Patent Publication Number: US-2023161299-A1

Title: Crown for an electronic watch

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation patent application of U.S. patent application Ser. No. 16/191,349, filed Nov. 14, 2018, and titled “Crown for an Electronic Watch” and claims the benefit of U.S. Provisional Patent Application No. 62/713,745, filed Aug. 2, 2018 and titled “Crown for an Electronic Watch,” the disclosures of which are hereby incorporated herein by reference in their entirety. 
    
    
     FIELD 
     The described embodiments relate generally to electronic devices, and more particularly to a crown for a wearable electronic device. 
     BACKGROUND 
     Electronic devices frequently use physical input devices to facilitate user interaction. For example, buttons, keys, dials, and the like can be physically manipulated by users to control operations of the device. Physical input devices may use various types of sensing mechanisms to translate the physical manipulation to signals usable by the electronic device. For example, buttons and keys may use collapsible dome switches to detect presses, while dials and other rotating input devices may use encoders or resolvers to detect rotational movements. 
     SUMMARY 
     An electronic watch includes a housing defining a side surface of the electronic watch, a transparent cover coupled to the housing and defining a front surface of the electronic watch, an image-sensing element, and a crown extending from the side of the housing and defining an imaging surface. The crown may include a light-directing feature configured to direct, onto the image-sensing element, an image of an object in contact with the imaging surface. 
     The electronic watch may further include a display positioned at least partially within the housing, and a touch sensor positioned below the transparent cover and configured to detect touch inputs applied to the transparent cover. The crown may include a head having a light-transmissive portion defining the imaging surface, and a light-transmissive shaft configured to receive light from the light-directing feature. The light-transmissive portion of the head may be transparent to infrared radiation and opaque to visible light. The light-transmissive shaft may be configured to guide the light to the image-sensing element. The head and the light-transmissive shaft may be portions of a monolithic light-transmissive member. 
     The light-directing feature may include an interface between a first material and a second material, the interface configured to reflect incident light. The first material may be a light-transmissive solid, and the second material may be air. The interface between the first material and the second material may be at least partially defined by an angled surface, and the angled surface may cause the incident light to be reflected towards the image-sensing element. 
     A wearable electronic device may include a housing, a display positioned at least partially within the housing, a crown at least partially external to the housing and defining an imaging surface along a peripheral portion of the crown, and an image-sensing element within the housing and configured to receive an image of an object in contact with the imaging surface. The imaging surface may be defined by a semi-transparent mirror coating. 
     The crown may include a light-transmissive member defining an angled surface configured to direct light from the imaging surface to the image-sensing element. The angled surface may have an angle configured to produce total internal reflection of the light. The wearable electronic device may further include a reflective material applied to the angled surface. 
     The light-transmissive member may at least partially define a head of the crown and a shaft of the crown. The wearable electronic device may further include a light source at least partially within the housing and configured to illuminate the object. 
     An electronic watch may include a housing, a display positioned at least partially within the housing, an image sensor at least partially within the housing and comprising an image-sensing element, and a crown. The crown may include a head portion defining an imaging surface external to the housing, a shaft portion extending at least partially into the housing, and a reflective feature directing light from the imaging surface through the shaft portion and towards the image-sensing element. The electronic watch may further include a transparent cover covering the display and a sensor configured to detect touch events applied to the transparent cover. 
     The reflective feature may include a curved surface configured to magnify an image of an object in contact with the imaging surface. The curved surface may define an interface between the head portion and air. 
     The crown may further include a cover member coupled to an end of the head portion. The head portion may define a cylindrical peripheral surface, and a peripheral surface of the cover member may be flush with the cylindrical peripheral surface of the head portion. 
    
    
     
       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 B  depict an example wearable electronic device; 
         FIGS.  2 A- 2 B  depict an example wearable electronic device being used; 
         FIG.  3    is a partial cross-sectional view of an example wearable electronic device having a crown with a light-directing feature; 
         FIG.  4 A  depicts an example wearable electronic device in a state of use; 
         FIG.  4 B  depicts an example image-sensing element corresponding to the state of use in  FIG.  4 A ; 
         FIG.  4 C  depicts an example wearable electronic device in another state of use; 
         FIG.  4 D  depicts an example image-sensing element corresponding to the state of use in  FIG.  4 C ; 
         FIG.  5 A  depicts an example wearable electronic device in a state of use; 
         FIG.  5 B  depicts an example image-sensing element corresponding to the state of use in  FIG.  5 A ; 
         FIG.  5 C  depicts an example wearable electronic device in another state of use; 
         FIG.  5 D  depicts an example image-sensing element corresponding to the state of use in  FIG.  5 C ; 
         FIG.  6 A  is a partial cross-sectional view of an example wearable electronic device having a crown with a light-directing feature; 
         FIG.  6 B  depicts an example image-sensing element of the wearable electronic device of  FIG.  6 A ; 
         FIG.  7    is a partial cross-sectional view of an example wearable electronic device having a crown with a curved light-directing feature; 
         FIG.  8    is a partial cross-sectional view of an example wearable electronic device having a crown that does not include a shaft; 
         FIG.  9    is a partial cross-sectional view of an example wearable electronic device having a crown with a cover member; 
         FIG.  10    is a partial cross-sectional view of an example wearable electronic device having a crown with a light-directing feature and a force sensor; 
         FIGS.  11 A- 11 B  are side views of example wearable electronic devices with crowns having imaging surfaces; and 
         FIG.  12    depicts example components of a wearable 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 description is 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 herein are generally directed to a crown of a wearable electronic device, such as an electronic watch (also referred to as a smart watch), and more particularly to a crown that includes an optical sensing system to detect user interactions with the crown. For example, users may interact with a crown by rotating the crown or, in the case of a crown that is rotationally constrained, sliding a finger over a surface of the crown. In order to sense the motion of the user&#39;s finger, a crown as described herein may include a window on the part of the crown that the user touches when interacting with the crown. The window may allow an image of the user&#39;s finger to be captured by an image sensor that is positioned within the housing. The image sensor, which may include an image-sensing element (e.g., a charge-coupled device (CCD)) in conjunction with associated processors and other components within the electronic watch, may determine how the user&#39;s finger has moved and control the operation of the electronic watch accordingly. For example, the watch may determine a speed and a direction of motion of the user&#39;s finger (or other suitable parameter), and cause a graphical output that is displayed on the watch&#39;s display to move at a speed and along a direction that is indicated by the detected motion. 
     As used herein, an image may refer to an optical representation of an object, which may be produced, transmitted, or propagated by lenses, mirrors, or the like. An image may be captured and stored, by an image sensor, as a multidimensional array having pixels that represent a small portion of the image formed on the image sensor. The multidimensional array may be stored as a single frame (e.g., a photograph) or a series of frames (e.g., a video). In order to detect motion using the image (e.g., the stored image), the image sensor may analyze multiple frames to determine, for example, a speed and direction of one or more features in the image. The features that are analyzed may include features of a user&#39;s skin (e.g., fingerprints, hair follicles), or any other optically detectable feature, texture, surface irregularity, image, or the like, of any object. In this way, the device may be responsive to skin (e.g., the skin of a user&#39;s finger or hand), a stylus, a gloved finger, or any other suitable object with optically detectable features. As used herein, analysis of an image by an image sensor and/or other components of an electronic device may refer to an analysis of a stored image (e.g., the stored multidimensional array, which may be a digital photograph or a video). 
