(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2012/0188201 A1
`Binstead
`(43) Pub. Date:
`Jul. 26, 2012
`
`US 20120188201A1
`
`(54) TOUCH SENSOR
`
`(30)
`
`Foreign Application Priority Data
`
`(76) Inventor:
`
`Ronald Peter Binstead’
`Nottingham (GB)
`
`(21) Appl. No.:
`
`13/388,742
`
`(22) PCT Filed:
`
`Aug‘ 6’ 2010
`
`(86) PCT No.:
`
`PCT/GB2010/ 001489
`
`§ 371 (c)(1),
`(2), (4) Date:
`
`Apr. 11, 2012
`
`Aug. 6, 2009 (GB) ................................. .. 0913734.0
`Publication Classi?cation
`
`(51) Int. Cl.
`(2006-01)
`G06F 3/045
`(2006.01)
`G06F 3/041
`(52) US. Cl. ....................................... .. 345/174; 345/173
`(57)
`ABSTRACT
`
`A touch sensor for sensing user input comprising one or more
`elements. At least a portion of one or more if the elements is
`con?gured to be desensitized, in order to determine the loca
`tion of one or more user inputs.
`
`5'
`
`106
`
`108
`
`‘M112
`
`12345579/102
`
`111
`
`I - - ,XH
`I
`I
`Multiplexed 64 position keypad/ touchscreen with
`16 inputs showing the position of two fingers
`F0 and F1
`
`TPK 2016
`Wintek v. TPK Touch Solutions
`IPR2013-00568
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 1 0f 23
`
`US 2012/0188201 A1
`
`Figure 1a
`
`Figure 1b
`
`L~/
`$—{~:::::: g’iDé
`
`SEIIIII?II
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`J 104
`
`ttjTITs%LEA//1OZ
`
`X
`
`108
`
`112
`
`- - xk/
`Multiplexed 64 position Keypad/ touchscreen with
`16 inDuts showing the position of two fingers
`F0 and F1
`
`1 UH]!IIHHHIHllllllllllllllll
`
`32
`
`/
`
`154
`
`160
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 2 0f 23
`
`US 2012/0188201 A1
`
`Figure 2
`
`204
`
`208
`
`200
`
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`
`A
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`wilful 1mm!
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`HHH ll HHHH HHH ll HHH H HUI] H IIJJHH
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`W 202
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 3 0f 23
`
`US 2012/0188201 A1
`
`Figure 3
`
`304a
`
`Touch
`Sensors
`
`Broad
`Mask
`
`Masked
`561150
`
`Rest cted
`nsors
`
`
`
`a’ m @ mum; Bl P @ llllllll WW“ llllllll e WWW
`
`
`
`
`
`
`
`
`
`
`
`Effect of moving "windowed" mask up the sensor elements
`Blacked out parts of touch sensors represents the sensing
`
`T
`304
`
`T
`306
`
`T
`308
`
`302
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 4 0f 23
`
`US 2012/0188201 A1
`
`Flgure 4
`
`a)
`
`C)
`
`Unrestricted
`Sensors
`
`Narrow
`Mask
`
`Masked
`Sensors
`
`Restricted
`Sensors
`
`:1
`
`(
`
`time
`
`|:::]
`
`P
`
`Effect of moving Narrow mask up sensing elements.
`
`d) llllllllmii?iiiiiiiii
`
`T
`402
`
`T
`404
`
`T
`406
`
`T
`408
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 5 0f 23
`
`US 2012/0188201 A1
`
`Figure 5
`
`time *’
`
`1) Normal linear sequence scan using a broad mask
`
`502
`
`2)
`
`Mask gets progressively bigger I
`a m-FH
`
`3) Mask moves down the screen in big steps but stays the same size
`
`K HA5}
`
`4) Mask swaps around the screen and gets progressively smaller
`
`Various methods of masking by successive approximation.
`:1 indicates position of touch to be detected.
`Blacked out areas indicate the touch inhibiting mask.
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 6 0f 23
`
`US 2012/0188201 A1
`
`Figure 6
`
`602
`
`/
`
`612
`
`600
`
`/
`
`31
`
`?
