PATENT DOCUMENT

Publication Number: US-10962935-B1
Application Number: US-201815879223-A
Country: US
Kind Code: B1

Title: Tri-axis force sensor

Abstract:
An input device includes a movable input surface protruding from an electronic device. The input device enables force inputs along three axes relative to the electronic device: first lateral movements, second lateral movements, and axial movements. The input device includes force or displacement sensors which can detect a direction and magnitude of input forces.

Claims:
What is claimed is: 
     
       1. A watch, comprising:
 a housing; 
 a display at least partially within the housing; 
 a crown, comprising:
 a stud coupled to the housing and protruding from the housing; 
 a crown cap coupled to the stud; 
 a compliant material surrounding at least a portion of the stud and at least partially surrounded by the crown cap, the compliant material configured to deform in response to a movement of the crown cap relative to the stud caused by an input provided to the crown cap; 
 a force sensor positioned between the stud and the crown cap and configured to provide a signal in response to a deformation of the compliant material caused by the input; and 
 
 a processor coupled to the force sensor and configured to determine a force associated with the input based on the signal; wherein:
 the stud defines an opening; and 
 the opening facilitates an electrical connection between the processor and the force sensor. 
 
 
     
     
       2. The watch of  claim 1 , wherein:
 the watch further comprises a position sensor configured to detect rotation of the crown cap; 
 the force sensor comprises:
 a first electrode; 
 a second electrode; 
 a third electrode; 
 a fourth electrode; and 
 an insulating substrate between the first electrode and the second electrode, and between the third electrode and fourth electrode; 
 
 the force sensor is configured to detect lateral movement of the crown cap based on a change in capacitance between the first electrode and the second electrode; 
 the force sensor is further configured to detect axial movement of the crown cap based on a change in capacitance between the third electrode and the fourth electrode; 
 the display is configured to display one or more indicia; and 
 the display is configured to change the one or more indicia in response to the rotation, the lateral movement, or the axial movement of the crown cap. 
 
     
     
       3. The watch of  claim 1 , further comprising:
 a flexible circuit positioned within the opening and extending from within the housing to the force sensor; wherein 
 the flexible circuit comprises the electrical connection that electrically couples the processor to the force sensor. 
 
     
     
       4. The watch of  claim 1 , wherein:
 the stud comprises a rotatable shaft; and 
 the crown further comprises a positional sensor configured to detect an amount of rotation of the rotatable shaft. 
 
     
     
       5. The watch of  claim 1 , wherein:
 the stud comprises:
 a threaded portion configured to engage with the housing; 
 a protruding portion at least partially surrounded by the compliant material; and 
 a flange around the stud and positioned between the threaded portion and the protruding portion; 
 
 the threaded portion defines a hollow internal portion which facilitates the electrical connection. 
 
     
     
       6. The watch of  claim 5 , further comprising:
 a fastener threadedly engaged with the stud and rigidly coupling the stud to the housing. 
 
     
     
       7. The watch of  claim 1 , wherein:
 the crown cap is rotatable; and 
 a positional sensor is coupled to the stud and configured to detect an amount of rotation of the crown cap. 
 
     
     
       8. A watch crown, comprising:
 a stud configured to couple to a housing of an electronic device thereby defining a protruding portion when coupled to the housing; 
 a compliant material surrounding at least a portion of the protruding portion of the stud; 
 a crown cap defining a recess, at least a portion of the compliant material positioned in the recess, the compliant material configured to deform in response to a movement of the crown cap relative to the stud; 
 a first sensor configured to transmit a first signal in response to the movement of the crown cap relative to the stud; 
 a second sensor configured to transmit a second signal in response to the movement of the crown cap relative to the stud; and 
 a processor coupled to the first sensor and the second sensor and configured to correlate the first signal and the second signal to an input. 
 
     
     
       9. The watch crown of  claim 8 , further comprising:
 a circuit coupled to the first sensor and the second sensor, the circuit passing through and opening in the stud. 
 
     
     
       10. The watch crown of  claim 9 , wherein the compliant material at least partially fills the stud and encompasses the circuit. 
     
     
       11. The watch crown of  claim 9 , wherein the first sensor and the second sensor comprise:
 an insulating substrate; 
 a flexible drive circuit coupled to a first surface of the insulating substrate; and 
 a flexible sense circuit coupled to a second surface of the insulating substrate opposite the first surface. 
 
     
     
       12. The watch crown of  claim 11 , wherein the insulating substrate, the flexible drive circuit, and the flexible sense circuit form a ring around an end of the stud. 
     
     
       13. The watch crown of  claim 8 , wherein the compliant material facilitates less than complete rotation of the crown cap relative to the stud. 
     
     
       14. The watch crown of  claim 13 , further comprising a position sensor configured to transmit a third signal in response to rotation of the crown cap relative to the stud. 
     
     
       15. An electronic watch comprising:
 a housing; 
 a watch crown coupled to the housing and configured to receive a force input, the watch crown comprising:
 a stud having a protruding portion that extends outward from the housing; 
 a crown cap coupled to the stud and defining a recess; 
 a compliant material surrounding at least a portion of the stud and positioned at least partially in the recess, the compliant material configured to deform in response to a movement of the crown cap relative to the stud caused by the force input; 
 
 a first force sensor configured to detect a first component of the force input along a first direction; 
 a second force sensor configured to detect a second component of the force input along a second direction different from the first direction; and 
 a processing unit configured to, in response to the force input received at the watch crown:
 determine a first force value using a first output from the first force sensor; 
 determine a second force value using a second output from the second force sensor; and 
 determine, using the first force value and the second force value, an input direction of the force input. 
 
 
     
     
       16. The electronic watch of  claim 15 , wherein the processing unit is further configured to determine, using the first force value and the second force value, that the force input corresponds to one or more of a lateral input or a rotational input. 
     
     
       17. The electronic watch of  claim 15 , wherein the processing unit is further configured to:
 determine, using the first force value and the second force value, that the force input is unintended; and 
 in response to determining that the force input is unintended, reject the force input. 
 
     
     
       18. The electronic watch of  claim 15 , wherein:
 the electronic watch further comprises a display; and 
 the processing unit is further configured to, in response to determining the input direction of the force input, modify at least one of an indicium displayed on the display or a brightness of the display according to the input direction of the force input. 
 
     
     
       19. The electronic watch of  claim 15 , further comprising a positional sensor configured to detect a change in a rotational position of the watch crown. 
     
     
       20. The electronic watch of  claim 19 , wherein the processing unit is further configured to, in response to the change in the rotational position of the watch crown exceeding a threshold, modify an indicium on a display of the electronic watch.

