PATENT DOCUMENT

Publication Number: US-12193839-B2
Application Number: US-202117315141-A
Country: US
Kind Code: B2

Title: Wearable electronic device with glass shell

Abstract:
A wearable electronic device may include a display and a housing. The housing may include a chassis defining a first portion of a rear exterior surface of the wearable electronic device, a first portion of a side exterior surface of the wearable electronic device, and an internal wall. The housing may also include a glass shell defining a front wall positioned over the display and defining a front exterior surface of the wearable electronic device and a side wall extending from the front wall and overlapping the internal wall, the side wall defining a second portion of the side exterior surface of the wearable electronic device. The wearable electronic device may also include a touch sensing system within the housing and configured to detect a touch input applied to the front exterior surface of the wearable electronic device.

Claims:
What is claimed is: 
     
       1. A wearable electronic device comprising:
 a display; 
 a housing comprising:
 a chassis defining:
 a rear portion defining a first portion of a rear exterior surface of the wearable electronic device; and 
 an internal wall extending from the rear portion; 
 
 a glass shell defining:
 a front wall positioned over the display and defining a front exterior surface of the wearable electronic device; and 
 a side wall extending from the front wall and defining:
 a convex side exterior surface of the wearable electronic device; and 
 a concave interior surface opposite the convex side exterior surface, a portion of the side wall overlapping a portion of the internal wall of the chassis such that a gap is defined between the concave interior surface of the side wall and the internal wall of the chassis; and 
 
 
 an adhesive positioned in the gap defined between the concave interior surface of the side wall and the internal wall of the chassis, the adhesive bonded to the concave interior surface of the side wall and to the internal wall of the chassis; and 
 
 a touch sensing system within the housing and configured to detect a touch input applied to the front exterior surface of the wearable electronic device. 
 
     
     
       2. The wearable electronic device of  claim 1 , wherein:
 the adhesive defines an undercut region; and 
 the concave interior surface of the side wall mechanically interlocks with the undercut region of the adhesive to secure the glass shell to the chassis. 
 
     
     
       3. The wearable electronic device of  claim 2 , wherein the glass shell is secured to the chassis at least in part via a chemical bond between the concave interior surface and the adhesive. 
     
     
       4. The wearable electronic device of  claim 1 , further comprising a compliant member within the housing and in contact with the internal wall and the side wall, the compliant member defining a seal between the internal wall and the side wall and configured to retain the adhesive in the gap. 
     
     
       5. The wearable electronic device of  claim 1 , wherein the side wall extends more than half of a distance from the front exterior surface of the wearable electronic device to the rear exterior surface of the wearable electronic device. 
     
     
       6. The wearable electronic device of  claim 1 , wherein:
 the front wall further defines a front interior surface of the wearable electronic device; 
 the wearable electronic device further comprises an opaque mask material on a portion of the concave interior surface and on a portion of the front interior surface; and 
 the opaque mask material defines a border around an active area of the display. 
 
     
     
       7. The wearable electronic device of  claim 1 , wherein the display defines:
 a first portion configured to display first graphical outputs through the front wall; and 
 a second portion configured to display second graphical outputs through the side wall. 
 
     
     
       8. The wearable electronic device of  claim 1 , wherein the adhesive is formed by flowing a flowable material into the gap and allowing the flowable material to harden. 
     
     
       9. The wearable electronic device of  claim 1 , further comprising an opaque mask material between a portion of the concave interior surface and the adhesive and configured to visually occlude the adhesive. 
     
     
       10. A watch comprising:
 a display; 
 a capacitive touch-sensing system; and 
 a housing surrounding the display and the capacitive touch-sensing system and comprising:
 a chassis defining:
 at least a portion of a rear surface of the watch; 
 a watch band engagement feature; and 
 an internal wall; and 
 
 a glass shell defining:
 a front wall defining a front surface of the watch; 
 a first pair of side walls having a first length and defining a first pair of side surfaces of the watch; and 
 a second pair of side walls having a second length greater than the first length and defining a second pair of side surfaces of the watch, at least one side wall of the second pair of side walls defining a convex exterior surface and a concave interior surface opposite the convex exterior surface, a portion of the at least one side wall overlapping a portion of the internal wall such that a gap is defined between the concave interior surface and the internal wall; 
 
 
 an adhesive positioned in the gap defined between the concave interior surface and the internal wall, the adhesive bonded to the concave interior surface and to the internal wall; and 
 a watch band coupled to the watch band engagement feature. 
 
     
     
       11. The watch of  claim 10 , wherein:
 the chassis is formed from metal and defines:
 a rear wall defining the portion of the rear surface of the watch; and 
 a hole extending through the rear wall; and 
 
 the watch further comprises:
 a sensor cover positioned at least partially in the hole and defining an additional portion of the rear surface of the watch; and 
 a sensor system configured to detect a biological parameter of a user through the sensor cover. 
 
 
     
     
       12. The watch of  claim 10 , wherein the watch band engagement feature includes a slot formed in the chassis. 
     
     
       13. The watch of  claim 10 , wherein the display is configured to display graphical outputs visible through the front wall and through at least one side wall of the second pair of side walls. 
     
     
       14. The watch of  claim 10 , wherein:
 the adhesive defines an undercut; and 
 the concave interior surface of the at least one side wall engages the undercut to mechanically interlock the glass shell to the chassis. 
 
     
     
       15. A wearable electronic device comprising:
 a housing comprising:
 a chassis defining:
 a rear wall defining a first portion of a rear exterior surface of the wearable electronic device; 
 an internal wall extending from the rear wall; and 
 a hole extending through the rear wall; 
 
 a glass shell defining:
 a front wall defining a front surface of the wearable electronic device; and 
 four side walls extending from the front wall, each of the four side walls defining a portion of a respective side surface of the wearable electronic device, at least one side wall of the four side walls defining a convex exterior surface and a concave interior surface opposite the convex exterior surface, a portion of the at least one side wall overlapping a portion of the internal wall such that a gap is defined between the concave interior surface and the internal wall; and 
 
 a sensor cover covering the hole and defining a second portion of the rear exterior surface of the wearable electronic device; 
 
 an adhesive positioned in the gap defined between the concave interior surface and the internal wall, the adhesive bonded to the concave interior surface and to the internal wall 
 a display within the housing; and 
 a biometric sensor system within the housing and configured to detect a biological parameter of a user. 
 
     
     
       16. The wearable electronic device of  claim 15 , wherein the biometric sensor system comprises:
 an optical emitter configured to emit light through a first transparent portion of the sensor cover; and 
 an optical sensor configured to detect, through a second transparent portion of the sensor cover, a portion of the light that is reflected by a portion of the user&#39;s body. 
 
     
     
       17. The wearable electronic device of  claim 16 , wherein the sensor cover comprises:
 a monolithic structure formed from a transparent material; 
 a masked region defining an opaque region of the sensor cover; 
 a first unmasked region defining the first transparent portion of the sensor cover; and 
 a second unmasked region defining the second transparent portion of the sensor cover. 
 
     
     
       18. The wearable electronic device of  claim 15 , further comprising an electrode coupled to the sensor cover and defining a third portion of the rear exterior surface of the wearable electronic device. 
     
     
       19. The wearable electronic device of  claim 18 , wherein:
 the electrode is a first electrode configured to measure a first voltage; 
 the wearable electronic device further comprises a second electrode along an exterior surface of the wearable electronic device and configured to measure a second voltage; and 
 the wearable electronic device is configured to determine an electrocardiogram using the first voltage and the second voltage. 
 
     
     
       20. The wearable electronic device of  claim 19 , wherein the second electrode is positioned along one of the side walls of the four side walls.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a nonprovisional patent application of and claims the benefit of U.S. Provisional Patent Application No. 63/023,961, filed May 13, 2020 and titled “Wearable Electronic Device with Glass Shell,” the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The subject matter of this disclosure relates generally to electronic devices and, more particularly, to housing structures for handheld electronic devices. 
     BACKGROUND 
     Modern consumer electronic devices take many shapes and forms, and have numerous uses and functions. Devices such as mobile phones, tablet computers, and watches, for example, may include touch-sensitive displays, speakers, microphones, batteries, as well as sophisticated processors and other electronics. These and other subsystems may be integrated into compact, handheld and/or wearable products that provide myriad functions while being reliable and capable of withstanding daily use. 
     SUMMARY 
     A wearable electronic device may include a display, a housing that includes a chassis defining a first portion of a rear exterior surface of the wearable electronic device and a first portion of a side exterior surface of the wearable electronic device, a glass shell defining a front wall positioned over the display and defining a front exterior surface of the wearable electronic device, and a side wall extending from the front wall and defining a second portion of the side exterior surface of the wearable electronic device. The wearable electronic device may further include a touch sensing system within the housing and configured to detect a touch input applied to the front exterior surface of the wearable electronic device. 
     The chassis may further define an internal wall, a portion of the side wall may overlap the internal wall and define a concave interior surface, and the wearable electronic device may further include an adhesive bonding the concave interior surface to the internal wall. The adhesive may define an undercut region, and the concave interior surface of the glass shell may mechanically interlock with the undercut region of the adhesive to secure the glass shell to the chassis. The glass shell may be secured to the chassis at least in part via a chemical bond between the concave interior surface and the adhesive. The second portion of the side exterior surface of the wearable electronic device may extend more than half of a distance from the front exterior surface of the wearable electronic device to the rear exterior surface of the wearable electronic device. 
     The wearable electronic device may further include a compliant member within the housing and in contact with the internal wall and the side wall, the compliant member defining a seal between the internal wall and the side wall. 
     The front wall may further define a front interior surface of the wearable electronic device, the wearable electronic device may further include an opaque mask material on a portion of the concave interior surface and on a portion of the front interior surface, and the opaque mask material may define a border around an active area of the display. The display may define a first portion configured to display first graphical outputs through the front wall and a second portion configured to display second graphical outputs through the side wall. 
     A watch may include a display, a capacitive touch-sensing system, and a housing surrounding the display and the capacitive touch-sensing system. The housing may include a glass shell defining a front wall defining a front surface of the watch, a first pair of side walls having a first length and defining a first pair of side surfaces of the watch, and a second pair of side walls having a second length greater than the first length and defining a second pair of side surfaces of the watch. The housing may also include a chassis defining at least a portion of a rear surface of the watch and a watch band engagement feature. The watch may include a watch band coupled to the watch band engagement feature. 
     The chassis may be formed from metal and may define a rear wall defining the portion of the rear surface of the watch and a hole extending through the rear wall. The watch may further include a sensor cover positioned at least partially in the hole and defining an additional portion of the rear surface of the watch and a sensor system configured to detect a biological parameter of a user through the sensor cover. The display may be configured to display graphical outputs visible through the front wall and through at least one side wall of the second pair of side walls. 
     The chassis may define an internal wall, and a first portion of the internal wall may overlap a first portion of one of the side walls of the second pair of side walls. The watch may further include an adhesive positioned in a gap defined between the first portion of the internal wall and the first portion of the side wall of the second pair of side walls. The watch band engagement feature may include a slot formed in the chassis. 
     A wearable electronic device may include a housing that includes a chassis defining a rear wall defining a first portion of a rear exterior surface of the wearable electronic device and a hole extending through the rear wall. The housing may also include a glass shell defining a front wall defining a front surface of the wearable electronic device and four side walls extending from the front wall, each of the four side walls defining a portion of a respective side surface of the wearable electronic device. The wearable electronic device may further include a sensor cover covering the hole and defining a second portion of the rear exterior surface of the wearable electronic device, a display within the housing, and a biometric sensor system within the housing and configured to detect a biological parameter of a user. 
     The biometric sensor system may include an optical emitter configured to emit light through a first transparent portion of the sensor cover, and an optical sensor configured to detect, through a second transparent portion of the sensor cover, a portion of the light that is reflected by a portion of the user&#39;s body. The sensor cover may include a monolithic structure formed from a transparent material, a masked region defining an opaque region of the sensor cover, a first unmasked region defining the first transparent portion of the sensor cover, and a second unmasked region defining the second transparent portion of the sensor cover. 
     The wearable electronic device may further include an electrode coupled to the sensor cover and defining a third portion of the rear exterior surface of the wearable electronic device. The electrode may be a first electrode configured to measure a first voltage, the wearable electronic device may further include a second electrode along an exterior surface of the wearable electronic device and configured to measure a second voltage, and the wearable electronic device may be configured to determine an electrocardiogram using the first voltage and the second voltage. The second electrode may be positioned along one of the side walls of the four side walls. 
    
