PATENT DOCUMENT

Publication Number: US-10474108-B2
Application Number: US-201715717782-A
Country: US
Kind Code: B2

Title: Magnetic sensor array for crown rotation

Abstract:
An electronic device is disclosed. In some examples, a crown comprising a housing can be operatively coupled to a body of the electronic device, and configured to rotate in a first direction with respect to the body of the electronic device in response to a mechanical input provided by the user. A rotating member can be disposed at least partially inside the crown housing and configured to rotate in the first direction in response to the mechanical input. A first magnetic sensing cell can be attached to the rotating member at a first location of the rotating member and can be electrically connected to an electronic circuit. A magnet can be configured to remain stationary with respect to the body of the electronic device. The electronic circuit can be configured to generate a first signal corresponding to a rotational position of the crown with respect to the body of the electronic device.

Claims:
What is claimed is: 
     
       1. An electronic device configured to be worn by a user comprising:
 a crown operatively coupled to a body of the electronic device and configured to rotate in a first direction with respect to the body of the electronic device in response to a mechanical input provided by the user, the crown comprising a housing; 
 a rotating member comprising a flexible substrate disposed at least partially inside the housing and configured to rotate in the first direction in response to the mechanical input; 
 a first magnetic sensing cell attached to the rotating member at a first location of the flexible substrate and electrically connected to a first electronic circuit; and 
 a magnet configured to remain stationary with respect to the body of the electronic device; 
 
       wherein the first electronic circuit is configured to generate a first signal corresponding to a rotational position of the crown with respect to the body of the electronic device. 
     
     
       2. The electronic device of  claim 1 , wherein the first magnetic sensing cell is configured to provide to the first electronic circuit a signal corresponding to a strength, at a position of the first magnetic sensing cell, of a magnetic field corresponding to the magnet. 
     
     
       3. The electronic device of  claim 1 , wherein the first electronic circuit is attached to the rotating member and configured to rotate in the first direction in response to the mechanical input. 
     
     
       4. The electronic device of  claim 1 , wherein the magnet is disposed at least partially inside the body of the electronic device. 
     
     
       5. The electronic device of  claim 1 , wherein the magnet is disposed at least partially inside the housing. 
     
     
       6. The electronic device of  claim 5 , wherein:
 the housing comprises a circular groove, 
 the magnet is disposed partially inside the circular groove, and 
 the housing is configured to rotate around the magnet. 
 
     
     
       7. The electronic device of  claim 1 , further comprising a second magnetic sensing cell attached to the rotating member at a second location of the rotating member and electrically coupled to a switching mechanism, wherein:
 the switching mechanism is configured to selectively couple one of the first magnetic sensing cell and the second magnetic sensing cell to the first electronic circuit. 
 
     
     
       8. The electronic device of  claim 7 , wherein the electronic device further comprises a processor configured to:
 determine a first magnetic field strength based on a signal from the first magnetic sensing cell; 
 determine a second magnetic field strength based on a signal from the second magnetic sensing cell; and 
 in accordance with a determination that the first magnetic field strength is greater than the second magnetic field strength, determine the rotational position of the crown with respect to the body of the electronic device. 
 
     
     
       9. The electronic device of  claim 8 , wherein the processor is attached to the rotating member. 
     
     
       10. A method of generating a signal corresponding to a rotational position of a crown operatively coupled to a body of an electronic device configured to be worn by a user, the crown comprising a housing, the method comprising:
 receiving, at an electronic circuit from a first magnetic sensing cell, a first signal corresponding to a position of the first magnetic sensing cell with respect to a magnet configured to remain stationary with respect to the body of the electronic device, wherein:
 the first magnetic sensing cell is attached to a rotating member comprising a flexible substrate disposed at least partially inside the housing, 
 the crown is configured to rotate in a first direction in response to a mechanical input provided by the user, and 
 the rotating member is configured to rotate in the first direction in response to the mechanical input; and 
 
 generating, at the electronic circuit based on the first signal, a second signal corresponding to a rotational position of the crown with respect to the body of the electronic device. 
 
     
     
       11. The method of  claim 10 , wherein the first signal corresponds to a strength, at a position of the first magnetic sensing cell, of a magnetic field corresponding to the magnet. 
     
     
       12. The method of  claim 10 , wherein the electronic circuit is attached to the rotating member and configured to rotate in the first direction in response to the mechanical input. 
     
     
       13. The method of  claim 10 , wherein the magnet is disposed at least partially inside the body of the electronic device. 
     
     
       14. The method of  claim 10 , wherein the magnet is disposed at least partially inside the housing. 
     
     
       15. The method of  claim 14 , wherein:
 the housing comprises a circular groove, 
 the magnet is disposed partially inside the circular groove, and 
 the housing is configured to rotate around the magnet. 
 
     
     
       16. The method of  claim 10 , wherein:
 a second magnetic sensing cell is attached to the rotating member at a second location of the rotating member and electrically coupled to a switching mechanism, and 
 the switching mechanism is configured to selectively couple one of the first magnetic sensing cell and the second magnetic sensing cell to the first electronic circuit. 
 
     
     
       17. The method of  claim 16 , further comprising:
 determining a first magnetic field strength based on a signal from the first magnetic sensing cell; 
 determining a second magnetic field strength based on a signal from the second magnetic sensing cell; and 
 in accordance with a determination that the first magnetic field strength is greater than the second magnetic field strength, determining the rotational position of the crown with respect to the body of the electronic device. 
 
