(12) United States Patent
`Hotelling et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 7,920,129 B2
`Apr. 5, 2011
`
`US007920129B2
`
`(54) DOUBLE-SIDED TOUCH-SENSITIVE PANEL
`WITH SHIELD AND DRIVE COMBINED
`LAYER
`
`(75) Inventors: Steve Porter Hotelling, San Jose, CA
`(US); Brian Richards Land, Redwood
`City, CA (U S)
`
`(73) Assignee: Apple Inc., Cupertino, CA (US)
`
`CN
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 1116 days.
`
`(21) App1_ NO_; 11/650,182
`
`(22) F1led:
`
`Jan. 3, 2007
`
`(65)
`
`Prior Publication Data
`US 2008/0158183 A1
`Jul. 3, 2008
`
`(51) Int. Cl.
`G09G 5/00
`(52) U-s- Cl
`
`(2006.01)
`345/173; 345/174; 345/179; 178/1801;
`178/1 8-09
`(58) Field of Classi?cation Search ........ .. 345/ 173*179,
`345/l56il62; 178/18.01*18.07, 19.01*19.06,
`178/20.01*20_04
`See application ?le for complete Search history,
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`5,483,261 A
`1/1996 Yasutake
`5,488,204 A
`1/1996 Mead et a1.
`5,825,352 A 10/1998 Bisset et a1.
`5,835,079 A 11/1998 Shieh
`5,869,791 A *
`2/1999 Young ...................... .. 178/20.01
`
`,
`
`,
`
`g 2 *
`6,188,391 B1
`6,310,610 B1
`6,323,846 B1
`6,690,387 B2
`
`178/18 01
`
`.
`
`.............. ..
`
`en et a .
`
`(Ai?lespie it a1~
`2/2001 Seely et a1‘
`10/2001 Beaton et a1.
`11/2001 Westerman et a1.
`2/2004 Zimmerman et al.
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`1754141 A
`3/2006
`
`(Commued)
`OTHER PUBLICATIONS
`
`Lee, SK. et a1. (Apr. 1985). “A Multi-Touch Three Dimensional
`Touch-Sensitive Tablet,” Proceedings of CHI.‘ ACM Conference on
`Human Factors in Computing Systems, pp. 21-25.
`(Continued)
`
`Primary Examiner * Quan-Zhen Wang
`Assistant Examiner * Jennifer T Nguyen
`(74) Attorney, Agent, or Firm * Morrison & Foerster LLP
`
`ABSTRACT
`(57)
`A multi-touch capacitive touch sensor panel can be created
`using a substrate With column and roW traces formed on either
`side of the substrate. To shield the column (sense) traces from
`the effects of capacitive coupling from a modulated Vcom
`layer in an adjacent liquid crystal display (LCD) or any source
`of capacitive coupling, the roW traces can be Widened to
`shield the column traces, and the roW traces can be placed
`closer to the LCD. In particular, the roWs can be Widened so
`that there is spacing of about 30 microns betWeen adjacent
`roW traces. In this manner, the roW traces can serve the dual
`functions of driving the touch sensor panel, and also the
`function of shielding the more sensitive column (sense) traces
`from the effects of capacitive coupling.
`
`29 Claims, 7 Drawing Sheets
`
`Substrate
`700
`
`How
`708
`
`TPK 2005
`Wintek v. TPK Touch Solutions
`IPR2013-00567
`
`

`
`US 7,920,129 B2
`Page 2
`
`US. PATENT DOCUMENTS
`Mulligan et al.
`6,970,160 B2 11/2005
`Morohoshi
`7,015,894 B2
`3/2006
`Zimmerman et al.
`7,184,064 B2
`2/2007
`7,382,139 B2* 6/2008
`Mackey ...................... .. 324/660
`7,511,702 B2* 3/2009
`Hotelling
`. 345/173
`7,532,205 B2* 5/2009
`Gillespie eta .
`............ .. 345/173
`Hotelling et al.
