Description of various touch screen type

1. Arun Rajput

2. Talk Flow
Introduction
History
Working
Different touch Screen Technology
Application
Conclusion

3. Introduction
A touch screen is a computer display screen that is
sensitive to human touch, allowing a user to interact with the
computer by touching pictures or words on the screen.
A touch screen is an input device that allows users to operate a PC by
simply touching the display screen which has a sensitive glass overlay
placed on it .
A touch screen accepts direct onscreen
inputs.

4. History
In 1971, the first "touch sensor" was developed by Doctor Sam Hurst
(founder of Elographics) while he was an instructor at the University of
Kentucky
The University of Kentucky Research Foundation named it as “Elograph”.
In 1974, the first true touch
screen incorporating a transparent
surface came.
The "Elograph" was not transparent like modern touch screens.
Figure : The first Touch Screen

5. Working of Touch Screen
A basic touch screen has three main components:
Touch Sensor Controller
Software
Driver

6. 1. Touch Sensor
A touch screen sensor is a clear glass panel
with a touch responsive surface which is
placed over a display screen.
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 screen. Fig.- Touch Sensor

7. 2. Controller
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.
Fig.- Controller
Controllers are available that can connect to
a Serial/COM port (PC) or to a USB port
(PC or Macintosh). Specialized controllers
are also available that work with DVD
players and other devices.

8. 3. Software Driver
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 mouse-emulation type drivers. This
makes touching the screen the same as clicking your mouse at the same
location on the screen.

9. Type of Touch Screen Technologies
Resistive Touch Technology
Capacitive Touch Technology
Infrared Touch Technology
Surface wave Touch Technology
Optical Touch Technology

10. 1. Resistive Touch Technology
Pressing the flexible top sheet creates
electrical contact with the coating on
the glass.
The touch screen controller gets the
alternating voltages between the
two layers and converts them into
the digital X and Y coordinates of
the activated area.
Fig.- Working

11. Advantages & Disadvantages
Poorer durability compared to
other technologies
Very short life, especially
considering cosmetic wear
Low power consumption
Can be activated with any device
Low cost solution

12. 2. Capacitive Touch Technology
1
• In the capacitive system, a layer that stores electrical
charge is placed on the glass panel.
2
• When a user touches, some of the charge is transferred to
the user, so the charge on the capacitive layer decreases.
3
• This decrease is measured in electrodes located at each
corner of the monitor.
4
• The computer then calculates the coordinates, from the
relative differences in charge at each corner.

13. 2. Capacitive Touch Technology
A finger touch draws current from each corner.
Then the controller measures the ratio of
the current flow from the corners and
calculates the touch location

14. Advantages & Disadvantages
Higher transmittance than
resistive
Accepts input from finger only.
Accuracy is dependent on capacitance
of person
More durable than resistive

15. 3. Surface Wave Touch Technology
1
• It has a transmitting and receiving transducers for both the X and Y axes
2
•The touchscreen controller sends a five-megahertz electrical signal to the transmitting
transducer, which converts the signal into ultrasonic waves within the glass.
3
•These waves are directed across the front surface of the touchscreen by an array of
reflectors.
4
•Reflectors on the opposite side gather and direct the waves to the receiving transducer,
which reconverts them into an electrical signal.
5
•When you touch the screen, you absorb a portion of the wave travelling across it.
6
•The receivers can detect a drop in amplitude and thus coordinate is calculated.

16. Advantages & Disadvantages
Very high transmittance
Very high durability
Requires “soft” input
device
Surface obstructions can
cause a false touch

17. 4. Infrared Touch Technology
1
• IR makes use of a “frame” around the perimeter of the
display. On two sides there are closely spaced IR LEDs and on
the opposing two sides there are matching photo transistors.
2
• The LEDs are turned on in sequence and the signal is read
from the matching transistor. If no signal is read, then that
indicates a blocked IR beam, meaning a touch.

18. Advantages & Disadvantages
Highest quality of
underlying image
Very high transmittance
Very high durability and
reliability
Lower resolution than
other technologies
Surface obstructions can
cause a false touch

19. 6. SHADOWSENSE -Latest Touch Technology
A typical configuration of a ShadowSense touchscreen
utilizes four (4) sensors on the top bar; one in each corner and two mid-span. For
illumination, 940 nm IR LEDs are deployed on both sides and the bottom of frame
A Shadow Sensor is a patented sensor that is
capable of detecting the angle of a ray of light
based on the shadow cast on the sensor.
The sensor itself consists of a couple of light
detecting pixels and a mechanical roof that
covers half of one of the pixels.
Construction :-

20. Application of Touch Screen
Public Information Displays
Assistive Technology
Retail and Restaurant Systems
Control and Automation Systems
Computer Based Training

21. Conclusion

22. Refrences
- Beyers, Tim (2008-02-13). "Innovation Series: Touchscreen Technology". The Motley
Fool. Retrieved 2009-03-16
- Technology Trends: 2nd Quarter 1986, Japanese Semiconductor Industry Service -
Volume II: Technology & Government
Frank BECK & Bent STUMPE (24 May 1973). "Two devices for operator interaction in
the central control of the new CERN accelerator" (PDF). CERN. Retrieved 2010-05-25

23. THANK-YOU