PATENT DOCUMENT

Publication Number: US-11487362-B1
Application Number: US-202016989657-A
Country: US
Kind Code: B1

Title: Enclosure with locally-flexible regions

Abstract:
A force input/haptic output interface for an electronic device can include a force input sensor and a haptic actuator. In one example, the force input sensor and the haptic actuator are accommodated on a frame positioned below an input surface. In many examples, the frame includes relieved portions that redirect and/or concentrate compression or tension in the haptic actuator into the frame.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a frame having a first section and a second section having reduced thickness relative to the first section; 
 a cover coupled to the frame, the cover having an interior surface and an external surface; 
 a sensor disposed on the interior surface; 
 a stiffener associated with the cover; and 
 a haptic output element; 
 wherein the second section and the haptic output element are spaced apart by a gap, the gap permitting the haptic output element to move toward the second section of the frame when an input is received at the external surface of the cover. 
 
     
     
       2. The electronic device of  claim 1 , wherein the external surface of the cover defines an input surface to receive the input and to provide haptic output. 
     
     
       3. The electronic device of  claim 1 , wherein the sensor is a capacitive touch sensor configured to detect a change in capacitance at the cover. 
     
     
       4. The electronic device of  claim 1 , further comprising a seal positioned between the frame and the interior surface of the cover, the seal inhibiting ingress of contaminants between the cover and the frame. 
     
     
       5. The electronic device of  claim 4 , wherein the seal is compressible to permit at least a portion of the cover to move relative to the frame. 
     
     
       6. The electronic device of  claim 1 , wherein the sensor is a first sensor and the electronic device further comprises a second sensor, the second sensor being a capacitive force sensor comprising two electrical contacts separated by a flexible material comprising at least one of a silicone, plastic, glass, or gel. 
     
     
       7. The electronic device of  claim 6 , wherein the second sensor is positioned between the first sensor and the stiffener. 
     
     
       8. The electronic device of  claim 1 , wherein the stiffener forms a locally-stiffened region at the cover. 
     
     
       9. The electronic device of  claim 1 , wherein the haptic output element is coupled to the stiffener. 
     
     
       10. The electronic device of  claim 1 , wherein a filler material is disposed within the gap. 
     
     
       11. The electronic device of  claim 10 , wherein the filler material comprises at least one of a foam, adhesive, liquid, or gas. 
     
     
       12. An electronic device comprising:
 a frame having a first section and a second section having reduced thickness as compared to the first section; 
 a cover coupled to the frame, the cover forming an interior surface and an external surface; 
 a first sensor disposed on the interior surface of the cover; 
 a haptic output element coupled to the second section of the frame and configured to bend the second section in response to an input to the external surface; and 
 a spacer positioned between the second section and the first sensor; 
 wherein the second section of the frame is bendable in a direction away from the cover. 
 
     
     
       13. The electronic device of  claim 12 , wherein the spacer is configured to deform to permit the first sensor to move relative to the second section when an input is received at the external surface of the cover. 
     
     
       14. The electronic device of  claim 13 , wherein the spacer comprises at least one of a silicone, plastic, glass, gel, or pressure-sensitive adhesive. 
     
     
       15. The electronic device of  claim 12 , further comprising a seal positioned between the frame and the interior surface of the cover, the seal inhibiting ingress of contaminants between the cover and the frame. 
     
     
       16. The electronic device of  claim 15 , wherein the seal is compressible to permit at least a portion of the cover to move relative to the frame. 
     
     
       17. The electronic device of  claim 12 , further comprising a second sensor configured to measure a force applied to the cover. 
     
     
       18. The electronic device of  claim 12 , further comprising a second sensor positioned between the spacer and the first sensor. 
     
     
       19. The electronic device of  claim 12 , further comprising drive circuitry in communication with the haptic output element, the drive circuitry is configured to actuate the haptic output element. 
     
     
       20. A keyboard comprising:
 a frame; 
 a cover coupled to the frame, the cover forming an interior surface and an external surface; 
 a seal positioned between the frame and the interior surface of the cover, the seal inhibiting ingress of contaminants between the cover and the frame; 
 a capacitive touch sensor disposed on the interior surface and configured to detect a change in capacitance at the cover; 
 a capacitive force sensor positioned adjacent the capacitive touch sensor, the capacitive force sensor comprising two electrical contacts separated by a flexible material; 
 a stiffener positioned adjacent the capacitive force sensor; and 
 a haptic output element coupled to the stiffener, the haptic output element being positioned to define a gap between the haptic output element and a reduced thickness section of the frame, the gap permitting the haptic output element to move toward the reduced thickness section of the frame when an input is received at the external surface of the cover.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This is a continuation of U.S. patent application Ser. No. 15/657,040, filed 21 Jul. 2017, entitled “ENCLOSURE WITH LOCALLY-FLEXIBLE REGIONS,” the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     Embodiments described herein relate to user interfaces for electronic devices, and in particular, to electronic device enclosures that include a distribution of locally-flexible regions that can be coupled to haptic actuators to provide haptic output to that user. 
     BACKGROUND 
     An input sensor for an electronic device can detect when a user applies a purposeful force, generally referred to as a “force input,” to a surface of the electronic device. Such sensors, together with associated circuitry and structure, can be referred to as “force input sensors.” 
     A mechanical actuator for an electronic device can generate a mechanical output, generally referred to as a “haptic output,” through a surface of the electronic device. Such actuators, together with associated circuitry and structure, can be referred to as “haptic actuators.” 
     In some cases, an electronic device can associate a force input sensor and a haptic actuator with the same surface, generally referred to as an “user interface surface.” Conventionally, a user interface surface, such as a trackpad of a laptop computer, extends through an opening defined in an enclosure of the electronic device. However, as a result of the opening, the enclosure of the electronic device may be undesirably structurally weakened, increasing manufacturing complexity and susceptibility of the electronic device to damage. 
     SUMMARY 
     Embodiments described generally reference an electronic device that includes a force input/haptic output interface integrated into, or associated with, an enclosure of the electronic device. More specifically, an electronic device such as described herein is positioned in an enclosure that has an external surface (which may be contiguous) and an interior surface opposite the external surface. In many embodiments, a frame, internal to the enclosure, is coupled to the interior surface. The frame includes a locally-flexible region that is defined, at least in part, by a reduced-thickness section and a support structure adjacent to reduced-thickness section. A force transducer (such as a piezoelectric element) is coupled to the support structure. As a result of this construction, an actuation of the force transducer induces a bending moment into the support structure to generate a haptic output through the external surface. 
     In some embodiments, more than one locally-flexible region and, correspondingly, more than one force transducer may be associated with the frame. In other embodiments, the frame may be integrated with the interior surface of the enclosure. In many examples, the enclosure is formed from glass, but this is not required. 
     Further embodiments described generally reference an electronic device including an enclosure formed from glass that accommodates a keyboard in an upper region of an external surface. The enclosure also accommodates a force input/haptic output interface (such as described herein) in a lower region of the external surface, generally below the keyboard. In these examples, locally-flexible regions may not be required; a haptic actuator or a piezoelectric element can be coupled directly to an interior surface of the lower portion of the external surface of the enclosure. 
    