     To facilitate capturing an image of the user&#39;s finger (or other implement used to interact with the crown), the crown may include light-transmissive materials and light-directing features that direct light (corresponding to an image of the user&#39;s finger) through the crown and onto an image-sensing element of an image sensor. For example, a peripheral surface of the crown (e.g., the cylindrical peripheral surface that a user touches to rotate the crown) may be light-transmissive, and the crown may have a reflecting feature to direct light from the peripheral surface onto the image-sensing element. In one such example, the crown may include a monolithic light-transmissive member that defines both a head portion and a shaft portion of the crown, as well as an angled surface that causes light (e.g., the light corresponding to an image of the user&#39;s finger) to be reflected at an approximately 90 degree angle so that the light may be directed through the shaft and into an enclosure of the watch. More particularly, when a user places a finger on the peripheral surface of the head, the light corresponding to an image of the user&#39;s finger may be initially directed into the head along a radial direction (relative to the cylindrical peripheral surface of the head). However, an image-sensing element may be within the housing along an axial direction of the head. Accordingly, the head may have an angled surface formed into the material that effectively changes the direction of the light (e.g., reflects or otherwise redirects the light) so that the light is directed along the axis of the crown and into the watch. In this way, the image of the user&#39;s finger (or other implement or object) is directed onto an image-sensing element within the watch, allowing the watch to analyze the image and control the operation of the device accordingly. 
     The optical crown system described herein may be used with both freely rotatable crowns (e.g., crowns that can rotate about an axis an indefinite number of turns) as well as rotationally constrained crowns. As used herein, a “rotationally constrained” crown or component refers to a component that is not free to rotate more than a full revolution under normal use conditions (e.g., when manipulated by the hands of a person). Thus, rotationally constrained components include both rotationally fixed components and partially rotatable components. 
     In the case of a rotationally constrained crown, if a user attempts to rotate the crown to operate the device, the crown may not physically rotate. Instead, the user&#39;s fingers may slide along a surface of the crown while the crown remains stationary. As used herein, a finger or object “sliding” along a surface may refer to the finger (or other object) moving along the surface of the crown while the finger (or other object) is in contact with the surface. In the case of a rotating crown, as the user&#39;s finger moves forward to rotate the crown, the part of the user&#39;s finger that is touching the crown changes. In either case, as the user&#39;s finger moves, the image that is projected or incident on the image-sensing element may include a moving image of the surface of the user&#39;s finger. The image sensor may analyze the movement of the image to determine how to manipulate the graphical output or other property of the watch. The image sensor may use features of the user&#39;s skin, such as the ridges of the user&#39;s skin (or any other texture or optically detectable feature), to determine the speed and direction of motion. 
     Advantageously, the crown described herein can detect inputs even under conditions when other types of touch sensors may fail. For example, some touch-sensing technologies use capacitive sensors to detect touch events or inputs. The effectiveness of capacitive sensors may be reduced, however, by gloves, clothing, overly wet or dry skin, lotions, or the like. By detecting motion via images, the optical sensing structures described herein may avoid such negative effects and may operate effectively over a broader range of conditions and may sense movement of objects other than bare skin. 
       FIGS.  1 A- 1 B  depict an electronic device  100 . The electronic device  100  is depicted as an electronic watch, though this is merely one example embodiment of an electronic device and the concepts discussed herein may apply equally or by analogy to other electronic devices, including mobile phones (e.g., smartphones), tablet computers, notebook computers, head-mounted displays, digital media players (e.g., mp3 players), or the like. 
     The electronic device  100  includes a housing  102  and a band  104  coupled to the housing. The band  104  may be configured to attach the electronic device  100  to a user, such as to the user&#39;s arm or wrist. 
     The electronic device  100  also includes a transparent cover  108  coupled to the housing  102 . The cover  108  may define a front face of the electronic device  100 . For example, in some cases, the cover  108  defines substantially the entire front face and/or front surface of the electronic device. The cover  108  may also define an input surface of the device  100 . For example, as described herein, the device  100  may include touch and/or force sensors that detect inputs applied to the cover  108 . The cover  108  may be formed from or include glass, sapphire, a polymer, a dielectric, or any other suitable material. 
     The cover  108  may cover at least part of a display  109  that is positioned at least partially within the housing  102 . The display  109  may define an output region 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  109  may include a liquid-crystal display (LCD), organic light emitting diode display (OLED), or any other suitable components or display technology. 
     The display  109  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 techniques. Using touch sensors, the device  100  may detect touch inputs applied to the cover  108 , including detecting locations of touch inputs, motions of touch inputs (e.g., the speed, direction, or other parameters of a gesture applied to the cover  108 ), or the like. Using force sensors, the device  100  may detect amounts or magnitudes of force associated with touch events applied to the cover  108 . 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. Touch and/or force sensors usable with wearable electronic devices, such as the device  100 , are described herein with respect to  FIG.  12   . 
     The electronic device  100  also includes a crown  112  having a head, protruding portion, or component(s) or feature(s) positioned along a side surface of the housing  102 . At least a portion of the crown  112  may protrude from the housing  102 , and may define a generally circular shape or a circular exterior surface. The exterior surface of the crown  112  may be textured, knurled, grooved, or may otherwise have features that may improve the tactile feel of the crown  112  and/or facilitate rotation sensing. The exterior surface of the crown  112  may also have one or more light-transmissive areas, such as a light-transmissive window, that define one or more imaging surfaces. An imaging surface may refer to a surface that allows an image to be captured of an object (e.g., a finger) that is touching that surface. For example, a light-transmissive window may allow an image to be captured, through the window, of a finger that is in contact with the window. Accordingly, the light-transmissive window may define an imaging surface. 
     The imaging surface or surfaces may enable the device  100  to capture an image of the user&#39;s finger while the finger is interacting with the crown  112  (e.g., in order to determine input parameters such as a speed and direction of an input, as described herein). The light-transmissive areas may be transparent to some wavelengths of light and substantially opaque to others. For example, if the device  100  uses infrared imaging to capture an image of the user&#39;s finger, the light-transmissive areas may be transparent to infrared wavelengths while being opaque to visible light. 
     The crown  112  may afford a variety of potential user interactions. For example, the crown  112  may be rotationally constrained (e.g., rotationally fixed or partially rotatable), and may include or be associated with sensors that detect when a user slides one or more fingers along a surface of the crown  112  in a movement that resembles rotating the crown  112  (or that would result in rotation of a freely rotating crown). More particularly, where the crown  112  is rotationally fixed or rotationally constrained, a user input that resembles a twisting or rotating motion may not actually result in any substantial physical rotation that can be detected for the purposes of registering an input. Rather, the user&#39;s fingers (or other object) will move in a manner that resembles twisting, turning, or rotating, but does not actually continuously rotate the crown  112 . As another example gesture that may be detected, a user attempting to rotate a rotationally fixed crown by applying a substantially tangential force to a surface of the crown  112  (as shown in  FIGS.  2 A- 2 B , for example) may also result in a sliding gesture along a surface of the crown  112 . Thus, in the case of a rotationally fixed or constrained crown  112 , an image sensor within the device  100  may detect inputs that result from a gesture that has the same motion as (and thus may feel and look the same as or similar to) rotating a rotatable crown. 