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. 62/533,994, filed Jul. 18, 2017 and titled “Tri-Axis Force Sensor,” the disclosure of which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     The described embodiments relate generally to input devices. More particularly, the present embodiments relate to multi-axial pressure input devices, such as a watch crown, coupled to electronic devices. 
     BACKGROUND 
     Many devices, such as wearable electronic devices, use various input mechanisms to receive user input. In particular, small form factor devices, such as watches, smart watches, wearable devices, and so on, may have a limited number of input mechanisms. 
     For example, many watches include a crown or similar input mechanism. Some crowns can be rotated to wind the watch. Other crowns may be translated into a time-changing position whereupon they may be rotated to change the time of the watch. 
     SUMMARY 
     The present disclosure relates to an input mechanism, such as a watch crown, that detects applied force along multiple axes. The input mechanism may be included in an electronic device. A user may provide input to the electronic device by applying force axially (e.g., along an axis of rotation of the input mechanism), laterally (e.g., perpendicular to the axis of rotation), or rotationally (e.g., rotating about the axis of rotation). The input mechanism may include two or more force sensors that may be used to determine a magnitude and direction of a force applied to the watch crown. The electronic device may be used to receive a variety of different inputs based on various directions and magnitudes of force applied to the watch crown. 
     A watch may include a housing, a display at least partially within the housing, a crown, and a processor. The crown includes a stud coupled to, and protruding from, the housing of the watch. A compliant material surrounds at least a portion of the stud, and a crown cap at least partially surrounds the compliant material. A force sensor is positioned within the compliant material, and the processor is coupled to the force sensor. The stud also defines an opening which facilitates an electrical connection between the processor and the force sensor. 
     In some examples, the force sensor includes a first electrode, a second electrode, and an insulating substrate between the first electrode and the second electrode. The force sensor is configured to detect a movement of the crown cap based on a change in distance between the first electrode and the second electrode. 
     An input device may include a stud configured to couple to, and protrude from, an electronic device, a compliant material surrounding at least a portion of the stud, and a crown cap at least partially surrounding the compliant material. The crown cap is configured to move relative to the stud. A first sensor is configured to transmit a first signal in response to the movement of the cap relative to the stud, and a second sensor is configured to transmit a second signal in response to the movement of the cap relative to the stud. A processor is coupled to the first sensor and the second sensor, and the processor is configured to correlate the first signal and the second signal to an input. 
     A method of detecting a force applied to a crown of a watch includes the operation of detecting a movement of the crown relative to the watch in response to application of the force using a first force sensor and a second force sensor. A first force value is determined which correlates to the first force sensor, and a second force value is determined which correlates to the second force sensor. The first force value and the second force value are compared to a stored input profile to determine a direction of an input to the crown. 
    
    
     
