  308 ); angled serpentine patterns; spiral patterns; double-back spiral patterns; interdigitated serpentine patterns; comb patterns; rectilinear patterns; curved patterns; polygonal patterns; and so on, or any combination thereof. 
     Example embodiments including more than one strain sensor on the diaphragm  308  can include, but may not be limited to: multiple discrete and individually-addressable strain sensors disposed in regular patterns, irregular patterns, tessellated patterns, repeating patterns, multi-layer patterns, single-layer patterns, and so on; a strain sensing network including multiple discrete strain sensors electrically coupled in a balancing network, such as a Wheatstone bridge or a voltage divider; an auxiliary strain sensor disposed onto a surface of one or both of the compression plates  306   a ,  306   b ; an auxiliary strain sensor disposed onto a surface of the loading feature  314 ; an auxiliary strain sensor disposed onto a surface of the supports  310   a ,  310   b ; an auxiliary strain sensor formed within and/or encapsulated by the diaphragm  308 ; and so on, or any combination thereof. 
     As a result of the illustrated construction of the load cell  302  (see, e.g.,  FIG. 3B ), the diaphragm  308 , the loading feature  314 , and the attachment points  312   a ,  312   b  of the supports  310   a ,  310   b  cooperate to define a three-point bending apparatus configured to adapt a compressive force applied to the compression plates  306   a ,  306   b  into a strain experienced by the strain sensor  316  on the diaphragm  308 . 
     More specifically, when a compressive force F is applied to the compression plates (see, e.g.,  FIG. 3C ), the volume  306   c  compresses, reducing the distance between the compression plates  306   a ,  306   b . The reduced distance between the compression plates  306   a ,  306   b  causes the loading feature  314  (and, additionally or alternatively, the supports  310   a ,  310   b ) to extend further into the volume  306   c , bending the diaphragm  308  as a result. 
     The bending moment induced in the diaphragm  308  by the loading feature  314  in turn induces a tension or compression in the strain sensor  316  that can be measured by the measurement circuit. In this manner, a relatively small change in the distance between the compression plates  306   a ,  306   b  is adapted into a measurable strain in the strain sensor  316  that can be quantified by the measurement circuit (e.g., as a change in charge, resistance, capacitance, or inductance, and/or as a change in a signal applied to, or generated by, the strain sensor  316 , such as a voltage signal, a current signal, a change in frequency, and so on). 
     More specifically, in operation, the measurement circuit (which can be an analog or digital circuit, processor, or combination thereof) can be configured to apply an electrical signal (a “stimulus signal” or a “drive signal”) to an input lead of the strain sensor  316 . After applying the stimulus signal to the strain sensor  316 , the measurement circuit can receive or obtain a sense signal from an output lead of the strain sensor  316 . 
     Thereafter, the measurement circuit (or another processor or circuit) can analyze or otherwise process the sense signal to quantify an electrical property of the strain sensor  316  (e.g., inductance, reactance, resistance, capacitance, and so on) that corresponds to one or more physical dimensions of that sensor, such as, but not limited to: length; width; or area. 
     For example, as noted above, in many cases the strain sensor  316  is formed from peizoresistive material that exhibits a change in resistance proportional to a change in length. In other cases, the strain sensor  316  can exhibit a change in inductance as a function of the length or area. In still other cases, the strain sensor  316  can exhibit a change in reactance as a function of the length or area. After determining and/or quantifying the electrical property of the trace, the measurement circuit of the force input sensor  300  can correlate that measurement or quantity to a magnitude of strain experienced by the strain sensor  316 . Thereafter, the force input sensor  300 —or an electronic device incorporating the same—can correlate the strain experienced by the strain sensor  316  to a magnitude of force input applied. 
     The foregoing embodiments depicted in  FIGS. 3A-3C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various configurations and constructions of a force input sensor, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a force input sensor are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, as noted above, in some examples, a diaphragm of a load cell of a force input sensor, such as described herein, can be supported by a stiffener. A stiffener can serve to concentrate strain in a specific region of the diaphragm by limiting the regions of the diaphragm that flex in response to the bending moment(s) induced by the loading feature of the load cell.  FIGS. 4A-4C  depict example configurations of a load cell that include one or more stiffeners. 
     For example,  FIG. 4A  depicts a load cell  400   a . As with other embodiments described herein, the load cell  400   a  is configured to couple to a surface  402  of an electronic device enclosure. The load cell includes a compressible structure  404  that includes a first compression plate  404   a  and a second compression plate  404   b  separated by a gap that defines a volume between the two compression plates. As with other embodiments described herein, a diaphragm  406  is positioned within the gap/volume defined between the compression plates of the compressible structure  404 . The load cell  400   a  also includes a strain sensor  408  disposed on the diaphragm  406 . In particular, the strain sensor  408  is disposed on a side of the diaphragm  406  that is facing a loading feature extending from the first compression plate  404   a . The load cell  400   a  also includes a stiffener  410  positioned on a side of the diaphragm  406  opposite the strain sensor  408 . As a result of this construction, the stiffener  410  mechanically strengthens the diaphragm  406  to concentrate strain in the strain sensor  408 . 
