||||||||||||||l|||||||||||||||||||||l|||||lllll|l|||||||l||||||||l|l|||||||
`
`US008059015B2
`
`(12) United States Patent
`Hua et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,059,015 B2
`Nov. 15, 2011
`
`(54) CAPACITANCE SENSING MATRIX FOR
`KEYBOARD ARCHITECTURE
`
`(75)
`
`Inventors: Liu Hua, Shanghai (CN); Jiang
`XiaoPing, Shanghai (CN)
`
`(73) Assignee: Cypress Semiconductor Corporation,
`San Jose, CA (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 915 days.
`
`(21) Appl.No.: 11/440,924
`
`(22) Filed:
`
`May 25, 2006
`
`(65)
`
`Prior Publication Data
`
`US 2007/0273560 A1
`
`Nov. 29, 2007
`
`(51)
`
`Int. Cl.
`H03K 17/96
`(52) U.S.Cl.
`
`(2005.01)
`341/33,324/662; 345/173; 178/18.05;
`178/18.06
`
`(58) Field of Classification Search .................. .. 341/22,
`341/33; 345/156,168,173; 178/18.05, 18.06;
`324/658-668
`
`See application file for complete search history.
`
`(56)
`
`References Cited
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`(Continued)
`
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`
`(Continued)
`
`Primary Examiner — Timothy Edwards, Jr.
`
`(57)
`
`ABSTRACT
`
`An apparatus and method for selecting a keyboard key based
`on a position ofa presence of a conductive object on a sensing
`device and a pre-defined area of the keyboard key. The appa-
`ratus may include a sensing device and a processing device.
`The sensing device may include a plurality of sensor elements
`to detect a presence of a conductive object on the sensing
`device. Multiple keyboard keys are assigned to pre-defined
`areas ofthe sensing device. The processing device is coupled
`to the sensing device using capacitance sensing pins, and may
`be operable to determine a position of the presence of the
`conductive object, and to select a keyboard key based on the
`position ofthe conductive object and the pre-defined areas of
`the sensing device.
`
`26 Claims, 14 Drawing Sheets
`
`
`fiK¢X9X9X9X9X9X99
`
`1 ><o><o><o><o><o><o><o o
`
`
`‘ KO><O><O><¢><¢><¢><0 0
`
`) ><o><o><o><o><o><o><o «
`1 ><o><o><o><o><o><o><o o
`
`><o><o><o><o><o><o><o o
`
`CalumnM
`5050/1)
`
`EXHIBIT 10019 5"
`
`IPR Petition for U.S. Patent No. 8,059,015
`
`
`
`Column 1
`505(1)
`
`Scum,
`50](L)
`Element
`
`Tmees
`Conductive
`502
`
`Conductive
`Trace:
`50!
`
`Y
`
`X
`
`

`
`US 8,059,015 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
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`7,109,978 B2
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`7,129,935 B2
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`7,239,302 B2
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`7,301,351 B2 *
`1112007 Deangelis eta!. ............ 324/687
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`7,362,244 B2
`4/2008 Geaghan et a!.
`7,362,313 B2
`7,423,635 B2
`9/2008 Taylor et a!.
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`7,439,962 B2
`7,446,300 B2
`1112008 Montanya Silvestre
`1112008 Gillespie et a!.
`7,450,113 B2
`7,466,307 B2 *
`12/2008 Trent et al ..................... 345/173
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`112009 Jobs et a!.
`5/2009 Gillespie et a!.
`7,532,205 B2
`7,539,513 B2
`5/2009 Cathey eta!.
`212010 Bolender
`7,656,392 B2
`212010 Hotelling eta!.
`7,663,607 B2
`5/20 10 Krah et a!.
`7,710,397 B2
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`7,719,522 B2
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`7,728,377 B2
`112011 Godyak
`7,863,582 B2
`2003/0011576 A1 *
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`9/2006 Hotelling eta!.
`2007/0008299 A1 *
`112007 Hristov ......................... 345/173
`2007/0046299 A1 *
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`2007/0063876 A1 *
`3/2007 Wong .............................. 341134
`2007/0074913 A1
`4/2007 Geaghan et a!.