`edge shielding bezel
`x4
`5
`x6
`x7 /x8
`‘1 7 j ‘w 71 1 1/1
`
`X2
`
`213
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`—— é ——
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`u
`edge shielding bezel
`
`/
`
`Front view of screen, showinq eiqht horizontal
`driven elenents(y), and eight vertical sensing
`elements“)
`Seven of the drive elements are shown connected to
`ground while the eighth is connected to the Active
`Backplane.
`
`F0 to F9 show ten hypothetical simultaneous touch
`finger positions‘
`
`Touch sensitive areas shown by
`
`—
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 7 0f 23
`
`US 2012/0188201 A1
`
`620
`
`622
`
`/ /
`618
`\ adhesive H Ié_—
`insulator\$
`
`c
`
`d
`
`?
`
`Figure 7
`
`612
`
`Shielding Id’,
`bezel
`Y9
`
`610
`
`Y7
`Uv/
`
`c<<d
`
`F2 / 602
`
`/624
`
`'
`
`F5
`
`04
`
`Uv /
`
`x4 sensing
`element
`
`Y1
`
`shielding
`bezel
`
`/
`
`_/606
`
`Connect ion to
`electronic.
`circuit .
`
`608
`
`l
`1:
`Section e-b view from Fig 3. showing eight driven
`horizontal elements (31)‘ and one vertical sensing
`element (34),
`
`Seven of the drive elements are shown connected to
`ground while the eighth is Connected to the Active
`Backplane,
`Touch sensitive areas shown by
`
`Figure 8
`
`Relationship between x touch sensing element, v
`element mask and finger.
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 8 0f 23
`
`US 2012/0188201 A1
`
`Figure 9
`
`910
`
`900
`
`HOMWU
`
`908
`
`Data;
`
`8 mask
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 9 0f 23
`
`US 2012/0188201 A1
`
`Flgure 10
`
`1006
`
`1002
`
`1000
`
`8
`
`1004
`
`Front view of screen showing eight horizontal plate
`type driven elements, eight horizontal wire sensing
`elements, '1‘ and eight vertical wire sensing
`elements, 1-:
`In mask mode. seven of the horizontal plate elements
`are Connected to ground, while the eighth is
`connected to the Active Backplane, ABP 4
`In x/y multiplexed mode‘ all eight horizontal plate
`elements are connected to the Active Hackplane‘
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 10 0f 23
`
`US 2012/0188201 A1
`
`Figure 11
`
`Reer
`swltch
`elements
`
`Touch
`sensing
`element
`
`1108
`
`1106
`
`1104
`
`1102
`
`Glass, or clear
`plastic front panel
`
`1110
`
`1 of B
`HUX
`
`1112
`ABP /
`£4: Du / 1 1
`
`Simple
`touch
`sensor
`circuit
`
`RC Oscillator
`
`s
`
`TL
`
`_
`it
`anverter
`
`Single capacitance touch eensitive element in front of
`an eight element electronically switchable mask.
`
`Seven 0! the driye elements are shown connected I to
`ground ( nu ), vhllc one 15 connected to the Actlve
`Backplane.
`/
`Touch sensitive areas shown by
`— ///
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 11 0f 23
`
`US 2012/0188201 A1
`
`Figure 12
`
`1202
`
`One of
`eight
`rear
`switch
`elements
`
`Single
`Touch
`sensing
`element
`
`1204
`
`Glass, or clear
`plastic tron! panel
`
`1214
`
`1210
`
`1212
`
`ABP/
`
`RC Oscillator
`
`s
`
`TL
`
`inverter
`
`Single capacitance touch sensitive element in front of
`an eight element electronically switchable mask.
`
`All of the switch elements are shown connected to ground (0") ,
`through res1stors.while one at a time is connected to the Active
`Backplane (ABP).
`Touch sensitive areas shown by
`
`I
`— ///
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 12 0f 23
`
`US 2012/0188201 A1
`
`Figure 13
`
`Continuous rear
`a
`ground pl he
`
`Normally
`“floating”
`switch
`elements
`
`Touch
`sensing
`element
`
`1304
`
`1302
`
`1318
`
`Glass. or clear
`plastic front panel
`
`1310
`
`1312
`ABP /
`
`RC Oscillator
`stor
`
`tt
`inverter
`
`Single capacitance touch sensitive element in front of
`an eight element electronically switchable mask
`Hi (.11 a grounded conductive plane at the
`rear.
