PATENT DOCUMENT

Publication Number: US-11619976-B2
Application Number: US-202217876350-A
Country: US
Kind Code: B2

Title: Computer with keyboard

Abstract:
A device may include a display portion that includes a display housing and a display at least partially within the display housing. The device may also include a base portion pivotally coupled to the display portion and including a bottom case, a top case coupled to the bottom case and defining an array of raised key regions, and a sensing system below the top case and configured to detect an input applied to a raised key region of the array of raised key regions.

Claims:
What is claimed is: 
     
       1. A keyboard for a computing device, comprising:
 a bottom case; and 
 a glass top case coupled to a bottom case and defining:
 a top surface; 
 a bottom surface opposite the top surface; 
 a keyboard region along the top surface of the glass top case and defining a key region; and 
 a recess defined along the bottom surface of the glass top case and extending around the key region, wherein the key region is configured to locally deform in response to an input force. 
 
 
     
     
       2. The keyboard of  claim 1 , wherein the top surface of the glass top case is substantially planar. 
     
     
       3. The keyboard of  claim 1 , wherein the glass top case further defines a protrusion along the top surface of the glass top case and opposite the recess. 
     
     
       4. The keyboard of  claim 1 , wherein the recess is defined by a reduced thickness region of the glass top case. 
     
     
       5. The keyboard of  claim 1 , further comprising a sensing system positioned below the glass top case and configured to detect the local deformation of the key region in response to the input force. 
     
     
       6. The keyboard of  claim 5 , wherein the sensing system is further configured to detect a touch input applied to the key region. 
     
     
       7. The keyboard of  claim 6 , wherein:
 the keyboard further comprises a trackpad region positioned along a side of the keyboard region; and 
 the sensing system is further configured to detect gesture inputs applied to the trackpad region. 
 
     
     
       8. A laptop computer comprising:
 a housing; 
 a unitary glass top case coupled to the housing and defining:
 a trackpad region; 
 a keyboard region comprising a plurality of key regions; and 
 a channel formed into the unitary glass top case and extending around a key region of the plurality of key regions, the channel defining a local deformation region of the unitary glass top case in the key region, the local deformation region configured to deform in response to an input force applied to the key region; and 
 
 a sensing system below the unitary glass top case and configured to detect the deformation of the local deformation region in response to the input force. 
 
     
     
       9. The laptop computer of  claim 8 , wherein:
 the unitary glass top case has a first thickness in the key region; and 
 the unitary glass top case has a second thickness, less than the first thickness, in the channel. 
 
     
     
       10. The laptop computer of  claim 8 , wherein the channel is formed along a bottom surface of the unitary glass top case. 
     
     
       11. The laptop computer of  claim 8 , wherein:
 the key region is a first key region; 
 the local deformation region is a first local deformation region; 
 the channel is a first channel; and 
 the unitary glass top case further comprises:
 a second channel formed into the unitary glass top case and extending around a second key region of the plurality of key regions, the second channel defining a second local deformation region of the unitary glass top case in the second key region. 
 
 
     
     
       12. The laptop computer of  claim 8 , wherein the local deformation region is configured to deflect a greater distance than a region outside the local deformation region in response to the input force. 
     
     
       13. The laptop computer of  claim 8 , further comprising a display positioned below the unitary glass top case and configured to produce graphical outputs visible through the unitary glass top case. 
     
     
       14. The laptop computer of  claim 8 , wherein the sensing system comprises a piezoelectric material coupled to a bottom surface of the unitary glass top case in the key region. 
     
     
       15. A portable computing device comprising:
 a display portion comprising a display configured to produce a graphical output; and 
 a base portion coupled to the display portion and comprising:
 a base structure; 
 a transparent member coupled to the base structure and defining:
 a keyboard region; and 
 a set of recesses formed along a surface of the transparent member and defining a plurality of key regions within the keyboard region, wherein a key region of a plurality of key regions is configured to locally deform in response to an input force; and 
 
 a sensing system positioned below the transparent member and configured to detect the local deformation of the key region. 
 
 
     
     
       16. The portable computing device of  claim 15 , wherein the transparent member is formed of glass. 
     
     
       17. The portable computing device of  claim 15 , wherein the set of recesses is formed along a bottom surface of the transparent member. 
     
     
       18. The portable computing device of  claim 15 , wherein the set of recesses defines a continuous recess extending around a periphery of the key region. 
     
     
       19. The portable computing device of  claim 15 , further comprising a light source positioned below the transparent member and configured to illuminate a glyph within the key region. 
     
     
       20. The portable computing device of  claim 19 , further comprising an opaque mask positioned on a surface of the transparent member and defining the glyph.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/996,617, filed Aug. 18, 2020, which is a continuation of U.S. patent application Ser. No. 16/045,651, filed Jul. 25, 2018, now U.S. Pat. No. 10,775,850, which is a continuation of U.S. patent application Ser. No. 15/990,508, filed May 25, 2018, which is a nonprovisional patent application and claims the benefit of U.S. Provisional Patent Application No. 62/537,350, filed Jul. 26, 2017, the contents of which are incorporated herein by reference as if fully disclosed herein. 
    
