PATENT DOCUMENT

Publication Number: US-11460933-B2
Application Number: US-202017031549-A
Country: US
Kind Code: B2

Title: Shield electrode for input device

Abstract:
In some examples, a stylus can include a conductive shield. In some examples, the conductive shield can include a plurality of traces along an edge of a printed circuit board (PCB) including the stylus circuitry. In some examples, the conductive shield can include a shield can coupled to the PCB and disposed around the components of the stylus circuitry. In some examples, the conductive shield can include a hollow portion into which the stylus circuitry can be disposed and a solid portion that can act as a reference electrode. In some examples, the conductive shield can include a hollow sleeve disposed around the stylus circuitry. In some examples, the conductive sleeve can be attached to the PCB. In some examples, the conductive sleeve can be disposed between layers of a housing of the stylus. In some examples, the conductive sleeve can be integrated with the stylus housing.

Claims:
What is claimed is: 
     
       1. An input device comprising:
 a housing oriented along an axis; 
 a printed circuit board (PCB) including circuitry, the circuitry disposed within a first distance of the axis and the circuitry including a first portion and a second portion; 
 a tip electrode coupled to the circuitry, the first portion of the circuitry closer to the tip electrode than the second portion of the circuitry; and 
 a conductive element disposed around at least a portion of the circuitry, wherein the conductive element is disposed around the second portion of the circuitry but not around the first portion of the circuitry, wherein the conductive element is disposed within a second distance from the axis that is greater than the first distance, and wherein the circuitry is located along the axis between the tip electrode and the conductive element. 
 
     
     
       2. The input device of  claim 1 , wherein the conductive element includes a conductive sleeve coupled to a side of the PCB that is parallel to the axis. 
     
     
       3. The input device of  claim 1 , wherein the conductive element includes a hollow cylinder in which at least the portion of the circuitry is disposed, the conductive element further comprising a plurality of spring clips mechanically coupled to the PCB. 
     
     
       4. The input device of  claim 1 , wherein:
 the housing includes:
 a first portion disposed a third distance from the axis, the third distance between the first distance and the second distance, and 
 a second portion disposed a fourth distance from the axis, the fourth distance greater than the third distance, and 
 
 the conductive element is disposed between the first and second portions of the housing. 
 
     
     
       5. The input device of  claim 1 , wherein the conductive element is integrated with the housing. 
     
     
       6. An input device comprising:
 a housing oriented along an axis; 
 a printed circuit board (PCB) including circuitry, the circuitry disposed within a first distance of the axis and the circuitry including a first portion and a second portion; 
 a tip electrode coupled to the circuitry, the first portion of the circuitry closer to the tip electrode than the second portion of the circuitry; and 
 a conductive element disposed at a same location along the axis at which at least a portion of the circuitry is disposed, the conductive element being disposed a second distance from the axis that is greater than the first distance, the conductive element being disposed around the second portion of the circuitry but not around the first portion of the circuitry, and wherein the circuitry is located along the axis between the tip electrode and the conductive element. 
 
     
     
       7. The input device of  claim 6 , wherein the conductive element includes a conductive trace disposed at the edge of the PCB. 
     
     
       8. The input device of  claim 6 , wherein the conductive element includes a shield can coupled to the PCB. 
     
     
       9. The input device of  claim 6 , wherein the conductive element includes:
 a hollow cylindrical portion in which the PCB is disposed, and 
 a solid portion disposed at a location along the axis different from the same location along the axis at which at least the portion of the circuitry is disposed. 
 
     
     
       10. The input device of  claim 6 , wherein the conductive element includes a conductive sleeve coupled to a side of the PCB that is parallel to the axis. 
     
     
       11. The input device of  claim 6 , wherein the conductive element includes a hollow cylinder in which at least the portion of the circuitry is disposed, the conductive element further comprising a plurality of spring clips mechanically coupled to the PCB. 
     
     
       12. The input device of  claim 6 , wherein:
 the housing includes:
 a first portion disposed a third distance from the axis, the third distance between the first distance and the second distance, and 
 a second portion disposed a fourth distance from the axis, the fourth distance greater than the third distance, and 
 
 the conductive element is disposed between the first and second portions of the housing. 
 
     
     
       13. The input device of  claim 6 , wherein the conductive element is integrated with the housing. 
     
     
       14. An input device, comprising:
 a housing oriented along an axis; 
 a printed circuit board (PCB) including circuitry, the circuitry disposed within a first distance of the axis and the circuitry including a first portion and a second portion; 
 a tip electrode coupled to the circuitry, the first portion of the circuitry closer to the tip electrode than the second portion of the circuitry; and 
 a conductive sleeve coupled to a side of the PCB and disposed around at least a portion of the circuitry, wherein the conductive sleeve is disposed around the second portion of the circuitry but not around the first portion of the circuitry, wherein the conductive sleeve is disposed within a second distance from the axis that is greater than the first distance, and wherein the circuitry is located along the axis between the tip electrode and the conductive sleeve. 
 
     
     
