(12) United States Patent
`Hanauer et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,933,907 B2
`*Jan. 13, 2015
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`US008933907B2
`
`CAPACTIVE TOUCH SYSTEMUSING BOTH
`SELF AND MUTUAL CAPACITANCE
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`2/2010 Hotelling et al. ............. 345,173
`7,663,607 B2 *
`8,542,215 B2 * 9/2013 Hanauer et al. ...
`... 345,174
`8,577,644 B1 * 1 1/2013 Ksondzyk et al. .
`TO2,156
`8,723,825 B2 * 5/2014 Wright et al. ......
`... 345,173
`2007/0229468 A1* 10/2007 Peng et al. ...
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`2008/0048990 A1* 2, 2008 Cho et al. ....
`... 345,173
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`2009/0284495 A1 * 1 1/2009 Geaghan et al. ...
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`2010/0051354 A1* 3/2010 Ningrat et al. ...
`... 178.18.06
`2010/0073301 A1* 3/2010 Yousefpor et al. .
`... 345,173
`2011/0216038 A1* 9, 2011 Stolov et al. .................. 345,174
`OTHER PUBLICATIONS
`
`International PCT Search Report and Written Opinion, PCT/
`US2011/034228, 14 pages.
`(Continued)
`Primary Examiner — William Boddie
`Assistant Examiner — Mansour M Said
`(74) Attorney, Agent, or Firm — King & Spalding L.L.P.
`(57)
`ABSTRACT
`Systems and methods for determining multiple touch events
`in a multi-touch sensor System are provided. The system may
`have a touch sensor including nodes defined by a plurality of
`electrodes, which may comprise a first and second set. The
`method may include measuring self capacitance for at least
`two electrodes, detecting a touched electrode, and measuring
`the mutual capacitance for only a Subset of the nodes (e.g.,
`fewer than all of the nodes and including at least the nodes
`corresponding to the touched electrodes) resulting in the
`detection of two or more touched nodes. The self capacitance
`measurements may be performed on each of the electrodes,
`and the touched electrodes may comprise electrodes from
`both the first and second sets. Alternatively, the self capaci
`tance measurements may be performed only on electrodes in
`the first set, and the touched electrodes may comprise elec
`trodes from only the first set.
`27 Claims, 25 Drawing Sheets
`
`(54)
`
`(75)
`
`(73)
`
`Inventors: Jerry Hanauer, Germantown, WI (US);
`Todd O'Connor, Menomonee Falls, WI
`(US)
`Assignee: Microchip Technology Incorporated,
`Chandler, AZ (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 343 days.
`This patent is Subject to a terminal dis
`claimer.
`
`(21)
`
`Appl. No.: 13/089,701
`
`(22)
`
`Filed:
`
`Apr. 19, 2011
`
`(65)
`
`Prior Publication Data
`US 2012/O113047 A1
`May 10, 2012
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Related U.S. Application Data
`Provisional application No. 61/330,139, filed on Apr.
`30, 2010.
`
`(2006.01)
`(2006.01)
`
`Int. C.
`G06F 3/044
`G06F 3/04
`U.S. C.
`CPC .............. G06F 3/0416 (2013.01); G06F 3/044
`(2013.01); G06F 2203/04 104 (2013.01)
`USPC ........................................... 345/174; 34.5/173
`Field of Classification Search
`USPC ..................... 345/156-179; 178/18.01, 18.06
`See application file for complete search history.
`
`: 88:
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`8xx: 888:
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`US 8,933,907 B2
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`(56)
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`References Cited
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`OTHER PUBLICATIONS
`
`Rekimoto, Jun, "SmartSkin: An Infrastructure for Freehand Manipu
`lation on Interactive Surfaces.” CH12002: Changing the World,
`Changing Ourselves, vol. 4. No. 1, 9 pages, Apr. 20, 2002.
`Perme, Tom, "AN1101: Introduction to Capacitive Sensing.” Micro
`chip Technology Incorporated, 10 pages, Jul. 12, 2007.
`O'Connor, Todd, “TB3064: mTouchTM Projected Capacitive Touch
`Screen Sensing Theory of Operation.” Microchip Technology Incor
`porated, 16 pages, Aug. 24, 2010.