     In some cases, the crown  112  may be rotationally free or may include a rotationally free member that is free to rotate relative to the housing  102 . More particularly, the rotationally free member may have no rotational constraints, and thus may be capable of being rotated indefinitely (or a sufficiently large number of turns that a user does not typically reach a hard-stop under normal use conditions). Even where the crown  112  or a portion thereof can rotate, the crown  112  may be configured so that light reflected from the user&#39;s finger is directed from an imaging surface of the crown  112  onto an image-sensing element within the housing  102 . 
     Thus, both rotationally constrained and rotationally free crowns may detect gestures resembling a twisting, turning, or rotating motion, regardless of whether the crown rotates or not. As used herein, a twisting, turning, or rotating motion applied to a crown may be referred to as a gesture input or a rotational input (even if the crown itself does not physically rotate). 
     In cases where the crown  112 , or a member or component of the crown  112 , is capable of some rotation, it may rotate about a rotation axis (e.g., it may rotate as indicated by arrow  103  in  FIG.  1 A ). The crown  112 , or a member or component of the crown  112 , may also be translatable relative to the housing  102  to accept axial inputs. For example, the crown  112  may be movable or translatable along the rotation axis, towards and/or away from the housing  102  (as indicated by arrow  105  in  FIG.  1 A ). The crown  112  may therefore be manipulated by pushing and/or pulling on the crown  112 . 
     The crown  112  may be able to translate any suitable distance. For example, a crown  112  may include a dome switch to register axial inputs, and the crown  112  may move a sufficient distance to facilitate physical actuation of the dome switch. In other cases, such as where a force sensor is used to detect axial inputs, the crown  112  may move a sufficient distance to facilitate force sensing. The distance that the crown  112  can translate or move may be any suitable distance, such as about 1 mm, 0.5 mm, 0.2 mm, 0.1 mm, 0.05 mm or any other suitable distance. 
     Alternatively, the crown  112  may be fixed or otherwise substantially non-translatable. In such cases, axial inputs applied to the crown  112  may be detected in other ways. For example, the crown  112  may include or be part of a contact sensor (described more fully below), such as a capacitive or resistive touch sensor, that determines when and optionally where a user&#39;s finger is in contact with the crown  112 . The crown  112  may also use an optical sensing scheme to detect axial inputs. For example, as noted above, the crown  112  or a portion of the crown may be light-transmissive to allow light (corresponding to an image of the user&#39;s finger) to be directed from a peripheral surface of a head onto an image-sensing element. To facilitate axial input sensing, the crown  112  may also define an optical path from an end  113  of the crown  112  to an image-sensing element so that the image sensor can determine when a user&#39;s finger (or other object) is in contact with the end  113  of the crown  112 . 
     The device  100  may include a force sensor to detect axial forces that are applied to the crown  112 . The force sensor may include or use any suitable force sensing components and may use any suitable technique for sensing force inputs. For example, a force sensor may include a strain sensor, capacitive gap sensor, or other force sensitive structure that is configured to produce an electrical response that corresponds to an amount of force (e.g., axial force) applied to the crown  112 . The electrical response may increase continuously as the amount of applied force increases, and as such may provide non-binary force sensing. Accordingly, the force sensor may determine, based on the electrical response of the force sensing components, one or more properties of the applied force associated with a touch input (e.g., a magnitude of the applied axial force). 
     As described herein, gesture inputs (e.g., rotational-style inputs applied to a rotationally free or rotationally constrained crown) and axial inputs (e.g., translations or axial forces) may control various operations and user interfaces of the electronic device  100 . In particular, inputs to the crown  112  may modify the graphical output of the display  109 . For example, a rotational movement of the crown  112  or a gesture applied to the crown  112  may zoom, scroll, or rotate a user interface or other object displayed on the display  109  (among other possible functions), while translational movements 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). 
     The crown  112  may also be associated with or include a contact sensor that is configured to detect contact between a user and the crown  112  (e.g., touch inputs or touch events applied to the crown  112 ). The contact sensor may detect even non-moving contacts between the user and the crown  112  (e.g., when the user touches the crown  112  but does not rotate the crown or apply a sliding gesture to the crown  112 ). Contact sensing functionality may be provided by the same optical sensing system that also detects gestures (e.g., a finger sliding along a surface of a crown or the housing), or it may be provided by a separate sensor. The contact sensor may include or use any suitable type of sensor(s), including capacitive sensors, resistive sensors, magnetic sensors, inductive sensors, optical sensors, or the like. In some cases, the crown  112  itself, or components of the crown, may be conductive and may define a conductive path between the user (e.g., the user&#39;s finger) and a contact sensor. For example, the crown may be formed from or include metal, and may itself act as an electrode for conductively coupling a capacitive sensor to the user. 
     The device  100  may also include one or more haptic actuators that are configured to produce a tactile output through the crown  112 . For example, the haptic actuator may be coupled to the crown  112  and may be configured to impart a force to the crown  112 . The force may cause the crown  112  to move (e.g., to oscillate or vibrate translationally and/or rotationally, or to otherwise move to produce a tactile output), which may be detectable by a user when the user is contacting the crown  112 . The haptic actuator may produce tactile output by moving the crown  112  in any suitable way. For example, the crown  112  (or a component thereof) may be rotated (e.g., rotated in a single direction, rotationally oscillated, or the like), translated (e.g., moved along a single axis), or pivoted (e.g., rocked about a pivot point). In other cases, the haptic actuator may produce tactile outputs using other techniques, such as by imparting a force to the housing  102  (e.g., to produce an oscillation, vibration, impulse, or other motion), which may be perceptible to a user through the crown  112  and/or through other surfaces of the device  100 , such as the cover  108 , the housing  102 , or the like. Any suitable type of haptic actuator and/or technique for producing tactile output may be used to produce these or other types of tactile outputs, including electrostatics, piezoelectric actuators, oscillating or rotating masses, ultrasonic actuators, reluctance force actuators, voice coil motors, Lorentz force actuators, or the like. In some cases, haptic outputs may be produced by collapsible domes, springs, or other mechanical components. 
     Tactile outputs may be used for various purposes. For example, tactile outputs may be produced when a user presses the crown  112  (e.g., applies an axial force to the crown  112 ) to indicate that the device  100  has registered the press as an input to the device  100 . As another example, tactile outputs may be used to provide feedback when the device  100  detects a rotation of the crown  112  or a gesture being applied to the crown  112 . For example, a tactile output may produce a repetitive “click” sensation as the user rotates the crown  112  or applies a gesture to the crown  112 . Tactile outputs may be used for other purposes as well. 
     The electronic device  100  may also include other inputs, switches, buttons, or the like. For example, the electronic device  100  includes a button  110 . The button  110  may be a movable button (as depicted) or a touch-sensitive region of the housing  102 . The button  110  may control various aspects of the electronic device  100 . For example, the button  110  may be used to select icons, items, or other objects displayed on the display  109 , to activate or deactivate functions (e.g., to silence an alarm or alert), or the like. 
       FIGS.  2 A- 2 B  show a front and side view, respectively, of a device  200  during one example use condition. The device  200  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100 . Accordingly, details of the device  100  described above may apply to the device  200 , and for brevity will not be repeated here. 
     In the example shown in  FIGS.  2 A- 2 B , the wearable device  200  includes a crown  212  that a user may contact to provide input through the crown  212 . The crown  212  may define an imaging surface  216  that is positioned in a location where a user is likely to touch the crown  212  when interacting with and/or providing input to the crown  212 . In some cases, the imaging surface  216  may extend around the entire peripheral portion or surface of the crown  212 . Thus, the crown  212  and an associated image sensor may detect inputs applied to any part of the periphery of the crown  212 . In other cases, the imaging surface  216  may extend along less than the entire periphery of the crown  212 . 