    
     FIELD 
     The described embodiments relate generally to electronic devices, and more particularly to an electronic device having a keyboard with a flexible input surface. 
     BACKGROUND 
     Many electronic devices include keyboards to facilitate user input. Conventional keyboards include movable keys that are actuated by a user striking them with their fingers or another object. Some devices include touchscreens on which virtual keyboards may be displayed. Users may select individual keys of virtual keyboards by pressing on the part of the surface of the touchscreen that corresponds to a desired letter, character, or function. The surface of the touchscreen may be flat and featureless, and may thus occupy less space than a mechanical keyboard but may require users to identify the location of the keys by sight rather than by feel. 
     SUMMARY 
     A device may include a display portion that includes a display housing and a display at least partially within the display housing. The device may also include a base portion pivotally coupled to the display portion and including a bottom case, a glass top case coupled to the bottom case and defining an array of raised key regions, and a sensing system below the glass top case and configured to detect an input applied to a raised key region of the array of raised key regions. The array of raised key regions may form a keyboard of the device. The glass top case may further define a touch-input region along a side of the keyboard. The input may include a force applied to the raised key region of the array of raised key regions, and the raised key region may be configured to locally deflect in response to the applied force. The sensing system may be configured to detect the local deflection of the raised key region and detect touch inputs applied to the touch-input region. 
     The array of raised key regions may form a keyboard of the device, and the device may further include a support structure within the base portion, below the glass top case, and configured to resist deflection of the glass top case in a non-key region of the keyboard. 
     The raised key region may define a substantially planar top surface. The raised key region may be at least partially defined by a side wall that extends around the raised key region and is configured to deform in response to the input. 
     The device may further include a support structure positioned below a region of the glass top case that is between two adjacent raised key regions and the support structure may be configured to resist deflection of the region in response to a force applied to one of the two adjacent raised key regions. 
     The array of raised key regions may define a keyboard of the device and the glass top case may define a transparent portion along a side of the keyboard. The display may be a first display and the device may further include a second display positioned below the glass top case. The second display may be aligned with the transparent portion of the glass top case. 
     The glass top case may include a first glass layer defining the array of raised key regions and configured to deflect in response to a first force applied to the raised key region. The glass top case may also include a second glass layer below the first glass layer and configured to provide a buckling response in response to a second force, greater than the first force, applied to the raised key region. 
     A keyboard for an electronic device may include a bottom case, a glass top case coupled to the bottom case and defining an array of raised key regions, and a sensing system below the glass top case. A raised key region of the array of raised key regions may be configured to deflect in response to an actuation force applied to the raised key region, and the sensing system may be configured to detect the deflection of the raised key region. The raised key region may include a curved top surface. The raised key region may include a side wall extending from a base surface of the glass top case and supporting a top surface of the respective key region, and the side wall may be configured to deform in response to the actuation force. The keyboard may include a haptic actuator configured to impart a force to the raised key region in response to detection, by the sensing system, of the deflection of the raised key region. 
     The keyboard may further include a resilient member below the raised key region and configured to impart a returning force to the raised key region. The resilient member may provide a buckling response to the raised key region, and the buckling response may be provided in response to deflection of the raised key region beyond a threshold distance. The resilient member may be a collapsible dome. 
     A device may include a display portion comprising a display and a base portion hinged to the display portion. The base portion may include a bottom case and a glass top case coupled to the bottom case and defining an array of key regions, wherein a key region of the array of key regions is configured to produce a buckling response in response to an applied force. Each key region of the array of key regions may have a thickness that is less than about 40 μm. 
     The key region may define a top surface having a convex curved shape that is configured to collapse to provide the buckling response. The device may further include a spring below the key region and configured to impart a returning force to the key region. The device may further include a support structure supporting the glass top case relative to the bottom case and configured to prevent a force applied to the key region from buckling an additional key region that is adjacent the key region. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG.  1    depicts a simplified example of a computing device. 
         FIG.  2    depicts an exploded view of the computing device of  FIG.  1   . 
         FIG.  3    depicts an exploded view of a base portion of the computing device of  FIG.  1   . 
         FIGS.  4 A- 4 B  depict an example configuration of a glass top case. 
         FIG.  4 C  depicts an example force versus deflection curve of a key region of the glass top case of  FIGS.  4 A- 4 B . 
         FIGS.  5 A- 5 H  depict cross-sectional views of example glass top cases. 
         FIGS.  6 A- 6 B  depict another example configuration of a glass top case. 
         FIG.  6 C  depicts an example force versus deflection curve of a key region of the glass top case of  FIGS.  6 A- 6 B . 
         FIGS.  7 A- 7 F  depict cross-sectional views of other example glass top cases. 
         FIGS.  8 A- 8 D  depict example cross-sectional views of glass top cases with resilient members aligned with key regions. 
         FIG.  9 A  depicts another example configuration of a glass top case. 
         FIGS.  9 B- 9 E  depict example cross-sectional views of a glass top case that exhibits global buckling. 
         FIGS.  10 A- 10 C  depict example cross-sectional views of a dual-layer glass top case. 
         FIG.  10 D  depicts an example force versus deflection curve of a key region of the glass top case of  FIGS.  10 A- 10 C . 
         FIGS.  11 A- 11 B  depict an example glass top case with retractable key protrusions. 
         FIGS.  12 A- 14 B  depict example cross-sectional views of devices having actuators to produce retractable key protrusions. 
         FIGS.  15 A- 15 B  depict a glass top case with actuators that selectively form protruding key regions. 
         FIGS.  16 A- 16 B  depict example cross-sectional views of devices having support structures. 
         FIG.  17 A  depicts a detail view of the computing device of  FIG.  1   . 
         FIGS.  17 B- 17 D  depict example cross-sectional views of the glass top case of  FIG.  17 A . 
         FIG.  18 A  depicts a simplified example of a computing device. 
         FIGS.  18 B- 18 D  depict example cross-sectional views of the computing device of  FIG.  18 A . 
         FIG.  19    depicts a schematic diagram of an electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The embodiments described herein are generally directed to a keyboard that includes a glass member that defines an input surface of the keyboard. In particular, a user may touch or apply a force (e.g., push or strike) or otherwise contact the glass member directly to provide inputs to the keyboard. The glass member, also referred to as a glass cover, may be formed from a thin glass sheet that is flexible enough to deform locally in response to applications of force. For example, the glass sheet may be a strengthened glass having a thickness of about 40 microns or less. Due to the thinness and flexibility of the glass, when a typical typing force is applied to the thin glass sheet (e.g., via a finger), the glass may be primarily deformed directly under the force (e.g., under the finger) while other areas of the glass sheet remain substantially undeformed or less deformed. The local deformation of the thin glass may provide a more satisfying typing experience than thicker or less flexible glass, as the user may actually feel a deformation or depression that is similar to or suggestive of a conventional movable-key keyboard. Moreover, the local deformation may produce a softer typing feel (e.g., a less jarring impact) than striking a less compliant surface, such as a conventional touchscreen. 
     In some cases, the glass cover of a keyboard may include protrusions, contours, recesses, and/or other shapes or features that define distinct key regions of the keyboard. For example, the glass cover may be thermoformed or otherwise processed to form an array of raised key regions (e.g., protrusions, contoured key regions, etc.) that define the key regions of a keyboard. Raised key regions may provide a more familiar-feeling keyboard surface to users, as the individual key regions may have a similar shape and feel to conventional movable keys. Moreover, a user may be able to type faster and with fewer errors because they can feel the borders and boundaries of each key region and do not need to look at the keyboard to align their fingers with the keys. The ability to feel distinct key regions may also help prevent a user&#39;s hands from unintentionally drifting out of position during typing. 
     Further, due to the flexibility of the thin glass cover, the raised key regions may be configured to deform in response to typing inputs. Such deformations may provide a similar tactile feeling to conventional movable-key keyboards. Further, the raised key regions may be configured to provide various types of tactile responses. For example, the key regions may be configured to have a shape that buckles, provides a buckling response, or otherwise produces a perceptible tactile output (e.g., a click or snap) when pressed. As used herein, “buckling,” “buckling response,” and “buckling force” may refer to a force response of a key region or input region characterized by a gradual increase in an opposing force as a key region or input region is pressed, followed by a sudden or pronounced decrease in the opposing force. The decrease in the opposing force results in the familiar “click” feeling and, optionally, sound. An example force versus deflection curve illustrating a buckling response is described herein with respect to  FIG.  6 C . As another example, the key regions may be configured not to buckle or have a distinctive force peak, thus providing a more continuous force feedback during typing. 
     Other features and benefits are also made possible by a glass cover for a keyboard as described herein. For example, because the glass may be transparent, a display may be placed under the glass cover. The display may allow the keyboard, as well as any other region of the glass cover, to act as a display in addition to an input device. The display may allow the computer to display different keyboard layouts, keyboard alphabets, keyboard colors, or otherwise change the appearance of the keyboard by displaying different images through the transparent glass. Furthermore, the dielectric properties of glass may allow for the use of various touch and/or force sensors under the glass cover to detect touch and/or force inputs (or other types of user inputs) to key regions, as well as inputs applied to other, non-key regions of the glass cover (e.g., a touch-input region below a keyboard). As used herein, a non-key region may correspond to areas of a cover that are not configured as key regions of a keyboard, including, for example, the areas between key regions (which may resemble a key web), areas outside of a keyboard region, or the like. The glass sheet may also present a surface that may be free from openings, which may help protect internal components from contaminants and spills. 
       FIG.  1    depicts a computing device  100  (or simply “device  100 ”) that may include a glass cover, as described above. In particular, a base portion  104  of the device  100  may include a top case  112  (also referred to as a cover) that is formed at least partially from glass and that defines a keyboard and optionally other input regions (e.g., a trackpad or touch-input region) of the device  100 . 
     The device  100  resembles a laptop computer that has a display portion  102  and a base portion  104  flexibly or pivotally coupled to the display portion  102 . The display portion  102  includes a display housing  107  and a display  101  at least partially within the display housing  107 . The display  101  provides a primary means of conveying visual information to the user, such as by displaying graphical user interfaces. The base portion  104  is configured to receive various types of user inputs (also referred to herein as inputs), such as touch inputs (e.g., gestures, multi-touch inputs, swipes, taps, etc.), force inputs (e.g., presses or other inputs that satisfy a force or deflection threshold), touch inputs combined with force inputs, and the like. Touch and/or force inputs may correspond to a user striking a key region or other input surface, similar to a conventional typing motion or action. 
     The base portion  104  may also provide outputs for conveying information to a user, such as with indicator lights, haptic output devices, displays mounted in the base portion  104 , or the like. In some cases, providing various types of input and output via the base portion  104  is facilitated or enabled by using a glass top case  112  on the base portion  104 , as described herein. 
