Part 1: Fundamentals of
`
`Projected-Capacitive
`Touch Technology
`
`Geoff Walker
`
`1
`
`Senior Touch Technologist
`Intel Corporation
`
`June 1, 2014
`
`File Download: www.wa|kermobiIe.comI'l'ouch_Technologies_TutoriaI_Latest_Version.pdf
`
`SID DISPLAY WEEK‘14 V12
`
`
`
`Projected-Capacitive
`Touch Technology
`
`Geoff Walker
`
`1
`
`Senior Touch Technologist
`Intel Corporation
`
`June 1, 2014
`
`File Download: www.wa|kermobiIe.comI'l'ouch_Technologies_TutoriaI_Latest_Version.pdf
`
`SID DISPLAY WEEK‘14 V12
`
`
`
`Agenda
`
`°:~ Introduction
`
`oto Basic Principles
`
`oz» Controllers
`
`«:o Sensors
`
`«:0 ITO-Replacement Materials
`
`«:0 Modules
`
`«:0 Embedded
`
`«to Large-Forrnat
`
`«:0 Stylus
`
`«to Software
`
`«:~ Conclusions
`
`v:~ Appendix A: Historical Embedded Touch
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Introduction
`
`°:~ P—Cap History
`
`0.0 P—Cap Penetration
`
`02° P—Cap by Application
`
`°t° Touch User-Experience
`
`File Download: www.walkermobile.comI'|'ouch_Technologies_TutoriaI_Latest_Version.pdf
`
`SID DISPLAY WEEK ‘l4
`
`3
`
`inte|'
`
`Must use exact
`
`capitalization!
`
`
`
`P-Cap History
`
`K Roya Radar
`Establishment
`
`E.A. Johnson
`
`CERN (Bent Stumpe)
`
`Dynapro Thin Films
`(acquired by 3M Touch
`S stems in 2000
`
`Zytronic (first license from
`Ronald Binstead, an
`inventor in the UK)
`
`Visual Planet (second
`license from Ronald
`
`Binstead
`
`Apple
`
`First published application of transparent
`touchscreen (mutual-capacitance p-cap on
`CRT air-traffic control tenninals
`
`Second published application of mutual-
`capacitance p-cap (in the control room of
`the CERN proton synchrotron)
`First commercialization of mutual-
`
`self-capacitive p-cap;
`first commercialization of large-format
`mutual—capacitive p-cap
`Second commercialization of large-format
`self-capacitive p-cap
`
`First use of mutual-capacitive p-cap in a
`consumer electronics roduct the iPhone
`
`‘65
`
`1977
`
`1995
`
`1998
`
`2012
`
`2003
`
`2007
`
`SID DISPLAY WEEK ‘l4
`
`
`
`P-Cap Penetration
`
`% of Units Shipped
`looy
`2.8% 2.4% 1.3%
`0
`
`2.5% 1.2% 0.6% 0.3% 0.3% 0.3% 0.2% 0.2% 0-2%
`
`90% .
`
`80%
`
`70%
`
`60%
`
`50% .
`
`T
`
`T
`
`T
`
`40%
`
`30%
`
`20%
`
`10%
`
`0%
`
`Embedded
`= P-Cap
`
`I Other Technologies
`
`I In-Cell (P-Cap)
`
`T
`
`T
`
`T
`
`IOn-Ce|l(P-Cap)
`
`I Resistive
`
`I P-Cap
`
`T
`
`T
`
`2007A 2008A 2009A 2010A 2011A 2012A 2013A 2014F 2015F 2016F 2017F 2018F
`
`Source: DisplaySearch Touch-Panel Market Analysis Reports 2008-2014
`
`SID DISPLAY WEEK ‘l4
`
`
`
`P-Cap Forecast by Application...1
`(Consumer)
`
`Million Units
`120
`
`I PDA
`
`I Desktop Monitor
`
`I Video Camera
`
`I All-in-one PC
`
`I Portable Game
`
`I Still Camera
`
`I EPD eReader
`
`I Media Player
`
`I Smart Watch
`
`I Navigation Device
`
`I Notebook PC
`
`2012
`
`2013
`
`2014
`
`2015
`
`2016
`
`2017
`
`2018
`
`#2013: Phones = 1.8 Billion Units; Tablets = 447 Million Units
`
`Source: Dispiaysearch Touch—Pane| Market Analysis Report 1Q—2014
`
`SID DISPLAY WEEK ‘14
`
`5
`
`ifieb
`
`
`
`P-Cap Forecast by Application...2
`(Commercial)
`
`Million Units
`8.0
`
`7.0
`
`6.0
`
`5.0
`
`4.0
`
`3.0
`
`2.0
`
`1.0
`
`0.0
`
`2012
`
`2013
`
`2014
`
`2015
`
`2016
`
`2017
`
`2018
`
`#2018: Automobile Monitor = 42 Million Units
`
`Source: Displaysearch Touch—Pane| Market Analysis Report 1Q—2014
`
`SID DISPLAY WEEK ‘14
`
`7
`
`I Education/Training
`
`I Point of Interest
`
`I Ticketing/Check-in
`
`I Casino Game
`
`I Medical Equipment
`
`I ATM Machine
`
`I Office Equipment
`
`I Retail and POS/ECR
`
`I Factory Equipment
`
`
`
`P-Cap Defines the Standard
`for Touch User-Experience
`
`«to Smartphones and tablets have set the standard
`for touch in SEVERAL BILLION consumers’ m
`
`+ Multiple simultaneous touches
`(robust multi-touch)
`+ Extremely light touch (zero force)
`+ Flush surface (“zero-bezel”
`
`’
`
`or “edge-to-edge”)
`
`+ Excellent optical performance
`
`+ Very smooth & fast scrolling
`
`+ Reliable and durable
`
`+ An integral part of the
`device user experience
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Basic Principles
`
`02* Self Capacitive
`
`'3 Mutual Capacitive
`