     
     
       18. The method of  claim 17 , wherein the electronic circuit comprises a processor attached to the rotating member. 
     
     
       19. An electronic device configured to be worn by a user comprising:
 means for rotating a crown in a first direction with respect to a body of the electronic device in response to a mechanical input provided by the user; 
 first magnetic sensing means for detecting a first strength of a magnetic field corresponding to a magnet; 
 second magnetic sensing means for detecting a second strength of the magnetic field corresponding to the magnet; 
 means for selectively coupling one of the first magnetic sensing means and the second magnetic sensing means to an electronic circuit; and 
 means for determining, based on an output of the first magnetic sensing means and an output of the second magnetic sensing means, a rotational position of the crown with respect to the body of the electronic device, 
 
       wherein:
 the first magnetic sensing means and the second magnetic sensing means are disposed on a flexible substrate and are configured to rotate in the first direction in response to the mechanical input provided by the user, and 
 the magnet is configured to remain stationary with respect to the body of the electronic device.

Description:
FIELD OF THE DISCLOSURE 
     This relates generally to user inputs, such as rotational inputs, and more particularly, to using magnetic sensing to detect a rotational input. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch and the position of the touch on the touch sensor panel, and the computing system can then interpret the touch in accordance with the display appearing at the time of the touch, and thereafter can perform one or more actions based on the touch. In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing electrical fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface. 
     In addition to touch panels/touch screens, many electronic devices may also have mechanical inputs (or mechanical input mechanisms), such as buttons, switches, and/or knobs. These mechanical inputs can control power (i.e., on/off) and volume for the electronic devices, among other functions. However, interfacing mechanical inputs, particularly rotational mechanical inputs, to an electronic device may require electronic instrumentation which may be difficult to integrate into the electronic device, for example because the instrumentation may be undesirably large, may require high power consumption, or may require complex processing, or may be subject to environmental interference. Further, conventional technologies for providing rotational mechanical input can exhibit limited dynamic range and non-linear response, both of which can complicate integration of the mechanical input into larger systems. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to magnetic sensors for enabling inputs for manipulating a user interface on a wearable electronic device using a mechanical rotary input (e.g., a crown). In some examples, a crown comprising a housing can be operatively coupled to a body of the electronic device, and configured to rotate in a first direction with respect to the body of the electronic device in response to a mechanical input provided by the user. A rotating member can be disposed at least partially inside the crown housing and configured to rotate in the first direction in response to the mechanical input. A first magnetic sensing cell can be attached to the rotating member at a first location of the rotating member and can be electrically connected to an electronic circuit. A magnet can be configured to remain stationary with respect to the body of the electronic device. The electronic circuit can be configured to generate a first signal corresponding to a rotational position of the crown with respect to the body of the electronic device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary personal device in which the rotational input sensing of the disclosure can be implemented according to examples of the disclosure. 
         FIG. 2  illustrates an exemplary block diagram of components within an exemplary device according to examples of the disclosure. 
         FIG. 3  illustrates an exemplary finger interacting with a protruding rotary input according to examples of the disclosure. 
         FIGS. 4A-4C  illustrate an exemplary configuration for detecting rotational movement of a crown via magnetic sensing according to examples of the disclosure. 
         FIG. 5  illustrates an exemplary electronic circuit in an exemplary magnetic sensing cell according to examples of the disclosure. 
         FIG. 6  illustrates an exemplary electronic circuit for generating a digital signal corresponding to the output of a magnetic sensing cell according to examples of the disclosure. 
         FIGS. 7A-7B  illustrate an example of computing a rotational position of a crown using a magnetic sensing cell according to examples of the disclosure. 
         FIGS. 8A and 8B  illustrate examples of calculating a rotational position of a crown from an output signal of a magnetic sensing cell according to examples of the disclosure. 
         FIG. 9  illustrates an example of determining a rotational position of a crown using a plurality of magnetic sensor cells according to examples of the disclosure. 
         FIG. 10  illustrates an example computing system for implementing rotational input sensing according to examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be practiced and structural changes can be made without departing from the scope of the disclosure. 
       FIG. 1  illustrates exemplary personal electronic device  100  in which the sensing of the disclosure can be implemented according to examples of the disclosure. In the illustrated example, device  100  can be a watch that generally includes body  102  and strap  104  for affixing device  100  to the body of a user. That is, device  100  can be wearable. Body  102  can be designed to couple to straps  104 . Device  100  can have touch-sensitive display screen  106  (hereafter touchscreen) and crown  108 . Device  100  can also have buttons  110 ,  112 , and  114 . Though device  100  is illustrated as being a watch, it is understood that the examples of the disclosure can be implemented in devices other than watches, such as tablet computers, mobile phones, or any other wearable or non-wearable electronic device that can include a rotary input such as a crown. Device  100  may be viewed as a host device with respect to crown  108 . 