     The display portion  102  and the base portion  104  may be coupled to one another such that they can be positioned in an open position and a closed position. In the open position, a user may be able to provide inputs to the device  100  via the base portion  104  while simultaneously viewing information on the display portion  102 . In the closed position, the display portion  102  and the base portion  104  are collapsed against one another. More particularly, the display portion  102  and the base portion  104  may be hinged together (e.g., via a pivot or hinge mechanism  103 ) to form a clamshell device that can be moved between an open and a closed configuration. 
     As noted above, the base portion  104  may include a top case  112  coupled to a bottom case  110 . The bottom case  110  may be formed from any suitable material, such as metal (e.g., magnesium, aluminum, titanium, etc.), plastic, glass or the like, and may define, along with the top case  112 , a portion of an interior volume of the base portion  104 . The top case  112  may be attached to the bottom case  110  in any suitable way, including adhesives, mechanical interlocks, joining members, fusion bonds, or the like. 
     The top case  112  may be formed at least partially, and in some cases entirely, from glass. The glass top case  112  may be configured to deflect or deform locally in response to input forces applied thereto. For example, the glass of the top case may be sufficiently thin and be formed into a shape that allows the top case to form depressions or otherwise deflect when a user presses on the glass. Thicker or more rigid glass, by contrast, may not deflect significantly in response to typical input forces applied by a user&#39;s fingers. Such unyielding glass surfaces may not produce a desirable tactile feel for typing inputs, and may not deflect enough to facilitate force sensing (such as where force is detected based on the amount of deflection of the glass). Accordingly, a thin glass top case, as described herein, can deflect locally, thereby providing both a desired tactile response (e.g., a feel that is similar to or suggestive of a movable-key keyboard) and the ability to detect touch inputs using mechanical means, such as domes, deflection sensors, and the like. 
     The top case  112  may be formed from one or more layers of strengthened glass (e.g., chemically strengthened, ion-exchanged, heat-treated, tempered, annealed, or the like). The glass may be thinner than about 100 μm, thinner than about 40 μm, or thinner than about 30 μm. The glass top case  112  may be configured to locally deflect or deform any suitable amount in response to a typing force. For example, the glass top case  112  may be configured to locally deflect about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, or any other suitable amount, in response to a sample typing force (e.g., 100 g, 250 g, 500 g, 1 kg, etc.). 
     The top case  112  may define or include input regions such as a keyboard region  114  and a touch-input region  116 . The keyboard region  114  may include or define key regions  115 , which may correspond to keys of a keyboard or other input regions. The top case  112 , and in particular the keyboard region  114 , may lack raised or otherwise protruding key regions (e.g., it may be smooth and/or substantially planar). In such cases, key regions  115  may be differentiated using ink, paint, dyes, textures, displays, or any other suitable technique. In other cases, the keyboard region  114  of the top case  112  may be shaped to define physically distinctive key regions  115 . For example, as described herein, the top case  112  may include recesses, protrusions, borders, or other physical features on its exterior surface that define and/or delineate distinct key regions  115  and that can be felt by a user when typing on or otherwise touching the keyboard region  114 . The top case  112  may instead or in addition include channels or grooves on its interior surface that correspond to distinct key regions. Such interior and exterior features may isolate or localize deformations caused by forces (e.g., typing forces) applied to the key regions  115 . For example, a deformation of the top case  112  due to a force applied to a protrusion, which may resemble a keycap of a conventional keyboard, may be substantially isolated to that protrusion, thus providing a sensation to the user of pressing a conventional mechanical keyboard key. 
     In some cases, the entire top surface of the top case  112  may be touch and/or force sensitive, and may allow detection of touch inputs substantially anywhere along its top surface, including in a keyboard region as well as surrounding regions (e.g., the touch-input region  116 ). In addition to receiving or detecting inputs, the top case  112  may be configured to provide haptic, tactile, visual, auditory, or otherwise perceptible outputs to a user. For example, the top case  112  may include or be integrated with displays, light sources, haptic actuators, or the like, that provide outputs that are detectable via the top case  112 . The composition and configuration of the top case  112  may facilitate and integrate these (and other) input and output functions. For example, a continuous, nonconductive top case  112  formed from a thin, deformable glass may allow inputs to be detected through the top case  112  while also providing tactile feedback in the form of key regions  115  that buckle, deflect, deform, or otherwise move in response to applied forces. 
     The top case  112  may define a continuous, unbroken top surface of the base portion  104 . For example, the top case  112  may have no seams, openings, through-holes, or other discontinuities in the portion of the top case  112  that forms an exterior surface of the base portion  104 . The top case  112  may extend to the outer edges of the base portion  104 . Accordingly, the top case  112  may prevent or reduce the possibility of liquid, dust, dirt, or other contaminants or debris from entering the base portion  104  through the top surface of the top case  112 . 
     The touch-input region  116  may be configured to detect touch- and/or force-based inputs, and may be or may include any portion of the top case  112 , including substantially the entire top case  112  including the keyboard region  114 , the touch-input region  116 , or any other portion of the top case  112 . In some cases, substantially the entire top case  112 , from edge to edge, may define a touch-sensitive surface. In this way, touch or trackpad inputs, such as clicks, taps, gestures (e.g., swiping, pinching), and multi-touch inputs, may be detected on any portion of the top case  112 , including on individual key regions  115  within the keyboard region  114  as well as on portions of the top case  112  outside of the keyboard region  114 . 
       FIG.  2    is a partial exploded view of the device  100 . As described above, the device  100  includes a top case  112  that forms part of the base portion  104  and defines an array of key regions  115  (e.g., raised or otherwise physically or visually differentiated key regions, as described herein). As shown in  FIG.  2   , the base portion  104  is pivotally coupled to a display portion  102  via hinges  103  (or any other suitable mechanism) to form a foldable or clamshell type laptop or notebook computer. 
     The base portion  104  may include the bottom case  110  and the top case  112 , described above, which together define an interior volume of the base portion  104 . The base portion  104  may also include components  208  within the interior volume, such as processors, memory devices, batteries, circuit boards, input/output devices, haptic actuators, wired and/or wireless communication devices, communication ports, disk drives, and the like. As described above, the top case  112  may be a continuous surface (e.g., having no holes or openings in its top surface) to prevent or limit ingress of liquid, debris, or other contaminants into the interior volume, thereby reducing the chance of damage to the components  208 . Examples of components that may be included in the components  208  are discussed herein with reference to  FIG.  19   . 
       FIG.  3    depicts an exploded view of the base portion  104 . The base portion  104  includes the top case  112 , the bottom case  110 , and a touch and/or force sensing system  302  below the top case  112  (e.g., disposed within the interior volume defined by the top case  112  and the bottom case  110 ). The touch and/or force sensing system  302  may provide touch and/or force sensing functionality to detect touch inputs and/or force inputs (and/or other types of user inputs) applied to the top case  112 . For example, the touch sensing functions of the touch and/or force sensing system  302  may detect the presence and position of a touch input applied to the top case  112  (such as on the keyboard region  114 ), while the force sensing functions of may detect a magnitude (and optionally location) of a force input that results in a deformation of the top case  112 . 
     The touch and/or force sensing system  302  may include any suitable components and may rely on any suitable force and/or touch sensing technologies, including capacitive, resistive, inductive, or optical sensing, electromechanical switches, collapsible domes, or any other suitable technology. Moreover, the touch and/or force sensing system  302 , as depicted in  FIG.  3   , generically represents the one or more components that provide the touch and/or force sensing systems. While the touch and/or force sensing system  302  is depicted as a single block or component, in many implementations, the touch and/or force sensing system  302  would be formed from multiple components and/or layers. Thus, the touch and/or force sensing system  302  need not be configured as a sheet as shown in  FIG.  3   , but may take any physical form and may be integrated with the base portion  104  in any suitable way. For example, the touch and/or force sensing system  302  may be or may include an array of collapsible domes or switches, or an array of electroactive polymer switches, or the like. As another example, the touch and/or force sensing system  302  may include multiple sensors for detecting touch inputs (e.g., each sensor associated with a different region of a top case), as well as multiple sensors for detecting force inputs. Further, touch and force sensing functions may be provided by separate components or systems, or integrated into a single component or system. 
     The base portion  104  may also include an optional display  304  below the touch and/or force sensing system  302 . The display  304  may be used to produce images on different regions of the top case  112 , such as the keyboard region  114 , a touch-input region  116 , or the like. For example, the display  304  may produce images of characters, glyphs, symbols, keycaps, or other images that are visible through the top case  112  and that are optionally aligned with individual key regions  115 . Because the display  304  can dynamically change what is displayed, different images may be displayed at different times, allowing the device  100  to display different keyboard layouts, different key glyphs, and the like. Where the base portion  104  includes the display  304 , portions of the touch and/or force sensing system  302  and the top case  112  may be transparent or substantially transparent, and aligned with the display  304  or an active portion of the display  304 , to allow the display  304  to be visible to a user through the top case  112 . 
       FIGS.  4 A- 4 C  relate to an example configuration of a glass top case  400  (which may correspond to the top case  112 ,  FIG.  1   , and which may be referred to simply as a top case  400 ) in which the glass is configured to deform in response to an actuation force applied to a key region (e.g., a protrusion  402 ) without producing a click or a “buckling” style tactile response. As described above, the top case  400  may be formed from a chemically strengthened glass having a thickness that facilitates localized deformation in response to actuation forces (e.g., finger presses on key regions). For example, the top case  400  may be formed from one or more layers of strengthened glass (e.g., chemically strengthened, ion-exchanged, heat treated, tempered, annealed, or the like), and may be thinner than about 100 μm, thinner than about 40 μm, or thinner than about 30 μm. 
       FIG.  4 A  is a partial cross-sectional view of a top case  400 , corresponding to a view of a top case along line A-A in  FIG.  1   , showing an example in which key regions (e.g., key regions  115 ) are defined by protrusions  402  formed in the top case  400 . The protrusions  402  may extend or otherwise protrude above a portion of the top case  400  that is adjacent the key regions. 
     The protrusions  402  protrude above a base level  403  of the top case  400  by a height  407 . The height  407  may be about 0.5 mm, 0.2 mm, 0.1 mm, or any other suitable height. The protrusions  402  may include an edge  404  defining an outer perimeter of top surfaces  405  of the protrusions  402 . The protrusions  402  may also include side walls (e.g., corresponding to item  410 ) that extend from a base level  403  (e.g., a surface of the top case  400  other than a protrusion  402 ) of the top case  400  to the top surfaces  405  of the protrusions  402 . The side walls may support the top surface  405  of the protrusions  402 . The side walls may be continuous side walls that extend around the periphery of the top surfaces  405 . The side walls may provide structural rigidity for the key region. In some cases, as described herein, the side walls may buckle, flex, or otherwise deform to provide typing compliance and/or tactile feedback. For example, in some configurations, the side walls of a protrusion  402  may deform (e.g., to provide typing compliance and/or tactile feedback) while the top surface  405  of the protrusion  402  may remain substantially undeformed (or otherwise contribute less to the deflection of the protrusion  402  than the side walls). In such cases, the top surfaces  405  may be less flexible or deformable (e.g., stiffer) than the side walls. 