    
     
       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: 
         FIGS.  1 A- 1 C  depict an example electronic device; 
         FIG.  2    depicts an exploded view of the electronic device of  FIGS.  1 A- 1 C ; 
         FIGS.  3 A- 3 B  depict partial cross-sectional views of example electronic devices; 
         FIGS.  4 A- 4 B  depict partial cross-sectional views of example electronic devices; 
         FIGS.  4 C- 4 D  depict perspective views of the electronic device of  FIG.  4 A ; 
         FIG.  5 A  depicts a partial cross-sectional view of another example electronic device; 
         FIG.  5 B  depicts a rear perspective view of the electronic device of  FIG.  5 A ; 
         FIG.  5 C  depicts a partial cross-sectional view of the electronic device of  FIG.  5 A ; 
         FIGS.  6 A- 6 C  depict another example electronic device; 
         FIG.  6 D  depicts a perspective view of the electronic device of  FIGS.  6 A- 6 C ; 
         FIG.  7 A  depicts a perspective view of a chassis for an electronic device; 
         FIG.  7 B  depicts a partial cross-sectional view of a chassis and a shell for an electronic device; 
         FIGS.  8 A- 8 D  depict partial cross-sectional views of example electronic devices; 
         FIGS.  9 A- 9 B  depict an example housing for an electronic device; 
         FIGS.  10 A- 10 C  depict another example housing for an electronic device; and 
         FIG.  11    depicts a schematic diagram of an example 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 electronic watches having housings that include glass shells that define multiple sides of the devices. Conventionally, glass has been used in such devices to provide a transparent window over a touchscreen on a front of the device. Described herein, however, are electronic devices with housings that use glass to define front surfaces as well as multiple side exterior surfaces of the housing. For example, a housing for an electronic watch, also referred to as a smartwatch, may include a glass shell that resembles a five-sided box that fits onto (and is coupled to) a chassis or frame member. The glass shell may have a front glass wall that defines a front surface of the watch, as well as multiple side walls, each extending away from the front wall and each respective side wall defining at least part of a respective side surface of the housing. This configuration allows a significant amount of mechanical overlap between the chassis and the glass shell, and thus may increase the strength of the mechanical coupling between the glass shell and the chassis. Further, by forming the side walls of the watch entirely or substantially entirely out of glass, additional functional and aesthetic benefits are realized. For example, displays may be positioned adjacent the side walls to display graphical outputs on (or through) the side walls. Sensors, such as touch sensors, biometric sensors, etc., may leverage the transparent and/or dielectric properties of the glass side walls to sense or detect inputs applied to the side walls. 
     The configuration of the side walls of the glass shell also result in the seams or joints between the glass structure and the chassis being positioned further towards the rear of the watch (as compared to conventional watch configurations), away from the user-facing surfaces. This may result in a less distracting, more attractive aesthetic appearance, as there may be fewer distracting seams or other discontinuities between housing components. The glass shell may also improve the water resistance of the watch, as the seams between housing components, where water or other liquids may accumulate, may be positioned further away from the source of the liquid (e.g., rain, sweat, splashes, etc., that may primarily or initially contact the front surface of a watch). 
       FIGS.  1 A- 1 B  depict an example wearable electronic device  100 . While the instant figures illustrate the wearable electronic device  100  as an electronic watch, this is merely one example embodiment of an electronic device that uses the concepts discussed herein, and the concepts, structures, principles, and techniques described herein may apply equally or by analogy to other electronic devices, including mobile phones, tablet computers, fitness trackers, GPS devices, notebook computers, digital media players (e.g., mp3 players), or other handheld devices, wearable devices, and/or other electronic devices. 
     The wearable electronic device  100  (also referred to herein as a watch  100 ) includes a housing  102  and a band  108  coupled to the housing  102 . The band  108  may be configured to attach the watch  100  to a user, such as to the user&#39;s arm or wrist. 
     The housing  102  may at least partially define an internal volume in which components of the watch  100  may be positioned. The housing  102  may also define one or more exterior surfaces of the electronic device, such as all or a portion of one or more side surfaces, a rear surface, a front surface, and the like. The housing  102  may have a generally rectangular shape, when viewed from the front. In such cases, the housing  102  may have four sides and/or side surfaces, and four corners. In some cases, the four sides include a first pair of equal-length sides, and a second pair of equal-length sides that are shorter than the first pair of equal-length sides. Other shapes are also contemplated, such as generally square shapes (where all of the sides are substantially the same length). 
     The housing  102  may include a shell  104  coupled to a chassis  106 . The chassis  106  may be formed of metal (e.g., aluminum, steel, titanium, magnesium, a metal alloy, etc.), or another suitable material such as a polymer, a ceramic, glass, or the like. As described herein, the shell  104  may define multiple walls and multiple exterior surfaces of the housing  102 . For example, the shell  104  may define a front wall that defines a front exterior surface of the watch  100 , and multiple (e.g., four) respective side walls that each extend rearward from the front wall to define at least a portion of respective side exterior surfaces of the watch  100 . The side walls of the shell  104  may define flat side surfaces, as shown in  FIGS.  1 A- 1 C , or they may be curved, rounded, semi-circular, or any other suitable shape. The transition between the side walls and the top or front wall of the shell  104  (e.g., where the side wall meets a front wall) may be sharp (e.g., defining a distinct apex or edge), curved, chamfered, rounded, or the like. 
     The front surface of the shell  104  may define all or substantially all of the front surface of the housing  102  (and thus the watch). In such cases, the shell  104  is continuous along the front surface, and does not have a hole or other allowance for a separate display cover. In other examples, the front of the shell  104  defines a hole, and a separate display cover is positioned in the hole and attached to the shell  104  or another structure of the device  100 . In cases where the front surface of the shell  104  is continuous, the border of the display  114  shown in  FIG.  1 A  does not correspond to a seam or opening in the shell  104 , but instead represents the border of the display  114 , a mask that defines a viewable area of the display (e.g., an output region  117 ), or the like. In cases where the shell  104  defines an opening in which a display cover is positioned, the border of the display  114  as shown in  FIG.  1 A  may represent a seam between the display cover and the shell  104 . 
     The shell  104  may also define one or more through holes to allow components such as speakers, microphones, barometric sensors, vents, or other components to have access to the external environment. For example,  FIGS.  1 A- 1 C  illustrate an example location of a through hole  121 . The through hole may be positioned in a side wall of the shell  104 , as shown. Other through holes may be positioned elsewhere on the shell  104 , such as through a different side wall or the front wall. 
     The shell  104  may be formed from glass, and may be referred to as a glass shell. Where the shell  104  is formed from glass, it may be formed from any suitable glass, and may be strengthened, tempered, or processed in any other suitable way to provide a target strength, toughness, scratch resistance, appearance, or other property. Example glass compositions may include, without limitation, soda lime glass, aluminosilicate glass, borosilicate glass, glass ceramic, or the like. The glass material may be chemically strengthened (e.g., via ion exchange baths or other techniques), annealed, tempered, or processed using other techniques. The shell  104  may also include one or more coatings, such as oleophobic coatings, anti-reflective coatings, anti-scratch coatings, or any other suitable coatings, films, layers, or the like. 
     The shell  104 , or glass shell, may be formed using any suitable technique. For example, the shell  104  may be machined from a single block of glass. As another example, the shell  104  may be formed by slumping and/or molding a sheet of glass. As yet another example, the shell  104  may be formed by attaching multiple pieces of glass together. In the latter example, four glass side walls may be attached to a glass front wall, or two glass side walls may be attached to a glass structure that itself defines a front wall and two side walls. Glass pieces may be attached together using fusion bonding techniques (e.g., softening or melting portions of the glass members and joining them so that they fuse together), adhesives, or any other suitable technique. 
     In other cases, the shell  104  may be formed from materials other than glass, such as ceramics, glass ceramics, sapphire, polymers, composites, laminates, or the like. The material for the shell  104  may be optically transparent to facilitate the visibility of displays inside the device. The material for the shell  104  may also be a dielectric material or other material that facilitates the transmission and/or receipt of wireless signals into and/or out of the device. For example, the material may be selected so as to not significantly attenuate wireless signals to and/or from antennas inside the device. 
     The chassis  106  may define at least a portion of a rear exterior surface of the watch  100 , and may also define a portion of one or more side exterior surfaces of the watch  100 . The chassis  106  may also define band engagement features  119 . The band engagement features  119  may facilitate the attachment of the watch band  108  to the housing  102 . As shown, the band engagement features  119  include slots that receive end portions of the band  108 , though other types of band engagement features  119  are also contemplated. For example, the band engagement features  119  may be lugs (e.g., protruding features with holes for accepting spring bars), holes (e.g., threaded holes), bars (e.g., about which bands may be wrapped), or other suitable band engagement features. While the housing  102  is largely defined by the shell  104 , a non-glass chassis  106  may have a relatively greater strength and/or resistance to breaking than the shell  104 . Accordingly, configuring the chassis  106  to include the band engagement features (or at least to define a load-bearing portion of the band engagement features) may result in a robust and secure band attachment while maintaining the functional and aesthetic benefits of the shell  104 . 
     The shell  104  may cover (e.g., overlie) at least part of a display  114  that is positioned at least partially within the internal volume of the housing  102 . The display  114  may define or correspond to an output region  117  in which graphical outputs are displayed. Graphical outputs may include graphical user interfaces, user interface elements (e.g., buttons, sliders, etc.), text, lists, photographs, videos, or the like. The display  114  may include a liquid crystal display (LCD), an organic light emitting diode display (OLED), or any other suitable components or display technologies. The display  114  may also include or be associated with touch and/or force sensing components, as described herein. 
     The shell  104  may include a mask along a mask region  115 . The mask region  115  may form a border around and/or define the output region  117 . The mask may be an opaque material (e.g., one or more layers of ink, dye, film, etc.) that is attached to an inner surface of the shell  104 . The mask may visually occlude internal components of the watch  100 . In some cases, the mask is configured to have an appearance (e.g., color, apparent texture, etc.) that is similar to the appearance of the display  114  when the display  114  is inactive. In this way, the border between the display  114  and the mask may be visually indistinguishable to the naked eye (at a certain distance, such as 1 foot, 2 feet, 3 feet, or the like). 