     Conventionally, the term ‘crown,’ in the context of a watch, can refer to the cap atop a stem or shaft for winding the watch. In the context of a personal electronic device  100 , the crown can be a physical component of the electronic device, rather than a virtual crown on a touch sensitive display. Crown  108  can be mechanical, meaning that it can be connected to a sensor for converting physical movement of the crown into electrical signals. Crown  108  can rotate in two directions of rotation (e.g., forward and backward, or clockwise and counter-clockwise). Crown  108  can also be pushed in toward the body  102  of device  100  and/or be pulled away from the device. Crown  108  can be touch-sensitive, for example, using capacitive touch technologies or other suitable technologies that can detect whether a user is touching the crown. Moreover, in some examples, crown  108  can further be configured to tilt in one or more directions or slide along a track at least partially around a perimeter of body  102 . In some examples, more than one crown  108  can be included in device  100 . The visual appearance of crown  108  can, but need not, resemble crowns of conventional watches. Buttons  110 ,  112 , and  114 , if included, can each be a physical or a touch-sensitive button. That is, the buttons may be, for example, physical buttons or capacitive buttons. Further, body  102 , which can include a bezel, may have predetermined regions on the bezel that act as buttons. 
     Display  106  can include a display device, such as a liquid crystal display (LCD), light-emitting diode (LED) display, organic light-emitting diode (OLED) display, or the like, positioned partially or fully behind or in front of a touch sensor panel implemented using any desired touch sensing technology, such as mutual-capacitance touch sensing, self-capacitance touch sensing, resistive touch sensing, projection scan touch sensing, or the like. Display  106  can allow a user to perform various functions by touching or hovering near the touch sensor panel using one or more fingers or other objects. 
       FIG. 2  illustrates an exemplary block diagram of components within an exemplary device  200  according to examples of the disclosure. In some examples, crown  208  (which can correspond to crown  108  described above) can be coupled to encoder  204 , which can be configured to monitor a physical state or change of physical state of the crown (e.g., the position and/or rotational state of the crown), convert it to an electrical signal (e.g., convert it to an analog or digital signal representation of the position or change in position of the crown), and provide the signal to processor  202  (which may be viewed as a host processor). In some examples, crown  208  (which can correspond to crown  108  described above) can be coupled to encoder  204 , which can be configured to monitor a physical state or change of physical state of the crown (e.g., the position and/or rotational state of the crown), convert it to an electrical signal (e.g., convert it to an analog or digital signal representation of the position or change in position of the crown), and provide the signal to processor  202 . For instance, in some examples, encoder  204  can be configured to sense the absolute rotational position (e.g., an angle between 0-360°) of crown  208  and output an analog or digital representation of this position to processor  202 . Alternatively, in other examples, encoder  204  can be configured to sense a change in rotational position (e.g., a change in rotational angle) of crown  208  over some sampling period and to output an analog or digital representation of the sensed change to processor  202 . In these examples, the crown position information can further indicate a direction of rotation of the crown  208  (e.g., a positive value can correspond to one direction and a negative value can correspond to the other). In yet other examples, encoder  204  can be configured to detect a rotation of crown  208  in any desired manner (e.g., velocity, acceleration, or the like) and can provide the crown rotational information to processor  202 . The rotational velocity can be expressed in numerous ways. For example, the rotational velocity can be expressed as a direction and a speed of rotation, such as hertz, as rotations per unit of time, as rotations per frame, as revolutions per unit of time, as revolutions per frame, as a change in angle per unit of time, and the like. In alternative examples, instead of providing information to processor  202 , this information can be provided to other components of device  200 , such as, for example, a state machine. 
     In some examples, the state of the display  206  (which can correspond to display  106  described above) can control physical attributes of crown  208 . For example, if display  206  shows a cursor at the end of a scrollable list, crown  208  can have limited motion (e.g., cannot be rotated forward). In other words, the physical attributes of the crown  208  can be conformed to a state of a user interface that is displayed on display  206 . In some examples, a temporal attribute of the physical state of crown  208  can be used as an input to device  200 . For example, a fast change in physical state can be interpreted differently than a slow change in physical state. These temporal attributes can also be used as inputs to control physical attributes of the crown. 
     Processor  202  can be further coupled to receive input signals from buttons  210 ,  212 , and  214  (which can correspond to buttons  110 ,  112 , and  114 , respectively), along with touch signals from touch-sensitive display  206 . Processor  202  can be configured to interpret these input signals and output appropriate display signals to cause an image to be produced by touch-sensitive display  206 . While a single processor  202  is shown, it should be appreciated that any number of processors or other computational devices can be used to perform the functions described above. 
       FIG. 3  illustrates an exemplary finger  314  interacting with a protruding rotary input  308  according to examples of the disclosure.  FIG. 3  depicts an exemplary rotary input  308  (which can correspond to crown  108  and/or a rotating bezel above) that can rotate in rotational direction  322  as well as be displaced in direction  324 , i.e. translated along the direction of the rotation axis toward and/or away from a device (e.g., device  100  above), according to examples of the disclosure. Finger  314  can be resting on rotary input  308 , and can be providing rotational input to the rotary input in rotational direction  322 . 
     Examples of the disclosure are directed to configurations of an encoder, such as encoder  204  described above with respect to  FIG. 2 , that utilize magnetic sensing to detect rotation of a crown, such as crown  208 . Compared with conventional encoder technologies, such as optical sensing, magnetic sensing can offer reduced power usage; high dynamic range; linear response; resistance to environmental noise; and a compact physical footprint. These advantages may be particularly desirable for crowns that integrate with wearable devices, such as device  100  above, which must offer reliable operation in a variety of unpredictable physical environments, and typically are powered by batteries of limited capacity. In addition, magnetic sensing technologies may be particularly well-suited to identify an absolute position (rather than a relative position) of a crown. The ability to identify an absolute position may be especially useful for situations in which no reference position (from which to calculate a relative position) is available, or in which a reference position may drift over time; wearable devices, which may be frequently cycled on and off, may frequently present such situations. 
