Karlheinz Blankenbacheitidaten.fh-pforzheim.de/.../displays/ed_touch_short.pdf · 2013-01-13 · D I S P L A Y L A B PFORZHEIM UNIVERSITY Blankenbach / Pforzheim Univ. / / Bachelor

D I S P L A Y L A BPFORZHEIM UNIVERSITY


Blankenbach / Pforzheim Univ. / www.displaylabor.de / Bachelor / Jan. 2013

Electronic Displays: Touch (short version) ET/IT & TI

1

Karlheinz Blankenbach

Pforzheim University, Germany

Prof. Dr. Karlheinz Blankenbach

Pforzheim University

Tiefenbronner Str. 65

D-75175 Pforzheim, Germany

Phone : +49 7231 - 28 - 6658

Fax : +49 7231 - 28 - 6060

Email : [email protected]

Web : www.displaylabor.de





2 2

• Introduction

• Touch Screen Technologies

Overview

• Application Issues

• Summary

Some slides are from Touch

Screen tutorials given by

3M, Fujitsu, Walker Mobile &

Elo TouchSystems





3 3

Touch Screens

• Easies many HMI concepts by direct input (command buttons etc.)

• Mature technologies available

• Allows easy input incl. characters and graphics e.g. smartphone

• Space saving compared to keyboard and mouse

Why ?

• Rise in some application system costs

• Reduced ambient light performance of display

• Inadequate performance of text input via stylus (is also an additional item !)

• Often more time consuming than keyboard and mouse

Why not ?





4 4

Touch Screens

Why - because it is in !

Touch is not only technology – it is also user interface driven !





5 5

Touch Screen Basics

Finger input:

- simple, no device required

- but low “resolution”

Sylus input:

- simple, high

resolution (> 50 ppi)

- stylus required

- SW for text input





6 6

Touch Screen Applications

• Point of sale (POS) in restaurants, hospitality, post offices, …

• ATMs

• Industrial/process control

• Medical equipment

• Office equipment like copiers

• Retail

• Automotive: navigation, diagnostic systems

• Personal mobile device

• Kiosks: Point of information (POI), merchandising, tourism & museums,

digital photo printing stations, …

• Ticketing & vending incl. transportation

• Gaming, amusement, …

• Telecommunication

• Web phones

• Internet terminals

• Outdoor: Gas pumps, store window applications





8 8

Touch Screen System

…includes

- Touch sensor

- Touch controller

- Software





9 9

Touch Screen System

System becomes more complex

Route the touch screen cable away

from the LCD backlight inverter





10 10

Touch Screen Cost Share

About the same price as for LCD !





11 11

• Introduction


Overview


• Summary

Analog resistive

Surface capacitive

Surface acoustic wave (SAW)

Infrared (IR)

Projected capacitive Optical

Acoustic pulse recognition

Dispersive signal technology





12 12

Touch Technologies 1/2





13 13

Touch Technologies 2/2





14 14

Analog Resistive (I)

2009





15 15

Analog Resistive (II)

Principle

‚Short„

To TS

controller





16 16

Analog Resistive (III)

Spacer

visible

In-flight entertainment system





17 17

Analog Resistive (IV)

x

y

2

1

R

Rx

4

3

R

Ry

‚Calculation„ of touch impact position

Multi touch ???

http://upload.wikimedia.org/wikipedia/de/8/81/Touchscreen.png





18 18

Analog Resistive (V)

• Size range: 2” to ~26”

• Major applications:

- Mobile devices (replaced in smartphones by projected capacitive)

- Point of sale (POS) terminals

• 2006 market share

- 90% by volume

- 75% by revenue

• Selected suppliers:

- Elo TouchSystems, Fujitsu, Gunze, Touch International…

- 50+ suppliers worldwide





19 19

Resistive Touch Screen Controller





20 20

Resistive Touch Screen Board





21 21

Resistive Touch Screen Protocol

Touch electronics use a communications protocol

- Embedded systems e.g. I2C, SPI, UART

- PC-based systems USB, RS232





23 23

Capacitive Overview

(no multi-touch)

Only small changes of capacity

are forced by finger etc.

sophisticated touch controller

and algorithms needed





24 24

Projected Capacitive (I)

Principle: Electrical field changes due to influence of dielectric parameter

Push (like whole touch awareness) by APPLE‟s IPHONE





25 25

Projected Capacitive (II)

Screen

• A specially structured multi-layer

ITO-film is fully laminated to a

glass substrate.

• By the specially structured electrodes

an electric field will be „projected“

through the glass substrate.

• This electric field changes due to the

influence of a touch element (finger).

The dielectric parameter will change

and the controller can calculate the

position of this change.

• The touch finger does not need to

be conductive !





26 26

Projected Capacitive (III)





27 27

Projected Capacitive (IV)

Data acquisition path





28 28

Projected Capacitive (V)

IPHONE Hardware





29 29

Projected Capacitive (VI)

IPHONE integration





30 30

Projected Capacitive (VII)

IPHONE HMI Examples





31

Projected Capacitive Touch Integration

Source: Display Search 2012

“one glass”





32 32

P-Cap Touch Signal Processing

- Control sensor electrodes to generate raw data

Noise avoidance via multiple techniques: Frequency Shifting, CDM, etc…

- Process data to convert to image data

- Derive and report data about finger touches (position, width, gestures)





33 33

P-Cap Touch Screen Method

The basic construction of a projected capacitive sensor typically uses two

dielectrically separated layers of glass patterned with ITO that are configured

in rows and columns positioned perpendicularly to create a matrix. Projected

capacitive functionality is achieved by scanning along each axis, identifying

high capacitance lines, then determining a position by the intersection of

those high capacitance lines. This scanning system and the sensor pattern

allow potential decoding of multiple simultaneous touch points known as

„„multi-touch‟‟ capable.