    
     
       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 preferred 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 that can incorporate a force input/haptic output interface, such as described herein. 
         FIG. 2A  depicts an example distribution of locally-flexible regions defined into an interior surface of an electronic device, such as the electronic device of  FIG. 1 , that may be associated with a force input/haptic output interface. 
         FIG. 2B  depicts a locally-flexible region of the enclosure depicted in  FIG. 2A . 
         FIG. 2C  depicts another view of the locally-flexible region depicted in  FIG. 2B . 
         FIG. 2D  depicts a locally-flexible region of the enclosure depicted in  FIG. 2A , taken through line A-A. 
         FIG. 2E  depicts the locally-flexible region of the enclosure depicted in  FIG. 2D , showing flexion of the locally-flexible region. 
         FIG. 2F  depicts another example locally-flexible region of an enclosure, such as depicted in  FIG. 2A . 
         FIG. 2G  depicts the locally-flexible region of the enclosure depicted in  FIG. 2F , showing flexion of the locally-flexible region. 
         FIG. 3  depicts another example distribution of locally-flexible regions associated with a force input/haptic output interface. 
         FIG. 4  depicts another example distribution of locally-flexible regions associated with a force input/haptic output interface. 
         FIG. 5  depicts another example distribution of locally-flexible regions associated with a force input/haptic output interface. 
         FIG. 6A  depicts a cross-section of an example force transducer coupled to a locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 6B  depicts a cross-section of another example force transducer coupled to a locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 6C  depicts a cross-section of another example force transducer coupled to a locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 7  depicts another example distribution of locally-flexible regions associated with a force input/haptic output interface, such as described herein. 
         FIG. 8  depicts another example distribution of locally-flexible regions associated with a force input/haptic output interface, such as described herein. 
         FIG. 9  depicts a cross-section of an example force transducer coupled to a locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 10  depicts a cross-section of another example force transducer coupled to a locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 11  depicts a cross-section of another example force transducer and locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 12  depicts a cross-section of another example force transducer and locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 13  depicts a cross-section of another example force transducer and locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 14  depicts a cross-section of another example force transducer and locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 15  depicts a cross-section of another example force transducer and locally-flexible region of an interior surface of an electronic device enclosure, such as described herein. 
         FIG. 16  is a flow chart depicting example operations of a method of forming a haptic actuator, such as described herein. 
         FIG. 17  is a flow chart depicting example operations of a method of providing haptic feedback. 
         FIG. 18  is a flow chart depicting example operations of a method of receiving force input. 
     
    
    