     The display  114  may include or be associated with touch sensors and/or force sensors that extend along the output region of the display and which may use any suitable sensing elements and/or sensing systems and/or techniques. Using touch sensors, the watch  100  may detect touch inputs applied to the shell  104 , including detecting locations of touch inputs, motions of touch inputs (e.g., the speed, direction, or other parameters of a gesture applied to the shell  104 ), or the like. Using force sensors, the watch  100  may detect amounts or magnitudes of force associated with touch events applied to the shell  104 . The touch and/or force sensors may detect various types of user inputs to control or modify the operation of the device, including taps, swipes, multi-finger inputs, single- or multi-finger touch gestures, presses, and the like. Further, as described herein, the touch and/or force sensors may detect motion of an object (e.g., a user&#39;s finger) as it is interacting with a crown  110  of the watch  100 . 
     The watch  100  may also be configured to produce haptic (e.g., tactile) outputs that are detectable by a wearer or user of the watch  100 . The watch  100  may produce haptic outputs in various ways. For example, the watch  100  may include a movable mass that moves (e.g., oscillates or vibrates translationally and/or rotationally, or otherwise moves to produce a tactile output), which may be detectable by a user when the user is wearing or otherwise contacting (e.g., touching) the watch  100 . Haptic outputs may be produced in response to the watch  100  detecting an input or other user interaction, such as a touch input, a force input, a crown rotation, translation, or other interaction, a button press, or the like. 
     The watch  100  also includes a crown  110  (also referred to herein as a crown assembly) having a knob, external portion, or component(s) or feature(s) positioned along a side wall of the housing  102 . At least a portion of the crown  110  (e.g., a knob) may protrude from the housing  102 , and may define a generally circular shape or a circular exterior surface. The exterior surface of the crown  110  (or a portion thereof) may be textured, knurled, grooved, or may otherwise have features that may improve the tactile feel of the crown  110  and/or facilitate rotation sensing. 
     The crown  110  may facilitate a variety of potential user interactions. For example, the crown  110  may be rotated by a user (e.g., the crown may receive rotational inputs). Rotational inputs to the crown  110  may zoom, scroll, rotate, or otherwise manipulate a user interface or other object displayed on the display  114  (among other possible functions). The crown  110  may also be translated or pressed (e.g., axially) by the user. Translational or axial inputs may select highlighted objects or icons, cause a user interface to return to a previous menu or display, or activate or deactivate functions (among other possible functions). In some cases, instead of a crown that is rotatable and translatable by a user, the crown may be configured not to rotate or translate relative to the housing  102 , but may nevertheless be configured to detect user interactions that are similar to rotational and translational inputs. For example, the watch  100  may sense, using touch sensors, force sensors, optical sensors, or the like, touch inputs or gestures applied to the crown  110 . Such inputs may include a finger sliding along a surface of the crown  110 , and a finger touching (or pressing on) an end face of the crown  110 . In such cases, sliding gestures may cause operations similar to the rotational inputs, and touches (or presses) on an end face may cause operations similar to the translational inputs. As used herein, rotational inputs may include both rotational movements of the crown (e.g., where the crown is free to rotate), as well as sliding inputs that are produced when a user slides a finger or object along the surface of a crown in a manner that resembles a rotation (e.g., where the crown is fixed and/or does not freely rotate). In some cases, as noted above, haptic outputs may be produced in response to the detection of certain types of inputs applied to the crown  110 . For example, a haptic output may be produced in response to detection of a particular rotational input (e.g., a partial rotation, such as 10° rotation, 20° rotation, 30° rotation, or any other suitable rotation), a translational input, or the like. In the case of crowns that are configured not to rotate or translate relative to a housing, a haptic output may be produced in response to detection of a sliding input applied to a surface of the crown, a touch input on an axial end of the crown, or a force (applied to the axial end of the crown) that satisfies a condition (e.g., exceeds a predetermined force corresponding to an actuation threshold). 
     The crown  110  may also include or define an electrode. For example, the crown  110  may be formed from or include a conductive material (e.g., a metal), which may in turn be conductively coupled to a biometric sensing system of the watch  100 , such as an electrocardiograph sensing system. The electrocardiograph sensing system may use voltages detected by the electrode on the crown (as well as other electrodes of the watch  100 , such as the electrodes  122  in  FIG.  1 B ) to determine an electrocardiogram of the wearer. For example, the user may touch the electrode portion of the crown  110  to allow the electrode portion of the crown  110  to detect a voltage via the wearer&#39;s skin. 
     In some cases, instead of or in addition to an electrode integrated with the crown  110 , an electrode may be positioned on a surface of the shell  104 . For example, a conductive material (e.g., a metal, indium tin oxide, conductive nanowire coating, etc.) may be positioned on a side surface defined by a side wall of the shell  104 , and a user may contact the conductive material (e.g., with a finger or another body part) to facilitate the detection and/or measurement of a voltage via the conductive material. Electrodes may also or instead be positioned on a front surface defined by a front wall of the shell  104 . Electrodes mounted to a surface of the shell  104  may be coupled to the shell  104  in any suitable way and/or using any suitable technique. For example, the electrodes may be formed by plating or otherwise depositing a conductive material (e.g., a metal) onto a surface of the shell  104  (e.g., using chemical vapor deposition, plasma vapor deposition, electroless plating, or the like). As another example, a metal foil or other conductive film may be secured to the surface of the shell  104  using an adhesive or other bonding agent. An electrode that is coupled to a side wall, front wall, or other surface of a shell  104  may be coupled to a circuit within the housing (e.g., a voltage measuring circuit) in various ways. For example, a through hole may be formed through the shell  104 , and a conductor (e.g., wire, flex circuit, etc.) may extend through the hole to conductively couple the external electrode to the internal circuit. As another example, the electrode may form a continuous conductor that extends along part of the exterior surface of the shell  104 , around an edge of the shell  104 , and along part of an interior surface of the shell  104 . The portion extending along the interior surface of the shell  104  may be conductively coupled to a circuit within the device. 
     The watch  100  may also include other inputs, switches, buttons, or the like. For example, the watch  100  may include a button. The button may be a movable button (as depicted) or a touch-sensitive region of the housing  102 . The button may control various aspects of the watch  100 . For example, the button may be used to select icons, items, or other objects displayed on the display  114 , to activate or deactivate functions (e.g., to silence an alarm or alert), or the like. As noted above, a haptic output may be produced in response to detection of an input applied to the button (or indeed any other input device or system associated with the watch  100 ). Buttons may be positioned on or along a side wall of the shell  104 . For example, a button may be positioned next to the crown  110 , or on a side of the watch  100  opposite the crown  110 . In some cases, the watch includes multiple inputs, switches, buttons, or the like. 
     In cases where the watch  100  includes buttons, switches, crowns (e.g., the crown  110 ), the shell  104  may define through holes that allow components of the buttons, switches, crowns, and/or other components to pass through the shell  104  and access the interior volume of the watch  100 . For example, a shaft portion of a crown may extend through a through hole defined through a side wall of the shell  104 . The shaft portion may be coupled to one or more sensing systems within the watch  100  (e.g., rotation and/or translation sensing systems). An end or knob portion may be coupled to the shaft portion and define the component with which a user interacts (e.g., presses, rotates) to provide inputs to the watch  100  via the crown  110 . 
     As described herein, some implementations of a watch or other electronic device may include touch- and/or force-sensitive side surfaces, optionally with displays underlying the side surfaces. These functionalities may be facilitated by the transparent, dielectric properties of the material of the shell  104  (e.g., glass). Accordingly, virtual buttons, crowns, sliders, or other input regions may be displayed on the side surfaces and interacted with by a user. Other types of sensors, such as biometric sensors, imaging sensors, or the like, may be configured to detect inputs on or through the side surfaces as well. Virtual input regions and other sensors may be implemented in conjunction with or instead of physical input components such as a button and a crown  110 . 
       FIG.  1 B  depicts a rear of the watch  100 . As shown, the chassis  106  defines a portion of the side surfaces of the watch  100 , as well as a portion of the rear exterior surface of the watch  100 . The watch  100  may also include a sensor cover  116  coupled to the chassis  106 . The sensor cover  116  may cover a hole defined by the chassis  106 . In some cases, the sensor cover  116  is positioned at least partially in the hole defined by the chassis  106 . The sensor cover  116  may be configured to allow one or more sensors within the watch  100  to detect conditions external to the watch  100 . For example, the sensor cover  116  may define transparent portions, such as sensor ports  118  and emitter ports  120 . Together, the sensor ports  118  and emitter ports  120  may allow a biometric sensor system of the watch  100  to detect biometric and/or biological parameters of the wearer. For example, the sensor and emitter ports  118 ,  120  may facilitate the operation of a photoplethysmograph in which a light is emitted by an optical emitter through the emitter ports  120 , and that light may be reflected (by the wearer&#39;s body) and detected, through the sensor ports  118 , by an optical sensor. The sensor and emitter ports  118 ,  120  may be transparent portions of the sensor cover  116  (e.g., transparent to at least the particular wavelength(s) of light used by the sensor and emitter of the watch  100 ). In some cases, the sensor cover  116  may include a single piece of material (e.g., a monolithic structure) that defines both transparent portions (e.g., the sensor and emitter ports  118 ,  120 ) as well as other portions of the sensor cover  116  (e.g., non-transparent or opaque portions of the sensor cover  116  that surround the sensor and emitter ports  118 ,  120 ). The opaque portions of the sensor cover  116  may be defined by masked regions of the sensor cover  116 , and the transparent portions of the sensor cover  116  (e.g., the sensor and emitter ports) may be defined by unmasked regions of the sensor cover  116 . 
