Touch Screen Sensors

Thomas Shupe

ECE 5320 Mechatronics

Assignment #1

Outline

• References• To explore further• What are touch screen sensors• Different types touch screen sensors• Working principles• Major applications• Cost• Where to buy

References

• http://en.wikipedia.org/wiki/Touchscreen

• http://www.touchscreens.com/intro-anatomy.html

• Research Note on Touch Screen Sensors by Andrew Nathanson

• http://www.wisegeek.com/what-are-touch-screen-monitors.htm

To Explore Further

• http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci214510,00.html

• http://www.howstuffworks.com/question716.htm

• Multi-Touch Interaction Research

by Jeff han http://cs.nyu.edu/~jhan/ftirtouch/

What are Touch Screen Sensors?

• “A Touchscreen is a display which can detect the location of touches within the display area. This allows the display to be used as an input device, removing the keyboard and/or the mouse as the primary input device for interacting with the display's content.”

http://en.wikipedia.org/wiki/Touchscreen

Types of Touch Screen Sensors

• External add on touch screens

• Integrated Touch Screen Monitors

External Add On Touch Screen Sensor

• Can be added to your home computer

• Brings touch screen technology to the common user

http://www.touchscreens.com/intro-anatomy.html

Integrated Touch Screens

• The sensor system is already integrated into the screen or monitor

http://techon.nikkeibp.co.jp/english/NEWS_EN/20071025/141314/thumb_430_iiD.jpg

Working Principles

http://www.touchscreens.com/intro-anatomy.html

•A clear touch sensor is placed over the viewable video screen

Working Principles

• A controller (2) takes information from the touch screen (1)

• The info is turned into information the computer can understand

• A software driver is needed to allow the touch screen and computer to work together (3)

http://www.touchscreens.com/intro-anatomy.html

Working PrinciplesMultiple Types of Touch Sensors

• Resistive

• Surface Acoustic Wave

• Capacitive

• Infrared

• Strain Gage

Resistive

• Composed of several layer including two metallic layers separated from each other

• When metallic layers are connected (touched) they act as like 2 voltage dividers

• Change in electric current is sent to controller and the location is determined

http://www.made-in-china.com/image/2f0j00bMTQkrgBRYpuM/Metal-Oxide-Film-Fixed-Resistor.jpg

Surface Acoustic Wave

•Uses Ultrasonic waves across the surface

•When the screen is touched part of the wave is absorbed

•This allows the controller to determine the position of the touch

http://magicseaweed.com

Capacitive

• Coated with a current conducting material

• Sensor has a precisely controlled field of stored electrons in horizontal and vertical directions

• Humans also exhibit capacititance• A controller detects when there is a

disturbance in the electric field (touch)• The controller then determines the location

www.inelectronicsltd.co.uk

Infrared

• An array of infrared sensors are placed horizontally and vertically

• The sensors send out pulses of light

• The sensors detect the interruption of the light

• The location is then determined by the controller

Strain Gage

http://etestinc.com/db4/00336/etestinc.com/_uimages/strainguage.bmp

•Screen is mounted on four springs one at each corner

•Deflection of screen when touched is measured by all four strain gages

•Calculations are made based on each of the four deflections to determine the location of the touch

Typical Applications

Credit Card Scanners

Typical Applications

Consumer Electronics• Phones

• PDA’s

• Digital Cameras

• GPS

• etc

www.trafficdominatetricks.com/jv/prizes.htm techwoo.com/hp-ipaq-112-classic-pda-phone/

http://migs.wordpress.com/2007/06/28/new-touch-screen-phones/

Typical Applications

ATM

http://www.acceptvisaandmastercard.com/assets/images/atm1.jpg

Interactive Kiosks and learningstations

http://www.mce-sign.com/images/produits_multimedia/kaori.gif

Etc. Etc. Etc.

Cost

• Overlay screen $169 - $299

• Integrated Touch Screen Monitor– 12” LCD $609– 17” Monitor $539– 42” LCD $4872

http://2make-money.biz/images/money344.jpg

Where To Buy

• www.touchscreens.com

• http://www.ezscreen.com/

• http://www.abilityhub.com/mouse/touchscreen.htm