`Seven of the switch elements are shown 'floating“
`while one is connected to the Active Backplanelhal?) .
`
`Touch sensitive areas shown by
`
`,
`
`_
`
`/
`
`- //I
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 13 0f 23
`
`US 2012/0188201 A1
`
`Figure 14a
`
`1402
`
`1410
`
`1404
`
`Non mnduct ive
`conductive
`front panel
`sensing element
`A ‘L
`
`Active Backplane
`ABP
`
`v
`
`No sensing
`in this zone
`
`(
`
`r
`
`/
`
`Rea; t.
`/' ‘Sign? Ive
`
`Lf'g
`H.
`
`1420
`
`Grounded wire “9
`
`switch set to ground
`
`Ground or 0v \
`1424
`1408
`
`RC Oscillator
`
`Simple
`toucl? \
`
`[Touch sensing turned OFF
`
`—l
`
`inverter
`
`Figure 14b
`
`conduct ive
`sensi ng element
`
`Non conductive
`front panel
`J
`I
`
`Sensing in
`th‘ is zone
`
`(I ll
`'
`
`//.
`L j
`/ if
`.Cl
`Rear 7 ”-
`conductive
`
`1: ate
`
`Active Baal-(plane
`A8?
`
`switch set to ABP
`
`L‘ Ground or 0v
`
`RC Oscillator
`
`1424
`
`4/
`
`l Simple
`touch
`
`sensing circuit
`
`?
`
`Eouch sensing turned 0}:
`
`_|
`
`inverter
`
`Touch sensing switch.
`Single capacitance touch sensitive element in front of
`a single mechanically or electronically Switchable mask element.
`
`Touch sensitive areas shown by
`
`- 7/,
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 14 0f 23
`
`US 2012/0188201 A1
`
`Figure 15a
`
`Finger- 4 9
`
`U 5 6
`
`1 7
`
`3 3
`
`2
`
`Y —‘ l
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`8
`
`Iypieal x and y_values generated bv _a screen as
`1n P19 3 4 used 111 standard x/y multlplexed mode,
`
`Figure 15b
`
`U1
`
`wlndowed y element
`
`measured 2: sensor value
`
`Typical 1-: values generated by a screen, as
`in Fig 3 . used in masked mode.
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 15 0f 23
`
`US 2012/0188201 A1
`
`Figure 16
`
`1600
`
`B—EIIIWIIIIITII
`
`1—EI:::::::1
`
`Ti‘r’r’r’r’r‘r
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`B
`
`1604
`
`1606
`
`/ / 1602
`
`F0
`
`F1 /
`
`1608\\\"\>
`v \ 7
`123456
`B
`Tvpigal sensor reading using standard x/y
`multlplexed keypad/touchscreen (Mode 2)
`
`1610
`
`F0
`
`F1 ‘/1612
`
`1-: values when 376 is grounded (Mode 3)
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 16 0f 23
`
`US 2012/0188201 A1
`
`Figure 17
`
`F161?
`
`1,
`\1,
`_______1_7_T
`
`/
`'
`
`1700
`
`3——E:::::(Fn)::(nf:]é—/
`2——E:::::::T::]
`
`A 1/
`
`1708
`
`lfIIIIIIII]
`
`1
`
`2
`
`3
`
`4 x 5
`
`B
`
`7
`
`8 K
`
`17a
`
`H
`
`- -
`
`L lo
`
`9
`7
`B
`5
`4
`3
`2
`1
`Typical sensor reading using standard x/y
`multiplexed keypad/touchscreen when two fingers
`are on the same 3! sensor/control elemew’
`
`Effect on 1-: Sensor values when v4 is grounded
`
`- -
`17bx
`" 1706
`Y‘ , h /
`1
`2
`3
`4
`S
`6
`7
`8
`Change in y sensor values as finger Fl moves
`up the screen toward 374
`
`A x
`
`B
`7
`6
`5
`4
`3
`2
`1
`Effect on 1-: sensor values when v4 is grounded
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 17 0f 23
`
`US 2012/0188201 A1
`
`Figure 18
`
`1800
`
`View of screen showing eight y driving/sensing
`wires and eight 1-: sensing/driving wires
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 18 0f 23
`
`US 2012/0188201 A1
`
`Figure 19
`
`1900
`
`M
`% +2 2
`
`8 7
`V. V.