     In some cases, the sensor cover  116  may be an assembly or otherwise include multiple materials or components. For example, the sensor and emitter ports  118 ,  120  may be defined by lenses or other suitably transparent covers, windows, or other materials(s) positioned in openings in a carrier (e.g., the main structure of the sensor cover  116  that holds the sensor and emitter ports  118 ,  120 ). While  FIG.  1 B  shows two round sensor ports  118  and two round emitter ports  120 , more or fewer sensor and emitter ports  118 ,  120  may be used, and the ports may have shapes and/or positions that differ from those shown in  FIG.  1 B . 
     Other types of sensors may also or instead be integrated with the sensor cover  116 . For example, electrodes  122  may be positioned on the sensor cover  116 , and may be conductively coupled to components of a sensor system (e.g., an electrocardiograph sensing system) within the watch  100 . The electrodes  122  may be a metal or other conductive material, and may be secured or applied to the sensor cover  116  in various ways. For example, the electrodes  122  may be plated, adhered, or bonded to the sensor cover  116 , and may wrap around a side and along an interior surface of the sensor cover  116  so that the electrodes  122  may conductively couple a user&#39;s skin to a sensing system of the watch  100 . Example configurations of the electrodes  122  are described herein. The watch  100  may include two electrodes  122 , as shown, or more or fewer electrodes (e.g., one electrode, three electrodes, four electrodes, or more electrodes). 
       FIG.  1 C  is a side view of the watch  100 . As shown in  FIG.  1 C , the shell  104  defines a first portion of the side exterior surface of the housing  102 , and the chassis  106  defines a second portion of the side exterior surface of the housing. As shown, the shell  104  defines more than half of the height of the side surface, extending nearly the full distance from the front surface to the rear surface. In some cases, the side wall of the shell  104  extends about 50% of the distance from the front surface to the rear surface, about 60% of the distance from the front surface to the rear surface, about 70% of the distance from the front surface to the rear surface, about 80% of the distance from the front surface to the rear surface, about 90% of the distance from the front surface to the rear surface, or about 100% of the distance from the front surface to the rear surface. 
       FIG.  2    illustrates a partial exploded view of the watch  100  of  FIGS.  1 A- 1 C , showing the shell  104  removed from the chassis  106 . The shell  104  defines a front wall  201  (also referred to herein as a top wall) that defines a front surface of the watch  100 . The front wall  201  may also define a touch- and/or force-sensitive input surface of the watch  100 , with which a user may interact to control operations of the watch  100 . 
     The shell  104  further defines a first pair of side walls  202  (e.g., a side wall  202 - 1  and an opposite side wall  202 - 2 ) that extend rearward from the front wall  201 , and a second pair of side walls  204  (e.g., a side wall  204 - 1  and an opposite side wall  204 - 2 ) that extend rearward from the front wall  201 . The side walls of the second pair of side walls  204  may be longer than the side walls of the first pair of side walls  202 . For example, the first pair of side walls  202  may be shorter than the second pair of side walls  204  due to the presence of band engagement features  208  (e.g., band engagement features  208 - 1 ,  208 - 2 ) on those same sides of the watch  100 . In some examples, the side walls all have substantially the same length. 
     As shown in  FIG.  2   , the band engagement features  208  are defined by slots formed into the chassis  106 , though this is merely one example band engagement feature. In other cases, band engagement features may be or may include lugs, holes, bars, protrusions, or other structures. 
     The chassis  106  may define an internal wall  206  that extends from a rear portion of the chassis  106 . The internal wall  206  may extend around and at least partially define an internal volume  207  in which internal components of the watch  100  may be positioned. The internal wall  206  may extend towards the front of the watch  100  and may overlap the side walls  202  and  204 , and may be secured to the interior surfaces of the side walls  202 ,  204 , as described herein. 
       FIG.  2    also illustrates an example of the display  114 , which may be covered by the shell  104  and may be configured to produce graphical outputs that are visible through a front wall of the shell  104 . The display module  114  may also be configured to wrap or curve along one or more of the side walls of the shell  104  (which may be curved), and may be configured to display graphical outputs that are visible through the one or more side walls. In some cases, additional display modules may be configured to display graphical outputs that are visible through the side walls. 
       FIGS.  3 A- 3 B  are partial cross-sectional views of embodiments of the watch  100 , viewed along line A-A in  FIG.  1 A .  FIG.  3 A  shows an example configuration of the housing  102 , which may be defined at least in part by the shell  104 , the chassis  106 , and the sensor cover  116 .  FIG.  3 B  shows another example configuration of the housing  102 , which may be defined at least in part by a shell  300 , a chassis  312 , and the sensor cover  116 . The housings defined by the shells and chassis in  FIGS.  3 A- 3 B  may define an internal volume in which components such as the display  114 , a sensor module  310 , and other internal components  302  may be positioned. The internal components  302  may include components such as batteries, processors, memory, logic boards, battery charging circuitry (including wireless or inductive charging components such as inductive coils), wireless communication circuitry, antennas, or the like. 
     As shown in  FIGS.  3 A- 3 B , the side walls  204  ( FIG.  3 A ) and  318  ( FIG.  3 B ) each define a portion of a side surface of the watch  100 , and the chassis  106  ( FIG.  3 A ) and  312  ( FIG.  3 B ) define a second portion of that side surface of the watch  100 . As shown, however, the side walls each extend rearward more than half of the distance between the front surface of the watch  100  and the rear surface  303  of the watch. This may result in greater sealing as well as a more attractive appearance, as the seam between the shell and the chassis is positioned further away from the front surface of the watch  100 . 
     While  FIG.  3 A  shows flat side walls  204 , in some cases the side walls define a curved portion, such as a curve proximate the distal ends of the side walls (e.g., where the side walls  318  meet the chassis  312 , as illustrated in  FIG.  3 B ), a curve proximate the location where the front wall meets the side walls (as illustrated in  FIG.  4 B ), and/or a continuous curvature that extends from the front wall of a shell to the ends of the side walls (e.g., a combination of the curvatures shown in  FIGS.  3 B and  4 B ).  FIG.  3 B  illustrates an embodiment of the watch  100  in which a shell  300  defines a curve proximate the distal ends  309  of the side walls  318 . Thus, the outermost points  305  (e.g.,  305 - 1 ,  305 - 2 ) of the side surfaces of the watch  100  are defined by the shell  300 , and the outermost points  305  of the curved side walls may visually obscure or hide the seam (at least in some viewing configurations). 
       FIG.  3 B  illustrates an example in which the side walls  318  define a curved portion proximate the distal ends  309  of the side walls  318 , where the side walls  318  meet the chassis  312 . In some cases, a curvature is also present where the front wall  316  meets the side walls  318  (e.g. similar to the curvature shown in  FIG.  4 B ), such that a continuous curvature is defined along the side wall, extending from the front wall  316  to the distal ends  309  of the side walls  318 . In such cases, the entireties of the exterior surfaces of the side walls may be curved (e.g., such that the side walls do not define flat or planar exterior surface portions). A continuously curved side wall may define an apex at its outermost point, which may visually obscure or hide the seam between the distal ends of the side walls and the chassis, similar to the configuration shown in  FIG.  3 A . 
     As noted above, a chassis may define an internal wall (internal wall  206  in  FIG.  3 A  and internal wall  314  in  FIG.  3 B ) that may overlap the side walls of the shell (e.g., side walls  204  in  FIG.  3 A and  318    in  FIG.  3 B  (and also the side walls  202 ,  FIG.  2   ). The internal walls may extend about a perimeter of the chassis, and may be composed of multiple wall segments (e.g., four wall segments, as shown in  FIG.  2   ). The internal walls may resemble a rib or flange extending from a back wall defined by the chassis. The internal walls may be attached to the side walls of the shell in any suitable way, including adhesives, fasteners, or the like. In some cases, as shown in  FIG.  3 B , a gap may be defined between the internal wall  314  and the interior surfaces of the side walls  318 . An adhesive  304  or other bonding agent may be positioned in this gap to secure the shell  300  to the chassis  312 . 
     With reference to  FIG.  3 B , the adhesive  304  may form an adhesive bond with the side walls  318  and the internal wall  314 , thereby retaining the shell  300  to the chassis  312 . As used herein, adhesive bonds may refer to bonds formed as a result of chemical bonds, intermolecular forces (e.g., van der Waals forces), mechanical bonds (e.g., adhesive engaging with pores, textures, or other surface irregularities of the materials), electrostatic forces, and/or any other suitable adhesion mechanism. 
     In some cases, the shape of the interior surfaces of the side walls  318  may facilitate a mechanical interlock between the shell  300  and the chassis  312 . For example, the curvature of the side walls  318  may define convex exterior surfaces and corresponding concave interior surfaces of the shell  300 . The concave interior surfaces may define features that mechanically interlock with the adhesive  304  to retain the shell  300  to the chassis  312  and/or prevent the removal of the shell  300  from the chassis  312 . More particularly, the distal ends  309  of the side walls  318  are further towards the center of the device than the outermost points  305  of the side walls  318 . As such, when the adhesive  304  is hardened (e.g., cured, solidified, etc.), the distal ends  309  of the side walls  318  are mechanically interlocked with an undercut region of the adhesive  304 , thereby inhibiting separation of the shell  300  from the chassis  312 . 
     The shells  104 ,  300  may have a substantially uniform thickness. For example, a thickness of the side walls of a shell (e.g., side walls  202 ,  204 ,  318 ) may have substantially the same thickness as the front wall of the shell. The shell may have a thickness between about 1.5 mm and about 0.5 mm. In some cases, the thickness may be about 1.5 mm, about 1.25 mm, about 1.0 mm, about 0.75 mm, about 0.5 mm, or any other suitable thickness. In some cases, different portions of the shell may be thicker than others. For example, the distal ends of the shell (e.g., the free ends of the side walls), and/or the curved portions of the side walls, may be thicker than other portions of the shell. 
     While  FIGS.  3 A- 3 B  illustrate physical engagement between a chassis and one pair of side walls (e.g., side walls  204 ,  318 ), it will be understood that the side walls  202 , or any other side walls of a shell as described herein, may have the same or similar configuration as the side walls shown in  FIGS.  3 A- 3 B , and may use the same or similar structures and techniques to physically engage a shell with a chassis. 
     As described above, the watch  100  may include a display  114 . The display  114  may be coupled to an interior surface of the front wall of the shell (e.g., front wall  201  in  FIG.  3 A  or front wall  316  in  FIG.  3 B ), or may otherwise be positioned within the housing of the watch  100  such that it can produce graphical outputs that are visible through the front wall. In order to define a boundary of an active area of the display  114  and/or prevent the visibility of internal components of the watch  100 , an opaque mask  306  may be positioned along a front interior surface of the shell (as shown in  FIGS.  3 A and  3 B ). In some cases, the opaque mask  306  is positioned along all of the internal surface of the shell except the active display area (e.g., such that the opaque mask  306  defines an opaque boundary around a transparent portion of the shell through which the display is viewed). In some cases, the opaque mask  306  may be omitted from certain areas of the internal surface. For example, in cases where a display, sensor, or other component may require transparency or translucency, the opaque mask may be omitted from that particular area. The opaque mask  306  may be one or more layers of ink, dye, film, deposition layer (e.g., a layer of material deposited by a vapor or other deposition technique), coating, or the like. 