     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 an electronic device that includes a force input/haptic output interface. The phrase “force input/haptic output interface,” as used herein, generally references a system or set of components configured to receive force input at a surface from a user and, additionally, to provide haptic output to that same user through the same surface. The surface associated with a force input/haptic output interface (such as described herein) can be referred to as an “user interface surface.” 
     In one example, a force input/haptic output interface is operated in conjunction with, and/or positioned over, a display of an electronic device. In this example, the user interface surface can be a protective outer cover (e.g., transparent glass, sapphire, plastic) positioned over an active display area of the display. A user can exert a force onto the protective outer cover to interact with content shown on the display at that location. In response, the force input/haptic output interface can generate a haptic output (e.g., click, vibration, shift, drop, pop, and so on) through or on the display at, or near, that location to inform the user that the force input was received. In other examples, one or more haptic outputs can be provided through the protective outer cover in response to, or independent of, one or more force inputs in a different or implementation-specific or configuration-specific manner. 
     In another example, a force input/haptic output interface is operated in conjunction with a user interface surface of an electronic device, such as a trackpad. In this example, the user interface surface is a continuous and planar external surface of the trackpad, which can be formed from an opaque or transparent material such as metal, glass, organic materials, synthetic materials, woven materials, and so on. A user can exert a force onto a portion of the user interface surface to instruct the electronic device to perform an action. In response, the force input/haptic output interface can generate a haptic output at, or near, that location to inform the user that the force input was received. As with other example configurations, one or more haptic outputs can be provided through the user interface surface in response to, or independent of, one or more force inputs in a different or implementation-specific or configuration-specific manner. 
     For simplicity of description, many embodiments that follow reference a force input/haptic output interface operated in conjunction with a non-display region of a portable electronic device, such as a trackpad region of a laptop computer. In these examples, the user interface surface is a contiguous external surface of the portable electronic device, although this may not be required. It may be appreciated, however, that this is merely one example; other configurations, implementations, and constructions are contemplated in view of the various principles and methods of operation, and alternatives thereto, described in reference to the embodiments that follow. 
     A force input/haptic output interface (such as described herein) can be implemented with one or more force input sensors and/or one or more haptic actuators. In some cases, a single component, referred to as a “force transducer,” can be configured to provide haptic output and to receive force input. For simplicity of description, certain embodiments that follow reference a force transducer, but it may be appreciated that this is merely one example construction; other embodiments may include separate force input sensors and haptic actuators. 
     A force input/haptic output interface can be implemented with a set of force transducers coupled to an interior surface of an enclosure of an electronic device. Actuation of a force transducer induces a haptic output through an exterior surface of the enclosure, opposite the interior surface. Similarly, a force applied to the exterior surface of the enclosure can locally deform the interior surface. In response to the local deformation, the force transducer can generate or change a signal in a manner corresponding to the local deformation. The signal, in turn, can be correlated to a force input (e.g., a magnitude, direction, and/or location of force applied to the exterior surface). 
     It may be appreciated that the thickness of the enclosure separating the interior surface from the exterior surface can affect one or more characteristics of a haptic output generated and/or one or more characteristics of a force input received. More specifically, the thicker the enclosure, the more attenuated haptic outputs and force inputs may be. 
     In many embodiments, an enclosure of an electronic device can be formed to a structural thickness sufficient to support, enclose, and/or contain components and elements of an electronic device. An interior surface of the enclosure can be defined by regions that are thinned, stiffened, or supported in a manner that confers specific mechanical properties to those regions of the interior surface, such as greater local flexibility or greater local stiffness. 
     In one example, an interior surface of an enclosure includes multiple locally-flexible regions. A locally-flexible region can include one or more cavities, openings, perforations, or reduced-thickness sections that at least partially surround (or circumscribe) and define a support structure (e.g., a fixed-fixed beam having two ends, each of which are constrained). A haptic actuator, as an example of a force transducer, can be coupled to the support structure such that compression or expansion of the haptic actuator (parallel or perpendicular to the interior surface) induces a bending moment (e.g., a deformation) in the support structure which, in turn, induces a haptic output through or on the external surface of the electronic device enclosure. The degree to which the support structure bends in response to actuation of the haptic actuator may be defined or controlled, at least in part, by the geometry of the reduced-thickness sections. 
     For example, the thinner a reduced-thickness section is, the more the support structure within the locally-flexible region may bend or otherwise deform. In some cases, a reduced-thickness section can include one or more openings or perforations, but this may not be required of all embodiments. In many embodiments, the reduced-thickness sections have a thickness that is less than the support structure and less than the enclosure. In some examples, the support structure may have a thickness that is less than a thickness of the enclosure, but this may not be required of all embodiments. In still further embodiments, locally-flexible regions may not be required and a force transducer may be coupled directly to the interior surface of the electronic device enclosure. 
     In still further embodiments, the enclosure may have a substantially constant thickness. In these examples, the enclosure may be locally strengthened by a frame coupled to the interior surface of the enclosure. In this manner, regions of the interior surface of the enclosure that are not coupled to the frame may be more flexible (e.g., locally-flexible) than regions that are supported by the frame. 
     These and other embodiments are discussed below with reference to  FIGS. 1-18 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanation only and should not be construed as limiting. 
       FIG. 1  shows an electronic device  100  that can include a force input/haptic output interface, such as described herein. As with other embodiments, the force input/haptic output interface can be configured to receive force input from a user and to provide haptic output to that same user. In some examples, the force input/haptic output interface is associated with a display of the electronic device  100 . For example, the force input/haptic output interface may be positioned behind or along a perimeter of the display. In other examples, the force input/haptic output interface is associated with an input area of an enclosure the electronic device  100 , such as a trackpad area adjacent to a keyboard area of an enclosure of a laptop computer. 
     For simplicity of description and illustration, the electronic device  100  is depicted in  FIG. 1  as a laptop computer having a force input/haptic output interface integrated into a trackpad. However, it may be appreciated that this is merely one example and that other implementations of force input/haptic output interfaces can be integrated into, associated with, or take the form of different components or systems of other electronic devices including, but not limited to: desktop computers; tablet computers; cellular phones; wearable devices; peripheral devices; input devices; accessory devices; cover or case devices; industrial or residential control or automation devices; automotive or aeronautical control or automation devices; a home or building appliance; a craft or vehicle entertainment; control; and/or information system; a navigation device; and so on. 
     In the illustrated example, the electronic device  100  includes an enclosure  102  to retain, support, and/or enclose various electrical, mechanical, and structural components of the electronic device  100 , including a primary display  104 , a keyboard  106 , and a secondary display  108 . The enclosure  102  can be formed from, as an example, glass, sapphire, ceramic, metal, or plastic, or any combinations thereof. The electronic device  100  can also include a processor, memory, power supply and/or battery, network connections, sensors, input/output ports, acoustic elements, haptic actuators, digital and/or analog circuits for performing and/or coordinating tasks of the electronic device  100 , and so on. For simplicity of illustration, the electronic device  100  is depicted in  FIG. 1  without many of these elements, each of which may be included, partially and/or entirely, within the enclosure  102  and may be operationally, structurally, or functionally associated with, or coupled to, the primary display  104 , the keyboard  106 , the secondary display  108 , and/or a force input/haptic output interface  110 . 
     The force input/haptic output interface  110  includes a set of force transducers distributed relative to a user interface surface that may be touched by a user. In the illustrated embodiment, the user interface surface is positioned in, or projects from, a rectangular opening defined through a lower portion of the enclosure  102 . In other embodiments, the user interface surface can extend across the width of the lower hinged portion of the enclosure  102 . In still further embodiments, the opening and/or user interface surface can take another shape. 
     In the illustrated example, the user interface surface associated with the force input/haptic output interface  110  is separate from the enclosure  102 . More particularly, the user interface surface is positioned in an opening defined through the enclosure  102 . The opening is depicted as a rounded rectangle, but may take any suitable shape. 
     The user interface surface can be formed from any number of suitable materials. In some examples, the user interface surface is formed from the same material (or a similar material) as the enclosure  102 , but this may not be required. For example, in one embodiment, the enclosure  102  is formed from metal and the user interface surface is formed from glass. In another example, the enclosure  102  is formed from glass and the user interface surface is formed from a ceramic material. In other examples, the user interface surface may be integrated into the enclosure  102 . In many examples, the user interface surface is associated with another interface or input system of the electronic device  100 , such as a touch input system. 