       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 elements. 
         FIG. 1  depicts an electronic device in the form of an electronic watch, incorporating an example watch crown according to the present disclosure. 
         FIG. 2  depicts a cross-section of an example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . 
         FIG. 3  depicts a sample cross-section of a watch crown, illustrating a stud and a force sensor. 
         FIG. 4A  depicts a sample cross-section of the watch crown at a first position, in which no force is applied to the crown cap. 
         FIG. 4B  depicts the watch crown in a second position, in response to a user&#39;s application of an axial force to the crown cap. 
         FIG. 4C  depicts the watch crown in a third position, in response to a user&#39;s application of a lateral force to the crown cap. 
         FIG. 4D  depicts the watch crown in a fourth position, in response to a user&#39;s application of an oblique force to the crown cap. 
         FIG. 4E  depicts the watch crown in a fifth position, in response to a rotation of the crown cap. 
         FIG. 5A  depicts a sample cross-section of the watch crown, with certain elements removed to better illustrate a force sensor. 
         FIG. 5B  depicts a sample cross-section of the watch crown, with certain elements removed to better illustrate a second example of a force sensor. 
         FIG. 5C  depicts a sample cross-section of the watch crown, with certain elements removed to better illustrate a third example of a force sensor. 
         FIG. 6  depicts a cross-section of another example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . 
         FIG. 7  depicts a cross-section of another example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . 
         FIG. 8  depicts a cross-section of another example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . 
         FIG. 9A  depicts an example electronic device having a watch crown and a display depicting example graphics. 
         FIG. 9B  depicts the electronic device of  FIG. 9A , illustrating how the graphics shown on the display change as the watch crown rotates. 
         FIG. 10A  depicts an example electronic device with a display depicting another example of a graphic. 
         FIG. 10B  depicts the electronic device of  FIG. 10A , illustrating an example zoom operation in response to application of force to the crown. 
         FIG. 11A  depicts an example electronic device with a display depicting another example of a graphic. 
         FIG. 11B  depicts the electronic device of  FIG. 11A , illustrating using the watch crown to change an operational state of the electronic device or otherwise toggle between inputs. 
         FIG. 12  depicts a schematic representation of example components of an electronic device. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     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 implementation. To the contrary, the described embodiments are intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the disclosure and as defined by the appended claims. 
     An electronic device is disclosed herein, which may facilitate interaction with a user. The electronic device may be a wearable device, such as a watch, and may include a touch screen operative to receive inputs from a user. The watch may include a crown as an additional input mechanism capable of receiving multi-directional input from the user. Generally, the crown is coupled to a housing of the watch at a location similar to a traditional mechanical watch. 
     The crown may receive force or displacement input from a user along three axes relative to its attachment point on a side of the watch housing when the device is in use: x (e.g., in a first lateral direction, relative to the housing), y (e.g., in a second lateral direction, relative to the housing), and z (e.g., into or out of the housing) (see, e.g.,  FIG. 2 ). The crown may receive rotational force or displacement input as well (e.g., rotating about the z axis shown in  FIG. 2 ). Force or displacement sensors may be included within the crown and/or watch housing to detect force inputs. Generally, force inputs to the crown may cause a displacement of the crown (or a portion of the crown), and may accordingly be detected by force or displacement sensors. One or more sensors may enable the watch to distinguish a degree and/or direction of an input to the crown. These or additional sensors may further detect rotational input to the crown. 
     A traditional watch crown may detect only rotation of the crown as an input. The tri-axial crown of the present disclosure enables additional input to the crown, such as pressing the crown as a button, moving the crown up and down to scroll through options, moving the crown back and forth to adjust a volume or brightness level of the watch, or otherwise changing an indicium (or indicia) on a display of the electronic device. As used herein, an “indicium” is any text, graphic, icon, symbol, or the like, Sample indicia include application icons, volume indicators, brightness indicators, data shown in a list, power indicators, words, numbers, and so on. “Indicia” is the plural of “indicium.” 
     In some embodiments, these additional inputs may further enable intelligent processing of detected forces applied to the crown. For example, a motion of a wearer&#39;s wrist may be falsely detected as a deliberate crown input (e.g., a press). A processor in communication with the crown may determine such motion is unintentional. Accordingly, the processor may reject (or ignore) the detected force, rather than processing it as an input to the device. 
     An example tri-axial watch crown may include a stud or shaft which attaches to, and protrudes outward from, the housing. A crown cap may be attached to the stud in order to provide a surface through which a user interacts with the crown. A compliant material may be disposed between the crown cap and the stud, facilitating motion of the cap relative to the stud in the x, y, and z directions. 
     A force or displacement sensor may be placed within, or in contact with, the compliant material. Thus, if a user presses on the crown cap, the compliant material may be compressed or otherwise deformed, causing the sensor to detect a motion of the crown cap relative to the stud. The sensor may include a series of displacement or force sensors arranged within the compliant material in such a way as to allow a processing unit to distinguish motions along the x-, y- and z-axes, or any combination thereof. The processing unit may additionally correlate the detected forces to an input to the electronic device. 
     In other examples, the compliant material may be omitted and/or the sensors may be in different locations. For example, a shaft may pass into the housing. Sensors may be arranged around the shaft and within the housing such that the sensors may detect motion of the shaft relative to the housing. 
     In many embodiments, the crown may be rotatable. Rotation of the crown may be detectable by the same or additional sensors as those which detect force applied to the crown. For example, the crown may include a shaft which may rotate relative to the housing of the watch. Sensors may detect this rotation of the shaft relative to the housing. In other examples, the crown may include a stud rigidly attached to the housing and a crown cap may rotate around the stud. Sensors within the crown cap and/or stud may detect the rotation of the crown cap. 
     In still other examples, the crown cap or shaft may only partially rotate. For example, a compliant material between a stud and a watch crown may facilitate less than complete rotation of the crown relative to the stud. The rotation may compress the compliant material, and force sensors may detect a rotational force. The degree of rotation may be determined based on the amount of force detected by the force sensors. 
     These and other embodiments are discussed below with reference to  FIGS. 1-9 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  depicts an electronic device in the form of a touch-enabled watch, incorporating an example watch crown according to the present disclosure. The electronic device  100  includes a housing  108  surrounding a touch-enabled display  106 . The display  106  may be configured to display indicia to a user and receive touch inputs. The electronic device may be operable to receive additional input from a user, such as through a button  104 . 
     The electronic device  100  may also be operable to perform various actions in response to input received via a watch crown  102  or similar input structure. The watch crown  102  may receive inputs along three axes, such that it may move laterally with respect to the housing  108  in multiple directions, axially with respect to the housing (e.g., toward or away from the housing), and/or rotationally. In some embodiments, the watch crown  102  may further receive rotational inputs. Example embodiments of the watch crown  102  and its operation are further described below with respect to  FIGS. 2-8 . 
     The electronic device  100  may detect and distinguish various directional force inputs to the watch crown  102 . The electronic device  100  may further detect, estimate, or otherwise measure an amount of the force applied to the watch crown  102 . The electronic device  100  may include a processing unit, a memory, and other components, such as described with respect to  FIG. 9 , to facilitate detecting, processing and responding to inputs received by the watch crown  102 . 
     A compressible seal or structure (examples of which are shown in  FIGS. 2 and 6-8 ) may be positioned between the watch crown  102  and the housing  108  and resist passage of contaminants into internal portions of the watch crown  102  and/or the electronic device  100 . Portions of the compressible seal may collapse and/or bend to allow translational movement of the watch crown  102 . The compressible seal may be configured to obscure and/or otherwise block from view internal components of the watch crown  102  and/or the electronic device  100 . Such a configuration may further allow use of internal components formed of different materials and/or with different surfaces than the housing  108  and/or external portions of the watch crown  102  while preventing the internal components from being visible from outside the housing  108 . 
     The electronic device  100  is shown in  FIG. 1  as a wearable electronic device having a touch-enabled display  106 . However, it is understood that this is an example. In various implementations, the electronic device may be any kind of electronic device that utilizes a tri-axial input mechanism such as the watch crown  102 . Sample electronic devices include a laptop computer, a desktop computer, a mobile computer, a smart phone, a tablet computer, a fitness monitor, a personal media player, a display, audiovisual equipment, and so on. 
       FIG. 2  depicts a cross-section of an example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . The watch crown  202  may be an input device which includes a stud  212  (e.g., a shaft) which couples to the housing  208  of the electronic device. The stud  212  also protrudes outward from the housing  208 . In some embodiments, the stud  212  is formed from a rigid material, such as metal (e.g., aluminum, steel, copper, brass, etc.), plastic, glass, acrylic, ceramic, composites, other materials, or combinations of materials. 
     The stud  212  may couple to a crown cap  210  (e.g., a cap). The crown cap  210  may provide an input surface for user interaction. For example, the watch crown  202  may displace in three directions: along the x-axis; along the y-axis; and along an axis of rotation defined by the z-axis. Displacement along the x or y axes is referred to as “lateral movement,” insofar as the watch crown  202  moves laterally with respect to the housing  208 . Displacement along the z axis is referred to as “axial movement,” encompassing the watch crown  202  moving toward or away from the housing  208 . In some embodiments, the watch crown  202  may further receive rotational inputs via the crown cap  210 . 