       15. The input device of  claim 14 , the conductive sleeve includes a plurality of slits perpendicular to the axis. 
     
     
       16. The input device of  claim 14 , wherein the conductive sleeve is parallel to the axis. 
     
     
       17. The input device of  claim 14 , wherein the conductive sleeve is not parallel to the axis.

Description:
FIELD 
     This relates to an input device and, more particularly, to a stylus including a shield electrode. 
     BACKGROUND 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch panels, touch screens and the like. Touch screens, in particular, are popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD), light emitting diode (LED) display or organic light emitting diode (OLED) display 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 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 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 some examples, touch panels can be included in other input devices that are separate from any display screen, such as trackpads. 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 some examples, the electronic device is able to detect objects proximate to or touching a touch-sensitive surface such as a touch screen. For example, the electronic device can detect conductive objects, such as human fingers, palms, and hands and input devices, such as a stylus. In some examples, a stylus can be an active stylus that includes a power supply and generates a stylus signal that can be detected by the electronic device. The electronic device can detect an active stylus by detecting the stylus signal, which can capacitively couple to one or more touch electrodes of the touch-sensitive surface. In some examples, a stylus can be a passive stylus that does not include a power supply. The passive stylus can include one or more conductive components that can capacitively couple to an electrode of the touch screen to produce or modify a signal sensed by the electronic device. For example, a passive stylus may reduce the capacitive coupling between a drive line and a sense line of the touch-sensitive surface by also being capacitively coupled to the drive and sense lines, thereby modifying the signal sensed by the sense line, thus enabling the electronic device to detect the stylus. 
     SUMMARY 
     This disclosure relates to an input device and, more particularly, to a stylus including a shield electrode. In some examples, the stylus can include circuitry that can produce a non-linear response to a periodic drive signal provided by a touch sensitive surface (e.g., a touch screen or trackpad). The stylus can further include a stylus tip electrode coupled to the stylus circuitry and configured to receive the drive signals from the touch sensitive surface and provide the non-linear stylus signal to the touch sensitive surface. In some examples, it is possible for the stylus circuitry to capacitively couple to the touch sensitive surface, which can cause errors in determining the location of the stylus. Thus, in some examples, it can be advantageous to include a conductive shield between the stylus circuitry and the touch sensitive surface to reduce the amount of capacitive coupling between the touch sensitive surface and the stylus circuitry, which can improve the accuracy of detecting the stylus&#39; location. 
     In some examples, the conductive shield can include a plurality of traces along an edge of a printed circuit board (PCB) including the stylus circuitry. In some examples, the conductive shield can include a shield can coupled to the PCB and disposed around the components of the stylus circuitry. In some examples, the conductive shield can include a hollow portion into which the stylus circuitry can be disposed and a solid portion that can act as a reference electrode. In some examples, the conductive shield can include a hollow sleeve disposed around the stylus circuitry. In some examples, the conductive sleeve can be attached to the PCB. In some examples, the conductive sleeve can be disposed between layers of a housing of the stylus. In some examples, the conductive sleeve can be integrated with the stylus housing (e.g., the stylus housing can include a conductive material that acts as a shield). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1E  illustrate example systems that can detect input devices implementing shielding techniques according to examples of the disclosure. 
         FIG. 2  illustrates an example computing system including a touch screen that can be implemented with multi-frequency stylus scans according to examples of the disclosure. 
         FIG. 3A  illustrates an exemplary touch sensor circuit corresponding to a self-capacitance measurement of a touch node electrode and sensing circuit according to examples of the disclosure. 
         FIG. 3B  illustrates an exemplary touch sensor circuit corresponding to a mutual-capacitance drive line and sense line and sensing circuit according to examples of the disclosure. 
         FIG. 4A  illustrates touch screen with touch electrodes arranged in rows and columns according to examples of the disclosure. 
         FIG. 4B  illustrates touch screen with touch node electrodes arranged in a pixelated touch node electrode configuration according to examples of the disclosure. 
         FIG. 5  illustrates an exemplary stylus and exemplary electronic device according to some examples of the disclosure. 
         FIG. 6  illustrates an exemplary stylus according to some examples of the disclosure. 
         FIGS. 7A-7B  illustrate the capacitive coupling of an exemplary stylus to a touch-sensitive surface according to some examples of the disclosure. 
         FIG. 7C  illustrates an exemplary true position and an exemplary detected position of a stylus that is not normal or substantially normal to the touch-sensitive surface according to some examples of the disclosure. 
         FIG. 8A  illustrates an exemplary stylus that includes a printed circuit board (PCB) having shielding traces according to some examples of the disclosure. 
         FIG. 8B  illustrates an exemplary PCB including shield traces according to some examples of the disclosure. 
         FIG. 9A  illustrates an exemplary stylus that includes a PCB having a shield can according to some examples of the disclosure. 
         FIG. 9B  illustrates an exemplary PCB including shield can according to some examples of the disclosure. 
         FIG. 10  illustrates an exemplary stylus that includes a conductive sleeve according to some examples of the disclosure. 
         FIGS. 11A-11O  illustrate an exemplary stylus that includes a conductive sleeve  1106  according to some examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and 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 used and structural changes can be made without departing from the scope of the disclosed examples. 
     This disclosure relates to an input device and, more particularly, to a stylus including a shield electrode. In some examples, the stylus can include circuitry that can produce a non-linear response to a periodic drive signal provided by a touch sensitive surface (e.g., a touch screen or trackpad). The stylus can further include a stylus tip electrode coupled to the stylus circuitry and configured to receive the drive signals from the touch sensitive surface and provide the non-linear stylus signal to the touch sensitive surface. In some examples, it is possible for the stylus circuitry to capacitively couple to the touch sensitive surface, which can cause errors in determining the location of the stylus. Thus, in some examples, it can be advantageous to include a conductive shield between the stylus circuitry and the touch sensitive surface to reduce the amount of capacitive coupling between the touch sensitive surface and the stylus circuitry, which can improve the accuracy of detecting the stylus&#39; location. 
     In some examples, the conductive shield can include a plurality of traces along an edge of a printed circuit board (PCB) including the stylus circuitry. In some examples, the conductive shield can include a shield can coupled to the PCB and disposed around the components of the stylus circuitry. In some examples, the conductive shield can include a hollow portion into which the stylus circuitry can be disposed and a solid portion that can act as a reference electrode. In some examples, the conductive shield can include a hollow sleeve disposed around the stylus circuitry. In some examples, the conductive sleeve can be attached to the PCB. In some examples, the conductive sleeve can be disposed between layers of a housing of the stylus. In some examples, the conductive sleeve can be integrated with the stylus housing (e.g., the stylus housing can include a conductive material that acts as a shield). 
       FIGS. 1A-1E  illustrate example systems that can detect input devices implementing shielding techniques according to examples of the disclosure.  FIG. 1A  illustrates an example mobile telephone  136  that includes a touch screen  124  that can detect input devices implementing shielding techniques according to examples of the disclosure.  FIG. 1B  illustrates an example digital media player  140  that includes a touch screen  126  that can detect input devices implementing shielding techniques according to examples of the disclosure.  FIG. 1C  illustrates an example personal computer  144  that includes a touch screen  128  that can detect input devices implementing shielding techniques according to examples of the disclosure.  FIG. 1D  illustrates an example tablet computing device  148  that includes a touch screen  130  that can detect input devices implementing shielding techniques according to examples of the disclosure.  FIG. 1E  illustrates an example wearable device  150  that includes a touch screen  132  and can be attached to a user using a strap  152  and that can detect input devices implementing shielding techniques according to examples of the disclosure. It is understood that other devices can include a touch screen and detect input devices implementing shielding techniques. Additionally it should be understood that although the disclosure herein primarily focuses on touch screens, the disclosure of detecting input devices implementing shielding techniques can be implemented for devices including touch sensor panels (and displays) that may not be implemented as a touch screen. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130  and  132  can be based on self-capacitance. A self-capacitance based touch system can include a matrix of small, individual plates of conductive material or groups of individual plates of conductive material forming larger conductive regions that can be referred to as touch electrodes or as touch node electrodes (as described below with reference to  FIG. 4B ). For example, a touch screen can include a plurality of touch electrodes, each touch electrode identifying or representing a unique location (e.g., a touch node) on the touch screen at which touch or proximity is to be sensed, and each touch node electrode being electrically isolated from the other touch node electrodes in the touch screen/panel. Such a touch screen can be referred to as a pixelated self-capacitance touch screen, though it is understood that in some examples, the touch node electrodes on the touch screen can be used to perform scans other than self-capacitance scans on the touch screen (e.g., mutual capacitance scans). During operation, a touch node electrode can be stimulated with an alternating current (AC) waveform, and the self-capacitance to ground of the touch node electrode can be measured. As an object approaches the touch node electrode, the self-capacitance to ground of the touch node electrode can change (e.g., increase). This change in the self-capacitance of the touch node electrode can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. In some examples, the touch node electrodes of a self-capacitance based touch system can be formed from rows and columns of conductive material, and changes in the self-capacitance to ground of the rows and columns can be detected, similar to above. In some examples, a touch screen can be multi-touch, single touch, projection scan, full-imaging multi-touch, capacitive touch, etc. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130  and  132  can be based on mutual capacitance. A mutual capacitance based touch system can include electrodes arranged as drive and sense lines that may cross over each other (e.g., as described below with reference to  FIG. 4A ) on different layers (in a double-sided configuration), or may be adjacent to each other on the same layer. The crossing or adjacent locations can form touch nodes. During operation, the drive line can be stimulated with an AC waveform and the mutual capacitance of the touch node can be measured. As an object approaches the touch node, the mutual capacitance of the touch node can change (e.g., decrease). This change in the mutual capacitance of the touch node can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. As described herein, in some examples, a mutual capacitance based touch system can form touch nodes from a matrix of small, individual plates of conductive material. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130  and  132  can be based on mutual capacitance and/or self-capacitance. The electrodes can be arranged as a matrix of small, individual plates of conductive material (e.g., as in touch node electrodes  408  in touch screen  402  in  FIG. 4B ) or as drive lines and sense lines (e.g., as in row touch electrodes  404  and column touch electrodes  406  in touch screen  400  in  FIG. 4A ), or in another pattern. The electrodes can be configurable for mutual capacitance or self-capacitance sensing or a combination of mutual and self-capacitance sensing. For example, in one mode of operation electrodes can be configured to sense mutual capacitance between electrodes and in a different mode of operation electrodes can be configured to sense self-capacitance of electrodes. In some examples, some of the electrodes can be configured to sense mutual capacitance therebetween and some of the electrodes can be configured to sense self-capacitance thereof. 
