PATENT DOCUMENT

Publication Number: US-9201547-B2
Application Number: US-201213460620-A
Country: US
Kind Code: B2

Title: Wide dynamic range capacitive sensing

Abstract:
A touch sensor panel configured to detect objects touching the panel as well as objects that are at a varying proximity to the touch sensor panel. The touch sensor panel includes circuitry that can configure the panel in a mutual capacitance (near field) architecture or a self-capacitance (far field and super far field) architecture. The touch sensor panel can also include circuitry that works to minimize an effect that a parasitic capacitance can have on the ability of the touch sensor panel to reliably detect touch and proximity events.

Claims:
What is claimed is:  
     
       1. A method of sensing proximity events, comprising:
 configuring a touch sensor panel to a self-capacitance architecture; 
 stimulating the touch sensor panel with one or more stimulation signals to generate one or more touch signals; 
 reducing an effect of a parasitic capacitance on the one or more touch signals received from the touch sensor panel by driving a shield with a shield signal of a same frequency and phase as the one or more stimulation signals, wherein the shield is a physical layer separate from other conductive structures in the touch sensor panel; and 
 determining if a proximity event has occurred based on the one or more reduced parasitic capacitance effect touch signals. 
 
     
     
       2. The method of  claim 1 , wherein reducing the effect of the parasitic capacitance includes offsetting the effect of the parasitic capacitance on a phase of the one or more touch signals. 
     
     
       3. The method of  claim 1 , wherein reducing the effect of parasitic capacitance includes attenuating an amount of parasitic capacitance in the touch sensor panel. 
     
     
       4. The method of  claim 3 , further comprising placing the shield in proximity to one or more touch sensor panel components and configuring the shield to carry the shield signal. 
     
     
       5. The method of  claim 1 , wherein reducing the effect of parasitic capacitance includes both offsetting the effect that the parasitic capacitance has on a phase of the one or more touch signals and attenuating an amount of parasitic capacitance in the touch sensor panel. 
     
     
       6. The method of  claim 1 , wherein configuring the touch sensor panel to the self-capacitance architecture includes switching a mutual capacitance touch detection hardware configuration into a self-capacitance touch detection hardware configuration. 
     
     
       7. The method of  claim 1 , further comprising:
 scanning one or more electrodes in the touch sensor panel to obtain the one or more touch signals. 
 
     
     
       8. The method of  claim 7 , wherein determining if a proximity event has occurred further comprises:
 determining a touch signal level of one or more of the reduced parasitic capacitance effect touch signals; 
 computing an average touch signal for one or more of the reduced parasitic capacitance effect touch signals; and 
 comparing the average touch signal with a pre-determined threshold value. 
 
     
     
       9. An apparatus for detecting proximity events, comprising:
 driving circuitry configured for stimulating a touch sensor panel with one or more stimulation signals to generate one or more touch signals indicative of changes in self-capacitance; 
 a parasitic capacitance reduction system configured for reducing an effect of parasitic capacitance on the one or more touch signals received from the touch sensor panel by causing the driving circuitry to drive a shield with a shield signal of a same frequency and phase as the one or more stimulation signals, wherein the shield is a physical layer separate from other conductive structures in the touch sensor panel; and 
 sensing circuitry capable of determining if a proximity event has occurred based on the one or more reduced parasitic capacitance effect touch signals. 
 
     
     
       10. The apparatus of  claim 9 , wherein the apparatus is further configured to be switchable to detect changes in mutual capacitance in the touch sensor panel. 
     
     
       11. The apparatus of  claim 9 , wherein the parasitic capacitance reduction system includes a phase noise calibration system for calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals. 
     
     
       12. The apparatus of  claim 9 , wherein the parasitic capacitance reduction system includes a parasitic capacitance attenuation system for lowering a magnitude of the parasitic capacitance present in the touch sensor panel. 
     
     
       13. The apparatus of  claim 9 , wherein the parasitic capacitance reduction system includes:
 a phase noise calibration system for calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals; and 
 a parasitic capacitance reduction system for lowering a magnitude of the parasitic capacitance present in the touch sensor panel. 
 
     
     
       14. The apparatus of  claim 9 , wherein the sensing circuitry is further capable of scanning one or more electrodes in the touch sensor panel to obtain the one or more touch signals. 
     
     
       15. The apparatus of  claim 9 , wherein the sensing circuitry is further capable of determining the occurrence of the proximity event by determining a touch signal level indicative of a proximity event, computing an average touch sensor panel signal level, and comparing the computed average touch panel signal level with the determined touch signal level. 
     
     
       16. A non-transitory computer readable storage medium having stored thereon a set of instructions for detecting proximity events in a touch sensor panel, that when executed by a processor causes the processor to:
 configure a touch sensor panel to detect changes in a self-capacitance on a plurality of electrodes in the touch sensor panel; 
 stimulate the touch sensor panel with one or more stimulation signals to generate one or more touch signals indicative of the changes in self-capacitance; 
 reduce a parasitic capacitance effect on the one or more touch signals received from the plurality of electrodes by driving a shield with a shield signal of a same frequency and phase as the one or more stimulation signals, wherein the shield is a physical layer separate from other conductive structures in the touch sensor panel; and 
 determine if a proximity event has occurred based on the one or more reduced parasitic capacitive effect touch signals. 
 
     
     
       17. The non-transitory computer readable storage medium of  claim 16 , wherein configuring the touch sensor panel includes switching the touch sensor panel from a mutual capacitance touch sensor panel to a self-capacitance touch sensor panel. 
     
     
       18. The non-transitory computer readable storage medium of  claim 16 , wherein reducing the parasitic capacitance effect includes calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals. 
     
     
       19. The non-transitory computer readable storage medium of  claim 16 , wherein reducing the parasitic capacitance effect includes attenuating an amount of parasitic capacitance in a touch sensor panel. 
     
     
       20. The non-transitory computer readable storage medium of  claim 16 , wherein reducing the parasitic capacitance effect includes both attenuating an amount of parasitic capacitance in the touch sensor panel and calibrating out an effect of the parasitic capacitance on a phase of the one or more touch signals. 
     
     
       21. The non-transitory computer readable storage medium of  claim 16 , further comprising scanning one or more electrodes in the touch sensor panel to obtain the one or more touch signals. 
     
     
       22. The non-transitory computer readable storage medium of  claim 16 , wherein determining if the proximity event has occurred includes:
 determining a touch signal value indicative of a proximity event; 
 computing an average electrode signal value for one or more of the reduced parasitic capacitance effect touch signals; and 
 comparing the average signal value with the determined touch signal value. 
 