Two capacitance

measurement methods:

- Capacitive Sensing (CSM)

- Charge Time Measure

Units (CTMU).





34 34

P-Cap Touch Screen Board





35 35

P-Cap Touch Screen HW & SW





42 42

Surface Acoustic Wave (SAW)





43 43

Integrated Touch

In-cell light sensors

capture position like

a flat camera

Multi touch !





44 44

• Integration of an array of TFT optical sensors into the LCD‟s backplane

• Like a “camera without a lens”

• Works with finger, stylus, light-pen or laser pointer

• Works as a scanner (e.g., for business cards)

• TMD was in 2003, SHARP announced MP for 2008

Image on 2.6” VGA (300 ppi)

Integrated Touch





45 45

Camera Based





46 46

Radar Touch

• Excellent for large sized screens

• Gesture OK

• Lacks of multi touch by

geometric blocking





47 47

Dual & Multi Touch





48

Mobile Infrared Touch

Source: Walker, public and private





49 49

Comparison

Technology Multi-

touch Resolution

Form factor

(bezel) Cost

Resistive

No

100+ dpi,

any object

Up to 5mm on all

sides Low

Surface

Capacitive No

10 dpi , only finger; no pen input

Minimal Medium

Projected

Capacitive Yes

10 dpi - only

works with a

human finger

Minimal High

- All touch screens reduce clarity and enhance reflectivity of the display

- All touch screens rise power consumption:

LCD – Backlight or emissive luminance must be enhanced





50 50

• Introduction


Overview


• Summary





51

Touch Technology Comparison

Source: M. Jones





53

Touch Technology Comparison for Applications

Source: M. Jones





54 54

Touch Screens & Ambient Light





55 55

Touch Screens & System • Total cost of ownership: Consider initial purchase price plus long-term

costs including operation and maintenance

• Accepted input devices

Is it important that the application work with a finger, a gloved finger, a

metal stylus, a nonconductive stylus, a credit card, and/or a long fingernail?

• Durability: How harsh is the intended environment?

Will the system be used in the public sector (vandal considerations)?

• Image quality of the underlying display: Are clarity, brightness and

readability of the display important to the application?

• Sealability and chemical resistance: Is the screen/device likely to be

subjected to spills and/or cleaning with harsh chemicals?

• Reliability: What is the impact of any downtime for repair?





57 57

• Introduction


Overview


• Summary





58 58

Summary

• Touch screens have many advantages like HMI

• Mature technologies available

• Integration needs some expertise incl. ambient light

• Not every touch technology is suitable for dedicated applications

Touch has many benefits

but need some system considerations





59 59

Summary





60 60

Touch Screen Companies

Name Internet Technology

A D Metro www.admetro.com C, R

Bergquist www.bergquistcompany.com R

Chi Lin Technology/

NextWindow

www.chilintech.com.tw

www.nextwindow.com

R, Opt

DigiTech Systems www.digitechsys.co.kr C, R

EGalax www.egalax.com.tw Cont

Elo TouchSystems www.elotouch.com APR, C, IR,

PC, R, SAW

Fujitsu www.fcai.com R

Gunze www.gunzeusa.com R

Hampshire www.hampshirecompany.com Cont





61 61

Touch Screen Companies

Name Internet Technology

Horizon Technology www.horizontechnology.com SAW

Immersion www.immersion.com TF

IRTouch Systems www.irtouch.com IR

Northpoint Techn. www.northpointech.com C, R

Smart Technologies www.smarttech.com Opt

SMK Electronics www.smkusa.com IR, R, TF

Touch International www.touchinternational.com C, IR, PC, R

Touch KO/ White

Electronic Designs

www.touchko.com

www.wedc.com

PC, R

Wacom www.wacom.com EMR

Zytronic www.zytronic.co.uk PC





62 62

What Touch Screen Technology Is It ? (I)

• If it responds, it‟s either infrared or optical

- Resistive needs pressure

- Surface & projected capacitive need a finger

- Surface acoustic wave needs a sound-absorbing contact

- APR/DST (bending wave) needs a firmer touch

• Block the corners of the screen with something opaque

- If it still responds to a touch away from the corners, it‟s infrared

(IR transceivers are distributed all around the periphery)

- If it stops responding, it‟s optical

(imaging cameras are located in the corners)

Brush the screen very lightly with Kleenex





63 63

What Touch Screen Technology Is It ? (II)

• If it didn‟t respond, poke it with a toothpick

- If it responds, it‟s resistive or APR/DST (bending wave)

- Surface & projected capacitive need a finger


- Check to see if the surface moves ever so slightly when you

poke it with the toothpick (watch a reflection of a light source

on the surface of the screen and try several locations)

- If the surface moves, it‟s resistive (the surface is PET)

- If the surface doesn‟t move, it‟s APR/DST (bending wave)

the surface is glass






64 64

What Touch Screen Technology Is It ? (III)

If it didn‟t respond, touch it with a pencil eraser

- If it responds, it‟s surface acoustic wave


- If it doesn‟t respond, it‟s either surface or projected capacitive

- Surface capacitive and projected-capacitive need a finger

- Check for faintly visible straight or jagged lines in a repeating

pattern in the darkest areas of the screen (the lines are most

visible when the screen is powered off and you‟re looking at

the surface using reflected light)

- If you see lines, it‟s projected capacitive

(you‟re seeing the transparent conductors on the sensor)

- If you don‟t see any lines, it‟s surface capacitive


Documents

Karlheinz Blankenbacheitidaten.fh-pforzheim.de/.../displays/ed_touch_short.pdf · 2013-01-13 · D I S P L A Y L A B PFORZHEIM UNIVERSITY Blankenbach / Pforzheim Univ. / / Bachelor