     In some examples, touch screens  124 ,  126 ,  128 ,  130 , and  132  can sense an active stylus. The active stylus can produce a stylus signal that can capacitively couple to the touch electrodes of touch screen  124 ,  126 ,  128 ,  130 , and  132  to be sensed by sense circuitry coupled to the touch electrodes. In some examples, a touch screen including touch node electrodes  408  can determine the location of the stylus by determining which touch node electrodes  408  detect the stylus signal. In some examples, a touch screen including row electrodes  404  and column electrodes  406  can determine the location of the stylus along the rows and along the columns to determine the location of the stylus on the touch screen. Touch screens can be configured to detect both passive conductive objects (e.g., fingers, passive styluses) and active styluses. For example, the electronic device can perform a mutual or self capacitance scan to detect the conductive objects (e.g., perform a “touch scan”) and perform stylus scans to detect the active stylus. 
       FIG. 2  illustrates an example computing system including a touch screen that can use multi-frequency stylus scans according to examples of the disclosure. Computing system  200  can be included in, for example, a mobile phone, tablet, touchpad, portable or desktop computer, portable media player, wearable device or any mobile or non-mobile computing device that includes a touch screen or touch sensor panel. Computing system  200  can include a touch sensing system including one or more touch processors  202 , peripherals  204 , a touch controller  206 , and touch sensing circuitry (described in more detail below). Peripherals  204  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Touch controller  206  can include, but is not limited to, one or more sense channels  208  (e.g., including one or more of sensing circuit  314 ), channel scan logic  210  and driver logic  214 . Channel scan logic  210  can access RAM  212 , autonomously read data from the sense channels and provide control for the sense channels. In addition, channel scan logic  210  can control driver logic  214  to generate stimulation signals  216  at various frequencies and/or phases that can be selectively applied to drive regions of the touch sensing circuitry of touch screen  220  (e.g., to drive line  322  or touch node electrode  302  directly or via touch sensing circuit  314 ), as described in more detail below. In some examples, touch controller  206 , touch processor  202  and peripherals  204  can be integrated into a single application specific integrated circuit (ASIC), and in some examples can be integrated with touch screen  220  itself. 
     It should be apparent that the architecture shown in  FIG. 2  is only one example architecture of computing system  200 , and that the system could have more or fewer components than shown, or a different configuration of components. The various components shown in  FIG. 2  can be implemented in hardware, software, firmware or any combination thereof, including one or more signal processing and/or application specific integrated circuits. 
     Computing system  200  can include a host processor  228  for receiving outputs from touch processor  202  and performing actions based on the outputs. For example, host processor  228  can be connected to program storage  232  and a display controller/driver  234  (e.g., a Liquid-Crystal Display (LCD) driver). It is understood that although some examples of the disclosure may be described with reference to LCD displays, the scope of the disclosure is not so limited and can extend to other types of displays, such as Light-Emitting Diode (LED) displays, including Organic LED (OLED), Active-Matrix Organic LED (AMOLED) and Passive-Matrix Organic LED (PMOLED) displays. Display driver  234  can provide voltages on select (e.g., gate) lines to each pixel transistor and can provide data signals along data lines to these same transistors to control the pixel display image. 
     Host processor  228  can use display driver  234  to generate a display image on touch screen  220 , such as a display image of a user interface (UI), and can use touch processor  202  and touch controller  206  to detect a touch on or near touch screen  220 , such as a touch input to the displayed UI. The touch input can be used by computer programs stored in program storage  232  to perform actions that can include, but are not limited to, 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, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. Host processor  228  can also perform additional functions that may not be related to touch processing. 
     Note that one or more of the functions described herein, including multi-frequency stylus scans, can be performed by firmware stored in memory (e.g., one of the peripherals  204  in  FIG. 2 ) and executed by touch processor  202  and/or touch controller  206 , or stored in program storage  232  and executed by host processor  228 . 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. In some examples, RAM  212  or program storage  232  (or both) can be a non-transitory computer readable storage medium. One or both of RAM  212  and program storage  232  can have stored therein instructions, which when executed by touch processor  202  or host processor  228  or both, can cause the device including computing system  200  to perform one or more functions and methods of one or more examples of this disclosure. 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. 
     Touch screen  220  can be used to derive touch information at multiple discrete locations of the touch screen, referred to herein as touch nodes. Touch screen  220  can include touch sensing circuitry that can include a capacitive sensing medium having a plurality of drive lines  222  and a plurality of sense lines  223 . It should be noted that the term “lines” is sometimes used herein to mean simply conductive pathways, as one skilled in the art will readily understand, and is not limited to elements that are strictly linear, but includes pathways that change direction, and includes pathways of different size, shape, materials, etc. Drive lines  222  can be driven by stimulation signals  216  from driver logic  214  through a drive interface  224 , and resulting sense signals  217  generated in sense lines  223  can be transmitted through a sense interface  225  to sense channels  208  in touch controller  206 . In this way, drive lines and sense lines can be part of the touch sensing circuitry that can interact to form capacitive touch nodes, which can be thought of as touch picture elements (touch pixels) and referred to herein as touch nodes, such as touch nodes  226  and  227 . This way of understanding can be particularly useful when touch screen  220  is viewed as capturing an “image” of touch (“touch image”). In other words, after touch controller  206  has determined whether a touch has been detected at each touch nodes in the touch screen, the pattern of touch nodes in the touch screen at which a touch occurred can be thought of as an “image” of touch (e.g., a pattern of fingers touching the touch screen). As used herein, an electrical component “coupled to” or “connected to” another electrical component encompasses a direct or indirect connection providing electrical path for communication or operation between the coupled components. Thus, for example, drive lines  222  may be directly connected to driver logic  214  or indirectly connected to drive logic  214  via drive interface  224  and sense lines  223  may be directly connected to sense channels  208  or indirectly connected to sense channels  208  via sense interface  225 . In either case an electrical path for driving and/or sensing the touch nodes can be provided. 
       FIG. 3A  illustrates an exemplary touch sensor circuit  300  corresponding to a self-capacitance measurement of a touch node electrode  302  and sensing circuit  314  (e.g., implemented in the one or more sense channels  208 ) according to examples of the disclosure. Touch node electrode  302  can correspond to a touch electrode  404  or  406  of touch screen  400  or a touch node electrode  408  of touch screen  402 . Touch node electrode  302  can have an inherent self-capacitance to ground associated with it, and also an additional self-capacitance to ground that is formed when an object, such as finger  305 , is in proximity to or touching the electrode. The total self-capacitance to ground of touch node electrode  302  can be illustrated as capacitance  304 . Touch node electrode  302  can be coupled to sensing circuit  314 . Sensing circuit  314  can include an operational amplifier  308 , feedback resistor  312  and feedback capacitor  310 , although other configurations can be employed. For example, feedback resistor  312  can be replaced by a switched capacitor resistor in order to minimize a parasitic capacitance effect that can be caused by a variable feedback resistor. Touch node electrode  302  can be coupled to the inverting input (−) of operational amplifier  308 . An AC voltage source  306  (V ac ) can be coupled to the non-inverting input (+) of operational amplifier  308 . Touch sensor circuit  300  can be configured to sense changes (e.g., increases) in the total self-capacitance  304  of the touch node electrode  302  induced by a finger or object either touching or in proximity to the touch sensor panel. Output  320  can be used by a processor to determine the presence of a proximity or touch event, or the output can be inputted into a discrete logic network to determine the presence of a proximity or touch event. 
       FIG. 3B  illustrates an exemplary touch sensor circuit  350  corresponding to a mutual-capacitance drive line  322  and sense line  326  and sensing circuit  314  (e.g., implemented in the one or more sense channels  208 ) according to examples of the disclosure. Drive line  322  can be stimulated by stimulation signal  306  (e.g., an AC voltage signal). Stimulation signal  306  can be capacitively coupled to sense line  326  through mutual capacitance  324  between drive line  322  and the sense line. When a finger or object  305  approaches the touch node created by the intersection of drive line  322  and sense line  326 , mutual capacitance  324  can change (e.g., decrease). This change in mutual capacitance  324  can be detected to indicate a touch or proximity event at the touch node, as described herein. The sense signal coupled onto sense line  326  can be received by sensing circuit  314 . Sensing circuit  314  can include operational amplifier  308  and at least one of a feedback resistor  312  and a feedback capacitor  310 .  FIG. 3B  illustrates a general case in which both resistive and capacitive feedback elements are utilized. The sense signal (referred to as V in ) can be inputted into the inverting input of operational amplifier  308 , and the non-inverting input of the operational amplifier can be coupled to a reference voltage V ref . Operational amplifier  308  can drive its output to voltage Vo to keep yin substantially equal to V ref , and can therefore maintain V in  constant or virtually grounded. A person of skill in the art would understand that in this context, equal can include deviations of up to 15%. Therefore, the gain of sensing circuit  314  can be mostly a function of the ratio of mutual capacitance  324  and the feedback impedance, comprised of resistor  312  and/or capacitor  310 . The output of sensing circuit  314  Vo can be filtered and heterodyned or homodyned by being fed into multiplier  328 , where Vo can be multiplied with local oscillator  330  to produce V detect . V detect  can be inputted into filter  332 . One skilled in the art will recognize that the placement of filter  332  can be varied; thus, the filter can be placed after multiplier  328 , as illustrated, or two filters can be employed: one before the multiplier and one after the multiplier. In some examples, there can be no filter at all. The direct current (DC) portion of V detect  can be used to determine if a touch or proximity event has occurred. Note that while  FIGS. 3A-3B  indicate the demodulation at multiplier  328  occurs in the analog domain, output Vo may be digitized by an analog-to-digital converter (ADC), and blocks  328 ,  332  and  330  may be implemented in a digital fashion (e.g.,  328  can be a digital demodulator,  332  can be a digital filter, and  330  can be a digital NCO (Numerical Controlled Oscillator). 
     In some examples, a stylus signal can be detected using touch sensor circuit  350  or similar circuitry. Instead of the drive circuitry providing a stimulation signal (e.g., via AC stimulation source  306 ) to drive lines  322 , the stylus can provide a stylus signal that capacitively couples to sense line  326 . The coupled signal can be sensed by sensing circuit  314 . In some examples, because the stylus provides the stimulation signal, row electrodes and column electrodes (drive lines and sense lines in the mutual capacitance touch sensing) can be coupled to sensing circuits and can be sensed. For example, the electronic device can perform one or more scans to sense the row electrodes during a first time and can then perform one or more scans to sense the column electrodes during a second time. In some examples, the row electrodes and column electrodes can be sensed simultaneously. In some examples, a touch screen  402  including touch node electrodes  408  can sense an active stylus in a similar manner (e.g., each can be coupled to a sensing circuit  314 . Additional examples of active styluses and sensing active styluses are described below with reference to  FIGS. 5 and 6 . 
