Fundamentals of Touch Technologies

Fundamentals of
Touch Technologies
Geoff Walker
Senior Touch Technologist
Intel Corporation
v1.1
Updated October, 2013
1
v1.3
File Download: www.walkermobile.com/Touch_Technologies_Tutorial_Latest_Version.pdf
Agenda…1
 Course structure

Topic Allocation
Introduction 6%
Main Content 88%
Capacitive – 1 32%
Resistive – 2 9%
Acoustic – 3 8%
Optical – 4 20%
Embedded – 5 13%
Other – 6 2%
Active Stylus – 7 6%
Software – 8 10%
Conclusions 6%
TOTAL 100% 100%

 6 fundamental touch technologies with ~20 types
2
Agenda…2
 Admin

 Introduction to Touch Technologies
 Capacitive (1)
 1A - Projected Capacitive (P-Cap)
 ITO Replacement Materials
 1B - Surface Capacitive
 Resistive (2)
 2A - Analog Resistive
 2B - Analog Multi-Touch Resistive (AMR)
 2C - Digital Multi-Touch Resistive
 Acoustic (3)
 3A - Surface Acoustic Wave (SAW)
 3B - Acoustic Pulse Recognition (APR by Elo Touch Solutions)
 3C - Dispersive Signal Technology (DST by 3M Touch Systems)
3
Agenda…3
 Optical (4)
 4A - Traditional Infrared
 4B - Waveguide Infrared (DVT by RPO)
 4C - Multi-Touch Infrared
 4D - Camera-Based Optical
 4E - Planar Scatter Detection (PSD by FlatFrog)
 4F - Vision-Based
 Embedded (5)
 LCD Architecture Refresher & Terminology Review
 Hybrid In-Cell Mutual Capacitive for IPS & Non-IPS LCDs
 On-Cell P-Cap
 In-Cell Light-Sensing
 In-Cell “Pressed” Capacitive
 In-Cell Voltage-Sensing
 In-Cell Self-Capacitive

 Embedded Touch Issues
4
Agenda…4
 Other Touch Technologies (6)
 Force-Sensing
 Active-Stylus Technologies (7)
 Electromagnetic Resonance (EMR) Stylus
 P-Cap Stylus
 Other Active Stylus Technologies
 Software (8)
 Multi-Touch
 Operating-System Application-Development Support
 Middleware
5
Agenda…5
 Conclusions
 Touch Technology vs. Application
 Usability, Performance, and Integration Characteristics
 Touch Technology Primary Advantages and Flaws
 Predictions for the Future
 Suggested Reading on Touch
 Recommended Conferences and Trade Shows on Touch
6
Introduction
Source: Gizmodo
7
(Michelangelo's "The Creation Of Adam“, in the Sistine Chapel, 1511)
File Download: www.walkermobile.com/Touch_Technologies_Tutorial_Latest_Version.pdf
Two Basic Categories of Touch
 Opaque (non-transparent) touch

 Dominated by the controller chip suppliers
● Atmel, Cypress, Synaptics, etc.
● One technology (projected [self] capacitive)
● Sensor is typically developed by the device OEM
 Notebook touchpads are the highest-revenue application
● Synaptics, Alps and ELAN have the majority of the market
● Sensors are all two-layer projected capacitive
 There is no further discussion of opaque touch in this course
 Transparent touch on top of a display
 Dominated by the touch module manufacturers
(150+ worldwide)
 6 fundamental technologies with ~20 types
8
Overall Touchscreen Market
2012-2017
Source: DisplaySearch Quarterly Touch-Panel Market Analysis Report (June 2013)
1.3
1.6
1.8
2.1
2.3
2.4
0.0
0.5
1.0
1.5
2.0
2.5
3.0
2012 2013 2014 2015 2016 2017

$24.2
$34.2
$39.1
$43.4
$46.0
$46.2
$0.0
$5.0
$10.0
$15.0
$20.0
$25.0
$30.0
$35.0
$40.0
$45.0
$50.0
$55.0
2012 2013 2014 2015 2016 2017
Units (Billions) Revenue ($Billions)
2012-2017
CAGR = 13.0%
2012-2017
CAGR = 13.8%
Touch in 2007 was 308M units & $1.3B…
9
Touchscreen Market 2007-2017
by Technology (Units)
% of Units Shipped
Source: DisplaySearch Touch-Panel Market Analysis Reports 2008-2013

10
4%
13%
23%
41%
62%
63%
58%
59%
60%
61%
63%
93%
85%
75%
57%
28%
20%
16%
13%
11%
9%
8%
8%
9%
12%
15%
15%
14%
14%

6%
11%
10%
11%
12%
13%
3%
2%
1%
3%
2%
2%
3% 3%
3%
3%
3%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2007A 2008A 2009A 2010A 2011A 2012A 2013F 2014F 2015F 2016F 2017F
Other Technologies
In-Cell (P-Cap)