     
     
       23. The method of  claim 6 , further comprising:
 configuring a first set of multiple lines as sense electrodes in the self-capacitance touch detection hardware configuration by applying at least some of the one or more stimulation signals to the first set of multiple lines through one or more virtual ground charge amplifiers, and configuring the first set of multiple lines as drive lines in the mutual capacitance touch detection hardware configuration; and 
 configuring a second set of multiple lines as sense electrodes in either the self-capacitance touch detection hardware configuration or the mutual capacitance touch detection hardware configuration. 
 
     
     
       24. The method of  claim 23 , wherein configuring the first set of multiple lines as sense electrodes comprises coupling the one or more virtual ground charge amplifiers to the first set of multiple lines. 
     
     
       25. The method of  claim 24 , further comprising reducing the effect of parasitic capacitance by:
 applying a sinusoidal signal to a positive input of at least one of the one or more virtual ground charge amplifiers; and 
 driving the shield with the shield signal having substantially the same frequency and phase as the sinusoidal signal. 
 
     
     
       26. The apparatus of  claim 10 , further comprising:
 a plurality of input/output (I/O) lines for connecting to the touch sensor panel; 
 wherein the sensing circuitry includes one or more sense amplifiers configured for receiving sense signals through at least some of the plurality of I/O lines; 
 wherein the driving circuitry is couplable to the one or more sense amplifiers and configurable for providing the one or more stimulation signals to at least some of the plurality of I/O lines in a self-capacitance configuration; and 
 wherein the apparatus further comprises switching circuitry coupled to the plurality of I/O lines, a plurality of drivers, and the one or more sense amplifiers, the switching circuitry configured for coupling the plurality of drivers to at least some of the plurality of I/O lines in a mutual capacitance configuration, and for coupling the one or more sense amplifiers to at least some of the plurality of I/O lines and applying the one or more stimulation signals to at least some of the plurality of I/O lines through the one or more sense amplifiers in the self-capacitance configuration. 
 
     
     
       27. The non-transitory computer readable storage medium of  claim 17 , the method further comprising:
 configuring a first set of multiple lines as sense electrodes in a self-capacitance touch detection hardware configuration by applying at least some of the one or more stimulation signals to the first set of multiple lines through one or more virtual ground charge amplifiers, and configuring the first set of multiple lines as drive lines in a mutual capacitance touch detection hardware configuration; and 
 configuring a second set of multiple lines as sense electrodes in either the self-capacitance touch detection hardware configuration or the mutual capacitance touch detection hardware configuration. 
 
     
     
       28. The non-transitory computer readable storage medium of  claim 27 , wherein configuring the first set of multiple lines as sense electrodes comprises coupling the one or more virtual ground charge amplifiers to the first set of multiple lines. 
     
     
       29. The non-transitory computer readable storage medium of  claim 28 , the method further comprising reducing the effect of parasitic capacitance by:
 applying a sinusoidal signal to a positive input of at least one of the one or more virtual ground charge amplifiers; and 
 driving the shield with the shield signal having substantially the same frequency and phase as the sinusoidal signal.