     As shown in  FIGS.  3 A- 3 B , the watch  100  also includes one or more sensors, represented by a sensor module  310 . The sensor module  310  may not represent the exact size, location, or configuration of the sensors in the watch  100 , but is intended more as a schematic illustration of the sensors. In some cases, the sensor module  310  may include sensing systems (or components thereof) such as a photopletheysmograph, an electrocardiograph, a pulse oximeter, or other biometric or other sensing systems. Biometric sensing systems may be configured to detect and/or measure biological parameters of a wearer. Such sensing systems may include components such as voltage sensors, optical emitters, optical sensors, cameras, or any other suitable components to facilitate biometric or other sensing. The sensing systems of the watch  100  may access or otherwise interact with the outside environment via the sensor cover  116 , which may be positioned in an opening  307  in the chassis. 
     The sensor cover  116  may be formed from a transparent material such as glass, ceramic, sapphire, metal, polymer, a composite (e.g., fiber-reinforced polymer), or the like. In some cases, the sensor cover  116  may be formed from an opaque material and may define openings in which transparent materials or components are positioned, as described herein. 
     As noted above, the sensor cover  116  may define transparent portions, such as sensor ports  118  and emitter ports  120  ( FIG.  1 B ).  FIGS.  3 A and  3 B  illustrate one example configuration of the sensor cover  116  in which the sensor ports  118  are defined by transparent or translucent materials positioned in openings in a carrier member  311 . The carrier member  311  may be formed of an opaque material, or it may be formed of a transparent material and include a mask (e.g., dye, ink, film, etc.) to produce an opaque appearance. 
     In other cases, instead of separate materials or components positioned in openings in the carrier member  311 , the sensor ports  118  may be defined by transparent portions of a monolithic carrier member  311 . In such cases, the carrier member  311  may be formed of a transparent material and may include a mask (e.g., dye, ink, film, etc.) to define opaque regions in areas other than the sensor ports  118  (e.g., surrounding the sensor ports  118 ). While  FIGS.  3 A- 3 B  illustrate example configurations of the sensor ports  118 , the same and/or similar configurations may apply to the emitter ports  120  as well. A sensor cover  116  may also use inset transparent materials to provide optical access for some sensor components, and use monolithic transparent regions of a carrier to provide optical access for other sensor components. 
     As noted above, electrodes  122  may be positioned on the sensor cover  116 , and may be conductively coupled to an electrocardiograph sensing system (represented by the sensor module  310 ). The electrodes  122  may be a metal or other conductive material. The electrodes  122  may wrap around an edge of the sensor cover  116  to define an exterior portion and an interior portion of each electrode. The exterior portion may define part of the rear surface of the watch  100  and may be positioned so that it is likely to be in contact with a user when the watch  100  is being worn. The interior portion of an electrode may be conductively coupled to a voltage sensor or other component or system, and a voltage measurement from the electrode (optionally along with voltage measurements from other electrodes on the sensor cover  116 , the crown  110 , and/or elsewhere on the device) may be used by an electrocardiograph to determine an electrocardiogram of the wearer. 
       FIG.  4 A  depicts an example cross section of a watch  400 , which may be an embodiment of the watch  100 . The description of the various components and elements of the watch  100  may also be applicable to the watch  400  depicted in  FIG.  4 A . A redundant description of some of the components is not repeated herein for clarity. 
     Whereas the watch  100  includes a display that is viewable through the front wall  404  of the shell, the watch  400  includes a display  402  that is viewable through the front wall  404  of a shell  401  (which may be the same as or similar to the shell  104 ) as well as through the side walls  406  of the shell  401 . For example, the display  402  may define a first portion  418  that is adjacent the front wall  404  of the shell  401  (or otherwise viewable through the front wall), as well as second portions  420  that are adjacent the side walls  406  of the shell  401  (or otherwise viewable through the side walls). The display  402  may be a single display component that is bent, flexed, or otherwise formed to the contour of the interior surfaces of the shell  401 . In other cases, the display  402  may include separate display components. For example, one physical display stackup may be used to display graphical outputs through the front wall  404  of the shell  401 , while a separate physical display stackup may be used to display graphical outputs through the side wall  406 - 1 , and yet another separate physical display stackup may be used to display graphical outputs through the side wall  406 - 2 . The boundary between the physical display stackups may be at the line  416 , though this is merely one example. In some cases, the stackup that is vieweable through the front wall  404  is substantially planar, and the stackups that are viewable through a side wall are non-planar (e.g., curved). In cases where a single display stackup is used to display graphical outputs through both the front wall and one or more side walls, the lines  416  may represent a functional boundary between “front facing” and “side facing” display regions. Further, while the watch  400  shows displays adjacent two side walls, this is merely one embodiment, and a watch as described herein may have displays that can display graphical outputs on one, two, three, or four side walls of the device. 
     The watch  400  may also include a mask  410  along some portions of the interior surface of the shell  401 . For example, the mask  410  may be positioned along a portion of the shell  401  that is in contact with an adhesive  414  (where the adhesive  414  attaches the shell  401  to a chassis  408 , in a manner similar to the adhesive  304 ,  FIG.  3 B ). The mask  410  may also be positioned along other portions of the shell  401 , such as to mask or occlude boundaries between different display stackups (e.g., to cover a gap between components at line  416 ). The mask  410  may be an opaque material (e.g., one or more layers of ink, dye, film, etc.) that is attached to an inner surface of the shell  401 . 
       FIG.  4 B  illustrates another example of the watch  400 , in which a shell  431  defines a curved surface where the side walls  432  meet the front wall  433 . The curved surface may have a corresponding curved (e.g., concave) interior surface, that a display  434  may be proximate or attached to. In some cases, the display  434  is adhered to the interior surface of the shell  431 , including along an interior surface of the front wall  433 , the interior surface of the side walls  432 , and the interior concave surface between (and joining) the front wall  433  and the side walls  432 . As the side walls  432  in  FIG.  4 B  do not define a curve at their distal ends, the side walls  432  may define flanges  435 , which may engage an adhesive  436  (in a manner similar to the sidewalls  406  and adhesive  414  in  FIG.  4 A ) to retain the shell  431  to the chassis  408 . 
       FIGS.  4 C- 4 D  illustrate the watch  400  of  FIG.  4 A  with graphical outputs displayed through a side wall by a side-facing portion of the display  402  (e.g., a second portion  420 - 1  of the display  402 ). Notably, the display  402  can produce various types of graphical outputs on the sides of the device, and can dynamically change or vary the graphical outputs based on factors such as time of day, an active application of the watch  400 , a current activity of the wearer (e.g., exercise, listening to music, watching video media, sleeping, working, running, swimming, etc.), or any other suitable factor. Further, the watch  400  may include touch sensing systems, force sensing systems, or other types of sensing systems that can detect inputs applied to the front and/or side walls of the watch  400  (e.g., touch inputs applied by a user). Accordingly, the graphical outputs displayed on the sides of the watch  400  may be buttons, sliders, or other affordances. 
       FIG.  4 C , for example, illustrates the watch  400  while displaying a first set of graphical outputs on a side display region  425  of the watch  400 . For example, the graphical outputs may include buttons  422 ,  424 , and  426 , where the buttons  424 ,  426  are configured as directional buttons (e.g., arrows). The buttons  422 ,  424 ,  426  may be used to navigate within a graphical user interface that is displayed on a front display region  423  of the watch  400  (e.g., to move a cursor or other “active” element indicator with the directional buttons, and select particular affordances, functions, or other elements with the button  422 ). The directional buttons  424 ,  426  may control functions such as volume (e.g., of a speaker of the watch  400  or of other devices that may be controlled by the watch such as a phone, headphones, a tablet computer, a wireless speaker unit, or the like). 
       FIG.  4 D  illustrates the watch  400  while displaying a second set of graphical outputs on the side display region  425  of the watch  400 . For example, the graphical outputs in  FIG.  4 D  may include a start button  428  and a stop button  430 . The watch  400  may transition from the first set of graphical outputs (e.g., those shown in  FIG.  4 C  or any other graphical outputs or even a blank side display region) to the second set of graphical outputs upon activation of an application, detection of an activity of the wearer, or the like. For example, the start and stop buttons  428 ,  430  may control a stop watch or other fitness tracker, or it may control music or other media playback. 
     The buttons shown in  FIGS.  4 C- 4 D  are merely examples of buttons, affordances, images, or other graphical outputs that may be displayed on a side display region of a watch  400 . Other types of graphical outputs may be displayed on a side display region of a watch depending on user settings, detected conditions of the watch and/or of the user, or based on other factors or triggering events. 
     In some cases, other types of sensing systems may be integrated with or otherwise use the side walls of a watch as input surfaces. For example, a fingerprint sensor may be positioned within the watch  400  adjacent a side wall of the shell  401 . A user may place a finger on the side wall in the region of the fingerprint sensor (which may be graphically indicated by a graphical output of a display, a marking on the shell  401 , or the like), and the fingerprint sensor may capture an image or other representation of a user&#39;s fingerprint to authenticate the user and, optionally, unlock the watch  400  and/or other devices with which the watch  400  can communicate. In some cases, cameras, optical sensors, photoplethysmographs, blood oxygen sensors, ambient light sensors, depth sensors, or the like, may be positioned within the watch  400  and may be configured to access the external environment using the transparency of the shell  401  (including the side walls of the shell  401 ). 
     In some cases, a watch may include a glass (or other transparent dielectric material) shell that defines a front surface and at least a portion of the side surfaces of the watch, similar to those described with respect to  FIGS.  1 A- 4 D , as well as a glass (or other transparent dielectric material) component that defines a rear surface and another portion of the side surfaces of the watch.  FIGS.  5 A- 5 C  illustrate an example watch  500  that includes a first shell  502  (e.g., a first glass shell) that defines a top or front surface  504  of the watch  500 , as well as a first portion of the side surfaces  506  of the watch  500 , and a second shell  508  (e.g., a second glass shell) that defines a portion of a rear surface  510  as well as a second portion of the side surfaces  506 . 