On-Cell (P-Cap)
Resistive
P-Cap
Touch Technologies
by Size & Application







#






Touch Technology
Mobile
(2” – 17”)
Stationary
Commercial
(10” – 30”)
Stationary
Consumer
(10” – 30”)
Large-Format
( >30”)

1A Projected Capacitive M M L L
1B Surface Capacitive M
2A Analog Resistive M M L
2B Analog Multi-Touch Resistive (AMR) E E
2C Digital Multi-Touch Resistive (DMR) E
3A Surface Acoustic Wave (SAW) M L
3B Acoustic Pulse Recognition (APR) E L
3C Dispersive Signal Technology (DST) L
4A Traditional Infrared (IR) M M
4B Multi-Touch Infrared E E E E
4C Camera-Based Optical M M
4D Planar Scatter Detection (PSD) E
4E Vision-Based (In-Cell Optical) E
5 Embedded (In-Cell/On-Cell Capacitive) M E
6 Force Sensing E

11
M = Mainstream L = Low-volume E = Emerging
Touch Technology
Transparent
Conductor (ITO)
No Transparent
Conductor
Patterned
Surface capacitive
Low
Resolution
Analog & digital
multi-touch
resistive (AMR

& DMR)
Projected
capacitive
Embedded
(In-cell &
on-cell)
Dispersive Signal
Technology (DST)
Camera-based
Force sensing
Vision-based
Surface acoustic wave (SAW)
Acoustic Pulse
Recognition (APR)
Analog resistive
Traditional infrared (IR)
Planar scatter detection (PSD)
Touch Technologies
by Materials & Process
= Emerging or Low-Volume
= Mainstream
Multi-touch infrared
Continuous
Edge Conductors
High
Resolution
No Edge
Conductors
12
A Simple Touch Isn’t Simple…1

13
 Touch classification from the University of Toronto
Source: Daniel Wigdor
Example:
iPhone/iPad
A Simple Touch Isn’t Simple…2
14
 It’s far more complex than just “how many touches?”
The Breadth vs.
Depth Problem
Re-design software
for each platform’s
capabilities
(narrow breadth,
deep functionality)
Design software
once for common
capabilities
(wide breadth,
limited functionality)
?
Touch Is An Indirect Measurement
15
Touch Technology What’s Being Measured
Projected capacitive,
Embedded (capacitive)
Change in capacitance
Surface capacitive Current
Resistive (all forms) &
Embedded (voltage-sensing)

Voltage
Surface acoustic wave Ultrasonic wave amplitude
Acoustic Pulse Recognition &
Dispersive Signal Technology
Bending waves
Infrared & camera-based (all forms),
Planar Scatter Detection
Absence or reduction
of light
Vision-based Change in image
Embedded (light-sensing) Presence of light
Force sensing Force

The ideal method of sensing
touch has yet to be invented!
 This is one reason why there are so many technologies
16
 Projected Capacitive (P-Cap)
 ITO-Replacement Materials
 Surface Capacitive
Capacitive Touch Technologies
File Download: www.walkermobile.com/Touch_Technologies_Tutorial_Latest_Version.pdf
Projected
Capacitive
Source: Apple
17
File Download: www.walkermobile.com/Touch_Technologies_Tutorial_Latest_Version.pdf
Projected Capacitive…1
 iPhone, iPad and other products using projected
capacitive (p-cap) have set the standard for touch

in SEVERAL BILLION consumers’ minds
 Multiple simultaneous touches
 Extremely light touch
 Flush surface (zero-bezel)
 Excellent optical performance
 Reliable and durable
 Fully integrated into the user
experience – effortless & fun
Source: TabletPC2.com
18
Projected Capacitive…2
 Self-capacitance principle
Source: 3M
19
Projected Capacitive…3
 Self-capacitance electrode variations
Source:
3M
 Multiple separate pads
in a single layer
 Each pad is scanned
individually
 Rows and columns of electrodes
in two layers
 Row & column electrodes are
scanned in sequence
20
Self Capacitance
Mutual Capacitance
Projected Capacitive…4

 The problem with self-capacitance
Source: Touch International
 Touches that are diagonally separated produce
two maximums on each axis (real points & ghost points)
● Ghost points: False touches positionally related to real touches
No
Ghost
Points!
21
Projected Capacitive…5
 Mutual-capacitance principle
Source: 3M
Touch
No touch
“Projected”
electric field
22
Projected Capacitive…6
 Mutual capacitance example (Apple iPhone)
 Output is an
array of
capacitance
values for each
X-Y
intersection
Source: Apple
Source: The Author
23
Projected Capacitive…7
Raw data including noise

Touch regions
Touch region coordinates
and gradient data
Filtered data
Gradient data
Source: Apple Patent Application #2006/0097991
“10 fingers,
2 palms
and
3 others”
24
Projected Capacitive…8
 “Interlocking diamond” electrode configuration
25
Source: Atmel
RED
(Drive)
BLUE (Sense)
4.5 mm typical
Source: 3M