     The watch crown  202  may further include a sensor to detect and distinguish forces applied to the crown cap  210  and/or displacement of the crown cap  210  relative to the stud  212 . For example, one or more capacitive force sensors may be formed using an insulating substrate  220  between a flexible drive circuit  216  and a parallel flexible sense circuit  218 . In certain embodiments, the flexible drive circuit  216  is coupled to a surface of the insulating substrate  220 , and the flexible sense circuit  218  is coupled to an opposite surface of the insulating substrate  220 . An electrode may be formed in the flexible drive circuit  216  with a matching electrode formed in the flexible sense circuit  218 . A capacitance may be formed across the matched pair of electrodes, and as force is applied to the crown cap  210 , the insulating substrate  220  between the electrodes may be compressed, resulting in a change in capacitance across the electrodes. A processing unit may determine an amount of force (generally from one or more force values) applied to the crown cap  210  based on this change in capacitance detected by the force sensor. 
     A “force value” may be an amount of force, or may be a component (such as a vector) of a force input, detected by a force sensor. Typically, an embodiment may contain multiple force sensors, and different force sensors may detect different force values. For example, one force sensor may detect a force value along an x axis, while another force sensor may detect a force value along a y axis, and yet another force sensor may detect a force value along a z axis. The various force values may be analyzed by a processor to determine, estimate, correlate, or otherwise arrive at a force input applied to the watch crown  202 , and typically the crown cap  210 . Force values may be detected by any suitable force sensor and need not be vectors of a force input, although this can be the case in many embodiments. 
     The flexible drive circuit  216  and the flexible sense circuit  218  may be formed as a flexible printed circuit board or a similar structure. A flexible printed circuit board may include a flexible substrate formed from a suitable material, such as polyimide or polyethylene terephthalate. The flexible printed circuit board may further include conductive material formed as one or more electrodes and one or more wires, traces, or similar conducting paths. The conductive material may include materials such as silver, copper, gold, constantan, karma, isoelastic materials, indium tin oxide, or any combination thereof. 
     The insulating substrate  220  may be an electrically insulating substrate, such as a dielectric. The insulating substrate  220  may be formed from a compressible material, such as a compliant foam, a silicone gel, and similar materials. The flexible drive circuit  216  and the flexible sense circuit  218  may be coupled to the insulating substrate  220  through an adhesive (e.g., a pressure sensitive adhesive) or similar technique. 
     The flexible drive circuit  216  and flexible sense circuit  218  may include multiple sets of electrodes forming multiple force sensors. With two or more force sensors implemented, the processing unit may detect and distinguish between forces applied along the three different axes, as discussed further below with respect to  FIGS. 5A-5C . 
     In certain embodiments, the stud  212  is coupled to the housing  208  by a fastener  222  (e.g., a clip, threaded nut, or similar fastener) which may hold the stud  212  rigid with respect to the housing  208  along the x-, y-, and z-axes. The fastener  222  may encircle the stud  212  and may additionally threadedly engage the stud  212 . Generally, the stud  212  is coupled in a manner that prevents rotation about the z-axis. 
     The flexible drive circuit  216 , flexible sense circuit  218 , and insulating substrate  220  may be placed between the stud  212  and the crown cap  210 , and surrounded by a compliant material  214 . The compliant material  214  may facilitate movement of the crown cap  210  relative to the stud  212  under an exerted force, while providing a restoring force to return the crown cap  210  once the force is released. In addition, the compliant material  214  may facilitate compression of the insulating substrate  220 , in order to transmit an applied force to the flexible drive circuit  216  and flexible sense circuit  218 . 
     The compliant material  214  may be formed from a suitable material, such as silicone, polyurethane, polyvinylchloride, rubber, fluoroelastomer, another polymer, or similar material. The compliant material  214  may be injection molded to the stud  212  and/or the crown cap  210 , or may be bonded to the stud  212  and the crown cap  210  in another suitable manner. 
     In some embodiments, the watch crown  202  may prevent or reduce entry of water, dust, or other contaminants to the housing  208 . Accordingly, a gasket  228  (such as a silicone or a rubber gasket) may be coupled to the crown cap  210  or the housing  208  at the edge of the crown cap  210  to prevent entry of contaminants. A lubricant  226  (e.g., electrical grease, silicone gel, or similar material) may further prevent entry of contaminants to the housing  208 . Each of the gasket  228  and the lubricant  226  may allow the crown cap  210  to displace relative to the stud  212 , while resisting the entry of contaminants between the housing  208  and the crown cap  210 . 
     Additionally, a pressure seal may be formed between the stud  212  and the housing  208  to further prevent liquid or other contaminants from entering the housing  208 . The stud  212  and/or housing  208  may include a depression to house an O-ring  224  (or similar water sealing element) to provide the pressure seal, resisting the entry of liquids or other contaminants even under pressure. 
     As depicted in  FIG. 2 , the stud  212  may be at least partially hollow. The hollow portion of the stud  212  may provide a path to route the flexible drive circuit  216  and the flexible sense circuit  218  from the region between the stud  212  and the crown cap  210  to within the housing  208 . An opening  217  may be defined in the stud through which the flexible drive circuit  216  and the flexible sense circuit  218  may be routed from the region between the stud  212  and the crown cap  210  to the hollow portion of the stud  212 . The opening  217  and the hollow portion of the stud  212  may typically be filled with the same compliant material  214 , sealing the crown cap  210  to the stud  212 , as well as sealing the hollow portion of the stud  212 , which may also prevent or reduce entry of contaminants to the housing. 
     The opening  217  may facilitate an electrical connection between one or more force sensors and a processing unit within the housing  208 . For example, the flexible drive circuit  216  and the flexible sense circuit  218  may include conductive material (e.g., wires, conductive traces) which forms an electrical connection to force sensors. The flexible drive circuit  216  and flexible sense circuit  218  may also be electrically connected to the processing unit (e.g., directly or by connecting to electrical circuitry connecting to the processing unit). 
     In many embodiments, the opening  217  may be positioned on a side adjacent an end of the stud  212 , which may facilitate sealing with the compliant material  214  surrounding the stud  212 . In other embodiments, the opening  217  may be positioned differently, such as at the end of the stud  212  of further from the end. The opening  217  may be formed in an appropriate shape, such as a round opening, a rectangular opening, or another geometric shape (including a non-regular geometric shape). The cross-section of the opening  217  may change in size and/or shape along the wall of the stud  212 , or it may have a regular size and/or shape. In some examples, more than one opening may be defined in the stud  212  (e.g., to facilitate connection of additional sensors to the processing unit). 
       FIG. 3  depicts a partial cross-section of a watch crown (e.g., input device), similar to the depiction in  FIG. 2 , illustrating only a stud and one or more force sensors, while omitting other components of the watch crown, such as the crown cap  210  and compliant material  214  depicted in  FIG. 2 . As discussed above with respect to  FIG. 2 , in some embodiments the stud  312  is rigid, formed from a metal, plastic, ceramic, or similar material. The stud  312  may be formed with a threaded internal portion  311  and a protruding portion  313  separated by a flange  315 . The flange  315  may define a depression (e.g., an annular or partial groove) to house an O-ring (such as O-ring  224 , depicted in  FIG. 2 ) adjacent the internal portion  311 . 
     The internal portion  311  of the stud  312  may be hollow, to provide a path to route the flexible drive circuit  316  and the flexible sense circuit  318  from the region between the stud  312  and the crown cap to within the housing (e.g., to be electrically coupled to a processing unit or other circuitry). In many embodiments, an opening  317 , such as an aperture, is formed through the protruding portion  313  of the stud  312  adjacent the flange  315 , through which the flexible drive circuit  316  and the flexible sense circuit  318  may pass from the region between the stud  312  and the crown cap into the hollow internal portion  311  of the stud  312 . 
     The flexible drive circuit  316  and the flexible sense circuit  318  may form multiple force sensing pixels (pairs of capacitive electrodes) around the protruding portion  313  of the stud  312  (such as further depicted below with respect to  FIGS. 5A-5C ). The flexible drive circuit  316  and/or the flexible sense circuit  318  may be shaped in a C-shape along the protruding portion  313  as depicted, or each may form a ring or partial ring around the protruding portion  313 . 
     In some embodiments, the flexible sense circuit  318  may be coupled to the protruding portion  313  of the stud  312  by an adhesive (e.g., a pressure sensitive adhesive) or similar technique. The stud  312  may accordingly provide a resistive force against compression of the insulating substrate  320  through coupling across the flexible sense circuit  318 . In other embodiments, the flexible sense circuit  318  may not be coupled to the stud  312 , but the flexible drive circuit  316  and the flexible sense circuit  318  may instead be surrounded (e.g., encompassed) by a compliant material (such as the compliant material  214  depicted in  FIG. 2 ). 
     Turning to  FIGS. 4A-4D , the operation of the flexible drive circuit and the flexible sense circuit is further illustrated as force is applied to the crown cap.  FIGS. 4A-4D  depict sample cross-sections of the watch crown  402 , similar to the depiction in  FIG. 2 , illustrating the stud  412 , the crown cap  410 , and one or more force sensors formed by the flexible drive circuit  416  and the flexible sense circuit  418  coupled to the insulating substrate  420 . Additional components, such as a compliant material between the crown cap  410  and the stud  412 , are omitted for clarity. 
       FIG. 4A  illustrates the watch crown  402  at a first position (e.g., a resting position), in which no force is applied to the crown cap  410 . Compliant material  414  is positioned between the crown cap  410  and the stud  412 . The compliant material  414  facilitates displacement of the crown cap  410  when a force is applied, while providing a restoring force to return the crown cap  410  to its resting position when the force is released, and generally has the same properties and function as compliant material  214  described above with respect to  FIG. 2 . 
       FIG. 4B  depicts the watch crown  402  in a second position, in response to a user&#39;s application of an axial force F (e.g., a force along the z-axis) to the crown cap  410 . The applied force F may compress the compliant material  414  positioned around point A (e.g., along the end of the stud  412  adjacent the crown cap  410 ). This compression of the substrate in turn causes the insulating substrate  420  (e.g., electrically insulating substrate) to compress around point A. As the insulating substrate  420  around point A is compressed, the flexible sense circuit  418  and the flexible drive circuit  416  move closer together at point A, and a force sensor  434  detects the compressive force. 