`International Search Report and Written Opinion, Application No.
`PCT/US2011/034236, 13 pages, Sep. 30, 2011.
`“Programmable Controller for Capacitance Touch Sensors.” Analog
`Devices, XP055105318, URL: http://web.archive.org/web/
`
`20090530075857. http://www.analog.com/static/imported-files/
`data sheets/AD7142.pdf, 72 pages, May 30, 2009.
`“CapTouch Programmable Controller for Single-Electrode Capaci
`tance Sensors.” Analog Devices, XP055105371, URL: http://web.
`archive.org/web/2009 1211123429/http://www.analog.com/static?
`imported-files/data sheets/AD7147.pdf, 72 pages, Dec. 11, 2009.
`European Office Action, Application No. 11718624.7, 8 pages, Mar.
`10, 2014.
`European Office Action, Application No. 11718624.7. 5 pages.
`“Capacitive Sensing.” Wikipedia, XP055081545, URL: http://en.
`wikipedia.org/w/windex.php?title=Capacitive sensing
`&oldid=424034475, 4 pages.
`European Office Action, Application No. 11718624.7, 7 pages.
`
`* cited by examiner
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`US 8,933,907 B2
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`1.
`CAPACTIVE TOUCH SYSTEMUSING BOTH
`SELF AND MUTUAL CAPACITANCE
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application claims the benefit of U.S. Provisional
`Application No. 61/330,139 filed on Apr. 30, 2010, entitled
`CAPACITIVE TOUCH SYSTEM USING BOTH SELF
`AND MUTUAL CAPACITANCE.” which is incorporated
`herein in its entirety.
`
`TECHNICAL FIELD
`
`The present disclosure relates to capacitive touch sensor
`systems, and more particularly, to an improved capacitive
`touch sensor System that uses both self and mutual capaci
`tance measurements to unambiguously detect one or more
`objects in contact or proximity with the Surface of a touch
`SSO.
`
`BACKGROUND
`
`Capacitive touch sensors are used as a user interface to
`electronic equipment, e.g., computers, mobile phones, per
`Sonal portable media players, calculators, telephones, cash
`registers, gasoline pumps, etc. In some applications, opaque
`touch sensors provide soft key functionality. In other appli
`cations, transparent touch sensors overlay a display to allow
`the user to interact, via touch or proximity, with objects on the
`display. Such objects may be in the form of soft keys, menus,
`and other objects on the display. The capacitive touch sensors
`are activated (controls a signal indicating activation) by a
`change in capacitance of the capacitive touch sensor when an
`object, e.g., a user's finger tip, causes the capacitance thereof
`to change.
`Today’s capacitive touch sensors come in different variet
`ies, including single-touch and multi-touch. A single-touch
`sensor detects and reports the position of one object in contact
`or proximity with the touch sensor. A multi-touch sensor
`detects the position of one or more objects in simultaneous
`contact or proximity with the touch sensor, and reports or acts
`upon distinct position information related to each object.
`A touch sensor used in both single- and multi-touch sys
`tems may be constructed using one or more layers, each
`having a plurality of electrodes electrically insulated from
`each other. In a multi-layer embodiment, the layers may be
`fixed in close proximity to each other and electrically insu
`lated from each other. In any of the one or more layer touch
`sensor constructions, the electrodes may form any type of
`coordinate system (e.g., polar, etc.). Some touch sensors may
`utilize an X-Y or grid-like arrangement. For example, in a
`two-layer construction, parallel electrodes on different layers
`may be arranged orthogonal to each other Such that the points
`of overlap between electrodes on the different layers defines
`a grid (or other coordinate system). In an alternative, single
`layer embodiment, the proximity relationship between one
`set of electrodes and another set of electrodes may similarly
`define a grid (or other coordinate system).
`Measuring the self capacitance of individual electrodes
`within the touch sensor is one method employed by single
`touch systems. For example, using an X-Y grid a touch con
`troller iterates through each of the X-axis and Y-axis elec
`trodes, selecting one electrode at a time and measuring its
`capacitance. The position of touch is determined by the proX
`imity of (1) the X-axis electrode experiencing the most sig
`
`2
`nificant capacitance change and (2) the Y-axis electrode expe
`riencing the most significant capacitance change.
