1. TOUCH SCREEN TECHNOLOGY

2. Satendra Kumar 1st sem Mechanical Eng
Presented By
Satendra Kumar
1st sem
Mechanical Eng

3. TALK FLOW INTRODUCTION HISTORY FUNCTIONS WORKING
DIFFRENT TOUCH SCREEN TECHNOLOGIES
APPLICATION
CONCLUSION

4. 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.

5. 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”.
The "Elograph" was not transparent like modern touch screens.
In 1974, the first true touch screen incorporating a transparent surface came.

6. FUNCTIONS OF TOUCH SCREEN
Pressure sensitive activation-by finger or stylus.
Emulates mouse functions-click, double click, & drag.
Touch screen & mouse can be used concurrently.
Durable & scratch resistant coated surface.
Compatible with Windows 95,98,NT,2000,XP,Macintosh,Linux.

7. HOW DOES A TOUCHSCREEN WORKS?
A basic touch screen has three main components:
touch sensor
controller
software driver

8. 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.

10. 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.

11. 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.

13. DIFFERENT TOUCH SCREEN TECHNOLOGIES
RESISTIVE
CAPACITIVE
SURFACE WAVE
INFRARED
DISPERSIVE SIGNAL TECHNOLOGY

14. RESISTIVE TOUCH SCREEN TECHNOLOGY
Polyester Film .
Top Resistive Layer.
Conductive Transparent Metal Coating.
Bottom Resistive Layer .
Insulating Dots .
Glass Substrate

16. Contd.
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.

17. Advantages of Resistive Technology
Can be activated with any device
Low cost solution
Low power consumption

18. Disadvantages of Resistive Technology
Poorer durability compared to other technologies
Very short life, especially considering cosmetic wear

19. CAPACITIVE TOUCH SCREEN TECHNOLOGY
In the capacitive system, a layer that stores electrical charge is placed on the glass panel.
When a user touches, some of the charge is transferred to the user, so the charge on the capacitive layer decreases.
This decrease is measured in electrodes located at each corner of the monitor.
The computer then calculates the coordinates, from the relative differences in charge at each corner.

20. Contd. 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

21. Capacitive Technology
ADVANTAGES
  More durable than resistive
Higher transmittance than resistive
DISADVANTAGES
    Accepts input from finger only.
                       
    Accuracy is dependent on capacitance of person

22. SURFACE WAVE TECHNOLOGY
It has a transmitting and receiving transducers for both the X and Y axes.
The touchscreen controller sends a five-megahertz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass.
These waves are directed across the front surface of the touchscreen by an array of reflectors.

24. Contd.
Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal.
When you touch the screen, you absorb a portion of the wave travelling across it.
The receivers can detect a drop in amplitude and thus coordinate is calculated.

25. ADVANTAGES
    Very high transmittance
   Very high durability  
DISADVANTAGES
  Requires “soft” input device
Surface obstructions can cause a false touch

26. INFRARED TOUCH SCREEN TECHNOLOGY
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.
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.

28. ADVANTAGES
Highest quality of underlying image
Very high transmittance  
   
Very high durability and reliability
DISADVANTAGES
Lower resolution than other technologies
    Surface obstructions can cause a false touch

29. DISPERSIVE SIGNAL TECHNOLOGY
This is the recent most technology, introduced in 2002.
It uses sensors to detect the mechanical (vibrational)energy in the glass that occur due to a touch.
Complex algorithms then interpret this information and provide the actual location of the touch.

30. APPLICATIONS Public Information Displays
tourism displays, trade show displays
Customer Self-Service stores, restaurants, transportation hubs, ATM and airline e-ticket terminals.
And many more uses computerized gaming, student registration systems, multimedia software, financial and scientific applications, and more.

31. CONCLUSION
Touchscreens, touch panels or touchscreen panels are display overlays which have the ability to display and receive information on the same screen.
Touchscreens also have assisted in recent changes in the PDAs, making these devices more usable.

32. THANK U
QUESTIONS?