Central Institute of Technology,
Touch Screen Technology
Roll No: Gau-C-12/48
Roll No: Gau-C-12/52
A touch screen is an
electronic visual display
that can detect the
presence and location of
a touch within the
screens can sense Finger
objects, such as a stylus.
However, if the objects
sensed is active, as with a
History and Development
In 1971 Dr. Samuel Hurst, founder of Elographics
developed the first touch 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 a curved glass sensor called the Touch
The new transparent technology, AccuTouch, was later
developed by the founder of Elographics, Dr. Hurst
and Bill Colwell.
First Touch Phone:
Apple was the first with a
touch screen phone in 1983.
First Touch Mobile:
The Nokia 7710 is the first
phone model produced by
Then they used it for the
Nokia Symbian OSs.
Construction Of Touch Screen
A basic touch screen has three main
A. A touch sensor
B. A controller
C. A software driver
A touch sensor is a clear glass
panel with a touch responsive
surface which is placed over a
display screen so that the
responsive area of the panel
covers the viewable area of the
The sensor generally has an
electrical 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 to the
The controller is a
small PC card
touch sensor and
the PC. It takes
the touch sensor
Supply voltage: 5volt
Maximum current: 20mA(Pick)
The driver is a software that allows the touch screen
and computer to work together. It tells the operating
system how to interpret the touch event information
that is sent from the controller
Most touch screen drivers today are a mouseemulation type driver. This makes touching the screen
the same as clicking your mouse at the same location
on the screen.
Types of Touch Technologies
There are mainly 4 types of touch technologies:
Surface acoustic wave(SAW)
A resistive touch screen panel
is composed of several layers,
the most important of which
electrically conductive layers
separated by a narrow gap.
When an object, such as a
finger, presses down on a
point, causes a change in the
electrical current, which is
registered as a touch event
and sent to the controller for
Advantages And Disadvantages of
Activated by any stylus
Low power requirements
Liquids won’t affect touch screen performance
Polyester surface can be damaged
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. The change in the
ultrasonic waves registers the
position of the touch event and
sends this information to the
controller for processing.
technology is suggested for use
in ATMs, Amusement Parks,
Industrial Control Rooms etc.
Advantages and Disadvantages of
-Durable glass construction
-High optical clarity
-Activated by a finger, gloved hand, or soft tip stylus
-Moving liquids or condensation can cause false touch
-Solid contaminants create non-touches
-Doesn’t support drag or draw effectively
A capacitive touch screen
panel consist 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
measurable as a change in
Advantages and Disadvantages Of
-Scratch resistance, Durable surface
-Good optical clarity
-Liquid won’t affect touch screen performance
-Does not work with gloved fingers or stylus
screen uses an array of
X-Y infrared LED and
photo detector pairs
around the edges of the
pattern of LED beams.
Infra-red bezels have
proven to be a very
reliable technology for
use in ATMs, Medical
Advantages and Disadvantages of
Infrared Touch Screen
-Highest quality of underlying image
-Very high transmittance
-Can be activated with almost any device
-Higher accuracy than other technologies
-Very high durability and reliability
-It is very sensitive & can be activated by stray touches
Apple was the first company
which introduce the touch
phone and after that Nokia
come into existence with their
Nokia 7710. Now a days Nokia,
technology. Some of the local
companies are also taking part
technology but these are not
effective in the environment.
Advantages of all Touch Technology
Touch screen have several advantages over other
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 have easier hand eye coordination than
Touch screens are durable in public access and high volume
Disadvantages of all Touch
Screen has to be really big not to miss things when
pressing them with finger. So the big screen leads to
low battery life.
Touch screen means can’t be read too well in direct
sunlight as it applies an additional not 100%
Touch screen devices usually has no additional keys
and this means when an application crashes, without
crashing the OS , you can’t get the main menu as the
whole screen becomes unresponsive.
Screens get very dirty.