`7,663,607 B2
`2/2010
`2003/0231168 A1* 12/2003
`Bell et al. .................... .. 345/173
`Hotelling et al.
`2006/0026521 A1
`2/2006
`2006/0084852 A1
`4/2006
`Mason et al.
`2006/0092142 A1* 5/2006
`Gillespie et al. ............ .. 345/173
`Hotelling et al.
`2006/0097991 A1
`5/2006
`Hotelling
`2006/0197753 A1
`9/2006
`2008/0088595 A1
`4/2008
`Liu et al.
`
`OTHER PUBLICATIONS
`
`Rubine, D.H. (Dec. 1991). “The Automatic Recognition of Ges
`tures,” CMU-CS-91-202, Submitted in Partial Ful?llment of the
`Requirements of the Degree of Doctor of Philosophy in Computer
`Science at Carnegie Mellon University, 285 pages.
`Rubine, D.H. (May 1992). “Combining Gestures and Direct Manipu
`lation,” CHI ’92, pp. 659-660.
`Westerman, W. (Spring 1999). “Hand Tracking, Finger Identi?ca
`tion, and Chordic Manipulation on a Multi-Touch Surface,” A Dis
`sertation Submitted to the Faculty of the University of Delaware in
`Partial Ful?llment of the Requirements for the Degree of Doctor of
`Philosophy in Electrical Engineering, 364 pages.
`
`JP
`JP
`
`FOREIGN PATENT DOCUMENTS
`6/2000
`2000-163031 A
`11/2002
`2002-342033 A
`
`* cited by examiner
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 1 of7
`
`US 7,920,129 B2
`
`Display
`-
`Devrce
`130
`
`ll
`
`'
`Host
`; Processor
`
`128
`t
`
`l
`
`Program
`Storage
`132
`
`100
`\
`
`-
`Perrpherals
`104
`/
`
`I
`
`rvrr Panel
`Processor
`
`s
`-
`
`102
`t
`
`I
`
`.
`Multr-touch subsystem 106
`RAM
`‘)2
`
`1
`
`‘
`
`channel
`analog
`scan
`channels
`->
`» logrc ~>
`110
`|
`
`108
`1
`
`_
`
`Drrver
`Logrc
`
`114
`
`subsystem
`
`MT
`Outputs
`116
`
`_
`
`Hrgh
`Voltage
`‘ Driver
`118
`
`High
`Voltage
`Outputs Decoder
`134
`
`Driver
`
`120
`
`MT Panel 122
`Row lnputs
`
`/
`control
`slq?als
`
`Multi-touch panel
`124
`
`*{Csig
`
`126
`
`Fig. 1
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 2 017
`
`US 7,920,129 B2
`
`mma
`wml
`191% v
`WWI.
`
`C
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`mm \
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`
`to analog channels
`Fig. 2a
`
`204
`
`202
`
`Fig. 2b
`
`dielectric“> III I
`
`I
`
`I \H'”
`
`/ T Csig
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`'Q'ACsig
`due to
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`Fig. 2c
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 3 017
`
`US 7,920,129 B2
`
`Glass
`302
`
`Dielectric
`310
`
`Glass
`Row ITO 306
`208 / I
`
`300\
`
`Flex Circuit
`Portion
`314
`Flex Circuit
`Portion
`
`Fig. 3
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 4 017
`
`US 7,920,129 B2
`
`Transparent
`Adhesive
`
`Column Trace
`404
`{
`ll/lI/I /////////i-/COVer408
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`Portion
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`504/
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`‘Metal
`Traces
`
`410
`
`Flex Circuit
`Portion
`606
`
`Flex Circuit
`600
`Flex Circuit
`Portion
`
`_
`
`_
`
`Flex
`gircuit
`ortion
`514
`
`:‘
`Connfecgor Area
`
`Flg. 5
`
`Circuit Area
`602
`Flex Circuit
`P062550"
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 5 017
`
`US 7,920,129 B2
`
`702
`
`Substrate
`
`— ROW
`
`Fig. 7
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 6 017
`
`US 7,920,129 B2
`
`Rows Columns
`836
`838
`r/ \l// 1,11 I/IIIA/COVBr8OZ
`
`Panel
`800 \g KEY}; ‘\Q' m Capacitive coupling from
`/Vc0m layer 834
`§‘\\ \\\\\\ \\\\l\ LCD 804
`LCD 804
`fPolarizer 806
`)
`/lqp Class 808
`sLiquid Crystal Cell 810
`\Bottom Glass 812
`\Polarizer 814
`Backlrghl 816
`Top Glass 808
`Color Filters 808
`Vcom Layer 822
`Liquid Crystals 826
`TFT Layer 830