     As noted above, the protrusions  402  may provide useful tactile information to a user of the keyboard, as the individual key regions can be distinguished by touch, allowing the user to accurately and consistently locate their fingers on the key regions by feeling the edges or corners  404  of the protrusions  402 . 
     The top case  400  may be processed in any suitable way to form the protrusions  402 . For example, the top case  400  may be thermoformed, molded, machined, or otherwise processed to produce the desired shape. In some cases, the top case  400  has a substantially uniform thickness over at least a keyboard region of the top case  400  (e.g., the keyboard region  114 ,  FIG.  1   ), and in some cases over the entire top case  400 . For example, the thickness of the top case  400  at the base level (dimension  408 ), a side of a protrusion  402  (dimension  410 ), and a top portion of the protrusion  402  (dimension  412 ) may be substantially the same. In other cases, the top case  400  may have different thicknesses at different locations on the top case  400 , such as a first thickness for dimension  412  and a different thickness for dimension  410 . For example, the thickness of the side of a protrusion (dimension  410 ) may be less than that of the top portion (dimension  412 ) so that the side of the protrusion deforms more than the top portion of the protrusion in response to a force applied to the top surface  405 . 
       FIG.  4 B  is another partial cross-sectional view of the top case  400 , showing how the top case  400 , and in particular a protrusion  402 , may deform in response to a force applied on the top surface  405 . In particular,  FIG.  4 B  shows a finger  406  pressing on and deforming the protrusion  402 , which may correspond to a typing input. The protrusion  402  may deform, as shown, while other portions of the top case  400  remain substantially undeformed or undeflected. In some cases, large-scale deflections of the whole top case  400  are resisted, limited or prevented by support structures that brace or otherwise support the top case  400  relative to another part of the device in which it is integrated (e.g., the bottom case  110 ). The shape of the deformed protrusion  402  shown in  FIG.  4 B  is merely exemplary, and the protrusion  402  may have a shape or profile different that than shown when the protrusion  402  is deformed. 
     As noted above, the top case  400  may be configured to deform without producing a buckling or collapsing output.  FIG.  4 C  shows a force versus deflection (e.g., travel) curve  414  characterizing the force response of the protrusion  402  as it is deformed. In particular, as an actuation force (e.g., from the finger  406 ) causes the protrusion  402  to deform downwards, the force response of the protrusion  402  increases along a path from point  416  to point  418 . As shown, the path is increasing (e.g., has a positive slope) along the travel without a sudden or pronounced decrease in force, and thus does not collapse or produce a buckling response (e.g., a “click”). In some cases, as described herein, haptic actuators or other components may be used with top cases that have non-buckling configurations to produce tactile responses that simulate a buckling response or otherwise indicate that an input has been detected and registered by the keyboard. 
     While  FIGS.  4 A- 4 B  show one example configuration of a top case with non-buckling key regions, other top cases with non-buckling key regions may have different configurations, protrusion shapes, recesses, or other features.  FIGS.  5 A- 5 H  show a variety of such examples. In the examples shown in  FIGS.  5 A- 5 H , where the key regions are defined by or include ridges or side walls, the side walls may be configured so that they do not collapse or buckle in response to normal typing forces. In some cases, the side walls or ridges that define the key regions may have a greater stiffness than the top surfaces. The higher stiffness of the side walls may help isolate and/or localize deflections to a top surface. In some cases, the side walls or ridges may be less stiff than the top surface, which may result in deformation being substantially isolated to the side walls. This may result in the top surface deflecting in a more uniform manner (e.g., it may not substantially curve or bend). In yet other cases, the side walls or ridges are not appreciably stiffer than the top surface, and the deflection of the key region may include deflection of both the top surface and the side walls. In any of these embodiments, as noted above, the deflection of the top surface and/or the side walls may not produce a buckling response or other abrupt reduction in force response. 
     Except where specifically noted, all of the example top cases shown in  FIGS.  5 A- 5 H  may be formed of glass and may have a substantially uniform thickness (e.g., less than about 100 μm, 40 μm, 30 μm, or any other suitable dimension). The glass may be any suitable glass, such as strengthened glass (e.g., chemically strengthened, ion-exchanged, heat treated, tempered, annealed, or the like). 
       FIG.  5 A  shows a partial cross-sectional view of a top case  500  (which may correspond to the top case  112 ,  FIG.  1   ) that defines protrusions  502 . The protrusions  502  are similar to the protrusions  402  in  FIGS.  4 A- 4 B , but have edges  504  that have a greater radius of curvature between the side wall and the top surface than the edges  404  in  FIGS.  4 A- 4 B . The rounded edges  504  may produce a different feel to the user, and may have greater resistance to chipping, breaking, cracking, or other damage. In some cases, the radius of the rounded edges  504  may be about 10 μm, 5 μm, or any other suitable dimension that produces a noticeably rounded edge (e.g., not a sharp, discontinuous corner). The protrusions  502  of the top case  500  may protrude above a base level of the top case  500  by a height  506 . The height  506  may be about 0.5 mm, 0.2 mm, 0.1 mm, or any other suitable height. 
       FIG.  5 B  shows a partial cross-sectional view of a top case  510  (which may correspond to the top case  112 ,  FIG.  1   ) that defines protrusions  512 . The protrusions  512  are similar to the protrusions  402  in  FIGS.  4 A- 4 B , but have concave top surfaces  513  instead of the substantially planar top surfaces  405 . The concave top surfaces  513  may provide comfortable surfaces that generally match the shape of a user&#39;s fingertip. The concave top surfaces  513  may have a substantially cylindrical profile, a substantially spherical profile, or any other suitable shape. The protrusions  512  of the top case  510  may protrude above a base level of the top case  510  by a height  516 . The height  516  may be about 0.5 mm, 0.2 mm, 0.1 mm, or any other suitable height. While  FIG.  5 B  shows concave top surfaces  513 , in other implementations the top surfaces may be convex. 
       FIG.  5 C  shows a partial cross-sectional view of a top case  520  (which may correspond to the top case  112 ,  FIG.  1   ) that defines protrusions  524  that extend around and define key regions  522 . Whereas the protrusions in the top cases  400 ,  500 ,  510  defined key regions that were raised relative to a surrounding or adjacent portion of the top case, the protrusions  524  of the top case  520  extend around a surface that is substantially flush or even with nearby portions of the top case (e.g., the area of the top case  520  between the key regions  522 . This may provide a shorter stack height for the top case  520 , and thus a shorter height of the device in which it is incorporated. 
     Because the protrusions  524  define and/or extend around the key regions  522 , users may be able to differentiate the key regions  522  by touch, allowing faster typing, easier finger alignment, and the like. The protrusions  524  may be any height  526  above a base level of the top case  520  (e.g., the top surfaces of the key regions  522  or the regions that are between the protrusions  524  and extend around the key regions  522 ), such as about 0.5 mm, 0.2 mm, 0.1 mm, 0.05 mm, or any other suitable height. The recesses  528  may be an artifact of a process used to form the top case  520 , such as thermoforming or molding a glass sheet of a uniform thickness, or they may be machined into the bottom surface of the top case  520 . 
     As shown, the top case  520  may have complementary recesses  528  below the protrusions  524 , and the top case  520  may have a substantially uniform thickness, as described above. The curved portions of the top case  520  that define the protrusions  524  and complementary recesses  528  may serve as flexible joints that facilitate deflection of the key regions  522  relative to a remainder of the top case  520 . In some cases, the portions of the top case  520  defining the protrusions  524  and recesses  528  are thinner than surrounding areas, which may produce more top case deformation in response to a given force. 
     In other cases, the top case  520  may include the protrusions  524  but maintain a substantially planar bottom layer (e.g., omitting the recesses  528 ). This configuration may stiffen the glass around the key regions  522 , which may aid in isolating and localizing deflection of the key regions  522  in response to applications of force. 
       FIG.  5 D  shows a partial cross-sectional view of a top case  530  (which may correspond to the top case  112 ,  FIG.  1   ) with key regions  532  defined by a protruding portion  533  and a recessed portion  534 . The recessed portions  534  may extend around the protruding portions  533 , and may serve as flexible joints that facilitate deflection of the key regions  532  relative to a remainder of the top case  530 . The recessed portions  534  may also serve to visually and tactilely distinguish the key regions  532  from one another. The protruding portions  533  may be any height  536  above a base level of the top case  530 , such as about 0.5 mm, 0.2 mm, 0.1 mm, 0.05 mm, or any other suitable height. Also, the top case  530  may have a substantially uniform thickness, or it may have different thicknesses at different locations. For example, the glass forming the recessed portions  534  and the sides of the protruding portions  533  may be thinner than or thicker than the glass between the key regions  532 . 
       FIG.  5 E  shows a partial cross-sectional view of a top case  540  (which may correspond to the top case  112 ,  FIG.  1   ) with key regions  542  that are defined, on a bottom surface of the top case  540 , by recesses  544 . The top surface of the top case  540  may be substantially planar or featureless. The recesses  544  may visually define the key regions  542  on the top case  540 . In particular, if the top case  540  is transparent or translucent glass, the recesses  544  may be visible through the glass material. The recesses  544  may also define areas of thinner glass, which may increase the amount of deformation of the top case  540  in response to forces applied to the key regions  542  as compared to a top case having a uniform thickness. Moreover, the recesses  544  may aid in isolating and localizing deflection of the key regions  542  in response to forces applied to the key regions  542 . 
       FIG.  5 F  shows a partial cross-sectional view of a top case  550  (which may correspond to the top case  112 ,  FIG.  1   ) with key regions  552  that are defined by protrusions formed by attaching pads  554  to a substrate  553 . The substrate  553  may be formed from glass (such as a strengthened glass) and may have a thickness that promotes localized deformation of the substrate  553  in response to applied forces (e.g., less than about 40 μm). The pads  554  may protrude above a top surface of the substrate  553  by a height  556  (e.g., about 0.5 mm, 0.2 mm, 0.1 mm, or any other suitable height). 
     The pads  554  may be any suitable material, such as glass, metal, plastic, ceramic, sapphire, or the like, and may be attached to the substrate  553  using adhesive, fusion bonding, intermolecular forces (e.g., hydrogen bonds, Van der Waals forces, etc.), or any other suitable technique. As shown, the pads  554  are a single component. In other cases, they may comprise multiple components or members, such as multiple layers of the same or different materials. The pads  554  may be transparent or opaque, and may have the same or a contrasting appearance (e.g., color, texture, material, opacity, etc.) as the substrate  553 . In some cases, the pads  554  and the substrate  553  may be a monolithic component (e.g., formed from a single, continuous sheet of glass). 
     The pads  554  may provide several functions. For example, they may visually and tactilely differentiate different key regions  552 , as described herein. In some cases, glyphs or other indicium may be formed on the top of the substrate  553  or the bottom of the pads  554  (or otherwise positioned between the substrate  553  and the pads  554 ), which may be visible through the pads  554 . Further, the pads  554  may increase the stiffness or resistance to deformation of the substrate  553  in the key regions  552 . This may help provide a more uniform or flat deflection of the key regions  552  in response to force applications. For example, instead of forming a curved divot in the substrate  553 , the pads  554  may cause a deformation with a more planar shape due to the resulting increased stiffness in the key regions  552 . 
       FIG.  5 G  shows a partial cross-sectional view of a top case  560  (which may correspond to the top case  112 ,  FIG.  1   ) with key regions  562  that are defined by pads  564  coupled to a bottom surface of a substrate  563 . The pads  564  and the substrate  563  may be substantially similar to the pads  554  and substrate  553  described with respect to  FIG.  5 F , and may have similar materials, dimensions, and functions. For example, the pads  564  may increase the stiffness or resistance to deformation of the substrate  563  in the key regions  562 . Also, in cases where the substrate  563  is transparent, the pads  564  may be visible through the substrate  563  to visually distinguish the key regions  562 . 