Description:
FIELD OF THE DISCLOSURE 
     This relates generally to the detection of touch and proximity events on touch sensor panels, and more particularly, to the implementation of a touch sensor panel that can sense touch and proximity events over a wide dynamic range of distances. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens, and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens generally allow a user to perform various functions by touching (e.g., physical contact or near-field proximity) the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch event and the position of the touch event on the touch sensor panel, and the computing system can then interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event. 
     Mutual capacitance touch sensor panels can be formed from a matrix of drive and sense lines of a substantially transparent conductive material such as Indium Tin Oxide (ITO). The lines are often arranged orthogonally on a substantially transparent substrate. Mutual capacitance touch sensor panels not only have the ability to detect touch events on the touch sensor panels, but also have the ability to detect proximity events, in which an object is not touching the panel but is in close proximity to the panel. However, mutual capacitance touch pads are constrained in their ability to sense proximity events, and thus only provide proximity detection over a limited range of distances from the touch sensor panel. 
     SUMMARY OF THE DISCLOSURE 
     This relates to a touch sensor panel configured to detect objects that either are touching the panel or at a varying degree of proximity to the touch sensor panel. The panel can be configured to include circuitry that is capable of detecting objects that are touching the panel (near field events) using a mutual capacitance touch detection architecture, or can be configured to detect objects at a varying degree of proximity (far field and super far field) utilizing a projection scanning self-capacitance architecture. Furthermore, in order to facilitate the detection of proximity events at varying distances away from the touch panel, a parasitic capacitance of the touch sensor panel can be reduced to make proximity event detection more reliable as the distance that the object is from the touch sensor panel increases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  illustrates an exemplary mutual capacitance touch sensor circuit according to one disclosed embodiment. 
         FIG. 1   b  illustrates an exemplary touch node and the effect that a finger touching the node has on coupled charge according to one disclosed embodiment. 
         FIG. 1   c  illustrates another exemplary touch node and the effect that the absence of a finger has on coupled charge according to one disclosed embodiment. 
         FIG. 2  illustrates an exemplary self-capacitance touch sensor circuit according to one disclosed embodiment. 
         FIG. 3   a  illustrates an exemplary electrical circuit corresponding to a self-capacitance touch sensor electrode according to one disclosed embodiment. 
         FIG. 3   b  illustrates an exemplary electrical circuit corresponding to a self-capacitance touch sensor electrode when a parasitic capacitance is present on the touch electrode according to one disclosed embodiment. 
         FIG. 4   a  illustrates an exemplary relationship between Cself and parasitic capacitance when a hand or object is near the self-capacitance touch sensor panel according to one disclosed embodiment. 
         FIG. 4   b  illustrates an exemplary relationship between Cself and parasitic capacitance when a hand or object is far from the self-capacitance touch sensor panel. 
         FIG. 5  illustrates an exemplary touch sensor system employing driven shielding according to one disclosed embodiment. 
         FIG. 6   a  illustrates an exemplary driven shielding circuit diagram of a touch electrode according to one disclosed embodiment. 
         FIG. 6   b  illustrates an exemplary driven shielding circuit diagram of a display according to one disclosed embodiment. 
         FIG. 6   c  illustrates an exemplary driven shielding circuit diagram of a border trace region according to one disclosed embodiment. 
         FIG. 7  illustrates an exemplary wide dynamic range self-capacitive touch sense circuit with voltage based offset according to one disclosed embodiment. 
         FIG. 8  illustrates a flow diagram illustrating an exemplary procedure to calibrate multiplying digital to analog converters according to one disclosed embodiment. 
         FIG. 9  illustrates an exemplary wide dynamic range self-capacitive touch sense circuit with current based offset according to one disclosed embodiment. 
         FIG. 10   a  illustrates an exemplary mutual capacitance touch sensor panel with a touch event occurring, and an exemplary corresponding touch resolution according to one disclosed embodiment. 
         FIG. 10   b  illustrates an exemplary self-capacitance touch sensor panel with a proximity event occurring, and an exemplary corresponding touch resolution according to one disclosed embodiment. 
         FIG. 11   a  illustrates an exemplary switching diagram for switching between a mutual capacitance touch sensor drive line configuration and a self-capacitance touch sensor electrode configuration according to one disclosed embodiment. 
         FIG. 11   b  illustrates an exemplary switching diagram for switching between a mutual capacitance touch sensor sense line configuration and a self-capacitance touch sensor electrode configuration according to one disclosed embodiment. 
         FIG. 12  illustrates a flow diagram illustrating an exemplary procedure to determine if a super far field proximity event is occurring on the touch sensor panel, according to one disclosed embodiment. 
         FIG. 13  illustrates an exemplary self-capacitance touch sensor panel in super far field detection mode with a super far field proximity event occurring, and an exemplary corresponding touch resolution according to one disclosed embodiment. 
         FIG. 14  illustrates a flow diagram illustrating an exemplary procedure for switching touch sensing modes during operation of the touch sensor panel according to one disclosed embodiment. 
         FIG. 15  illustrates a flow diagram for detecting the presence of a touch or proximity signal according to one disclosed exemplary embodiment. 
         FIG. 16  illustrates yet another flow diagram illustrating an exemplary procedure for switching touch modes during operation of the touch sensor panel according to one disclosed embodiment. 
         FIG. 17  illustrates an exemplary computing system including a touch sensor panel utilizing touch sensor common mode noise recovery according to one disclosed embodiment. 
         FIG. 18   a  illustrates an exemplary mobile telephone having a touch sensor panel that includes a touch common mode noise recovery circuit and method according to one disclosed embodiment. 
         FIG. 18   b  illustrates an exemplary digital media player having a touch sensor panel that includes a touch common mode noise recovery circuit and method according to one disclosed embodiment. 
         FIG. 18   c  illustrates an exemplary personal computer having a touch sensor panel that includes a touch common mode noise recovery circuit and method according to one disclosed embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific embodiments that can be practiced. It is to be understood that other embodiments can be used and structural changes can be made without departing from the scope of the disclosed embodiments. 
     This relates to a touch sensor panel which can have the ability to not only sense touch events but to also sense proximity events over a wide dynamic range of distances. The touch sensor panel hardware can be switched into various configurations depending on the range of distance that is desired to be sensed. Furthermore, the parasitic capacitance experienced by the touch sensor panel can be mitigated so that it does not act to distort the touch sensor panel&#39;s ability to detect touch and proximity events. Driven shielding can be employed to reduce parasitic capacitance, and the parasitic capacitance&#39;s effect on phase can be calibrated out to reduce its net effect on touch and proximity detection. 
     Although embodiments disclosed herein may be described and illustrated herein in terms of mutual capacitance and self-capacitance touch sensor panels, it should be understood that the embodiments are not so limited, but are additionally applicable to any capacitive touch sensor panel in which a wide dynamic range of detection is required. Additionally, although embodiments disclosed herein may be described and illustrated in terms of driven shielding being applied to one or more of a border trace area, a display area and electrodes, it should be understood that the embodiments are not so limited, but may be additionally applicable to any part of a touch input device which contributes parasitic capacitance to sense detection. Furthermore, although embodiments disclosed herein relate to a method of mitigating parasitic capacitance on a touch sensor panel, it should be understood that the embodiments are not so limited, but may be additionally applicable to any capacitive touch sensor device such as a capacitive trackpad. 