`
`(
`\
`'
`
`Planarization
`Layer
`820
`Polyamide
`824
`Bottom
`Glass
`812
`
`-
`
`Flg- 8
`
`Columns
`
`938 /// 900
`
`Fig. 9
`
`

`
`US. Patent
`
`Apr. 5, 2011
`
`Sheet 7 017
`
`US 7,920,129 B2
`
`MT
`Panel
`1%
`
`Mobile/ ‘
`Telephone
`k
`“36
`Flex Circuit
`1134
`Fig. 1021
`
`Digital/
`Audio/ Video
`Player
`1138
`
`Fig. 10b
`
`

`
`US 7,920,129 B2
`
`1
`DOUBLE-SIDED TOUCH-SENSITIVE PANEL
`WITH SHIELD AND DRIVE COMBINED
`LAYER
`
`FIELD OF THE INVENTION
`
`This invention relates to touch sensor panels, and more
`particularly, to capacitive multi-touch sensor panels having
`roWs and columns formed on either sides of the same sub
`strate.
`
`BACKGROUND OF THE INVENTION
`
`Many types of input devices are presently available for
`performing operations in a computing system, such as buttons
`or keys, mice, trackballs, touch panels, joysticks, touch
`screens and the like. Touch screens, in particular, are becom
`ing increasingly popular because of their ease and versatility
`of operation as Well as their declining price. Touch screens
`can include a touch panel, Which can be a clear panel With a
`touch-sensitive surface. The touch panel can be positioned in
`front of a display screen so that the touch-sensitive surface
`covers the vieWable area of the display screen. Touch screens
`can alloW a user to make selections and move a cursor by
`simply touching the display screen via a ?nger or stylus. In
`general, the touch screen can recogniZe the touch and position
`of the touch on the display screen, and the computing system
`can interpret the touch and thereafter perform an action based
`on the touch event.
`Touch panels can include an array of touch sensors capable
`of detecting touch events (the touching of ?ngers or other
`objects upon a touch-sensitive surface). Future panels may be
`able to detect multiple touches (the touching of ?ngers or
`other objects upon a touch-sensitive surface at distinct loca
`tions at about the same time) and near touches (?ngers or
`other objects Within the near-?eld detection capabilities of
`their touch sensors), and identify and track their locations.
`Examples of multi-touch panels are described in Applicant’s
`co-pending U.S. application Ser. No. 10/842,862 entitled
`“Multipoint Touchscreen,” ?led on May 6, 2004 and pub
`lished as U.S. Published Application No. 2006/0097991 on
`May 11, 2006, the contents of Which are incorporated by
`reference herein.
`Capacitive touch sensor panels can be formed from roWs
`and columns of traces on opposite sides of a dielectric. At the
`“intersections” of the traces, Where the traces pass above and
`beloW each other (but do not make direct electrical contact
`With each other), the traces essentially form tWo electrodes.
`Conventional touch panels for use over display devices have
`typically utiliZed a top layer of glass upon Which transparent
`column traces of indium tin oxide (ITO) or antimony tin oxide
`(ATO) have been etched, and a bottom layer of glass upon
`Which roW traces of ITO have been etched. HoWever, the use
`of transparent traces is not required if the conductors are thin
`enough (on the order of 30 microns). In addition, if panel
`transparency is not required (e. g. the touch panel is not being
`used over a display device), the conductors can be made out of
`an opaque material such as copper. The top and bottom glass
`layers are separated by a clear polymer spacer that acts as a
`dielectric betWeen the roW and column traces. The traces on
`both the top and bottom glass layers can have a spacing of
`about 5 mm.
