1. Touch Screen Sensors

2. Outline
What are touch screen sensors
Different types touch screen sensors
Working principles
Major applications
 References

3. What are Touch Screen Sensors?
“A Touchscreen is a display which can detect the
location of touches within the display area. This
allows the display to be used as an input device,
removing the keyboard and/or the mouse as the
primary input device for interacting with the
display's content.”

4. Types of Touch Screen Sensors
External add on touch screens
Integrated Touch Screen Monitors

5. External Add On Touch Screen Sensor
Can be added to your home computer
Brings touch screen technology to the common user

6. Integrated Touch Screens
The sensor system is already integrated into the
screen or monitor

7. Working Principles
•A clear touch sensor is placed over
the viewable video screen

8. Working Principles
A controller (2) takes information from the touch
screen (1)
The info is turned into information the computer
can understand
• A software
driver is needed
to allow the touch
screen and
computer to work
together (3)

9. Working Principles
Multiple Types of Touch Sensors
Resistive
Surface Acoustic Wave
Capacitive
Infrared
Strain Gage

10. Resistive
Composed of several layer including two metallic
layers separated from each other
When metallic layers are connected (touched) they
act as like 2 voltage dividers
Change in electric current is sent to controller and
the location is determined

11. 4-wire resistive touchscreen

12. Surface Acoustic Wave
•Uses Ultrasonic waves across the surface
•When the screen is touched part of the
wave is absorbed
•This allows the controller to determine the
position of the touch

13. Capacitive
Coated with a current
conducting material
Sensor has a precisely controlled field of stored
electrons in horizontal and vertical directions
Humans also exhibit capacititance
A controller detects when there is a disturbance in
the electric field (touch)
The controller then determines the location

14. Surface-capacitive touchscreen
Structure
Surface capacitive technology consists of a
uniform conductive coating on a glass panel.
Electrodes around the panel’s edge evenly
distribute a low voltage across the
conductive layer, creating a uniform electric
field.

15. Projected-capacitive touchscreen
During a touch, capacitance forms between the
finger and the sensor grid.The embedded serial
controller in the touchscreen calculates touch
location coordinates and transmits them to the
computer for processing.

16. Surface-capacitive touchscreen
Working principle
A human body is an electric conductor, so when you touch the
screen with a finger, a slight amount of current is drawn, creating a
voltage.s Theoretically, the amount of current that drifts through
the four electrodes should be proportional to the distance from the
touch point to the four corners. The controller precisely calculates
the proportion of the current passed through the four electrodes
and figures out the X/Y coordinate of a touch point.

17. Infrared
An array of infrared sensors are placed horizontally
and vertically
The sensors send out pulses of light
The sensors detect the interruption of the light
The location is then determined by the controller

18. Strain Gage
http://etestinc.com/db4/00336/etestinc.com/_uimages/str
ainguage.bmp
•Screen is mounted on
four springs one at each corner
•Deflection of screen when touched is
measured by all four strain gages
•Calculations are made based on each
of the four deflections to determine the
location of the touch

19. Typical Applications
Consumer Electronics
Phones
Tab
Digital Cameras
GPS
etc
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20. Typical Applications
ATM
Interactive Kiosks
and learning
stations
Etc. Etc. Etc.

21. THANKING
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