`~20 Mutual Capacitive Electrode Patterns
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Self-Capacitance
`
`03° Capacitance of a single electrode to ground
`
`+ Human body capacitance increases the capacitance
`of the electrode to ground
`
`+ In a self-capacitance sensor, each electrode is measured
`individually
`
`No Touch CS
`
`Source: The author
`
`SID DISPLAY WEEK ‘14
`
`
`
`The Problem with Self-Capacitance
`
`°2° Touches that are diagonally separated produce
`two maximums on each axis (real points & ghost points)
`
`4 Ghost points = False touches positionally related to real touches
`
`Self Capacitance
`
`Mutual Capacitance
`
`Ghost Points
`
`Source: Atmel
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Self-Capacitance and
`PinchlZoom Gestures
`
`°:~ Use the direction of movement of the points rather
`than the ambiguous locations
`
`X2
`
`X3
`
`X4
`
`Source: The author
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Self-Capacitance Electrode Variations
`
`lllllllllllliiil
`
`'”"‘-V..,_‘11.";_._
`
`IIIIIIIIIIIL
`
`In
`
`II I I IIII I II
`
`20 measurements
`
`5°"'°°= 3'“
`
`20 measurements
`
`+ Multiple separate pads
`in a single layer
`
`+ Rows and columns of electrodes
`in two layers
`
`+ Each pad is scanned
`individually
`
`+ Row & column electrodes are
`scanned in seguence
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Self-Capacitance
`Advantages & Disadvantages
`
`—
`
`«:0 Where it’s used
`
`+ Lower-end smartphones and feature-phones with touch
`
`0 Becoming much less common due to single-layer p-cap
`
`+ In combination with mutual capacitance to increase capability
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Self-Capacitance for Hover
`
`oz» Self-capacitance is used to produce “hover”
`
`behavior in some smartphones (in addition to
`mutual-capacitance for contact-touch location)
`
`+ Also used for automatically detecting glove vs. fingernail vs. skin,
`and for dealing with water on the screen
`
`Source: Panasonic
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Multi-Touch Self-Capacitance
`Using Active Guard Concept...1
`
`«:0 Guarding is a well-known technique for reducing the
`effects of electrical current leakage
`
`Leakage capacitance < 10 aF
`
`source; |=oga|e
`
`1ZI1I1ZZI1
`
`'
`
`5
`
`Active guard
`
`IIIIII I I I
`
`I
`
`/
`
`\\_________
`
`"°"
`
`SID DISPLAY WEEK ‘14
`
`
`
`Multi-Touch Self-Capacitance
`Using Active Guard Concept...2
`
`03° Another contender: zRRo
`
`R
`
`T
`
`v
`
`u
`
`I
`
`‘.
`
`'
`
`0
`
`L
`
`P
`
`/
`
`3D single-touch
`for smartphones
`
`W 3D multi-touch
`I
`for smartphones
`and tablets
`
`T
`
`SID DISPLAY WEEK ‘14
`
`ifieD
`
`
`
`Mutual Capacitance
`
`03° Capacitance between two electrodes
`
`+ Human body capacitance “steals charge” which decreases
`the capacitance between the electrodes
`
`+ In a mutual-capacitance sensor, each electrode intersection
`is measured individually
`
`Projected
`
`-in--u-n-—-_-__
`
`Glass
`
`Sense
`
`Electrode
`
`Electrode
`
`Electrode
`
`Source: The author
`
`SID DISPLAY WEEK ‘14
`
`
`
`Mutual Capacitance
`Electrode Patterns...1
`
`«:0 Rows and columns of
`
`electrodes in two la ersy
`
`«z» In the real world...
`
`+ “Bar and stripe”, also called
`“Manhattan” or “Flooded-X”
`
`(LCD noise self—shie|ding)
`
`Iluuuulr
`
`IIIIIIIIIIIL
`
`lllllllllllliim
`
`11 x 9 = 99 measurements
`
`Source: 3M
`
`I
`
`| I I | I Source:Cypress
`
`X4
`
`10=40
`
`measurements
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Mutual Capacitance
`Electrode Patterns...2
`
`0:0 Interlocking diamond pattern
`with ITO in “one layer” with bridges
`
`4.5 mm t3(pica|
`xxxxxxxxxxxxxxxxx
`xxxxxxxxxxxxxxxxx
`iXf>()(,>()(XX)()()(.[X)(>()(j>()( -
`
`xxxxxxxxxxxxx,‘%xf
`;><j>(,x;x;><:)<[>(f>(,)<lxax x><iXX5<fx._
`
`"“”“”"
`Wire or no
`
`xxxxxxxxxxxxxxxxx
`xxxxxxxxxxxxxxxxx
`xxxxxxxxxxxxxxxxxl
`
`Source: 3M
`
`SID DISPLAY WEEK ‘l4
`
`Source: The author
`
`
`
`More On Mutual Capacitance...1
`
`«to BTW, there isn't just one mutual capacitance...
`
`//V
`
`\\‘
`
`SID DISPLAY WEEK ‘l4
`
`Source: Cypress
`
`
`
`More On Mutual Capacitance...2
`
`°:~ And there are more capacitors than just the Cm’s...