     A processing unit may determine, based on the force detected by the force sensor  434 , that the crown cap  410  has moved along the z-axis (e.g., by comparing the force detected by the force sensor  434  with other force sensors in the flexible drive circuit  416  and the flexible sense circuit  418 ). The processing unit may further correlate or otherwise associate the force detected with a particular type of input. For example, the axial motion of  FIG. 4C  may be correlated with a button input, such as selection of an item or the start of a timer. The amount of compressive force F applied along the z-axis may also be detected, and different inputs may correspond to varying amounts of force (e.g., force values) detected by the force sensor  434 . 
     In another example, a user may apply a lateral force F (e.g., a force along the y-axis) to the crown cap  410 , as depicted in  FIG. 4C . The force F may cause the crown cap  410  to move downward relative to the stud  412 , compressing the compliant material  414  around point B and placing the compliant material around point C in tension. This may in turn compress the insulating substrate  420  around point B and place the insulating substrate  420  around point C in tension. 
     In response, the flexible sense circuit  418  and the flexible drive circuit  416  move closer together at point B, and a force sensor  436  detects the compressive force. In addition, the flexible sense circuit  418  and the flexible drive circuit  416  move apart at point C, and a force sensor  438  detects the tension. 
     In another example, as depicted in  FIG. 4D , a user may apply a force F to the crown cap  410  at an oblique angle (e.g., an angle which is along a direction between a lateral and axial direction). The force F may cause the crown cap  410  to tilt, compressing the compliant material  414  around point D and placing the compliant material around point E in tension. 
     In some embodiments, the material properties of the compliant material  414  may cause the crown cap  410  to tilt rather than translate along the y-axis in response to a lateral force F′. For example, the compliant material  414  may resist compression immediately above the stud  412 , while allowing compression within the compliant material  414  around point D (e.g., adjacent the end of the stud  412 ). Thus, the compressive force applied along the y-axis may be transferred to compress the compliant material  414  around point D while placing the compliant material  414  around point E in tension. Accordingly, the crown cap  410  may tilt rather than translate laterally in response to force along the y-axis. 
     As the compliant material  414  around point D compresses, the insulating substrate  420  around point D is also compressed. As the insulating substrate  420  around point D is compressed, the flexible sense circuit  418  and the flexible drive circuit  416  move closer together at point D, and a first force sensor  432  detects the compressive force. 
     Simultaneous with the compression around point D, the compliant material around point D may expand (e.g., be placed under tension), placing the insulating substrate  420  in tension. As the insulating substrate  420  around point D is placed in tension, the flexible sense circuit  418  and the flexible drive circuit  416  move apart at point D, and a second force sensor  430  detects the tension. 
     The processing unit may compare the compressive force detected by the first force sensor  432  and the tension detected by the second force sensor  430  to determine that the crown cap  410  has tilted with respect to the stud  412 . The processing unit may further determine the relative amounts of force (e.g., after determining force values corresponding to each respective force sensor  430 ,  432 ) or tension measured by the first force sensor  432  and the second force sensor  430  to determine a profile of the type of force applied to the crown cap  410 . 
     Turning to  FIG. 4E , a rotation of the watch crown  402  may be detected, even in embodiments in which the stud  412  is coupled to the watch housing in a manner that prevents rotation of the stud  412 . In such embodiments the crown cap  410  may be partially rotatable with respect to the stud  412 . For example, the compliant material  414  between the crown cap  410  and the stud  412  may allow some, but not complete, rotation of the crown cap  410  about the stud  412 . 
     A user may apply a rotational force F (e.g., a force involving a revolution about the z-axis) to the crown cap  410 , which causes the compliant material  414  to deform in shear about the z-axis. For example, the compliant material  414  around point B and around point C may be placed under tension and/or compression. As the compliant material  414  deforms, the flexible drive circuit  416  around points B and C may translate about the z-axis relative to the flexible sense circuit  418 . Accordingly, a pair of electrodes in the force sensor  436  at the top of the stud  412  may translate away from each other about the Z-axis, causing a change in capacitance to be measured by the force sensor  436 . Another pair of electrodes in the force sensor  438  at the bottom of the stud may translate along the same rotational direction, causing a change in capacitance to be measured by the force sensor  438 . 
     The processing unit may compare the rotational force detected by the force sensor  436  at the top of the stud  412  with the rotational force detected by the force sensor  438  at the bottom of the stud  412  to determine that the crown cap  410  has rotated in a particular direction (e.g., clockwise or counter-clockwise) with respect to the stud  412 . For example, the electrodes of the force sensor  436  at the top of the stud  412  may be offset such that a clockwise rotation increases the capacitance of the force sensor  436  (due to bringing more of the electrodes in parallel) and a counter-clockwise rotation decreases capacitance of the force sensor  436  (due to separating the electrodes). In some examples, changes in other force sensors may also be analyzed to distinguish a rotation from a lateral force or other input. The processing unit may further determine an amount of rotational force applied to the crown cap  410 , which may be interpreted as an intended degree of input rotation. 
     In some examples, the force sensors  430 ,  432 ,  434 ,  436 ,  438  may detect force inputs along more than one of the x-, y-, and z-axes. The processor may analyze multiple force sensing signals to determine the directions and amounts of such multi-axial forces. The processor may further compare these force sensing signals to input profiles or otherwise determine an intended type of input to the watch crown  402 . For example, the electronic device may be a watch on a user&#39;s wrist. In such an embodiment, accidental button presses may occur as a user&#39;s wrist moves. The processing unit may receive, from one or more force sensors, force inputs along both the y-axis and the z-axis, or as a tilt similar to  FIG. 4D . The processing unit may further determine (e.g., by comparing the force inputs to an input profile or the like) that such an input is unintended, and reject it as a user input. As one example, if the watch crown  402  tilts, the input may be rejected. 
     In many embodiments, the processing unit may distinguish between the various movements of the watch crown  402  initiated in response to user force. The processing unit may further interpret (e.g., correlate) the movements as distinct inputs for different operations of the electronic device. For example, a first lateral movement (movement along the y-axis) may adjust a brightness or volume associated with the electronic device, while a second lateral movement (movement along the x-axis) may switch the device between a silent mode and an alert mode. 
     A rotational movement (movement about the z-axis) may cause the electronic device to scroll between a list of available software application for selection, while an axial movement (movement along the z-axis) may select the software application or start a timer. In addition, movements along multiple directions may be processed differently. Force inputs may be compared with one or more force profiles, which may correspond to a particular type of input to the crown cap  410 . For example, the lateral force input of  FIG. 4C  may be treated as a volume change, the rotational input of  FIG. 4E  may change a graphical display (e.g., by moving a selection indicator), the axial force input of  FIG. 4B  is treated as a selection, and the tilt input of  FIG. 4D  is treated as a display brightness change. 
     It should be understood that the various inputs are adaptable to user preferences and context, and the above examples are illustrative in nature. For example, the electronic device may operate various software applications, and how each type of watch crown  402  movement may be interpreted may be based on an active software application. Generally, the examples given herein are but some sample ways in which an input to the crown may change an indicium (or indicia) displayed by the electronic device. As used herein, an “indicium” is any text, graphic, icon, symbol, or the like, Sample indicia include application icons, volume indicators, brightness indicators, data shown in a list, power indicators, words, numbers, and so on. “Indicia” is the plural of “indicium.” 
       FIGS. 5A-5C  depict various potential arrangements for capacitive electrodes (e.g., force sensors) for sensing forces applied to a watch crown. The capacitive electrodes  516   a - 516   j ,  518   a - 518   j  may be formed on or within flexible circuits (such as flexible drive circuit  216  and flexible sense circuit  218  as depicted in  FIG. 2 ), and are shown in  FIGS. 5A-5C  without such encapsulation for illustrative purposes. Likewise,  FIGS. 5A-5C  omit compliant material, such as compliant material  214  depicted in  FIG. 2 , for clarity. 
     As discussed above, amounts of force applied to the watch crown  502  may be detected by one or more force sensors positioned between the crown cap  510  and the stud  512 . The force sensors may be formed from one or more matched pairs of capacitive electrodes  516   a - 516   j ,  518   a - 518   j  coupled to an insulating substrate (such insulating substrate  220  as depicted in  FIG. 2 , omitted from  FIGS. 5A-5C  for illustrative purposes). The force sensors may be arranged in various manners to facilitate detection of various inputs, such as depicted above with respect to  FIGS. 4A-4D . 
     For example,  FIG. 5A  depicts a watch crown  502  having two force sensors. A first force sensor includes a drive electrode  516   a  and a sense electrode  518 A positioned at the top of the stud  512 . A second force sensor includes a drive electrode  516   b  and a sense electrode  518   b  positioned at the bottom of the stud  512 . 
     In operation, a charge may be placed on the first drive electrode  516   a , and a capacitance across the first drive electrode  516   a  and the first sense electrode  518   a  may be monitored. As a force is applied to the crown cap  510 , the distance between the first drive electrode  516   a  and the first sense electrode  518   a  may change, resulting in the capacitance between the electrodes exhibiting a corresponding change. The change in capacitance may be interpreted by a processing unit as an amount of force (e.g., one or more force values) applied to the crown cap. Each force sensor may operate in a similar manner. 
     As depicted in  FIG. 5A , the drive electrode  516   a ,  516   b  in one or both force sensors may be offset from the corresponding sense electrode  518   a ,  518   b . Because of this offset, the capacitance may change in distinct manners for distinct force inputs. For example, a force downward (along the y-axis) may increase a detected capacitance at the force sensor above the stud  512  (drive electrode  516   a  and sense electrode  518   a ), while decreasing a detected capacitance at the force sensor below the stud  512  (drive electrode  516   a  and sense electrode  518   a ). A force toward the stud  512  along the z-axis decreases the detected capacitance at both force sensors. 
     A force along a particular axis may cause an increase or a decrease in capacitance at each force sensor (represented by pairs of drive electrodes and sense electrodes). The below table illustrates how a force along each direction may cause the measured capacitance of each force sensor to increase (+) or decrease (−). It should be understood that the magnitude of capacitance change may vary between each force sensor even where the two sensors increase or two sensors decrease. 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Force direction 
                 516a, 518a 
                 516b, 518b 
               