       FIG.  5 H  shows a partial cross-sectional view of a top case  570  (which may correspond to the top case  112 ,  FIG.  1   ) with key regions  572  defined by protrusions  571  formed in a substrate  573 . The top case  570  also includes pads  574  positioned on a bottom surface of the protrusions  571  and aligned with an input surface of the protrusions  571 . The substrate  573  may be substantially similar to the top case  500  described above with respect to  FIG.  5 A , and may have similar materials, dimensions, and functions. The pads  574  may be substantially similar to the pads  554  and  564  ( FIGS.  5 F,  5 G ), and may likewise have similar materials, dimensions, and functions. For example, the pads  574  may be formed from or include glass and may be bonded to the glass substrate  573 . The pads  574  may locally stiffen the substrate  573  to increase the uniformity of the deformation of the substrate  573  in response to applications of force, and may also direct or isolate deformations to certain areas of the substrate  573 , such as the sides  576  of the protrusions  571 . 
     As noted above, the foregoing example top case configurations may be configured to have non-buckling key regions. Due to the thinness and relative deformability of the glass used for the top case, however, glass top cases as described herein may be configured to have key regions that buckle, collapse, or otherwise produce a tactile “click” when pressed.  FIGS.  6 A- 7 F  illustrate example top case configurations that have buckling key regions. 
       FIG.  6 A  is a partial cross-sectional view of a top case  600 , corresponding to a view of a top case along section A-A in  FIG.  1   , showing an example in which key regions (e.g., key regions  115 ,  FIG.  1   ) are defined by convex or dome-shaped protrusions  602  formed in the top case  600 . As described with respect to  FIG.  6 C , these key regions (as well as those shown in  FIGS.  7 A- 7 F ) may be configured to produce a buckling response. 
     The dome-shaped protrusions  602  protrude above a base level  603  of the top case  600  by a height  604 . The height  604  may be about 0.5 mm, 0.2 mm, 0.1 mm, or any other suitable height. As noted above, the protrusions  602  may provide useful tactile information to a user of the keyboard, as the individual key regions can be distinguished by touch, allowing the user to accurately and consistently locate their fingers on the key regions by feeling the protrusions  602 . 
       FIG.  6 B  is another partial cross-sectional view of a top case  600 , showing how the top case  600 , and in particular a protrusion  602 , may deform in response to a force applied thereto. In particular,  FIG.  6 B  shows a finger  606  pressing on and deforming the protrusion  602 , which may correspond to a typing input. The protrusion  602  may deform, as shown, while other portions of the top case  600  remain substantially undeformed or undeflected. 
       FIG.  6 C  shows a force versus deflection (e.g., travel) curve  608  characterizing the force response of the protrusion  602  as it is deformed. In particular, as an actuation force (e.g., from the finger  606 ) causes the protrusion  602  to deform downwards, the force response of the protrusion  602  increases along a path from point  610  until an inflection point  612  is reached. When the inflection point  612  is reached, the protrusion  602  collapses or buckles and the force response of the protrusion abruptly decreases along a path from point  612  to point  614 . The inflection point  612  may define or correspond to a deflection threshold of the protrusion. For example, once the deflection of the key region reaches or passes beyond a threshold distance (e.g., corresponding to the inflection point  612 ), the protrusion  602  buckles and provides a buckling response to the key region. 
     After point  614 , the force response begins to increase again (e.g., once the protrusion  602  is inverted and the glass ceases to deform as easily). This force response may produce a sudden or pronounced decrease in force that resembles the click of a mechanical keyboard, and thus may produce a typing experience that is similar to or suggestive of using a movable-key keyboard, despite the unitary structure of the glass top case. 
     Under normal operating conditions and forces, a device may detect an input (e.g., register that a key has been pressed) at point  612 , where the force begins to drop off, or at point  614 , where the force begins to increase again. As described herein, any suitable sensor or sensing system may be used to detect deformations of a top case and determine when to register an input, including touch sensors, force sensors, optical sensors, and the like. 
       FIGS.  7 A- 7 F  show additional examples of top case shapes that may produce buckling-style tactile outputs, as well as example geometries of the top cases when deflected past an inflection point as described with respect to  FIG.  6 C . In particular,  FIGS.  7 A- 7 B  show partial cross-sectional views of a top case  700  that includes protrusions  702  similar to those of the top case  500  ( FIG.  5 A ). The protrusions  702  may be configured so that they invert and buckle when deformed. This may be achieved by selecting different dimensions for the protrusions  702  as compared to those shown in  FIG.  5 A , such as a greater height, more gently curved protrusion side walls, thinner side walls, a smaller top surface (e.g., in a horizontal direction, as shown), or the like. 
       FIGS.  7 C- 7 D  show partial cross-sectional views of a top case  720  that resembles the top case  510  ( FIG.  5 B ), but has been configured to have a buckling mode. For example, the protrusions may be differently sized, and/or the sides  722  of the protrusions may have different dimensions and/or material properties (e.g., different thicknesses, different heights, different radii of curvature, different stiffness) that produce a buckling deformation when pressed, as shown in  FIG.  7 D . 
       FIGS.  7 E- 7 F  show partial cross-sectional views of a top case  730  that includes protrusions  734  with pads  732  on a top surface of the protrusions  734 . The pads  732  may be similar to the pads  564  and  574  described herein, and may be formed from the same materials, be coupled to a substrate  736 , and provide the same functions of the pads  564  and  574 . In some cases, the stiffening function of the pads  732  causes the underlying substrate  736  to produce a different deflection mode than would be produced without the pads  732 . For example, the increased stiffness of the protrusions  734  where the pads  732  are attached may cause deformations to be isolated to the side walls of the protrusions  734 , which may result in a buckling type of deformation and force response (as shown in  FIG.  7 F ), rather than a linear or continuous force response (e.g., as shown in  FIGS.  4 A- 4 C ). 
     In some cases, resilient members may be incorporated into a device using a deformable glass top case in order to increase or change the force response of the key regions of the top case. For example, springs, domes, elastomeric materials, or the like, may be provided below the top case. Such resilient members may provide a returning force to protrusions formed in the top case. For example, where the protrusions of a top case are configured to invert (e.g., collapse or buckle), the protrusions may not return to their original, protruding orientation without a returning force. Accordingly, resilient members may bias the protrusions towards an undeflected or undeformed position to ready the protrusion to receive another input. In examples where the top case is not configured to collapse or buckle, resilient members may be used to change the force response, for example, to increase the amount of force it takes to deform the top case a certain amount, or to change a spring rate or other property of the force response of the top case. 
       FIGS.  8 A- 8 C  show partial cross-sectional views of an example top case  800  having various types of resilient members interacting with protrusions in the top case to, for example, impart a returning force on the protrusions. Resilient members may be configured to deform or compress when a force is applied and return to an original state or shape when the force is removed. Examples of resilient members are described herein. The protrusions  802  in the top case  800  may be configured to buckle or collapse, as described with respect to  FIGS.  6 A- 6 C , or deform without buckling or collapsing, as described with respect to  FIGS.  4 A- 4 C . 
     For example,  FIG.  8 A  shows a top case  800  with coil springs  804  aligned with protrusions  802 . The coil springs  804  may be supported by a lower member  806 , which may correspond to a bottom case of an enclosure (e.g., the bottom case  110 ,  FIG.  1   ), or any other component or structure of an electronic device. The coil springs  804  may be metal, rubber, plastic, or any other suitable material, and may have any suitable spring rate, including linear spring rates, nonlinear spring rates, and the like. As noted, the coil springs  804  may provide a returning force to the protrusions  802 . 
       FIG.  8 B  shows the top case  800  with domes  808  aligned with the protrusions  802 . The domes  808  may be collapsible domes (e.g., domes that follow a force versus deflection curve similar to that shown in  FIG.  6 C ), or they may be spring domes that do not collapse or otherwise produce a tactile “click.” In cases where the top case  800  does not provide a buckling force response (e.g., as described with respect to  FIGS.  6 A- 6 C ), collapsible domes may be used to produce a tactile “click” despite the top case itself not providing a buckling-style force response. This may permit the use of different shapes for the key regions (e.g., protrusions, recesses, featureless layers, etc.), which may not be sufficient alone to produce a tactile click, while still providing the tactile feel of a collapsing dome. The domes  808  may have any suitable shape and may be formed from any suitable material, including metal, rubber, plastic, carbon fiber, or the like. 
       FIG.  8 C  shows the top case  800  with plate springs  810  aligned with and attached to a bottom surface of the protrusions  802 . The plate springs  810  may be strips or pads of metal, carbon fiber, plastic, or any other suitable material, and may be attached to the top case  800  in any suitable manner, including adhesives, fusion bonding, mechanical attachments, or the like. In some cases, the plate springs  810  may conform to the shape of the underside of the protrusions  802  such that the plate springs  810  are in substantially complete contact with the bottom surface of the top case  800 . The plate springs  810  may resist deformation in a manner that imparts a returning force on the protrusions  802 . As noted above, the returning force may be configured to return a buckled or collapsed protrusion to a rest (e.g., upwardly protruding) position, or to increase, change, or modify a force response of a non-buckling protrusion or top case. 
       FIG.  8 D  shows a partial cross-sectional view of an example top case  812  that defines protrusions  814 , and in which key mechanisms  816  are positioned below the protrusions. The protrusions  814  in the top case  812  may be configured to buckle or collapse, as described with respect to  FIGS.  6 A- 6 C , or deform without buckling or collapsing, as described with respect to  FIGS.  4 A- 4 C . The top case  812  may be the same as or similar to other top cases described herein. For example, the top case  812  may be glass having a thickness of about 40 microns or less. 
     Like the resilient members in  FIGS.  8 A- 8 C , the key mechanisms  816  may interact with the protrusions  814  to, for example, impart a returning force on the protrusions  814  to bias the protrusions  814  in an undepressed position and/or to provide tactile feedback (e.g., a “click”) when the protrusion  814  is actuated. 
     The key mechanisms  816  may include an actuation member  818 , a substrate  824 , a collapsible member  822 , and a support mechanism  820  that is configured to support the actuation member  818  and allow the actuation member  818  to move between an undepressed position and a depressed position. The support mechanism  820  may be coupled to the substrate  824  and the actuation member  818 , and may have any suitable configuration. As shown, for example, the support mechanism resembles a scissor mechanism, though other types and configurations are also possible, such as butterfly hinges, linear guides, linkages, and the like. 
     The collapsible member  822  may be any suitable collapsible member, such as a collapsible dome. The collapsible member  822  may be formed from or include conductive materials to allow the collapsible member  822  to act as a switch to detect or register actuations of a key region defined by a protrusion  814 . For example, when the collapsible member  822  is collapsed (e.g., by a user pressing on the protrusion  814 ), the collapsible member  822  may contact electrical contacts or electrodes on the substrate  824 , thereby closing a circuit and allowing a computing device to register a key input. Moreover, the collapsible member  822  may provide the biasing force to the actuation member  818  and, by extension, the protrusion  814 , and the collapse of the collapsible member  822  when the protrusion  814  is pressed and deformed may provide the tactile “click” to the key region. 
     The actuation member  818  may contact an underside of a protrusion  814  and may be adhered or otherwise bonded to the top case  812 , or it may be not adhered or bonded to the top case  812 . In some cases, the actuation member  818  may define a glyph or symbol on a top surface of the actuation member  818 , which may be visible through the top case  812 . Because the glyph or symbol indicating the function of that particular key region is below the transparent (e.g., glass) top case  812 , the glyph or symbol may be protected from wear and abrasion as a result of typing inputs on the key region. 
     While the foregoing discussion describes various aspects of local deformation and local buckling of key regions, a glass top case may also or instead be configured to provide global buckling. For example,  FIG.  9 A  shows a top case  900  having a shape that is configured to provide global buckling. More particularly, substantially the entire top case  900 , or at least the portion of the top case  900  corresponding to a keyboard region, may be configured to buckle in response to forces applied to a top surface of the top case  900 . The particular shape of the top case  900  in  FIG.  9 A  (e.g., a generally dome-shaped or convex shape) is merely exemplary, and other shapes or configurations may instead be used to produce a globally-buckling top case. 