     In other examples, a stiffener can be positioned in other locations or may take other forms. For example,  FIG. 4B  depicts a load cell  400   b  coupled to a surface  402  of an electronic device enclosure. Like the embodiment depicted in  FIG. 4A , the load cell  400   b  includes a compressible structure  404 , a diaphragm  406 , and a strain sensor  408  disposed on the diaphragm  406 . In this example, like the example depicted in  FIG. 4A , a stiffener  410  is disposed on a bottom surface of the diaphragm  406 , opposite the strain sensor  408 . However, different from  FIG. 4A , the stiffener  410  depicted in  FIG. 4B  includes a cutout  412  positioned immediately below the strain sensor  408 . In this manner, the stiffener  410  is effectively bifurcated into two sections—a first stiffener section  410   a  and a second stiffener section  410   b . As a result of the cutout  412 , the diaphragm  406  is biased to bend (e.g., to strain) in response to a compressive force applied to the load cell  400   b  in the region defined by the cutout  412 , thereby concentrating strain in the diaphragm  406  in a region of the diaphragm  406  associated with the strain sensor  408 . 
     In still other examples, a load cell can include stiffeners on multiple surfaces of a diaphragm. For example,  FIG. 4C  depicts another load cell  400   c  coupled to a surface  402  of an electronic device enclosure. Like the embodiments depicted in  FIGS. 4A-4B , the load cell  400   c  includes a compressible structure  404 , a diaphragm  406 , and a strain sensor  408  disposed on the diaphragm  406 . In this example, like the example depicted in  FIG. 4B , a stiffener  410  (identified as the stiffener sections  410   a ,  410   b ) include a cutout  412  that is disposed on a bottom surface of the diaphragm  406 , opposite the strain sensor  408 . In this example, a second stiffener is disposed on a top surface of the diaphragm  406 . As with the stiffener  410 , the stiffener is bifurcated into two sections, identified in the figure as the stiffener section  412   a  and the stiffener section  412   b.    
     The foregoing embodiments depicted in  FIGS. 4A-4C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various configurations and constructions of a stiffener that can support a diaphragm of a load cell, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a stiffener of a load cell are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, it may be appreciated that a stiffener can be formed from any number of suitable materials including, but not limited to: metals; plastics; structured plastics; ceramics; glass; and so on. Similarly, it may be appreciated that a stiffener, such as described herein, can be adhered to or otherwise adhered to a diaphragm in any suitable manner, including but not limited to: adhesive; fasteners; machining; etching; stamping; ablating; sputtering; deposition; additive manufacturing; and so on. 
     Further, it may be appreciated that one or more stiffeners can be disposed in any suitable pattern on any suitable surface of a diaphragm of a load cell, such as described herein. 
     In still further examples, it may be appreciated that a stiffener can include one or more cutouts, indents, or other structure that guides or otherwise concentrates strain in the diaphragm in a particular region. For example, generally and broadly,  FIGS. 5A-5C  depict example stiffeners that can be coupled to a diaphragm of a load cell, such as described herein. Each of the stiffeners depicted in  FIGS. 5A-5C  include a different cutout shape that may be suitable in certain embodiments to concentrate strain onto a strain sensor disposed onto the diaphragm to which the depicted stiffener is configured to attach. 
     For example,  FIG. 5A  depicts an example stiffener that can support a diaphragm of a load cell, such as described herein. In particular, the stiffener—identified as the stiffener  500   a —includes a body  502 . A cutout  504  is defined entirely or partially through a central region of the body  502 . As a result of this construction, the cutout  504  introduces a bias into the body  502  of the stiffener  500   a  such that when a bending moment is induced into the stiffener  500   a  (e.g., via a loading feature of a compression plate of a load cell, such as described herein, applying a downward force to a diaphragm to which the stiffener  500   a  is coupled), the body  502  bends to a greater extent in the region of the body  502  adjacent to the cutout  504 . As a result of this construction, a load cell such as described herein incorporating the depicted stiffener can position a strain sensor adjacent to—and/or otherwise aligned with—the cutout  504  of the stiffener in order to effect a concentration of strain in the strain sensor, thereby mechanically amplifying the strain experienced by the strain sensor. In this example, the cutout  504  takes the shape of a rounded rectangle, having a length oriented perpendicular to a length of the body  502 . This, however, is merely one example and a cutout such as depicted can be angled and/or positioned in any suitable manner. In other cases, the body  502  can include multiple parallel and/or intersecting cutouts configured in a manner intended to mechanically amplify strain in a particular region of a diaphragm to which the stiffener  500   a  is coupled. 
     For example, such as shown in  FIG. 5B , a stiffener  500   b  can include a body  502  through which a cross-shaped cutout, identified as the cutout  504 , is defined. As depicted, arms of the cross shape of the cutout  504  are generally aligned with perpendicular and parallel axes relative to a length of the body  502 , but this may not be required; in other examples, a cross-shaped cutout can be rotated and/or oriented in another manner. 
     In yet another example, such as shown in  FIG. 5C , a stiffener  500   c  can include a body  502  through which a circular cutout, identified as the cutout  504 , is defined. 
     The foregoing embodiments depicted in  FIGS. 5A-5C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various configurations and constructions of a stiffener including a cutout that can support a diaphragm of a load cell, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a cutout of a stiffener of a load cell are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, it may be appreciated that the specific examples provided in reference to  FIGS. 5A-5C  are merely examples and that other cutout constructions can be included in other embodiments. For example, without limitation: a cutout of some embodiments may be defined only partially through a body of a stiffener; a cutout of some embodiments can take a shape of, without limitation, a square, a rectangle, an octagon, a triangle, a bowtie shape, an interdigitated shape, a comb shape, and so on; some embodiments include an array of cutouts arranged in a pattern; some embodiments include an array and/or distribution of discrete regions arranged in a pattern, grid, or other manner; and so on. 