     The second shell  508  may be attached to the first shell  502  via an adhesive  520 , which may be the same as or similar in materials, function, etc., to the adhesives described elsewhere herein (e.g., the adhesive  304 ,  FIG.  3 B ). The first shell  502  and the second shell  508  may include masks  522 ,  523  (respectively), which may be positioned along an interior surface of the first and second shells  502 ,  508  (e.g., along a portion of the front interior surface and side interior surfaces (which may have concave curvatures) of the first shell  502 , and along a portion of a back interior surface). In some cases, the masks are opaque and mask, cover, or occlude internal components. Openings in the masks (or areas where the mask is not applied) may define display regions or other windows, openings, or transparent regions for displays, sensors, or other components or functions. The masks  522 ,  523  may be an opaque material (e.g., one or more layers of ink, dye, film, etc.) that is attached to an inner surface of the shells. 
     The watch  500  may also include a frame  512  within the watch  500 . The frame  512  may act as a chassis or main structural component of the watch  500  to which other components may be coupled. For example, the second shell  508  may be secured to the frame  512  (e.g., via fasteners, adhesives, mechanical interlocks, or any other suitable attachment technique). Other components may also be coupled to the frame  512  (e.g., logic boards, processors, batteries, sensor modules, displays, memory, battery charging circuitry, etc.). The frame  512  may be formed of metal (e.g., aluminum, steel, an alloy, etc.), a polymer, a composite, or any other suitable material. 
     The second shell  508  may also define a sensor cover  514 . The sensor cover  514  may be configured to allow one or more sensors within the watch  500  to detect conditions external to the watch  500 . For example, the sensor cover  514  may define transparent portions, such as sensor ports  525  and emitter ports  527  ( FIG.  5 B ) which may be the same as or similar to the sensor and emitter ports  118 ,  120  described herein. A redundant description of some of the components is not repeated herein for clarity. The sensor cover  514  may protrude outwardly from the rear of the watch so that it can press against the skin on the wrist of a user, which may help facilitate positive contact between the sensor cover  514  and the user&#39;s skin, thereby improving the effectiveness of biometric sensors of the watch. 
     Similar to other watches described herein, electrodes  516  may be positioned on the sensor cover  514 , and may be conductively coupled to components of a sensor system (e.g., an electrocardiograph sensing system) within the watch  500 . The electrodes  516  may be a metal or other conductive material, and may be secured or applied to the sensor cover  514  in various ways. For example, the electrodes  516  may be plated, adhered, or bonded to the sensor cover  514 , and may extend through holes  518  formed through the sensor cover  514  (or formed through the second shell  508  more generally) so that the electrodes  516  may conductively couple a user&#39;s skin to a sensing system of the watch  500 . The watch  500  may include two electrodes  516 , as shown, or more or fewer electrodes (e.g., one electrode, three electrodes, four electrodes, or more electrodes). 
     In some cases, as shown in  FIG.  5 A , a sensor cover  514  may protrude somewhat from a surrounding region of the rear surface  510 . The protrusion of the sensor cover  514  may be formed by a region of the second shell  508  that has an increased thickness relative to a region of the second shell  508  that surrounds or is adjacent the sensor cover  514 . For example in the case of a glass second shell  508 , the increased thickness may be formed by forming a single monolithic piece of glass such that the piece of glass defines the increased thickness region, or it may be formed by applying one or more additional layers of glass to the second glass shell  508 .  FIG.  5 A  illustrates an example location of a seam or boundary  524  where an additional layer of glass (or other suitable material) has been applied to a main portion of the second shell  508  to define the increased thickness region of the sensor cover  514 . The layer of glass may be attached to the main portion of the second shell  508  in any suitable way, such as with an adhesive, by direct fusion of the layer to the main portion (e.g., via heat and pressure applied to the layer and the main portion), laser welding, or by any other suitable technique. In other cases, the protrusion may be formed by a curved region formed in a region of the second shell  508  that otherwise has a substantially uniform thickness (e.g., such that a concave recess is defined along the interior surface and a convex bump is defined along the exterior surface of the second shell  508 ). 
       FIG.  5 B  shows a rear perspective view of the watch  500 . As shown in  FIG.  5 B , the rear surface  510  of the watch may be a substantially continuous piece of glass (with the exception of the electrodes  516 , if equipped, and the lenses, windows, or other inset members for emitter and receiver ports, if equipped).  FIG.  5 B  also illustrates a watch band  529  attached to the watch housing via watch band engagement features, as described in greater detail with respect to  FIG.  5 C . 
       FIG.  5 C  is a partial cross-sectional view of the watch  500 , viewed along a line similar to line B-B in  FIG.  1 A .  FIG.  5 C  illustrates one example configuration in which watch band engagement features are defined by the frame  512 . For example, the frame  512  may define structural segments  530  that extend through an opening  531  in the first shell  502  (and/or the second shell  508 , depending on the particular structural configuration of the shells). The structural segments  530  may define watch band engagement features  532  to which the watch band  529  ( FIG.  5 B ) may be coupled. As shown, the watch band engagement features  532  include slots that receive an end of the watch band  529 , though this is merely one example embodiment. In other cases, the watch band engagement features  532  may be bars, fasteners, threaded holes, lugs, or any other suitable structure for coupling a watch band to the watch  500 . One potential advantage of the configuration shown in  FIG.  5 C  is that any loads from the watch band  529  are directly coupled to an internal structural component (e.g., the frame  512 ), rather than the shells  502 ,  508 . This may facilitate the use of thinner material (e.g., glass) for the shells, or otherwise help prevent or reduce damage to the shells. 
     In some cases, band engagement features may be coupled directly to a shell.  FIGS.  6 A- 6 D  illustrate an example watch  600  in which band engagement features (specifically, lugs) may be attached directly to an exterior surface of a shell that defines a top and side surfaces of the watch  600 . 
       FIG.  6 A , for example, shows a portion of a watch  600  with the shell  602  separated from a chassis  604 . The shell  602  may define a top or front wall, and four side walls, and the chassis  604  may define an internal wall that overlaps the side walls and is configured to be attached to the side walls of the shell  602 . Whereas some shells described herein may have side walls of different lengths, the four side walls of the shell  602  may have substantially the same lengths. More particularly, the shorter side walls of other shells described herein may be configured to accommodate a watch band engagement feature. Because the watch band engagement features of the watch  600  are attached directly to the shell  602 , the side walls of the shell  602  may all be the same or substantially the same length. Of course, side walls of different lengths may be used. 
       FIG.  6 B  shows the watch  600  with the chassis  604  and the shell  602  attached to one another, and with a set of band engagement features  606  shown separated from the shell  602 .  FIG.  6 C  shows the watch  600  with the band engagement features  606  coupled to the shell  602 .  FIG.  6 D  is a perspective view of the watch  600  with the band engagement features  606  attached to the shell  602  and a watch band  608  coupled to the watch housing via the band engagement features  606 . The watch band  608  may be coupled to the band engagement features  606  in any suitable manner. For example, the band engagement features  606  may define holes into which a spring bar (or any other suitable bar, rod, or other member) may extend to define a bar to which the band  608  may attach. The band engagement features  606  may be formed of any suitable material. For example, they may be formed from metal, metal alloys, glass, polymer, ceramic, or the like. 
     The band engagement features  606  may be attached to the shell  602  in various ways. For example, the band engagement features  606  may be attached to the shell  602  via adhesives, fasteners, fusion bonding, mechanical interlocks, or the like. In some cases, the band engagement features  606  may be formed of glass and may be attached to the shell  602  by fusing the glass of the band engagement features  606  to the glass of the shell  602 . In some cases, instead of attaching separate band engagement features  606  to the shell  602 , the band engagement features  606  may be integrally formed with the shell  602  (e.g., the shell  602  and the band engagement features  606  may be formed as a single monolithic structure). 
     In some cases, the band engagement features  606  may be secured to the chassis  604  instead of the shell  602 . In such cases, holes may be defined through the shell  602 , and the band engagement features  606  may be secured to the chassis  604  through the holes. The chassis  604  may also define holes (e.g., threaded holes), and the band engagement features  606  may be secured to the chassis  604  via fasteners (e.g., threaded fasteners) that engage the holes in the chassis  604 . Other techniques for securing the band engagement features  606  to the chassis  604  are also contemplated. 
     As described herein, a shell may be attached to a chassis via an adhesive that is positioned in a gap defined between overlapping portions of an internal wall of the chassis and side walls of the shell. Any suitable type of adhesive may be used to attach a chassis to a shell, including but not limited to thermoset adhesives, thermoplastic adhesives, epoxies, resins, or the like. 
       FIGS.  7 A- 7 B  illustrate example structures and techniques that may be used to introduce the adhesive or other bonding agent into the gap.  FIG.  7 A , for example, illustrates an example chassis  700 , which may be an embodiment of other chassis described herein (e.g., the chassis  106 ,  408 ,  604 , etc.). 
     The chassis  700  may define a rear wall  702  and a wall  704  (e.g., an internal wall, such as the internal wall  206 ) extending from the rear wall, which may define a portion of a rear surface of the watch in which the chassis  700  is used. The chassis  700  may also define a hole  706  in the rear wall  702 . The hole  706  may be adapted to receive a sensor cover, such as the sensor cover  116  described above, and may facilitate access to the external environment by sensor systems in the watch. The chassis  700  may also define an adhesive entry port  708 . The adhesive entry port  708  may be through the hole that extends through the wall  704  and communicates with the gap between the wall  704  and a side wall of a shell. As shown, the adhesive entry port  708  is formed through the wall  704 , though it may be formed through any portion of the chassis  700  that communicates with the gap. Moreover, while one adhesive entry port is shown, the chassis  700  may include additional adhesive entry ports as well to facilitate introduction of an adhesive into the gap. The chassis  700  may also include vent ports to allow air to escape the gap as adhesive is flowed into the gap. 