`
`2007/0132737 A1
`2007/0177803 A1
`2007/0229466 A1 *
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`2007/0236475 A1
`2007/0236618 A1 *
`2007/0247431 A1
`2007/0262962 A1
`2008/0007434 A1
`2008/0041640 A1
`2008/0042994 A1
`2008/0048997 A1
`2008/0084400 A1
`2008/0088602 A1
`2008/0122796 A1
`2008/0165132 A1
`2008/0165140 A1
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`2008/0165255 A1
`2008/0192005 A1
`2008/0204426 A1
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`2008/0278178 A1 *
`2008/0316183 A1
`
`6/2007 Mulligan eta!.
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`10/2007 Peng eta!. .................... 345/173
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`
`wo
`
`FOREIGN PATENT DOCUMENTS
`WO 00/02188 A1
`1/2000
`
`OTHER PUBLICATIONS
`
`"The Virtual Keyboard: I-Tech Bluetooth/Serial Virtual Laser Key(cid:173)
`board available now!", The Virtual Laser Keyboard (VKB) online
`worldwide shop, http:/ /www.virtual-laser-keyboard.com, 4 pages,
`dowloaded Apr. 13, 2006.
`"CY8C21x34 Data Sheet", Cypress Semiconductore Corporation,
`CSR User Module, CSR vl.O, Oct. 6, 2005, pp. 1-36.
`"IBM PC keyboard", Wikipedia, the free encyclopedia, 3 pages,
`http:/ /en.wikipedia.org/wiki/PC_keyboard.
`Ryan Seguine, eta!., "Layout Guidelines for PSoC™ CapSense™",
`Cypress Application Note AN2292, Revision B, Oct. 31, 2005, pp.
`1-15.
`Dennis Seguine, "Capacitive Switch Scan", Cypress Application
`Note AN2233a, Revision B, Apr. 14, 2005, pp. 1-6.
`USPTO Non-Final Rejection for U.S. Appl. No. 111395,674 dated
`Apr. 19, 2010; 15 pages.
`USPTO Non-Final Rejection for U.S. Appl. No. 111395,674 dated
`Nov. 18, 2009; 11 pages.
`USPTO Final Rejection for U.S. Appl. No. 111395,674 dated Jul. 16,
`2009; 12 pages.
`USPTO Non-Final Rejection for U.S. Appl. No. 111395,674 dated
`Feb. 10, 2009; 10 pages.
`USPTO Final Rejection for U.S. Appl. No. 111432,130 dated Jul. 19,
`20 10; 15 pages.
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`2009; 15 pages.
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`Jun. 9, 2009; 14 pages.
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`111432,130 dated Mar. 31, 2009; 6 pages.
`Chris Mack, "Semiconductor Lithography-The Basic Process,"
`Gentleman Scientist, downloaded Apr. 20, 2006, <http://www.
`lithoguru.com/scientistllithobasics.htrnl>; 12 pages.
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`Apr. 20, 2006, <http://en.wikipedia.org/wiki/Photolithography>; 3
`pages.
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`May 20, 2010; 11 pages.
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`Mar. 19, 2009; 25 pages.
`
`

`
`US 8,059,015 B2
`Page 3
`
`USPTO Requirement for Restriction/Election for U.S. Appl. No.
`11/396,179 dated Feb. 3, 2009; 6 pages.
`USPTO Non-Final Rejection for US. Appl. No. 11/395,674 dated
`Aug. 27, 2010; 15 pages.
`USPTO Advisory Action for US. Appl. No. 11/605,506 dated Apr.
`12, 2010; 3 pages.
`USPTO Final Rejection for US. Appl. No. 11/605,506 dated Feb. 3,
`2010; 14 pages.
`
`USPTO Non-Final Rejection for US. Appl. No. 11/605,506 dated
`Aug. 11, 2009; 11 pages.
`USPTO Final Rejection for US. Appl. No. 11/605,819 dated Feb. 2,
`2010; 15 pages.
`USPTO Non-Final Rejection for US. Appl. No. 11/605,819 dated
`Aug. 11, 2009; 12 pages.
`
`* cited by examiner
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 1 0114
`
`US 8,059,015 B2
`
`
`
`
`
`$50K Avvmowg SE98
`
`
`
`
`
`AwVmQFI @328 $598
`
`xi .UE
`
`3%!