     In still other examples, a stiffener may not be required. For example,  FIGS. 6A-6C  generally and broadly depict embodiments of a load cell, such as described herein, that may not require a stiffener. 
     For example,  FIG. 6A  depicts a load cell, such as described herein, that includes a strain sensor disposed on a surface of a diaphragm positioned opposite a loading feature extending from a compression plate that interfaces the diaphragm. In particular, the figure depicts a load cell  600   a  coupled to a surface  602  of an electronic device enclosure. As with other embodiments described herein, the surface  602  is typically an internal surface of a sidewall of an electronic device enclosure, but this may not be required. 
     As noted above, the load cell  600   a  includes a compressible structure  604  that includes a first compression plate  604   a  and a second compression plate  604   b , separated by a gap and defining a volume. In some cases, the gap can be maintained by a flexible spacer positioned between the first compression plate  604   a  and the second compression plate  604   b , but this may not be required of all embodiments. In some cases, the flexible spacer can be made from silicon, plastic, elastic, and/or another material. In still further examples a flexible spacer can be made from a metal or plastic, and formed in the shape of a spring, such as a coil spring or leaf spring. In view of the various examples provided above it may be appreciated that, generally and broadly, a flexible space can be implemented—if required—in any number of suitable ways. 
     As with other embodiments described herein, the load cell  600   a  also includes a diaphragm  606  that is disposed within the volume defined between the first compression plate  604   a  and the second compression plate  604   b . More specifically, as with other embodiments described herein, the diaphragm  606  is supported by and between two supports extending from the second compression plate  604   b.    
     The diaphragm  606  also includes a strain sensor  608  that is disposed on a surface of the diaphragm  606  opposite a loading feature that extends from the first compression plate  604   a  toward, and contacts, abuts, or interfaces, the diaphragm  606 . 
     As a result of this construction, when a compressive force is applied to the load cell  600   a , the volume between the compression plates of the compressible structure  604  decreases, thereby causing the loading feature of the first compression plate  604   a  to induce a bending moment into the diaphragm  606 , causing the strain sensor  608  to experience strain. As with other embodiments described herein, the tension or compression experienced by the strain sensor  608  can be measured by a measurement circuit and, thereafter, correlated to an amount of force input applied. 
       FIG. 6B  depicts another example load cell, such as described herein. The load cell  600   b , like the load cell  600   a  depicted in  FIG. 6A , is coupled to a surface  602  of an electronic device enclosure. 
     The load cell  600   b  includes a compressible structure  604  that includes a first compression plate and a second compression plate separated by a gap and defining a volume across which and through which a diaphragm  606  is disposed. In this embodiment the diaphragm  606  includes multiple strain sensors, each of which is identified as a strain sensor  608 , and each of which is disposed on a surface and/or region of the diaphragm  606  likely to experience strain in response to an induced bending moment in the diaphragm  606 . 
     In particular, in the illustrated embodiment, the load cell  600   b  includes a first strain sensor  608   a  disposed on the diaphragm  606  below a first inflection point at which the diaphragm  606  interfaces a loading feature extending from a first compression plate of the compressible structure  604 . 
     In addition, the load cell  600   b  includes a second strain sensor  608   b  disposed on the diaphragm  606  relative to a second inflection point at which the diaphragm  606  is coupled to a first support extending from a second compression plate of the compressible structure  604 . Similarly, the load cell  600   b  includes a third strain sensor  608   c  disposed on the diaphragm  606  relative to a third inflection point at which the diaphragm  606  is coupled to a second support extending from a second compression plate of the compressible structure  604 . 
     As a result of this construction, when a compressive force is applied to the load cell  600   b , the volume between the compression plates of the compressible structure  604  decreases, thereby causing the loading feature of the first compression plate to induce a bending moment into the diaphragm  606 , causing the strain sensors  608   a ,  608   b , and  608   c  to experience strain. As with other embodiments described herein, the tension or compression experienced by the strain sensors  608   a ,  608   b , and  608   c  can be measured by a measurement circuit and, thereafter, correlated to an amount of force input applied. 
       FIG. 6C  depicts yet another example load cell, such as described herein. The load cell  600   c , like the load cells depicted in  FIGS. 6A-6B , is coupled to a surface  602  of an electronic device enclosure. 
     As with preceding embodiments, the load cell  600   c  includes a compressible structure  604  that includes a first compression plate and a second compression plate separated by a gap and defining a volume across which and through which a diaphragm  606  is disposed. Similar to the embodiment of  FIG. 6B , in this embodiment, the diaphragm  606  includes multiple strain sensors, each of which is identified as a strain sensor  608 , and each of which is disposed on a surface and/or region of the diaphragm  606  likely to experience strain in response to an induced bending moment in the diaphragm  606 . 
     In this embodiment, however, the loading feature extending from the first compression plate is adhered to the diaphragm  606  via an adhesive  610 . As a result of the adhesive  610 , the diaphragm  606  may be locally strengthened in the region adjacent to the loading feature. 