               
                   
                   
               
             
            
               
                   
                 X+ 
                 − 
                 − 
               
               
                   
                 X− 
                 − 
                 − 
               
               
                   
                 Y+ 
                 − 
                 + 
               
               
                   
                 Y− 
                 + 
                 − 
               
               
                   
                 Z+ 
                 + 
                 + 
               
               
                   
                 Z− 
                 − 
                 − 
               
               
                   
                   
               
            
           
         
       
     
     The table above illustrates the X+, X−, and Z− directions as all having similar responses in the force sensors. Accordingly, in many embodiments at least one additional force sensor (not depicted in the cross-section of  FIG. 5A ) may be configured to distinguish force along the x-axis. For example, a force sensor may be positioned behind the stud  512  which detects an increased capacitance in response to force along the X+ direction and a decreased capacitance in response to force along the X− direction. Another force sensor may be positioned in front of the stud  512  which has the reverse response to forces along the x-axis. 
     In other embodiments, the watch crown  502  may include additional force sensors, or the force sensors may be arranged differently. For example, as depicted in  FIG. 5B , a first force sensor may be formed from a first drive electrode  516   c  and a first sense electrode  518   c  positioned at the top of the stud  512 . Another force sensor may be formed from a second drive electrode  516   d  and a second sense electrode  518   d  positioned at the protruding end of the stud  512 . Similar to the arrangement of  FIG. 5A , the force sensors depicted in  FIG. 5B  may be positioned to distinguish between force inputs along different directions, in which capacitance may increase as the electrodes in a force sensor move together or the overlapping plate area increases, and capacitance may decrease as the electrodes in a force sensor move apart or the overlapping plate area decreases. 
     The below table illustrates how a force along each direction may cause the measured capacitance of each force sensor to increase (+) or decrease (−). 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Force direction 
                 516c, 518c 
                 516d, 518d 
               
               
                   
                   
               
             
            
               
                   
                 X+ 
                 − 
                 − 
               
               
                   
                 X− 
                 − 
                 − 
               
               
                   
                 Y+ 
                 − 
                 − 
               
               
                   
                 Y− 
                 + 
                 − 
               
               
                   
                 Z+ 
                 − 
                 − 
               
               
                   
                 Z− 
                 − 
                 + 
               
               
                   
                   
               
            
           
         
       
     
     The table above illustrates the X+, X−, and Z− directions as all having similar responses in the force sensors. Accordingly, in many embodiments at least one additional force sensor (not depicted in the cross-section of  FIG. 5B ) may be configured to distinguish force along the x-axis. For example, a force sensor may be positioned behind the stud  512  which detects an increased capacitance in response to force along the X+ direction and a decreased capacitance in response to force along the X− direction. Another force sensor may be positioned in front of the stud  512  which has the reverse response to forces along the x-axis. 
     As depicted in  FIG. 5C , additional force sensors may be included in a watch crown  502  to provide additional data points available to register and interpret a force input to the watch crown  502 . For example, force sensors may be formed between a first drive electrode  516   e  and a first sense electrode  518   e ; between a second drive electrode  516   f  and a second sense electrode  518   f ; between a third drive electrode  516   g  and a third sense electrode  518   g ; between a fourth drive electrode  516   h  and a fourth sense electrode  518   h ; and between a fifth drive electrode  516   j  and a fifth sense electrode  518   j.    
     The below table illustrates how a force along each direction may cause the measured capacitance of each force sensor to increase (+) or decrease (−). 
     
       
         
           
               
               
               
               
               
               
             
               
                   
               
               
                 Force 
                   
                   
                   
                   
                   
               
               
                 direction 
                 516e, 518e 
                 5161, 518b1 
                 516g, 518g 
                 516h, 518h 
                 516j, 518j 
               
               
                   
               
             
            
               
                 X+ 
                 − 
                 − 
                 − 
                 − 
                 − 
               
               
                 X− 
                 − 
                 − 
                 − 
                 − 
                 − 
               
               
                 Y+ 
                 − 
                 − 
                 − 
                 − 
                 + 
               
               
                 Y− 
                 + 
                 − 
                 − 
                 − 
                 − 
               
               
                 Z+ 
                 − 
                 − 
                 − 
                 − 
                 − 
               
               
                 Z− 
                 − 
                 + 
                 + 
                 + 
                 − 
               
               
                   
               
            
           
         
       
     