`
`Finger
`Equivalent
`
`Sensing Signal
`
`Source: ELAN, modified by the author
`
`SID DISPLAY WEEK ‘l4
`
`22
`
`
`
`More On Mutual Capacitance...3
`
`——— «
`
`:0 Where it’s used
`
`+ Mid & high-end smartphones, tablets,
`Ultrabooks, AiOs, commercial products
`
`0 Standalone self-capacitive is becoming increasingly rare
`in consumer electronics (except for buttons)
`
`# With “true single-layer” sensors in low-end smartphones
`
`SID DISPLAY WEEK ‘l4
`
`
`
`
`
`Mutual Capacitance
`Electrode Patterns...4
`
`02° And so does this unusual diamond pattern...
`
`4 102, 106, 108, 210
`
`0 Drive (X) electrodes
`
`4 114 & 202
`
`0 Sense (Y) electrodes
`
`4 110
`
`o Bridges
`
`4 120 & 230
`
`o Dummy (floating) ITO
`
`4 200 & 206
`
`0 Optional dummy ITO
`
`4 212
`
`0 Blank (no ITO)
`
`Source: STMicro
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Mutual Capacitance
`Electrode Patterns...5
`
`03° Claimed advantages of this particular
`pattern over traditional interlocking diamond
`
`+ Reduction in sense electrode area reduces LCD noise pickup
`
`+ “Finger projections” (0.1 - 0.2 mm) increase the perimeter of
`interaction between drive and sense electrodes, which
`
`increases sensitivity
`
`+ Linearity is improved due to more uniform coupling across channels
`
`+ Floating separators aid in increasing the fringing fields, which
`increases sensitivity
`
`SID DISPLAY WEEK ‘14
`
`
`
`Mutual Capacitance
`Electrode Patterns...6
`
`»:~ Holy Grail: True single-layer mutual capacitance sensor
`
`0:» “Caterpillar” pattern
`
`O Everybody’s single-
`layer patterns are
`proprietary
`
`+ Requires fine
`patterning, low sheet
`resistance & low
`
`visibility
`
`O Benefits: Narrow
`
`borders, thin stack-
`
`ups, lower cost, can
`reliably handle 2-3
`touches
`
`Source: Synaptics
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Mutual Capacitance
`Electrode Patterns...7
`
`»:~ ELAN’s caterpillar pattern
`
`x1
`
`x2
`
`
`
`Mutual Capacitance
`Electrode Patterns...8
`
`°:~ An alternative true single-layer pattern from ELAN
`
`+ This is a very small portion
`of a much larger sensor
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Controllers
`
`92* Architecture
`
`02° Touch Image Processing
`
`0% Key Characteristics
`
`N Signal-to-Noise Ratio
`
`° Noise Management
`
`Innovation Areas
`
`02° Suppliers
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Mutual Capacitance
`Touch System Architecture
`
`Sense
`E'9¢t"°d95
`
`Analog Front-
`End (AFE)
`
`Analog-
`to-Digital
`Converter
`(ADC)
`
`Digital
`Signal
`Processor
`(osp)
`
`Electrodes
`
`Capacitive Nodes
`
`Host
`
`Interface
`
`Touch Sensor
`
`Touch Controller
`
`Source: The author
`
`+ Making X*Y measurements is OK, but it's better
`to measure the columns simultaneously
`
`+ Controllers can be ganged (operate in a
`master-slave relationship) for larger screens
`
`SID DISPLAY WEEK ‘14
`
`
`
`Touch Image Processing
`
`Raw data including n0iSe
`
`Filtered data
`
`Gradient data
`
`Touch region coordinates
`and gradient data
`
`“1 0 fingers,
`2
`
`sf:
`
`a n
`
`x-7070704 -‘-
`a=9w 333
`x-41729, y-33: saaeen
`
`"
`
`321230
`
`3 others
`
`17
`
`_ fl ;
`:=?90 V8 y=5’O I56960
`
`Source: Apple Patent Application #2006/0097991
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Key Controller Characteristics...1
`
`«to Node count (x channels + y channels)
`
`+ Given typical electrode spacing of 4.5 to 5 mm, this determines
`how large a touchscreen the controller can support (w/o ganging)
`
`«to Scan rate
`
`§ Frames per second (fps) — faster reduces latency for a better UX
`
`+ Windows logo requires 100 fps; Android is unspecified
`
`0:. Signal-to-noise ratio (SNR)
`
`+ More info on upcoming slides
`
`«to Operating voltage & current
`
`+ OEMs continue to request lower-power touchscreen systems
`
`+ Win8 “Connected Standby” is a significant influence
`
`«:0 Internal core (microIDSP)
`
`O Varies from small 8-bit micro to ARM-7 or higher
`
`SID DISPLAY WEEK ‘l4
`
`33
`
`
`
`Key Controller Characteristics...2
`
`03° Number of simultaneous touches
`
`+ Windows Logo requires 5 (except AiO = 2); Android is unspecified
`
`+ Market trend is 10 for tablets and notebooks
`
`«to Support for unintended touches
`
`+ “Palm rejection”, “grip suppression”, etc.