     As a result of this construction, the diaphragm  606 , the adhesive  610 , the loading feature, and the attachment points of the supports cooperate to define a four-point bending apparatus configured to adapt a compressive force applied to the compressible structure  604  into a strain experienced by the strain sensors  608  disposed on the diaphragm  606 . More specifically, when a compressive force is applied to the compression plates, the distance between the compression plates reduces. The reduced distance between the compression plates causes the loading feature to extend further into the volume, bending the diaphragm  606  as a result. However, as a result of the mechanical support afforded to the central region of the diaphragm  606  by the adhesive  610 , the diaphragm  606  may experience greater strain in regions adjacent to the central region than in the central region itself. Accordingly, as illustrated, the strain sensors  608  (specifically identified as the strain sensor  608   e  and the strain sensor  6080  are positioned adjacent to the central region of the diaphragm  606 . 
     The foregoing embodiments depicted in  FIGS. 6A-6C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various distributions of a strain sensor—or more than one strain sensor—on a diaphragm of a load cell, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of one or more strain sensors despised on a diaphragm of a load cell are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, other load cells can include, without limitation: strain sensors disposed in a two-dimensional array, grid, or matrix; strain sensors of different types (e.g., capacitive, inductive, and so on) disposed relative to different regions of a diaphragm; strain sensors of different constructions disposed relative to different regions of a diaphragm; strain sensors disposed on different sides of a diaphragm; strain sensors disposed on opposite sides of a diaphragm and electrically coupled to one another in a balancing network, such as a Wheatstone bridge; strain sensors disposed within a thickness of a diaphragm; and so on. 
     Still further load cells can include additional features or components to concentrate strain and/or support one or both compression plates of a compressible structure, such as described herein. For example, generally and broadly,  FIGS. 7A-7C  depict example load cells that can be supported by flexible spacers formed from any number of suitable materials and/or into any number of suitable structures including, but not limited to: foam; silicone; flexible/corrugated structured plastic; and so on. 
     In particular,  FIG. 7A  depicts a load cell  700   a  that, like other embodiments described herein, is coupled to a surface  702 . The load cell  700   a  includes a compressible structure  704  that, in turn, includes a first compression plate  704   a  and a second compression plate  704   b . The compression plates of the compressible structure  704  are separated from one another by a gap so as to define a volume across which a diaphragm  706 , including a strain sensor  708 , extends. 
     This embodiment further includes a set of flexible spacers (also referred to herein as “cushioning supports”), identified as the spacers  710 , that flexibly couple the first compression plate  704   a  to the second compression plate  704   b . In some cases, the flexible spacers  710  can be formed from a foam or a silicone. In many embodiments, the flexible spacers  710  are adhered to each of the compression plates via an adhesive such as a pressure-sensitive or heat-sensitive adhesive. 
     In many examples, the flexible spacers  710  can increase the efficiency with which the load cell  700   a  is manufactured and/or assembled. In particular, the flexible spacers  710  can bond and/or otherwise couple and align the first compression plate  704   a  to the second compression plate  704   b . As a result, the load cell  700   a  can be manufactured in a roll-to-roll process. 
     In another example, such as depicted in  FIG. 7B , a cushioning support can be disposed below a diaphragm of a load cell such as described herein. In particular,  FIG. 7B  depicts a load cell  700   b  that is coupled to a surface  702  and includes a compressible structure  704  that defines a volume. A diaphragm  706  comprising a strain sensor  708  is disposed within the volume. In this example, a cushioning support  712  can be positioned below the diaphragm  706 . The cushioning support  712  can be formed from silicon, foam, or any other suitable compressible material. In some examples, the cushioning support  712  can include a liquid. 
     In some cases, a cushioning support may cause the diaphragm  706  to deform according to a specific profile. For example, in some embodiments, a cushioning support may be made from a material such as silicone that is generally incompressible. As a result, the cushioning support tends to bulge at its edges in response to receiving a downward force in its center. As may be appreciated, the bulging of the cushioning support can cause the diaphragm to bulge as well. In these cases, such as shown in  FIG. 7C , one or more additional strain sensors—identified in  FIG. 7C  as the strain sensors  708   a  and  708   b  can be added into the diaphragm in order to measure strain induced by the bulging of the cushioning support  712 . 
     As with the flexible spacers described in reference to other embodiments, in many examples, the cushioning supports depicted in  FIGS. 7B-7C  can serve to increase the efficiency with which a load cell is manufactured and/or assembled. In particular, the cushioning supports can be disposed onto a compression plate (e.g., such as the second compression plate  704   b  depicted in  FIG. 7A ) in advance of attaching a diaphragm to supports extending from that compression plate. 
     In other words, the cushioning supports can form a substantially flat and/or planar receiving surface onto which a diaphragm can be placed during manufacturing of a load cell. In these embodiments, the cushioning support(s) and/or flexible spacer(s) can bond and/or otherwise couple and align the diaphragm (e.g., the diaphragm  706 ) to the second compression plate  704   b  (see, e.g.,  FIG. 7A ). As a result, a load cell, such as described herein, can be manufactured in a roll-to-roll process as a single component to be installed in an electronic device housing in a later process. 