`
`a: Q. .1 g 2. M,
`2*; Z i
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 19 0f 23
`
`US 2012/0188201 A1
`
`Figure 20
`
`2000
`
`/
`
`v2
`
`View of screen showing eight 51 driving/sensing
`wires and eight 1: sensing/driving wires, patterned
`to maximise the capacitance cross coupling between
`the x and y wires
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 20 of 23
`
`US 2012/0188201 A1
`
`Figure 21
`
`2100
`
`2012
`
`\5 x1
`
`x2
`
`x3
`
`ABP
`
`x4
`
`x5
`
`x6
`
`x7
`
`x8
`
`———u———_— VB
`_—m———-—
`
`
`
`
`
`
`
`
`
`
`-—-_---_
`--m--_-- 97
`__fl—____
`
`—_-—__— 316
`——-l—-_-
`--fl—--_ 3,5
`---——--
`--__---
`——l-————_ 5,4
`———————-
`_--l—---
`_-fl____ 3
`---_--— V
`-_—Il-—__—
`
`L I_—___—— Y2
`---l___—
`_4 I———__—-_ 1
`'_| -- .
`'\.
`-—- Y
`
`“nun—nn-‘n k 2104
`
`
`View of screen with eight vertical,x,driven elements
`and eight horizontal fine wire,y,sensing elements.
`Hatched area 33 is shown connected to the active
`backplane while all non hatched x elements are
`connected to ground (0v).
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 21 of 23
`
`US 2012/0188201 A1
`
`Figure 22
`
`edge shielding bezel
`
`
`
`Edgeshielding bezel
`
`Front viev of screen. showinq eiqht horizontal
`driven elements(y) , and eight vertical
`full width sensing elements(x).
`Seven of
`the drive elements are shown connected to
`ground while the eighth is connected to the Active
`Backplane.
`
`Touch sensnwe areas shown by
`
`/
`- 4'
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 22 of 23
`
`US 2012/0188201 A1
`
`Figure 23
`
`0v
`0v
`0v
`0v
`0v
`ABP
`0v
`
`Dv
`
`2300
`
`sensor input
`
`sensor plate
`
`Rear mask
`
`.
`Middle
`Touch sensitive
`plate
`
`Perforated
`Front mask
`
`
`lliiiiiii‘l‘ill
`null-lulnl
`annulus-nu
`Iflllllllfll
`null-Inga!
`:nnnunaan
`lflllllllfl
`ausgggggu
`IIIIIIIIIIIiIIII
`
`
`
`All three plates superimposed on each other
`
`
`
`
`
`2308
`
`K//
`
`h
`T
`gme
`mm
`
`Example of extreme masking
`
`

`

`Patent Application Publication
`
`Jul. 26, 2012 Sheet 23 of 23
`
`US 2012/0188201 A1
`
`Figure 24
`
`w /
`
`inductive sensing loDD ext“
`
`
`to
`Output
`Micro‘processor
`
`2412
`a) Circuit of a oseillator, connected to a long inductive sensing coil 11
`/
`2414
`I’m
`
`
`
`
`
`
`
`closed
`wire
`loop
`
`desensitized
`zone
`
`desensitized
`
`2420
`
`L1
`
`12L3
`14
`
`
`
`
`
`From micro—
`processor
`
`d) Diagram showing four inductive sensing loops crossed by five electronically
`elosable loops‘
`
`

`

`US 2012/0188201A1
`
`Jul. 26, 2012
`
`TOUCH SENSOR
`
`[0001] The present disclosure relates to the field of touch
`sensors, and particularly, although not exclusively, touch sen-
`sors that can distinguish between multiple simultaneous user
`inputs/touches.
`[0002] Touch sensors, which may also be referred to as
`touch screens, that use multiplexed arrays of horizontal and
`vertical sensor elements, are known as described in US. Pat.
`No. 6,137,427 (Binstead) for example. Such touch sensors
`work well with one finger operation, where one peak is iden-
`tified by elements in the horizontal direction (x) and one peak
`is identified in the vertical direction (y). In this example, the
`location ofthe touch can be unambiguously determined as an
`x/y finger co-ordinate by putting together the single peak in
`the horizontal direction and the single peak in the vertical
`direction.