     Referring back to  FIG. 2 , in some examples, touch screen  220  can be an integrated touch screen in which touch sensing circuit elements of the touch sensing system can be integrated into the display pixel stack-ups of a display. The circuit elements in touch screen  220  can include, for example, elements that can exist in LCD or other displays (LED display, OLED display, etc.), such as one or more pixel transistors (e.g., thin film transistors (TFTs)), gate lines, data lines, pixel electrodes and common electrodes. In a given display pixel, a voltage between a pixel electrode and a common electrode can control a luminance of the display pixel. The voltage on the pixel electrode can be supplied by a data line through a pixel transistor, which can be controlled by a gate line. It is noted that circuit elements are not limited to whole circuit components, such as a whole capacitor, a whole transistor, etc., but can include portions of circuitry, such as only one of the two plates of a parallel plate capacitor. 
       FIG. 4A  illustrates touch screen  400  with touch electrodes  404  and  406  arranged in rows and columns according to examples of the disclosure. Specifically, touch screen  400  can include a plurality of touch electrodes  404  disposed as rows, and a plurality of touch electrodes  406  disposed as columns. Touch electrodes  404  and touch electrodes  406  can be on the same or different material layers on touch screen  400 , and can intersect with each other, as illustrated in  FIG. 4A . In some examples, the electrodes can be formed on opposite sides of a transparent (partially or fully) substrate and from a transparent (partially or fully) semiconductor material, such as ITO, though other materials are possible. Electrodes displayed on layers on different sides of the substrate can be referred to herein as a double-sided sensor. In some examples, touch screen  400  can sense the self-capacitance of touch electrodes  404  and  406  to detect touch and/or proximity activity on touch screen  400 , and in some examples, touch screen  400  can sense the mutual capacitance between touch electrodes  404  and  406  to detect touch and/or proximity activity on touch screen  400 . In some examples, touch screen  400  can sense a stylus signal provided by an active stylus using touch electrodes  404  and  406 . 
       FIG. 4B  illustrates touch screen  402  with touch node electrodes  408  arranged in a pixelated touch node electrode configuration according to examples of the disclosure. Specifically, touch screen  402  can include a plurality of individual touch node electrodes  408 , each touch node electrode identifying or representing a unique location on the touch screen at which touch or proximity (i.e., a touch or proximity event) is to be sensed, and each touch node electrode being electrically isolated from the other touch node electrodes in the touch screen/panel, as previously described. Touch node electrodes  408  can be on the same or different material layers on touch screen  402 . In some examples, touch screen  402  can sense the self-capacitance of touch node electrodes  408  to detect touch and/or proximity activity on touch screen  402 , and in some examples, touch screen  402  can sense the mutual capacitance between touch node electrodes  408  to detect touch and/or proximity activity on touch screen  402 . In some examples, touch screen  402  can use touch electrodes  408  to sense an active stylus. 
       FIG. 5  illustrates an exemplary system including a stylus  520  and an electronic device  500  according to some examples of the disclosure. Stylus  520  (e.g., a marking tool, smart pen, smart brush, wand, chisel, user-manipulated electronic input device, hand-held input device, and the like, or any other suitable accessory, such as a glove) may be configured to provide input to electronic device  500  (e.g., a tablet computer, laptop computer, desktop computer, and the like). A system user may manipulate the orientation and position of stylus  520  relative to a surface of the touch-sensitive display of electronic device  500  to convey information to electronic device  500 , such as, but not limited to, writing, sketching, scrolling, gaming, selecting user interface elements, moving user interface elements, and so on. In some examples, the surface of the touch-sensitive display of electronic device  500  may be a multi-touch display screen. However, in some examples, the surface of the touch-sensitive display of electronic device  500  may be a non-display surface of the touch-sensitive display, such as, but not limited to, a trackpad or drawing tablet. The surface of the touch-sensitive display may be a foldable or flexible surface or display. Electronic device  500  may be used to capture free-form user input from stylus  520 . For example, the user can slide, move, draw, or drag a tip of stylus  520  across the surface of the touch-sensitive display of electronic device  500 , which, in response, may render a graphical object (e.g., a line) using a display positioned below the surface of the touch-sensitive display. In such an example, the rendered graphical object may follow or otherwise correspond to the path of stylus  520  across the surface of the touch-sensitive display of electronic device  500 . The thickness and/or shape and/or intensity and/or any other suitable rendered characteristic of the rendered graphical object may vary based, at least in part, on one, some, or each of various characteristics, including, but not limited to, a force or speed with which the user moves stylus  520  across the surface of the touch-sensitive display, an angle of stylus  520  relative to the surface of the touch-sensitive display (e.g., the inclination of stylus  520  relative to a plane of the surface of the touch-sensitive display, a writing angle of stylus  520  relative to a horizontal writing line traversing the surface of the touch-sensitive display, etc.), a variable setting of a variable input component of stylus  520 , which one of multiple tips of stylus  520  is interacting with the surface of the touch-sensitive display, a variable setting of an application running on electronic device  500  (e.g., a virtual drawing space application), and/or a combination thereof. 
     Broadly and generally, electronic device  500  may be operative to determine and/or estimate one or more outputs of stylus  520  (and/or changes therein over time as a scalar or vector quantity), to interpret the user&#39;s manipulation thereof as input to electronic device  500 . For example, electronic device  500  may be operative to estimate: the magnitude of force applied by a user&#39;s grip to stylus  520  (e.g., non-binary estimate of magnitude as a scalar or vector quantity); a magnitude (e.g., non-binary estimate of magnitude as a scalar or vector quantity) of force applied (e.g., force applied Fa) by stylus  520  to the surface of the touch-sensitive display of electronic device  500 ; the location at which the area over which stylus  520  may touch or nearly touch the surface of the touch-sensitive display of electronic device  500 ; a polar angle of stylus  520  relative to a plane of the surface of the touch-sensitive display (e.g., inclination of stylus  520  (e.g., a polar angle  518  (e.g., as may be defined between a vector normal to the plane of surface of the touch-sensitive display  511   a  and a longitudinal axis  526  of stylus  520 , such as a zenith))); an azimuthal angle of stylus  520  relative to an axis of the surface of the touch-sensitive display (e.g., an azimuthal angle  523  (e.g., as may be defined between the polar angle  518  and a reference vector within the plane of surface of the touch-sensitive display  510   a , such as an axis of electronic device  500 )); a vector or scalar representation of the angular position of stylus  520  relative to a plane of the surface of the touch-sensitive display; three-dimensional coordinates (e.g., spherical, Cartesian, and so on) of one or more points along the length of stylus  520  relative to the surface of the touch-sensitive display; and so on. In some examples, electronic device  500  may be operative to monitor such variables over time to estimate rates of change therein as either scalar or vector quantities (e.g., velocity, acceleration, and so on). The operation of estimating or determining two-dimensional position coordinates of stylus  520  as a point (or area) within or parallel to a plane of the surface of the touch-sensitive display, whether such operation is performed by electronic device  500 , performed by stylus  520 , and/or performed, at least in part, as a result of cooperation there between (or with one or more other electronic devices), is generally referred to herein as “locating” the stylus. 
     Electronic device  500  and/or stylus  520  can be configured to estimate and/or monitor the location of stylus  520  over time and compute differential or integral quantities such as, but not limited to, acceleration, velocity, total force applied, path length, and so on. For example, the operation of estimating the velocity and/or acceleration of stylus  520  relative to the surface of the touch-sensitive display as stylus  520  is moved across that surface, whether such operation is performed by electronic device  500 , performed by stylus  520 , and/or performed, at least in part, as a result of cooperation therebetween (or with one or more other electronic devices), is generally referred to herein as estimating the “planar motion” of the stylus. The operation of estimating the angular velocity and/or acceleration of stylus  520  relative to a plane of the surface of the touch-sensitive display as it is moved thereacross, whether performed by electronic device  500 , performed by stylus  520 , and/or performed, at least in part, as a result of cooperation therebetween (or with one or more other electronic devices), is generally referred to herein as estimating the “angular motion” of the stylus. Additionally or alternatively, electronic device  500  and/or stylus  520  can be configured to estimate the distance (e.g., Z-height) of a portion of stylus  520  (e.g., the tip of the stylus) from the surface of the touch-sensitive display of device  500 , and such an estimated distance may be used to determine a “make or break” event between the stylus and device, such as for making a determination when a drawn graphical line should start or stop or a stylus lift off event should occur. 
     Electronic device  500  may be any portable, mobile, or hand-held electronic device configured to interact with stylus  520  for changing any suitable characteristic(s) of device  500  (e.g., any suitable graphical object input tool characteristics that may be utilized to render a graphical object) in response to manipulation of stylus  520  across a surface of the touch-sensitive display of electronic device  500 . Alternatively, electronic device  500  may not be portable at all, but may instead be generally stationary. Electronic device  500  can include, but is not limited to, a media player, video player, still image player, game player, other media player, music recorder, movie or video camera or recorder, still camera, other media recorder, radio, medical equipment, domestic appliance, transportation vehicle instrument, musical instrument, calculator, cellular telephone, other wireless communication device, personal digital assistant, remote control, pager, computer (e.g., a desktop, laptop, tablet, server, etc.), merchant accessory (e.g., signature pad (e.g., as may be used in a check-out line of a merchant store during payment processing)), monitor, television, stereo equipment, set up box, set-top box, wearable device (e.g., watch, clothing, etc.), boom box, modem, router, printer, and combinations thereof. Electronic device  500  may include one or more components described above with reference to  FIG. 2  (e.g., electronic device  500  can be the same as electronic device  200 ). 
     Returning to  FIG. 5 , a user U manipulates the orientation and position of stylus  520  relative to surface of the touch-sensitive display input component  510   a  (e.g., a particular input component  510 ) of electronic device  500  in order to convey information to electronic device  500 . Electronic device  500  may be configured to perform or coordinate multiple operations such as, but not limited to, locating stylus  520 , estimating the angular position of stylus  520 , estimating the magnitude of force by stylus  520  to surface of the touch-sensitive display  510   a , determining a variable setting of a variable input component of stylus  520 , determining a variable setting of an application running on electronic device  500  (e.g., a virtual drawing space application), and/or a combination thereof. The electronic device  500  can perform these and other operations at the same time or at different times. In one non-limiting example, the operation of determining the location of stylus  520  can be performed simultaneously with the operation of determining the angular position of stylus  520 , while the operation of estimating the magnitude of force by stylus  520  to surface of the touch-sensitive display  510   a  may be performed periodically and/or based on whether electronic device  500  is configured to accept force input from stylus  520  given a particular operational mode of electronic device  500  (or of stylus  520 ) at a particular time. 