       FIG.  7 B  is a partial cross-sectional view of the chassis  700  and a shell  710  (as viewed along line C-C in  FIG.  1 A ), after the shell  710  and the chassis  700  are assembled so that they can be adhered together. As shown in  FIG.  7 B , a gap  714  may be defined between an interior surface of the side wall of the shell  710  and the internal wall  704  of the chassis  700 . Once the shell  710  and the chassis  700  are in a desired position relative to one another, an adhesive may be introduced into the gap  714  through the adhesive entry port  708 , as indicated by flow lines  712 . The adhesive may flow into the gap  714  and around the internal wall  704  such that it occupies at least a portion of the gap  714 . The adhesive may then be allowed to cure or harden, thereby securing the shell  710  to the chassis  700 . 
     The shell  710  and the chassis  700  may be adhered to one another before all of the internal components of the device are positioned in the internal cavity. In such case, components may be positioned in the device by passing them through the hole  706  in the rear wall  702  of the chassis  700 . 
       FIGS.  8 A- 8 D  illustrate partial cross-sectional views of shells and chassis, showing various configurations and techniques for delivering and containing the adhesive to the desired locations. The cross-sectional views in  FIGS.  8 A- 8 D  are viewed along a line similar to the line A-A in  FIG.  1 A . 
       FIG.  8 A , for example, includes a shell  800  and a chassis  802  (which may be embodiments of the shell  104  and the chassis  106 ). As described herein, the chassis defines an internal wall  803  that overlaps a side wall  805  of the shell  800 , and a gap is defined between the internal wall  803  and the interior surface of the side wall  805 . An adhesive  804  has been introduced into the gap to secure the shell  800  and the chassis  802  together, as described herein. For example, the adhesive  804 , in a flowable state, may have been introduced into the gap through a hole in the chassis  802 .  FIG.  8 A  also illustrates example engagement features  807  that may be formed on an outward-facing side of the side wall  805 . The engagement features  807  may be configured to mechanically engage and/or interlock with the adhesive  804  to help retain the adhesive  804  to the internal wall  803 , thereby contributing to the mechanical coupling between the shell  800  and the chassis  802 . The engagement features  807  are illustrated as channels extending along the internal wall  803 , though other features are also contemplated, such as holes, textures, dovetails, protrusions, bumps, recesses, dimples, posts, or the like. 
     In order to contain the adhesive  804  in the gap during the introduction of the adhesive  804 , a compliant member  806  may be positioned between and in contact with the internal wall  803  of the chassis  802  and an interior surface of the side wall  805  of the shell  800 . The compliant member  806  may be an elastomeric or deformable polymer or other material that can be compressed between the shell  800  and the chassis  802  to cause the compliant member  806  to conform to the shape of the surfaces it contacts and to form a seal therebetween. The compliant member  806  may be an o-ring, a foam that is applied to the chassis  802 , or any other suitable sealing material or component. The compliant member  806  (and any other compliant members described herein) may be formed from any suitable material, such as silicone, nitrile, rubber, Buna N, or the like. 
     The compliant member  806  may help contain the adhesive  804  in the gap between the shell  800  and the chassis  802  during introduction of the adhesive  804 . This may help ensure that the adhesive  804  fills the gap, rather than simply spilling out into the interior of the device and/or contacting a display stack  808 . The compliant member  806  may be secured to the internal wall  803  of the chassis  802  (e.g., via adhesive, self-adhesion, mechanical means, etc.) so that it is retained in position during assembly and during introduction of the adhesive  804 . The compliant member  806  may also act as an environmental seal to help inhibit the ingress of liquid or other contaminants (e.g., should there be any gaps in the adhesive  804  or if the adhesive  804  otherwise may not provide environmental sealing). 
       FIG.  8 B  illustrates another example configuration of a shell  810  and a chassis  812 . In this example, a side wall  815  of the shell  810  may not define a concave interior surface, and instead may have an increased thickness (e.g., relative to a top or front wall of the shell  810 ), and may define a substantially planar interior surface. The chassis  812  may define an internal wall  817 , and a compliant member  816  may be positioned between and in contact with the chassis  812  and the side wall  815  of the shell  810 . 
     The increased thickness of the side wall  815  may result in little or no gap between the interior surface of the side wall  815  and the internal wall of the chassis  812 . Accordingly, in some cases, little or no adhesive may be introduced in the gap, and the shell  810  may be secured to the chassis  812  using mechanical interlocks, fasteners, or other materials and/or techniques. In other cases, an adhesive, which may have a lower viscosity than other adhesives, may be introduced into the gap to secure the shell  810  to the chassis  812 . The compliant member  816 , which may otherwise be the same as or similar to the compliant member  806 , may inhibit ingress of liquids or other contaminants into the interior of the watch. The watch may also include a display stack  818 . 
       FIG.  8 C  illustrates another example configuration of a shell  820  and a chassis  822 . In this example, the internal wall  827  defines a flange portion  829 . The flange portion  829  may extend at an angle from the main portion of the internal wall  827  (e.g., the vertical portion, as oriented in  FIG.  8 C ) and may have a curve, angle, contour, or shape that is the same as or otherwise conforms to the curve, angle, contour, or shape of the side wall  825  of the shell  820 . The flange portion  829  may be positioned closer to the interior surface of the side wall  825 , thus forming an area where the gap between the side wall  825  and the internal wall  827  is reduced (relative to other areas of the gap). This may increase the effectiveness of the compliant member  826 , as the smaller gap may reduce the amount and/or pressure of the adhesive  824  on the compliant member  826  during the adhesive introduction process. This may help ensure that the adhesive  824  fills the gap, rather than simply spilling out into the interior of the device and/or contacting a display stack  828 . The flange portion  829  may also increase the strength and/or durability of the assembled device, as the flange portion  829  produces a larger contact area between the chassis  822  and the shell  820  in the event of a drop event or other impact that could force the chassis  822  and the shell  820  into contact with one another. 
       FIG.  8 D  illustrates another example configuration of a shell  830  and a chassis  832 . In this example, the seal is omitted from at least a portion of the gap between the internal wall  837  and the side wall  835 , such that adhesive  834  can flow out of the gap and into other areas of the device. For example, a channel  839  may be defined between the interior surface of the side wall  835  and the internal wall  837  of the chassis. When the adhesive  834  is introduced into the gap between the side wall  835  and the internal wall  837 , the adhesive  834  may flow through the channel  839 . As shown, the adhesive  834  flows along a rear-facing surface of a display stack  838 . The adhesive  834  may act as a sealing or potting material to help seal and/or encapsulate the display stack  838  (which may include display components, touch-sensing and/or force-sensing components, or the like). The adhesive  834  may also act as a mask that inhibits visibility of internal components of the device. 
     The thickness of the adhesive  834  along the display stack  838  (or at any other locations outside of the gap between the side wall  835  and the internal wall  837 ) may be defined by placing a removable mold surface in the internal cavity defined by the shell  830  and the chassis  832 . For example, a removable plate may be set apart from the rear-facing surface of the display stack  838 . When the adhesive  834  is introduced into the gap between the side wall  835  and the internal wall  837 , the adhesive  834  will flow into the gap, flow through the channel  839 , and flow into the space between the removable plate and the display stack  838 . Once at least partially cured and/or hardened, the removable plate may be removed. In cases where electrical components are covered and/or encapsulated by the adhesive  834 , portions of the adhesive  834  may be ablated or removed to expose the components. For example, adhesive may be removed to expose electrical contacts, connectors, circuit elements, or other features or components. In some cases, the adhesive  834  may be prevented from contacting and/or covering the electrical connectors, contacts, circuit elements, or the like, so that they can be accessed without having to remove the adhesive  834  from those areas. While  FIG.  8 D  illustrates the adhesive  834  covering at least part of the display stack  838 , the adhesive  834  may be allowed to flow against other internal components as well. In some cases, the adhesive  834  may be injected so that it occupies substantially all of the otherwise unused or empty internal space in the device. 
       FIGS.  9 A- 9 B  illustrate an example shell  902  and chassis  904  that may be used to form at least part of a housing for a watch. The shell  902  and the chassis  904  may be embodiments of the shell  104  and the chassis  106 , described above. 
       FIG.  9 A  shows the shell  902  separate from the chassis  904 . As shown, the watch band engagement features  908  are defined entirely by the chassis  904 . For example, all of the surfaces of the slots that are configured to receive the watch band are defined by the chassis  904 . Also, the watch band engagement features  908  may be formed in the chassis  904  prior to the chassis  904  being attached to the shell  902 . The shell  902  may define cutout regions  906  that engage with and/or accept a portion of the chassis  904  that forms the watch band engagement features  908 .  FIG.  9 B  is a side view of the shell  902  and the chassis  904  after being assembled. As shown in  FIG.  9 B , the shell  902  does not extend into or otherwise define any surfaces or edges of the watch band engagement features  908 . 
       FIGS.  10 A- 10 C  illustrate an example shell  1002  and chassis  1004  that may be used to form at least part of a housing for a watch. More particularly,  FIGS.  10 A- 10 C  illustrate an example configuration and manufacturing process in which watch band engagement features (e.g., slots) are formed after the shell  1002  and the chassis  1004  are assembled together, and in which a portion of the shell  1002  may define a portion of the watch band engagement features  1012 . 
       FIG.  10 A  shows the shell  1002  separate from the chassis  1004 . As shown, the chassis  1004  includes material at the locations  1006  where the watch band engagement features (e.g., watch band slots) are to be formed. Prior to forming the watch band engagement features, the shell  1002  may be attached to the chassis  1004 . Adhesive (e.g., adhesive  1010 ,  FIG.  10 B ) may be used to secure the shell  1002  to the chassis  1004 . The adhesive  1010  may be applied using the techniques described with respect to  FIGS.  7 A- 7 B , for example. 
     Once the shell  1002  is secured to the chassis  1004 , the assembly may be machined or otherwise processed to form the watch band engagement features  1012 .  FIG.  10 C , for example, illustrates the shell  1002  and chassis  1004  after the watch band engagement features  1012  have been formed. The watch band engagement features  1012  may be formed by any suitable operation or operations, such as machining, grinding, laser or other beam-based cutting operation, or the like. Operations such as lapping and/or polishing may also be performed after a first material removal operation in order to produce a desired surface finish or texture (or lack of texture) on the surfaces of the watch band engagement features  1012 . 