     In some cases, the user interface surface can be integrated into or otherwise be a part of the enclosure  102 . In other words, an opening defined through the enclosure  102 , such as shown, does not exist; the set of force transducers associated with the force input/haptic output interface  110  is coupled directly to an interior surface of the enclosure  102 . 
     Each force transducer of the set of force transducers associated with the force input/haptic output interface  110  can be arranged relative to the user interface surface in a number of ways. For example, in some embodiments, the set of force transducers is arranged in a grid and includes four separate force transducers. In other cases, the set of force transducers contains five separate force transducers arranged in multiple, offset, rows. In some cases, each force transducer has the same shape, whereas in others certain force transducers may be larger or smaller than others. More or fewer force transducers may be use in any configuration and/or embodiment described herein. 
     Similarly, each force transducer associated with the force input/haptic output interface  110  can be coupled to the user interface surface in any of a number of ways. For example, in some embodiments, each force transducer is coupled directly to the user interface surface using an adhesive. In other cases, each force transducer is coupled to a substrate (e.g., a glass sheet) or frame that, in turn, is coupled to the user interface surface. 
     Generally and broadly,  FIGS. 2A-6C  depict various example constructions of a force input/haptic output interface. More specifically, these embodiments generally take the form of a force input/haptic output interface that includes haptic actuators that are coupled to locally-flexible regions defined into an interior surface of an electronic device enclosure. In these embodiments, the locally-flexible regions are each defined, at least part, by a reduced-thickness section that in turn defines a complete or partial perimeter of a support structure that is coupled to a haptic actuator. In this manner, actuation of the haptic actuator induces a bending moment and/or other deformation in the support structure. 
     In one example, a locally-flexible region includes two parallel rectilinear reduced-thickness sections defining a support structure between them. In this manner, the support structure takes the form of a bending beam that is fixed on two ends. In this example, the support structure has a thickness greater than that of the reduced-thickness sections, but this may not be required of all embodiments. 
     In another example, a locally-flexible region includes two parallel rectilinear openings or apertures defining a support structure between them. In other words, the two rectilinear openings are aligned with each other and offset from each so as to define a support structure having particular flexibility or rigidity. In this manner, the support structure takes the form of a bending beam that is fixed on two ends. 
     In another example, a locally-flexible region includes one reduced-thickness section that defines three edges of a rectilinear a support structure. In this manner, the support structure takes the form of a cantilevered beam that is fixed on one end. 
     In yet another example, a locally-flexible region includes four reduced-thickness sections arranged in a grid, defining a cross-shaped support structure between them. In yet another example, a locally-flexible region includes curved reduced-thickness sections. In yet another example, a locally-flexible region includes a number of perforations in place of a reduced-thickness section. In yet another example, a locally-flexible region includes a reduced-thickness section that entirely circumscribes a support structure. In this manner, the support structure takes the form of an island surrounded entirely by a reduced-thickness section. 
     Accordingly, generally and broadly, a locally-flexible region such as described herein typically includes at least one reduced-thickness section (that may be or include an aperture) that defines at least a portion of a perimeter of a beam or support structure. A haptic actuator is typically coupled to the beam or support structure. 
     For simplicity of description and illustration, the embodiments that follow reference one example construction of a locally-flexible region including two substantially parallel rectilinear reduced-thickness sections defining a support structure between them. It may be appreciated, however, that this is not required and a reduced-thickness section (or aperture or opening) and/or a locally-flexible region can be suitable configured differently in different embodiments. 
     For example,  FIG. 2A  depicts an example distribution of locally-flexible regions formed or defined into an interior surface of an enclosure. The local-flexible regions are shown in dashed lines as these regions are not normally visible in the view depicted in  FIG. 2A . The locally-flexible regions can be associated with a force input/haptic output interface incorporated into an electronic device  200 . In particular, the electronic device  200  includes an enclosure  202  that defines an external surface  204 . The external surface  204  may be associated with a respective interior surface of the enclosure  202 . The external surface  204  may be contiguous and planar, although this is not required. 
     In the illustrated embodiment, the external surface  204  is shown with a region that generally extends parallel to a length of a keyboard, such as shown in  FIG. 1 , although this configuration is not required. In other embodiments, the external surface  204  can be configured in another manner. 
     For example, in other cases, the external surface  204  can be defined elsewhere, relative to the enclosure  202 . For example, the external surface  204  may be associated with a portion of the enclosure  202  generally above the depicted keyboard (as used herein terms such as “above” and “below” are relative to a typical orientation of an electronic device, such as the electronic device  200 , when in use). In other cases, the external surface  204  may be below the enclosure  202 , on an underside of the electronic device. In still other cases, the external surface  204  may be defined in a sidewall or edge of the enclosure  202 . It may be appreciated that the external surface  204 , associated with the force input/haptic output interface, can be suitable configured in or incorporated into any suitable surface of the enclosure  202 . 
     In this embodiment, the external surface  204  defines an opening to accommodate a user interface surface  206 , which may be formed from a different material than the external surface  204 . The opening is aligned approximately in the center of the first region (e.g., a lower region) of the external surface  204  and extends approximately half a width of the lower region. 
     In the illustrated embodiment, four locally-flexible regions  208 ,  210 ,  212 ,  214  are illustrated in phantom and defined into the interior surface of the enclosure  202 . The four locally-flexible regions are distributed in a two-by-two grid. 
     The four locally-flexible regions are typically configured and constructed in the same manner, but this is not required. For example, in some embodiments, the locally-flexible region  208  and the locally-flexible region  210  are configured as a first pair of locally-flexible regions sharing one or more flexibility or rigidity properties, whereas the locally-flexible region  212  and the locally-flexible region  214  are configured as a second pair of locally-flexible regions sharing one or more flexibility or rigidity properties that are different than the properties of the first pair. For simplicity of description, the description that follows references the locally-flexible region  208 ; it is appreciated that the locally-flexible regions  210 ,  212 , and  214  may be similarly configured. 
     Turning to  FIGS. 2B-2E , the locally-flexible region  208  defines a support structure  216  to support a haptic actuator  218 , such as a piezoelectric element. The support structure  216  is bordered by two reduced-thickness sections, identified as the reduced-thickness sections  220   a  and  220   b . The reduced-thickness sections  220   a  and  220   b  have a thickness less than that of the enclosure  202  and less than that of the support structure  216 . The reduced-thickness sections  220   a  and  220   b  can be formed into the interior surface of the enclosure  202  in any suitable manner including, but not limited to: ablation; etching; stamping; scribing; and so on. In some examples, the reduced-thickness sections  220   a  and  220   b  include one or more apertures or perforations (not shown). The interior surface of the enclosure  202  is identified in  FIGS. 2B-2C  as the interior surface  222 . 
     In the illustrated example, and as shown in  FIGS. 2B-2C , the support structure  216  is a rectilinear bending beam with two fixed ends, a first end  216   a  and a second end  216   b . (see, e.g.,  FIG. 2A  and  FIGS. 2D-2E ). However, this is merely one example. In other embodiments, the support structure  216  can take any number of suitable shapes including, but not limited to: a cross shape; a circular shape; a curved shape; a spoke-and-hub shape; and so on. 
     In some cases, the support structure  216  can have a thickness that is less than that of the enclosure  202  and/or the user interface surface  206 , although this may not be required. For example, as illustrated (see  FIGS. 2B-2C ), the support structure  216  has a thickness less than that of the enclosure  202 . 
     As a result of this construction, compression or expansion of the haptic actuator  218  in a direction parallel to the user interface surface  206  induces a bending moment, deforming either toward the user interface surface  206  or toward an interior volume within the enclosure  202 , in the support structure  216 .  FIG. 2E  depicts an outward deformation of the user interface surface  206  as a result of a compression of the haptic actuator  208 . More specifically, parallel compression of the haptic actuator  208  (e.g., parallel to the user interface surface  206 ) results in perpendicular deformation of the user interface surface  206 . In other cases, the user interface surface  206  may deform inwardly. In still other embodiments, the user interface surface  206  may deform both outwardly and inwardly (e.g., oscillation or vibration). 
     In another example, the haptic actuator  218  can compress or expand in a direction perpendicular to the user interface surface  206 . For example, as illustrated in  FIG. 2F , an enclosure  224  can include a locally-flexible region  226  of an external user interface surface. The locally-flexible region  226  can be positioned opposite an internal frame  228 . A haptic actuator  230  is positioned between the internal frame  228  and the locally-flexible region  224 . 
     As a result of this construction, compression or expansion of the haptic actuator  230  in a direction perpendicular to the locally-flexible region  226  induces a bending moment, deforming the locally-flexible region  226  either outward or, alternatively, toward an interior volume within the enclosure  224 , in the support structure  216 .  FIG. 2G  depicts an outward deformation of the locally-flexible region  226  as a result of an expansion of the haptic actuator  230 . More specifically, perpendicular expansion of the haptic actuator  230  (e.g., perpendicular to the locally-flexible region  226 ) results in perpendicular deformation of the locally-flexible region  226 . In other cases, the locally-flexible region  226  may deform inwardly. In still other embodiments, the locally-flexible region  226  may deform both outwardly and inwardly (e.g., oscillation or vibration). 