     The table above illustrates the X+, X−, and Z− directions as all having similar responses in the force sensors. Accordingly, in many embodiments at least one additional force sensor (not depicted in the cross-section of  FIG. 5C ) may be configured to distinguish force along the x-axis. For example, a force sensor may be positioned behind the stud  512  which detects an increased capacitance in response to force along the X+ direction and a decreased capacitance in response to force along the X− direction. Another force sensor may be positioned in front of the stud  512  which has the reverse response to forces along the x-axis. 
     The multiple force sensors depicted in  FIG. 5C  along the end of the stud  512  (e.g., formed by drive electrodes  516   f ,  516   g ,  516   h  and sense electrodes  518   f ,  518   g ,  518   h ) may further facilitate distinguishing forces at oblique angles, such as forces causing a tilt as depicted in  FIG. 4D . In some embodiments, additional force sensors may be included around the stud  512  to distinguish force inputs along additional directions and further clarify the direction of force being detected. 
     In many embodiments, a processing unit correlates an amount of force exerted on the crown cap  510  with changes in capacitance at one or more force sensors. The changes in capacitance may thus be expressed with a given magnitude and signed value. Generally, a positive value indicates an increase in capacitance, and a negative value indicates a decrease in capacitance. The processing unit may compare the magnitude and sign of changes at each pixel, along with a known location of each pixel, in order to determine a vector representing the magnitude and three-dimensional direction of an input to the watch crown  502 . The accuracy of the determined vector may depend on the location and number of force sensors, with an increased number of force sensors generally yielding a more accurate determination. 
     In some embodiments, the capacitance measurements of the force sensors may be processed in other ways in order to determine an input to the watch crown  502  based on the measurements. For example, the processing unit may be coupled to a memory storing input profiles, in which the measured changes in capacitance may be compared to the input profiles to determine a type of user input. 
       FIGS. 2-5C  have been discussed generally with reference to detecting a force applied to the watch crown using capacitive force sensing elements. It should be understood that embodiments of the present disclosure may incorporate other force or displacement sensing elements to achieve similar aims. For example, each force sensor may be formed using a strain gauge, a piezoelectric sensor, a force-sensitive resistor, and similar force or displacement sensing elements. Accordingly, discussion of force sensors with reference to capacitive force sensing are illustrative in nature and would apply similarly to other force or displacement sensing elements. 
       FIG. 6  depicts a cross-section of another example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . The watch crown  602  includes a shaft  640  which rotatably couples to the housing  608  of the electronic device. The shaft  640  extends outward from the housing  608  and couples to a crown cap  610 . In some embodiments, the shaft  640  and/or crown cap  610  are formed from a rigid material, such as metal (e.g., aluminum, steel, copper, brass, etc.), plastic, glass, acrylic, ceramic, other materials, or combinations of materials. In some embodiments, the shaft  640  and crown cap  610  are integrally formed, while in other embodiments they may be separately formed and coupled together. 
     The crown cap  610  may provide an input surface for user interaction. For example, the watch crown  602  may facilitate displacement to the watch crown  602  along three axes: the x-axis (lateral in a first direction relative to the shaft  640 ), the y-axis (lateral in a second direction relative to the shaft  640 ), and the z-axis (axially, or along the axis of the shaft  640 ). For example, a series of force sensors  654   a ,  654   b ,  654   c  may be placed on or around an internal portion of the shaft  640 . The force sensors  654   a ,  654   b ,  654   c  may detect an amount and direction of force applied to the crown cap  610 , as translated to the end of the shaft  640 . For example, the force sensors  654   a ,  654   b ,  654   c  may deform in response to movements of the shaft  640  in a manner similar to the force sensors depicted in  FIGS. 4A-5C . 
     Generally, the crown cap  602  and the shaft  640  may also receive rotational inputs. For example, the shaft  640  may be a rotatable shaft and rotational input to the watch crown  602  may be detected by positional sensors  650   a ,  650   b . In some embodiments, positional sensors  650   a ,  650   b  may be coupled to the housing  608  adjacent the crown cap  610 . The positional sensors  650   a ,  650   b  may detect the rotational position of the crown cap by detecting the location of one or more electrodes  652   a ,  652   b  or other positional indicators on the crown cap  610 . The positional sensors  650   a ,  650   b  may operate by capacitive sensing, optical sensing, strain sensing, or similar techniques. A number of positional sensors  650   a ,  650   b  and/or electrodes (positional indicators)  652   a ,  652   b  may be included in the watch crown  602  to enable detection of the rotational position of the crown cap  610 , and may additionally enable a determination of the speed, acceleration, and similar attributes of rotational inputs. 
     A processing unit coupled to the positional sensors  650   a ,  650   b  may determine an amount of movement, speed, acceleration, and/or other attributes of rotational inputs. In some embodiments, the processing unit may determine whether an amount of rotation exceeds a threshold, and may register an input (e.g., scrolling through a list of items, or otherwise changing an indicium on the display) once the amount of rotation exceeds the threshold. 
     In many embodiments, the shaft  640  is coupled to the housing  608  by a retaining clip  622 , or similar fastener, which may retain the end of the shaft  640  within the housing  608 , while allowing the shaft  640  to rotate about the z-axis, and be displaced slightly along the x-, y-, and z-axes. In some embodiments, a compliant material (omitted from  FIG. 6  for clarity) may surround all or a portion of the shaft. The compliant material may facilitate a transfer of force from the shaft  640  to the force sensors  654   a ,  654   b ,  654   c . The watch crown may include additional elements, such as an O-ring  624 , which may be similar to elements depicted in  FIG. 2 . 
       FIG. 7  depicts a cross-section of another example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . The watch crown  702  may be similar to the watch crown  202  depicted in  FIG. 2 . Here, the crown cap  710  may couple to a protrusion  742  from the housing  708  of the electronic device. In some embodiments, the protrusion  742  is formed integrally with the housing  708 , while in other embodiments the protrusion  742  is formed separately and coupled to the housing  708 . 
     Similar to the watch crown  202  of  FIG. 2 , a compliant material  746  may be placed between the crown cap  710  and the protrusion  742  to facilitate displacement of the crown cap  710  along the x-, y-, and z-axes, and may also facilitate partial rotation of the crown cap  710 . The watch crown  702  may also include a gasket  744  (such as a silicone or a rubber gasket) coupled to the crown cap  710  and/or the housing  708  at the edge of the crown cap  710  to prevent entry of contaminants. 
     The watch crown  702  may further include force sensors, such as a series of capacitive force sensors (similar to the force sensors described with respect to  FIGS. 4A-5C ) formed using drive electrodes  716   a ,  716   b ,  716   c  coupled to the crown cap  710  and corresponding sense electrodes  718   a ,  718   b ,  718   c  coupled to the protrusion  742 . As force is applied to the crown cap  710 , the compliant material  746  between the first drive electrode  716   a  and the first sense electrode  718   a  may be compressed, resulting in a change in capacitance across the first drive electrode  716   a  and the first sense electrode  718   a.    
       FIG. 8  depicts a cross-section of another example embodiment of a watch crown coupled to the housing of the electronic device of  FIG. 1 , taken along line A-A of  FIG. 1 . The watch crown  702  may be similar to the watch crown  202  depicted in  FIG. 2 , the watch crown  602  depicted in  FIG. 6 , and/or the watch crown  702  depicted in  FIG. 7 . The watch crown  802  includes a shaft  840  which rotatably couples to the housing  808  of the electronic device. The shaft  840  extends outward from the housing  808  into a flared end  848  and couples to a crown cap  810 . The watch crown  802  may also include an O-ring  824  housed within a depression of the housing  808  and/or the shaft  840 . 
     A compliant material  846  may be placed between the crown cap  810  and the flared end  848  of the shaft  840  to facilitate displacement of the crown cap  810  along the x-, y-, and z-axes. A series of capacitive force sensors may be formed using drive electrodes  816   a ,  816   b ,  816   c  coupled to the crown cap  810  and corresponding sense electrodes  818   a ,  818   b ,  818   c  coupled to the flared end  848  of the shaft  840 . 
     The watch crown  802  may further receive rotational inputs to the crown cap  810 , causing the shaft  840  to rotate about the z-axis. One or more positional sensors  850  may be coupled to the housing  808  adjacent the crown cap  810 . The positional sensor  850  may detect a rotational position of the crown cap  810  by detecting the location of one or more electrodes  852  or other positional indicators on the crown cap  810 . 
       FIGS. 9A-11B  generally depict examples of manipulating graphics displayed on an electronic device through inputs provided by force and/or rotational inputs to a crown of the device. This manipulation (e.g., selection, acknowledgement, motion, dismissal, magnification, and so on) of a graphic may result in changes in operation of the electronic device and/or graphics displayed by the electronic device. Although specific examples are provided and discussed, many operations may be performed by rotating and/or applying force to a crown such as the examples described above. Accordingly, the following discussion is by way of example and not limitation. 
       FIG. 9A  depicts an example electronic device  900  (shown here as an electronic watch) having a watch crown  902 . The watch crown  902  may be similar to the examples described above, and may receive force inputs along a first lateral direction, a second lateral direction, or an axial direction of the watch crown. The watch crown  902  may also receive rotational inputs. A display  906  shows information and/or other graphics. In the current example, the display  906  depicts a list of various items  961 ,  962 ,  963 , all of which are example indicia. 