`
`[0003] However, prior art multiplexed arrays have prob-
`lems with correctly detecting the location of two simulta-
`neous finger presses, as there will be two peaks in the hori-
`zontal (x) direction and two peaks in the vertical direction (y).
`The problem is how to identify which x peak is associated
`with which y peak, and is illustrated in FIG. 1a.
`[0004]
`FIG. 1a illustrates schematically a prior art multi-
`plexed 64 position touch sensor with sixteen sensing ele-
`ments/inputs. Eight sensing elements are provided along the
`horizontal (x) axis of the touch sensor, and are labelled with
`reference 102. Eight sensing elements are provided along
`vertical (y) axis of the touch sensor, and are labelled with
`reference 104. The eight horizontal sensing elements 102 and
`eight vertical sensing elements 104 provide 64 touch sensing
`cross-over points/intersections.
`[0005]
`Shown in FIG. 1a are two finger presses: finger F0
`108 at a location of intersect ion 5/3 of the x/y sensing ele-
`ments; and finger F1 106 at a location of intersect ion 7/6 of
`the x/y sensing elements. The information returned by the
`horizontal sensing elements 102 is shown graphically with
`reference 110 in FIG. 1a, and the information returned by the
`vertical sensing elements 104 is shown graphically with ref-
`erence 112. It canbe seen that the information 110 returned by
`the horizontal sensing elements 102 shows two “peaks” at
`horizontal locations 5 and 7, and the information 112 returned
`by the vertical sensing elements 104 shows two “peaks” at
`vertical locations 3 and 6.
`
`[0006] Using the information 110, 112 returned by the hori-
`zontal and vertical sensors 102, 104 results in an ambiguity as
`it cannot be determined if the fingers are at locations 5/3 and
`7/6 (which are the correct locations of the fingers) or at
`locations 5/6 and 7/3. Insufficient data is available, with a
`normal x/y multiplexed scan, to determine the correct finger
`positions.
`[0007] The problem of ambiguity gets worse with three or
`more fingers, or when several fingers are held still on a com-
`mon sensor element and one finger starts to move. Knowing
`which of the fingers is moving can be difficult to resolve.
`[0008] One known way around these problems is to use a
`non-multiplexed array of sensing elements, such as the one
`shown in FIG. 1b.
`
`[0009] The touch sensor 150 of FIG. 1b is made up of a
`number of discrete keys 152, each of which is sensitive to
`touch and has its own independent sensing input. Thirty two
`sensing inputs are shown with reference 154 in FIG. 1b and
`correspond to the thirty two keys 152 on the left-hand side of
`
`the touch sensor 150, and thirty two sensing inputs are shown
`with reference 156 in FIG. 1b and correspond to the thirty two
`keys 152 on the right-hand side of the touch sensor 150. The
`two fingers, F0 (160) and F1 (158), are uniquely identified as
`being at inputs 56 and 42 respectively. Therefore, the non-
`multiplexed array of FIG. 1b is capable of detecting the posi-
`tion of a number of fingers at the same time, without ambi-
`guity.
`[0010] A problem with the non-multiplexed approach of
`FIG. 1b is the large number of sensing elements required (one
`sensing element per key 152), and the complexity of connec-
`tions to these elements. The 8x8 multiplexed array of FIG. 111
`requires 16 sensing elements (eight in the x direction and
`eight in the y direction), whereas the non-multiplexed equiva-
`lent of FIG. 1b requires 64 sensing elements (one per key
`152). It will be appreciated that a 32x32 multiplexed array
`requires 64 inputs, whereas its non-multiplexed equivalent
`requires 1024 sensing elements, each of which require con-
`nection to an electronic controller.
`
`[0011] Another problem with 64 non-multiplexed separate
`sensing elements (FIG. 1b), is that each of the 64 elements
`require a conductive route back to the controller electronics,
`with the conductive route for most of the elements having to
`traverse the viewing/sensing area. Apart
`from visually
`obscuring the screen, these tracks have a small negative
`impact on detection accuracy.
`[0012] The listing or discussion of a prior-published docu-
`ment or any background in the specification should not nec-
`essarily be taken as an acknowledgement that the document
`or background is part of the state of the art or is common
`general knowledge.