     Other embodiments can be implemented in another manner. For example,  FIG. 3  depicts another example distribution of force transducers, each associated with a respective locally-flexible region defined into an interior surface of the enclosure, and that can be associated with a force input/haptic output interface incorporated into an electronic device  300 . In particular, the electronic device  300  includes an enclosure  302  that defines an external surface  304 . The external surface  304  defines an upper region and a lower region. In this embodiment, the external surface  304  defines the user interface surface; no opening or separate layer to define the interface is required. In this manner, the visual continuity of the external surface  304  is not interrupted. The locally-flexible regions can be formed into an interior surface of the enclosure  302  below the lower region of the external surface  304 . 
     In the illustrated embodiment, the interior surface of the enclosure  302  defines ten locally-flexible regions associated with ten force transducers, arranged in two parallel rows (e.g., each local-flexible region positioned in a selected location). One of the force transducers is labeled as the force transducer  306 . As with other embodiments described herein, the force transducer  306  is coupled to a locally-flexible region defined into the interior surface of the enclosure  302 . In some embodiments, the locally-flexible region is defined into or defined by a frame coupled to the interior surface of the enclosure  302 . 
     In the illustrated example, the frame includes reduced-thickness sections that cooperate to define a rectilinear bending beam (identified as the support structure  308 ) having two fixed ends, identified as the fixed ends  308   a  and  308   b . In the illustrated embodiment, the reduced-thickness sections are identified as the reduced-thickness sections  310   a  and  310   b . In this manner, the frame defines locally-flexible region similar to the local-flexible regions referenced with respect to other embodiments described herein. 
     A piezoelectric element  312  is positioned on the support structure  308 . In other embodiments, the support structure  308  can take any number of suitable shapes including, but not limited to: a cross shape, a circular shape, a curved shape, a spoke-and-hub shape, and so on. 
     As a result of the depicted construction, compression or expansion of the piezoelectric element  318  induces a bending moment within the support structure  308 , either toward the external surface  304  of the enclosure  302  or toward an interior volume within the enclosure  302 . 
     Still further embodiments can be implemented in another manner. For example,  FIG. 4  depicts an electronic device  400  that includes another example distribution of force transducers that can be associated with a force input/haptic output interface. In particular, the electronic device  400  includes an enclosure  402  that defines a user interface surface  404  that extends across an entirety of a width of a lower portion of the enclosure  402 , substantially parallel to a length of a keyboard positioned in an upper portion of the enclosure  402 . 
     In the illustrated embodiment, the interior surface of the enclosure  402  includes two parallel rows of locally-flexible regions, identified as the upper row  406  and the lower row  408 . In this example, the lower row  408  can include locally-flexible regions that have different mechanical properties than the locally-flexible regions of the upper row  406 . In particular, the locally-flexible regions of the lower row  408  may be more rigid (e.g., smaller in area) than the locally-flexible region of the upper row  406 . 
     Still other configurations and constructions may be implemented. For example,  FIG. 5  depicts an electronic device  500  with another example distribution of force transducers. The electronic device  500  includes an enclosure  502  that defines a user interface surface  504 . In the illustrated embodiment, a set of locally-flexible regions defined into the internal surface of the enclosure  502  supports a number of force transducers, arranged in three parallel rows, one of which is identified as the row  506 . 
     As noted above with respect to other embodiments, the locally-flexible regions are typically configured and constructed in the same manner, but this is not required. For example, in some embodiments, the row  506  may include a locally-flexible region that exhibit different mechanical properties. For example, a first locally-flexible region  508  may include with a cantilevered  510  (e.g., a cantilevered beam) that is defined by a reduced-thickness section  512 . A second locally-flexible region  514  may be associated with a pair of reduced-thickness sections that cooperate to define a rectilinear bending beam having two fixed ends, such as described with respect to other embodiments herein. 
     In this example, each row of force transducers includes the same number of force transducers, but configuration this is not required. For example, in some embodiments, different rows of force transducers may include a different number or arrangement of force transducers. 
     The foregoing embodiments depicted in  FIGS. 2A-5  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 force input/haptic output interface 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, it may be understood that, generally and broadly, embodiments described herein can arrange any suitable number of force transducers in any number of suitable patterns including, but not limited to: grid patterns; column-and-row patterns; alternating patterns; repeating patterns; tessellated patterns; offset patterns; and so on. Further, it may be appreciated that in certain examples, locally-flexible regions may be included to define or modify particular load paths through a frame supporting the various force transducers or an interior surface of an electronic device enclosure that supports the various force transducers. In other embodiments, the locally-flexible regions are associated with reduced-thickness sections (e.g., formed by abrasion, ablation, etching, molding, and so on). 
     Further, it may be understood that, although the foregoing embodiments reference force transducers implemented with piezoelectric elements, this configuration is not required. In other embodiments, other electroactive elements, materials, or constructions may be used. Suitable materials and constructions may include, without limitation: electroactive polymers; shape-change or memory-wire (e.g., nitinol); ferroelectric polymers; microelectromechanical systems; magnetic attractors; linear actuators; solenoid-based systems; and so on. 
     Further, in many examples, the support structures depicted and described in reference to  FIGS. 2A-5  may not share a uniform thickness with adjacent portions of the interior surface of an electronic device enclosure. For example,  FIGS. 6A-6C  generally and broadly depict cross-sections of an example force transducer coupled to a locally-flexible region, such as a frame or an interior surface of an electronic device enclosure. 
     In particular,  FIG. 6A  depicts a cross-section of an example force transducer  600   a  coupled to a locally-flexible region  602  of an enclosure, such as described herein. The cross-section is taken through line A-A of  FIG. 2A , and shows an embodiment different than that of  FIGS. 2B-2E . The locally-flexible region  602  includes a relieved section  604  that forms a support structure. The relieved section  604  has a thickness less than that of portions of the locally-flexible region  602  adjacent to the relieved section  604 . 
     The relieved section  604  can be formed in any number of suitable ways. For example, the relieved section  604  can be formed by laser ablation, mechanical etching, chemical etching, or any combination thereof. A piezoelectric element  606  is coupled to the relieved section  604  such that compression or expansion of the piezoelectric element  606  induces a bending moment in the relieved section  604 . Similarly, bending of the relieved section  604  can result in a concentration of compression or tension in the piezoelectric element  606 . 
       FIG. 6B  depicts a cross-section of an example force transducer  600   b  coupled to a locally-flexible region  602 , such as described herein. The locally-flexible region  602  includes a first relieved section  610  opposite a second relieved section  612  (e.g., different surface of an enclosure). More specifically, the first relived section  610  may be defined into an external surface of a housing and the second relived section may be defined into an internal surface of the housing. The combination of the first relieved section  610  and the second relieved section  612  results in a thickness less than that of portions of the locally-flexible region  602  adjacent to those sections. 
     The relieved sections can be formed, and may function, as described with respect to other embodiments described herein (e.g.,  FIGS. 2A-5 ). 
     Although illustrated as opposite one another, one may appreciate that the first relieved section  610  and the second relieved section  612  need not be symmetrically formed. For example, in some embodiments, the second relieved section  612  may be wider than the first relieved section  610 . In other cases, the second relieved section  612  may only partially overlap the first relieved section  610 . 
     In still further embodiments, a locally-flexible region can be formed by stiffening or supporting one substrate layer (e.g., an outer layer of an electronic device enclosure) with a second substrate layer. For example,  FIG. 6C  depicts a cross-section of another example force transducer coupled to a locally-flexible region. The locally-flexible region  600   c  is defined by a substrate layer  614  that is strengthened by a backing plate  616 . In some embodiments, the backing plate can be referred to as a “frame” that provides mechanical support to the substrate layer  614 . The backing plate  616  increases the thickness of certain portions of the substrate layer  614 . In this manner, a relieved section is formed. The relieved section is coupled to a piezoelectric element  606 , as with previously-discussed embodiments. 
     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 constructions and distributions of force transducers (and, correspondingly, force input sensors and haptic output elements) 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. 
     Generally and broadly,  FIGS. 7-8  depict various example constructions of a force input/haptic output interface. Each depicts a different example arrangement of force transducers relative to a user interface surface. 
     For example,  FIG. 7  depicts an example distribution of force transducers that can be associated with a force input/haptic output interface incorporated into an electronic device  700 . In particular, the electronic device  700  includes an enclosure  702  that defines an external surface  704 . In this embodiment, as with the embodiment depicted in  FIG. 2 , the external surface  704  defines an opening to accommodate a user interface substrate  706 . In some examples, the user interface substrate  706  and the external surface  704  may be flush, but this may not be required of all embodiments. For example, in some implementations, the user interface substrate  706  protrudes from the external surface  704 . 