     The imaging surface  216 , which may be defined by a light-transmissive portion of the crown  212 , may in optical communication with an image-sensing element within the device  200  to facilitate the image sensor capturing and analyzing an image of whatever object is in contact with the imaging surface  216  (e.g., a bare finger, a gloved finger). For example, the crown  212  may include a light-directing feature, such as an angled surface that changes the direction of the light that corresponds to an image of the object so that it is incident on the image-sensing element. In some cases, the crown  212  includes a monolithic light-transmissive member that defines the imaging surface  216 , a shaft of the crown  212 , as well as a light-directing feature to redirect light down the shaft of the crown and towards the image-sensing element. 
       FIGS.  2 A- 2 B  show a user interacting with the crown  212  to provide an input to the device  200 . In the case of a rotationally constrained crown, the crown will not continuously rotate in response to the force applied by the finger  201  moving along the direction indicated by arrow  217  (while the finger is in contact with the crown  212 ). Rather, the finger  201  will slide along a surface of the crown  212 . In the case of a rotationally free crown, the force applied to the crown  212  by the user&#39;s finger  201  causes the crown  212  (or a head or other component of the crown  212 ) to rotate relative to the housing  202 . In either case, an image of the user&#39;s finger  201  is projected or otherwise incident on the image-sensing element within the device  200 , and the image sensor detects the movement of the finger  201  sliding along the imaging surface  216  and causes the device  200  to take an action in response to the rotation. For example, as shown in  FIG.  2 A , upon detection of the motion of the finger  201 , the device  200  may cause a graphical output  207  on a display  209  to move in accordance with the movement of the finger  201 . A movement of the finger  201  in the direction indicated by arrow  217  may result in the graphical output  207  moving in the direction indicated by arrow  215 . A movement of the finger  201  in the opposite direction may result in the graphical output  207  moving in the opposite direction. Rotating the crown  212  or sliding a finger along a surface of the crown  212  may change other operational properties of the device  200  in addition to or instead of scrolling a graphical output  207 . For example, sliding a finger along the surface of the crown  212  may change parameters or settings of the device, control a zoom level of a graphical output, rotate a displayed graphical output, translate a displayed graphical output, change a brightness level of a graphical output, change a time setting, scroll a list of displayed items (e.g., numbers, letters, words, images, icons, or other graphical output), or the like. 
     In some cases, the graphical output  207  may also be responsive to inputs applied to a touch-sensitive display  208 . The touch-sensitive display  208  may include or be associated with one or more touch and/or force sensors that extend along an output region of a display and which may use any suitable sensing elements and/or sensing techniques to detect touch and/or force inputs applied to the touch-sensitive display  208 . The same or similar graphical output  207  manipulations that are produced in response to inputs applied to the crown  212  may also be produced in response to inputs applied to the touch-sensitive display  208 . For example, a swipe gesture applied to the touch-sensitive display  208  may cause the graphical output  207  to move along the direction indicated by the arrow  215  ( FIG.  2 A ). As another example, a tap gesture applied to the touch-sensitive display  208  may cause an affordance to be selected or activated. In this way, a user may have multiple different ways to interact with and control an electronic watch, and in particular the graphical output  207  of an electronic watch. Further, while the crown  212  may provide overlapping functionality with the touch-sensitive display  208 , using the crown allows for the graphical output of the display to be visible (without being blocked by the finger that is providing the touch input). 
       FIG.  3    is a partial cross section of an electronic device  400 , corresponding to a view along line A-A in  FIG.  1 B . The device  300  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  300 , and for brevity will not be repeated here. 
     The device  300  includes a crown  312  positioned along a side of a housing  302 . The crown  312  may include a head portion or head  313  and a shaft portion or shaft  315 . The head  313  and the shaft  315  may be a single monolithic component, as shown, or they may be separate components joined together (e.g., via adhesive, a threaded interface, fasteners, clips, rivets, fusion bonding, or the like). Where the head  313  and shaft  315  are separate components, index matching fluid or material may be used to occupy voids or gaps between the head  313  and shaft  315  (or between any other components of a crown  312 ). 
     The head  313  and the shaft  315  may be formed of or include a light-transmissive material, which may define an imaging surface  316 . For example, head  313  and/or the shaft  315  may be formed from a light-transmissive solid such as an acrylic, glass, transparent ceramic, sapphire, polycarbonate, quartz, or another suitable material. The solid light-transmissive material may be optically transparent (e.g., clear and uncolored), or it may be transparent some wavelengths of light and opaque (or substantially opaque) to others. For example, if the device uses infrared imaging to capture an image of the user&#39;s finger, the light-transmissive areas may be transparent to infrared wavelengths while being opaque to visible light. In some cases, the light-transmissive material of the crown  312  may be coated or otherwise treated so that it is visually opaque. For example, a semi-transparent mirror coating may be applied to an otherwise transparent or light-transmissive material. This may allow the crown  312  to appear, to the wearer, to be opaque and/or metallic, while still allowing light reflected by the portion of the user&#39;s finger  301  that is in contact with the crown  312  to enter the crown  312  through the imaging surface  316 . As another example, a visibly opaque but infrared-transparent paint, film, ink, or other coating or material may be applied to the crown  312  (and in particular the imaging surface  316 ) to provide a visually opaque appearance while still facilitating optical imaging of the user&#39;s finger  301 . As used herein, light-transmissive may be used to refer to something that is transparent or otherwise allows light and/or images to propagate therethrough. In some cases, transparent or light-transmissive materials or components may introduce some diffusion, lensing effects, filtering effects (e.g., color filtering), distortions, attenuation, or the like (e.g., due to surface textures) while still allowing objects or images to be seen or transmitted through the materials or components, and such deviations are understood to be within the scope of the meaning of transparent or light-transmissive. Moreover, components such as a crown, shaft, or head that are formed of or include light-transmissive materials and that function as described herein may be referred to as, for example, a light-transmissive crown, a light-transmissive shaft, and a light-transmissive head. 
     The device  300  also includes an image-sensing element  324  within the housing  302  and positioned adjacent an end of the shaft  315 . An image of the user&#39;s finger  301  may be directed onto the image-sensing element  324  so that the image can be captured and analyzed to determine input parameters of an input gesture applied to the crown  312 . The image-sensing element  324  may be positioned on a support  322  as shown in  FIG.  3   , though other mounting and/or support structures are also contemplated. 
     The image-sensing element  324  is one example of an optical sensing element that may be used. In particular, the image-sensing element  324  may be an optical sensing element with multiple pixels or other sensing regions that capture individual portions of an image, and allow the image sensor (or other optical sensor) to detect and/or store photographs, videos, and the like. In other cases, however, one or more other optical sensing elements may be used, such as photodiodes, single-pixel sensors, photovoltaic cells, or the like. In such cases, the optical sensing element(s) may detect changes in light caused by the presence and/or motion of an object relative to the imaging surface  316  of the crown  312 , and may cause the device  300  to take actions based on the detected inputs (including but not limited to controlling any user interface animations or other device functions described herein). 