       FIG. 5  illustrates an exemplary stylus  520  and exemplary electronic device  500  according to some examples of the disclosure. A user U can grip a barrel or handle or body portion  522  of stylus  520  extending between a front tip portion  515  of stylus  520  and a rear tip portion  524  of stylus  520 . User U may interact with the electronic device  500  by sliding a tip portion, such as tip portion  515 , of stylus  520  across surface of the touch-sensitive display  510   a  of electronic device  500 . As shown in  FIG. 5 , for example, device  500  can be a tablet computing device. It should be understood that many other electronic devices (with or without displays positioned below a stylus surface of the touch-sensitive display), such as any of the electronic device described above with reference to  FIGS. 1A-1E , can be used to detect stylus  520 . For example, the electronic device can be implemented as a peripheral input device, a trackpad, a drawing tablet, and the like. 
     In some examples, stylus  520  may have a general form of a writing instrument, such as a pen or a pencil-like structure with a cylindrical body  522  with two ends, such as a first end terminated at front portion  515  and a second end terminated at rear portion  524 . One or more of portions  515  and  524  can be removable, affixed to body  522 , or an integral part of body  522 . In some examples, other input devices with different form factors are possible. 
     The stylus  520  can include one or more input or output components, which can be located at one or more of portions  515 - 524  of stylus  520 . These components can include a button, a dial, a slide, a force pad, a touch pad, audio component, haptic component, and the like, may at least partially reside. As one example, at least a portion of a simple mechanical switch or button input component that may be manipulated by user U for adjusting a variable setting of stylus  520  can be located at aperture  516 . In some examples, stylus  520  can operate in a first mode when such an input component is manipulated in a first way and in a second mode when such an input component is manipulated in a second way. 
     Rear portion  524  of stylus  520  may provide a cosmetic end to body  522 . Rear portion  524  may be formed integrally with body  522 . In some examples, rear portion  524  may be formed similarly to front portion  515 . For example, rear portion  524  may provide another tip feature for interacting with a surface of the touch-sensitive display of device  500  (e.g., stylus  520  may be flipped over by user U to drag portion  524  across surface of the touch-sensitive display input component  510   a  of electronic device  500  rather than to drag portion  515  across surface of the touch-sensitive display input component  510   a  of electronic device  500 , which may enable different interactions with device  500 ). In some examples, rear portion  524  may include a switch or button or any other input component that may be manipulated by user U for adjusting a setting of stylus  520 . 
     Tip portion  515  of stylus  520  may be configured to contact or nearly contact surface of the touch-sensitive display  510   a  of device  500 , allowing the user U to use the stylus  520  to interact with the device  500 . In some examples, tip  515  can include a tapered end or point, similar to a pen, which can enable the user U to more precisely control stylus  520  and provide a familiar form factor. In some examples, tip  515  may be blunt or rounded, may take the form of a rotatable or fixed ball, or may have another shape. Tip  515  can include a material that can be softer than a material of the surface of the touch-sensitive display  510   a . For example, tip  515  can include a silicone, a rubber, a fluoro-elastomer, a plastic, a nylon, conductive or dielectric foam, a brass or metal ball with a polymer coating or dielectric coating (e.g., a thin coating with a high dielectric constant) or any other suitable coating, or any other suitable material or combination of materials. In some examples, tip  515  not cause damage to surface of the touch-sensitive display  510   a  or layers applied to surface of the touch-sensitive display  510   a  when the stylus  520  is in use. 
     In some examples, a stylus may not include a power supply (e.g., battery or wired powered supply), therefore, the stylus  520  may not be operative to generate any stylus electric field independently (e.g., without being stimulated by an external stimulus). Instead, a stylus may be provided with limited stylus I/O circuitry that may be operative to be stimulated by an external stimulus, such as a device stimulus that may be generated by device I/O circuitry of device I/O interface  511   a  of electronic device  500  and that may be operative to stimulate the stylus I/O circuitry when located proximate to device I/O interface  511   a  and/or by user U when holding stylus  520 , whereby that stimulation of the stylus I/O circuitry may be operative to enable the stylus I/O circuitry to provide any suitable stylus electric field that may then be detected by device  500  for estimating the location of the stylus. Not only may such stylus I/O circuitry be configured to require no internal power supply for providing a unique stylus electric field, but also such stylus I/O circuitry, when stimulated, may be configured to provide a stylus electric field that may be distinguishable by device  500  from an electric field that may be provided by a user&#39;s direct contact with device I/O interface  511   a.    
     For example,  FIG. 6  illustrates an exemplary stylus  600  according to some examples of the disclosure. In some examples, stylus  600  may include stylus I/O circuitry  611   a . Stylus I/O circuitry  611   a  may operate in response to external stimulus, such as a drive signal generated by an electronic device (e.g., electronic device  136 ,  140 ,  144 ,  148 ,  150 ,  200 , or  500 ). As shown by  FIG. 6 , for example, stylus  600  may include body portion  617   a  extending between a front tip portion  615   a  and a rear tip portion (not shown), where body portion  617   a  may be configured to be held by user U as the user uses stylus  600  to interact with an electronic device. 
     In some examples, stylus I/O circuitry  611   a  can include a front tip interface component  621   a  that can be included in front tip portion  615   a  of the stylus  600 . In some examples, front tip interface component  621   a  can include one or more of, silicone, rubber, fluoro-elastomer, plastic, nylon, conductive or dielectric foam, metal (e.g., brass (e.g., a brass ball with a dielectric or polymer coating (e.g., a thin coating with a high dielectric constant))), or any other suitable material or combination of materials. Thus, in some examples, contact and movement of front tip interface component  621   a  across surface of the touch-sensitive display  510   a  of electronic device  500  may not damage surface of the touch-sensitive display  510   a  or layers applied to surface of the touch-sensitive display  510   a . In some examples, front tip interface component  621   a  can be removably attached to body  617   a , such as via threadings/screws, detents and/or recesses, interference-fit or snap-fit, and/or magnetic attraction, and/or the like. 
     Front tip stylus circuitry  626   a  may be positioned between and electrically coupled to front tip interface component  621   a  and body stylus circuitry  627   a . Front tip stylus circuitry  626   a  can provide a non-linear load between body stylus circuitry  627   a  and front tip interface component  621   a . In some examples, the front tip interface component  621   a  of stylus  600  may be stimulated by a signal that can be generated by device I/O circuitry of device I/O interface  511   a  of electronic device  500 . For example, front tip stylus circuitry  626   a  may include any suitable non-linear electrical circuitry  623   a  that may be electrically coupled (e.g., in series) between front tip interface component  621   a  and body stylus circuitry  627   a . For example, the non-linear circuitry  623   a  of stylus  600  can include at least one diode  622   a . As shown in  FIG. 6 , an anode A of diode  622   a  may be electrically coupled to body stylus circuitry  627   a  and a cathode C of diode  622   a  may be electrically coupled to front tip interface component  621   a . It should be understood, however, that it is possible to orient the diode  622   a  in the opposite way (e.g., connecting the anode A to the front tip interface component  621   a ). In some examples, the stylus  600  can include any suitable number (e.g., one or two or three or four or more) of diodes  622   a . The diodes can be coupled together in series (e.g., a cathode of one diode may be coupled to an anode of a next diode and/or the like) or in parallel. 
     Device I/O circuitry of I/O interface  511   a  of an electronic device  500  may provide a drive signal that can stimulate front tip interface component  621   a  of stylus  600  when front tip interface component  621   a  of stylus  600  is proximate to or touching surface of the touch-sensitive display input component  510   a  of I/O interface  511   a . In some examples, the drive signal can be capacitively coupled to the tip  621   a  of the stylus  600 . A non-linear response of the stylus  600  can be transmitted via tip  621   a  to one or more sense electrodes of the electronic device  500 , enabling the electronic device  500  to detect and locate the stylus  600 . 
     Moreover, in some examples, non-linear electrical circuitry  623   a  that may be electrically coupled to front tip interface component  621   a  may enable stylus  600  to be identified and distinguished from nearby user touches, dragging fingers, palm rests, and/or the like, due to a non-linear load that may generate a non-linear distortion or harmonics (e.g., a second harmonic) at touch pixels near the stylus tip. In some examples, diode  622   a  may be provided with any suitable characteristics that enable the electronic device  500  to detect stylus  600 . For example, diode  622   a  can have a low capacitance (e.g., low parasitic capacitance), low reverse leakage, and/or low turn on voltage diode. The junction capacitance of such a diode may be configured to be low (e.g., less than 1.0 picofarad and/or less than 50 femtofarads). A reverse leakage current of such a diode may be controlled to be not too high. A Schottky diode, two or more Schottky diodes in series, or a specifically designed diode may be used. 
     In some examples, as shown, circuitry  626   a  may also include (e.g., in parallel with non-linear electrical circuitry  623   a ) any suitable resistance circuitry  625   a  (e.g., at least one resistor  624   a ). Resistor  624   a  can control reverse leakage current of non-linear electrical circuitry  623   a  and/or prevent direct current (“DC”) positive voltage build up at the diode by, for example, draining off any DC while maintaining non-linearity of circuitry  626   a . The resistance of resistor  624   a  may be selected in any suitable manner, such as by using a model of the panel, including its stimulation voltage and capacitance to the tip, and the non-linear device model, and optimizing the model. As an example, when using one or more Schottky diodes for non-linear electrical circuitry  623   a , the resistance of resistor  624   a  can be in the range of 4.0-6.0 megohms, or even no additional leakage may be needed. 
     Therefore, stylus  600  may be configured to operate as a passive or semi-passive, non-linear stylus. A semi-passive stylus may be a stylus without an active transmitter, such as a stylus that may be configured to react to the incident field but that may not be a simple linear probe like a user&#39;s finger or a conductive rod. Stylus  600  may be fabricated at a very low cost, as it may not require any internal power supply and may not require any direct coupling or communication of any wired/wireless communication interface with device  500 . Stylus  600  can have an advantage over a passive stylus on a projected capacitance input device by being able to be distinguished from direct user touch events (e.g., unintentional user touch events). Non-linearity of stylus  600  may double (or otherwise provide any suitable multiple of) a modulation frequency (e.g., a fundamental frequency) of a transmitted signal TS (e.g., from 200 kHz to 400 kHz (see, e.g.,  FIG. 7D , from a first harmonic  771  to a second harmonic  773 )) such that many cycles of non-linearity may be detected, such that noise may be reduced by requiring detection of a harmonic multiple times within multiple cycles or just once in a single cycle. 
       FIGS. 7A-7B  illustrate the capacitive coupling  704  of an exemplary stylus  700  to a touch-sensitive surface  702  according to some examples of the disclosure. Stylus  700  can be the same as or similar to stylus  520  or stylus  600 , described above with reference to  FIGS. 5-6 , for example. In some examples, the touch-sensitive surface  702  can be a touch screen or other touch-sensitive surface described above with reference to  FIGS. 1A-5 . 
     As described above with reference to  FIG. 6 , in some examples, a stylus  600  can include conductive components (e.g., the components included in front tip stylus circuitry  626   a ) at a location spaced away from the stylus tip  621   a . In some situations, these components can capacitively couple to touch-sensitive surface  702 . 