`To scan a sensor panel, a stimulus canbe applied to one roW
`With all other roWs held at DC voltage levels. When a roW is
`stimulated, a modulated output signal can be capacitively
`coupled onto the columns of the sensor panel. The columns
`can be connected to analog channels (also referred to herein
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`as event detection and demodulation circuits). For every roW
`that is stimulated, each analog channel connected to a column
`generates an output value representative of an amount of
`change in the modulated output signal due to a touch or hover
`event occurring at the sensor located at the intersection of the
`stimulated roW and the connected column. After analog chan
`nel output values are obtained for every column in the sensor
`panel, a neW roW is stimulated (With all other roWs once again
`held at DC voltage levels), and additional analog channel
`output values are obtained. When all roWs have been stimu
`lated and analog channel output values have been obtained,
`the sensor panel is said to have been “scanned,” and a com
`plete “image” of touch or hover can be obtained over the
`entire sensor panel. This image of touch or hover can include
`an analog channel output value for every pixel (roW and
`column) in the panel, each output value representative of the
`amount of touch or hover that Was detected at that particular
`location.
`Because the roWs must be either stimulated With an AC
`signal or held at a DC voltage level, and because the columns
`must be connected to analog channels so that modulated
`output signals can be detected, demodulated and converted to
`output values, electrical connections must be formed With the
`roWs and columns on either side of the dielectric of the sensor
`panel. Because the roWs and columns are perpendicular to
`each other, the most straightforward Way to connect to these
`roWs and columns is to bond a ?ex circuit at one edge of the
`sensor panel (eg the shorter side of a rectangular panel) to
`provide connections to the columns, and bond another ?ex
`circuit on an adjacent edge of the sensor panel (eg the longer
`side of a rectangular panel) to provide connections to the
`roWs. HoWever, because these ?ex circuit connections areas
`are not on the same edge of the sensor panel and are not on
`directly opposing sides of the dielectric, the sensor panel must
`be made larger to accommodate these tWo non-overlapping
`connection areas.
`Furthermore, When a transparent capacitive touch sensor
`panel is bonded to a liquid crystal display (LCD), a modulated
`Vcom layer in the LCD can couple onto the columns of the
`sensor panel, causing noise to appear on the columns.
`
`SUMMARY OF THE INVENTION
`
`A multi-touch sensorpanel can be created using a substrate
`With column and roW traces formed on either side of the
`substrate using a novel fabrication process. Flex circuits can
`be used to connect the column and roW traces on either side of
`the sensor panel to its associated sensor panel circuitry.
`Traces made of copper or other highly conductive metals
`running along the edge of the substrate can be used to bring
`the roW traces to the same edge of the substrate as the column
`traces so that the ?ex circuits can be bonded to the same edge
`of the substrate on directly opposing sides of the substrate,
`minimiZing the area needed for connectivity and reducing the
`overall siZe of the sensor panel. A single ?ex circuit can be
`fabricated to connect to the roWs and columns on directly
`opposing sides at the same edge of the substrate. Further
`more, the roW traces can be Widened to shield the column
`traces from a modulated Vcom layer.
`Column and roW ITO traces can be formed on both sides of
`a DITO substrate using several fabrication methods. In one
`embodiment, a substrate can be placed on the rollers of the
`fabrication machinery and a layer of ITO can be sputtered
`onto a ?rst side of the DITO substrate and etched (eg using
`photolithography techniques) to form the column traces. A
`protective coating of photoresist (e.g. tWo layers of photore
`sist) can then be applied over the column traces, and the DITO
`
`

`
`US 7,920,129 B2
`
`3
`substrate can be ?ipped over so that the rollers make contact
`only With the applied photoresist on the ?rst side and not the
`formed column traces. Another layer of ITO can then be
`sputtered onto the noW-exposed back side of the DITO sub
`strate and etched to form roW traces 508.