       FIG. 1   a  illustrates an exemplary touch sensor panel  100  according to some embodiments of the disclosure. Touch sensor panel  100  can include an array of touch nodes  106  that can be formed by a two-layer electrode structure separated by a dielectric material, although in other embodiments the electrodes can be formed on the same layer. One layer of electrodes can include a plurality of drive lines  102  positioned perpendicular to another layer of electrodes comprising a plurality of sense lines  104 , with each of the nodes  106  having an associated mutual capacitance  114  (also referred to as coupling capacitance), although in other embodiments, the drive and sense lines can be positioned in non-orthogonal arrangements. The drive lines  102  and sense lines  104  can cross over each other in different planes separated from one another by a dielectric. Each point in which a drive line  102  intersects a sense line  104  can create a touch node  106 . Thus, for example, a panel which contains for instance  20  drive lines  102  and  15  sense lines  104  will have 300 touch nodes available to detect touch or proximity events. 
     Drive lines  102  (also referred to as rows, row traces, or row electrodes) can be activated by a stimulation signal provided by respective drive circuits  108 . Each of the drive circuits  108  can include an alternating current (AC) or unipolar pulsatile voltage source referred to as a stimulation signal source. To sense touch event(s) on the touch sensor panel  100 , one or more of the drive lines  102  can be stimulated by the drive circuits  108 , and the sense circuitry  110  can detect the resulting change in the charge coupled onto the sense lines  104  in the form of a change in the amplitude of the coupled stimulation signal. The change in voltage amplitude values can be indicative of a finger or conductive object touching or in proximity to the panel. The detected voltage values can be representative of node touch output values, with changes to those output values indicating the node locations  106  where the touch or proximity events occurred and the amount of touch that occurred at those location(s). 
       FIG. 1   b  illustrates an exemplary touch node and the effect that a finger touching the node can have on coupled charge according to one disclosed embodiment. When drive line  102  is stimulated by a signal, electric field lines  118  can form between drive line  102  and sense line  104  due to the mutual capacitance between the drive and sense line, and charge can be coupled from the drive line to the sense line. When a finger or conductive object  116  comes into contact or near proximity to the touch node  106  created by the intersection of drive line  102  and sense line  104 , the object can block some of the electric field lines and the amount of charge coupled between the drive and sense line can decrease, with some of the charge being coupled into the finger or object. This decrease in charge coupled onto sense line  104  from drive line  102  can be detected by sense circuitry  110 . 
       FIG. 1   c  illustrates an exemplary touch node and the effect that the absence of a finger can have on coupled charge according to one disclosed embodiment. When finger  116  is removed from touch node  106 , the charge emanating from drive line  102  is no longer partially coupled into finger  116  and thus the amount of charge coupled into sense line  102  can increase. Finger  116  generally can only couple charge from the drive line  102  if it is touching or in near proximity to touch node  106  and blocking some electric field lines  118 . Once the finger  116  is moved away from touch node  106  and is a certain distance away from the node, then the charge is no longer coupled onto finger  116  and the touch sensor panel can no longer detect the presence of the finger and will not register a touch or proximity event. Thus, capacitive touch sensor panels which employ mutual capacitance to detect touch or proximity events often have a very limited range of distance over which the system can detect proximity events. 
     Touch sensor panels that employ self-capacitance to detect touch or proximity events can be used to detect the presence of a finger or object that is further away from the touch sensor panel than a panel which uses mutual capacitance.  FIG. 2  illustrates an exemplary self-capacitance touch sensor circuit  200  according to one disclosed embodiment. Self-capacitive touch sensor panel circuit  200  contains electrodes  202  which are connected to sense circuitry  204  and have a self-capacitance to ground. When an object touches or is in close proximity with the electrode, an additional capacitance can be formed between the electrode and ground through the object, which can increase the self-capacitance of the electrode. This change in the self-capacitance of an electrode  202  can be detected by sensing circuit  204 . Changes in self-capacitance can be created when objects or fingers are further away from the touch panel, as opposed to mutual capacitance touch panels which require the finger or object to be either touching or in near proximity to panel in order to sense a touch or proximity event. Unlike mutual capacitance touch sensor  100 , each electrode of the circuit acts as a touch node, rather than the intersections of orthogonal electrodes. Thus in 20×15 electrode array, there are only 35 touch nodes. One skilled in the art will recognize that such a self-capacitance architecture can possess a touch resolution that is less than the mutual capacitance touch resolution (e.g., 35 nodes vs. 300 nodes). Since the self-capacitive architecture described above has a reduced spatial resolution when compared to a mutual capacitive touch sensor, a self-capacitive touch sensor panel may not be able to detect touch or proximity event location with as much accuracy or unambiguity as a mutual capacitive touch sensor panel. 
       FIG. 3   a  illustrates an exemplary electrical circuit corresponding to a self-capacitance touch sensor electrode and sensing circuit according to one disclosed embodiment. Electrode  202  can have a self-capacitance  304  to ground associated with it. Touch electrode  202  can be coupled to sensing circuit  314 . Sensing circuit can include an operational amplifier  308 , feedback resistor  312 , feedback capacitor  310  and an input voltage source  306 , although other configurations can be employed. For example, feedback resistor  312  can be replaced by a switched capacitor resistor in order to minimize any parasitic capacitance effect caused by a variable feedback resistor. The touch electrode can be coupled to the inverting input of operation amplifier  308 . An AC voltage source  306  (Vac) can be coupled to the non-inverting input of operation amplifier  308 . The touch sensor circuit  300  can be configured to sense changes in self-capacitance  304  induced by a finger or object either touching or in proximity to the touch sensor panel. The output  320  of the touch sense circuit  300  is used to determine the presence of a proximity event. The output  320  can either be used by a processor to determine the presence of a proximity or touch event, or output  320  can be inputted into a discrete logic network to determine the presence of a touch or proximity event. 
       FIG. 3   b  illustrates an exemplary electrical circuit corresponding to a self-capacitance touch sensor electrode and sensing circuit when a parasitic capacitance is present on the touch electrode according to one disclosed embodiment. Parasitic capacitance  314  can represent capacitances found on touch electrode  202  that can be derived from various sources on a device which employs a touch sensor panel. As an example, parasitic capacitance can be created by the interaction between the touch electrodes  202  and other circuitry of the device such as a display or other conductive plates that can exist within a device which employs a touch sensor panel. One of ordinary skill in the art will recognize that in a self-capacitance touch sensing system, parasitic capacitance  314  (Cpar) will be in parallel to the self-capacitance  304  as shown in  FIG. 3   b . When two capacitors are in parallel they add together, thus the change in capacitance being measured by sense circuit  314  can be Cself+Cpar, where Cself represents the signal of interest which is the self-capacitance of electrode  202 . Since sense circuit  314  detects a combination of self-capacitance  304  and parasitic capacitance  314 , the relationship between self-capacitance  304  and parasitic capacitance  314  can be important. 
     For instance, one skilled in the art will recognize that the equation for output  320  (Vout) of sense circuit  300  can be represented as:
 