     The foregoing embodiments depicted in  FIGS. 7A-7C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various implementations of a load cell incorporating one or more flexible spacers and/or cushioning supports. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a load cell including a flexible spacer and/or a cushioning support are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, a load cell such as described herein can include, without limitation: an array of flexible spacers disposed between a diaphragm and a compression plate; a flexible spacer disposed between a gap defined between a first compression plate and a second compression plate; a cushioning support disposed immediately below a region of a diaphragm that is positioned below a loading feature of a compression plate; and so on. 
     Furthermore, it may be appreciated that any suitable material can be used to construct a flexible spacer and/or a cushioning support, such as described herein. Suitable materials include, but are not limited to: foam strips; injected, curable foam; silicone strips; elastomeric strips; polymeric strips; pressure-sensitive adhesive; encapsulated liquids; gas bladders; and so on. Similarly, it may be appreciated that a flexible spacer and/or a cushioning support can be disposed and/or formed onto one or more surfaces of a load cell—such as described herein—in any number of suitable ways. Examples include: depositing uncured adhesive onto a surface of a compression plate and curing the uncured adhesive; depositing an adhesive foam strip into a surface of a compression plate; depositing a liquid or gel silicone or elastomer into a surface of a compression plate; and so on. In view of the various examples provided above, it may be appreciated that—for embodiments described herein—a flexible spacer and/or a cushioning support can be formed and/or deposited onto and/or into a load cell, such as described herein using any suitable technique, material, or combination of materials. 
     Still further load cell embodiments can be implemented in a different manner. For example, preceding embodiments include a first compression plate with a loading feature formed thereon and, additionally, a second compression plate with at least two supports formed thereon. This construction may not be required of all embodiments. For example, generally and broadly,  FIGS. 8A-8C  depict load cell embodiments in which a loading feature and/or a support can be attached, coupled, or otherwise affixed to (as opposed to being integrally formed with) a compression plate. 
       FIG. 8A  depicts a load cell  800   a  coupled to a surface  802  that, like other embodiments described herein, includes a compressible structure  804  defined by a first compression plate  804   a  and a second compression plate  804   b  separated by a gap so as to define a volume. The gap between the first compression plate  804   a  and the second compression plate  804   b  may be maintained and/or partially defined by a flexible spacer and/or a cushioning support, such as described in reference to  FIGS. 7A-7C , but this may not be required. For simplicity if illustration, the load cell  800   a  is depicted without a flexible spacer and without a cushioning support. 
     As with other embodiments described herein, the first compression plate  804   a  includes a loading feature  806  that extends into the volume and the second compression plate  804   b  includes two supports, identified as the supports  808 , that also extend into the volume. The supports define attachment points to couple to a diaphragm  810  that includes a strain sensor  812 . Optionally, the diaphragm  810  can be supported by a stiffener  814  or other backing plate (which may include one or more cutouts, such as described in reference to  FIGS. 4A-5C ). 
     In this embodiment, in contrast to other embodiments described herein, the loading feature  806  and the supports  808  are not integrally formed with the first compression plate  804   a  and the second compression plate  804   b , respectively. Instead, the loading feature  806  and the supports  808  are attached and/or otherwise coupled to the compression plates in a manufacturing process. The means by which the loading feature  806  and the supports  808  of the load cell  800   a  are coupled to the compression plates can differ from embodiment to embodiment. Example means of coupling the loading feature  806  and the supports  808  to the compression plates include, but are not limited to: adhesive; interference fit; welding; co-molding; mechanical fasteners; and so on, or any combination thereof. 
     In this example the loading feature  806  and the supports  808  of the load cell  800   a  can be formed from the same material as the compression plates, but this may not be required. For example, in some embodiments, the loading feature  806  and the supports  808  of the load cell  800   a  are formed from metal (e.g., aluminum, steel, magnesium, platinum, titanium, and so on) whereas in other embodiments, the loading feature  806  and the supports  808  of the load cell  800   a  are formed from plastic and/or acrylic. In some cases, the loading feature  806  and the supports  808  of the load cell  800   a  can be formed by depositing an uncured adhesive to a surface of a compression plate. After, optionally, allowing or encouraging the uncured adhesive to wet to the surface of the compression plate, the adhesive may be cured, thereby defining one or both the loading feature  806  and the supports  808  of the load cell  800   a.    
     In still further examples, a loading feature and/or a support of a load cell such as described herein can be formed in another manner. 
     For example  FIG. 8B  depicts a load cell  800   b  coupled to a surface  802  that, like other embodiments described herein, includes a compressible structure  804  defined by a first compression plate  804   a  and a second compression plate  804   b  separated by a gap so as to define a volume. The first compression plate  804   a  includes a loading feature  806  that extends into the volume and the second compression plate  804   b  includes two integrally-formed supports that also extend into the volume. As with other embodiments described herein, the supports define attachment points to couple to a diaphragm  810  that includes a strain sensor  812 . 
     In this embodiment, in contrast to other embodiments described herein, the loading feature  806  is not integrally formed with the first compression plate  804   a . Instead, in this example, the loading feature  806  is defined by a shim  814  that interposes the diaphragm  810  and the first compression plate  804   a . In many examples, the shim  814  is adhered/coupled to both the diaphragm  810  and the first compression plate  804   a  via adhesive, identified in the figure as the adhesive layers  816 . In other cases, the shim  814  may not be adhered to one or both of the diaphragm  810  or the first compression plate  804   a . For example, in these embodiments, the shim  814  may be held in place by friction. 