`Performing self capacitance measurements on all X-axis
`and Y-axis electrodes provides a reasonably fast system
`response time. However, it does not support tracking multiple
`simultaneous (X,Y) coordinates, as required in a multi-touch
`sensor system. For example, in a 16x16 electrode grid, the
`simultaneous touch by one object at position (1.5) and a
`second object at position (4,10) leads to four possible touch
`locations: (1.5), (1,10), (4.5), and (4,10). A self-capacitance
`system is able to determine that X-axis electrodes 1 and 4
`have been touched and that Y-axis electrodes 5 and 10 have
`been touched, but it is not capable of disambiguating to deter
`mine which two of the four possible locations represent the
`actual touch positions.
`In a multi-touch sensor, a mutual capacitance measurement
`may be used to detect simultaneous touches by one or more
`objects. In the X-Y grid touch sensor, for example, mutual
`capacitance may refer to the capacitive coupling between an
`X-axis and Y-axis electrode. One set of electrodes on the
`touch screen may serve as receivers and the electrodes in the
`other set may serve as transmitters. The driven signal on the
`transmitter electrode may alter the capacitive measurement
`taken on the receiver electrode because the two electrodes are
`coupled through the mutual capacitance. In this manner, the
`mutual capacitance measurement may not encounter the
`ambiguity problems associated with self capacitance, as
`mutual capacitance can effectively address every X-Y proX
`imity relationship (node) on the touch sensor.
`More specifically, a multi-touch controller using mutual
`capacitance measurement may select one electrode in a first
`set of electrodes to be the receiver. The controller may then
`measure (one by one) the mutual capacitance for each trans
`mitter electrode in a second set of electrodes. The controller
`may repeat this process until each of the first set of electrodes
`has been selected as the receiver. The position of one or more
`touches may be determined by those mutual capacitance
`nodes experiencing the most significant capacitance change.
`These advantages of mutual capacitance over self capaci
`tance come at a cost. Specifically, mutual capacitance can
`degrade the time it takes the system to respond to a touch
`action when compared to self capacitance measurements.
`This degradation may occur because mutual capacitance is
`measured at each node, whereas self capacitance is measured
`at each electrode. In the 16x16 grid touch sensor, for example,
`a mutual capacitance measurement is taken at 256 nodes,
`whereas only 32 electrodes are measured for self capacitance.
`As a result of this tradeoff, self capacitance measurements
`are typically employed in applications that do not require
`multi-touch capabilities, and mutual capacitance measure
`ments are employed in applications that do require multi
`touch capabilities. Even so, measuring every node for mutual
`capacitance can take a significant amount of time that may
`adversely affect the multi-touch system's response to a touch
`action.
`
`SUMMARY
`
`In accordance with one embodiment of the present disclo
`Sure, a method for determining multiple touch events in a
`multi-touch sensor system is provided. The system may have
`a touch sensor including a plurality of nodes defined by a
`plurality of electrodes. The method may include performing
`self capacitance measurements for at least two of the plurality
`of electrodes, and detecting one or more touched electrodes as
`a result of the performed self capacitance measurements. The
`method may further include performing a plurality of mutual
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`3
`capacitance measurements for only a Subset of the nodes,
`wherein the subset may be fewer than all of the nodes and may
`include at least the nodes corresponding to the touched elec
`trodes. The method may additionally include detecting two or
`more touched nodes as a result of the plurality of mutual
`capacitance measurements.
`In one embodiment of the method, the plurality of elec
`trodes may comprise a first set of electrodes and a second set
`of electrodes. In this embodiment, the self capacitance mea
`Surements may be performed on each of the electrodes, and
`the touched electrodes may comprise electrodes from both
`the first set of electrodes and the second set of electrodes. In
`accordance with an alternative embodiment of the method,
`the plurality of electrodes may comprise a first set of elec
`trodes and a second set of electrodes, and the self capacitance
`measurements may be performed on each of the electrodes in
`the first set of electrodes and not on the electrodes in the
`second set of electrodes. In this alternative embodiment, the
`touched electrodes may comprise electrodes from only the
`first set of electrodes.