 V   OUT   =V   AC *[(1 +Cc×F/GJ )+ j ( Ce×H/G )]
 
     Where
         F=C sb *(ω*R sb ) 2      G=1+(ω*R fb *C sb ) 2      H=ω*R sb      C e =Cself+C par          

     As expressed in the equation above, the phase of output  320  is dependent upon the value of Cself and Cpar. Thus, Cpar produces a phase offset and can hinder sense circuitry  204 &#39;s ability to detect proximity events. In the equations above, a can be defined as the frequency of the stimulation signal applied to the electrodes via the non-inverting input of operational amplifier  308  represented in the equations above as Vac. If Vac is a sinusoidal signal then the equation above can be simplified such that: 
     If V AC =Sin(ωt) then 
     V AC =Sin(ωt+β+φ) 
     ∅=phase shift caused by C par    
     β=phase shift caused by Cself 
     Also, the magnitude of parasitic capacitance  314  in relation to the magnitude of self-capacitance  304  can have an effect on how accurately sense circuit  314  is able to detect changes in self-capacitance created by a finger or object in proximity to touch electrode  202 .  FIG. 4   a  illustrates an exemplary relationship between Cself and parasitic capacitance when a hand or object is near the self-capacitance touch sensor panel. As illustrated, when hand  402  is a short distance  410  from touch panel  404 , the magnitude of Cself (self-capacitance)  406  is larger than the magnitude of Cpar (parasitic capacitance)  408 . Note that the magnitudes are illustrative and shown for purposes of relative comparison only, and are not intended to represent actual magnitudes. If Cself  406  is considered the signal of interest and Cpar  408  is considered a noise source, then the touch sensor panel  404  can be said to have a good signal to noise ratio (SNR), thus making touch and proximity detection more reliable. 
       FIG. 4   b  illustrates an exemplary relationship between Cself and parasitic capacitance when a hand or object is far from the self-capacitance touch sensor panel. When hand  402  increases its distance  410  from touch panel  404 , the magnitude of Cself  406  can become much smaller since Cself is inversely proportional to the distance that an object is located from the touch sensor panel. While fluctuations in distance  410  can cause fluctuations in the magnitude of Cself  406 , Cpar  408  can remain roughly constant. This means that as the hand  402  moves farther away from touch sensor panel  404 , the SNR of the sensor system can decrease. Eventually, when hand  402  is a certain distance  410  from touch sensor panel  404 , Cpar  408  can be said to “drown out” Cself  406 . In other words, the magnitude of Cpar  408  can be so great as compared to the magnitude of Cself  406  that touch sense circuitry  204  may no longer be able to detect changes in Cself. Furthermore, as the magnitude of Cself becomes smaller, more gain from touch sensing circuit  314  may be required, in order to allow detection of changes in Cself. However, if the magnitude of Cpar  408  is too great, then operation amplifier  308  can become saturated and thus may not be able to provide adequate signal gain to sense changes in Cself. 
     These relationships between Cself and Cpar can mean that a self-capacitance touch sensor panel&#39;s performance over distance can be constrained by at least two factors: the distance  410  that a hand or object  402  is away from touch panel  404 , and the amount of parasitic capacitance  408  present on the touch sensor panel  404 . In order to achieve an acceptable SNR across a wide dynamic range of distance, parasitic capacitance  408  can be reduced or eliminated so that its magnitude relative to Cself is small, and its energy does not saturate amplifier  308  and reduce the amplifier&#39;s ability to provide adequate gain to measure Cself. 
     Thus, in order to increase the dynamic range within which proximity events can be detected, the effect that parasitic capacitance has on touch and proximity event detection can be mitigated in order to allow for errors in proximity event detection to be minimized. According to one embodiment, mitigating parasitic capacitance can involve attenuating the magnitude of Cpar so that its magnitude in relation to the magnitude Cself is small. Driven shielding can be used to attenuate parasitic capacitance.  FIG. 5  illustrates an exemplary touch sensor system employing driven shielding according to one disclosed embodiment. Driven shielding touch sensor system  500  can include touch controller  516  which can drive the touch sensor panel  502  with stimulation signals via electrode traces  506 , and process touch signals outputted by touch input device  502 . Touch sensor panel  502  may contain a display and a border trace area which can be encapsulated or otherwise protected by a conductive display shield  512  for the display and conductive border trace shield  504  for the border trace area (e.g., one or more shield layers in the display and/or border trace stackus). Border trace shield  504  and display shield  512  can conduct a signal Vshield  510  generated by touch controller  516 . Electrode traces  506  can also have a shield  508  encapsulating them (e.g., one or more shield layers in a flex circuit stackup). Vshield  510  can drive electrode trace shield  508  and display shield  512 . 
       FIG. 6   a  illustrates an exemplary shielding circuit diagram of a touch electrode layer in a flex circuit according to one disclosed embodiment. In a touch or near-field proximity sensing configuration, touch controller  608  can output a stimulation signal onto row electrode traces on layer  602 . Touch electrode layer  602  can be encapsulated (e.g., covered on top and/or bottom) by one or more conductive shields  604 . Conductive shields  604  can be connected to Vshield  610 , which can provide a DC reference voltage (in touch or near-field proximity sensing embodiments) or an AC signal (in far-field proximity sensing embodiments) to the conductive shield  604 . In far-field proximity sensing embodiments, Vshield  610  can be configured to carry either the same or a similar signal to the signal being carried on electrode  602 . If the signals on the shield  604  and the electrode  602  are about the same, then parasitic capacitive effects caused by the electrodes can be attenuated or even eliminated since the effective capacitance between two conductive plates at the same voltage is zero. By encapsulating the electrode  602  within conductive sheath  604 , and then driving conductive sheath  604  with a Vshield  510  which carries an identical or nearly identical signal as the signal being transmitted on the electrode, the change in voltage between the conductive plate of the electrode and the conductive plate of the shield can be zero or nearly zero, meaning parasitic capacitances contributed by the electrode&#39;s interaction with other conductive plates in the system can be attenuated. 
     In some embodiments such as far-field proximity sensing which utilize self-capacitive touch detection as described above, and as illustrated in the circuit diagram of  FIG. 3   b , touch electrode  202  can receive signal Vac  306  during touch detection. Thus, if electrode  202  is shielded with a conductive shield  604 , and Vshield  602  is set to equal Vac  306 , then the driven shield can attenuate the portion of the total parasitic capacitance caused by the electrode&#39;s  202  interaction with other conductive plates. 
       FIG. 6   b  illustrates an exemplary driven shielding circuit diagram of a display according to one disclosed embodiment. Touch controller  608  can output a signal Vshield  510  that drives display shield  614 , which can encapsulate (e.g., cover on top and/or bottom) display  612 . Similar to the description given for the touch electrode  902  of  FIG. 9   a , in far-field proximity sensing the display shield  614  can be driven with a signal that is similar or identical to the signal being carried on the electrodes, in order to attenuate parasitic capacitance. 
       FIG. 6   c  illustrates an exemplary driven shielding circuit diagram of a border trace region according to one disclosed embodiment. Touch controller  608  can output a signal Vshield  510  that drives border trace shield  624 , which can encapsulate (e.g., cover on top and/or bottom) border trace region  622 . Similar to the description given for the touch electrode  602  of  FIG. 6   a , and display  612  of  FIG. 6   b , in far-field proximity sensing the border trace shield  624  can be driven with a signal that is similar or identical to the signal being carried on the electrodes in order to attenuate parasitic capacitance. 
     While the driven shielding method above can attenuate substantially all of the parasitic capacitance of the touch sensor panel, some residual parasitic capacitance may remain, thus it may be necessary to employ a second method to mitigate parasitic capacitance. According to another embodiment, mitigating parasitic capacitance can also involve offsetting the phase shift associated with parasitic capacitance, so that the parasitic capacitance&#39;s contribution to phase noise can be reduced or eliminated. 
       FIG. 7  illustrates an exemplary wide dynamic range self-capacitive touch sense circuit with voltage based offset according to one disclosed embodiment. The voltage based offset circuit  700  can be used to offset phase offset caused by parasitic capacitance. Voltage based offset circuit  700  can contain two multiplying digital to analog converters (DAC)  702  and  710 . The two multiplying DACs produce signals that, when added to the sensed signal, can reduce or eliminate the phase offset due to parasitic capacitance. The first multiplying DAC  702  receives signal  704  which is a digital value representative of a value between 1 and −1 which can be expressed as sin(Ω), and a sinusoidal signal  706  equivalent to cos(ωt), which represents a sinusoid with the same frequency as the output of touch sense circuit  316 . With those inputs, multiplying DAC  702  can produce an output signal  708  (Vc), which represents the simple product of its two inputs expressed below in equation form.
 
 V   C =Cos(ω t )Sin(Ω)
 
     The second multiplying DAC  710  receives signal  712  which is a digital value representative of a value between 1 and −1 which can be expressed as cos(Ω), and a sinusoidal signal  714  equivalent to sin(ωt). With those inputs, multiplying DAC  510  can produce an output signal  516  (Vs), which represents the simple product of its two inputs.
 