       FIGS. 4A-4C  illustrate an exemplary configuration for detecting rotational movement of a crown via magnetic sensing according to examples of the disclosure.  FIG. 4A  depicts a perspective view of a crown  402  (which can correspond to crown  108  above) coupled to an enclosure of a personal electronic device  400  (which can correspond to device  100  above) via shaft  410 . Device  400  may include or interface to a processor, such as processor  202  described above with respect to  FIG. 1 , which can input and output electronic signals.  FIG. 4B  depicts a front view of the crown, and  FIG. 4C  depicts a cutaway side view of the crown. In the example shown, crown  402  comprises a ring-shaped (or cylindrical) housing  414  comprising a hollow cavity  415  and an outer ring  408  (which can correspond to protruding rotary input  308  above), through which a user interacts with housing  414 . Housing  414  may rotate in rotational direction  418  (relative to device  400 ) in response to rotational input provided to outer ring  408  by a user&#39;s finger (e.g., finger  314  described above with respect to  FIG. 3 ). In some examples, such as shown in  FIGS. 4A and 4B , outer ring  408  may feature a grooved or textured surface to facilitate such input. In some examples, housing  414  may be mechanically coupled to shaft  410 , such that shaft  410  rotates in rotational direction  418  as housing  414  rotates in rotational direction  418 . In the example shown, shaft  410  is concentric with crown  402 . In some examples, housing  414  may be configured to provide electromagnetic shielding to components in the hollow cavity  415 . For example, housing  414  may be constructed of conductive or magnetic material, or may be coated with such material. 
     In the example shown in  FIGS. 4A-4C , crown  402  further includes a circular member  420 , disposed in the hollow cavity  415  of housing  414  and concentric with crown  402  and shaft  410 , that rotates in rotational direction  418  as housing  414  rotates in rotational direction  418 . In some examples, circular member  420  may be a flexible circuit board (i.e., a flexible structure that can carry electronic signals via conductive traces) disposed in a circular shape. In the example shown, one or more magnetic sensing cells  422  are mounted on circular member  420 , such that magnetic sensing cells  422  rotate with circular member  420  as circular member  420  rotates. In the example shown in  FIGS. 4A-4C , magnetic sensing cells  422  include eight individual magnetic sensing cells  422 A- 422 H. However, the disclosure is not limited to any particular number of magnetic sensing cells. Some examples, for instance, may feature  128  such cells, or  256  such cells. As described in more detail below, each of magnetic sensing cells  422  may comprise a magnetically sensitive element, such as a magnetoresistor that exhibits an electrical resistance that varies in relation to a magnetic field. In examples in which housing  414  is configured to provide electromagnetic shielding, such shielding can improve the performance of magnetic sensing cells  422  by reducing stray electromagnetic interference. In some examples, such as in  FIGS. 4A-4C , magnetic sensing cells  422  may be evenly spaced around the circumference of circular member  420 . 
     In the example shown in  FIGS. 4A-4C , an integrated circuit  428  may be mounted to circular member  420  and electronically coupled to one or more of magnetic sensing cells  422 . Integrated circuit  428  may include any components, or exhibit any functionality, that may be associated with an integrated circuit. For example, integrated circuit  428  may include a processor (not shown); may accept input signals and present output signals; may include or interface to a memory (not shown); and may electronically interface with magnetic sensing cells  422  via conductive traces on circular member  420  (e.g., in examples in which circular member  420  is a flexible circuit board). By mounting integrated circuit  428  to circular member  420 , and processing signals from magnetic sensing cells  422  (which may also be mounted to circular member  420 ) directly in integrated circuit  428 , rather than on host processor  202 , the challenge of electronically coupling magnetic sensing cells  422  to a processor may be simplified. For example, as circular member  420  rotates, as described below, magnetic sensing cells  422  may rotate with respect to host device  400 , which may tangle or strain physical connections (e.g., wires) that may exist between the cells and the host device, and which may degrade direct electrical connections that may exist between the cells and the host device (e.g., via friction caused by the rotating member). These problems can be reduced or eliminated by mounting both the processor (e.g., in integrated circuit  428 ) and the magnetic sensing cells  422  to the same rotating member, such that the processor and the cells are fixed relative to one another. 
     In some examples, one or more of magnetic sensing cells  422  and integrated circuit  428  may be configured to electronically couple to host processor  202  of device  400  via head  411  of shaft  410 , for example via conductive leads  424 . Further, in some examples, shaft  410  may electronically connect to device  400  via a B2B (board-to-board) connector (not shown), and may communicate via any of a number of interface protocols (e.g., I2C, SPI). In some examples, wireless communications (e.g., Bluetooth) may be used to connect one or more of magnetic sensing cells  422  and integrated circuit  428  to host processor  202 . In some examples, one or more of magnetic sensing cells  422  and integrated circuit  428  may be configured to receive a supply voltage from host device  400  via a bus, such as a bus disposed inside shaft  410 . 