       FIGS.  9 B- 9 E  show a partial cross-sectional view of a top case  900 , corresponding to a view of the top case  900  along section D-D in  FIG.  9 A . While  FIGS.  9 B- 9 E  generally agree with the shape of the top case  900  shown in  FIG.  9 A , it will be understood that this is merely an example shape, and the cross-sectional shape of a top case may differ from that shown depending on the particular shape or configuration used for a globally-buckling top case. 
     As shown in  FIGS.  9 B- 9 C , when the top case  900  is depressed in one area (e.g., by a user&#39;s finger  902 , a stylus, or another object), the entire buckling portion of the top case  900  collapses or buckles, thus producing a tactile click response when a particular force threshold is reached. When the user&#39;s finger  902  is removed from the top case  900 , the buckling portion of the top case  900  returns to a rest (e.g., upwardly protruding) position (as shown in  FIG.  9 D ). When a force is applied on a different area of the top case  900 , as shown in  FIGS.  9 D- 9 E , the top case  900  may collapse or buckle in substantially the same manner as shown in  FIG.  9 C . In this way, a user may click or press anywhere on the top case  900  and detect a tactile click. Global buckling as shown and described in  FIGS.  9 A- 9 E  may provide haptic, tactile feedback to a keyboard region. For example, keys may be struck sequentially while typing (e.g., one after another). Accordingly, it may not be necessary for each key region to produce a buckling response, as the global buckling response may be capable of producing a tactile click for each sequential key strike. Further, a globally buckling top case may be used with a top case having a substantially flat or planar top surface, or a top case having physically distinguished key regions, such as pads, protrusions, recesses, or the like. 
     In some cases, a top case may be configured to produce both local and global buckling responses in response to force inputs.  FIGS.  10 A- 10 D  relate to a multi-layer glass top case  1000  that produces both local and global buckling responses. With reference to  FIG.  10 A , which is a partial cross-sectional view of the top case  1000 , corresponding to a view of a top case along line B-B in  FIG.  1   , the top case  1000  may include a first glass layer  1004 . The first glass layer  1004  may define an array of protrusions  1006  that define key regions of a keyboard. The first glass layer  1004  may be substantially similar in materials, dimensions, and function to the top case  700  described with respect to  FIGS.  7 A- 7 B . For example, the first glass layer  1004  may be formed from a strengthened glass having a thickness less than about 40 μm, and each protrusion  1006  may be configured to buckle or collapse in response to application of a force to produce a first tactile click. 
     The top case  1000  may also include a second glass layer  1002 . The second glass layer  1002  may be substantially similar to the top case  900  ( FIGS.  9 A- 9 E ), and may be formed of the same materials and provide the same functions. For example, the second glass layer  1002  may be formed from strengthened glass and may have a shape that provides a buckling response when forces are applied to different areas on the second glass layer  1002 . The first glass layer  1004  may be above the second glass layer  1002 , and may be attached to the second glass layer  1002 . For example, the first glass layer  1004  may be bonded, adhered, fused, or otherwise attached to the second glass layer  1002 . The spaces under the protrusions  1006  may be empty or they may be occupied by a material. For example, the spaces under the protrusions  1006  may be under vacuum, or filled with air, a liquid, a resilient material (e.g., a gel, silicone, etc.), or any other suitable material. 
       FIGS.  10 B and  10 C  show how the two glass layers of the top case  1000  may deflect in response to application of a force input (from a user&#39;s finger  1008 , for example), and  FIG.  10 D  shows an example force versus deflection curve  1010  for the dual-layer top case  1000 . In particular, the top case  1000  may produce buckling responses at two different force levels, each corresponding to a buckling of a different one of the layers.  FIG.  10 B  shows a finger  1008  deforming a protrusion  1006  of the first glass layer  1004 , which may correspond to a path in the force versus deflection curve  1010  from the point  1012  to the point  1014 . This force response may correspond to a typical typing input, and may produce a tactile click indicating that the key region has been actuated and the input has been detected. If the user continues to increase the force after the protrusion  1006  is deformed (e.g., past the point  1014  in the curve  1010 ), the second glass layer  1002  may ultimately buckle or collapse, as shown in  FIG.  10 C . This additional force may correspond to the path from point  1014  to point  1016  on the curve  1010 . When the second glass layer  1002  buckles, the keyboard may register a different input, and thus perform a different action, than when the first glass layer  1004  buckles. For example, when a buckling of a protrusion or key region of the first glass layer  1004  is detected (e.g., at or around point  1014 ), the keyboard may register a selection of a character key and cause a lower case character to be displayed on a display. When a buckling of the second glass layer  1002  is detected (e.g., at or around point  1016 ), the keyboard may replace the lower case character with an upper case character. Other functions may also or instead be associated with each of the first and second buckling points. 
     As described herein, a glass top case may be made sufficiently thin that force inputs from user&#39;s fingers, such as typing inputs, can locally deform the glass. This can be used to provide “moving” key regions that are easier and more intuitive to type on, and even to produce tactile clicks and other haptic feedback. In some cases, the flexibility and/or deformability of a thin glass top case may be used in conjunction with actuators to selectively form protrusions or recesses to define key regions. For example,  FIGS.  11 A- 11 B  show a top case  1100 , which may be formed of a thin glass having dimensions and compositions as described herein, with an array of key regions  1102  defined by selectively formed protrusions. In particular,  FIG.  11 A  shows the top case  1100  having key regions  1102  that are substantially flush with the remaining portion of the top case  1100 .  FIG.  11 B  shows the top case  1100  when actuators below or otherwise associated with the key regions  1102  are extended, thus producing protruding key regions  1102  on the top case  1100 . 
     The key regions  1102  may be retracted ( FIG.  11 A ) or extended ( FIG.  11 B ) for various reasons. For example, if the top case  1100  is incorporated into a laptop computer (e.g., the device  100 ,  FIG.  1   ), the key regions  1102  may be extended when the computer is opened (e.g., the display portion  102  is rotated up into a viewable position) to allow a user to apply typing inputs. As another example, the key regions  1102  may be extended when the device  100  is in a text entry mode, such as when a word processor or other application that accepts text input is active on the device  100 . On the other hand, the key regions  1102  may be retracted when the device is closed or closing, which allows the closed device to occupy less space. Thus, because the key regions  1102  can be selectively extended and retracted, they can be extended when the keyboard is in use or potentially in use, thereby providing a superior typing experience, and can be retracted when the keyboard is not in use so that the keyboard assembly occupies less space and the overall size of the device  100  is reduced. 
     While  FIGS.  11 A- 11 B  show all of the key regions  1102  either retracted or extended, the key regions  1102  may be individually controlled so that one or more key regions may be retracted while one or more other key regions are extended (or vice versa). Moreover, as shown, the top case  1100  in  FIG.  11 A  has a substantially planar top surface, though this is merely one example. In other cases, when the key regions  1102  are retracted, they protrude less than when the key regions  1102  are extended but are not flush with surrounding areas of the top case  1100 . 
     The top case  1100  may be substantially planar when there are no forces acting on the top case (e.g., from internal actuators), or the top case may define raised key regions when there are no forces acting on the top case. That is, the neutral state of the top case  1100  may be substantially planar, and the raised key regions may be formed by deforming the top case  1100  with the actuators. In other cases, the neutral state of the top case  1100  may include raised key regions, and the top case  1100  may be made substantially planar (or the protrusions may be lessened in size) by applying retracting forces with the actuators. 
     Various types of actuators or other mechanisms may be used to extend and/or retract key regions of a glass top case. For example,  FIGS.  12 A- 12 B  are partial cross-sectional views of an electronic device, viewed along line E-E in  FIG.  11 B , showing example mechanical actuators  1200  that may be positioned under the top case  1100 . The mechanical actuators  1200  may include plungers  1206  that engage a bottom surface of the top case  1100  to locally deform the key regions  1102  when the actuators  1200  are extended. The actuators  1200  may be any suitable type of actuators, including solenoids, hydraulic actuators, pneumatic actuators, lead screws, cams, etc. In some cases, the plungers  1206  may be bonded, adhered, or otherwise fixed to the bottom surface of the top case  1100 , which may allow the actuators  1200  to further retract the key regions  1102  to form cavities relative to the remaining portions of the top case  1100 . 
     The actuators  1200  may be supported by a base  1202 , which may be part of a housing (e.g., bottom case  110 ,  FIG.  1   ), or any other component or structure of an electronic device. Furthermore, the top case  1100  may be supported by support structures  1204  that brace or otherwise support the top case  1100  relative to another part of the device in which it is integrated, such as the base  1202 . The support structures  1204  may be adhered to or bonded to the top case  1100  to isolate and/or localize deformations produced by the actuators  1200 , thereby allowing the actuators  1200  to produce discrete protrusions for the different key regions  1102 , rather than simply lifting the entire top case  1100 . 
     Despite the presence of the actuators, the key regions  1102  of the top case  1100  may locally deflect in response to applied forces. For example,  FIG.  12 C  shows a key region  1102  of the top case  1100  deflecting in response to a force applied by a finger  1210 . While  FIG.  12 C  shows the key region  1102  deflecting to form a recess, this is merely one example configuration. In other cases, the key region  1102  may deflect from a protruding configuration (as shown in  FIG.  12 B ) to a substantially planar configuration (e.g., as shown in  FIG.  12 A ), or to a protruding configuration that is lower than that shown in  FIG.  12 B . 
     The actuators  1200  may be configured to remove or reduce the force applied to the top case  1100  (or produce a reverse force tending to retract the key region  1102 ) when a force is detected on the key region  1102 . In some cases, the actuators  1200  may be used to impart a returning force to the key region  1102 , such as to provide a desired tactile feel to the key regions  1102  and/or to return a collapsing or buckling key region into its undeflected or undeformed position. In some cases, the actuators  1200  may be haptic actuators that produce haptic outputs. For example, the actuators  1200  may produce a force response that is substantially similar to the force versus deflection curves discussed with respect to  FIG.  6 C or  10 D , producing a tactile click that may be felt and/or heard by a user. In some cases, the actuators  1200  produce a motion or vibration that is perceptible by the user and provides the tactile response (e.g., “click”). Such haptic outputs may be used in conjunction with both buckling and non-buckling style top cases. 
     Magnetic actuators may be used instead of or in addition to mechanical actuators. For example,  FIGS.  13 A- 13 C  are partial cross-sectional views of an electronic device, viewed along line E-E in  FIG.  11 B , showing example magnetic actuators  1300  that may be positioned under the top case  1100  to extend and/or retract the key regions  1102 .  FIG.  13 A  shows the top case  1100  when the key regions  1102  are retracted, and  FIG.  13 B  shows the top case  1100  with the key regions  1102  extended.  FIG.  13 C  shows the top case  1100  when a key region  1102  is locally deflected in response to a force applied by a finger  1210 . 
     The magnetic actuators  1300  may each include a first magnetic element  1301  and a second magnetic element  1302 . The first and second magnetic elements  1301 ,  1302  may be any of magnets (e.g., permanent magnets, rare earth magnets, electromagnets, etc.) magnetic materials, magnetizable materials, ferromagnetic materials, metals, or the like. The first and second magnetic elements  1301 ,  1302  may be selectively powered or magnetized to produce repulsive forces (as shown in  FIG.  13 B ) or attractive forces (as shown in  FIG.  13 A ). In some cases, magnets or magnetic materials may be selectively magnetized and demagnetized to produce repulsive or attractive forces (or no forces) by subjecting a magnetic material to a particular magnetic field. This may allow the magnetic elements  1301 ,  1302  to produce continuous forces without requiring constant application of energy or electricity to an electromagnet. In some cases, the magnetic actuators  1300  may include shields, shunts, inducing coils, and/or other components to facilitate selective magnetization and demagnetization, or to otherwise operate the magnetic actuators  1300 . 