`If no metal traces are required, the photoresist on the ?rst
`side can be stripped off to complete the process. However, if
`metal traces are required at the edges to connect to the roW
`traces and bring them to a particular edge of the substrate, a
`protective coating of photoresist (e. g. tWo layers of photore
`sist) can be applied over the roW traces, leaving the edges
`exposed. A metal layer can then be sputtered over the photo
`resist and exposed edges, and the metal layer can then be
`etched to form metal traces at the edges. Finally, all remaining
`layers of photoresist can be stripped off.
`Flex circuit portions on a single ?ex circuit can be formed
`for connecting to the roW and column traces, respectively, on
`either side of a DITO substrate, and to a host processor. The
`?ex circuit can also include a circuit area upon Which a
`multi-touch subsystem, multi-touch panel processor, high
`voltage driver and decoder circuitry, an EEPROM and some
`essential small components such as bypass capacitors can be
`mounted and connected to save space.
`The roWs of the DITO substrate can also be Widened for
`shielding purposes and for providing a uniform appearance
`according to embodiments of this invention. To prevent the
`capacitive coupling of a modulated Vcom layer onto the col
`umns of the substrate, the roWs may be Widened. The number
`of roWs does not change, but they can be much Wider, leaving
`only about 30 microns of space betWeen them. Because these
`Wider roWs are not isolated but are instead either held at a DC
`voltage or stimulated With a stimulation voltage, these Wider
`roWs act as a shield, preventing a modulatedVcom layer from
`capacitively coupling onto the columns. In addition, because
`of the narroW spacing betWeen them, the Wide roWs provide a
`uniform appearance. Thus, shielding, modulation and a uni
`form appearance can be obtained from a single layer of ITO.
`
`20
`
`25
`
`30
`
`35
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`40
`
`FIG. 1 illustrates an exemplary computing system operable
`With a capacitive multi-touch sensor panel according to one
`embodiment of this invention.
`FIG. 2a illustrates an exemplary capacitive multi-touch
`panel according to one embodiment of this invention.
`FIG. 2b is a side vieW of exemplary pixel in a steady-state
`(no-touch) condition according to one embodiment of this
`invention.
`FIG. 20 is a side vieW of exemplary pixel in a dynamic
`(touch) condition according to one embodiment of this inven
`tion.
`FIG. 3 is an exploded perspective vieW of an exemplary
`capacitive touch sensor panel formed from a top layer of glass
`upon Which transparent column traces of ITO have been
`etched, and a bottom layer of glass upon Which roW traces of
`ITO have been etched.
`FIG. 4 illustrates an exemplary capacitive touch sensor
`panel fabricated using a double-sided ITO (DITO) substrate
`having column and roW ITO traces formed on either side of
`the substrate, and bonded betWeen a cover and an LCD using
`transparent adhesive according to one embodiment of this
`invention.
`FIG. 5 is an exploded perspective vieW of an exemplary
`DITO substrate (With its thickness greatly exaggerated for
`purposes of illustration only) With columns and roWs formed
`on either side according to one embodiment of this invention.
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`FIG. 6 illustrates an exemplary ?ex circuit according to one
`embodiment of this invention, including ?ex circuit portions
`for connecting to the roW and column traces, respectively, on
`either side of a DITO substrate, and a ?ex circuit portion for
`connecting to a host processor.
`FIG. 7 is an exploded perspective vieW of an exemplary
`DITO substrate (With its thickness greatly exaggerated for
`purposes of illustration only) With columns and roWs formed
`on either side, and small isolated squares betWeen the col
`umns and roWs to provide a uniform appearance.
`FIG. 8 illustrates a stackup of an exemplary double-sided
`touch panel along With a cover and liquid crystal display
`(LCD) according to one embodiment of this invention.
`FIG. 9 is a perspective vieW of an exemplary DITO sub
`strate (With its thickness greatly exaggerated for purposes of
`illustration only) illustrating the Widening of roWs for shield
`ing purposes and for providing a uniform appearance accord
`ing to one embodiment of this invention.