     As noted above, the imaging surface  316  is not directly in line with the image-sensing element  324 . Accordingly, the crown  312  may include a light-directing feature  326  that directs light corresponding to the image of the user&#39;s finger from the imaging surface onto the image-sensing element  324 . As shown in  FIG.  3   , the light-directing feature  326  includes an angled surface of the light-transmissive material of the crown  312 . The angled surface defines an interface between materials having different optical indices (e.g., the light-transmissive material and a different material, such as air). When the light corresponding to an image of the user&#39;s finger  301  is incident on the interface defined by the angled surface (as represented by arrow  319 ), all or part of the light may be reflected at an angle (e.g., a 90 degree angle) towards the image-sensing element  324 . For example, the angled surface may direct the light (e.g., by causing the light to be reflected) through the shaft  315  of the crown, which may also be light-transmissive. Thus, the shaft  315  guides the reflected light towards the image-sensing element  324  (as indicated by arrow  321 ). In cases where the light-directing feature  326  reflects light towards the image-sensing element  324 , it may be referred to as a reflective feature. 
     The particular angle of the angled surface may be selected based on various factors, such as the optical properties of the light-transmissive material, the position of the image-sensing element  324  relative to the imaging surface  316 , the degree of reflectance desired, and the like. In some cases, the angle of the angled surface has an angle configured to produce total internal reflection of the light. For example, the angled surface may be configured so that the angle of incidence  327  of the light from the object on the imaging surface  316  is equal to or greater than the critical angle for the crown/air interface defined by the angled surface. This configuration may produce total internal reflection of the incident light. More particularly, all of the light reflected by the user&#39;s finger  301  towards the light-directing feature  326  may be reflected by the crown/air interface defined by the angled surface. 
     The angle and/or shape of the light-directing feature  326  that results in total internal reflection may depend, for example, on the geometry and material(s) of the crown  312 , the relative angles of the imaging surface  316  and the axis of the shaft  315 , and the material that is in contact with the angled surface (air, as shown in  FIG.  3   ). In the case where the crown  312 , or the optically operative portions of the crown  312 , is acrylic, the critical angle may be about 41 degrees. Accordingly, the light-directing feature  326  may be configured so that the angle of incidence  327  is equal to or greater than about 41 degrees (e.g., about 41 degrees, about 45 degrees, about 50 degrees). In some cases, the angle of incidence on the light-directing feature  326  may be less than the critical angle, in which case some of the light that forms the image may be transmitted through the angled surface, rather than being reflected along the shaft  315 . This may be acceptable, as it may not be necessary to achieve total internal reflection. In particular, the light that is reflected by the light-directing feature  326  and incident on the image-sensing element  324  (even though it is less than all of the light being reflected by the user&#39;s finger) may be sufficient to allow the image sensor to analyze the image and ultimately detect the input. 
     In some cases, the exterior surface of the light-directing feature  326  includes a coating, film, or other material or treatment that increases the reflectivity of the imaging directing feature. For example, a mirror coating (or other reflective material) may be applied to the exterior surface of the light-directing feature  326 . In such cases, it may not be necessary for the angle of incidence to be at or greater than a critical angle, as the mirror coating may ensure that all or substantially all of the light forming the image is reflected along the shaft or otherwise towards an image-sensing element. 
     As described herein, the imaging surface  316  of the crown  312  may extend around the entire periphery of the head  313 . In such cases, the light-directing feature  326  may have a generally circular configuration so that the light-directing feature  326  directs the light corresponding to the image of the user&#39;s finger (or other object or implement) towards the image-sensing element  324  no matter where the finger contacts the periphery of the head  313 . For example, the light-directing feature  326  may resemble a conical recess in the end of the head  313 . Arrows  323  and  325  in  FIG.  3    show an example light path for an object in contact with a bottom portion of the head  313 . Due to the radial symmetry of the head  313  and the light-directing feature  326 , these arrows may be generally representative of a light path for an object in contact with any portion of the peripheral surface of the head  313 . In cases where the imaging surface  316  does not extend around the entire periphery of the head  313 , the light-directing feature  326  need not be circular, though it may still have the circular configuration. 
     Where the imaging surface  316  extends around the entire periphery of the head  313 , an image of a user&#39;s wrist (which may be proximate to the bottom portion of the peripheral surface of the head  313 ) may be directed onto the image-sensing element  324  when the device is being worn. To avoid the image of the user&#39;s wrist causing false inputs to the device, the image sensor may ignore images received via the bottom surface of the head  313  under certain conditions. For example, if the only received or detected image is received via the bottom surface of the head  313 , the device  300  may ignore the image, as users are unlikely to turn the crown  312  by touching only the bottom surface (e.g., in the small area between the crown and the wearer&#39;s wrist). As another example, skin patterns or characteristics may differ between a wrist and a finger, and the device  300  may ignore any image that does not contain characteristics of the skin of a finger. 
     In order to illuminate the finger  301  while it is in contact with the imaging surface  316 , the device  300  may include a light source  330  within the housing  302 . The light source  330  may direct light through the shaft  315  towards the light-directing feature  326 , which in turn directs the light towards the imaging surface  316 , thereby illuminating the user&#39;s finger and allowing the image-sensing element  324  to capture an image of the user&#39;s finger  301 . The light source  330  may be configured to emit light of any suitable wavelength(s), based on the particular type of light and/or electromagnetic radiation that the image-sensing element  324  is configured to detect. For example, the light source  330  may emit infrared radiation. The light source  330  (or any other suitable light source) may be integrated with any of the crowns or devices described herein. 
     In some cases, the device  300  uses dark field illumination components and techniques for illuminating and imaging an object that is in contact with the imaging surface  316 . Such components may be integrated with the crown  312  or otherwise positioned within the crown  312  or the housing  302  as appropriate to provide suitable illumination and optical detection via the crown  312 . 
     As noted above, the crown  312  may be rotationally constrained or rotationally free, and may also be axially fixed, or it may be translatable along its axis to accept axial inputs. The crown  312  may also be coupled to or otherwise integrated with the housing  302  in any suitable way. For example, the shaft  315  may extend into the housing  302  through an opening  317 . A sealing member  320 , such as an elastomeric member or other material or component(s), may form a seal between the shaft  315  and the housing  302  to prevent ingress of liquids, debris, or other contaminants. The sealing member  320  may seal the opening  317  while also allowing the crown  312  to move relative to the housing  302 , if the crown  312  is configured to rotate and/or translate. In cases where the shaft  315  is rotationally constrained (e.g., rotationally fixed or partially rotatable), it may still be able to translate axially. As such, the sealing member  320  may seal the opening while allowing the shaft  315  to move axially within the opening  317 . In other cases, the shaft  315  may be fixed to the housing  302 , such as with adhesive, welds, fusion bonds, or the like. In such cases the sealing member  320  may be omitted. 
     As described with respect to  FIG.  3   , the crown  312  may be configured to redirect the light corresponding to an image of a user&#39;s finger from an imaging surface onto an image-sensing element that is offset or otherwise not in line with the imaging surface.  FIGS.  4 A- 4 D  illustrate how the image of the wearer&#39;s finger may appear on an image-sensing element and how motion of the user&#39;s finger along an imaging surface may be detected by an image sensor. 