     The magnetic actuators  1300  may provide the same or similar functions to the mechanical actuators described above. For example, the magnetic actuators  1300  may be configured to impart a returning force to a top case with buckling or non-buckling protrusions. As another example, the magnetic actuators  1300  may be configured to produce tactile clicks that may be felt and/or heard by a user. As noted above, such actuator-produced haptic outputs may be used in conjunction with both buckling and non-buckling style top cases. 
     Piezoelectric actuators may also be used to selectively extend and retract protruding key regions. For example,  FIGS.  14 A- 14 B  are partial cross-sectional views of an electronic device, viewed along line E-E in  FIG.  11 B , showing example piezoelectric actuators  1400  that may be positioned under the top case  1100  to locally deform the top case  1100  to extend and/or retract the key regions  1102 .  FIG.  14 A  shows the top case  1100  when the key regions  1102  are extended, and  FIG.  14 B  shows the top case  1100  with a key region  1102  retracted.  FIG.  14 B  shows the key region  1102  retracted to form a cavity in the top surface of the top case  1100 , though this is merely one example configuration, and the piezoelectric actuators  1400  may instead retract the key regions  1102  to a substantially flush configuration. 
     The piezoelectric actuators may include actuator strips  1402 , which may be formed from a piezoelectric material. Force-spreading layers  1404  may be disposed between the actuator strips  1402  and the bottom surface of the top case  1100  (and directly under or proximate the key regions  1102 ). The force-spreading layers  1404  may increase the area of influence of the actuator strips  1402 . More particularly, the force-spreading layers  1404  may increase the area of the top case  1100  that may be deformed by the actuator strips  1402 . The force-spreading layers  1404  may be formed from or include any suitable material, such as silicone, metal, glass, elastomeric materials, polymers, or the like. 
     As depicted in  FIG.  14 A , a voltage may be applied across the piezoelectric material of an actuator strip  1402  causing the actuator strip  1402  to shrink or reduce in length. If the actuator strip  1402  is not allowed to shear with respect to the top case  1100 , the change in length may produce a raised or protruding key region  1102 . The localized deformation may also be characterized as convex or proud of the top case  1100 . 
     As depicted in  FIG.  14 B , a voltage may be applied across the piezoelectric material of the actuator strip  1402  causing the actuator strip  1402  to grow or increase in length. Similar to the previous example, if the actuator strip  1402  is not allowed to shear with respect to the top case  1100 , the change in length may produce a depressed or recessed key region  1102 . The localized deformation may also be characterized as concave or recessed. 
     The top case  1100  in  FIGS.  14 A- 14 B  may have the protrusions formed therein, and the protrusions may be configured as buckling or collapsing protrusions that produce a tactile click, as described with respect to  FIGS.  6 A- 6 C . In such cases, and similar to the mechanical and magnetic actuators described above, the piezoelectric actuators  1400  may be configured to impart a returning force to the protrusions so that they return to a neutral, undeformed position after buckling or collapsing in response to a force input. 
     When actuators are used to selectively locally deform a top case, support structures may be positioned below the top case or otherwise configured to localize and isolate the deformations produced by the actuators. Example supports are shown and described with respect to  FIGS.  12 A- 13 C . In some cases, however, multiple actuators may cooperate to produce local deformations, such as deformations of only a single key region, without support structures that surround or isolate deformations of particular key regions. 
       FIGS.  15 A- 15 B  show an example of how actuators may cooperate to produce localized deformations in a top case  1500  without support structures that isolate the effect of each actuator. For example,  FIG.  15 A  shows the top case  1500  (which may be a glass top case having the dimensions and/or properties of any of the top cases described herein) with a key region  1502  protruding from a surrounding area  1504 .  FIG.  15 B  shows a partial cross-sectional view of a device having the top case  1500 , viewed along line F-F in  FIG.  15 A . Actuators  1506 - 1 , . . . ,  1506 - n  positioned below the top case  1500  act on the top case  1500  to impart forces on the top case  1500  to produce deformations. For example, to produce the protruding key region  1502 , without using supports that extend around or define the key region  1502 , the actuator  1506 - 3  may extend, forcing the key region  1502  upwards. Without support structures, extended actuator  1506 - 3  may cause a protrusion larger than a single key region. Accordingly, actuators in a surrounding or nearby area  1504 , including actuators  1506 - 2  and  1506 - 4 , for example, may retract, thus imparting a counteracting force to the top case  1500  that will help produce a more distinctive, localized protrusion for the key region  1502 . 
     The surrounding region  1504  is shown as being retracted relative to a remainder of the top case  1500 . However, this is merely for illustration, and the surrounding actuators may instead produce counteracting forces that maintain the surrounding region  1504  substantially unmoved relative to an undeformed height or position of the top case  1500 . Also, while the actuators  1506  are shown as magnetic actuators, other types of actuators may be used in a similar manner to help localize deformations from other actuators, including, for example, mechanical actuators, piezoelectric actuators, or the like. 
     Cooperating actuators as described above may not be sufficient to allow all of the key regions to be retracted or extended at the same time. Accordingly, these techniques may be implemented in devices where an entire keyboard of protrusions does not need to be produced simultaneously. For example, in some cases, a keyboard may produce local deformations for individual key regions only when that key region is being pressed or is about to be pressed (as determined, for example, by optical sensors, touch sensors, presence sensors, or the like). Thus, the actuators  1506 , for example, may cooperate to cause the key region  1502  to protrude immediately before and/or while that key is being pressed, and then may cooperate to cause another key region to protrude before and/or while the other key region is being pressed. 
     While the actuators described herein are primarily described as producing localized deformations in a glass top case, these (or other) actuators may also be used to produce other haptic outputs. For example, actuators may produce movement, vibrations, pulses, oscillations, or any other motion or tactile output that can be felt by a user through the top case. Such haptic outputs may be used, for example, to indicate when an input has been registered, or to simulate the sensation of a tactile “click” of a buckling dome or spring. In the latter case, such haptic actuators may be used in conjunction with top cases that do not have buckling or collapsing shapes to provide a familiar tactile feel to the key regions of the top case. 
     As described above, support structures may be incorporated into an electronic device to support a top case and to optionally help localize deflections of the top case to individual key regions or subsets of the key regions.  FIGS.  16 A- 16 B  are partial cross-sectional views of an electronic device, and in particular a base portion of an electronic device, corresponding to a view of a top case along section B-B in  FIG.  1   . These figures show examples of top cases supported by support structures. For example,  FIG.  16 A  shows a top case  1600 , such as a glass top case, attached to a bottom case  1602 . The bottom case  1602  may correspond to the bottom case  110 ,  FIG.  1   . The top case  1600  may define an array of key regions  1604 . As shown in FIG.  16 A, top case  1600  defines substantially planar top and bottom surfaces. However, the key regions  1604  may correspond to any of the key regions described herein, including raised or protruding key regions, recessed key regions, collapsing or buckling key regions, key regions defined by channels or features on the bottom surface of the top case, or the like. 
     The electronic device shown in  FIG.  16 A  includes support structures  1606  inside the base portion. The support structures  1606  are positioned to support regions of the top case  1600  between adjacent key regions  1604  (e.g., in non-key regions of the top case  1600 ). As shown, each key region  1604  may be isolated from other key regions by a support structure  1606 , thus isolating and/or localizing deflections to individual key regions caused by user inputs applied to the key regions. In some cases, the support structures  1606  may define closed regions that fully extend around or define an outer perimeter of a key region  1604 . For example, the support structures  1606  may resemble a keyboard web with openings defining individual key regions. The openings may have any shape or configuration, such as square, circular, oblong, rectangular, or any other suitable shape. 
     As noted,  FIG.  16 A  shows an example in which the support structures are positioned between each key region.  FIG.  16 B  shows a configuration of an electronic device in which there is not a support structure between each key region, but rather multiple key regions between support structures. In particular,  FIG.  16 B  shows a base portion with a top case  1610  (e.g., a glass top case) attached to a bottom case  1612 . The top case  1610  defines key regions  1604  (which may have any shape described herein, as noted above with respect to the top case  1600 ). Support structures  1616  contact the underside of the top case  1610  to support the top case, localize deflection, and the like. 
     The support structures  1606 ,  1616  are shown extending from the top cases  1600 ,  1610  to the bottom cases  1602 ,  1612 . However, this is merely an example configuration. In other configurations, at least some of the support structures  1606 ,  1616  do not directly contact the bottom case, but instead contact a different internal component or structure of an electronic device. In yet other configurations, the bottom cases  1602 ,  1612  and the support structures  1606 ,  1616  are a unitary structure (e.g., they form a monolithic component). For example, the bottom cases may be formed (e.g., machined or cast) with posts or walls extending upwards from the surfaces of the bottom cases. In yet other configurations, the support structures  1606 ,  1616  are part of a web, such as a sheet having an array of openings therein. The openings may correspond to or substantially define single key regions or multiple key regions. Where the support structures  1606 ,  1616  are defined by a web, the web may be adhered to a bottom surface of the top cases  1600 ,  1610 . 
     Using a glass member for a top case, and more particularly for the input surface of a keyboard, may also provide unique opportunities for forming wear-resistant glyphs (or other symbols) on the individual key regions.  FIGS.  17 A- 17 D  illustrate various techniques for forming glyphs on a continuous glass (or other transparent material) top case. 
       FIG.  17 A  is a detail view of region C-C of the top case  112  of the computing device  100  ( FIG.  1   ), showing an example key region  1702 . The key region  1702  may correspond to one of the key regions  115  of the keyboard region  114 . The key region  1702  may include a glyph  1704 , which may indicate the function of the key region  1702 . As described herein, the glyph  1704  may be defined on a bottom surface of the top case  112 , such that the top surface of the top case  112  that a user touches when typing is simply a plain glass surface. 
       FIGS.  17 B- 17 D  are partial cross-sectional views of the top case  112 , viewed along line G-G in  FIG.  17 A , showing various example techniques for forming glyphs on the bottom surface of the top case  112 .  FIG.  17 B , for example, shows a mask layer  1706  disposed on the bottom surface of the top case  112 . The mask layer  1706  may include openings, such as the opening  1708  in  FIG.  17 B , that define the glyphs. The mask layer  1706  may have a contrasting visual appearance to the opening  1708  (or to whatever is visible through the opening  1708 ) to allow the glyph  1704  to be visually distinguished from the surrounding area of the key region  1702 . The mask layer  1706  may be any suitable material, such as paint, dye, ink, a film layer, or the like, and may be any suitable color. The mask layer  1706  may also be opaque to occlude underlying components, materials, structures, adhesives, or other internal components of the device  100 . In some cases, another layer or material is positioned below the opening  1708  so that the underlying layer or material is visible through the top case  112 . 
       FIG.  17 C  shows an example in which the opening in the mask layer  1706  has an additional layer  1710  positioned therein. The additional layer  1710  may have a visual appearance that contrasts that of the mask layer  1706  to define the glyph. The additional layer  1710  may be any suitable material, such as paint, dye, ink, a film layer, or the like, and may be opaque or translucent. In some cases, the additional layer  1710  may be a semi-transparent mirror material (e.g., a metal film) that can be reflective under some external lighting conditions and transparent (or at least partially transparent or translucent) under other external lighting conditions. For example, if a light source below the additional layer  1710  is active, the additional layer  1710  may appear to a user to be backlit (e.g., the glyph  1704  may appear illuminated). 
