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Touch Screen Technology
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.
HOW DOES A TOUCH SCREEN
WORK…???
- There are three basic systems that are
used to recognize a person's touch
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
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
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 mouseemulation type driver.
TOUCH SCREEN TECHNOLOGIES
- Surface acoustic wave touch screen
- Acoustic pulse technology
- 3M Dispersive Signal Technology (DST)
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.
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.
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.
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.
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.
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.
USAGE
- With stressing the finger on the desired
area of the touch screen, the input is taken by
the sensors of the screen.
- With the help of touching the screen with
the finger mail which acts as the stylus, input
can be taken by the sensors.
MULTI-TOUCH TECHNOLOGY
- On touchscreen displays, multi-touch refers
to the ability to simultaneously register three
or more distinct positions of input touches.
ADVANTAGES
- User finger, finger nail, gloved hand,
stylus or any soft tip pointer to operate
- Make computing easy, powerful and fun
DISADVANTAGES
- Stress on human fingers when used
for more than a few minutes
at a time. (for example, ATMs).
- Touchscreens can suffer from the
problem of fingerprints on the display.
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.
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