`In accordance with another embodiment of the present
`disclosure, a system for detecting one or more touch events on
`a touch sensor is provided. The system may comprise a touch
`sensor that may have a plurality of nodes defined by a plural
`ity of electrodes. The system may further comprise a self
`capacitance measuring means for measuring the self capaci
`tance of each of the plurality of electrodes. Additionally, the
`system may comprise mutual capacitance measuring means
`for measuring the mutual capacitance at only a Subset of the
`nodes, wherein the subset may be fewer than all of the nodes
`and may be determined based on an output of the self capaci
`tance measuring means. The System may also comprise a
`means for detecting, based on the output of the self capaci
`tance measuring means and an output of the mutual capaci
`tance measuring means, two or more touched nodes.
`In accordance with a further embodiment of the present
`disclosure, a system for detecting one or more touch events on
`a touch sensor is provided. The system may comprise a touch
`sensor that may have a plurality of nodes defined by a plural
`ity of electrodes. The system may further comprise a touch
`controller that may have a self capacitance measuring means
`for measuring the self capacitance of each of the plurality of
`electrodes, and a mutual capacitance measuring means for
`measuring the mutual capacitance of each of the plurality of
`nodes. The touch controller may be operable to perform,
`45
`using the self capacitance measuring means, self capacitance
`measurements for at least two of the plurality of electrodes.
`The touch controller may be further operable to detect one or
`more touched electrodes as a result of the performed self
`capacitance measurements. Additionally, the touch controller
`may be operable to perform, using the mutual capacitance
`measuring means, a plurality of mutual capacitance measure
`ments for only a subset of the nodes, wherein the subset may
`be fewer than all of the nodes and may include at least the
`nodes corresponding to the touched electrodes. The touch
`controller may additionally be operable to detect two or more
`touched nodes as a result of the plurality of mutual capaci
`tance measurementS.
`In one embodiment of the aforementioned system, the
`plurality of electrodes may comprise a first set of electrodes
`and a second set of electrodes, and the touch controller may
`perform the self capacitance measurements on each of the
`electrodes. According to this embodiment, the touched elec
`trodes may comprise electrodes from both the first set of
`electrodes and the second set of electrodes. In an alternative
`embodiment, which may similarly comprise a first set of
`electrodes and a second set of electrodes, the touch controller
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`US 8,933,907 B2
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`may perform the self capacitance measurements on each of
`the electrodes in the first set of electrodes and not on the
`electrodes in the second set of electrodes. In this alternative
`embodiment, the touched electrodes may comprise elec
`trodes from only the first set of electrodes.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`A more complete understanding of the present embodi
`ments and advantages thereofmay be acquired by referring to
`the following description in conjunction with the accompa
`nying drawings, in which like reference numbers indicate like
`features, and wherein:
`FIG. 1 illustrates a block diagram of an example touch
`sensor System for detecting multiple touches on a touchsen
`Sor, in accordance with the present disclosure.
`FIG. 2 illustrates a top view of an example touch sensor for
`detecting multiple touches, in accordance with the present
`disclosure.
`FIG. 2a illustrates a top view of an example touch sensor
`for detecting multiple touches, in accordance with the present
`disclosure.
`FIG.2b illustrates a top view of an example touch sensor
`for detecting multiple touches, in accordance with the present
`disclosure.
`FIG. 3 illustrates a partial cross-section, front elevation
`view of an example touch sensor, in accordance with the
`present disclosure.
`FIG. 4 illustrates electrical circuits corresponding to an
`example touch sensor in a touch sensor System, in accordance
`with the present disclosure.
`FIG. 5 illustrates electrical circuits corresponding to an
`example touch sensor in a touch sensor System, in accordance
`with the present disclosure.
`FIG. 6 illustrates an example relaxation oscillator circuit in
`a relaxation oscillator-based touch sensor system, in accor
`dance with the present disclosure.
`FIG. 7 illustrates an example timing diagram for a relax
`ation oscillator circuit output in a relaxation oscillator-based
`touch sensor system, in accordance with the present disclo
`SUC.
`FIG. 8 illustrates an example timing diagram for a relax
`ation oscillator circuit output in a relaxation oscillator-based
`touch sensor system, in accordance with the present disclo
`SUC.
`FIG. 9 illustrates an example touch controller in a relax
`ation oscillator-based touch sensor System, in accordance
`with the present disclosure.