`
`52:8 WT :VvE/B TT @373 MT
`
`N> F> o>
`
`m: d; :58
`
`m2
`
`:50
`
`25:8
`
`52:8
`
`
`
`M m
`
`869% mm 5875 Fm 5873 CE
`
`Aovmows
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 2 0114
`
`US 8,059,015 B2
`
`o 5:28
`
`m c5200
`
`m 55.60
`
`o zswom
`
`r =smom
`
`N 5.81
`
`n zsmmm
`
`Row 0
`
`Row 1
`
`Row 2
`
`Row 3
`
`Pattern 0
`Pattern 1
`Pattern 2
`
`Pattern 3
`
`0
`
`1
`1
`
`110
`
`Scan Results For No Key Press
`
`FIG. 1C
`
`P 5:200
`
`N 5:28
`
`M 5:28
`
`N 1 4! 4| 1
`
`258m 1 1 1 1
`
`113
`
`11 1
`
`o 55%
`
`Row 0
`
`Row 1
`
`Row 2
`
`Row 3
`
`Pattern 0
`
`Pattern 1
`
`Pattern 2
`
`Pattern 3
`
`0
`
`1
`
`1
`
`1
`
`Scan Results for Key 1,1 Pressed
`
`FIG. 1D
`
`

`
`U.S. Patent
`
`Nov. 15, 2011
`
`Sheet 3 of 14
`
`US 8,059,015 B2
`
`.om:om-:o=o
`
`ovamcezm
`
`.om:am-;o=o._.
`
`omm.%__m
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`
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`
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`
`
`
`
`
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 4 0114
`
`US 8,059,015 B2
`
`300 \
`
`Varying Switch Capacitance
`
`303
`
`20,:
`
`302
`
`p
`Adjacent Plate
`Capacitor with Shunt
`
`301
`
`FIG. 3A
`
`Capacitive Switch
`
`Fin
`
`307\
`'
`
`_
`
`304
`
`3
`>
`
`7
`
`22:23:35???
`
`Processing
`Device
`
`lllil
`
`FIG. 3B
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 5 0114
`
`US 8,059,015 B2
`
`Relaxation Osullator
`
`350
`
`353
`
`356
`
`CAP
`
`

`
`U.S. Patent
`
`1v.0N
`
`11
`
`6w.h__
`
`41
`
`US 8,059,015 B2
`
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`
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`
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`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 7 0114
`
`US 8,059,015 B2
`
`Sensor
`Element
`5010
`
`Sensor
`Element
`503(1)
`
`Row 1
`504(1)
`
`Sensor Array 51m
`
`Sensor
`Element
`503(K)
`
`Conductive
`Object
`303
`
`Row N
`504(N)
`
`Column 1
`505(1)
`
`Sensor
`Element
`501 (L)
`
`)
`Conductive
`Traces
`502
`
`<\
`Conductive
`Traces Y
`502
`
`Processing
`Device
`m
`
`Column M
`505(M)
`
`X
`
`FIG. 5A
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 8 0f 14
`
`US 8,059,015 B2
`
`Sensor Array _0
`55
`
`6
`
`.10 C 3
`
`MD m(
`UFO M)
`db3 “M
`
`Element 2 i 5
`
`Sensor
`
`501(L)"\
`
`Column 1/
`505(1)
`
`II
`I]
`Processing
`Device
`210
`
`FIG. 5B
`
`

`
`US. Patent
`
`Nov. 15 2011
`
`Sheet 9 0114
`
`US 8,059,015 B2
`
`g n "U a 0
`
`0 8 5 r e y a L
`
`FIG. 5D
`
`

`
`US. Patent
`
`NOV. 15, 2011
`
`Sheet 10 0f 14
`
`US 8,059,015 B2
`
`Column 1
`606(2)
`
`605(3)
`
`P2
`
`P3
`
`Processing Device
`P0
`&
`
`6
`605(1)
`
`8
`605(0)
`
`FIG. 6B
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 11 0114
`
`US 8,059,015 B2
`
`Sensor
`Element
`
`Sensor
`Element
`
`606(25) Sensor Matrix @
`
`
`
`
`
`SGIISOI' Element 503(1)
`
`Row 1
`504(1)
`
`Conductive
`Object
`
`Row 8
`504(8)
`
`Column 1
`505(1)
`
`Sensor
`
`Element
`501(8)
`
`) -
`Conductive
`Traces
`502
`
`Column 8
`505(8)
`
`Processing
`Device
`_'2 1 0
`
`Conductive
`Traces
`502
`
`Y
`
`X
`
`FIG. 6C
`
`

`
`US. Patent
`
`Nov. 15, 2011
`
`Sheet 12 0114
`
`US 8,059,015 B2
`
`Handheld Device
`675 \‘
`f
`
`Display
`@
`
`L
`
`/
`
`Button
`Button
`Button
`__£_)677 1 m 971(3)
`
`Height
`679 m
`
`Keyboard
`§7_8
`
`V
`
`WIdth/
`
`680
`
`FIG. 6D
`
`

`
`US. Patent
`
`NOV. 15, 2011
`
`Sheet 13 0f 14
`
`US 8,059,015 B2
`
`700 \
`
`701
`
`De?ne key-mapping
`data structure
`
`‘
`
`Measuring the columns of
`capacitance sensor matrix
`
`702
`