     The example shown in  FIGS. 4A-4C  includes a magnet  416 , which remains stationary relative to device  400  in response to rotational input applied to housing  414 . That is, while housing  414  and circular member  420  rotate in rotational direction  418 , magnet  416  does not rotate. In some examples, magnet  416  may be mounted to device  400 , and disposed at least partially in the hollow cavity  415  of housing  414 , such that magnet  416  does not rotate with outer ring  408  and circular member  420 . In some examples, magnet  416  may be configured to extend into the cavity  415  via a groove  413  (e.g., a circular groove) in housing  414 , such that housing  414  may rotate freely around magnet  416  while magnet  416  remains stationary with respect to device  400 . In some examples, magnet  416  may be mounted to a plate inside cavity  415 , to a collar of shaft  410  or head  411 , or to another structure wholly or partially inside cavity  415  and configured to remain stationary with respect to device  400  while housing  414  rotates, even though magnet  416  may not be directly mounted to device  400 . Magnet  416  may be any device exhibiting a magnetic field, such as magnetic field  417  shown in  FIG. 4B  (not shown in  FIG. 4A  and  FIG. 4C ). In the example shown, magnet  416  may be a permanent magnet exhibiting a fixed magnetic field. In other examples, magnet  416  may be an electromagnet exhibiting a magnetic field that varies with the current flowing through magnet  416 . In such examples, magnet  416  may be configured to receive a supply voltage from host device  400  via a bus, such as a bus disposed inside shaft  410 . Further, in some examples, magnet  416  may comprise two or more physically separate magnets; the examples of the disclosure are not limited to any particular type or number of such magnets. 
     In some examples, magnet  416  may be disposed wholly or partially inside host device  400 , rather than in the cavity  415  of the housing  414 . Such examples may be mechanically simpler than the example configuration shown in  FIGS. 4A-4C , for example because the magnet may not need to remain stationary inside of a rotating housing. In some examples in which magnet  416  is disposed inside host device  400 , electromagnetic shielding may be provided by a conductive or magnetic material mounted to device  400 , or by a housing of device  400  itself. In some examples, such as where device  400  is commonly used in electromagnetically isolated environments, electromagnetic shielding may not be necessary at all. In some examples, however, the ability to provide electromagnetic shielding for magnet  416  may be limited where such shielding may interfere with magnetically sensitive components of device  400 , such as compasses or accelerometers. In such examples, electromagnetic shielding may be configured such that it shields magnet  416  and/or crown  402 , but does not shield other components of device  400 . 
       FIG. 5  illustrates an example electronic circuit  500  in an example magnetic sensing cell (e.g., one of magnetic sensing cells  422 ) according to examples of the disclosure.  FIG. 5  depicts a magnetoresistor  502 —that is, a resistor whose resistance Rsense changes with the flux of a magnetic field at the location of the resistor—in a configuration with a source voltage Vdd at one terminal and an output voltage Vsense at the other terminal. In  FIG. 5 , example magnet  506  (which may correspond to magnet  416  described above) corresponds to a magnetic field represented in  FIG. 5  by magnetic field lines  508 . As described above, magnet  506  may be a permanent magnet or an electromagnet. As the strength of the magnetic field  508  through the magnetoresistor  502  increases—for example, as magnetoresistor  502  moves closer to magnet  506 , such that magnetoresistor  502  intersects a stronger portion of magnetic field  508  (whose strength falls off with the distance from magnet  506 )—Rsense decreases, such that output signal Vsense may increase (e.g., if resistor  502  is placed in a voltage divider configuration) and approach the value of supply voltage Vdd. Conversely, as the strength of the magnetic field  508  through the magnetoresistor  502  decreases—for example, as magnetoresistor  502  moves farther from magnet  506 , such that magnetoresistor  502  intersects a weaker portion of magnetic field  508  (whose strength falls off with the distance from magnet  506 )—Rsense increases, such that output signal Vsense may decrease (e.g., if resistor  502  is placed in series with a second resistor in a voltage divider configuration), or may enter a high-impedance state, with respect to Vdd. In this way, magnetoresistor  502  can be used to generate an electrical signal corresponding to a strength of a magnetic field at its location. Further, in some examples, magnetoresistor  502  and/or circuit  500  may be configured to respond to a direction (not merely a magnitude) of magnetic field  508 , such that Vsense may reflect a strength and/or a direction of the magnetic field at the location of magnetoresistor  502 . 
       FIG. 6  illustrates an example electronic circuit  600  for generating a digital signal corresponding to the output of a magnetic sensing cell according to examples of the disclosure. Stage  610  comprises circuit  500  (which may be associated with one of magnetic sensing cells  422 , as described above) in a Wheatstone bridge configuration with three fixed-value resistors  612  as shown in  FIG. 6 . In some examples, circuit  500  may comprise a selected one of magnetic sensing cells  422  (e.g., a cell selected by switch  616 , which may be any appropriate switching mechanism, such as a multiplexer), while the remainder of the Wheatstone bridge circuitry ( 614 ) in stage  610  may be in integrated circuit  428 . As described above, circuit  500  comprises a magnetoresistor  502  (exhibiting a variable resistance Rsense) connected to a supply voltage Vdd and an output voltage Vsense. In the example Wheatstone bridge configuration shown in  FIG. 6 , stage  610  outputs a pair of voltage signals V 1  and V 2  such that the difference (i.e., V 1 −V 2 ) corresponds to the value Rsense of magnetoresistor  502 . At stage  620  of  FIG. 6  in the example shown, differential voltage signals V 1  and V 2  may enter a filtering stage, for example in which noise is removed from the signal V 1 −V 2 . In the example shown, stage  620  comprises an optional chopper-stabilized amplifier  622  to remove low frequency noise from the differential signal V 1 −V 2 . In some examples, integrated circuit  428  may include the circuitry of stage  620  and may perform the filtering described. Other examples of filtering the differential signal V 1 −V 2  will be apparent; the disclosure is not limited to any particular example of filtering the signal, and in some examples, the signal may not be filtered at all. At stage  630  in the example, differential signals V 1  and V 2  then enter an analog-to-digital converter circuit to output a digital signal Vcell, corresponding to the value Rsense of magnetoresistor  502 . In some examples, integrated circuit  428  may include the circuitry of stage  630  and may perform the analog-to-digital conversion described. Vcell may be provided as input to a processor (e.g., host processor  202 , or a processor included in integrated circuit  428 ) which, as described below, may process one or more values of Vcell to determine a rotational position of crown  402 . 