`FIG. 10 illustrates an example touch controller in a relax
`ation oscillator-based touch sensor System, in accordance
`with the present disclosure.
`FIG. 11 illustrates example timing diagrams for a relax
`ation oscillator circuit output and a pulse drive circuit output
`in a relaxation oscillator-based touch sensor System, in accor
`dance with the present disclosure.
`FIG.11a illustrates example timing diagrams for a relax
`ation oscillator circuit output and a pulse drive circuit output
`in a relaxation oscillator-based touch sensor System, in accor
`dance with the present disclosure.
`FIG.11b illustrates an example timing diagram for a relax
`ation oscillator circuit output and a pulse drive circuit output
`in a relaxation oscillator-based touch sensor System, in accor
`dance with the present disclosure.
`FIG. 12 illustrates an example charge time measurement
`circuit in a charge time-to-voltage-based touch sensor sys
`tem, in accordance with the present disclosure.
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`DELL EXHIBIT 1031 PAGE 29
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`US 8,933,907 B2
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`FIG. 13 illustrates an example touch controller in a charge
`time-to-voltage-based touch sensor System, in accordance
`with the present disclosure.
`FIG. 14 illustrates a flow chart of an example method for
`detecting a touch on a touch sensor in a touch sensor System,
`in accordance with the present disclosure.
`FIG. 14a illustrates a flow chart of an example method for
`detecting a touch on a touch sensor in a touch sensor System,
`in accordance with the present disclosure.
`FIG. 15 illustrates a flow chart of an example method for
`detecting one or more simultaneous touches on a touch sensor
`in a touch sensor system, in accordance with the present
`disclosure.
`FIG. 15a illustrates a flow chart of an example method for
`detecting one or more simultaneous touches on a touch sensor
`in a touch sensor system, in accordance with the present
`disclosure.
`FIG. 16 illustrates a flow chart of an example method for
`detecting one or more simultaneous touches on a touch sensor
`in a touch sensor system, in accordance with the present
`disclosure.
`FIG. 16a illustrates a flow chart of an example method for
`detecting one or more simultaneous touches on a touch sensor
`in a touch sensor system, in accordance with the present
`disclosure.
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`FIG. 17 illustrates an example touch controller in a com
`bined relaxation oscillator-based and charge time-to-voltage
`based touch sensor System, in accordance with the present
`disclosure.
`FIG. 18 illustrates a flow chart of an example method for
`detecting one or more simultaneous touches on a touch sensor
`in a touch sensor system, in accordance with the present
`disclosure.
`FIG. 19 illustrates a flow chart of an example method for
`detecting one or more simultaneous touches on a touch sensor
`in a touch sensor system, in accordance with the present
`disclosure.
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`contacted by an object or that is in close proximity with an
`object. Likewise, use of the term “contact.” “contacts.” and
`any and every derivation thereof, as it relates to an object
`contacting a touch screen, should be understood to mean
`actual direct contact as well as a proximity event or a “near
`touch.”
`According to one embodiment, a multi-touch sensor sys
`tem may first perform self capacitance measurements on each
`X-axis and Y-axis electrode in a capacitive touch sensor. If a
`touch is detected on any of the electrodes, the system may
`then perform mutual capacitance measurements on only the
`nodes corresponding to the touched X-axis and Y-axis elec
`trodes or an expanded Subset of the total sensor nodes. In the
`latter case, for example, it may be desirable to performing
`mutual capacitance measurements on a Subset of nodes that
`are adjacent to the nodes corresponding to the touched X-axis
`and Y-axis electrodes. An implementation as described in
`these embodiments can reduce the measurement time, which
`may improve the touch system's response time to multi-touch
`eVentS.