     The shim  814  can be formed from any number of suitable materials including, but not limited to: metal; plastic (e.g., poly-ethylene terephthalate, nylons, acrylic, other polymer materials); glass; and so on. The shim  814  can take any number of suitable shapes including, but not limited to: a cubic shape; a linear shape having a rectangular, polygonal, triangular, or other cross-section; a cylindrical shape oriented perpendicular to a length of the first compression plate  804   a ; a spherical shape; and so on. In some cases, more than one shim can be used (e.g., layered shims, adjacent shims, and so on). As may be appreciated, the thickness of the shim  814  may vary from embodiment to embodiment. 
     In still further examples, supports of a load cell, such as described herein, can also be formed with one or more shims. 
     For example  FIG. 8C  depicts a load cell  800   c  coupled to a surface  802  that, like other embodiments described herein, includes a compressible structure  804  defined by a first compression plate  804   a  and a second compression plate  804   b  separated by a gap so as to define a volume. The first compression plate  804   a  includes a loading feature  806  that extends into the volume and the second compression plate  804   b  includes two supports, identified as the supports  808 , that also extend into the volume. As with other embodiments described herein, the supports  808  define attachment points to couple to a diaphragm that includes a strain sensor. 
     In this embodiment, in contrast to other embodiments described herein, neither the loading feature  806  nor the supports  808  are integrally formed with the first compression plate  804   a . Instead, as with the embodiment described in reference to  FIG. 8B , the loading feature  806  is defined by a shim that interposes the diaphragm  810  and the first compression plate. Similarly, the supports  808  are each defined by a shim  820  that interposes the diaphragm  810  and the second compression plate  804   b.    
     As with the embodiment described in reference to  FIG. 8B , the shim  820  is adhered/coupled to both the diaphragm  810  and the second compression plate  804   b  via adhesive, identified in the figure as the adhesive layers  822 . In other cases, the shim  820  may not be adhered to one or both of the diaphragm  810  or the first compression plate  804   a . For example, in these embodiments, the shim  820  may be held in place by friction. 
     As with the shim  814  depicted in  FIG. 8B , the shim  820  can be formed from any number of suitable materials including, but not limited to: metal; plastic (e.g., poly-ethylene terephthalate, nylons, acrylic, other polymer materials); glass; and so on. The shim  820  can take any number of suitable shapes including, but not limited to: a cubic shape; a linear shape having a rectangular, polygonal, triangular, or other cross-section; a cylindrical shape oriented perpendicular to a length of the first compression plate  804   a ; a spherical shape; and so on. In some cases, more than one shim can be used (e.g., layered shims, adjacent shims, and so on). As may be appreciated, the thickness of the shim  820  may vary from embodiment to embodiment. 
     The foregoing embodiments depicted in  FIGS. 8A-8C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various implementations of a shim-based loading feature and/or a shim-based support. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a load cell including a loading feature and/or a support formed from a shim, separate from a compression plate, are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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. 
     More generally, it may be appreciated that the various embodiments described above can be selectively combined in a number of suitable ways. 
     For example,  FIG. 9A  depicts a load cell  900 , coupled to a surface  902 , that includes a compressible structure  904 . The compressible structure  904  includes a first compression plate  904   a  and a second compression plate  904   b  that are separated by a gap to define a volume in which a diaphragm  906  is disposed. The diaphragm  906  includes a strain sensor  908  that is disposed below a shim  910  interposing the first compression plate  904   a  and the diaphragm  906 . The shim  910  serves as a loading feature, such as described in reference to other embodiments presented herein. The diaphragm  906  is supported by two supports that are also defined by shims, identified as the shims  912 , that are disposed between the second compression plate  904   b  and the diaphragm  906 . In addition, the load cell  900  includes one or more flexible spacers and/or cushioning supports, identified as the flexible spacers  914 . 
     As a result of the depicted construction, a load cell—such as the load cell  900 —can be manufactured in a more efficient manner and at increased speed. In particular, it may be appreciated that the various functional features of the load cell  900  (e.g., the loading feature, the supports, the diaphragm, and so on) can all be deposited in a roll-to-roll process without substantive machining or manipulation. Further, it may be appreciated that more than one load cell can be manufactured in a row, such as shown in  FIG. 3A . In these examples, an array of load cells can be manufactured and/or assembled together at substantially the same time. Optionally, the array of load cells can be singulated in a subsequent manufacturing process to define individual components (each including one or more load cells) suitable for installation in an electronic device enclosure. 
     In some examples, an array of load cells can be manufactured as—and, optionally, singulated from—a single row of load cells, such as shown in  FIG. 3A . However, this is merely one example. In other cases, load cells can be manufactured in a two-dimensional array to be singulated into an appropriate one-dimensional or two-dimensional set of load cells in a later, optional, manufacturing process. 
     In still other examples, a strain sensor can be positioned over or relative to the supports of a load cell, such as described herein. 