     In some examples, circuit  600  may be coupled to only a single circuit (e.g., circuit  500  shown in  FIG. 5 ) associated with a single magnetic sensing cell  422 . In other examples, circuit  600  may be selectively coupled to one or more circuits (e.g., circuit  500 ) of a plurality of circuits associated with magnetic sensing cells  422 . For instance, a switching mechanism  616  may couple circuit  500  to Wheatstone bridge circuitry  614 , or to another aspect of circuit  600 . Any suitable switching mechanism  616  may be used. In some examples, switching mechanism  616  may belong to a multiplexer, for example, a multiplexer of integrated circuit  428 ; a multiplexer of processor  202 ; or a discrete multiplexer mounted to rotating member  420 . By using a switching mechanism to selectively couple a subset of magnetic sensing cells  422  to circuit  600  (for instance, by serially cycling through a set of control signals, each corresponding to one or more cells), circuit  600  may be shared among two or more magnetic sensing cells  422 —limiting the need for duplicate or redundant circuitry, and minimizing the power consumption and physical space requirements of circuit  600 . However, in some examples in which speed or throughput are paramount, circuit  600  may limit or forgo such a switching mechanism, and process magnetic sensing cells  422  in parallel. 
       FIGS. 7A-7B  illustrate an example of computing a rotational position of crown  402  using a magnetic sensing cell, according to examples of the disclosure.  FIGS. 7A-7B  depict example magnetic sensing cell  422 A (which may correspond to one of magnetic sensing cells  422  described above) mounted on circular member  420  such that magnetic sensing cell  422 A rotates in rotational direction  418  (relative to device  400 ) as circular member  420  rotates in rotational direction  418 , along with housing  414  of crown  402 , as described above. The rotational position of the cell and the crown is represented in the figures by angle  702 . In the figures, circular member  420  is disposed above magnet  416  which exhibits a magnetic field  417  (which, in this example, is a fixed magnetic field). In  FIG. 7A , circular member  420  is rotationally positioned such that magnetic sensing cell  422 A is at a first position P 1 , in which angle  702  is zero degrees with respect to the vertical, which corresponds to the bottom of circular member  420 . At this rotational position, magnetic sensing cell  422 A is at its closest position to magnet  416 . When magnetic sensing cell  422 A is at position P 1 , magnetic sensing cell  422 A experiences a first magnetic field strength T 1 , corresponding to the strength at position P 1  of the field generated by magnet  416 . Magnetic sensing cell  422 A may thus generate an output signal (e.g., Vsense in electronic circuit  500 ) corresponding to T 1 . In  FIG. 7B , circular member  420  has rotated with respect to its position in  FIG. 7A , such that magnetic sensing cell  422 A is rotationally positioned at a second position P 2 , at which angle  702  is at some angle greater than zero. When magnetic sensing cell  422 A is at position P 2 , magnetic sensing cell  422 A experiences a second magnetic field strength T 2 , corresponding to the strength at position P 2  of the field generated by magnet  416 . Because magnetic sensing cell  422 A is farther from magnet  416  at position P 2  than at position P 1 , the field strength T 2  experienced by the cell is lower than field strength T 1 ; accordingly, in some examples, an output signal (e.g., Vsense in electronic circuit  500 ) may be higher or lower at position P 2  than at position P 1 . In examples where magnetic sensing cell  422 A comprises the example electronic circuit  500  shown in  FIG. 5 , Vsense will be lower at position P 2  than position P 1  to reflect the lower value of T 2  compared to T 1 . 
     In the example described above with respect to  FIGS. 7A-7B , magnetic sensing cell  422 A rotates with circular member  420  (with respect to magnet  416 ) and generates an output signal (e.g., Vsense in electronic circuit  500 ) that corresponds to the angular rotational position  702  of magnetic sensing cell  422 A. Because magnetic sensing cell  422 A is fixed relative to circular member  420  in this example, the rotational position of circular member  420  (and thus crown  402 , which rotates with circular member  420 ) can be determined from the output signal. In some examples, this determination may be performed by host processor  202 ; in some examples, it may be performed by a processor included in integrated circuit  428 . 
       FIGS. 8A-8B  depict examples of calculating a rotational position of a crown from an output signal of a magnetic sensing cell, according to examples of the disclosure. The calculations depicted in the examples could be implemented in a processor (e.g., processor  202 , or a processor included in integrated circuit  428  attached to circular member  420 ) that accepts as input the output of a magnetic sensing cell (e.g., the signal Vcell described above with respect to  FIG. 6 ). In the example shown in  FIG. 8A , the processor can communicate with a memory that includes a first table  802  comprising a mapping of input signal (e.g., Vcell) values to rotational positions of magnetic sensor cells (e.g., magnetic sensor cell  422 A), and a second table  804  comprising a mapping of rotational positions of magnetic sensor cell  422 A to the rotational position of crown  402 . The processor can look up the nearest value of Vcell in table  802  to determine a rotational position of magnetic sensor cell  422 A, and then look up the nearest rotational position of magnetic sensor cell  422 A in table  804  to determine a rotational position of crown  402 . In another example, shown in  FIG. 8B , the processor may be configured to apply a function  806  to directly convert an input signal (e.g., Vcell) to a rotational position of crown  402 . Other techniques for determining the rotational position of crown  402  from Vcell will be apparent, and the disclosure is not limited to any particular technique. 
     In the above example described, which utilizes only a single magnetic sensing cell  422 A, the ability to determine the rotational position of crown  402  may be limited by the ability (e.g., the ability of a processor and/or memory) to correlate an output signal of the magnetic sensing cell to a rotational position of that cell. This ability may be limited in configurations where, for example, magnetic sensing cell  422 A does not exhibit a unique output signal for each rotational position of the cell (e.g., where magnet  416  is not sufficiently strong to interact with the magnetic sensing cell at rotational positions farthest from the magnet); where the relationship between the cell output and some rotational positions (e.g., rotational positions farthest from the magnet) is rendered unreliable by electromagnetic interference; or where the signal-to-noise ratio of the magnetic sensing cell output is too low for the cell output to be reliably measured. Further, utilizing only a single magnetic sensing cell may limit the dynamic range of the sensor beyond what is desirable for some applications, or may result in insufficiently linear response. These problems can be addressed by utilizing an array of multiple magnetic sensing cells (e.g., cells  422 A- 422 H in  FIG. 4A ), computing a plurality of rotational positions corresponding to the multiple cells, and using the plurality of rotational positions to determine the rotational position of crown  402 . 