       FIG. 9B  illustrates how the graphics shown on the display  906  change as the watch crown  902  rotates, partially or completely (as indicated by the arrow  960 ). Rotating the watch crown  902  causes the list to scroll or otherwise move on the screen, such that the first item  961  is no longer displayed, the second and third items  962 ,  963  each move upwards on the display, and a fourth item  964  is now shown at the bottom of the display. This is one example of a scrolling operation that can be executed by rotating the watch crown  902 . Such scrolling operations may provide a simple and efficient way to depict multiple items relatively quickly and in sequential order. A speed of the scrolling operation may be controlled by the amount of rotational force applied to the watch crown  902  and/or the speed at which the watch crown  902  is rotated. Faster or more forceful rotation may yield faster scrolling, while slower or less forceful rotation yields slower scrolling. The watch crown  902  may receive an axial force (e.g., a force inward toward the display  906  or watch body) to select an item from the list, in certain embodiments. 
       FIGS. 10A and 10B  illustrate an example zoom operation. The display  1006  depicts a picture  1066  at a first magnification, shown in  FIG. 10A ; the picture  1066  is yet another example of an indicium. A user may apply a lateral force (e.g., a force along the x-axis) to the watch crown  1002  of the electronic device  1000  (illustrated by arrow  1065 ), and in response the display may zoom into the picture  1066 , such that a portion  1067  of the picture is shown at an increased magnification. This is shown in  FIG. 10B . The direction of zoom (in vs. out) and speed of zoom, or location of zoom, may be controlled through force applied to the watch crown  1002 , and particularly through the direction of applied force and/or magnitude of applied force. Applying force to the watch crown  1002  in a first direction may zoom in, while applying force to the watch crown  1002  in an opposite direction may zoom out. Alternately, rotating or applying force to the watch crown  1002  in a first direction may change the portion of the picture subject to the zoom effect. In some embodiments, applying an axial force (e.g., a force along the z-axis) to the watch crown  1002  may toggle between different zoom modes or inputs (e.g., direction of zoom vs. portion of picture subject to zoom). In yet other embodiments, applying force to the watch crown  1002  along another direction, such as along the y-axis, may return the picture  1066  to the default magnification shown in  FIG. 10A . 
       FIGS. 11A and 11B  illustrate possible use of the watch crown  1102  to change an operational state of the electronic device  1100  or otherwise toggle between inputs. Turning first to  FIG. 11A , the display  1106  depicts a question  1168 , namely, “Would you like directions?” As shown in  FIG. 11B , a lateral force may be applied to the watch crown  1102  (illustrated by arrow  1170 ) to answer the question. Applying force to the watch crown  1102  provides an input interpreted by the electronic device  1100  as “yes,” and so “YES” is displayed as a graphic  1169  on the display  1106 . Applying force to the watch crown  1102  in an opposite direction may provide a “no” input. Both the question  1168  and graphic  1169  are examples of indicia. 
     In the embodiment shown in  FIGS. 11A and 11B , the force applied to the watch crown  1102  is used to directly provide the input, rather than select from options in a list (as discussed above with respect to  FIGS. 9A and 9B ). 
     As mentioned previously, force or rotational input to a watch crown of an electronic device may control many functions beyond those listed here. The watch crown may receive distinct force or rotational inputs to adjust a volume of an electronic device, a brightness of a display, or other operational parameters of the device. A force or rotational input applied to the watch crown may rotate to turn a display on or off, or turn the device on or off. A force or rotational input to the crown may launch or terminate an application on the electronic device. Further, combinations of inputs to the watch crown may likewise initiate or control any of the foregoing functions, as well. 
       FIG. 12  depicts example components of an electronic device in accordance with the embodiments described herein. The schematic representation depicted in  FIG. 12  may correspond to components of the devices depicted in  FIGS. 1-11B , described above. However,  FIG. 12  may also more generally represent other types of devices with a tri-axial input mechanism similar to the watch crown described above. 
     As shown in  FIG. 12 , a device  1200  includes a processing unit  1280  operatively connected to computer memory  1286 . The processing unit  1280  may be operatively connected to the memory  1286  via an electronic bus or bridge. The processing unit  1280  may include one or more computer processors or microcontrollers that are configured to perform operations in response to computer-readable instructions. Additionally or alternatively, the processing unit  1280  may include other processors within the device  1200  including application specific integrated chips (ASIC) and other microcontroller devices. The processing unit  1280  may be configured to perform functionality described in the examples above. 
     The memory  1286  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  1286  is configured to store computer-readable instructions, sensor values, and other persistent software elements. 
     In this example, the processing unit  1280  is operable to read computer-readable instructions stored on the memory  1286 . The computer-readable instructions may adapt the processing unit  1280  to perform the operations or functions described above with respect to  FIGS. 1-8 . The computer-readable instructions may be provided as a computer-program product, software application, or the like. 
     For example, the memory  1286  may store a plurality of input profiles, correlating a particular profile of force sensor measurements to a particular input or type of input. Accordingly, when the processing unit  1280  detects a force input to the watch crown or similar input device, the processing unit  1280  may compare the measurements of distinct force sensors to the input profile. If the force measurements match an input profile, the force measurements may be correlated (e.g., associated) with a particular type of input and processed accordingly. 
     The device  1200  may include a display  1282  that is configured to render visual information generated by the processing unit  1280 . The display  1282  may include a liquid-crystal display (LCD), organic light emitting diode (OLED) display, organic electroluminescent (OEL) display, or the like. If the display  1282  is an LCD, the display may also include a backlight component that can be controlled to provide variable levels of display brightness. If the display  1282  is an OLED or OEL type display, the brightness of the display  1282  may be controlled by modifying the electrical signals that are provided to display elements. 
     The device  1200  may also include a power source  1284 , such as a battery, that is configured to provide electrical power to the components of the device  1200 . The power source  1284  may include one or more power storage cells that are linked together to provide an internal supply of electrical power. The power source  1284  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 power source  1284 , via power management circuitry, may be configured to receive power from an external source, such as an AC power outlet. The power source  1284  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/output components  1290 . The input/output component  1290  is a device that is configured to receive user input. The input/output component  1290  may include, for example, a push button, a touch-activated button, or the like. In some embodiments, the input/output components  1290  may provide a dedicated or primary function, including, for example, a power button, volume buttons, home buttons, scroll wheels, and camera buttons. Generally, a force sensor and a positional sensor may also be classified as an input component. However, for purposes of this illustrative example, the force sensors  1288  and the positional sensors  1294  are depicted as distinct components within the device  1200 . 
     The device  1200  may also include one or more positional sensors  1294  configured to determine a rotational position of a watch crown. The positional sensors  1294  may detect the rotational position of the crown cap by detecting the location of one or more electrodes or other positional indicators on the crown cap. The positional sensors  1294  may operate by capacitive sensing, optical sensing, or similar techniques. The positional sensors  1294  are coupled to the processing unit  1280  which may determine the speed, acceleration, and similar attributes of rotational inputs. 
     The device  1200  may also include one or more force sensors  1288  in accordance with the embodiments described herein. As previously described, the force sensors  1288  may be configured to receive force input to the watch crown. In some embodiments, the force sensors  1288  may be implemented in a pair of flexible circuits coupled to an insulating substrate. In some embodiments, other force-sensitive structures may be employed, such as a strain gauge, a piezoelectric sensor, a force sensitive resistor, and similar force sensing elements. 
     The device  1200  may also include a haptic device  1292 . The haptic device  1292  may be implemented with a number of devices and technologies, such as an electromechanical actuator. The haptic device  1292  may be controlled by the processing unit  1280 , and may be configured to provide haptic feedback to a user interacting with the device  1200 . 
     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 intended 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.

Metadata:
Filing Date: 20180124
Publication Date: 20210330
Grant Date: 20210330
Priority Date: 20170718
Inventors: ELY, COLIN M.
DE JONG, ERIK G.
CARDINALI, STEVEN P.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/0362", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0482", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1684", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G21/02", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04G17/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G21/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04G9/0005", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G21/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04G9/0005", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 75164464