 V   S =Sin(ω t )Cos(Ω)
 
     The value of Ω can be determined during a calibration procedure which will be described below. 
     When no touch is present on the touch panel the change in Cself=0. Ideally when no touch is present, the output of touch sense circuit  314 , denoted as Vout  316 , should equal to 0. However due to parasitic capacitance, even when a touch signal is not present, Vout  316  can have a value equal to:
 
 V out=Sin(ω t +φ)
 
     Thus in order to calibrate out effects due to parasitic capacitance, when no touch event is occurring it is desired to have the output of the summing circuit at junction  520 =0, since this would be the output if the change in Cself was 0 and no parasitic capacitance was present. When no touch signal is present, the equation which characterizes the output at junction  720  is equal to:
 
 V out− Vc−Vs =Sin(ω t +φ)−Cos(ω t )Sin(Ω)−Sin(ω t )Cos(Ω)
 
     Since the goal of calibration is to make the output at junction  720  equal to 0 when no touch signal is present, the equation above becomes Vout−Vs−Vc=0
 
 V out− Vc−Vs =Sin(ω t +φ)−Cos(ω t )Sin(Ω)−Sin(ω t )Cos(Ω)=0
 
     Using standard trigonometric identities Vc+Vs can be simplified as:
 
 V   S   +V   C =Cos(ω t )Sin(Ω)+Sin(ω t )Cos(Ω)
 
 V   S   +V   C =Sin(ω t +(Ω))
 
     Using the above simplification, the equation for Vout−Vc−Vs becomes
 
Sin(ω t +φ)−Sin(ω t +Ω)=0
 
Sin(ω t +Ω)=Sin(ω t +φ)
 