`
`+ Rarely specified, but critically important
`
`+ For a 22" screen, even 50 touches isn’t too many in this regard
`
`do Amount of “tuning” required
`
`4 Never specified — more info on upcoming slide
`
`SID DISPLAY WEEK ‘14
`
`
`
`Signal-to-Noise Ratio (SNR)...1
`
`oz» SNR = Industry-standard performance metric
`
`for p-cap touchscreen systems
`
`§ However, no standard methodologies exist for measuring,
`calculating, and reporting SNR
`
`+ The two components (signal & noise) depend heavily on
`the device under test
`
`«:0 Noise from displays (LCDs & 0LEDs) and from
`USB chargers is spiky - it doesn’t have a normal
`(Gaussian) distribution — and spikes create jitter
`
`4 Yet marketers typically specify SNR in the absence of noise,
`using the RMS noise (standard deviation) of analog-to-digital
`convertors (ADCs)
`
`+ With Gaussian noise, you can multiply the RMS noise by 6 to
`calculate the peak-to-peak noise with 99.7% confidence
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Signal-to-Noise Ratio (SNR)...2
`
`°:~ Typical system (raw ADC data, no digital filters applied)
`
`Source: Cypress
`(modified by the author)
`
`3 2‘
`
`52 8 E
`
`
`
`Signal-to-Noise Ratio (SNR)...3
`
`«:0 SNR of system in previous slide
`
`4 Cfinge, = Mean (Finger) - Mean (NoFinger)
`4 CF"-|ger = 1850 - 813 = 1037
`
`4 CNS (Standard Deviation) = 20.6 counts
`
`4 CNS (Peak-to-Peak) = Max (NoFinger) - Min (NoFinger) +1
`
`4 CNS = 900 - 746 +1 = 155 counts
`
`4 SNR (Peak-to-Peak) = 1037/155 = 6.7
`
`4 SNR (Standard Deviation) = 1037/20.6 = 49.9
`
`4 Highest SNR currently reported by marketer = 70 dB (3,162*)
`
`SID DISPLAY WEEK ‘14
`
`37
`
`inte|'
`
`* Signal amplitude ratio in dB = 20log10 (A1/A0)
`
`
`
`Noise Management...1
`
`«:0 Charger noise is common-mode
`
`+ A smartphone on a desk (not handheld) isn't grounded, so the
`entire phone moves relative to earth ground as it follows the noise
`
`4 A touching finger provides an alternative path to ground, which
`is equivalent to injecting the noise at the finger location
`
`4 The noise signal can be 10X to 100X that of the signal
`generated by the touching finger
`
`svdc
`
`5Vd
`
`C
`
`sva
`
`C
`
`5Vd
`
`“Gnd”
`
`Source: Cypress
`
`‘
`
`I
`
`. I I u
`I
`I
`f
`l
`I I I I I
`
`Can be
`as high
`as 60 V
`p-p for
`222:5;
`
`No common-mode noise
`
`Small common -mode noise
`
`Strong common-mode noise
`
`SID DISPLAY WEEK ‘14
`
`
`
`Noise Management...2
`
`°:~ Examples of charger noise spectra
`
`+ Effect of noise is false or no touches, or excessive jitter
`
`/ Narrow-band noise (charger A)
`\
`
`Wide-band noise (ohager B)
`
`L
`
`200
`
`300
`
`400
`
`Charger Noise Frequency
`
`600 kHz
`
`some: Cymess
`
`1
`
`0
`‘O
`
`a‘
`
`E 8
`
`’
`5 00
`.2
`
`E £
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Noise Management...3
`
`°:~ Variation in common-mode noise spectra in 2
`different chargers at 3 different loads
`
`No load
`
`Load 50%
`
`SID DISPLAY WEEK ‘l4
`
`‘“"‘
`
`Source: Cypress
`
`
`
`Noise Management...4
`
`03° Techniques to combat charger noise
`
`+ Multiple linear and non-linear filters
`
`+ Adaptive selection of the best operating frequency (hopping)
`
`+ Increased drive-electrode voltage
`
`0 Going from 2.7 V to 10 V increases SNR by 4X
`
`+ Many proprietary methods
`
`«to Display noise
`
`+ LCD noise is similar across the display; the high correlation of noise
`signals across all sensor signals allows relatively easy removal
`
`4 Very high noise in embedded touch can require synchronization
`of the touch controller with the LCD driver (TCON)
`
`SID DISPLAY WEEK ‘14
`
`
`
`Controller Innovation Areas
`
`«:0 More information in upcoming slides
`4 Finger-hover
`4 Glove-touch
`
`4 Pressure sensing
`4 Other touch-objects
`4 Faster response (reduced latency)
`4 Adaptive behavior
`4 Water resistance
`
`4 Software integration
`4 Automated tuning
`
`'30 More information later in this course
`
`4 Passive and active stylus support
`
`SID DISPLAY WEEK ‘14
`
`
`
`Finger-Hover...1
`
`«to There are two ways of emulating “mouseover” on
`
`a p-cap touchscreen
`
`§ Hover over something to see it change, then touch to select
`
`§ Press lightly on something to see it change, then press harder
`to select
`
`oz» The industry is moving towards hover because nobody
`has been able to implement pressure-sensing in a way
`
`that works well and that 0EMs are willing to implement
`
`4 Startup: Nextlnput
`
`o Force—sensing using an array of organic transistors where pressure
`
`changes the gate current
`
`+ Startup: zRRo
`
`o Multi-finger hover detection
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Finger-Hover...2
`
`«:0 What can you do with hover?
`
`+ Enlarge small links when you hover over them
`
`+ Make a passive stylus seem to hover like an active stylus
`
`+ Magnify an onscreen-keyboard key as you approach
`rather than after you’ve touched it, or even use a “Swipe”
`keyboard without touching it
`
`+ Preview interactive objects such as an array of thumbnails
`
`+ Use as an alternative to standard proximity detection
`
`4 Use mu|ti—finger gestures for more complex operations
`
`+ And more...