`Determining the x-coordinate
`position
`
`703
`
`Measuring the rows of
`capacitance sensor matrix
`
`704
`
`Determining the y-coordinate
`position
`
`1
`
`k
`
`J
`
`f
`
`w
`
`Using the x- and y
`coordinate positions to look- w 706
`up the pre-de?ned areas of
`the key-mapping data
`structure, and output the
`results of look-up
`
`FIG. 7
`
`

`
`U.S. Patent
`
`Nov. 15, 2011
`
`Sheet 14 of 14
`
`US 8,059,015 B2
`
`FIG.8
`
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`
`
`Posiion
`
`804
`
`802
`
`
`
`Y-
`
`803
`
`
`
`x-K9)!CoordinateCoordinate 801
`
`

`
`US 8,059,015 B2
`
`1
`CAPACITANCE SENSING MATRIX FOR
`KEYBOARD ARCHITECTURE
`
`TECHNICAL FIELD
`
`This invention relates to the ?eld of user interface devices
`and, in particular, to touch-sensing devices.
`
`BACKGROUND
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`a large pin count, may increase the die area of the circuit, or
`alternatively, or may decrease the robustness of the circuit by
`decreasing the possibility of additional functionality in the
`same circuit With limited pins. Also, the resistance scan
`matrix keyboards cannot be built in very small areas because
`it is limited by the pull-up resistor and mechanical button for
`each keyboard key. For example, the mechanical button of
`each keyboard key may have an area of about 0.5 centimeters
`(cm)><0.5 cm, the total keyboard area Will be at least 25.25
`cm2 for a keyboard having 101 keyboard keys (e.g., 101><0.5
`cm><0.5 cm:25.25 cm2).
`Another conventional keyboard may include a virtual key
`board. Virtual keyboards are a representation of a keyboard
`displayed on a touch screen. Tapping the “virtual keys” With
`a stylus or ?nger is the same as pressing a real key on a
`keyboard. For example, a PDA may supply keyboard func
`tionality by providing a keyboard displayed on the touch
`screen of the PDA, instead of including the mechanical key
`board keys on the assembly of the PDA. This design, hoWever,
`may take up too much precious real estate on the display.
`Another example of a conventional virtual keyboard is a
`representation of a keyboard projected onto a ?at surface such
`as a desktop. Using ?ngers as With a normal keyboard, an
`optical or electronic beam is used to pick up the tapping of the
`keyboard keys of the projected image. Such a device enables
`PDAs and other small handhelds to create a full-siZe key
`board. One example of this type of virtual keyboards is a
`virtual laser keyboard (VKB). The VKB Works by using both
`infrared and laser technology to produce an invisible circuit
`and project a full-siZe virtual QWERTY keyboard on to any
`surface. The virtual PC keyboard behaves exactly like a real
`one: direction technology based on optical recognition
`enables the user to tap the images of the keys, Which feeds into
`the compatible PDA, Smartphone, laptop or PC. QWERTY
`refers to a standard English-language typeWriter keyboard
`(sometimes called the Sholes keyboard after its inventor), as
`opposed to Dvorak, foreign-language layouts (e. g. “keyboard
`AZERTY” in French-speaking countries), a space-cadet, or
`APL keyboards.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The present invention is illustrated by Way of example, and
`not by Way of limitation, in the ?gures of the accompanying
`draWings.
`FIG. 1A illustrates a resistance matrix of a conventional
`keyboard.
`FIG. 1B illustrates a keyboard key and tWo electrical con
`tacts of the conventional resistance matrix of FIG. 1A.