     In some embodiments, the user interface substrate  706  can be coupled to a frame (not shown) that is disposed within the enclosure  702 . The frame can be made from any number of suitable materials including metals, plastics, glasses, and so on. In one example, the frame is coupled (e.g., via fasteners, adhesive, and so on) to an internal surface of the enclosure  702 . 
     In the illustrated embodiment, the frame supports four force transducers  708 ,  710 ,  712 , and  714 . The four force transducers are arranged in a two-by-two grid. 
     The four force transducers are typically configured and constructed in the same manner, but this is not required. For example, in some embodiments, the force transducer  708  and the force transducer  710  are configured as a first pair of transducers sharing one or more properties whereas the force transducer  712  and the force transducer  714  are configured as a second pair of transducers sharing one or more properties different than the properties of the first pair. For simplicity of description, the description that follows references the force transducer  708 ; it is appreciated that the force transducers  710 ,  712 , and  714  may be similarly configured. 
     The force transducer  708  is formed from a piezoelectric material having a crystalline structure that mechanically distorts when an electric field is applied to it. Suitable materials can include lead zirconate titante and potassium sodium niobate. In other examples, the force transducer  708  can be formed from an electroactive polymer, an electromagnetic coil and a ferromagnetic or magnetic plate, or an any combination thereof. 
     As a result of this construction, compression or expansion of the force transducer  708  induces a deformation in the user interface substrate  706 . Similarly, a compression of the suspended of the user interface substrate  706  induces a compression of the force transducer  708 . 
     In other embodiments, one or more force transducers of a force input/haptic output interface can be distributed in a different manner. For example,  FIG. 8  depicts another sample force input/haptic output interface incorporated into an electronic device  800 . In particular, the electronic device  800  includes an enclosure  802  that includes two rows of force transducers (or haptic actuators or force input sensors), identified as the upper row  804  and the lower row  806 . The upper row  804  and the lower row  806  are coupled to an interior surface of the enclosure, generally below a keyboard. The two rows, as illustrated, each include four force transducers. 
     The foregoing embodiments depicted in  FIGS. 7-8  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 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, it may be understood that, generally and broadly, embodiments described herein can arrange any suitable number of force transducers in any number of suitable patterns including, but not limited to: grid patterns; column-and-row patterns; alternating patterns; repeating patterns; tessellated patterns; offset patterns, and so on. 
     Further, it may be understood that although the foregoing embodiments reference force transducers implemented with piezoelectric elements, this configuration is not required; in other embodiments, other electroactive elements, materials, or constructions may be used. Suitable materials and constructions may include, without limitation: electroactive polymers; shape-change or memory-wire (e.g., nitinol); ferroelectric polymers; microelectromechanical systems; magnetic attractors; linear actuators; solenoid-based systems; and so on. 
     Further, as with other embodiments described herein, the force transducers depicted and described in reference to  FIGS. 7-8  may not share a uniform thickness with adjacent portions of the frame or the interior surface of an electronic device enclosure. For example, a locally-flexible region can be formed by stiffening or supporting one substrate layer with a second substrate layer. For example,  FIG. 9  depicts a cross-section taken through line B-B of  FIG. 7 , showing another example force transducer coupled to a locally-flexible region. The locally-flexible region  900  is defined by a substrate layer  902  that can couple to a force transducer  904 . The substrate layer  902  is strengthened by a backing plate  906 . The backing plate  906  increases the thickness of certain portions of the substrate layer  902 , thereby forming a relieved section  908 . 
     In further examples, a force input/haptic output interface can be integrated within an electronic device in another manner. For example, as noted above, a force input/haptic output interface may be implemented in conjunction with a touch input sensor.  FIGS. 10-14  depict examples of such configurations. 
     For example,  FIG. 10  depicts a cross-section (e.g., taken through line B-B of  FIG. 7 , showing a different embodiment than that of  FIG. 9 ) of an example force input/haptic output interface. In this example, the force input/haptic output interface  1000  includes a force input sensor and a haptic output element. 
     The force input/haptic output interface  1000  is associated with an external cover  1002  that defines an input surface to receive user input (e.g., force and touch) and to provide haptic output. The external cover  1002  is positioned over and coupled to a frame  1004  via a compressible seal  1006 . The compressible seal  1006  can provide relief to the external cover  1002  when a user applies a force to the external cover  1002 . In other cases, the compressible seal  1006  provides an environmental or hermetic seal to protect one or more components internal to the force input/haptic output interface  1000 . In the illustrated example, a touch input sensor  1008  is disposed on an interior surface of the external cover  1002 . 
     The force input/haptic output interface  1000  also includes a haptic actuator  1010  that is coupled to a reduced-thickness section of the frame  1004 , identified as the reduced-thickness section  1004   a . More specifically, the haptic actuator  1010  is coupled to a lower surface of the reduced-thickness section  1004   a . As with other embodiments described herein, the haptic actuator  1010  can include a piezoelectric element. 
     The frame  1004  can be configured to provide mechanical support to one or more portions of the force input/haptic output interface  1000 . In other examples, the frame  1004  can provide a means of coupling the external cover  1002  to functional portions of the force input/haptic output interface  1000 . More specifically, the frame  1004  can include one or more surfaces configured to adhere to one or more surfaces of the external cover  1002 . 
     The material or construction of the frame  1004  may be selected at least in part to provide a particular haptic output in response to a compression or deformation of the haptic actuator  1010 . For example, a thickness of the frame  1004  can influence one or more characteristics of a haptic output generated by the haptic actuator  1010  that is coupled to that frame; a thicker frame may result in attenuation of low frequency outputs from the haptic actuator  1010  whereas a thinner frame may result in attenuation of high frequency outputs from the haptic actuator  1010 . 
     Similarly, the material of the frame  1004  can influence one or more characteristics of a haptic output generated by the haptic actuator  1010  that is coupled to that frame. For example, an aluminum frame may result in a different haptic output than a copper frame, a plastic frame, or a glass frame. 
     In many embodiments, the frame  1004  is formed from a different material than the external cover  1002 . For example, the frame  1004  can be formed from metal and the external cover  1002  can be formed from glass. 
     The force input/haptic output interface  1000  also includes a capacitive force sensor  1012 . The capacitive force sensor  1012  can be defined by two or more electrical contacts separated by a flexible material such as, but not limited to: silicone; plastic; glass; gel; and so on. In some cases, the flexible material of the capacitive force sensor  1012  may have a non-Newtonian response such that when the frame  1004  deforms in response to an actuation of the haptic actuator  1010 , the deformation of the frame  1004  is rigidly translated to the external cover  1002 . 
     The flexible material of the capacitive force sensor  1012  need not be continuous; in the illustrated example, the flexible material is implemented as three separate flexible dot elements, but this is not required. As a result of this construction, when a force is applied (e.g., by a user) to the external cover  1002 , the flexible material of the capacitive force sensor  1012  can compress, reducing the distance between the two or more electrical contacts and changing the capacitance of the capacitive force sensor  1012 . This change in capacitance can be measured by a controller (that can include drive circuitry, sense circuitry, and the like) coupled to or otherwise in electrical communication with the capacitive force sensor  1012 , which in turn, can correlate the capacitance change (or absolute capacitance) to a magnitude of force applied by the user to the external cover  1002 . In still further examples, the capacitive force sensor  1012  can provide mechanical relief to the external cover  1002 . 
     In this example, the haptic actuator  1010  can be configured to provide haptic output to a user and the force sensor  1012  can be configured to receive force input from the same user. 
     In another embodiment, the force input/haptic output interface can be implemented in a different manner. For example,  FIG. 11  depicts a cross-section of a force input/haptic output interface  1100 , such as described herein. In this embodiment, the force input/haptic output interface  1000  includes a touch input sensor, a force input sensor, and a haptic output element. In this example, the haptic output element is positioned below the force input sensor. 
     As with other embodiments described herein, the force input/haptic output interface includes an external cover  1102  that defines an input surface to receive user input and to provide haptic output. The external cover  1102  is positioned over and coupled to a frame  1104  via a compressible seal  1106 , that may be configured and function similarly to compressible seals described in reference to other embodiments herein. A touch input sensor  1108  is disposed on an interior surface of the external cover  1102 . The touch input sensor  1108  can be implemented as a capacitive touch sensor. 
     As with other embodiments described herein, the force input/haptic output interface  1100  also includes a capacitive force sensor  1110 . The capacitive force sensor  1110  can be defined by two electrical contacts separated by a flexible material such as, but not limited to: silicone, plastic, glass, gel, and so on. The flexible material need not be continuous; in the illustrated example, the flexible material is implemented as a flexible contiguous layer, but this is not required. 
     The force input/haptic output interface  1100  also includes a stiffener  1112  below the capacitive force sensor  1110 . The stiffener  1112  can be configured and can function similar to stiffeners and backing plates described herein. In particular, the stiffener  1112  may define locally-flexible and/or locally-stiffened regions of the force input/haptic output interface  1100 . 