     Referring to  FIG. 7A , while the stylus  700  is normal or substantially normal to the touch-sensitive surface  702 , the capacitive coupling  704  of portions of the stylus away from the stylus tip  710  (e.g., capacitive coupling of the front tip stylus circuitry  626   a ) can be equal or substantially equal on all sides of the stylus  700 . Thus, the centroid of the stylus  700  as detected by the touch sensitive surface  702  can be the location on the touch-sensitive surface at which the stylus tip  710  is located on the touch-sensitive surface. 
     Referring to  FIG. 7B , while the stylus  700  is positioned at an angle relative to a position that is normal or substantially normal to the touch-sensitive surface  702 , the capacitive coupling  704  of portions of the stylus away from the stylus tip  710  (e.g., capacitive coupling of the front tip stylus circuitry  626   a ) can be greater on a side of the stylus  700  that is closer to the touch-sensitive surface  702  than the other sides of the stylus. Thus, the centroid of the stylus  700  as detected by the touch sensitive surface  702  can be a location on the touch-sensitive surface different from the location at which the stylus tip  710  is located on the touch sensitive-surface. 
       FIG. 7C  illustrates an exemplary true position  708  and an exemplary detected position  706  of a stylus  700  that is not normal or substantially normal to the touch-sensitive surface  702  according to some examples of the disclosure. For example, the angle of the stylus  700  in  FIG. 7C  can be the same as or similar to the angle of the stylus in  FIG. 7B . As shown in  FIG. 7C , the detected position  706  of the stylus  700  (e.g., the position detected by an electronic device in communication with touch sensitive surface  702 ) can be different from the true position  708  of the tip of the stylus  700 . For example, the detected position  706  of the stylus  700  can be towards the portion of the stylus that is tilted towards the touch-sensitive surface  702  due to the capacitive coupling between the touch-sensitive surface  702  and one or more conductive components included in the stylus  700  (e.g., front tip stylus circuitry  626   a ). 
     Therefore, in some examples, it can be advantageous to prevent or reduce capacitive coupling of components of the stylus other than the stylus tip  710  to the touch-sensitive surface  702 . In some examples, a stylus can include a conductive element disposed around at least some of the stylus circuitry that can prevent capacitive coupling of the circuitry to a touch-sensitive surface at which the stylus is being used to provide an input. In some examples, the closer the conductive element is placed to the tip  710  of the stylus, the more components of the circuitry the conductive element is able to shield. Thus, in some examples, placing the conductive element close to the stylus tip  710  can be advantageous because such placement can have improved shielding properties. In some examples, however, placing the conductive component too close to the stylus tip  710  can cause the stylus tip to capacitively couple to the conductive component, thereby causing a reduction in the strength of the signal being provided by the stylus tip  710 . Thus, in some examples, placing the conductive element further away from the stylus tip  710  can be advantageous because such placement can improve signal strength of the stylus tip. In some examples, the tradeoff between improved shielding and improved stylus tip signal strength can be made to determine appropriate placement of the conductive element. In some examples, the conductive element can be placed 2 mm-20 mm from the tip  710  of the stylus  700 .  FIGS. 8A-110  illustrate examples of styluses that include conductive elements that can reduce the amount of capacitive coupling of one or more components of the stylus to the touch-sensitive surface. 
       FIG. 8A  illustrates an exemplary stylus  800  that includes a printed circuit board (PCB)  804  having shielding traces  806  according to some examples of the disclosure.  FIG. 8A  illustrates a cross-section along a length of stylus  800  that includes a housing  810  in which tip electrode  802  and PCB  804  can be disposed. In some examples, the PCB  804  can include the front tip stylus circuitry  626   a  (not shown in  FIG. 8A ), an electrode  808  that can be coupled to a reference voltage, and shielding traces  806 . In some examples, the electrode  808  can be coupled to the outside of the housing  810  of stylus  800 . Thus, for example, the electrode  808  can be at a same electric potential as the user holding stylus  800 . In some examples, if the user is coupled to earth ground or another reference voltage, the electrode  808  can be a connection to earth ground or another reference voltage. In some examples, shielding traces  806  can be coupled to electrode  808  or can be at a floating electric potential (e.g., not coupled to a reference voltage or voltage source). Shielding traces  806  can include a conductive material (e.g., a metal such as copper, silver, gold, etc.). In some examples, shielding traces  806  can capacitively couple to the front tip stylus circuitry  626   a  and/or other components of PCB  804  and/or to the touch sensitive surface, which can prevent the front tip stylus circuitry  626   a  and/or other components of PCB  804  from capacitively coupling to the touch-sensitive surface that is detecting the location of the stylus tip electrode  802 . 
       FIG. 8B  illustrates an exemplary PCB  804  including shield traces  806  according to some examples of the disclosure. PCB  804  illustrated in  FIG. 8B  can be the same as the PCB  804  included in  FIG. 8A  illustrated from a different angle (e.g., an angle in the plane of the surface of the Figures). As shown in  FIG. 8B , the shielding traces  806  of the PCB can wrap from a first side of the PCB  804  (e.g., a side illustrated in  FIG. 8A ), around an edge of the PCB (e.g., the edge illustrated in  FIG. 8B ), to an opposite side of the PCB (e.g., a side opposite from the side illustrated in  FIG. 8A ). Although  FIG. 8B  illustrates one of the two shielding traces  806  illustrated in  FIG. 8A , it should be understood that both of the shielding traces  806  of  FIG. 8A  can wrap around the edges of the PCB  804  in the manner illustrated in  FIG. 8B  and as described herein. 
       FIG. 9A  illustrates an exemplary stylus  900  that includes a PCB  904  having a shield can  906  according to some examples of the disclosure.  FIG. 9A  illustrates a cross-section along a length of stylus  900  that includes a housing  910  in which tip electrode  902  and PCB  904  can be disposed. In some examples, the PCB  904  can include the front tip stylus circuitry  626   a  (not shown in  FIG. 9A ), an electrode  908  that can be coupled to a reference voltage, and shield can  906 . In some examples, electrode  908  can be similar to electrode  808  described above with reference to  FIG. 8A . In some examples, shield can  906  can be coupled to electrode  908  or can be at a floating electric potential (e.g., not coupled to a reference voltage or voltage source). Shield can  906  can include a conductive material (e.g., a metal such as copper, silver, gold, etc.). Shield can  906  can be disposed around the components of PCB  904  such that shield can  906  is disposed between the components of PCB  904  and the housing  910  of stylus  900 , for example. Thus, in some examples, the shield can  906  can be positioned between the components of PCB  904  and the touch-sensitive surface while the stylus  900  is being used to provide an input to the touch-sensitive surface. In some examples, shield can  906  can capacitively couple to the front tip stylus circuitry  626   a  and/or other components of PCB  904  and/or to the touch sensitive surface, which can prevent the front tip stylus circuitry  626   a  and/or other components of PCB  904  from capacitively coupling to the touch-sensitive surface that is detecting the location of the stylus tip electrode  902 . 
       FIG. 9B  illustrates an exemplary PCB  904  including shield can  906  according to some examples of the disclosure. PCB  904  illustrated in  FIG. 9B  can be the same as the PCB  904  included in  FIG. 9A  illustrated from a different angle (e.g., an angle in the plane of the surface of the Figures). As shown in  FIG. 9B , the shield can  906  of the PCB  904  can cover the components of the PCB, thus providing a shield between the components of PCB and the touch-sensitive surface while the stylus  900  is being used to provide an input to a touch-sensitive surface. Although  FIG. 9B  illustrates one of the two shield cans  906  illustrated in  FIG. 9A , it should be understood that both of the shield cans  906  of  FIG. 9A  can cover components of the PCB  904  in the manner illustrated in  FIG. 9B  and as described herein. 
       FIG. 10  illustrates an exemplary stylus  1000  that includes a conductive sleeve  1006  according to some examples of the disclosure.  FIG. 10  illustrates a cross-section along a length of stylus  1000  that includes a housing  1010  in which tip electrode  1002 , PCB  1004 , and conductive sleeve  1006  can be disposed. In some examples, the PCB  1004  can include the front tip stylus circuitry  626   a  (not shown in  FIG. 10 ). Conductive sleeve  1006  can include a hollow cylindrical portion disposed around the PCB  1004  and a solid portion that can function similarly to electrode  808  and electrode  908 , described above with reference to  FIGS. 8A-9B , for example. In some examples, the conductive sleeve  1006  can be electrically coupled to the PCB  1004  to provide a reference voltage to PCB  1004 . In some examples, conductive sleeve  1006  can be at a floating electric potential (e.g., not coupled to a reference voltage or voltage source) and/or can be electrically coupled to the user while the user holds stylus  1000  (e.g., through a conductive portion of the exterior of the housing  1010 ). In some examples, coupling the conductive sleeve  1006  to the user while the user holds the stylus  1000  can provide a connection to ground if the user is well-grounded. 
     Conductive sleeve  1006  can include a conductive material (e.g., a metal such as copper, silver, gold, etc.), for example. Conductive sleeve  1006  can be disposed around the components of PCB  1004  such that conductive sleeve  1006  is disposed between the components of PCB  1004  and the housing  1010  of stylus  1000 , for example. Thus, in some examples, the conductive sleeve  1006  can be positioned between the components of PCB  1004  and the touch-sensitive surface while the stylus  1000  is being used to provide an input to the touch-sensitive surface. In some examples, the conductive sleeve  1006  can capacitively couple to the front tip stylus circuitry  626   a  and/or other components of PCB  1004  and/or to the touch sensitive surface, which can prevent the front tip stylus circuitry  626   a  and/or other components of PCB  1004  from capacitively coupling to the touch-sensitive surface that is detecting the location of the stylus tip electrode  1002 . 
     In some examples, the conductive sleeve  1006  be formed from metal (e.g., copper, silver, gold, etc.). For example, a solid metal rod can be formed and, subsequently, a cavity can be cut into the rod into which the PCB  1004  can be disposed when the conductive sleeve  1006  and PCB  1004  are assembled in the stylus. In some examples, the stylus housing  1010  can be formed from plastic that can be injection molded around the conductive sleeve  1006 . In some examples, the conductive sleeve  1006  can be formed from plastic including embedded metal particles. For example, the conductive sleeve  1006  and/or stylus housing  1010  can be injection molded from a material including metal particles and plastic. In some examples, the conductive sleeve  1006  can be integrated with the housing  1010  of the stylus  1000  in this way (e.g., the stylus housing can be formed from a conductive material instead of incorporating a separate conductive sleeve  1006 ). 
       FIGS. 11A-110  illustrate an exemplary stylus  1100  that includes a conductive sleeve  1106  according to some examples of the disclosure.  FIG. 11A  illustrates a cross-section along a length of stylus  1100  that includes a housing  1110  in which tip electrode  1102 , PCB  1104 , and conductive sleeve  1106  can be disposed. In some examples, the PCB  1104  can include the front tip stylus circuitry  626   a  (not shown in  FIG. 11 ) and electrode  1108  that can be coupled to a reference voltage. In some examples, electrode  1108  can be similar to electrode  808  described above with reference to  FIG. 8A  and/or electrode  908  described above with reference to  FIGS. 9A-8B . Conductive sleeve  1106  can be disposed around the PCB  1104 . In some examples, the conductive sleeve  1106  can be electrically coupled to electrode  1108 . In some examples, conductive sleeve  1106  or can be at a floating electric potential (e.g., not coupled to a reference voltage, voltage source, or electrode  1108 ) and/or can be electrically coupled to the user while the user holds stylus  1100  (e.g., through a conductive portion of the exterior of the housing  1110 ). In some examples, coupling the conductive sleeve  1106  to the user while the user holds the stylus  1100  can provide a connection to ground if the user is well-grounded. Conductive sleeve  1106  can include a conductive material (e.g., a metal such as copper, silver, gold, etc.), for example. Conductive sleeve  1106  can be disposed around the components of PCB  1104  such that conductive sleeve  1106  is disposed between the components of PCB  1104  and the housing  1110  of stylus  1100 , for example. In some embodiments, however, the conductive sleeve  1106  can be integrated with the housing  1110  of the stylus  1100  or can be disposed around housing  1110 . Thus, in some examples, the conductive sleeve  1106  can be positioned between the components of PCB  1104  and the touch-sensitive surface while the stylus  1100  is being used to provide an input to the touch-sensitive surface. In some examples, the conductive sleeve  1106  can capacitively couple to the front tip stylus circuitry  626   a  and/or other components of PCB  1104  and/or to the touch sensitive surface, which can prevent the front tip stylus circuitry  626   a  and/or other components of PCB  1004  from capacitively coupling to the touch-sensitive surface that is detecting the location of the stylus tip electrode  1102 . 