     Thus: Ω=φ 
     In order to get the output of junction  720  to equal 0 when no touch is present, the multiplying DAC&#39;s  704  and  712  can be programmed with a value of Ω such that Ω=φ. 
       FIG. 8  illustrates a flow diagram illustrating an exemplary procedure to calibrate multiplying digital to analog converters according to one disclosed embodiment. At step S 1 , an initial value of Ω can be set and provided to multiplying DAC&#39;s  702  and  710 . At step S 2 , the output of junction  520  can be checked to determine if its value is 0. If it is 0, then the calibration procedure can be terminated. If it is not 0, then the process moves to S 3  and Ω can be adjusted to a new value. At step S 4 , the output value of junction  520  can be checked to determine if its value is 0. If it is, then the process moves to step S 5  where is the process can be terminated. If it is not 0, then the process goes back to S 3  and repeats. Eventually, a value of Ω can be found such that the output of junction  520  is 0. When this is achieved, the effect that parasitic capacitance has on phase can effectively be calibrated out. One skilled in the art will recognize that the procedure detailed in  FIG. 8  is just one method of determining the phase offset. In other embodiments the offset can also be computed by measuring the phase offset on the output of an in-phase and quadrature phase demodulation architecture. 
       FIG. 9  illustrates an exemplary wide dynamic range self-capacitive touch sense circuit with current based offset according to one disclosed embodiment. A current based offset can act in the same manner as the voltage based offset method described above, the only difference being that resistors  708 ,  716  and  718  of  FIG. 7  are no longer needed to convert the current to voltage, and the voltages do not need to be summed as demonstrated in  FIG. 7  at junction  720 . As shown in  FIG. 9 , multiplying DACs  902  and  910  are driven by sinusoidal signals  906  and  914  respectively, and have a digital gain value  904  and  912  as an input. The current produced by each multiplying DAC is combined with the current produced by the sense circuit, and the gains of the multiplying DAC&#39;s are adjusted until the combined current is equal to 0 in a manner described above in relation to  FIG. 7  and  FIG. 8 . 
     While self-capacitance touch sensor panels that mitigate parasitic capacitance, as described above, can detect proximity events at a greater distance than using a mutual capacitive touch sensor panel, they can often have less resolution than a mutual capacitance touch sensor panel and can, in projection scan configurations, produce ambiguous results. Touch or proximity resolution can mean the degree of accuracy to which the object&#39;s location on the touch sensor panel can be determined.  FIG. 10   a  illustrates an exemplary mutual capacitance touch sensor panel with a touch event occurring, and an exemplary corresponding touch resolution. As shown, mutual capacitive touch sensor panel  1002  can receive either a touch event or a near proximity event  1004 . When touch event  1004  is occurring, the matrix  1006  composed of intersecting drive electrodes  102  and sense electrodes  104  can register a touch event at touch node  1008 . 
       FIG. 10   b  illustrates an exemplary self-capacitance touch sensor panel with a proximity event occurring, and an exemplary corresponding proximity resolution. As shown, self-capacitance touch sensor panel  1010  can detect proximity events from objects  1012  that are a distance  1014  away from the touch sensor panel. When a proximity event is occurring, the touch matrix  1016  composed of electrodes  202  can register a proximity event occurring over a region  1018 . Region  1018  covers a larger area than touch node  1008  and thus the panel  1010  can only sense that a proximity event is occurring within a certain region of the panel, as compared to the mutual capacitance  1002  which can detect touch events to the specific node  1008  where the event is occurring. 
     However, because only coarse resolution may be required when detecting far-field proximity events, while fine resolution may be required when detecting touch or near-field proximity events, both types of touch sensing can be advantageous at different times (e.g., as an object approaches and eventually touches a touch-sensitive surface) or in different applications (e.g., detecting touch gestures vs. detecting an approaching user to turn on a device). Thus, a device which can detect touch or near proximity events with fine resolution, and detect proximity events further away with coarser resolution, can be beneficial. 
     According to some embodiments, a device that contains both a mutual capacitance and a self-capacitance touch sensor panel working in parallel can achieve the goal of having a touch sensor panel which can do both mutual capacitance touch sensing and self-capacitance touch sensing simultaneously in one device. According to other embodiments, a touch sensor panel that is able to switch its configuration to a mutual capacitance configuration to detect touch or near field proximity events, and switch its configuration to a self-capacitance configuration to detect far field proximity events can also achieve the goal of having a touch sensor panel which can do both mutual capacitance touch sensing and self-capacitance touch sensing in one device. 
       FIG. 11   a - 11   b  illustrates an exemplary switching diagram for switching between a mutual capacitance touch sensor configuration and a self-capacitance touch sensor configuration. Switching can be achieved by changing the configuration of the drive lines of a mutual capacitance touch sensor panel to a self-capacitance touch electrode configuration, and vice versa.  FIG. 11   a  illustrates an exemplary switching diagram for switching between a mutual capacitance touch sensor drive line configuration and a self-capacitance touch sensor electrode configuration according to one disclosed embodiment. Touch controller  1112  can send a signal to switches  1108  and  1110  to either engage a near field mutual capacitance system (which includes touch) or to engage a far field self-capacitance system. Switches  1108  and  1110  form an input/output (I/O) line that can be connected to touch electrode  1120  on the touch sensor panel. If a near field configuration is desired, then touch controller  1112  will close switch  1108  and open switch  1110 . With switch  1108  closed, touch electrode  1120  can be either connected to electrode driver  1102 , or a reference voltage  1104  (e.g., ground) depending on the position of switch  1106 . It should be understood that driver  1102 , switch  1106  and reference voltage  1104  are merely symbolic, and that other configurations that achieve the same result are contemplated. When the row corresponding to drive electrode  1120  is being stimulated, then switch  1106  will connect to electrode driver  1102 . When the row is not being stimulated then switch  1106  will be switched to reference voltage  1104 . Note that in some embodiments, all of the circuitry in  FIG. 11A  can reside in the touch controller  1112 . 
     If a far field configuration is desired, then touch controller  1112  can open switch  1108  and close switch  1110 . When switch  1110  is closed, electrode  1120  is connected to operational amplifier  308 . Operational amplifier can be configured as a noninverting amplifier in the self-capacitance sensing configuration illustrated in  FIG. 3   a  with feedback resistor  312  and feedback capacitor  310  connected between its output and its inverting input, and Vshield  306  outputted by touch controller  1112  to its non-inverting input. Drive electrode  1102  and ground  1104  are no longer connected to electrode  1120 . 
     In some embodiments, the exemplary circuitry of  FIG. 11A  can be replicated for every touch electrode  1120 . In other embodiments, the drivers  1102  and/or amplifiers  308  can be multiplexed so that fewer drivers and/or amplifiers can be utilized as compared to the number of electrodes. In some embodiments, feedback resistor  312  and feedback capacitor  310  can be switched to include other capacitors and resistors, depending on the value required for super far field and far field sensing. Thus, while one set of resistor and capacitor values can be used for super far field sensing, when electrode  1120  is switched to far field sensing, feedback resistor  312  can be reconfigured to a different resistance, and feedback capacitor  310  can be reconfigured to a different capacitance. 
       FIG. 11   b  illustrates an exemplary switching diagram for switching between a mutual capacitance touch sensor sense line configuration and a self-capacitance touch sensor electrode configuration according to one disclosed embodiment. Operational amplifier  308  can be configured similar to  FIG. 3   a  and is described above. When touch sense electrode  1130  is configured for near field sensing, touch controller  1112  can output a DC signal to the non-inverting input of operational amplifier  308 . When touch sense electrode  1130  is configured for far field sensing, touch controller  1112  can output a signal Vshield to the non-inverting input of operational amplifier  308 . Furthermore, feedback resistor  312  and feedback capacitor  310  can be switched to different values, depending on the requirements of configuration. It should be noted that the circuits of  FIGS. 11   a  and  11   b  are merely exemplary, and that other components and configurations that perform a similar function can also be used. 
     As illustrated in  FIGS. 4   a  and  4   b , as an object  402  such as a hand or stylus moves further away from the self capacitance touch sensor panel  404 , the value of Cself becomes smaller and is inversely proportional to the distance  410  that the object is away from touch sensor panel. The gain provided to Cself in each detection mode can be set to optimize the ability to detect the expected signal. For example, the super far field gain can be set to the highest possible value in order to detect the most distant objects. However despite optimizing the gain, eventually, when the object  402  is far enough away from touch sensor panel  404 , the value of Cself can become so small that a proximity event can no longer be distinguished from random variations in self capacitance due to various noise sources in the touch sensor panel. In other words, the rise in Cself caused by a proximity event cannot be distinguished from a rise in Cself caused by random system noise. However, if a proximity event is occurring in the super far field (a distance in which a proximity event signal on a single electrode cannot be distinguished from noise) then if the value of Cself on a plurality or all of the electrodes on touch sensor panel  404  is averaged, then a rise in the average Cself of the entire panel can indicate that a super far field proximity event is occurring. 
       FIG. 12  illustrates an exemplary flow diagram illustrating the procedure to determine if a super far field proximity event is occurring on the touch sensor panel, according to one disclosed embodiment. With the touch sensor panel is in a self-capacitance configuration, at step S 1200  each or at least a plurality of electrodes in the touch sensor panel are scanned (measured) and Cself for each scanned electrode is determined. At step S 1202  each measured value of Cself is used to determine an average Cself. The average Cself represents the average self capacitance that each electrode is experiencing during the scan at S 1200 . At step S 1204  the average Cself calculated in step S 1202  is compared against a pre-determined threshold value. If the average Cself is above the threshold, then the flow moves to step  1208  in which the touch controller processor  810  indicates that a proximity event is occurring. If the average Cself is below a pre-determined threshold, then the flow moves to step S 1206  and touch controller  810  indicates no proximity event is occurring. Although averaging of Cself is described above, in other embodiments super far field proximity events can be detected by combining multiple Cself values in other ways. 