       FIG.  17 D  shows an example in which the bottom surface of the top case  112  has a contrasting surface finish or other treatment  1712  in the mask layer  1706  to define the glyph  1704 . For example, the portion of the bottom surface of the top case  112  that corresponds to a glyph opening may have a different roughness, texture, or other physical characteristic, than the surrounding non-glyph areas. The surface finish or treatment may be produced in any suitable way, such as etching (e.g., chemical etching, laser etching, plasma etching), machining, grinding, abrasive blasting, or the like. When viewed through the top surface of the top case  112 , the different surface finish or treatment  1712  may have a distinct visual appearance than the surrounding areas. In some cases, additional layers may be used in conjunction with the top case  112  shown in  FIG.  17 D . For example, a mask layer  1706  (as shown in  FIGS.  17 B- 17 C ) may be applied to the non-glyph regions of the top case  112  (as discussed above), and an additional layer  1710  may be applied on the surface finish or treatment  1712 . 
     While the foregoing examples show the glyphs defined by material on the bottom surface of the top case  112 , these are merely some example techniques for forming the glyphs. In some cases, glyphs may be defined on the top surface of the top case  112  using the same or similar configurations as those shown in  FIGS.  17 B- 17 D  (e.g., the mask layers, additional layers, and surface treatments may be applied to the top surface). In some cases, both the top and bottom surfaces of the top case  112  may include coatings, inks, dyes, paints, surface treatments, or the like, to define the glyphs (or any other graphical objects desired to be visible on the top case  112 ). 
     Glass members for keyboard surfaces may be coupled to an electronic device in various ways. For example, as shown in  FIG.  1   , a glass top case  112  may define substantially all of a top surface of a computing device, and may be coupled directly to a bottom case  110 .  FIGS.  18 A- 18 D  illustrate other example techniques for coupling a glass member for a keyboard surface to a computing device. 
       FIG.  18 A  depicts a computing device  1800  (or simply “device  1800 ”) that may include a glass member defining a keyboard surface. In particular, a base portion  1804  of the device  1800  may include a top case  1812  and a separate keyboard member  1811  that is formed at least partially from glass and that defines a keyboard region  1814  of the device  1800 . The device  1800  may otherwise be the same as or similar to the device  100  described above, and aspects of the device  100  that are discussed herein will be understood to apply equally to the device  1800 . 
     The keyboard member  1811  may have any of the properties and/or employ any of the features described herein with respect to other top cases, including deformable protrusions, buckling configurations, underlying resilient members, and the like. For example, the keyboard member  1811  may be formed from one or more layers of strengthened glass (e.g., chemically strengthened, ion-exchanged, heat-treated, tempered, annealed, or the like). The glass may be thinner than about 100 μm, thinner than about 40 μm, or thinner than about 30 μm. The keyboard member  1811  may be configured to locally deflect or deform any suitable amount in response to a typing force. For example, the keyboard member  1811  may be configured to locally deflect about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, or any other suitable amount, in response to a sample typing force (e.g., 250 g, 500 g, 1 kg, etc.). 
     The top case  1812  may be formed from or include any suitable material, such as glass, plastic, metal (e.g., aluminum, stainless steel, magnesium, an alloy, etc.). The top case  1812  may also define an opening in which the keyboard member  1811  may be positioned. The top case  1812  may also define or include input regions such as a touch-input region  1816 . While both the keyboard member  1811  and the top case  1812  may be formed from glass, they may be formed from different glass materials or have other different properties or characteristics. For example, the top case  1812  may be thicker than the keyboard member  1811  to provide for additional strength and/or stiffness. As another example, the top case  1812  may be formed from a glass having a higher stiffness than the glass of the keyboard member  1811 . In this way, the various glass components may be tailored for the particular design targets for each component. More particularly, the thicker top case  1812  may provide greater structural stability, but would not provide sufficient local deflection to provide a good typing experience. Accordingly, the thinner keyboard member  1811  may provide the deformability that provides a desired typing experience, while the thicker top case  1812  provides a desired structural strength and/or stiffness. 
       FIGS.  18 B- 18 D  are partial cross-sectional views of the device  1800 , viewed along line H-H in  FIG.  18 A , showing example techniques for joining the keyboard member  1811  to the top case  1812 . In  FIG.  18 B , for example, the top case  1812  defines a ledge that supports a peripheral portion of the keyboard member  1811 . An adhesive  1815  may be positioned on the ledge to secure the keyboard member  1811  to the top case  1812 . The adhesive  1815  may be any suitable adhesive or bonding agent, including pressure sensitive adhesive (PSA), heat sensitive adhesive (HSA), epoxy, contact cement, or the like. As shown in  FIGS.  18 B- 18 D , a top surface of the top case  1812  and a top surface of the keyboard member  1811  may be substantially flush (e.g., coplanar), thereby producing a substantially flat top surface to the base portion  1804  of the device  1800 . 
       FIG.  18 C  shows an example in which the keyboard member  1811  is fused to the top case  1812  along a fused region  1813 . The keyboard member  1811  may be fused to the top case  1812  by at least partially melting or softening the top case  1812  and the keyboard member  1811  to form the fused region  1813 . The fusion may be achieved using any suitable process, including laser welding, ultrasonic welding, direct heat and/or flame application, pressure, or the like. 
       FIG.  18 D  shows an example in which the keyboard member  1811  defines a ledge that is adhered or otherwise bonded to the bottom surface of the top case  1812 . The keyboard member  1811  may be bonded to the top case  1812  with an adhesive  1818 , which may be any suitable adhesive or bonding agent, including pressure sensitive adhesive (PSA), heat sensitive adhesive (HSA), epoxy, contact cement, or the like. 
       FIG.  19    depicts an example schematic diagram of an electronic device  1900 . By way of example, device  1900  of  FIG.  19    may correspond to the computing device  100  shown in  FIG.  1    and/or the computing device  1800  shown in  FIG.  18 A . To the extent that multiple functionalities, operations, and structures are disclosed as being part of, incorporated into, or performed by the device  1900 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the device  1900  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. The electronic device  1900  may include a thin glass top case, as described herein, on which distinct key regions may be formed. For example, key regions of a keyboard may be defined by protrusions formed into the glass top case, as described herein. 
     As shown in  FIG.  19   , the device  1900  includes one or more processing units  1902  that are configured to access a memory  1904  having instructions stored thereon. The instructions or computer programs may be configured to perform one or more of the operations or functions described with respect to the device  1900  (and/or any device described herein, such as the devices  100 ,  1800 ). For example, the instructions may be configured to control or coordinate the operation of one or more displays  1920 , one or more touch sensors  1906 , one or more force sensors  1908 , one or more communication channels  1910 , and/or one or more actuators  1912 . 
     The processing units  1902  of  FIG.  19    may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processing units  1902  may include one or more of a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. 
     The memory  1904  can store electronic data that can be used by the device  1900 . For example, a memory can store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing and control signals or data for the various modules, data structures or databases, and so on. The memory  1904  can be configured as any type of memory. By way of example only, the memory  1904  can be implemented as random access memory, read-only memory, Flash memory, removable memory, or other types of storage elements, or combinations of such devices. 
     The touch sensors  1906  (which may be part of a touch and/or force sensing system) may detect various types of touch-based inputs and generate signals or data that are able to be accessed using processor instructions. The touch sensors  1906  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the touch sensors  1906  may be capacitive touch sensors, resistive touch sensors, acoustic wave sensors, or the like. The touch sensors  1906  may include any suitable components for detecting touch-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.), processors, circuitry, firmware, and the like. The touch sensors  1906  may be used in conjunction with various input mechanisms to detect various types of inputs. For example, the touch sensors  1906  may be used to detect touch inputs (e.g., gestures, multi-touch inputs, taps, etc.), keyboard inputs (e.g., actuations and/or localized deformations of key regions of a glass top case), and the like. The touch sensors  1906  may be integrated with or otherwise configured to detect touch inputs on and/or deformations of a top case of a computing device (e.g., the top cases  112 ,  1812 , or any other top case discussed herein) or on another component configured to detect touch inputs, such as the keyboard member  1811  ( FIG.  18 A ). The touch sensors  1906  may operate in conjunction with the force sensors  1908  to generate signals or data in response to touch inputs or deformations of key regions or other areas of a glass top case. 
     The force sensors  1908  (which may be part of a touch and/or force sensing system) may detect various types of force-based inputs and generate signals or data that are able to be accessed using processor instructions. The force sensors  1908  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the force sensors  1908  may be strain-based sensors, piezoelectric-based sensors, piezoresistive-based sensors, capacitive sensors, resistive sensors, or the like. The force sensors  1908  may include any suitable components for detecting force-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The force sensors  1908  may be used in conjunction with various input mechanisms to detect various types of inputs. For example, the force sensors  1908  may be used to detect clicks, presses, or other force inputs applied to a trackpad, a keyboard, key regions of a glass top case, a touch- or force-sensitive input region, or the like, any or all of which may be located on or integrated with a top case of a computing device (e.g., the top cases  112 ,  1812  or any other top case discussed herein) or with a keyboard member (e.g., the keyboard member  1811 ). The force sensors  1908  may operate in conjunction with the touch sensors  1906  to generate signals or data in response to touch- and/or force-based inputs or local deformations of a glass top case. 
     The device  1900  may also include one or more actuators  1912 . The actuators  1912  may include one or more of a variety of haptic technologies such as, but not necessarily limited to, mechanical actuators, solenoids, hydraulic actuators, cams, piezoelectric devices, magnetic actuators, and so on. In general, the actuators  1912  may be configured to provide returning forces to key regions of a glass top case and/or to provide distinct feedback (e.g., tactile clicks) to a user of the device. For example, the actuators  1912  may be adapted to produce a knock or tap sensation and/or a vibration sensation, to produce a biasing force that biases a protrusion towards an undepressed position, or the like. 
     The one or more communication channels  1910  may include one or more wireless interface(s) that are adapted to provide communication between the processing unit(s)  1902  and an external device. In general, the one or more communication channels  1910  may be configured to transmit and receive data and/or signals that may be interpreted by instructions executed on the processing units  1902 . In some cases, the external device is part of an external communication network that is configured to exchange data with wireless devices. Generally, the wireless interface may include, without limitation, radio frequency, optical, acoustic, and/or magnetic signals and may be configured to operate over a wireless interface or protocol. Example wireless interfaces include radio frequency cellular interfaces, fiber optic interfaces, acoustic interfaces, Bluetooth interfaces, infrared interfaces, USB interfaces, Wi-Fi interfaces, TCP/IP interfaces, network communications interfaces, or any conventional communication interfaces. 
     As shown in  FIG.  19   , the device  1900  may include a battery  1914  that is used to store and provide power to the other components of the device  1900 . The battery  1914  may be a rechargeable power supply that is configured to provide power to the device  1900  while it is being used by the user. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. Also, when used herein to refer to positions of components, the terms above and below, or their synonyms, do not necessarily refer to an absolute position relative to an external reference, but instead refer to the relative position of components with reference to the figures.

Metadata:
Filing Date: 20220728
Publication Date: 20230404
Grant Date: 20230404
Priority Date: 20170726
Inventors: WANG, PAUL X.
LEHMANN, Alex J.
GAO, ZHENG
Assignee: APPLE INC
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