       FIG. 11B  illustrates an exemplary conductive sleeve  1106  according to some examples of the disclosure. In some examples, conductive sleeve can be included in stylus  1100  illustrated in  FIG. 11A  or incorporated into one of the examples described below with reference to  FIGS. 11C-11O . As shown in  FIG. 11B , in some examples, the conductive sleeve  1106  can have a hollow cylinder shape. In some examples, other shapes are possible. The conductive sleeve  1106  can include a conductive material (e.g., copper, gold, silver, etc.). 
     In some examples, a stylus can include a conductive sleeve that is integrated with the PCB of the stylus, such as in  FIGS. 11C-11D .  FIG. 11C  illustrates an exemplary stylus  1100 A that includes a conductive sleeve  1106 A that can be integrated with PCB  1104 A according to some examples of the disclosure.  FIG. 11C  illustrates a cross-section of the stylus  1100 A at a respective location along the length of the stylus  1100 A that includes the PCB  1104 A. Although  FIG. 11C  does not illustrate a stylus tip electrode  1102  or additional electrode  1108  (e.g., as shown in  FIG. 11A ), it should be understood that, in some examples, stylus  1100 A can include these and other components. 
     As shown in  FIG. 11C , conductive sleeve  1106 A can be attached to PCB  1104 A and disposed between the components  1112  of PCB  1104 A and the housing  1110 A of stylus  1100 A, for example. In some examples, components  1112  of PCB  1104 A can include the front tip stylus circuitry  626   a  described above with reference to  FIG. 6 . In some examples, the conductive sleeve  1106 A can include a conductive material (e.g., copper, silver, gold). While the stylus  1100 A is in use with a touch-sensitive surface, the conductive sleeve  1106 A can be disposed between the PCB  1104 A and the touch-sensitive surface, which can prevent capacitive coupling of the components  1112  of PCB  1104 A and the touch-sensitive surface, for example. In some examples, the components  1112  of PCB  1104 A and/or the touch sensitive surface can capacitively couple to the conductive sleeve  1106 A instead of the components  1112  of PCB  1104 A and the touch-sensitive surface capacitively coupling together. In some examples, the tension of the conductive sleeve  1106 A can hold the PCB  1104 A in place inside of the stylus body  1110 A. In some examples, the inside of the stylus body  1110 A can include brackets or other fasteners that can couple to the conductive sleeve  1106 A and/or the PCB  1104 A to hold the PCB  1104 A in place inside the body  1110 A of the stylus  1100 A. 
       FIG. 11D  illustrates an exemplary PCB  1104 A including a conductive sleeve  1106 A according to some examples of the disclosure.  FIG. 11D  illustrates the PCB  1104 A while it is not disposed inside a stylus (e.g., stylus  1100 A illustrated in  FIG. 11C ) while the conductive sleeve  1106 A is unrolled. In some examples, the conductive sleeve  1106 A can be coupled to one of the edges of the PCB  1104 A. The PCB  1104 A can include a plurality of components  1112  (e.g., including front tip stylus circuitry  626   a  described above with reference to  FIG. 6 ), for example.  FIG. 11D  illustrates one side of the PCB  1104 A. It should be understood that, in some examples, PCB  1104 A can include additional components on the side opposite to the side of the PCB  1104 A illustrated in  FIG. 11D . In some examples, the components  1112  are disposed in a first region of the PCB  1104 A (e.g., a region that remains flat while the PCB  1104 A is disposed within stylus  1100 A) that is different from the conductive sleeve  1106 A (e.g., there are no components disposed on the surface of conductive sleeve  1106 A). 
       FIG. 11E  illustrates an exemplary stylus  1100 B including a conductive sleeve  1106 B with spring clips  1111   a ,  1111   b , and/or  1111   c  according to some examples of the disclosure.  FIG. 11E  illustrates a cross-section of the stylus  1100 B at a respective location along the length of the stylus  1100 B that includes the PCB  1104 B. Although  FIG. 11E  does not illustrate a stylus tip electrode  1102  or additional electrode  1108  (e.g., as shown in  FIG. 11A ), it should be understood that, in some examples, stylus  1100 B can include these and other components. 
     As shown in  FIG. 11E , conductive sleeve  1106 B can be disposed within the housing  1110 B of the stylus  1100 B. In some examples, the conductive sleeve  1106 B can include spring clips  1111   a ,  1111   b , and/or  1111   c  that can be attached to PCB  1104 B. Spring clips  1111   a ,  1111   b , and/or  1111   c  can represent different possible cross-sections of conductive sleeve  1106 B. For example, conductive sleeve  1106 B can include spring clips  1111   b  or  1111   c . In some examples, if conductive sleeve  1106 B includes spring clips  1111   a , the width of PCB  1104 B can be modified to reach spring clips  1111   a . In some examples, two or more profiles of spring clips  1111   a ,  1111   b , and  1111   c  can be combined. In some examples, spring clips  1111   a - c  and the rest of conductive sleeve  1106 B can be a single integrated component. For example, conductive sleeve  1106 B and spring clips  1111   a - c  can be formed from a single piece of spring sheet metal. In some examples, spring clips  1111   a - c  can be a separate component that is coupled to conductive sleeve  1106 B (e.g., with an adhesive, via welding, via fasteners, etc.). The spring clips  1111   a - c  may be conductive or non-conductive, for example. 
     Thus, the PCB  1104 B can be held in place inside of stylus  1100 B by the conductive sleeve  1106 B, for example. In some examples, a spring force of conductive sleeve  1106 B can hold the conductive sleeve  1106 B in place inside stylus  1100 B. In some examples, the conductive sleeve  1106 B can be disposed between the components  1112  of PCB  1104 B and the housing  1110 B of stylus  1100 B, for example. In some examples, components  1112  of PCB  1104 B can include the front tip stylus circuitry  626   a  described above with reference to  FIG. 6 . In some examples, the conductive sleeve  1106 B can include a conductive material (e.g., spring sheet metal, sheet metal, steel, copper, silver, gold). While the stylus  1100 B is in use with a touch-sensitive surface, the conductive sleeve  1106 B can be disposed between the PCB  1104 B and the touch-sensitive surface, which can prevent capacitive coupling of the components  1112  of PCB  1104 B and the touch-sensitive surface, for example. In some examples, the components  1112  of PCB  1104 B and/or the touch sensitive surface can capacitively couple to the conductive sleeve  1106 B instead of the components  1112  of PCB  1104 B and the touch-sensitive surface capacitively coupling together. 
     In some examples, a stylus can include a PCB with conductive springs that act as conductive shielding components that can be disposed at a shaft of the stylus, such as in  FIGS. 11F-11G .  FIG. 11F  illustrates an exemplary stylus  1100 C that includes conductive springs  1106 C- 1  and  1106 C- 2  coupled to the PCB  1104 C of the stylus  1100 C according to some examples of the disclosure.  FIG. 11F  illustrates a cross-section of the stylus  1100 C at a respective location along the length of the stylus  1100 C that includes the PCB  1104 C. In some examples, the PCB  1104 C and the conductive springs  1106 C can be disposed at a location along the shaft of the stylus  1100 C at which the stylus is cylindrical (e.g., as opposed to being cone-shaped, such as towards the tip of the stylus). Although  FIG. 11F  does not illustrate a stylus tip electrode  1102  or additional electrode  1108  (e.g., as shown in  FIG. 11A ), it should be understood that, in some examples, stylus  1100 C can include these and other components. 
     As shown in  FIG. 11F , conductive springs  1106 C- 1  and  1106 C- 2  can be disposed within the housing  1110 C of the stylus  1100 C. In some examples, the conductive springs  1106 C can be attached to PCB  1104 C, as will be described in more detail below with reference to  FIG. 11G . Thus, the PCB  1104 C can be held in place inside of stylus  1100 C by the conductive springs  1106 C, for example. In some examples, the conductive springs  1106 C can be disposed between the components  1112  of PCB  1104 C and the housing  1110 C of stylus  1100 C, for example. In some examples, components  1112  of PCB  1104 C can include the front tip stylus circuitry  626   a  described above with reference to  FIG. 6 . In some examples, the conductive springs  1106 C can include a conductive material (e.g., copper, silver, gold). While the stylus  1100 C is in use with a touch-sensitive surface, the conductive springs  1106 C can be disposed between the PCB  1104 C and the touch-sensitive surface, which can prevent capacitive coupling of the components  1112  of PCB  1104 C and the touch-sensitive surface, for example. In some examples, the components  1112  of PCB  1104 C and/or the touch sensitive surface can capacitively couple to the conductive springs  1106 C instead of the components  1112  of PCB  1104 C and the touch-sensitive surface capacitively coupling together. 
       FIG. 11G  illustrates an exemplary PCB  1104 C that includes conductive springs  1106 C- 1  and  1106 C- 2  according to some examples of the disclosure.  FIG. 11G  illustrates the PCB  1104 C and conductive springs  1106 C described above with reference to  FIG. 11F . In  FIG. 11G , the PCB  1104 C and conductive springs  1106 C are disposed outside of the stylus  1100 C and the conductive springs are uncurled. In some examples, while the PCB  1104 C and conductive springs  1106 C are disposed within stylus  1100 C, such as in  FIG. 11F , the spring force of the conductive springs (e.g., the force attempting to uncurl the conductive springs) can hold the PCB  1104 C and the conductive springs  1106 C in place inside stylus  1100 C. In some examples, the PCB  1104 C can include two conductive springs  1106 C- 1  and  1106 C- 2  attached along opposite edges and on opposite sides of the PCB  1104 C. For example, conductive spring  1106 C- 1  can be attached along an edge of the PCB  1104 C that is along the top of the PCB in the orientation shown in  FIG. 11G  on the side of the PCB  1104 C illustrated in  FIG. 11G . Likewise, for example, conductive spring  1106 C- 2  can be attached along an edge of the PCB  1104 C that is along the bottom of the PCB in the orientation shown in  FIG. 11G  on the side opposite from the side of the PCB  1104 C illustrated in  FIG. 11G . In some examples, the PCB  1104 C can further include components  1112  (e.g., front tip stylus circuitry  626   a  illustrated in  FIG. 6 ) disposed on the side of PCB  1104 C illustrated in  FIG. 11G  and on opposite side of the PCB (not shown). 
     As shown in  FIG. 11G , each conductive spring  1106 C- 1  and  1106 C- 2  can include optional cuts or slits  1107 A in a direction extending from the PCB  1104 C and away from the PCB (e.g., across the width of the conductive springs). In some examples, the cuts or slits  1107 A are omitted and the conductive springs  1106 C- 1  and  1106 C- 2  can be formed from solid pieces of conductive material. In some examples, the cuts or slits  1107  can reduce the stiffness of the conductive springs  1106 C, making the springs easier to roll prior to insertion into the stylus  1100 C. 
     In some examples, a stylus can include a PCB with conductive springs that can act as conductive shield components disposed at least partially in the tip of the stylus, such as in  FIGS. 11H-11J .  FIG. 11H  illustrates an exemplary stylus  1100 D that includes conductive springs  1106 D- 1  and  1106 D- 2  coupled to the PCB  1104 D of the stylus  1100 D according to some examples of the disclosure.  FIG. 11H  illustrates a cross-section of the stylus  1100 D at a respective location along the length of the stylus  1100 D that includes the PCB  1104 D. In some examples, the PCB  1104 D and the conductive springs  1106 D can be disposed at a location in the tip of the stylus at which the stylus is cone-shaped (e.g., as opposed to being cylindrical, such as along the shaft of the stylus). Although  FIG. 11H  does not illustrate an additional electrode  1108  (e.g., as shown in  FIG. 11A ), it should be understood that, in some examples, stylus  1100 H can include these and other components. 