`FIG. 10a illustrates an exemplary mobile telephone that
`can include the capacitive touch sensor panel and a ?ex circuit
`capable of connecting to both sides of the substrate according
`to one embodiment of this invention.
`FIG. 10b illustrates an exemplary digital audio player that
`can include the capacitive touch sensor panel and a ?ex circuit
`capable of connecting to both sides of the substrate according
`to one embodiment of this invention.
`
`DETAILED DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`In the folloWing description of preferred embodiments,
`reference is made to the accompanying drawings Which form
`a part hereof, and in Which it is shoWn by Way of illustration
`speci?c embodiments in Which the invention may be prac
`ticed. It is to be understood that other embodiments may be
`utiliZed and structural changes may be made Without depart
`ing from the scope of the preferred embodiments of the
`present invention.
`Multi-touch sensor panels and their associated sensor
`panel circuitry may be able to detect multiple touches (touch
`events or contact points) that occur at about the same time,
`and identify and track their locations. FIG. 1 illustrates exem
`plary computing system 100 operable With capacitive multi
`touch sensor panel 124 according to embodiments of this
`invention. Multi-touch sensor panel 124 can be created using
`a substrate With column and roW traces formed on either side
`of the substrate using a novel fabrication process. Flex cir
`cuits can be used to connect the column and roW traces on
`either side of the sensor panel to its associated sensor panel
`circuitry. Traces made of copper or other highly conductive
`metals running along the edge of the substrate can be used to
`bring the roW traces to the same edge of the substrate as the
`column traces so that the ?ex circuits can be bonded to the
`same edge of the substrate on directly opposing sides of the
`substrate, minimiZing the area needed for connectivity and
`reducing the overall siZe of the sensor panel. A single ?ex
`circuit can be fabricated to connect to the roWs and columns
`on directly opposing sides at the same edge of the substrate.
`Furthermore, the roW traces can be Widened to shield the
`column traces from a modulated Vcom layer.
`Computing system 100 can include one or more panel
`processors 102 and peripherals 104, and panel subsystem
`106. The one or more processors 102 can include, for
`example, an ARM968 processors or other processors With
`similar functionality and capabilities. HoWever, in other
`embodiments, the panel processor functionality can be imple
`mented instead by dedicated logic such as a state machine.
`
`

`
`US 7,920,129 B2
`
`5
`Peripherals 104 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 106 can include, but is not limited to, one
`or more analog channels 108, channel scan logic 110 and
`driver logic 114. Channel scan logic 110 can access RAM
`112, autonomously read data from the analog channels and
`provide control for the analog channels. This control can
`include multiplexing columns of multi-touch panel 124 to
`analog channels 108. In addition, channel scan logic 110 can
`control the driver logic and stimulation signals being selec
`tively applied to roWs of multi-touch panel 124. In some
`embodiments, panel subsystem 106, panel processor 102 and
`peripherals 104 can be integrated into a single application
`speci?c integrated circuit (ASIC).
`Driver logic 114 can provide multiple panel subsystem
`outputs 11 6 and can present a proprietary interface that drives
`high voltage driver, Which is comprised of decoder 120 and
`subsequent level shifter and driver stage 118, although level
`shifting functions could be performed before decoder func
`tions. Level shifter and driver 118 can provide level shifting
`from a loW voltage level (eg CMOS levels) to a higher
`voltage level, providing a better signal-to-noise (S/N) ratio
`for noise reduction purposes. Decoder 120 can decode the
`drive interface signals to one out of N outputs, Whereas N is
`the maximum number of roWs in the panel. Decoder 120 can
`be used to reduce the number of drive lines needed betWeen
`the high voltage driver and panel 124. Each panel roW input
`122 can drive one or more roWsinpanel124. In some embodi
`ments, driver 118 and decoder 120 can be integrated into a
`single ASIC. HoWever, in other embodiments driver 118 and
`decoder 120 can be integrated into driver logic 114, and in
`still other embodiments driver 118 and decoder 120 can be
`eliminated entirely.