`[0013]
`In the following description, the terms grounded,
`disable, and desensitize are examples ofwords that are used to
`describe a principle of desensitizing part of an element, and
`can include using a control element to desensitize part of a
`sensing element.
`[0014]
`“Grounding” may include, connecting to true
`ground, or earth potential, connecting to io another fixed
`potential, connecting to a fixed, but floating potential (for
`example when equipment is battery operated), connecting to
`an anti-active backplane signal or other interfering signal.
`[0015] The terms ungrounded, enable, and sensitize are
`examples of words that are used to describe a principle that
`includes sensitizing part of a sensing element,
`[0016]
`“Ungrounding” may include connecting to an active
`backplane signal or allowing an element to float, i.e., not be
`resistively connected to anything.
`[0017] According to a first aspect of the invention, there is
`provided a touch sensor comprising:
`[0018]
`one or more elements;
`[0019] wherein at least a portion of the one or more
`elements is configured to be desensitized in order to
`determine the location of one or more user inputs.
`[0020] Desensitizing at least a portion of one or more ofthe
`elements can be considered as providing a mask to the touch
`sensor such that the location of one or more user inputs can be
`determined. Desensitizing at least a portion of one or more of
`the elements can enable fewer sensing inputs to be required in
`order to unambiguously determine the locations of one or
`more user inputs.
`[0021] At least a portion of the one or more elements may
`be configured to be desensitized in order to distinguish
`between multiple user inputs. The elements may be linear or
`non-linear.
`
`

`

`US 2012/0188201A1
`
`Jul. 26, 2012
`
`[0022] The touch sensor may be one or more of a capacitive
`touch sensor, or an inductive sensor, a resistive sensor, or any
`other type of sensor. In some examples, the touch sensor may
`use a combination of different sensor technologies.
`[0023] The one or more elements may comprise one or
`more sensing elements.At least a portion ofone or more ofthe
`sensing elements may be configured to be capacitively
`coupled to ground to be desensitized. At least a portion of one
`or more of the sensing elements may be configured to be
`capacitively, inductively or resistively coupled to ground to
`be disabled. The sensing element may be coupled to ground in
`the same way that the sensor senses touch; for example, a
`capacitive touch sensor may have sensing elements that are
`capacitively coupled to ground to be desensitized. In other
`embodiments, the portion(s) of the one or more sensing ele-
`ments may be configured to be coupled to a fixed voltage, an
`anti-backplane signal, or any other signal that is not an active
`backplane signal, in order to be desensitized. At least a por-
`tion ofone or more ofthe sensing elements may be configured
`to be coupled to an active backplane signal to be sensitized.
`The touch sensor may comprise a switch configured to couple
`the sensing element to either ground or the active backplane.
`[0024] At least a portion of one or more of the sensing
`elements may be configured to be coupled to an element that
`is electrically floating to be sensitized. “Electrically floating”
`may be considered as not being connected to ground, or an
`active backplane signal, or any other terminal. The touch
`sensor may comprise a switch configured to couple the sens-
`ing element to ground or to an element that is electrically
`floating.
`[0025] The touch sensor may comprise one or more con-
`trollable elements. A region of a controllable element may be
`proximal to a region of a sensing element in order to provide
`a sensing region of the sensing element.
`[0026] The one or more sensing elements may be aligned in
`a different direction to the one or more controllable elements
`
`such that the sensing elements and controllable elements
`intersect in order to provide the sensing region.
`[0027] At least part of the one or more sensing elements
`may be aligned in substantially the same direction as, and
`proximal to, at least part of one or more of the controllable
`elements in order to provide the sensing region.
`[0028] Use of controllable elements and sensing elements
`can enable fewer sensing inputs to be required than is neces-
`sary for the prior art. The touch sensor may comprise x sens-
`ing inputs, where x equals the number of sensing elements,
`which may be the number of columns or the number of rows
`of the touch sensor, for example.
`[0029] Embodiments of the invention can enable sensing
`elements to only be required for one dimension of a two-
`dimensional touch sensor. User input along the first dimen-
`sion can be distinguished by the sensing elements; and user
`input along the second dimension can be distinguished by
`sensitizing or desensitizing parts of these sensing elements,
`which may be performed sequentially. Sensitizing or desen-
`sitizing parts of the sensing elements can be performed by
`enabling or disabling one or more of the controllable ele-
`ments
`
`[0030] The direction of the sensing elements may be sub-
`stantially perpendicular to the direction of the controllable
`elements,
`for keypad or
`touchscreen applications
`for
`example. For other applications, the arrangement may be
`more complex or customised.
