Resistive, capacitive, infrared, and SAW are the main types of touch screen technologies. Resistive touch screens use two electrically conductive layers separated by a gap, such that a touch causes a change in electrical current. Capacitive touch screens use a transparent conductor coated glass and detect changes in capacitance from a human touch. Infrared touch screens use an array of infrared beams to detect touch disruptions. SAW touch screens use ultrasonic waves absorbed by a touch. Each technology has advantages like cost, accuracy, and durability, as well as disadvantages such as sensitivity to liquids or lack of multi-touch support.

1. PRESENTATION ON TOUCH TECHNOLOGY IN MOBILES

2. Introduction
A touch screen is an electronic visual
display that can detect the presence
and location of a touch within the
display area. Touch screens can sense
Finger and other passive objects, such
as a stylus. However, if the object
sensed is active, as with a light pen.

3. History & Development
• In 1971 Dr. Sam Hurst, founder of Elographics developed the
first touch opaque sensor “Elograph” at the University of
Kentucky.
• In 1974 He developed the first real touch screen.
• In 1977, Elographics developed the five-wire resistive
technology then with the backing of Siemens Corporation,
developed a curved glass sensor called the touch screen.

4. Dr. Samuel Hurst
The father of the touch screen technology
is Dr. Samuel Hurst. In 1971, while he was
working as an instructor at the University of
Kentucky Research Foundation, he had to
read a great volume of information during
the graduation exams. In an effort to save
some time he invented the first touch sensor
that he called “Еlo graph”(electronic
graphics), which allowed him to enter data
faster.

5. First Touch Phone
Apple was the first with a touch
screen phone in 1983. Jason
Ford of Elo Touch Systems, the
company whose founder
invented touch screen
technology, for providing the
touch technology. In 1971, the
first "touch sensor" was
developed by Doctor Sam
Hurst.

6. First Touch Mobile
The Nokia 7710 is a first touch
screen mobile phone model
produced by Nokia. The 7710 is
based on the Nokia 7700 which
was never released. It is Nokia's
first, and so far only smart phone
to run the Series 90 GUI a top
the Symbian OS.

7. Types of Touch Technologies
There are mainly 4 types of touch Technologies:-
1.Resistive
2. Surface acoustic wave
3. Capacitive
4. Infrared

8. Resistive
A resistive touch screen panel is composed
of several layers, the most important of
which are two thin, metallic, electrically
conductive layers separated by a narrow
gap. When an object, such as a finger,
presses down on a point on the panel's outer
surface the two metallic layers become
connected at that point. This causes a
change in the electrical current, which is
registered as a touch event and sent to
the controller for processing. It is used
in Grocery Stores, Hotels, Restaurants and
Retail Stores.

9. Advantages & Disadvantages of Resistive
• Advantages
– Cost-effective solution
– Activated by any stylus
– Very accurate
– Low power requirements
– Liquids won't affect touch screen performance
• Disadvantages
– Polyester surface can be damaged
– Lower endurance (35 million touches)

10. Surface Acoustic Wave (SAW)
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. SAW touch screen technology
is suggested for use in ATMs, Amusement Parks, Gaming
Environments, Industrial Control Rooms etc.

11. Advantages & Disadvantages of SAW
• Advantages
– Durable glass construction
– High optical clarity
– Activated by a finger, gloved hand, or soft tip stylus
• Disadvantages
– Moving liquids or condensation can cause false touches
– Solid contaminants create non-touch areas until removed
– Doesn't support drag or draw effectively

12. Capacitive
A capacitive touch screen panel
consists of an insulator such
as glass, coated with a
transparent conductor such
as indium tin oxide (ITO). As the
human body is also a conductor,
touching the surface of the screen
results in a distortion of the
body's electrostatic field,
measurable as a change
in capacitance.

13. Advantages & Disadvantages of Capacitive
• Advantages
– Scratch resistant, durable surface
– High endurance (225 million touches)
– Very accurate
– Good optical clarity
– Liquids won't affect touch screen performance
• Disadvantages
– Does not work with gloved fingers or stylus

14. Infrared
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. Infra-red bezels have
proven to be a very reliable
technology for use in
ATMs,Medical Instrumentation
and Transportation Tracking
applications.

15. Advantages & Disadvantages of Infrared Touch
Screen
• Advantages
-Highest quality of underlying image
-Very high transmittance
-Excellent anti-glare, with use of chemically etched glass
-Can be activated with almost any device
-Higher accuracy than other technologies
-Very high durability and reliability
• Disadvantages
- Surface obstructions can cause a false touch
– It is very sensitive and can be activated by stray touches.
– Low resolution
– Parallax problems

16. Touch Screen Technology Comparison Chart
Resistive Infrared SAW Capacitive
Touch
Resolution
High High Average High
Clarity Average Good Good Good
Operation Finger or Stylus Finger or Stylus Finger or Soft-
tipped Stylus
Finger only
Durability Can be
Damaged by
Sharp Objects
Highly Durable Susceptible to
Dirt and
Moisture
Highly durable

17. Advantages & Disadvantages of all Touch
Technology
Touch screens have several advantages over other pointing devices:
• A touch screen is easy to use (as the user simply touches what he or
she sees on the display).
• Save space as no buttons are required.
• Touching a visual display of choices requires little thinking and is a
form of direct manipulation that is easy to learn.
• Touch screens are the fastest pointing devices.
• Touch screens have easier hand eye coordination than buttons.
• Touch screens are durable in public access and in high volume usage.

18. Disadvantages
• Screen has to be really big not to miss things when pressing them with
your finger:
• Big screen leads to low battery life.
• Touch screen means screen can’t be read too well in direct sunlight
as it applies an additional not 100% transparent.
• Screens get very dirty.
• These devices require massive computing power which leads to slow
devices.

19. CLOSING THOUGHTS
Though the touch screen
technology contains some
limitations it’s very user
friendly, fast, accurate, easy
for the novices & fun to
operate. It has been widely
accepted. And now by just
modifying a little it can
replace the mouse and key
board completely in near
future.