`Computing system 100 can also include host processor 128
`for receiving outputs from panel processor 102 and perform
`ing 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 ?le
`or document, vieWing a menu, making a selection, executing
`instructions, operating a peripheral device connected to the
`host device, ansWering a telephone call, placing a telephone
`call, terminating a telephone call, changing the volume or
`audio settings, storing information related to telephone com
`munications 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 pro?le associated With a user’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 128 can
`also perform additional functions that may not be related to
`panel processing, and can be coupled to program storage 132
`and display device 130 such as a liquid crystal display (LCD)
`for providing a UI to a user of the device.
`As mentioned above, multi-touch panel 124 can in some
`embodiments include a capacitive sensing medium having a
`plurality of roW traces or driving lines and a plurality of
`column traces or sensing lines (although other sensing media
`may also be used) separated by a dielectric. In some embodi
`ments, the dielectric material can be transparent, such as
`glass, or can be formed from other materials such as Mylar.
`The roW and column traces can be formed from a transparent
`conductive medium such as ITO or ATO, although other
`transparent or non-transparent materials such as copper can
`also be used. In some embodiments, the roW and column
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`traces can be perpendicular to each other, although in other
`embodiments other non-orthogonal and non-Cartesian orien
`tations are possible. For example, in a polar coordinate sys
`tem, the sensing lines canbe concentric circles and the driving
`lines can be radially extending lines (or vice versa). It should
`be understood, therefore, that the terms “roW” and “column,”
`“?rst dimension” and “second dimension,” or “?rst axis” and
`“second axis” as may be used herein are intended to encom
`pass not only orthogonal grids, but the intersecting traces of
`other geometric con?gurations having ?rst and second
`dimensions (eg the concentric and radial lines of a polar
`coordinate arrangement).
`At the “intersections” of the traces, Where the traces pass
`above and beloW each other (but do not make direct electrical
`contact With each other), the traces essentially form tWo elec
`trodes (although more than tWo traces could intersect as Well).
`Each intersection of roW and column traces can represent a
`capacitive sensing node and can be vieWed as picture element
`(pixel) 126, Which can be particularly useful When multi
`touch panel 124 is vieWed as capturing an “image” of touch.
`(In other Words, after multi-touch subsystem 106 has deter
`mined Whether a touch event has been detected at each touch
`sensor in the multi-touch panel, the pattern of touch sensors in
`the multi-touch panel at Which a touch event occurred can be
`vieWed as an “image” of touch (eg a pattern of ?ngers
`touching the panel).) The capacitance betWeen roW and col
`umn electrodes appears as a stray capacitance on all columns
`When the given roW is held at DC and as a mutual capacitance
`Csig When the given roW is stimulated With an AC signal. The
`presence of a ?nger or other object near or on the multi-touch
`panel can be detected by measuring changes to Csig. The
`columns of multi-touch panel 124 can drive one or more
`analog channels 108 (also referred to herein as event detec
`tion and demodulation circuits) in multi-touch subsystem
`106. In some embodiments, each column is coupled to one
`dedicated analog channel 108. HoWever, in other embodi
`ments, the columns may be couplable via an analog sWitch to
`a feWer number of analog channels 108.
`FIG. 2a illustrates exemplary capacitive multi-touch panel
`200. FIG. 211 indicates the presence of a stray capacitance
`Cstray at each pixel 202 located at the intersection of a roW
`204 and a column 206 trace (although Cstray for only one
`column is illustrated in FIG. 2 for purposes of simplifying the
`?gure). Note that although FIG. 2a illustrates roWs 204 and
`columns 206 as being substantially perpendicular, they need
`not be so aligned, as described above. In the example of FIG.
`2a, AC stimulus Vstim 214 is being applied to one roW, With
`all other roWs connected to DC. The stimulus causes a charge
`to be injected into the column electrodes through mutual
`capacitance at the intersecting points. This charge is
`QsigICsigXVstm. Each of columns 206 may be selectively
`connectable to one or more analog channels (see analog chan
`nels 108 in FIG. 1).
