The document explains touch screen technology as an input device that allows users to interact by touching the display. It details various types of touch screen systems, including resistive, capacitive, and surface acoustic wave, each having distinct mechanisms for detecting touch. The conclusion notes that despite some limitations, touch screens are user-friendly and are increasingly replacing traditional input methods.

1. TOUCH SCREEN TECHNOLOGY
-B.Sucharitha
(07H51A1208)

2. INTRODUCTION
 A touch screen is an input device
that allows users to operate a
device by simply touching the
display screen.
 The display screen has a
sensitive glass overlay placed on
it and we can give the desired
input by touching on it.
 The term generally refers to
touch or contact to the display
of the device by a finger or
hand.

3. HOW DOES A TOUCH SCREEN
WORK…???
 There are three basic systems that are
used to recognize a person's touch:
• Resistive
• Capacitive system
• Surface Wave

4. (i)RESISTIVE
 A touch screen sensor is a clear glass
panel surface with a touch responsive
surface which is placed over a display
screen.
 The sensor generally has an electric
current or signal going through it and
touching the screen causes a voltage or
a signal change.

6. (ii) CAPACITIVE SYSTEM
 This is a small device card that
connects the sensor and the main
hardware device.
 It takes information from the sensor
and translates it into information that
device can understand.

7. (iii) SURFACE WAVE
 It is the software that allows the touch
screen and the device to work together.
 It tells the main hardware device how to
interpret the touch event information
that is sent from the controller.
 Most of the devices are a mouse-
emulation type driver.

8. TOUCH SCREEN TECHNOLOGIES
 Resistive touch screen
 Surface acoustic wave touch screen
 Capacitive touch screen
 Infrared touch screen
 Acoustic pulse technology
 3M Dispersive Signal Technology (DST)

9. RESISTIVE TOUCH SCREEN
 A resistive touch screen panel
is composed of several layers,
the most important of which
are two thin, 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.

10. SURFACE ACOUSTIC WAVE TOUCH
SCREEN
 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.

11. CAPACITIVE TOUCH SCREEN
 A capacitive touch screen
panel is one which 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 screen's electrostatic
field, measurable as a
change in capacitance.

12. INFRARED TOUCH SCREEN
 An infrared touch screen uses
a ray of X-Y infrared LED and
photodetector pairs around
the edges of the screen to
detect a disruption in the
pattern of LED beams.
 These LED beams cross each
other in vertical and
horizontal patterns. This helps
the sensors pick up the exact
location of the touch.
 A major benefit of such a
system is that it can detect
essentially any input including
a finger, gloved finger, stylus
or pen.

13. ACOUSTIC PULSE RECOGNITION
 This system uses piezoelectric transducers located at
various positions around the screen to turn the mechanical
energy of a touch (vibration) into an electronic signal.
 The screen hardware then uses an algorithm to determine
the location of the touch based on the transducer signals.
 This touchscreen technology gives good durability and
optical clarity.
 It is usually able to function with scratches and dust on
the screen with good accuracy.
 The technology is also well suited to displays that are
physically larger.

15. 3M Dispersive Signal Technology (DST)
 Traditional touch technologies detect touch locations by
interrupting acoustic waves, optical fields or infrared light
above the surface of the touch screen.
 Dispersive Signal Technology (DST), however, precisely
calculates touch locations within the glass substrate by
analyzing the bending waves created by the user's touch.
 This allows for fast, accurate and reliable touch performance
that is unaffected by contaminants, scratches or static
objects on the screen, as well as enabling stylus support and
multi-user capability.
 3M Dispersive Signal Technology (DST) is poised to become
the touch technology standard for large-format interactive
displays.

16. USAGE
 Finger stress:
With stressing the finger on the desired
area of the touch screen, the input is taken by
the sensors of the screen.
 Finger nail as stylus:
With the help of touching the screen with
the finger mail which acts as the stylus, input
can be taken by the sensors.

17. MULTI-TOUCH TECHNOLOGY
 On touchscreen displays, multi-touch refers
to the ability to simultaneously register three
or more distinct positions of input touches.

18. ADVANTAGES
 User friendly
 Fast response
 Error free input
 User finger, finger nail, gloved hand,
stylus or any soft tip pointer to operate
 Make computing easy, powerful and fun

19. DISADVANTAGES
 1)Finger stress:
Stress on human fingers when used
for more than a few minutes
at a time. (for example, ATMs).
 2)Fingerprints:
Touchscreens can suffer from the
problem of fingerprints on the display.

20. CONCLUSION
Though the touch screen technology
contains some limitations with it, it is
fast, accurate, user friendly and fun to
operate .It is being widely accepted.
With some modifications, it can
completely replace mouse and keyboard
completely in the near future.