     A haptic output element  1114  is positioned below the stiffener  1112 . The haptic output element  1114  is separated from the frame  1104  by a gap  1116 . The gap  1116  is configured to permit the force input/haptic output interface  1100  to flex in response to a force applied by a user or a haptic output generated by the haptic output element  1114 . In other examples, the gap  1116  can be larger or smaller. The gap  1116  may have a uniform or non-uniform thickness. In some cases, the gap  1116  can be filled with a filler material such as, but not limited to: compressible foam; compressible adhesive; compressible liquid; and so on. In other cases, the gap  1116  may be filled with a gas such as air. 
       FIG. 12  depicts a cross-section of another example force transducer coupled to a substrate associated with a force input/haptic output interface  1200 , such as described herein. The force input/haptic output interface includes an external cover  1202  that defines an input surface to receive user input and to provide haptic output. The external cover  1202  is positioned over and coupled to a frame  1204  via a compressible seal  1206 . As with other embodiments described herein, a touch input sensor  1208  is disposed below an interior surface of the external cover  1202 . In this example, a haptic actuator (described in greater detail below) is coupled below the frame  1204 . 
     In the illustrated embodiment, a force input sensor  1210  is disposed below the touch input sensor  1208  of the external cover  1202 , such that the force input sensor  1210  experiences strain in proportion to a magnitude of force applied to the external cover  1202 . 
     The force input sensor  1210  can be constructed in any number of suitable ways. For example, in one embodiment, the force input sensor  1210  is implemented as a piezoelectric sheet configured to compress or expand—and generate a charge measureable as a voltage spike—in response to a force applied to the external cover  1202 . In another embodiment, the force input sensor  1210  is implemented as a strain sensor. A strain sensor be formed from one or more traces of peizoresistive material. In another example, a strain sensor can be an inductive strain sensor configured to exhibit a change in inductance proportional to or otherwise related to a strain experienced by the external cover  1202  in response to a force applied to the external cover  1202 . 
     The force input sensor  1210  is offset from the frame  1204 , and thereby able to flex, by a separator  1212  (e.g., a spacer). The separator  1212  can be formed from any number of suitable elastic or otherwise flexible materials such as, but not limited to: silicone; plastic; glass; gel; a pressure-sensitive adhesive; and so on. In other cases, the separator  1212  may not be flexible and can be formed form a material such as metal or rigid plastic. In these examples, local or global flexibility of the frame  1204  and/or flexibility of the compressible seal  1206  may provide relief for the force input/haptic output interface  1200  in response to a force input from the user. 
     In this example, the frame includes a reduced-thickness section  1204   a . As with other embodiments described herein, the reduced-thickness section  1204   a  can at least partially defined a locally-flexible region of the frame  1204 . The force input/haptic output interface  1200  also includes a haptic actuator  1214  that is coupled to a reduced-thickness section  1204   a  of the frame  1204 . As with other embodiments described herein, the haptic actuator  1214  can include a piezoelectric element. 
     As a result of the constructed depicted in  FIG. 12 , high-voltage electronics that may be required to actuate the haptic actuator  1214  may be physically and structurally isolated from low-voltage electronics that may be required to operate the touch input sensor  1208  and/or the force input sensor  1210 . Further, in some examples, the frame  1204  may be formed from metal. In these examples, the frame  1204  may provide electromagnetic shielding between the haptic actuator  1214  and the force input sensor  1210  and/or the touch input sensor  1208 . As a result of these constructions, a total thickness of the force input/haptic output interface  1200  can be reduced. 
       FIG. 13  depicts a cross-section of another example force transducer coupled to a substrate associated with a force input/haptic output interface  1300 , such as described herein. The force input/haptic output interface  1300  is configured similar to other embodiments (e.g.,  FIG. 12 ) described herein. In this example, a force input sensor is coupled to a locally-flexible portion of a frame. The locally-flexible portion of the frame concentrates strain in the force input sensor, thereby increasing the sensitivity of that sensor. 
     In particular, the force input/haptic output interface  1300  includes an external cover  1302  positioned over a frame  1304  and a compressible seal  1306 . A touch input sensor  1308  is disposed below the external cover  1302 , and is separated from a locally-flexible portion  1312  the frame  1304  by a separator  1310 . A haptic actuator  1314  is coupled to a lower surface of the locally-flexible portion  1312 . The force input/haptic output interface  1300  also includes a force input sensor  1316  that is coupled to the locally-flexible portion  1312 . The force input sensor  1316  can be constructed in any number of suitable ways, such as those described in reference to  FIG. 12 . In this example, as with  FIG. 12 , electronics associated with the haptic actuator  1314  are physically and structurally isolated from those associated with the touch input sensor  1308 . 
     In yet another embodiment, a force input sensor and a haptic actuator can be laminated in a single stack below an input surface.  FIG. 14  depicts a force input/haptic output interface includes an external cover  1402  coupled to the frame  1404  via a compressible seal  1406 . A touch input sensor  1408  is coupled to an interior surface of the external cover  1402 . A force input sensor  1410  is disposed below the touch input sensor  1408  of the external cover  1402 . In this example, the force input sensor  1410  is backed by a stiffener  1412 . In typical embodiments the stiffener  1412  is formed from a rigid material such as metal, but this may not be required. In other examples, the stiffener  1412  is formed from plastic or glass. In some cases, the stiffener  1412  is formed from metal so as to electromagnetically shield the touch input sensor  1408 . 
     The force input/haptic output interface  1400  also includes a haptic actuator  1414  that is coupled to a lower side of the stiffener  1412 . The haptic actuator  1414  is separated from a reduced-thickness section  1404   a  of the frame  1404  by a gap  1416 . The gap  1416  permits the stack depicted in  FIG. 14  to deform toward the frame  1404  in response to a user input. As with other embodiments described herein, the haptic actuator  1414  can include a piezoelectric element. 
     Many examples provided above include haptic actuators configured to compress or expand in a direction parallel to a user input surface. However, this may not be required. For example,  FIG. 15  depicts a force input/haptic output interface  1500  that includes an external cover  1502  coupled to the frame  1504  via a compressible seal  1506 . As with other embodiments, a touch input sensor  1508  is coupled to an interior surface of the external cover  1502 . A force input sensor (not shown) can be disposed below the touch input sensor  1508  of the external cover  1502 , or in any suitable location. 
     The force input/haptic output interface  1500  also includes a haptic actuator  1510  that is coupled between the frame  1504  and the touch input sensor  1508 . As a result of this construction, expansion or compression of the haptic actuator  1510  perpendicular to the external cover  1502  results in outward or inward expansion of the external cover  1502 . As with other embodiments described herein, the haptic actuator  1510  can be any suitable haptic actuator such as a piezoelectric actuator, an electroactive polymer actuator, a linear actuator, and so on. 
     The foregoing embodiments depicted in  FIGS. 10-15  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 force input/haptic output interface 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, it may be understood that, generally and broadly, embodiments described herein can arrange various components of a force input/haptic output interface in any suitable order. For example, a force input sensor can be positioned: above, below, or adjacent to a touch input sensor; above, below, or adjacent to a haptic output element; above, below, or adjacent to a frame; above, below, or adjacent to a reduced-thickness section of a frame; above, below, or adjacent to a cover; and so on. Similarly, a haptic output element can be positioned: above, below, or adjacent to a touch input sensor; above, below, or adjacent to a force input sensor; above, below, or adjacent to a frame; above, below, or adjacent to a reduced-thickness section of a frame; above, below, or adjacent to a cover; and so on. Similarly, a force transducer configured to provide both haptic output and configured to receive force input from a user can be positioned: above, below, or adjacent to a touch input sensor; above, below, or adjacent to a frame; above, below, or adjacent to a reduced-thickness section of a frame; above, below, or adjacent to a cover; and so on. 
     Generally and broadly,  FIGS. 16-18  depict flow charts that correspond to various methods that may be associated with a force input/haptic output interface, such as described above. 
       FIG. 16  is a flow chart depicting example operations of a method of forming a haptic actuator, such as described herein. The method  1600  begins at operation  1602  in which a reduced-thickness section is formed in or through a substrate. The reduced-thickness section can be formed in any manner including, but not limited to: ablation; abrasion; etching; punching; cutting; and so on. In some cases, the reduced-thickness section can be formed and/or introduced into the substrate while forming the substrate (e.g., molding). In some cases, the reduced-thickness section can be formed by adding material to the substrate adjacent to the region. 
     The thickness of the substrate can be changed to any suitable thickness relative to adjacent portions of the substrate. In some cases, the reduced-thickness section is an opening. In other cases, the reduced-thickness section has a uniform thickness, whereas in others, the thickness of the reduced-thickness section varies. The reduced-thickness section can take any number of suitable shapes. 
     Next, at operation  1604 , a force transducer is coupled adjacent to the reduced-thickness section. In some cases, the force transducer is coupled directly to the reduced-thickness section. In other cases, the force transducer is coupled directly to the reduced thickness region. 
     Next, at operation  1606 , the force transducer can be coupled to drive circuitry and/or sense circuitry. In many cases, the drive circuitry and the sense circuitry are implemented as different portions of a single controller in electrical communication or otherwise coupled to the force transducer. 
       FIG. 17  is a flow chart depicting example operations of another method of forming a haptic actuator, such as described herein. The method  1700  beings at operation  1702  in which an instruction to provide haptic feedback is received. In typical embodiments, the instruction is received by a controller in signal communication with a set of force transducers or haptic actuators. 
     At operation  1704 , a set or subset of haptic actuators of a set of haptic actuators (or force transducers) is selected. In some cases, a single haptic actuator can be selected. In other cases, more than one haptic actuator can be selected. In still further embodiments, all haptic actuators of a set of haptic actuators can be selected. 