       FIG. 13  illustrates an exemplary self-capacitance touch sensor panel in super far field detection mode with a super far field proximity event occurring, and an exemplary corresponding touch resolution according to one disclosed embodiment. When touch sensor panel  1302  is in a super far field sensing mode, an object  1304  a distance  1306  away from the touch sensor panel can register a proximity event. Touch sensor electrode matrix  1308  composed of electrodes  202  can register a proximity event occurring over a region  1310 . Since the average Cself of the multiple electrodes in the panel can be used to determine if a proximity event is occurring, the touch resolution of the panel can be poor. As shown, region  1310  covers the entire panel and thus, while the touch sensor panel  1302  is registering a proximity event, the precise location is unknown. The touch sensor panel only registers that a proximity event is occurring, but does not know where the event is occurring. In other embodiments, region  1310  may not cover the entire panel, but a significant portion of the panel. 
     As described above, the touch sensor panel can have three modes of operation available to operate in. The first mode, near field mutual capacitive touch sensing, can be utilized to detect touch or near proximity events with a high degree of spatial resolution. The second mode, far field self-capacitive touch sensing, can be utilized to detect proximity events that are farther away from the touch sensor panel with a lower spatial resolution. Finally the third mode, super far field capacitive touch sensing, can be utilized to detect proximity events that are even farther away from the touch panel than far field detection but with little to no spatial resolution. 
     A device that includes a touch sensor panel capable of detecting signals in two or three of the modes described above, can determine which mode to operate in at any given time by a plurality of methods.  FIG. 14  illustrates a flow diagram illustrating an exemplary procedure for switching touch sensing modes during operation of the touch sensor panel according to one disclosed embodiment. At step S 1400  the touch sensor panel can be switched to a near field configuration as described above. If the touch sensor panel is already in the near field configuration, then no switching is necessary. At step S 1402 , the touch sensor panel can be scanned to determine if a signal is present. If a signal is found, then the flow moves to step S 1404  and the touch sensor panel will operate in a near field configuration. If no signal is detected, then the flow moves to step S 1406  and the touch sensor panel switches its configuration to a self-capacitance far field configuration. At step S 1408  the touch sensor panel can be scanned to determine if a signal is present. If a signal is detected, then the flow moves to step S 1410  and the touch sensor panel will operate in a far field configuration. If no signal is detected, then the flow moves to step S 1412  and the super far field detection method discussed above is used to detect super far field proximity events. At step  1414  the touch sensor panel can be scanned to determine if a signal is present. If a signal is detected, then the flow moves to step S 1416  and the touch sensor panel will operate in a super far field mode. If no signal is present, then the flow moves back to step S 1400  and the process is repeated. 
     The signal detection steps depicted at S 1402  and S 1408  can be accomplished using a plurality of methods.  FIG. 15  illustrates an exemplary flow diagram for detecting the presence of a touch or proximity signal according to one disclosed embodiment. At step  1500  the gain of amplifier  308  can be set to an initial value. In some embodiments, the gain of amplifier  308  can be set to an initial value by adjusting the value of feedback resistor  312 , either by switching out the resistor with a resistor of another value, or employing an adjustable resistor. In other embodiments, the gain of amplifier  308  can be set to an initial value by adjusting the value of feedback capacitor  310 , either by switching out the capacitor with a capacitor of another value, or employing an adjustable capacitor. Once the initial gain of amplifier  308  is set, the flow moves to step S 1502 , where the presence of a touch or proximity signal can be detected. If a signal is detected then the flow will move to step S 1504  and the process will indicate that a signal has been detected. If no signal is detected, then the flow will move to step  1506  where the gain will be adjusted using the methods described above. At step  1508  if a signal is detected then the flow will move to step S 1510  and the process will indicate that a signal has been detected. If no signal is detected, then the flow moves to step S 1512 . At step s 1512 , if the gain of the amplifier is at its maximum possible value, then the flow moves to S 1514  and the process indicates that no signal has been detected. If the gain is not at its maximum possible value, then the flow moves back to step S 1506  and the gain is adjusted and the process repeats. It should be understood that the above method is only meant to serve as an example, and the presence of a touch or proximity signal can be determined using other methods. 
       FIG. 16  illustrates yet another exemplary flow diagram illustrating the procedure for switching touch modes during operation of the touch sensor panel according to one disclosed embodiment. As step S 1600  the touch sensor panel is switched into a super far field configuration. The flow then moves to step  1602  where the touch sensor panel determines whether a signal has been detected. If no signal has been detected then the flow moves back to step S 1600  and the process is repeated. If a signal is detected then the flow moves to step S 1604  where the touch sensor panel is configured to operate in a far field sensing mode. At step S 1606  the touch sensor panel determines whether a signal has been detected. If no signal has been detected, then the flow moves to step S 1608  and the touch sensor panel is switched back to the super far field mode and the process is terminated at step S 1610 . If a signal is detected then the flow moves to step S 1612  and the device is switched to a near field configuration. The flow then moves to step S 1614  and the process searches for a signal. If no signal is detected, then the flow moves to step S 1618  and the touch sensor panel is switched to a far field configuration and the process is then ended at step  1620 . If a signal is detected then the process is stopped at S 1616 . 
       FIG. 17  illustrates exemplary computing system  1700  that can include one or more of the embodiments described above. Computing system  1700  can include one or more panel processors  1702  and peripherals  1704 , and panel subsystem  1706 . Peripherals  1704  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Panel subsystem  1706  can include, but is not limited to, one or more sense channels  1708  which can utilize operational amplifiers that can be configured to minimize saturation time, channel scan logic  1710  and driver logic  1714 . Channel scan logic  1710  can access RAM  1712 , autonomously read data from the sense channels and provide control for the sense channels including calibrating the sense channels for changes in phase correlated with a parasitic capacitance. In addition, channel scan logic  1710  can control driver logic  1714  to generate stimulation signals  1716  at various frequencies and phases that can be selectively applied to drive lines of touch sensor panel  1724 . In some embodiments, panel subsystem  1706 , panel processor  1702  and peripherals  1704  can be integrated into a single application specific integrated circuit (ASIC). 
     Touch sensor panel  1724  can include a capacitive sensing medium having a plurality of drive lines and a plurality of sense lines, although other sensing media can also be used. Each intersection of drive and sense lines can represent a capacitive sensing node and can be viewed as picture element (node)  1726 , which can be particularly useful when touch sensor panel  1724  is viewed as capturing an “image” of touch. Each sense line of touch sensor panel  1724  can drive sense channel  1708  (also referred to herein as an event detection and demodulation circuit) in panel subsystem  1706 . The drive and sense lines can also be configured to act as individual electrodes in a self-capacitance touch sensing configuration. 
     Computing system  1700  can also include host processor  1728  for receiving outputs from panel processor  1702  and performing actions based on the outputs 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 coupled 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  1728  can also perform additional functions that may not be related to panel processing, and can be coupled to program storage  1732  and display device  404  such as an LCD display for providing a UI to a user of the device. Display device  404  together with touch sensor panel  1724 , when located partially or entirely under the touch sensor panel, can form touch screen  1718 . 
     Note that one or more of the functions described above can be performed by firmware stored in memory (e.g. one of the peripherals  1704  in  FIG. 17 ) and executed by panel processor  1702 , or stored in program storage  1732  and executed by host processor  1728 . 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 that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
       FIG. 18   a  illustrates exemplary mobile telephone  1836  that can include touch sensor panel  1824  and display device  1830 , the touch sensor panel including circuitry to change the configuration of the touch sensor panel from a near field detection scheme to a far field and super far field detection scheme and mitigate the effects of parasitic capacitance according to one disclosed embodiment. 
       FIG. 18   b  illustrates exemplary digital media player  1840  that can include touch sensor panel  1824  and display device  1830 , the touch sensor panel including circuitry to change the configuration of the touch sensor panel from a near field detection scheme to a far field and super far field detection scheme and mitigate the effects of parasitic capacitance according to one disclosed embodiment. 
       FIG. 18   c  illustrates exemplary personal computer  1844  that can include touch sensor panel (trackpad)  1824  and display  1830 , the touch sensor panel and/or display of the personal computer (in embodiments where the display is part of a touch screen) including circuitry to change the configuration of the touch sensor panel from a near field detection scheme to a far field and super far field detection scheme and mitigate the effects of parasitic capacitance according to one disclosed embodiment. The mobile telephone, media player and personal computer of  FIGS. 12   a ,  12   b  and  12   c  can achieve a wider dynamic range of sensing capabilities by switching its configuration to detect near field and far field events, and mitigating parasitic capacitance. 
     Although  FIGS. 18   a - c  discuss a mobile telephone, a media player and a personal computer respectively, the disclosure is not so restricted and the touch sensor panel can be included on a tablet computer, a television, or any other device which utilizes the touch sensor panel including circuitry to switch between near field far field sensing configurations and mitigate the effects of parasitic capacitance on the touch sensor panel. 
     Although the disclosed embodiments 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 embodiments as defined by the appended claims.

Metadata:
Filing Date: 20120430
Publication Date: 20151201
Grant Date: 20151201
Priority Date: 20120430
Inventors: ELIAS JOHN GREER
HOTELLING STEVEN PORTER
Assignee: APPLE INC
CPC Classifications: [{"code": "H03K17/955", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04101", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/955", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04107", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04107", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04101", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04101", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F2203/04107", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/955", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 49476813