       FIG.  4 A  shows an example electronic device  400  receiving an input from a finger  401 . The device  400  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  400 , and for brevity will not be repeated here. The device  400  may include a crown  412  (which may be an embodiment of the crown  312  or any other crown described herein). As shown in  FIG.  4 A , which is a side view of the device  400 , a portion  419  of the finger  401  is in contact with an imaging surface  416  of the crown  412 .  FIG.  4 B  shows an example image-sensing element  424  (which may be an embodiment of the image-sensing element  324 ,  FIG.  3   ) with an image  426  of the portion  419  of the finger  401 . The image  426  (or light that corresponds to the image) may be directed onto the image-sensing element  424  by the crown  412  along a path as indicated by the arrows  319 ,  321  in  FIG.  3   . As shown in  FIGS.  4 B and  4 D  (and elsewhere in the figures), the image-sensing element  424  is a square, though any other suitable shape may be used, including circular, rectangular, oval, or the like. 
     In the configuration shown in  FIGS.  4 A- 4 D , the crown  412  may have an imaging surface that extends around the entire periphery of the crown  412 . Accordingly, the image  426  is shown positioned along a top portion of the image-sensing element  424 , resulting from the fact that the user&#39;s finger  401  is in contact with a top-facing surface of the crown  412 . Were the user&#39;s finger  401  to be in contact with a bottom surface of the crown  412 , for example, the image may be incident on a bottom portion of the image-sensing element  424 . 
       FIGS.  4 C and  4 D  show the electronic device  400  and image-sensing element  424 , respectively, after the finger  401  has moved forward (e.g., in the direction of arrow  417 ). Notably, the portion  421  of the user&#39;s finger  401  that is in contact with the imaging surface  416  has changed, though the area of the image-sensing element  424  that receives the image  426  has not changed. However, because the user&#39;s finger  401  has moved, the features of the user&#39;s finger that are visible to the image-sensing element  424  (e.g., the ridges or other features of the skin of the finger  401 ) have moved. For example, feature  430 , which may correspond to a ridge of a fingerprint, a texture of a fabric material of a glove, or the like, has moved along the image- sensing element  424 . A processor or other component of an image sensor may analyze the image  426  and use features such as the feature  430  to determine a speed and/or direction of motion of the user&#39;s finger, and the device  400  may use that information to change or control an operation of the device  400  (e.g., to move or scroll a graphical output on a display). 
     While  FIGS.  4 A- 4 D  show a bare finger and a fingerprint, any other object or implement may be used in place of a bare finger. For example, if a gloved finger is used to provide a gesture input to the crown  412 , the image sensor may use a feature of the material of the glove to determine a speed and/or direction of motion. Indeed, the image sensor may determine motion of any suitable object by analyzing a texture, surface irregularity, or some other optically detectable feature of the object. 
     A crown, and more particularly, a head of a crown, may also be shaped or configured to act as a lens to aid in the image sensing functionality of a device.  FIGS.  5 A- 5 D  illustrate how a lensing feature on a crown may enable a device to reject or otherwise ignore images that do not correspond to a finger in contact with the crown. For example, a lensing feature may be configured so that only objects in direct contact with the crown are in sharp focus. 
       FIG.  5 A , shows an example electronic device  500  receiving an input from a finger  501 . The device  500  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  500 , and for brevity will not be repeated here. The device  500  may include a crown  512  (which may be an embodiment of the crown  312  or any other crown described herein). As shown in  FIG.  5 A , which is a side view of the device  500 , a portion of the finger  501  is in contact with an imaging surface  516  of the crown  512 .  FIG.  5 B  shows an example image-sensing element  524  (which may be an embodiment of the image-sensing element  324 ,  FIG.  3   ) with an image  526  of the finger  501 . Under these conditions, the image  526  is in focus so that the features of the user&#39;s finger  501  are clearly defined and the image sensor can easily analyze the motion (if any) of the finger  501 . 
       FIG.  5 C  shows the electronic device  500  with the finger  501  elevated a distance off of the imaging surface  516  (e.g., moved in a direction indicated by the arrow  517 ). The crown  512  may have a shape or feature that acts as a lens so that objects that are not in direct contact with (or within a threshold distance of) the crown  512  are out of focus. The threshold distance may be about 0.1 mm, 0.5 mm, 1.0 mm, 2.0 mm, or any other suitable distance.  FIG.  5 D  shows a representation of an out-of-focus image  526 . The image sensor may be able to ignore the motion of images that are not in focus, thereby preventing images from the surrounding environment from triggering inputs to the device. In some cases, instead of or in addition to a lensing feature, the device  500  may use a contact sensor to determine when an object is in contact with the crown  512 , and ignore image motion when there is nothing contacting the crown  512 . 
     As noted above, in some cases an optical crown as described herein may be configured to detect axial inputs, such as a tap or press on an end surface of the crown.  FIG.  6 A  illustrates an example electronic device  600  with an optical crown that incorporates both optical gesture sensing (as described above), as well as axial touch sensing. 
     The device  600  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  600 , and for brevity will not be repeated here. The device  600  may include a crown  612  (which may be an embodiment of the crown  312  or any other crown described herein). The crown  612  may include a head  613  and a shaft  615 . The crown  612  may include a light-directing feature  626 , which operates substantially the same as the light-directing feature  626 , and directs an image from an imaging surface  616  towards an image-sensing element  624 . The device may include a sealing member  620  between the shaft  615  and a housing  602 , and the image-sensing element  624  may be positioned on a support  622 . 
     The crown  612  also includes an axial imaging surface  628 . The axial imaging surface  628  may be configured to allow light corresponding to an image of an object in contact with an end surface of the crown  612  to pass through the shaft  615  and onto the image-sensing element  624 . The image sensor may be configured to determine, based on the image received on the image-sensing element  624 , whether a user&#39;s finger (or other object) is in contact with the end surface of the head  613 . In some cases, the axial imaging surface  628  may have a curvature or lensing feature that operates similar to that described with respect to  FIGS.  5 A- 5 D , so that only a finger or object that is actually in contact with the end surface of the head  613  cause the image sensor to positively identify an axial touch input. 
       FIG.  6 B  shows a representation of the image-sensing element  624 , showing example images  632 ,  634  corresponding to a gesture applied to a peripheral surface of the crown (image  632 ), and an axial touch input (image  634 ). As shown, the image  634  is positioned on a center of the image-sensing element  624 . Accordingly, the image sensor may be configured to analyze the center of the image-sensing element  624  to determine when an axial touch input has been applied (e.g., by detecting an in-focus image of a user&#39;s finger), and to analyze the peripheral portion of the image-sensing element  624  to detect a gesture input applied to the peripheral surface of the crown  612 . The device  600  may take any suitable action in response to detecting an axial touch input, such as turning on or off the device (or a display of the device), selecting a user interface element being displayed on the display, activating or deactivating a device function, or the like. 
     In some cases, a light-directing feature may define a curved surface that not only directs light from an imaging surface onto an image-sensing element, but also adjusts, focuses, or otherwise modifies the image.  FIG.  7    illustrates an example electronic device  700  with an optical crown having a light-directing feature with a curved surface to both redirect the light and modify the image of the user&#39;s finger. 
     The device  700  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  700 , and for brevity will not be repeated here. The device  700  may include a crown  712  (which may be an embodiment of the crown  312  or any other crown described herein). The crown  712  may include a head  713  and a shaft  715 . The crown  712  may include a light-directing feature  726  that directs light from an imaging surface  716  (e.g., reflected by a user&#39;s finger) to an image-sensing element  724 , as described above. The device  700  may include a sealing member  720  between the shaft  715  and a housing  702 , and the image-sensing element  724  may be positioned on a support  722 . 