     At operation  1706 , the set or subset of haptic actuators of the set of haptic actuators selected at operation  1704  can be actuated or driven by a controller or drive circuitry. In some cases, a drive signal corresponding to each individual selected haptic actuator can be applied to the respective haptic actuator. In some cases, the drive signal(s) applied to each haptic actuator are the same, whereas in others the drive signal(s) may be unique to each haptic actuator of the set or subset of haptic actuators of the set of haptic actuators selected at operation  1704 . 
     In one embodiment, the drive signals are configured to generate haptic outputs that constructively interfere with one another at a particular location or selected location of an input or user interface surface associated with or coupled to the haptic actuators. In other cases, the drives signals are configured to generate haptic outputs that destructively interfere with one another at a particular location or more than one location of the input or user interface surface. In other cases, the drive signals are configured to vibrate a region of the input or user interface surface at a particular frequency. 
     It may be appreciated that the specific examples listed above are not exhaustive; any number of suitable drive signals can be applied to any number of haptic actuators. 
       FIG. 18  is a flow chart depicting example operations of a method of receiving force input. The method  1800  begins at operation  1802  in which an indication that a user is touching an input surface or user interface surface is received. Next, at operation  1804 , output from a force input sensor and/or a force transducer is received. Finally, at operation  1806 , the output can be correlated to a non-binary magnitude of force applied to the input surface or user interface surface. 
     As noted above, many embodiments described herein reference a force input/haptic output interface operated in conjunction with a non-display region of a portable electronic device, such as a trackpad of a laptop computer. It may be appreciated, however, that this is merely one example; other configurations, implementations, and constructions are contemplated in view of the various principles and methods of operation, and reasonable alternatives thereto, described in reference to the embodiments described above. 
     For example, without limitation, a force input/haptic output interface can be additionally or alternatively associated with: a display surface; an enclosure or enclosure surface; a planar surface; a curved surface; an electrically conductive surface; an electrically insulating surface; a rigid surface; a flexible surface; a key cap surface; a trackpad surface; a display surface; and so on. The user interface surface can be, without limitation: a front surface; a back surface; a sidewall surface; or any suitable surface of an electronic device or electronic device accessory. Typically, the user interface surface of a force input/haptic output interface is an external surface of the associated portable electronic device but this may not be required. 
     Further, although many embodiments reference a force input/haptic output interface positioned in a portable electronic device (such as a cell phone or tablet computer) it may be appreciated that a force input/haptic output interface can 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, 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. 
     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. 
     For example, as noted above a force transducer can be configured in a number of suitable ways. An example force transducer includes a ground electrode and a drive and/or sense electrode separated by a body formed from a material that is configured to contract or expand in the presence of an electric field and, additionally, develop a measureable charge in response to compression or strain. Suitable materials include, but may not be limited to: lead-based piezoelectric alloys; non-leaded materials such as metal niobates or barium titanate; in addition to electroactive polymers. In other examples, other piezoelectric compositions or multi-layered or interdigitated elements can be selected. 
     In many embodiments, a force transducer is communicably coupled to a controller that includes drive circuitry and/or sense circuitry. The drive circuit is configured to apply a drive signal to the drive and/or sense electrode of the force transducer. The drive signal can be any suitable signal including, but not limited to: a voltage bias; a voltage signal; an alternating signal; and so on. In some cases, the drive signal has an arbitrary waveform. The drive circuit can include one or more signal processing stages that may be used to generate, augment, or smooth the drive signal. For example, the drive circuit can include one or more of, without limitation and in no particular order: amplifying stages; filtering stage; multiplexing stages; digital-to-analog conversion stages; analog-to-digital conversion stages; comparison stages; feedback stages; and so on. The drive circuit can be implemented with analog circuit components, digital circuit components, passive circuit components, and/or active circuit components. In some examples, the drive circuit is implemented as an integrated circuit. 
     As with the drive circuit, the sense circuit, configured to receive voltage signals from the force transducer, can be implemented in any number of suitable ways. In many examples, the sense circuit includes one or more signal processing stages that may be used to receive, amplify, augment, or smooth a sense signal obtained from one or more of the sense electrodes. For example, the sense circuit can include one or more of, without limitation and in no particular order: amplifying stages; filtering stages; multiplexing stages; digital-to-analog conversion stages; analog-to-digital conversion stages; comparison stages; feedback stages; and so on. The sense circuit can be implemented with analog circuit components, digital circuit components, passive circuit components, and/or active circuit components. In some examples, the sense circuit is implemented as a single integrated circuit. 
     Once a sense signal (or more than one sense signal) is obtained, the sense circuit can correlate the one or more properties of the sense signal(s) to an amount of compression or strain experienced by the force transducer. In other cases, the sense circuit can correlate the measurement directly to an amount of force applied to the force transducer. 
     In many cases, drive circuitry and sense circuitry (or, more generally, a “controller”) can be configured to operate a haptic actuator and a force input sensor simultaneously. In these examples, sense circuitry can be configured to adjust an output received from a force input sensor bases on an operation of drive circuitry. For example, in one embodiment, a sense signal received by sense circuitry may have an increased amplitude due to a simultaneously or substantially simultaneous actuation of a haptic actuator. In this example, the sense circuitry can be configured to adjust and/or filter the sense signal based on the drive signal. In other cases, a sense signal received by sense circuitry may have a decreased amplitude due to a simultaneously or substantially simultaneous actuation of a haptic actuator. In this example, the sense circuitry can compensate for effects of the actuation by increasing the amplitude of the sense signal based on the drive signal. In still other cases, the sense signal and the drive signal may be out-of-band with respect to one another. For example, a drive signal may have a central frequency between 100 Hz and 250 Hz whereas a sense signal may have a central frequency between 0 Hz and 10 Hz. In these examples, the sense circuitry may be configured with a low-pass filter. 
     It may be appreciated that any implementation of any embodiment described herein can be configured in this manner. For example, with reference to the electronic device  100  depicted in  FIG. 1 , the set of force transducers of the force input/haptic output interface  110  can be used to user provide haptic output to a user and/or to receive force input from the user. For example, in a first mode (e.g., a “drive mode” or a “haptic mode”), the set of force transducers can be operated individually or collectively (e.g., constructively or destructively interfering at one or more locations) to produce a haptic output through the user interface surface. The haptic output can be any suitable output, such as a click, vibration, lateral shift, vertical shift, and so on. 
     In many cases, a haptic output is generated in conjunction with a function or operation of the electronic device  100 . For example, a user of the electronic device  100  can receive a first haptic output after selecting (e.g., with a cursor) a first element rendered in a graphical user interface displayed by the primary display  104 . The user can receive a second haptic output after selecting a second element rendered in the same graphical user interface. The first or second haptic outputs may be transient or sustained. 
     In some cases, one or more characteristics of a haptic output generated by the set of force transducers can depend upon a mode, state, application, function, setting, operation, or task of the electronic device  100 . A haptic characteristic can include, but may not be limited to: duration; intensity; amplitude; sound; location; type of displacement; frequency of vibration; amount of ring-down compensation; and so on. Any suitable haptic characteristic can be used. 
     In further cases, more than one haptic output can be generated by the set of force transducers at a particular time. For example, a first force transducer located at a first location of the user interface surface can generate a first haptic output while a second force transducer located at a second location of the user interface surface can generate a second haptic output. The different haptic outputs may be associated with different locations of the user interface surface. 
     In another example, in a second mode (e.g., a “sense mode” or an “input mode”), the set of force transducers can be operated individually or collectively to produce an electrical signal in response to a force input applied to the user interface surface. The electrical signal can be correlated (e.g., by a controller or circuitry in signal communication with the set of force transducers) to a magnitude and/or location of force applied by one or more objects in contact with the user interface surface. In some examples, the force input/haptic output interface  110  can be operated in the sense mode and the drive mode simultaneously. In other cases, the force input/haptic output interface  110  can alternatively operate in the drive mode and the sense mode. 
     Further to the foregoing, 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 is instead defined by the claims herein presented.

Metadata:
Filing Date: 20200810
Publication Date: 20221101
Grant Date: 20221101
Priority Date: 20170721
Inventors: LEHMANN, Alex J.
CAO, ROBERT Y.
MATHEW, DINESH C.
SILVANTO, MIKAEL M.
XU, QILIANG
WANG, PAUL X.
LOCKWOOD, ROBERT J.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/016", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0202", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01L1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01L1/142", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01L1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0202", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 72425865