`FIG. 1C illustrates scan results for no keyboard keys
`pressed on a conventional resistance scan matrix.
`FIG. 1D illustrates scan results for a keyboard key pressed
`on a conventional resistance scan matrix.
`FIG. 2 illustrates a block diagram of one embodiment of an
`electronic system having a processing device for detecting a
`presence of a conductive object.
`FIG. 3A illustrates a varying sWitch capacitance.
`FIG. 3B illustrates one embodiment of a sensing device
`coupled to a processing device.
`FIG. 3C illustrates one embodiment of a relaxation oscil
`lator.
`FIG. 4 illustrates a block diagram of one embodiment of a
`capacitance sensor including a relaxation oscillator and digi
`tal counter.
`
`Computing devices, such as notebook computers, personal
`data assistants (PDAs), and mobile handsets, have user inter
`face devices, Which are also knoWn as human interface device
`(HID). One such user interface device is a keyboard. Key
`boards include a set of input keys for the computing device.
`The input keys may be standard typeWriter keys, such as the
`alphabetic letters and numbers. The input keys may also
`include several specialiZed keys, such as Enter, Control, Alt,
`Delete, Escape, Cursor keys, and the like.
`FIG. 1A illustrates a resistance matrix of a conventional
`keyboard. Conventional keyboard 100 includes a keyboard
`architecture using a resistance matrix. The resistance matrix
`includes multiple roWs Q(O-X2) 101(0)-101(2), and multiple
`columns (YO-Y2) 102(0)-102(2). All the roWs 101(0)-101(2)
`are each connected to a pull-up resistor (e. g., 103(0)-103(2)),
`and all the columns 102(0)-102(2) are each connected to a
`pull-doWn transistor (e.g., 104(0)-104(2)), such as an
`N-Channel MOSFET (N MOS). Above the resistance matrix
`there are multiple buttons 105(0)-105(8) (e.g., keyboard
`keys). Upon pressing a button, the corresponding roW and
`column (X, Y) Will be shorted together. For example, the roW
`X Will read “0,” otherwise the roW X is “1.”
`One example of the resistance matrix for a PC is a PS/2
`keyboard. The PS/2 keyboard typically has betWeen 101 and
`104 keys that are uniquely positioned in a resistance scan
`matrix. The scan matrix consists of M roWs and N columns,
`all of Which are electrically isolated from each other. On
`average, the number of roWs (M) is no greater than 8, and the
`number of columns (N) is no greater than 20. Each key sits
`over tWo isolated contacts of its corresponding roW and col
`umn in the scan matrix. When a keyboard key 108 is pressed,
`the tWo contacts 106 and 107 are shorted together, and the roW
`and column of the keyboard key 108 are electrically con
`nected, as illustrated in FIG. 1B.
`The PS/2 keyboard may include an embedded controller
`that performs a variety of tasks, all of Which help to cut doWn
`on the overall system overhead. The PS/2 controller may
`monitor the keys and report to the main computer Whenever a
`keyboard key is pressed or released. FIG. 1C illustrates scan
`results for no keyboard keys pressed on a conventional resis
`tance scan matrix. The controller Writes a scanpattern 109 out
`to the column lines consisting of all ls and one 0 Which is
`shifted through each column. In FIG. 1C no keyboard keys are
`pressed, resulting in all is in the scan results 110 being read at
`the roW lines. FIG. 1D illustrates scan results for a keyboard
`key 111 pressed on a conventional resistance scan matrix. The
`controller Writes a scan pattern 112 out to the column lines
`consisting of all ls and one 0 Which is shifted through each
`column. The scan results 113 are then read at the roW lines. If
`a 0 is propagated to a roW line, then the key 111 at the
`intersection of that column and roW has been pressed.
`The conventional resistance scan matrix designs described
`have large pin counts because every roW and every column is
`connected to a pin. The pin count for these conventional
`resistance matrix keyboards is the sum of the number of roWs
`and the number of columns. For example, the PC keyboard
`needs at least 21 pins to build a resistance scan matrix. Having
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`
`US 8,059,015 B2
`
`3
`FIG. 5A illustrates a top-side vieW of one embodiment of a
`sensor array having a plurality of sensor elements for detect
`ing a presence of a conductive object on the sensor array of a
`touch-sensor pad.
`FIG. 5B illustrates a top-side vieW of one embodiment of a
`sensor array having a plurality of sensor elements for detect
`ing a presence of a conductive object on the sensor array of a
`touch-sensor slider.