     For example,  FIG. 9B —similar to the embodiment depicted in  FIG. 9A —depicts a load cell  900 , coupled to a surface  902 , that includes a compressible structure  904  including a first compression plate  904   a  and a second compression plate  904   b  that are separated by a gap to define a volume in which a diaphragm  906 , including a strain sensor  908 , is disposed. The strain sensor  908  is disposed below a shim  910  interposing the first compression plate  904   a  and the diaphragm  906 . As with the embodiment described in reference to  FIG. 9A , the shim  910  serves as a loading feature, such as described in reference to other embodiments presented herein. The diaphragm  906  is supported by two supports that are also defined by shims, identified as the shims  912 , that are disposed between the second compression plate and the diaphragm  906 . In addition, the load cell  900  includes one or more flexible spacers and/or cushioning supports, identified as the flexible spacers  914 . In this embodiment, the diaphragm  906  also includes two additional strain sensors, identified as the strain sensors  916 , that are disposed relative to the shims  912  of the load cell  900 . 
     As a result of the depicted construction, a load cell—such as the load cell  900 —can be manufactured in a more efficient manner and at increased speed. In particular, it may be appreciated that the various functional features of the load cell  900  (e.g., the loading feature, the supports, the diaphragm, and so on) can all be deposited in a roll-to-roll process without substantive machining or manipulation. In addition, it may be appreciated that the load cell  900  is axially symmetric (e.g., symmetric along a length of the load cell  900 ). In other words, the first compression plate  904   a  and the second compression plate  904   b  can be manufactured identically (and/or as a single part to be singulated into the first and second compression plates in a later operation). Upon assembly, the second compression plate  904   b  is offset from the first compression plate  904   a  by a distance approximately equal to one half of the length of the load cell  900 . 
     Further, as with the embodiment depicted and described in reference to  FIG. 9A , it may be appreciated that more than one load cell can be manufactured in a row, such as shown in  FIG. 3A . In these examples, an array of load cells can be manufactured and/or assembled together at substantially the same time. Optionally, the array of load cells can be singulated in a subsequent manufacturing process to defined individual components (each including one or more load cells) suitable for installation in an electronic device enclosure. 
     The foregoing embodiments depicted in  FIGS. 8A-8C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various implementations of a load cell, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments a load cell, are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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, although many preceding embodiments reference and depict a single load cell, it may be appreciated—as noted with respect to  FIG. 3A —that any number of suitable load cells can be contiguously manufactured and/or coupled to one another for a particular force input sensor implementation. Furthermore, although the embodiments described herein reference rectilinear load cells for a force input sensor to be incorporated into an enclosure sidewall of an electronic device, it may be appreciated that this is merely one example. Additional examples include, but are not limited to: load cells having a curved shape to couple to a curved sidewall of an electronic device; load cells having an arbitrary shape; load cells in which one compression plate is formed integrally with a sidewall of an electronic device; load cells of different size and/or shape formed contiguously and/or coupled to one another; load cells of different size and/or shape disposed at different locations within an electronic device housing; load cells disposed on opposite sides or edges of an electronic device enclosure; and so on, and/or any combination thereof. 
     As such, generally and broadly, it may be appreciated that a load cell of a force input sensor, such as described herein, can be configured in a number of suitable ways that may vary from embodiment to embodiment or implementation to implementation. 
     Similarly, the manner by which a measurement circuit of a force input sensor, such as described herein can couple to one or more strain sensor of a load cell can vary from embodiment to embodiment. Generally and broadly,  FIGS. 10A-10C  depict load cell sections of an example force input sensor that can be included in an electronic device such as the electronic device  100  depicted in  FIG. 1 . 
     For example,  FIG. 10A  depicts a load cell  1000   a  of a force input sensors such as described herein. The load cell  1000   a  includes a first compression plate  1002   a  separated from a second compression plate  1002   b  by a gap. A diaphragm  1004  is disposed in the gap between the compression plates and includes a strain sensor  1006 . As with other embodiments described herein, the diaphragm  1004  forms a three-point bending apparatus with two supports—identified as the supports  1008 —and a loading feature  1010 . As a result of this construction, when a force is applied to one or both of the first compression plate  1002   a  or the second compression plate  1002   b , the loading feature  1010  induces a bending moment in the diaphragm  1004 , causing the strain sensor  1006  to experience strain. 
     As noted with respect to other embodiments described herein, strain experienced by the strain sensor  1006  can be measured in a number of suitable ways by a number of suitable circuits, processors, or combinations thereof. For simplicity of description, the embodiments that follow reference an implementation in which a load cell—such as the load cell  1000   a —includes only a single, two-lead strain sensor that exhibits a change in resistance in response to strain. It may be appreciated, however, that this is merely one example and that other load cells can include multiple addressable and/or networked strain sensors that may include multiple leads and/or other connections to interface with a measurement circuit, such as described herein. 
     Continuing the example embodiment introduced above, a measurement circuit (not shown) can be electrically coupled to the strain sensor  1006 , and can be configured to measure the resistance of the strain sensor  1006  using any suitable technique. For simplicity of description, a measurement circuit is omitted from  FIG. 10A . In the illustrated example, the two leads of the strain sensor  1006 , identified as the leads  1012   a ,  1012   b  are depicted as vias and/or electrical traces defined within the loading feature  1010 . 
     In another embodiment, shown in  FIG. 10B , a load cell  900   b  (configured and labeled in the same manner as the load cell  900   a  of  FIG. 10A ), can include two leads, identified as the leads  1012   a ,  1012   b . In this example, a first lead  1012   a  is depicted as a via and/or an electrical trace defined within the loading feature  1010 . A second lead  1012   b  is depicted as a via and/or an electrical trace defined on a surface of the diaphragm  1004  and one of the supports  1008 . 