`
`SID DISPLAY WEEK ‘14
`
`
`
`Glove-Touch
`
`02° Can be accomplished by
`adding self-capacitive to
`existing mutual-capacitive
`
`+ Mutual-capacitive provides
`touch location
`
`4 Self-capacitive provides
`proximity sensing
`
`+ Glove-touch causes the finger
`to remain a constant distance
`
`above the screen; proximity
`sensing can detect that without
`the user manually switching
`modes
`
`SID DISPLAY WEEK ‘14
`
`
`
`Pressure Sensing
`
`03° Pressure-sensing is an alternative selection method
`
`+ True absolute pressure-sensing in p-cap doesn't exist today
`
`+ Some (including Microsoft) believe that “touch lightly to view
`choices then press to select” is more intuitive than hover
`
`o It has never been implemented successfully in a mobile device
`
`> Blackberry Storm (2 models!) failed due to terrible implementation
`
`> Nissha/Peratech (QTC) collaboration never made it into mass—production
`
`+ Multiple startups are working on smartphone pressure-sensing
`
`o Nextlnput
`
`) Uses an array of pressure-sensitive organic transistors under the LCD
`
`0 FloatingTouch
`
`> Mounts the LCD on pressure-sensing capacitors made using a 3M material
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Other Touch Objects
`
`oz» You will soon be able to touch with a fine-tipped (2 mm)
`passive stylus, long fingernails, a ballpoint pen, a #2
`pencil, and maybe other objects
`
`+ This is being accomplished through higher signal-to-noise
`(SNR) ratios
`
`o Much of this improvement may come from enhancing the controller
`
`analog front-end in addition to focusing on the digital algorithms
`
`+ This enhancement to the UX will be the end of “finger-on|y” p-cap
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Faster Response
`
`ozo Make touch more natural by reducing latency
`
`4 The shorter the time is between a touch and the response,
`the better the user feels about the touch system
`
`c If an object lags behind your finger when you drag it, or ink lags
`
`behind a stylus when you’re drawing, it doesn’t feel real
`
`0 Latency today is typically 75-100 ms;
`studies have shown that humans
`
`need less than 10 ms for comfort
`
`0 Synaptics has addressed the problem
`by creating a direct path between the
`touch controller and the TCON to
`
`allow limited instant screen updates
`
`o Tactual Labs (startup) has a method
`
`of reducing latency to just a few
`milliseconds
`
`SID DISPLAY WEEK ‘l4
`
`Android
`lag!
`
`Source: Gigaom.com
`
`
`
`Adaptive Behavior: Noise Immunity
`
`»: Adaptive noise-management by N-Trig
`
`SID DISPLAY WEEK ‘14
`
`
`
`Water Resistance...1
`
`«:0 The basic concept is combining self-capacitive and
`mutual-capacitive sensing (again)
`
`Water drops on the screen
`
`source: ELAN
`
`Self Y
`
`SID DISPLAY WEEK ‘l4
`
`50
`
`intel'
`
`Water is not detected
`
`Water is detected in
`
`in self-capacitive mode
`
`mutual—capacitive mode
`
`
`
`Water Resistance...2
`
`oz» A large amount of water with single-touch
`
`15:5ooooooonoouoooooooco7aouoomoooooooooooo:(
`
`lfoazxoooooonnooooooooounooooaoauooooooooooooojt
`
`S°U"3e3ELAN
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Water Resistance...3
`
`«to A large amount of water with two touches
`2
`3
`4
`5
`6
`7
`8
`3
`
`‘
`
`'
`2' I H
`
`MN
`'65")?
`
`‘W-Self Y
`;
`£7;
`
`aoocnoooooneoucomooncowoosnoosooofi
`
`-
`
`«««-n«»===
`
`-a9s5o|IiIm;oooo ouocuaou omo oouof
`"
`,
`(Mk
`LXMJ}
`
`(HI)
`
`sill)
`
`(III?
`
`till.) CIIIJ
`
`'
`
`-
`,
`-
`
`‘MK MIN All
`
`:.
`
`SID DISPLAY WEEK ‘l4
`
`intel
`
`«
`
`:oooc'cooo:anoojouoo'oooo:oooo ooooioooo
`
`oooo
`
`Sou[ce;E|_AN
`
`
`
`Software Integration
`
`«to Make more resources available to the touch controller
`
`+ Run touch algorithms on the GPU instead of the controller micro
`
`o Algorithm-writers can take advantage of much larger resources on
`
`the host device (MIPS and memory)
`
`>
`
`o Algorithmic code is easier and faster to change when it’s in a “driver”
`than when it's in firmware in an ASIC
`
`> Most touch-controller suppliers never change the firmware in the
`touch controller once it ships in a device; N—Trig is the sole exception
`
`0 Cost-reduction by elimination of one micro
`
`> Even more cost reduction for large screens by elimination of slave chips
`
`0 Something similar to this has already been done in NV|D|A’s
`“Direct Touch”, but it hasn’t been widely used in actual devices
`
`SID DISPLAY WEEK ‘14
`
`
`
`Automated Tuning
`
`«:0 For true “touch everywhere”, p-cap has to become
`like resistive: Just slap it on and you’re done
`
`+ We're far from that point today
`
`+ Atmel says that the typical first integration of a p-cap touch-panel
`into a new product takes one full day of tweaking up to 200
`individual parameters
`
`+ That badly needs to be automated so that small commercial
`product-makers have easier access to p-cap
`
`SID DISPLAY WEEK ‘14
`
`
`
`P-Cap Controller Suppliers
`
`03° In order by estimated 2013 revenue
`
`Broadcom A Ie
`
`Ts T°'° 7 ‘3°%’
`"“°°°””‘ 2°’
`ab°“t 85 /" °f
`total revenue
`
`China & Taiwan
`
`FocalTech
`
`ELAN
`
`And a few others...