       FIG. 11I  illustrates an exemplary stylus  1100 D that includes conductive springs  1106 D- 1  and  1106 D- 2  coupled to the PCB  1104 D of the stylus  1100 D according to some examples of the disclosure.  FIG. 11I  illustrates a cross-section of the stylus  1100 D at a respective location along the length of the stylus  1100 D that includes the PCB  1104 D. For example, the stylus  1100 D illustrated in  FIG. 11I  is the same stylus illustrated in  FIG. 11H . In some examples, the PCB  1104 D and the conductive springs  1106 D can be disposed at a location in the tip of the stylus  1100 D at which the stylus is cone-shaped (e.g., as opposed to being cylindrical, such as along the shaft of the stylus). Although  FIG. 11I  does not illustrate a stylus tip electrode  1102  or additional electrode  1108  (e.g., as shown in  FIG. 11A ), it should be understood that, in some examples, stylus  1100 D can include these and other components. 
     As shown in  FIGS. 11H-11I , conductive springs  1106 D- 1  and  1106 D- 2  can be disposed within the housing  1110 D of the stylus  1100 D and follow the curve of the housing of the stylus. In some examples, the conductive springs  1106 D can be attached to PCB  1104 D, as shown in  FIG. 11I  and described in more detail below with reference to  FIG. 11J . Thus, the PCB  1104 D can be held in place inside of stylus  1100 D by the conductive springs  1106 D, for example. For example, the spring force of the conductive springs  1106 D attempting to uncurl can secure the conductive springs and the PCB  1104 D inside stylus  1100 D. In some examples, the conductive springs  1106 D can be disposed between the components  1112  of PCB  1104 D and the housing  1110 D of stylus  1100 D, for example. In some examples, components  1112  of PCB  1104 D can include the front tip stylus circuitry  626   a  described above with reference to  FIG. 6 . In some examples, the conductive springs  1106 D can include a conductive material (e.g., copper, silver, gold). While the stylus  1100 D is in use with a touch-sensitive surface, the conductive springs  1106 D can be disposed between the PCB  1104 D and the touch-sensitive surface, which can prevent capacitive coupling of the components  1112  of PCB  1104 D and the touch-sensitive surface, for example. In some examples, the components  1112  of PCB  1104 D and/or the touch sensitive surface can capacitively couple to the conductive springs  1106 D instead of the components  1112  of PCB  1104 D and the touch-sensitive surface capacitively coupling together. 
       FIG. 11J  illustrates an exemplary PCB  1104 D that includes conductive springs  1106 D- 1  and  1106 D- 2  according to some examples of the disclosure.  FIG. 11J  illustrates the PCB  1104 D and conductive springs  1106 D that can be incorporated into stylus  1100 D as described above with reference to  FIGS. 11H-11I . In  FIG. 11J , the PCB  1104 D and conductive springs  1106 D are disposed outside of the stylus  1100 D and the conductive springs are uncurled. In some examples, while the PCB  1104 D and conductive springs  1106 D are disposed within stylus  1100 D, such as in  FIGS. 11H-11I , the spring force of the conductive springs (e.g., the force attempting to uncurl the conductive springs) can hold the PCB  1104 D and the conductive springs  1106 D in place inside stylus  1100 D. The conductive springs  1106 D can have tapered edges: the width of the conductive springs can be narrower at one end of the PCB  1104 D than the other end of the PCB, for example. In some examples, while the PCB  1104 D is disposed within the stylus, such as in  FIGS. 11H-11I , the narrower ends of the conductive springs can be disposed towards the stylus tip electrode  1102  and the wider ends of the conductive springs can be disposed towards the shaft of the stylus  1100 D. 
     In some examples, the PCB  1104 D can include two conductive springs  1106 D- 1  and  1106 D- 2  attached along opposite edges and on opposite sides of the PCB  1104 D. For example, conductive spring  1106 D- 1  can be attached along an edge of the PCB  1104 D that is along the top of the PCB in the orientation shown in  FIG. 11J  on the side of the PCB  1104 D illustrated in  FIG. 11J . Likewise, for example, conductive spring  1106 D- 2  can be attached along an edge of the PCB  1104 D that is along the bottom of the PCB in the orientation shown in  FIG. 11J  on the side opposite from the side of the PCB  1104 D illustrated in  FIG. 11H . In some examples, the PCB  1104 D can further include components  1112  (e.g., front tip stylus circuitry  626   a  illustrated in  FIG. 6 ) disposed on the side of PCB  1104 D illustrated in  FIG. 11J  and on opposite side of the PCB (not shown). 
     As shown in  FIG. 11J , each conductive spring  1106 D- 1  and  1106 D- 2  can include optional cuts or slits  1107 B in a direction extending from the PCB  1104 D and away from the PCB (e.g., across the width of the conductive springs). In some examples, the cuts or slits  1107 B are omitted and the conductive springs  1106 D- 1  and  1106 D- 2  can be formed from solid pieces of conductive material. In some examples, the cuts or slits  1107  can reduce the stiffness of the conductive springs  1106 D, making the springs easier to roll prior to insertion into the stylus  1100 D. 
     In some examples, a stylus can include a conductive shield disposed on the outside of at least a portion of the stylus housing, such as in  FIGS. 11K-11N .  FIGS. 11K-11L  illustrate a portion of a stylus housing  1110 F that includes a conductive shield  1106  disposed on the exterior of the portion of the stylus housing. In some examples, at a later stage in the manufacturing process, an additional portion of the stylus housing can be applied to the exterior of the portion of the stylus housing  1110 F and the conductive shield  1106 . For example, a stylus tip cover can be applied to cover the stylus tip electrode  1102 , as will be described in more detail below with reference to  FIGS. 11M-11N . Thus, in some examples, the stylus can include a conductive shield  1106  embedded in the stylus housing. 
     In some examples, the conductive shield  1106 F can be formed from a conductive material, such as metal (e.g., copper, gold, silver, etc.). In some examples, the conductive material is applied as a foil. The conductive shield  1106 F can include a portion that wraps all the way around the portion of the stylus housing  1110 F and one or more portions that extend along the length of the portion of the stylus housing When the stylus is fully assembled, in some examples, a PCB of the stylus (e.g., including circuitry such as front tip stylus circuitry  626   a ) can be disposed at a location along the length of the stylus that corresponds to the location of the conductive shield  1106 F. In this way, the conductive shield  1106 F can be located between the stylus PCB and the touch-sensitive surface to prevent or reduce capacitive coupling between the stylus PCB and the touch-sensitive surface, as described above with reference to  FIGS. 7-11J . 
       FIGS. 11M-11N  illustrate a portion of the stylus described above with reference to  FIGS. 11K-11L  with stylus tip cover  1114  added to the stylus. In some examples, the stylus tip cover  1114  can be formed from plastic and can be over-molded over the portion of the stylus housing  1110 F and the conductive shield  1106 F. In this way, the conductive shield  1106 F can be disposed between the stylus tip cover  1114  and the portion of the stylus housing  1110 F. In some examples, the stylus can further include a cosmetic cover disposed over the rest of the portion of the stylus housing  1110 F and the portions of the conductive shield  1106 F not covered by the stylus tip cover  1114 . 
     In some examples, a stylus can include a conductive shield disposed between portions of the stylus housing.  FIG. 11O  illustrates an exemplary stylus  1100 G that includes a conductive shield  1106 G disposed between portions  1116  and  1118  of the stylus housing according to some examples of the disclosure. Stylus  1100 G can further include PCB  1104  with components  1112  (e.g., front tip stylus circuitry  626   a ) and stylus tip  1102 , for example. The conductive shield  1106 G can be disposed on the outside of a portion  1116  of the stylus housing that can hold the PCB  1104  and can connect to the stylus front tip electrode  1102 . In some examples, the conductive shield can be formed from a metallic paint that can be applied to the outer surface of the portion  1116  of the stylus housing. The stylus  1100 G can further include another portion  1118  of stylus housing disposed outside of the first portion  1116  of the stylus housing and the conductive shield  1106 G. 
     In some examples, the conductive shield  1106 G can be coupled to a reference electrode of the stylus  1100 G (e.g., similar to electrode  1108 ). While the stylus  1100 G is being used to provide an input via a touch-sensitive surface, the conductive shield  1106 G can be between the PCB  1104  and the touch-sensitive surface to prevent or reduce capacitive coupling between the PCB  1104  and the touch-sensitive surface. 
     Some examples of the disclosure are directed to an input device comprising: a housing oriented along an axis; a printed circuit board (PCB) including circuitry, the circuitry disposed within a first distance of the axis; an electrode coupled to the circuitry; and a conductive element disposed around at least a portion of the circuitry. Additionally or alternatively, in some examples, the conductive element includes a conductive sleeve coupled to a side of the PCB that is parallel to the axis. Additionally or alternatively, in some examples, the conductive element includes a hollow cylinder in which at least the portion of the circuitry is disposed, the conductive element further comprising a plurality of spring clips mechanically coupled to the PCB. Additionally or alternatively, in some examples, the housing includes: a first portion disposed a third distance from the axis, the third distance between the first distance and the second distance, and a second portion disposed a fourth distance from the axis, the fourth distance greater than the third distance, and the conductive element is disposed between the first and second portions of the housing. Additionally or alternatively, in some examples, the conductive element is integrated with the housing. Additionally or alternatively, in some examples, the circuitry includes a second portion located along the axis between the electrode and the conductive element. 
     Some examples of the disclosure are directed to an input device comprising a housing oriented along an axis; a printed circuit board (PCB) including circuitry, the circuitry disposed within a first distance of the axis; an electrode coupled to the circuitry; and a conductive element disposed at a same location along the axis at which at least a portion of the circuitry is disposed, the conductive element being disposed a second distance from the axis that is greater than the first distance. Additionally or alternatively, in some examples, the conductive element includes a conductive trace disposed at the edge of the PCB. Additionally or alternatively, in some examples, the conductive element includes a shield can coupled to the PCB. Additionally or alternatively, in some examples, the conductive element includes: a hollow cylindrical portion in which the PCB is disposed, and a solid portion disposed at a location along the axis different from the same location along the axis at which at least the portion of the circuitry is disposed. Additionally or alternatively, in some examples, the conductive element includes a conductive sleeve coupled to a side of the PCB that is parallel to the axis. Additionally or alternatively, in some examples, the conductive element includes a hollow cylinder in which at least the portion of the circuitry is disposed, the conductive element further comprising a plurality of spring clips mechanically coupled to the PCB. Additionally or alternatively, in some examples, the housing includes: a first portion disposed a third distance from the axis, the third distance between the first distance and the second distance, and a second portion disposed a fourth distance from the axis, the fourth distance greater than the third distance, and the conductive element is disposed between the first and second portions of the housing. Additionally or alternatively, in some examples, the conductive element is integrated with the housing. Additionally or alternatively, in some examples, the circuitry includes a second portion located along the axis between the electrode and the conductive element. 
     Some examples of the disclosure are directed to an input device, comprising: a housing oriented along an axis; a printed circuit board (PCB) including circuitry; an electrode coupled to the circuitry; and a conductive sleeve coupled to a side of the PCB and disposed around at least a portion of the circuitry. Additionally or alternatively, in some examples, the conductive sleeve includes a plurality of slits perpendicular to the axis. Additionally or alternatively, in some examples, the conductive sleeve is parallel to the axis. Additionally or alternatively, in some examples, the conductive sleeve is not parallel to the axis. 
     Although the disclosed examples 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 the disclosed examples as defined by the appended claims.

Metadata:
Filing Date: 20200924
Publication Date: 20221004
Grant Date: 20221004
Priority Date: 20200924
Inventors: BECHSTEIN, DANIEL JACOB BENJAMIN
SMITH, JOHN STEPHEN
SHEKAR, Siddharth
SONGATIKAMAS, TEERA
KIBITI, ELVIS MWENDA
BRAUNER, JARED A.
CORBET, LINDSAY DIANE REGO
CHEUNG, WANG CHUNG ALSTON
AYANOOR-VITIKKATE, VIPIN
SITARAMAN, NITIN
SANCTIS, JOYAN GRATIAN
MARSHALL, BLAKE R.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F2203/04107", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0383", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F2203/04107", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0383", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 80740435