       FIG. 9  depicts an example of determining a rotational position of a crown using a plurality of magnetic sensing cells, according to examples of the disclosure. In some examples, this determination may be performed by host processor  202 ; in some examples, the determination may be performed by a processor of integrated circuit  428 . In the example shown in  FIG. 9 , each of an array  422  of magnetic sensing cells  422 A- 422 H is associated with an index value i, and Vcell[i] represents an output signal Vcell corresponding to the cell associated with index i. Various ways of associating a magnetic sensing cell with an index value will be apparent. For example, the output signals (e.g., Vsense) of an array of magnetic sensing cells may be connected to the inputs of an analog multiplexer, with a processor supplying a binary value corresponding to index i as one or more control signals to the multiplexer. For instance, a value corresponding to index i could be provided to a decoder, such that the decoder outputs a corresponding address signal to the multiplexer. 
     At stage  902 , a value of Vcell[i] can be determined, for example as described above with respect to  FIG. 6 , for each cell in the array  422 . In some examples, this determination may be performed by host processor  202 ; in some examples, the determination may be performed by a processor of integrated circuit  428 . Values of Vcell[i] can be provided to a processor (e.g., processor  202 , or a processor included in integrated circuit  428  attached to circular member  420 ) as described above. At stage  904 , the processor can scan (e.g., using a multiplexer) through all values of Vcell[i] corresponding to the cells in array  422 . At stage  906 , the processor can identify, based on the values of Vcell[i], which of the cells in array  422  is closest to magnet  416  (e.g., in the example shown in  FIG. 9 , by determining which value of Vcell is the highest and therefore corresponds to the strongest magnetic field through that cell). By knowing the rotational position of each of the cells in array  422  with respect to the crown  402 , the processor can thus determine, at stage  908 , the rotational position of crown  402  based on which cell is closest to magnet  416 . For example, the processor might identify the cell with index  3  as closest to magnet  416 , and thus near the bottom rotational position of crown  402 . In the example, the processor can use a lookup table  910 , identifying the rotational position of each cell with respect to the rotational position of the crown, to determine that since cell  422 B is at the bottom rotational position of crown  402 , crown  402  must be oriented at 30.5 degrees relative to some base position. The accuracy of the example may be increased by increasing the number of magnetic sensing cells in array  422 . Furthermore, because each Vsense signal from a corresponding sensor can be physically connected to a specific multiplexer input, the corresponding position of crown  402  associated with each index i can provide an absolute rotational position of the crown. 
       FIG. 10  illustrates an example computing system  1000  for implementing rotational input sensing according to examples of the disclosure. Computing system  1000  can be included in, for example, electronic device  100  or any mobile or non-mobile computing device and/or wearable device that includes a crown  1008  (which can correspond to crown  108  above). Computing system  1000  can include a touch sensing system including one or more touch processors  1002 , touch controller  1006  and touch screen  1014 . Touch screen  1014  can be a touch screen adapted to sense touch inputs, as described in this disclosure. Touch controller  1006  can include circuitry and/or logic configured to sense touch inputs on touch screen  1014 . In some examples, touch controller  1006  and touch processor  1002  can be integrated into a single application specific integrated circuit (ASIC). 
     Computing system  1000  can also include host processor  1010  for receiving outputs from touch processor  1002  and performing actions based on the outputs. Host processor  1010  can be connected to program storage  1012 . For example, host processor  1010  can contribute to generating an image on touch screen  1014  (e.g., by controlling a display controller to display an image of a user interface (UI) on the touch screen), and can use touch processor  1002  and touch controller  1006  to detect one or more touches on or near touch screen  1014 . Host processor  1010  can also contribute to sensing and/or processing mechanical inputs (e.g., rotation, tilting, displacement, etc.) from a crown  1008  (which can be a type of mechanical input mechanism) that can be detected by an encoder  1004  (which can correspond to encoder  204  above). The touch inputs from touch screen  1014  and/or mechanical inputs from the crown  1008  can be used by computer programs stored in program storage  1012  to perform actions in response to the touch and/or mechanical inputs. For example, touch inputs can be used by computer programs stored in program storage  1012  to perform actions that can include moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, placing a telephone call, and other actions that can be performed in response to touch inputs. Mechanical inputs from a mechanical input mechanism can be used by computer programs stored in program storage  1012  to perform actions that can include changing a volume level, locking the touch screen, turning on the touch screen, taking a picture, navigating through three-dimensional menus and environments, and other actions that can be performed in response to mechanical inputs. Host processor  1010  can also perform additional functions that may not be related to touch and/or mechanical input processing. 
     Note that one or more of the functions described above can be performed by firmware stored in memory in computing system  1000  and executed by touch processor  1002 , or stored in program storage  1012  and executed by host processor  1010 . The firmware can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer-readable storage medium” can be any medium (excluding signals) that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