`+ AMT
`+ Avago
`EET:
`ms + pixel,
`..
`8'8
`Tawvan
`+ Slllcon Labs
`
`+ STMicro
`
`+ Weltrend
`
`SID DISPLAY WEEK ‘14
`
`
`
`02° Substrates
`
`020 Structures
`
`020 Sheet vs. Piece Method
`
`020 More on OGS
`
`020 Glass Strengthening
`
`020 Surface Treatments
`
`020 ITO Index Matching
`
`020 Suppliers
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Sensor Substrates...1
`
`03° ITO film substrates are usually PET‘ or COP2
`
`+ Thickness has dropped from 100 pm to 50 um
`
`+ Lowest practical ITO sheet resistivity is currently ~100 (2/1:
`
`«to ITO glass substrates
`
`+ Standard thickness for GG is 0.33 mm and 0.4 mm
`
`4 Some makers have developed a thinning process (like for LCDs)
`that reduces glass thickness to 0.2 mm
`
`+ Coming and AGC have developed 0.1 mm glass but it hasn’t
`been used in volume sensor production yet
`
`+ Lowest practical ITO sheet resistivity on glass is ~50 0/1:
`
`1 = Polyethylene Terephthalate
`2 = Cyclic Olefin Polymer
`
`SID DISPLAY WEEK ‘l4
`
`
`
`570°C
`
`No known effect
`
`nG
`
`)v
`
`coo$
`
`Thicker
`
`Heavier
`
`ood
`
`Chemical, heat,
`ion-exchange
`
`Sensor Substrates...2
`
`oz» PET film versus glass
`
`Glass Transition Temperature 70°C
`
`Aging Effects
`
`Transparency
`Resolution Capability
`Stacku
`
`Weight
`
`Moisture Resistance
`
`Lamination Yield
`
`Mechanical Strengthening
`
`Yellowing, curling,
`surface deformation
`
`85%
`
`10-30 pm
`Thinner
`
`Lighter
`
`Good
`
`Cost
`
`$ was < lass
`
`SID DISPLAY WEEK ‘14
`
`
`
`Sensor Structures...1
`
`~:~ Sensor structure abbreviations (for reference)
`
`Cover-lass or o lastic or sa o hire
`
`Cover-glass, or sensor-glass with ITO on one side, or
`c lain o lass for film lamination
`
`G G
`
`GG
`
`Cover-lass + one sensor- lass without ITO location
`
`GGG Cover-lass + two sheets of sensor- lass rare
`
`G#
`
`G1 F
`GFF
`
`# = Number of ITO layers on one side of sensor-glass
`G2 = “One Glass Solution” = OGS = SOC = SOL, etc.
`F = Sensor-film with ITO on one side, laminated to glass
`FF = Two sensor-films, laminated to lass
`
`1 = Two ITO layers on one side of sensor-film,
`laminated to glass (also called GF-Single)
`2 = One ITO layer on each side of sensor-film,
`laminated to glass (also called GFxy with metal mesh)
`ITO on one side of substrate (single-sided);
`usually includes metal bridges for Y to cross X
`ITO on both sides of substrate double-sided
`
`F1 = Single-sided sensor-film on top of CF glass;
`T = Transmit (drive) electrodes on TFT glass
`(LG Disp|ay’s hybrid in—cel|/on-cell)
`
`SID DISPLAY WEEK ‘14
`
`59
`
`intel‘
`
`
`
`Sensor Structures...2
`
`03° Glass-only structures
`
`Structure Names
`
`GGG
`
`GG or G-SITO
`
`GG , G-DITO or G1G
`
`OGS or SOC
`
`Comments
`
`Single ITO layer on
`
`Single ITO layer
`
`ITO layer on each
`
`Single ITO layer
`
`each piece of glass;
`Obsolete
`
`with bridges
`
`side of 1 glass; or ITO
`on one side of 2 - lass
`
`with bridges
`
`Example Products
`
`Kindle Fire,
`
` B&N Nook;
`
`Nokia Lumia 800
`
`iPhon&1; iPad-1
`
`(GG); LenovoAiOs
`
`G1G
`
`Google Nexus 4/7;
`
`Xiaomi2;
`
`Nokia Lumia 920
`
`> SITO = Single-sided ITO layer; usually means there’s a bridge
`
`) DITO = Double-sided ITO layer (Apple patent)
`
`> OGS = One Glass Solution (sensor on cover-glass)
`
`> SSG = Simple Sensor Glass (OGS without cover—glass shaping & finishing)
`
`SID DISPLAY WEEK ‘14
`
`intel’
`
`
`
`Sensor Structures...3
`
`°:~ Glass-and-film structures
`
`Structure Names
`
`G1 F
`
`Single ITO layer on
`
`glass; single ITO
`la er on film
`
`Example Products
`
`Many Samsung
`
`products in 2013;
`Microsoft
`
`Surface RT
`
`> Why would a touch-module maker use a sensor structure
`that requires having both glass- and film-handling equipment?