`FIG. 5C illustrates a top-side vieW of one embodiment of a
`tWo-layer touch-sensor pad.
`FIG. 5D illustrates a side vieW of one embodiment of the
`tWo-layer touch-sensor pad of FIG. 5C.
`FIG. 6A illustrates one embodiment of a single sensor
`element of a sensing device that has three keyboard keys
`assigned to pre-de?ned areas of the sensing device.
`FIG. 6B illustrates one embodiment of a processing device
`coupled to a sensing device that has a capacitance sensor
`matrix and multiple keyboard keys assigned to pre-de?ned
`areas of the sensing device.
`FIG. 6C illustrates one embodiment of a processing device
`coupled to a sensing device that has a capacitance sensor
`matrix and keyboard keys A-Z assigned to pre-de?ned areas
`of the sensing device.
`FIG. 6D illustrates one embodiment of a handheld device
`having a keyboard.
`FIG. 7 illustrates a ?owchart of one embodiment of a
`method for detecting a position of a pressed key on a sensing
`device.
`FIG. 8 illustrates a table of one exemplary embodiment of
`output positions of multiple keyboard keys.
`
`DETAILED DESCRIPTION
`
`Described herein is an apparatus and method for selecting
`a keyboard key based on a position of a presence of a con
`ductive object on a sensing device and a pre-de?ned area of
`the keyboard key. The folloWing description sets forth numer
`ous speci?c details such as examples of speci?c systems,
`components, methods, and so forth, in order to provide a good
`understanding of several embodiments of the present inven
`tion. It Will be apparent to one skilled in the art, hoWever, that
`at least some embodiments of the present invention may be
`practiced Without these speci?c details. In other instances,
`Well-knoWn components or methods are not described in
`detail or are presented in simple block diagram format in
`order to avoid unnecessarily obscuring the present invention.
`Thus, the speci?c details set forth are merely exemplary.
`Particular implementations may vary from these exemplary
`details and still be contemplated to be Within the spirit and
`scope of the present invention.
`Embodiments described herein use a capacitance sensor
`matrix in a keyboard architecture to loWer a pin count
`betWeen a sensing device, Which includes the capacitance
`sensor matrix, and a processing device. This keyboard archi
`tecture may be implemented in a smaller area on a device,
`than the conventional architectures, such as the conventional
`scan matrix described above.
`As described in more detail beloW, the sensing device has a
`capacitance sensor matrix, Which includes multiple sensor
`elements that are con?gured in roWs and columns. The key
`board keys of a keyboard can be assigned a pre-determined
`area on the sensor matrix. The sensor matrix is used to detect
`a presence of a conductive object, such as a ?nger or a stylus.
`Each keyboard key, being assigned a different pre-determined
`area on the sensor matrix, Will provide a different capacitance
`variation from the sensor matrix to the processing device, as
`the conductive object is detected. The capacitance variation
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`can be measured on the multiple capacitance sensing pins that
`are used to couple the sensing device to the processing device.
`The capacitance variation measured on the capacitance sens
`ing pins can be used by the processing device to determine the
`x- and y-coordinate (e.g., X/Y location) of the detected pres
`ence of the conductive object on the sensing device. For
`example, 48 buttons are assigned into different pre-deter
`mined areas of a sensor matrix, having tWo roWs and tWo
`columns, as illustrated in FIG. 6B beloW. The tWo roWs and
`tWo columns are coupled to the processing device using four
`capacitance sensing pins. The capacitance variation mea
`sured on the four pins can be used to determine the position of
`the conductive object.
`As described in more detail beloW multiple keyboard keys
`can be assigned to pre-determined areas on a single sensor
`element. The capacitance variation measured on the capaci
`tance sensing pins can be used to distinguish Which keyboard
`key has been pressed. For example, a ?rst keyboard key,
`keyboard key A, is assigned between 1 and 3 in the x-direc
`tion, and betWeen 5 and 7 in the y-direction (e.g., {l<X<3 &
`5<Y<7}). A second keyboard key, keyboard key B, is
`assigned betWeen 5 and 7 in the x-direction andbetWeen 5 and
`7 in the y-direction (e.g., {5<X<7 & 5<Y<7}). If the A or B
`keyboard key has been pressed, the X/Y location should be
`Within the areas of A or B, respectively.