`
`[0031] The controllable elements may be configured to be
`disabled/grounded such that the sensing regions are either
`sensitized or desensitized.
`
`[0032] The touch sensor may be configured to couple a
`controllable element to ground in order to desensitize the
`corresponding sensing regions. The corresponding sensing
`regions of the one or more sensing elements can be desensi-
`tized as they are capacitively coupled to the controllable
`element that is coupled to ground.
`[0033] The touch sensor may be configured to leave a con-
`trollable element electrically floating in order to enable the
`full sensitivity of the corresponding sensing regions.
`[0034] The touch sensor may comprise a switch configured
`to couple a controllable element to ground in order to disable
`the corresponding sensing regions; or leave the controllable
`element electrically floating to enable the controllable ele-
`ment,
`thereby providing full sensitivity of the sensing
`regions.
`[0035] The touch sensor may be configured to couple a
`controllable element to an active backplane signal in order to
`enable full sensitivity of the corresponding sensing regions.
`[0036] The touch sensor may comprise a switch configured
`to couple a controllable element to ground in order to desen-
`sitize the corresponding sensing regions, or couple the con-
`trollable element to the active backplane signal to sensitize
`the corresponding sensing regions.
`[0037] There may be a switch for each controllable ele-
`ment.
`
`[0038] The switch, or switches, may be electronic switches.
`In this way, operation ofthe touch sensor can be automatically
`operated and can provide a responsive touch sensor.
`[0039] The touch sensor may comprise a controller. The
`controller may be configured to operate the switch, or
`switches, in accordance with information received from one
`or more of the sensing elements.
`[0040] The controller may be configured to operate these
`switches in order to periodically disable/ground one or more
`of the controllable elements or otherwise control the control-
`
`lable elements. Ifone, or only a few, controllable elements are
`disabled/grounded at the same time, then this can be consid-
`ered as providing a narrow mask. The controller may be
`configured to operate the switches, or otherwise control the
`controllable elements, in order to periodically disable/ground
`all except one of the controllable elements. The controller
`may be configured to enable a single controllable element in
`turn. This can be considered as providing a broad mask.
`[0041] The controller may be configured to determine
`which of the controllable elements should be disabled/
`
`grounded in order to distinguish between multiple user inputs
`represented by the signals returned from one or more of the
`sensing elements.
`[0042] The controller may be configured to disable/ground
`a previously enabled controllable element that intersects with
`a sensing element at a location that corresponds to a location
`of one of the multiple user inputs. The controller may be
`configured to control a controllable element in order to desen-
`sitize a previously sensitized corresponding sensing region
`that corresponds to a location of one of multiple user inputs.
`For example, ifuser input is received at locations correspond-
`ing to two different enabled controllable elements, then the
`controller can ground/disable one of the previously enabled
`controllable elements such that the two user inputs can be
`distinguished.
`
`

`

`US 2012/0188201A1
`
`Jul. 26, 2012
`
`[0043] The controller may be configured to operate all ele-
`ments as sensing elements until multiple user inputs are
`received, or until multiple user inputs are not distinguishable
`from each other. The controller may then operate one or more
`of the elements as controllable elements in order to distin-
`
`guish between multiple user inputs.
`[0044] The controller may be configured to control the
`controllable elements in order to sensitize all of the sensing
`elements, and the controller may be configured to repeatedly:
`[0045]
`receive information from the sensing elements;
`and
`
`in response to the information received from the
`[0046]
`sensing elements, control the controllable elements in
`order to desensitize corresponding sensing regions;
`until multiple user input is distinguishable.
`[0047] The controller may be configured to ground a
`former/previously sensing element at a location that corre-
`sponds to one of multiple user inputs. The controller may be
`configured to change the operation of an element from a
`sensing element to a controllable element in order to distin-
`guish between multiple user inputs. For example, if io user
`input is received at locations corresponding to two different
`sensing x inputs, or two different sensing y inputs, then the
`controller can use/operate one of these sensing elements as a
`controllable element and ground/disable it, so that the two
`user inputs can be distinguished.
