touch screen technology their types and working technology. by - DILIP KUMAR NIT CALICUT

1. SEMINAR
ON
TOUCH SCREENS
Presented by:DILIP KUMAR
M110376CA
NIT CALICUT

2. POINTS TO DISCUSS
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INTRODUCTION TO THE TECHNOLOGY
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HISTORY AND DEVELOPMENT
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CONSTRUCTION OF TOUCH SCREEN
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TOCH TECHNOLOGIES
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APPLICATIONS
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CLOSING THOUGHTS
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REFERENCES

3. INTRODUCTION
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A touch screen is computer display screen that is sensitive to
human touch.
It is the most user friendly input device used to interface with a
PC.
The display screen has a sensitive glass overlay placed on it
and we could give the desired input by touching it.
Touch screens can sense finger and other passive objects,
such as a stylus.
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A touch screen kit includes a touch screen panel, a controller
and a software driver.
A touch screen accepts direct onscreen inputs.

4. HISTORY AND DEVELOPMENT
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In 1971, the first “touch sensor” was developed by Dr. Sam
Hurst (founder of elographics) while he was an instructor at the
university of Kentucky.
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In 1974 he developed the first real touch screen.
The new transparent technology, Accu Touch , was later
developed by the founders of Elographics, Dr. Hurst and Bill
Colwell.
Apple was the first with a touch screen phone in 1983.
The nokia 7710 is a first touch screen mobile phone model
produced by Nokia.

6. CONSTRUCTION OF TOUCH
SCREEN
A basic touch screen has three main components -:
* A touch sensor
* A controller
* Software driver
The touch screen is an input device so it needs to be combined
with a display and a PC or other device to make a complete
touch input system.

7. TOUCH SENSOR
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A touch sensor is a clear glass panel with a touch responsive
surface.
The touch sensor/panel is palced over a display screen so that
the responsive area of the panel covers the viewable area of
the video screen.
The sensor generally has an electronic current or signal going
through it and touching the screen causes a voltage or signal
change.
This voltage change is used to determine the location of the
touch screen.

8. CONTROLLER
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The controller is a small PC card that connects between the
touch sensor and the PC.
It takes information from the touch sensor and translates it into
information that PC can understand.
The controller is usually installed inside the monitor for
integrated monitor or it is housed in a plastic case for the
external touch add-ons/overlays.
Integrated touch monitor will have an extra cable connection on
the back for the touch screen.Controllers are available that can
connect to a serial/COM port(PC) or to a USB port.

10. SOFTWARE DRIVER
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The driver is a software update for the PC system that allows
the touch screen and computer to work together.
It tells the computer's operating system how to interpret the
touch event information that is sent from the controller.
Most touch screen drivers today are mouse-emulation type
driver. This makes touching the screen the same as clicking
mouse at the same location on the screen.
This allows the touch screen to work with existing software and
allows new applications to be developed without the need for
the touch screen specific programming.

11. TOUCH TECHNOLOGIES
There are mainly 4 types of touch screen technologies -:
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Resistive
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Capacitive
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Surface acoustic wave
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Infrared

12. RESISTIVE TECHNOLOGY
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Respond to the pressure of a finger or stylus .
When pressure is applied to the screen, the controller registers
the touch event.
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Polyster film
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Top resistive layer
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Conductive transparent metal coating
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Bottom resistive layer
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Insulating dots
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Glass substrate.

14. ADVANTAGES & DISADVATGES
ADVANTAGES -:
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Cost effective solution.
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Activated by any stylus.
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Very accurate
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Low power requirement.
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Liquids won't affect touch screen performance.
DISADVATAGES -:
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Polyster surface can be damaged.
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Poor durability compared to other technologies.

15. CAPACITIVE TECHNOLOGY
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A capacitive touch screen panel is consists of an insulator such as
glass, coated with a transparent conductor like indium tin oxide
(ITO).
In this a layer that stores electrical charge is placed on the glass
panel.
When a user touches , some of the charge is transferred to the
user, so the charge on the capacitive layer decreases.
This decrease is measured in electrodes located at each corner of
monitor.
The computer then calculates the coordinates, from the relative
differences in charge at each corner. Then the controller measures
the ratio of the current flow from the corners and calculate touch
location.

17. ADVANTAGES -:
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More durable than resistive.
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Higher transmittance than resistive.
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High clarity.
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Scratch resistant .
DISADVATAGES -:
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Does not work with gloved finger or stylus.
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Accepts input from finger only.
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Accuracy is dependent on capacitance of person.
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Can be affected by electricity.

18. SURFACE WAVE TECHNOLOGY
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Surface acoustic wave (SAW) technology uses ultrasonic
waves that pass over the touch screen panel.
When the panel is touched, a portion of the wave is absorbed.
This change in the ultrasonic waves registers the position of the
touch event and sends this information to the controller for
processing.
This technology is used in ATMs, amusement parks, gaming
environments, industrial control room etc.

20. ADVANTAGES -:
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Very high transmittance.
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Very high durability.
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Fast touch response.
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Finger or gloved hand operation.
DISADVANTAGES -:
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Must be touched by finger, gloved hand, or soft stylus.
Something hard like pen won't work.
Can be affected by large amounts of grease, water, or dirt on
the screen.
Surface obstructions can cause a false touch.

21. INFRARED TECHNOLOGY
An infrared touch screen uses an array of X-Y infrared LED and
photo detector pairs around the edges of the screen to detect a
disruption in the pattern of LED beams.

23. ADVANTAGES -:
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Mostly used in manufacturing and medical applications.
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Operated using a stylus or a gloved finger.
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More wear resistant.
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Very high durability and reliability.
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Can be activated with almost any device.
DISADVANTAGES -:
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Lower resolution than other technologies.
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Surafce obstructions can cause a false touch.
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It is very sensitive and can be activated by stray touches.

24. APPLICATIONS
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Public information displays - tourism displays, trade show
displays.
Customer self services- stores,restaurents, transpotation hubs
ATM, airline e-ticket terminal.
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Computerized gaming
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Industrial process control.
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Home automation systems.
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Casino and other gaming systems.
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Computer access for the physically disabled people.
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Financial and scientific applications and more.

25. CLOSING THOUGHT
Though the touch screen technology contains some limitations
it's very user friendly , fast, accurate and fun to operate. It has
been widely accepted and now by just modifying a little it can
replace the mouse and keyboard completely in near future.

26. REFERENCES
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Bent STUMPE (6 February 1978), Experiments to find a
manufacturing process for an x-y touch screen, CERN,
retrieved 2010-05-25
"TapSense: Enhancing Finger Interaction on Touch Surfaces".
Retrieved 28 January 2012.
The first capacitative touch screens at CERN, CERN Courrier,
31 March 2010, retrieved 2010-05-25
http://en.wikipedia.org/wiki/Touchscreen