`
`» One reason is that there was a shortage of ITO film in 2013
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Sensor Structures...4
`
`«to Film-only structures
`Structure Names
`
`Comments
`
`Bare glass and two
`single-sided ITO films;
`performance is better
`than GF1
`
`GF2 or DITO-Film
`
`Bare glass and one
`double-sided
`
`Bare glass with true
`single-layer complex
`pattern on film
`
`Apple iPads; next
`iPhone if Apple can’t get
`. ood ield on in—ceIl
`
`l-Vlany |ow—end
`smartphones, especially
`in China
`
`GF Triangle
`Bare glass with true
`single-layer triangle
`pattern on film
`(e.g., "backgammon")
`Low-end products with
`"gesture touch’, not
`multi-touch
`
`> Single-layer caterpillar pattern is used to support “rea|” multi-touch with 2-3
`touches, typically in a smartphone (that's not enough touches for a tablet)
`
`> Sing|e—layer backgammon pattern is used to support “gesture touch” on
`low-end devices, i.e., the ability to detect pairs of moving fingers but not
`always resolve two stationary touches
`
`SID DISPLAY WEEK ‘14
`
`62
`
`intel
`
`
`
`Sensor Structures...5
`
`°:~ Why do touch-module makers choose one structure
`over another?
`
`+ Transmissivity
`
`+ Thickness & weight
`
`4 Border width due to routing
`
`# Cost & availability of ITO film or deposition
`
`4 Lamination experience & yields
`
`+ Existing equipment and/or method experience
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Sensor Structure by Application
`
`Smartphones
`
`Tablets & Notebooks
`
`A||—in-Ones
`
`GF1/Sinle-La er
`
`Data based on DispIaySearch's “Q1-2014 Quarterly Touch-Panel
`Market Analysis Report”, with adjustments by the author
`
`SID DISPLAY WEEK ‘14
`
`
`
`Sheet vs. Piece Method...1
`
`(Wintek Sheet Example - OGS)
`
`SID DISPLAY WEEK ‘14
`
`55
`
`Source: Wintek
`
`
`
`Sheet vs. Piece Method...2
`
`(Wintek Piece Example - Discrete)
`
`SID DISPLAY WEEK ‘l4
`
`55
`
`Source: Wintek
`
`
`
`More On OGS
`
`oz» One-Glass Solution (OGS)
`
`4 Also called “touch on |ens” (TOL), “sensor on cover” (SOC),
`“direct patterned window” (DPW) and many other names
`
`4 Advantages
`
`o Eliminates a fourth sheet of glass (G-DITO), making the end-product
`
`thinner and lighter
`
`0 Competitive weapon against embedded touch from LCD suppliers
`
`4 Disadvantages
`
`o Requires close cooperation with cover-glass makers, or increased
`vertical integration (preferable)
`
`o Yields are lower (more complex operations)
`
`0 Bendable cover glass can affect touch performance
`
`0 Harder to shield touchscreen from LCD noise
`
`4 Note: There is no generic name (yet) for touch sensors built on the
`cover-glass without direct ITO deposition (“OGS-type”)
`
`SID DISPLAY WEEK ‘14
`
`57
`
`intel
`
`
`
`Glass Strengthening
`
`oz» Heat strengthened
`
`+ Less-rigorous version of fully tempered; does not “dice” when
`
`broken; 2X as strong as standard glass
`
`0:» Fully tempered
`
`§ Uses heat; requires glass > 3 mm, so not used for consumer
`touchscreens; glass “dices” when broken (think auto windows);
`4X to 6X as strong as standard glass
`
`«:0 Chemical strengthened (CS)
`
`4 Uses ion-exchange in a salt bath; best for glass < 3mm; glass does
`NOT “dice” when broken; 6X to 8X as strong as standard glass
`
`«:0 High ion-exchange aluminosilicate glass
`
`0 6X to 8X as strong as standard glass (same as CS glass)
`
`4 Coming Gori||a®, Asahi Dragontrai|""', Schott XensationT""
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Sensor Surface Treatments...1
`
`oz» Historically most common treatment is anti-glare (AG)
`
`+ Changes specular reflection into diffuse reflection
`
`+ Used mostly for commercial & enterprise, not consumer (“g|ossy”)
`
`+ Three methods, roughly equal cost
`
`0 Chemical etching
`
`0 Application of sol-gel containing silica particles
`
`o Mechanical abrasion
`
`0 Level of anti-glare can be very little to a lot
`
`03° Anti-fingerprint (AF) treatment is rapidly growing
`
`+ Many different forms (spray-on, rub-on, sputter, etc.); also
`called “anti-smudge” (AS)
`
`0 Demand is increasing
`
`+ Cost is dropping (currently ~$8.50/m2)
`
`SID DISPLAY WEEK ‘l4
`
`59
`
`
`
`Sensor Surface Treatments...2
`
`oz» Anti-reflection (AR) treatment is still a problem
`
`4 Reduces specular reflection to range of 2% to 0.4%
`
`4 Durability is typically < 1 year
`
`4 |t’s expensive (currently ~$34.50/m2)
`
`4 Yet it’s really important for outdoor viewing, particularly of
`consumers’ glossy screens (ideal is AF+AR = ~$43/m2)
`
`~30 Other coatings are available but less common
`
`4 Anti-corruption (allows permanent Sharpie ink to be wiped off)
`
`4 Anti-microbial/anti-bacteriaI (AM/AB, for healthcare applications)
`
`4 Hard coating (can be made up to 9H for glass-like anti-scratch)
`
`4 Anti-stiction (reduces finger-sticking friction)
`
`4 Anti-crack coating (increases durability at lower cost than Gorilla
`glass; uses atomic layer deposition [ALD])
`
`SID DISPLAY WEEK ‘l4
`
`
`
`ITO Refractive-Index Matching
`
`03° Reduce the reflectivity of ITO by compensating for the
`difference in index of refraction of ITO vs. glasslPET
`
`~:~ Limited to 2 layers on PET; more can be used on glass
`
`5 Alternating layers of material with low and high refractive index
`
`+ Layer thicknesses (typically between ‘A and % of the wavelength
`of light) are chosen to produce destructive interference in reflected
`light, and constructive interference in transmitted light
`
`no (Rl = ~2.o)l
`
`TiO2 (RI = 2.43)T
`
`SiO2 (RI = 1.45)
`
`or PET (RI = 1.65)
`
`Source: The author
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Sensor Suppliers
`
`oz» Many touch-module makers manufacture their
`
`own sensors
`
`+ The remainder are made by the following companies,
`in order by estimated 2013 revenue
`
` — Jaan
`
`A,,dat,eastmo,e
`, Laibao(C,,i,,a,
`
`jna
`
`mm
`
`SID DISPLAY WEEK ‘l4
`
`
`
`ITO-Replacement Materials
`
`9:9
`
`9:9
`
`9:9
`
`9:9
`
`9:9
`
`9:9
`
`‘9
`
`'|ver Nanowires
`
`arbon Nanotubes
`
`onductive Polymers
`
`SID DISPLAY WEEK ‘l4
`
`
`
`ITO Replacements...1
`
`«to Why replace ITO?