`[0048] All of the sensing elements may also be configured
`as controllable elements, and the controller may be config-
`ured to control the controllable elements such that a single
`sensing region between two controllable elements is config-
`ured to be touch sensitive.
`
`[0049] The signals returned from one or more of the sens-
`ing elements may be received when none of the controllable
`elements are disabled/grounded. A scan when none of the
`controllable elements are disabled/grounded may be referred
`to as an x/y scan, and may involve all of the elements being
`used as sensing elements. Such an example can provide for
`fast operation to detect when a finger touches the screen. A
`disambiguating scan may only be performed (only consid-
`ered necessary) when two or more fingers touch the screen.
`[0050] The controller may be configured to enable all ofthe
`controllable elements and the controller is then configured to
`repeatedly:
`[0051]
`and
`
`receive information from the sensing elements;
`
`in response to the information received from the
`[0052]
`sensing inputs, ground various combinations of these
`elements and/or increase or decrease the number of dis-
`
`abled controllable elements until multiple user input is
`distinguishable.
`[0053] This an example of how a mask can be gradually
`increased in size until multiple user input is distinguishable,
`and may enable successive approximation and binary chop-
`ping to be performed.
`[0054]
`In some embodiments, one or more of the elements
`may never be used to sense touch, but are permanently con-
`figured as controllable (masking) elements. The controllable
`elements may be connected either to ground or to the active
`backplane, and this can enable multiple user inputs to be
`efficiently distinguished with less sensor elements.
`[0055]
`In other embodiments, one or more of the sensing
`elements can be configured to be both sensing elements and
`controlling elements, and, at different times, will be either
`one or the other.
`
`In some embodiments, all of the elements may be
`[0056]
`controller elements, with a single, universal sensor element.
`The controller may be configured to periodically disable/
`ground all except two ofthe controllable elements such that a
`single intersection between the two enabled/ungrounded con-
`trollable elements is configured to be touch sensitive. The two
`controllable elements that are not disabled may extend in
`different directions, for example they may be orthogonal to
`each other.
`
`In an example where both row elements and column
`[0057]
`elements can be, alternately, both control and sensing ele-
`ments, and either the row elements are sensing elements
`while the column elements are control elements, or the col-
`umn elements are sensing elements while the row elements
`are control elements, then one sensing element; and one con-
`trol element can be selected, sequentially, one after another,
`so that it is possible to unambiguously sense each intersection
`between a row and column element. Thus, for an 8x8 sensor
`pad, each ofthe 64 intersections can be sensed separately. All
`of the sensing inputs can be routed to a single sensing input
`circuit, as only one of the sensing elements will be enabled at
`a time.
`
`[0058] As both the sensing methods described above (that
`is, a row sensing with column controlling method/scan, and a
`column sensing with row controlling method/scan) measure
`the same thing, but in two different ways, then the two sensing
`methods can be used to improve the accuracy ofthe detection.
`The results ofone scan can be compared with the results ofthe
`other scan to determine whether or not they represent the
`same user inputs, thereby increasing confidence in the results.
`Alternatively, both results can be combined together to pro-
`duce a composite result, with greater accuracy. This can be
`considered, in effect, as similar to “double-entry” bookkeep-
`ing.
`[0059] Alternatively, if a whole row, or column of elements
`is to be sensed at exactly the same time, then one sensing input
`circuit will be required for each of the rows or columns. This
`will require the number of inputs to equal to the number of
`rows plus the number of columns. This would be 16 for an
`example 8x8 sensor pad. In the example described in this
`paragraph, however, rows and columns are never both used as
`sensors at the same time, so, this number can be decreased by
`routing row and column inputs to a common bank of inputs
`circuits. This would require the number of inputs to be equal
`to the greater ofthe row or column numbers, which is 8 for an
`8x8 sensor pad. In these examples, all of the sensing inputs
`can be routed to a single sensing input circuit, as only one of
`the sensing elements can be enabled at a time.
`[0060] A compromise between the two extremes of having
`a separate input circuit for each input, and one input circuit to
`serve all ofthe inputs, is to have a small bank of input circuits
`that can be sensed at the exact same time, such as four, for
`example. Row or a column inputs can be routed to this com-
`mon bank of four input sensors circuits.
`[0061] The se