`Using the capacitance sensor matrix, the measurements on
`the capacitance sensor matrix (e. g., capacitance variation)
`may include additional information than just “connect” or
`“disconnect,” instead of only including “connect” or “discon
`nect” information in a conventional resistance matrix. The
`additional information is the location of the detected conduc
`tive object. The pressed key is outputted after comparing the
`located X/Y position of the conductive object and the pre
`de?ned areas of the capacitance sensor matrix.
`By assigning the different keys into different areas of the
`matrix and using the capacitance sensor matrix, the keyboard
`keys can be assigned to smaller areas than keys of a resistance
`matrix. This alloWs a keyboard (e.g., full personal computer
`(PC) keyboard, having 101 keys or more) to be implemented
`in smaller areas than the conventional keyboards that use
`resistance matrices. For example, a full keyboard having 101
`keyboard keys, for example, can be implemented on a mobile
`handset. Instead of sacri?cing real estate on a touch-screen
`display to implement the keyboard functions, the full key
`board can be mounted on the mobile handset as an additional
`user input device. This alloWs no sacri?ce to the real estate of
`the touch-screen display, and avoids increased costs of pro
`viding the additional keyboard functionality to the device that
`operates the touch-screen display.
`By decreasing the pin count of the keyboard, using the
`capacitance sensor matrix, the costs to manufacture the
`device also decrease. For example, the die cost is less than a
`device that requires more pins to implement the same number
`of keyboard keys. Similarly, by decreasing the pin count of
`the keyboard, the processing device may be used to further
`support other devices, such as additional user input devices
`(e.g., mouse, touch-sensor pad, touch-sensor sliders, touch
`sensor buttons, touch-screen displays, and the like).
`For example, in a PC interface, the keyboard and cursor
`positioning device (e.g., mouse or touch-sensor pad) are the
`most commonly used user input devices. Because the con
`ventional solution for keyboards require at least 21 general
`purpose input-output (GPIO) pins, and the cursor positioning
`requires about 12 GPIO pins, companies design tWo separate
`integrated circuits to control both user input devices (e.g., one
`higher pin count chip for the keyboard, and one loWer pin
`count chip for the cursor positioning device. HoWever, using
`
`

`
`US 8,059,015 B2
`
`5
`the capacitance sensor matrix described herein, a keyboard
`and a cursor positioning device may be controlled or sup
`ported by a single chip (e.g., processing device) because the
`pin count for the keyboard has been reduced using the capaci
`tance sensor matrix and capacitance sensing pins. Having a
`single chip reduces mask and die costs for the design.
`FIG. 2 illustrates a block diagram of one embodiment of an
`electronic system having a processing device for detecting a
`presence of a conductive object. Electronic system 200
`includes processing device 210, touch-sensor pad 220, touch
`sensor slider 230, touch-sensor buttons 240, host processor
`250, embedded controller 260, and non-capacitance sensor
`elements 270. The processing device 210 may include analog
`and/or digital general purpose input/output (“GPIO”) ports
`207. GPIO ports 207 may be programmable. GPIO ports 207
`may be coupled to a Programmable Interconnect and Logic
`(“PIL”), Which acts as an interconnect betWeen GPIO ports
`207 and a digital block array of the processing device 210 (not
`illustrated). The digital block array may be con?gured to
`implement a variety of digital logic circuits (e.g., DAC, digi
`tal ?lters, digital control systems, etc.) using, in one embodi
`ment, con?gurable user modules (“UMs”). The digital block
`array may be coupled to a system bus. Processing device 210
`may also include memory, such as random access memory
`(RAM) 205 and program ?ash 204. RAM 205 may be static
`RAM (SRAM), and program ?ash 204 may be a non-volatile
`storage, Which may be used to store ?rmWare (e.g., control
`algorithms executable by processing core 202 to implement
`operations described herein). Processing device 210 may also
`include a memory controller unit (MCU) 203 coupled to
`memory and the processing core 202.
`The processing device 210 may also include an analog
`block array (not illustrated). The analog block array is also
`coupled to the system bus. Analog block array also may be
`con?gured to implement a variety of analog circuits (e.g.,
`ADC, analog ?lters, etc.) using, in one embodiment, con?g
`urable UMs. The analog block array may also be coupled to
`the GPIO 207.
`As illustrated, capacitance sensor 201 may be integrated