     The light-directing feature  726  includes a curved surface  728 . The curved surface  728  may be configured so that an angle of incidence of the light from an object (e.g., a user&#39;s finger) is equal to or greater than a critical angle of the interface defined by the curved surface  728 , thus producing total internal reflection of the light. Further, the curved surface  728  may be configured to magnify the image so that the image occupies a greater area of the image-sensing element  724 .  FIG.  7    illustrates the magnification of the image by showing the rays  730 ,  732 ,  734 , and  736  diverging through the shaft  715 . 
     As shown, the curved surface  728  is concave (e.g., as viewed from the exterior of the crown  712 ), though the curved surface  728  may have other configurations and/or shapes, such as convex shapes, aspherical shapes, combination concave and convex shapes (e.g., having concave and convex regions), or the like. In some cases, the surface is not only curved, but has flat regions, stepped regions, or other complex geometries. 
     The crown  712  shown in  FIG.  7    has an imaging surface along the entire periphery of the head  713 , and as such the curved surface  728  may be configured so that a magnified image does not extend past a midpoint of the image-sensing element  724 . In examples where the imaging surface extends along less than the entire periphery, the image may be magnified to a greater extent. Thus, for example, a finger applied to the top portion of the head  713  may result in an image that occupies the entire image-sensing element  724  (rather than less than half of the image-sensing element, which may occur with a full-periphery imaging surface). 
     The crowns shown in  FIGS.  3 - 7    each have a shaft extending through an opening in a housing. In some cases, the shaft may be omitted, or the crown may otherwise have a different configuration and/or integration with the housing.  FIG.  8    illustrates an example electronic device  800  with an optical crown  812  without a shaft. This configuration may have advantages such as easier or faster manufacturing, better environmental sealing, or the like. 
     The device  800  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  800 , and for brevity will not be repeated here. The device  800  may include a crown  812  (which may be an embodiment of the crown  312  or any other crown described herein). The crown  812  may include a head  813 . The crown  812  may include a light-directing feature  826  that directs light from an imaging surface  816  to an image-sensing element  824 , as described above. 
     Instead of an internally mounted image-sensing element, the crown  812  includes an image-sensing element  824  mounted on or otherwise incorporated with the head  813 . For example, the image-sensing element  824  may be adhered to, encapsulated within, or mechanically fastened to the head  313 . In some cases, the image-sensing element  824  may be set into a recess in the head  813 . The light-directing feature  826  may still be configured to direct light from the imaging surface  816  onto the image-sensing element  824 , though the image will not need to pass through a shaft. 
     Conductors  821  (e.g., wires, a flex connector, a conductive trace, or another conductive component) may be coupled to the image-sensing element  824  and may extend through an opening  817  in the housing  802 , where they connect to a processor  820  or other component of an image sensor that analyzes the images received and/or detected by the image-sensing element  824 . 
     In the device  800 , both the head  813  and the image-sensing element  824  are positioned outside of the interior volume of the device housing  802 . This may simplify manufacture of the device  800 . For example, because there is no shaft, the need for precise optical alignment between the shaft and the image-sensing element may be eliminated. Moreover, the mating of the head  813  to the housing  802 , as well as the smaller opening  817  that need only accommodate the conductors  821  (rather than a crown shaft), may allow for better sealing against liquid or other debris. 
     The head  813  may be attached to the housing  802  using adhesive, welding, mechanical fasteners, or the like. Where the head  813  is configured to rotate and/or translate relative to the housing  802 , the head  813  may be attached to the housing  802  with bearings, bushings, guides, or other suitable components. 
       FIG.  9    illustrates an example electronic device  900  with an optical crown  912  with a cover member over an end surface of the crown. The device  900  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  900 , and for brevity will not be repeated here. The device  900  may include a crown  912  (which may be an embodiment of the crown  312  or any other crown described herein). The crown  912  may include a head  913  and a shaft  915 . The crown  912  may include a light-directing feature  926  that directs light from an imaging surface  916  to an image-sensing element  924 , as described above. The device  900  may include a sealing member  920  between the shaft  915  and a housing  902 , and the image-sensing element  924  may be positioned on a support  922 . 
     In  FIG.  9   , the crown  912  also includes a cover member  928  attached to the end of the head  913 . The cover member  928 , which may also resemble and/or be referred to as a cap, may cover and protect the light-directing feature  926 , and may provide a cosmetic exterior surface to the crown  912 . The cover member  928  may be formed of any suitable material, such as plastic, sapphire, metal, gemstones, ceramic, or the like. In cases where the crown  912  includes an axial touch sensing system, as described above, the cover member  928  or a portion thereof may be light-transmissive to allow the axial touch sensing system to operate. The cover member  928  may be attached to the crown  912  in any suitable manner, including welding, adhesives, mechanical fasteners and/or interlocks, soldering, brazing, or the like. The cover member  928 , and more particularly a peripheral surface of the cover member  928 , may be substantially flush with the cylindrical peripheral surface of the head  913 . 
       FIG.  10    illustrates an example electronic device  1000  with an optical crown  1012 . The device  1000  may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100  (or any other wearable device described herein). Accordingly, details of the wearable device  100  described above may apply to the device  1000 , and for brevity will not be repeated here. The device  1000  may include a crown  1012  (which may be an embodiment of the crown  312  or any other crown described herein). The crown  1012  may include a head  1013  and a shaft  1015 . The crown  1012  may include a light-directing feature  1026  that directs light from an imaging surface  1016  to an image-sensing element  1024 , as described above. The device  1000  may include a sealing member  1020  between the shaft  1015  and a housing  1002 , and the image-sensing element  1024  may be positioned on a support  1022 . 
     The device  1000  also includes a force sensing component  1028 . The force sensing component  1028  may be configured to detect axial and/or translational inputs applied to the crown  1012 , as described above. As shown, the force sensing component  1028  is a dome switch, which may provide both an input detection and a tactile output function. For example, when an axial force exceeding a collapse threshold of the dome switch is applied to the crown  1012 , the dome switch may abruptly collapse, which both closes an electrical contact (thereby allowing the device to register the input), and produces a tactile “click” or other tactile output that may be felt by the user. In other cases, the force sensing component  1028  may be a force sensor that is configured to produce an electrical response that corresponds to an amount of force (e.g., axial force) applied to the crown  1012 . The electrical response may increase continuously as the amount of applied force increases, and as such may provide non-binary force sensing. 
     As described above, an imaging surface may be defined along an entire peripheral surface of a crown, or along only a portion of a peripheral surface.  FIGS.  11 A and  11 B  illustrate example crowns in which the imaging surface extends along less than the entire peripheral surface.  FIG.  11 A , for example, shows an example device  1100  (which may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100 ) with a crown  1102 . An imaging surface  1104  may extend along less than the entire peripheral surface of the crown  1102 . As shown, the portion of the crown  1102  that faces or is nearest a user&#39;s wrist when the device is being worn may not be part of the imaging surface  1104 . This may help prevent false inputs from being detected due to movement of the device  1100  relative to the user&#39;s wrist (e.g., as may occur during jostling or other normal use conditions). 
       FIG.  11 B  shows an example device  1110  (which may be an embodiment of the device  100 , and may include the same or similar components and may provide the same or similar functions as the device  100 ) with a crown  1112 . The crown  1112  defines several imaging surfaces, which may also be described as an imaging surface having several discrete segments. For example, an imaging surface  1114  may extend along a top portion of the crown  1112 , while imaging surfaces  1114  and  1118  extend along side portions of the crown  1112 . The crown  1112  may not capture images in the areas between adjacent imaging surfaces. 