     Therefore, according to the above, some examples of the disclosure are directed to an electronic device configured to be worn by a user comprising: a crown operatively coupled to a body of the electronic device and configured to rotate in a first direction with respect to the body of the electronic device in response to a mechanical input provided by the user, the crown comprising a housing; a rotating member disposed at least partially inside the housing and configured to rotate in the first direction in response to the mechanical input; a first magnetic sensing cell attached to the rotating member at a first location of the rotating member and electrically connected to a first electronic circuit; and a magnet configured to remain stationary with respect to the body of the electronic device; wherein the first electronic circuit is configured to generate a first signal corresponding to a rotational position of the crown with respect to the body of the electronic device. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first magnetic sensing cell is configured to provide to the first electronic circuit a signal corresponding to a strength, at a position of the first magnetic sensing cell, of a magnetic field corresponding to the magnet. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first electronic circuit is attached to the rotating member and configured to rotate in the first direction in response to the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the magnet is disposed at least partially inside the body of the electronic device. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the magnet is disposed at least partially inside the housing. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the housing comprises a circular groove, the magnet is disposed partially inside the circular groove, and the housing is configured to rotate around the magnet. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the electronic device further comprises a second magnetic sensing cell attached to the rotating member at a second location of the rotating member and electrically coupled to a switching mechanism, wherein: the switching mechanism is configured to selectively couple one of the first magnetic sensing cell and the second magnetic sensing cell to the first electronic circuit. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the electronic device further comprises a processor configured to: determine a first magnetic field strength based on a signal from the first magnetic sensing cell; determine a second magnetic field strength based on a signal from the second magnetic sensing cell; and in accordance with a determination that the first magnetic field strength is greater than the second magnetic field strength, determine the rotational position of the crown with respect to the body of the electronic device. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the processor is attached to the rotating member. 
     Some examples of the disclosure are directed to a method of generating a signal corresponding to a rotational position of a crown operatively coupled to a body of an electronic device configured to be worn by a user, the crown comprising a housing, the method comprising: receiving, at an electronic circuit from a first magnetic sensing cell, a first signal corresponding to a position of the first magnetic sensing cell with respect to a magnet configured to remain stationary with respect to the body of the electronic device, wherein: the first magnetic sensing cell is attached to a rotating member disposed at least partially inside the housing, the crown is configured to rotate in a first direction in response to a mechanical input provided by the user, and the rotating member is configured to rotate in the first direction in response to the mechanical input; and generating, at the electronic circuit based on the first signal, a second signal corresponding to a rotational position of the crown with respect to the body of the electronic device. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first signal corresponds to a strength, at a position of the first magnetic sensing cell, of a magnetic field corresponding to the magnet. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the first electronic circuit is attached to the rotating member and configured to rotate in the first direction in response to the mechanical input. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the magnet is disposed at least partially inside the body of the electronic device. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the magnet is disposed at least partially inside the housing. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the housing comprises a circular groove, the magnet is disposed partially inside the circular groove, and the housing is configured to rotate around the magnet. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a second magnetic sensing cell is attached to the rotating member at a second location of the rotating member and electrically coupled to a switching mechanism, and the switching mechanism is configured to selectively couple one of the first magnetic sensing cell and the second magnetic sensing cell to the first electronic circuit. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises determining a first magnetic field strength based on a signal from the first magnetic sensing cell; determining a second magnetic field strength based on a signal from the second magnetic sensing cell; and in accordance with a determination that the first magnetic field strength is greater than the second magnetic field strength, determining the rotational position of the crown with respect to the body of the electronic device. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the electronic circuit comprises a processor attached to the rotating member. 
     Some examples of the disclosure are directed to an electronic device configured to be worn by a user comprising: means for rotating a crown in a first direction with respect to a body of the electronic device in response to a mechanical input provided by the user; first magnetic sensing means for detecting a first strength of a magnetic field corresponding to a magnet; second magnetic sensing means for detecting a second strength of the magnetic field corresponding to the magnet; means for selectively coupling one of the first magnetic sensing means and the second magnetic sensing means to an electronic circuit; and means for determining, based on an output of the first magnetic sensing means and an output of the second magnetic sensing means, a rotational position of the crown with respect to the body of the electronic device, wherein: the first magnetic sensing means and the second magnetic sensing means are configured to rotate in the first direction in response to the mechanical input provided by the user, and the magnet is configured to remain stationary with respect to the body of the electronic device. 
     Although examples of this disclosure have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of examples of this disclosure as defined by the appended claims.

Metadata:
Filing Date: 20170927
Publication Date: 20191112
Grant Date: 20191112
Priority Date: 20170927
Inventors: GUO, JIAN
Assignee: APPLE INC
CPC Classifications: [{"code": "G04C3/004", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04C3/004", "inventive": true, "first": true, "tree": "[]"}, {"code": "G04G17/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04G17/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "G04C3/004", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 65807454