`FIG. 2b is a side vieW of exemplary pixel 202 in a steady
`state (no-touch) condition. In FIG. 2b, an electric ?eld of
`electric ?eld lines 208 of the mutual capacitance betWeen
`column 206 and roW 204 traces or electrodes separated by
`dielectric 210 is shoWn.
`FIG. 20 is a side vieW of exemplary pixel 202 in a dynamic
`(touch) condition. In FIG. 20, ?nger 212 has been placed near
`pixel 202. Finger 212 is a loW-impedance object at signal
`frequencies, and has an AC capacitance C?nger from the
`column trace 204 to the body. The body has a self-capacitance
`to ground Cbody of about 200 pF, Where Cbody is much
`larger than C?nger. If ?nger 212 blocks some electric ?eld
`lines 208 betWeen the roW and column electrodes (those
`fringing ?elds that exit the dielectric and pass through the air
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`above the roW electrode), those electric ?eld lines are shunted
`to ground through the capacitance path inherent in the ?nger
`and the body, and as a result, the steady state signal capaci
`tance Csig is reduced by ACsig. In other Words, the combined
`body and ?nger capacitance act to reduce Csig by an amount
`ACsig (Which can also be referred to herein as Csig_sense),
`and can act as a shunt or dynamic return path to ground,
`blocking some of the electric ?elds as resulting in a reduced
`net signal capacitance. The signal capacitance at the pixel
`becomes Csig-ACsig, Where Csig represents the static (no
`touch) component and ACsig represents the dynamic (touch)
`component. Note that Csig-ACsig may alWays be nonZero
`due to the inability of a ?nger, palm or other object to block all
`electric ?elds, especially those electric ?elds that remain
`entirely Within the dielectric material. In addition, it should be
`understood that as a ?nger is pushed harder or more com
`pletely onto the multi-touch panel, the ?nger can tend to
`?atten, blocking more and more of the electric ?elds, and thus
`ACsig can be variable and representative of hoW completely
`the ?nger is pushing doWn on the panel (i.e. a range from
`“no-touch” to “full-touch”).
`Referring again to FIG. 2a, as mentioned above, Vstim
`signal 214 can be applied to a roW in multi-touch panel 200 so
`that a change in signal capacitance can be detected When a
`?nger, palm or other object is present. Vstim signal 214 can be
`generated as one or more pulse trains 216 at a particular
`frequency, With each pulse train including a number of pulses.
`Although pulse trains 216 are shoWn as square Waves, other
`Waveshapes such as sine Waves can also be employed. A
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`plurality of pulse trains 216 at different frequencies can be
`transmitted for noise reduction purposes to detect and avoid
`noisy frequencies. Vstim signal 214 essentially injects a
`charge into the roW, and can be applied to one roW of multi
`touch panel 200 at a time While all other roWs are held at a DC
`level. HoWever, in other embodiments, the multi-touch panel
`can be divided into tWo or more sections, With Vstim signal
`214 being simultaneously applied to one roW in each section
`and all other roWs in that region section held at a DC voltage.
`Each analog channel coupled to a column measures the
`mutual capacitance formed betWeen that column and the roW.
`This mutual capacitance is comprised of the signal capaci
`tance Csig and any change Csig_sense in that signal capaci
`tance due to the presence of a ?nger, palm or other body part
`or object. These column values provided by the analog chan
`nels may be provided in parallel While a single roW is being
`stimulated, or may be provided in series. If all of the values
`representing the signal capacitances for the columns have
`been obtained, another roW in multi-touch panel 200 can be
`stimulated With all others held at a DC voltage, and the col
`umn signal capacitance measurements can be repeated. Even
`tually, if Vstim has been applied to all roWs, and the signal
`capacitance values for all columns in all roWs have been
`captured (i.e. the entire multi-touch panel 200 has been
`“scanned”), a “snapshot” of all pixel values can be obtained
`for the entire multi-touch panel 200. This snap shot data can be
`initially saved in the multi-touch s