`According to this embodiment, a 16x16 grid touch sensor
`may be contacted by two objects at position (1.5) and position
`(4,10). The multi-touch system may perform 32 self capaci
`tance measurements (one at each electrode) and determine
`that X-axis electrodes 1 and 4 have been touched and that
`Y-axis electrodes 5 and 10 have been touched. If the system
`Supports a maximum of two simultaneous touches, the system
`may take as few as one or as many as four mutual capacitance
`measurements to determine the actual touch positions. For
`example, if the first mutual capacitance measurement is taken
`at node (1.5), the system will detect a touch at that position
`and can conclude, by process of elimination, that the second
`touch occurred at node (4,10). If the first mutual capacitance
`measurement is taken at node (1,10), the system may con
`clude, by process of elimination, that the two touches
`occurred at positions (1.5) and (4,10). Alternatively, the sys
`tem may take mutual capacitance measurements at each of
`two, three, or four of the nodes before determining that the
`touch events occurred at positions (1.5) and (4,10). In any of
`these cases, the number of total measurements taken is less
`than the 256 measurements required in a full mutual capaci
`tance system, thus providing for better system response time.
`If the above-described system supports a maximum of 3
`simultaneous touches, the system may take as few as three or
`as many as four mutual capacitance measurements to deter
`mine that positions (1.5) and (4,10) have been touched. For
`example, after measuring (1.5) and (1,10), the system may
`still measure at least one of (4.5) and (4,10) to determine
`whether just one or both positions were touched (i.e., indicat
`ing a double or triple touch, respectively). Alternatively, the
`system Supporting three simultaneous touch events may take
`mutual capacitance measurements at each of the four nodes
`before determining that the touch events occurred at positions
`(1.5) and (4,10). In any of these cases, the number of total
`measurements taken is less than the 256 measurements
`required in a full mutual capacitance system, thus providing
`for better system response time.
`According to another embodiment, a multi-touch sensor
`system may first perform self capacitance measurements on
`one axis of a capacitive touch sensor (e.g., the X-axis). If a
`touch is detected on any of the electrodes, the system may
`then perform mutual capacitance measurements on each node
`formed by the touched electrode and each of the electrodes in
`the other axis (e.g., the Y-axis). According to this embodi
`ment, the number of total measurements taken is less than the
`256 measurements required in a full mutual capacitance sys
`tem, thus providing for better system response time.
`
`DETAILED DESCRIPTION
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`Preferred embodiments and their advantages over the prior
`art are best understood by reference to FIGS. 1-19 below,
`wherein like numbers are used to indicate like and corre
`sponding parts.
`One or more aspects of the present disclosure may com
`45
`prise a computer program that embodies the functions
`described and illustrated herein. However, it should be appar
`ent that there could be many different ways of implementing
`the present disclosure in computer programming, and the
`present disclosure should not be construed as limited to any
`one set of computer program instructions. Further, a skilled
`programmer would be able to write such a computer program
`to implement an embodiment of the present disclosure based
`on the appended flow charts and associated description in the
`application text. Therefore, disclosure of a particular set of
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`program code instructions is not considered necessary for an
`adequate understanding of how to make and use the systems
`and methods disclosed herein.
`As used herein, the terms “touch.” “touches, and any and
`every derivation thereof, as it relates to contact with a touch
`sensor, should be understood to mean an actual touch (i.e., a
`finger or object making direct contact with the touch sensor)
`as well as a proximity event or a “near touch' (i.e., a finger or
`object being placed in close proximity to the touch screen
`without actually making direct contact with the touchscreen).
`Accordingly, a “touched node,” a “touched electrode' or
`similar term is a node, electrode, etc. that has been directly
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`FIG. 1 illustrates a block diagram of an example touch
`sensor system 100 for detecting multiple touches on a touch
`sensor, in accordance with the present disclosure. As depicted
`in FIG. 1, system 100 may comprise touch sensor 200, touch
`controller 400, and host 800.
`Touch sensor 200 may generally be operable to receive
`input via contact with a human finger or other hand held
`object (e.g., Stylus, credit card, etc.). In general, touch sensor
`200 is configured to recognize a touch event through a change
`in capacitance that results from the touch event. Touch sensor
`200 may include one or more conductive elements that
`present a natural capacitance to a ground (or virtual ground)
`plane and to each other within touch sensor 200. Touch sensor
`200 may be of a semi-transparent construction, allowing it to
`be placed in front of or integrated into a graphic (video)
`display system. Alternatively, touch sensor 200 may be of an
`opaque construction (e.g., touch pad used in many current
`laptop computers). A more detailed description of an example
`touch sensor 200 according to the present disclosure is pro
`vided in the discussion of FIGS. 2-5 below.
`Touch controller 400 may generally be an electronic sys
`tem operable to dete