     In yet another embodiment, shown in  FIG. 10C , a load cell  900   c  (configured and labeled in the same manner as the load cell  900   a  of  FIG. 10A ), can include two leads, identified as the leads  1012   a ,  1012   b . In this example, a first lead  1012   a  is depicted as a via and/or an electrical trace defined within the loading feature  1010 . A second lead  1012   b  is depicted as a via and/or an electrical trace defined on a surface of the diaphragm  1004 . 
     The foregoing embodiments depicted in  FIGS. 10A-10C  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various techniques for electrically coupling a strain sensor of a load cell to an electrical circuit. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Generally and broadly,  FIGS. 11-13  depict simplified flow charts of example operations of methods of manufacturing a load cell and/or a load cell array for a force input sensor for an electronic device enclosure, such as described herein. It may be appreciated, however, that these simplified examples are not exhaustive and other methods of manufacturing, assembly, and construction may be used in other embodiments. 
       FIG. 11  is a simplified flow chart showing example operations of a method of manufacturing a load cell, such as described herein. The method  1100  includes operation  1102  in which a loading feature is defined and/or formed on a first compression plate, typically referred to herein as a compression plate. The method  1100  also includes operation  1104  in which a support feature is defined and/or formed onto a second compression plate, again, typically referred to herein as a compression plate. As noted with respect to other embodiments described herein, a loading feature and/or a support feature can be formed in a number of suitable ways including by, without limitation: machining a compression plate; ablating a compression plate; stamping a compression plate; and so on. 
     The method  1100  also includes operation  1106  in which a flexible substrate (also referred to herein as a “diaphragm”) onto the supports of the second compression plate. At operation  1108 , the loading feature of the first compression plate is aligned with a central region of the flexible substrate and, at operation  1110 , the first compression plate is coupled to the second compression plate. 
       FIG. 12  is a simplified flow chart showing example operations of a method of manufacturing a load cell, such as described herein. Similar to the method  1100  depicted in  FIG. 11 , the method  1200  includes operation  1202  in which a loading feature is adhered onto and/or coupled to a first compression plate (also referred to as a “compression plate”). 
     The method  1200  also includes operation  1204  in which a flexible spacer and/or a cushioning spacer is coupled to the first compression plate, adjacent to the loading feature. 
     The method  1200  also includes operation  1206  in which a support feature is adhered to or otherwise coupled to a second compression plate, again, typically referred to as a compression plate. As noted with respect to other embodiments described herein, a loading feature and/or a support feature can be coupled to the first or second compression plate in a number of suitable ways including by, without limitation: adhesive; welding; heat-staking; and so on. 
     The method  1200  also includes operation  1208  in which a flexible substrate (also referred to herein as a “diaphragm”) onto the supports of the second compression plate. At operation  1210 , the loading feature of the first compression plate is aligned with a central region of the flexible substrate and, at operation  1212 , the first compression plate is laminated to the second compression plate. 
       FIG. 13  is a simplified flow chart showing example operations of another method of manufacturing a load cell, such as described herein. The method  1300  includes operation  1302  in which a loading feature part is selected. In these embodiments, a loading feature part is understood to be a compression plate—such as described herein—having multiple loading features formed and/or coupled thereon. The method  1300  also includes operation  1304  in which a set of flexible spacers are disposed onto the loading feature part, between the loading features. In this manner, the flexible spacers partition the loading feature part. The method  1300  includes operation  1306  in which a support feature part is selected. In these embodiments, a support feature part is understood to be a compression plate—such as described herein—having multiple support features formed and/or coupled thereon. The method  1300  also includes operation  1308  in which a set of flexible spacers are disposed onto the support feature part, between the support features. In this manner, the flexible spacers partition the support feature part. The method  1300  also includes operation  1310  in which a flexible substrate (also referred to herein as a “diaphragm”) over the support features of the support feature part. Finally, at operation  1312 , the support feature part is coupled to the loading feature part. 
     The foregoing embodiments depicted in  FIGS. 11-13  and the various alternatives thereof and variations thereto are presented, generally, for purposes of explanation, and to facilitate an understanding of various configurations of a load cell array the various components thereof, such as described herein. However, it will be apparent to one skilled in the art that some of the specific details presented herein may not be required in order to practice a particular described embodiment, or an equivalent thereof. 
     Thus, it is understood that the foregoing and following descriptions of specific embodiments of a method of manufacturing a load cell or load cell array are presented for the limited purposes of illustration and description. These descriptions are not targeted to be exhaustive or to limit the disclosure to the precise forms recited herein. To the contrary, 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. 
     Further, one may appreciate that although many embodiments are disclosed above, that the operations and steps presented with respect to methods and techniques described herein are meant as exemplary and accordingly are not exhaustive. One may further appreciate that alternate step order or, fewer or additional operations may be required or desired for particular embodiments. 
     Although the disclosure above is described in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations, to one or more of the some embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments but are instead defined by the claims herein presented.

Metadata:
Filing Date: 20180829
Publication Date: 20200922
Grant Date: 20200922
Priority Date: 20180829
Inventors: DENG, ANDREW
OWENS, TRAVIS N.
MAJUMDAR, SHUBHADITYA
LIN, WEI
WANG, Ying-da
KOCH, TIMOTHY D.
GUPTA, NATHAN K.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1626", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04102", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1643", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1643", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1652", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1643", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 69639391