`4 Costly to pattern & needs high temperature processing
`4 Highly reflective (IR = 2.6) & tinted yellow; brittle & inflexible
`4 NOT because we’re going to run out of it!
`
`«to Replacement material objectives
`4 Solution processing (no vacuum, no converted LCD fab)
`4 Better performance than ITO (transmissivity & resistivity)
`4 Lower material & process cost than ITO
`
`«:0 Five replacement candidates
`4 Metal mesh
`
`4 Silver nanowires
`
`4 Carbon nanotubes
`
`4 Conductive polymers
`4 Graphene
`
`SID DISPLAY WEEK ‘l4
`
`
`
`ITO Replacements...2
`
`~30 ITO-replacement materials are having a definite
`market impact - 11% in 2014!
`
`4 See the latest IHS market report on non-ITO films
`Hon ll J lllm «Market ihdlt‘ by him lyue (2014!
`
`Nomofilm
`11*
`
`i
`
`*
`
`a
`
`0 Ag halide is simply
`another method of
`
`making a silver mesh,
`so the mesh total is
`
`85% vs. 15% for
`
`nanowire
`
`+ The value is performance and cost
`
`0 Both unit cost and CAPEX
`
`SID DISPLAY WEEK ‘14
`
`
`
`Metal Mesh...1
`
`oz» Metal mesh is shipping in touchscreens, and it’s
`looking very promising!
`
`~:~ Brief history of first-movers
`
`O MNTech in Korea was the first to ship metal-mesh at the
`end of 2012 — but their factory burned down
`
`4 Atmel (partnered with CIT in the UK) was the second to ship metal-
`mesh (XSense T”) for a smartphone and a 7" tablet in 1H-2013
`
`4 FujiFi|m started production of their silver-halide-based
`metal-mesh product in 2Q—2013
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Metal Mesh...2
`
`4-5 mm sense electrode (bottom surface)
`
`\
`
`_—
`
`’
`
`\-
`
`Photo by Unipixel,
`annotation by
`the author
`
`.
`
`'
`
`SID DISPLAY WEEK ‘14
`
`4-6 pm wide
`conductors
`
`with spacing
`
`of 100-400 um
`
`4-5 mm
`
`drive
`
`electrode
`
`(top surface)
`
`Intentional
`
`gaps in lines
`
`i@
`
`
`
`Metal Mesh...3
`
`oz» Metal mesh has significant advantages
`
`+ Patterning via roll-to-roll printing allows both operating and
`capex cost to be very low — it’s going to beat both Iitho and laser!
`
`0 Electrodes and border connections are printed simultaneously,
`
`which allows borders as narrow as 3 mm (typically 9 mm with ITO)
`
`+ Sheet resistivity is much lower than ITO (under 10 ohmslsquare)
`
`o Reduces p-cap charge time, which allows larger touchscreens
`
`4 Transparency is better than ITO
`
`4 Mesh pattern creates electrical redundancy, which improves yields
`
`+ Highly flexible — bend radius typically 4 mm
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Metal Mesh...4
`
`°:~ 0-film is the “800-pound gorilla” of metal mesh!
`
`+ Largest touch-module maker in China, #3 globally
`
`+ Like “the TPK of film”; innovative and aggressive
`
`source:0-film
`
`oz» New roll-to-roll printing method
`
`+ “Hybrid printing” or “micro-imprinting”
`
`Cross-section of
`
`embedded metal line
`
`Source:O—fIlm
`
`Impressions
`\
`
`Sflver nan°'
`Partide
`
`UV cure
`A
`
`Source: The author
`
`SID DISPLAY WEEK ‘l4
`
`
`
`Metal Mesh...5
`
`oz» O-film technical details
`
`+ Additive process with little waste
`
`4 < 2 pm line width
`
`+ < 10 (2/1:
`
`4 Randomized mesh design (one method of eliminating moirés)
`
`§ Top surface of embedded metal line is blackened & sealed
`
`+ Embedded metal reduces haze and eliminates peel-off
`
`+ Producing > 1.5M touch sensors per month (size not stated)
`
`~30 O-film’s success makes visible a developing aspect of
`
`the ITO-replacement business
`
`+ Avertical|y—integr
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