     In some cases, the operation of forming the watch band engagement features  1012  results in material being removed from both the shell  1002  and the chassis  1004 . This may also result in the shell  1002  defining a portion of the watch band engagement features  1012 . For example, as shown in  FIG.  10 B , an end surface  1014  of the shell  1002  may define part of a watch band slot, and a watch band, when attached to the housing via the watch band slot, may contact the end surface  1014  of the shell  1002 . In some cases, a coating or covering may be applied to the end surface  1014  of the shell  1002 . For example, a polymer coating may be applied to the end surface  1014  to prevent chipping or other damage to the shell  1002 . 
       FIG.  11    depicts an example schematic diagram of an electronic device  1100 . The electronic device  1100  may be an embodiment of or otherwise represent the watch  100  (or any other watches or device(s) described herein). The device  1100  includes one or more processing units  1101  that are configured to access a memory  1102  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 electronic devices described herein. For example, the instructions may be configured to control or coordinate the operation of one or more displays  1108 , one or more touch sensors  1103 , one or more force sensors  1105 , one or more communication channels  1104 , one or more audio input systems  1109 , one or more audio output systems  1110 , one or more positioning systems  1111 , one or more sensors  1112 , and/or one or more haptic feedback devices  1106 . 
     The processing units  1101  of  FIG.  11    may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processing units  1101  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 processing units  1101  may be coupled to a circuit board. 
     The memory  1102  can store electronic data that can be used by the device  1100 . For example, a memory can store electrical data or content such as, for example, audio and video files, images, documents and applications, device settings and user preferences, programs, instructions, timing and control signals or data for the various modules, data structures or databases, and so on. The memory  1102  can be configured as any type of memory. By way of example only, the memory 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  1103 , also referred to herein as touch-sensing systems, 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  1103  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the touch sensors  1103  may be capacitive touch sensors, resistive touch sensors, acoustic wave sensors, or the like. The touch sensors  1103  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  1103  may be integrated with or otherwise configured to detect touch inputs applied to any portion of the device  1100 . For example, the touch sensors  1103  may be configured to detect touch inputs applied to any portion of the device  1100  that includes a display (and may be integrated with a display). For example, the touch sensors  1103  may be configured to detect touch inputs applied to front and/or side surfaces of a shell. The touch sensors  1103  may operate in conjunction with the force sensors  1105  to generate signals or data in response to touch inputs. A touch sensor or force sensor that is positioned over a display or otherwise integrated with a display may be referred to herein as a touch-sensitive display, force-sensitive display, or touchscreen. 
     The force sensors  1105  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  1105  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the force sensors  1105  may be strain-based sensors, piezoelectric-based sensors, piezoresistive-based sensors, capacitive sensors, resistive sensors, or the like. The force sensors  1105  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  1105  may be used in conjunction with various input mechanisms to detect various types of inputs. For example, the force sensors  1105  may be used to detect presses or other force inputs that satisfy a force threshold (which may represent a more forceful input than is typical for a standard “touch” input). Like the touch sensors  1103 , the force sensors  1105  may be integrated with or otherwise configured to detect force inputs applied to any portion of the device  1100 . As a specific example, force sensors  1105  may be configured to detect force inputs applied to the front and/or side surfaces of a shell. The force sensors  1105  may be configured to detect force inputs applied to portions of the device  1100  that include a display (and may be integrated with the display). The force sensors  1105  may operate in conjunction with the touch sensors  1103  to generate signals or data in response to touch- and/or force-based inputs. 
     The device  1100  may also include one or more haptic feedback devices  1106  (also referred to simply as haptic devices  1106 ). The haptic device  1106  may include one or more of a variety of haptic technologies such as, but not necessarily limited to, rotational haptic devices, linear actuators, piezoelectric devices, vibration elements, and so on. In general, the haptic device  1106  may be configured to provide punctuated and distinct feedback to a user of the device. More particularly, the haptic device  1106  may be adapted to produce a knock or tap sensation and/or a vibration sensation. Such haptic outputs may be provided in response to detection of touch and/or force inputs, and may be imparted to a user through an exterior surface of the device  1100  (e.g., via front, side, and/or rear surfaces of a wearable device such as a watch). 
     The one or more communication channels  1104  may include one or more wireless interface(s) that are adapted to provide communication between the processing unit(s)  1101  and an external device. The one or more communication channels  1104  may include antennas, communications circuitry, firmware, software, or any other components or systems that facilitate wireless communications with other devices. In general, the one or more communication channels  1104  may be configured to transmit and receive data and/or signals that may be interpreted by instructions executed on the processing units  1101 . 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 communicate via, 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 (e.g., 2G, 3G, 4G, 4G, 4G long-term evolution (LTE), 5G, GSM, CDMA, or the like), 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.  11   , the device  1100  may include a battery  1107  that is used to store and provide power to the other components of the device  1100 . The battery  1107  may be a rechargeable power supply that is configured to provide power to the device  1100 . The battery  1107  may be coupled to charging systems (e.g., wired and/or wireless charging systems) and/or other circuitry to control the electrical power provided to the battery  1107  and to control the electrical power provided from the battery  1107  to the device  1100 . 
     The device  1100  may also include one or more displays  1108  configured to display graphical outputs. The displays  1108  may use any suitable display technology, including liquid crystal displays (LCD), organic light emitting diodes (OLED), active-matrix organic light-emitting diode displays (AMOLED), or the like. The displays  1108  may display graphical user interfaces, images, icons, or any other suitable graphical outputs. The one or more displays  1108  may include displays that are configured to display graphical outputs that are visible through the front and/or side walls of a device. The one or more displays  1108  may correspond to the display  114 , the display  402 , or any other displays described herein. 
     The device  1100  may also provide audio input functionality via one or more audio input systems  1109 . The audio input systems  1109  may include microphones, transducers, or other devices that capture sound for voice calls, video calls, audio recordings, video recordings, voice commands, and the like. 
     The device  1100  may also provide audio output functionality via one or more audio output systems (e.g., speakers)  1110 . The audio output systems  1110  may produce sound from voice calls, video calls, streaming or local audio content, streaming or local video content, alerts or notifications, or the like. 
     The device  1100  may also include a positioning system  1111 . The positioning system  1111  may be configured to determine the location of the device  1100 . For example, the positioning system  1111  may include magnetometers, gyroscopes, accelerometers, optical sensors, cameras, global positioning system (GPS) receivers, inertial positioning systems, or the like. The positioning system  1111  may be used to determine spatial parameters of the device  1100 , such as the location of the device  1100  (e.g., geographical coordinates of the device), measurements or estimates of physical movement of the device  1100 , an orientation of the device  1100 , or the like. 
     The device  1100  may also include one or more additional sensors  1112  to receive inputs (e.g., from a user or another computer, device, system, network, etc.) or to detect any suitable property or parameter of the device, the environment surrounding the device, people or things interacting with the device (or nearby the device), or the like. For example, a device may include temperature sensors, biometric sensors (e.g., fingerprint sensors, photoplethysmographs, blood-oxygen sensors, blood sugar sensors, electrocardiograph sensors, or the like), eye-tracking sensors, retinal scanners, humidity sensors, buttons, switches, or the like. 
     To the extent that multiple functionalities, operations, and structures described with reference to  FIG.  11    are disclosed as being part of, incorporated into, or performed by the device  1100 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the device  1100  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. Further, the systems included in the device  1100  are not exclusive, and the device  1100  may include alternative or additional systems, components, modules, programs, instructions, or the like, that may be necessary or useful to perform the functions described herein. 
     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, below, over, under, left, or right (or other similar relative position terms), do not necessarily refer to an absolute position relative to an external reference, but instead refer to the relative position of components within the figure being referred to. 
     As used herein, the phrase “at least one of” preceding a series of items, with the term “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list. The phrase “at least one of” does not require selection of at least one of each item listed; rather, the phrase allows a meaning that includes at a minimum one of any of the items, and/or at a minimum one of any combination of the items, and/or at a minimum one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or one or more of each of A, B, and C. Similarly, it may be appreciated that an order of elements presented for a conjunctive or disjunctive list provided herein should not be construed as limiting the disclosure to only that order provided.

Metadata:
Filing Date: 20210507
Publication Date: 20250114
Grant Date: 20250114
Priority Date: 20200513
Inventors: HIEMSTRA, DANIEL J.
DE JONG, ERIK G.
PANDYA, SAMEER
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G17/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/7435", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/14552", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/02427", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/256", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/339", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/02416", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G17/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G21/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G21/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G21/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04G21/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04G17/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G17/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/7435", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/339", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/256", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/14552", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/02427", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 76250432