     In  FIGS.  11 A- 11 B , the imaging surfaces may be defined by light-transmissive windows set into an otherwise opaque head. For example, windows of glass, plastic, ceramic, sapphire, or other materials may be inset into a head of metal, plastic, or other opaque material. 
       FIG.  12    depicts an example schematic diagram of an electronic device  1200 . By way of example, the device  1200  of  FIG.  12    may correspond to the wearable electronic device  100  shown in  FIGS.  1 A- 1 B  (or any other wearable electronic device described herein). To the extent that multiple functionalities, operations, and structures are disclosed as being part of, incorporated into, or performed by the device  1200 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the device  1200  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. 
     As shown in  FIG.  12   , a device  1200  includes a processing unit  1202  operatively connected to computer memory  1204  and/or computer-readable media  1206 . The processing unit  1202  may be operatively connected to the memory  1204  and computer-readable media  1206  components via an electronic bus or bridge. The processing unit  1202  may include one or more computer processors or microcontrollers that are configured to perform operations in response to computer-readable instructions. The processing unit  1202  may include the central processing unit (CPU) of the device. Additionally or alternatively, the processing unit  1202  may include other processors within the device including application specific integrated chips (ASIC) and other microcontroller devices. 
     The memory  1204  may include a variety of types of non-transitory computer-readable storage media, including, for example, read access memory (RAM), read-only memory (ROM), erasable programmable memory (e.g., EPROM and EEPROM), or flash memory. The memory  1204  is configured to store computer-readable instructions, sensor values, and other persistent software elements. Computer-readable media  1206  also includes a variety of types of non- transitory computer-readable storage media including, for example, a hard-drive storage device, a solid-state storage device, a portable magnetic storage device, or other similar device. The computer-readable media  1206  may also be configured to store computer-readable instructions, sensor values, and other persistent software elements. 
     In this example, the processing unit  1202  is operable to read computer-readable instructions stored on the memory  1204  and/or computer-readable media  1206 . The computer-readable instructions may adapt the processing unit  1202  to perform the operations or functions described above with respect to  FIGS.  1 A- 11 B . In particular, the processing unit  1202 , the memory  1204 , and/or the computer-readable media  1206  may be configured to cooperate with a sensor  1224  (e.g., an image sensor that detects input gestures applied to an imaging surface of a crown) to control the operation of a device in response to an input applied to a crown of a device (e.g., the crown  112 ). The computer-readable instructions may be provided as a computer-program product, software application, or the like. 
     As shown in  FIG.  12   , the device  1200  also includes a display  1208 . The display  1208  may include a liquid-crystal display (LCD), organic light emitting diode (OLED) display, light emitting diode (LED) display, or the like. If the display  1208  is an LCD, the display  1208  may also include a backlight component that can be controlled to provide variable levels of display brightness. If the display  1208  is an OLED or LED type display, the brightness of the display  1208  may be controlled by modifying the electrical signals that are provided to display elements. The display  1208  may correspond to any of the displays shown or described herein. 
     The device  1200  may also include a battery  1209  that is configured to provide electrical power to the components of the device  1200 . The battery  1209  may include one or more power storage cells that are linked together to provide an internal supply of electrical power. The battery  1209  may be operatively coupled to power management circuitry that is configured to provide appropriate voltage and power levels for individual components or groups of components within the device  1200 . The battery  1209 , via power management circuitry, may be configured to receive power from an external source, such as an AC power outlet. The battery  1209  may store received power so that the device  1200  may operate without connection to an external power source for an extended period of time, which may range from several hours to several days. 
     In some embodiments, the device  1200  includes one or more input devices  1210 . An input device  1210  is a device that is configured to receive user input. The one or more input devices  1210  may include, for example, a push button, a touch-activated button, a keyboard, a key pad, or the like (including any combination of these or other components). In some embodiments, the input device  1210  may provide a dedicated or primary function, including, for example, a power button, volume buttons, home buttons, scroll wheels, and camera buttons. Generally, a touch sensor or a force sensor may also be classified as an input device. However, for purposes of this illustrative example, the touch sensor  1220  and a force sensor  1222  are depicted as distinct components within the device  1200 . 
     The device  1200  may also include a sensor  1224  that detects inputs provided by a user to a crown of the device (e.g., the crown  112 ). As described above, the sensor  1224  may include sensing circuitry and other sensing elements that facilitate sensing of gesture inputs applied to an imaging surface of a crown, as well as other types of inputs applied to the crown (e.g., rotational inputs, translational or axial inputs, axial touches, or the like). The sensor  1224  may include an optical sensing element, such as a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS), or the like. The sensor  1224  may correspond to any sensors described herein or that may be used to provide the sensing functions described herein. 
     The device  1200  may also include a touch sensor  1220  that is configured to determine a location of a touch on a touch-sensitive surface of the device  1200  (e.g., an input surface defined by the portion of a cover  108  over a display  109 ). The touch sensor  1220  may use or include capacitive sensors, resistive sensors, surface acoustic wave sensors, piezoelectric sensors, strain gauges, or the like. In some cases, the touch sensor  1220  associated with a touch-sensitive surface of the device  1200  may include a capacitive array of electrodes or nodes that operate in accordance with a mutual-capacitance or self-capacitance scheme. The touch sensor  1220  may be integrated with one or more layers of a display stack (e.g., the display  109 ) to provide the touch-sensing functionality of a touchscreen. Moreover, the touch sensor  1220 , or a portion thereof, may be used to sense motion of a user&#39;s finger as it slides along a surface of a crown, as described herein. 
     The device  1200  may also include a force sensor  1222  that is configured to receive and/or detect force inputs applied to a user input surface of the device  1200  (e.g., the display  109 ). The force sensor  1222  may use or include capacitive sensors, resistive sensors, surface acoustic wave sensors, piezoelectric sensors, strain gauges, or the like. In some cases, the force sensor  1222  may include or be coupled to capacitive sensing elements that facilitate the detection of changes in relative positions of the components of the force sensor (e.g., deflections caused by a force input). The force sensor  1222  may be integrated with one or more layers of a display stack (e.g., the display  109 ) to provide force-sensing functionality of a touchscreen. 
     The device  1200  may also include a communication port  1228  that is configured to transmit and/or receive signals or electrical communication from an external or separate device. The communication port  1228  may be configured to couple to an external device via a cable, adaptor, or other type of electrical connector. In some embodiments, the communication port  1228  may be used to couple the device  1200  to an accessory, including a dock or case, a stylus or other input device, smart cover, smart stand, keyboard, or other device configured to send and/or receive electrical signals. 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources to facilitate the detection of inputs to an electronic device. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include biometric data (e.g., fingerprints), demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, users can deactivate input detection using imaging techniques that may capture or use biometric information (e.g., fingerprints, skin features, etc.). In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, gesture inputs applied to a crown with an object other than a finger, or with a gloved finger, may be operable to control the operation of an electronic device. Further, the functionality described herein may be provide without requiring any persistent storage of personal information. For example, images of a user&#39;s finger that are captured by an image sensor may be analyzed and then discarded immediately after the necessary motion information has been determined. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. Also, when used herein to refer to positions of components, the terms above and below, or their synonyms, do not necessarily refer to an absolute position relative to an external reference, but instead refer to the relative position of components with reference to the figures.