Touch screen technology-bharadwaj


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Touch screen technology-bharadwaj

  2. 2. Presented By SUBHAJIT BHARADWAJ 0301223250,8th sem Computer Sc.& Engg.
  3. 3. TALK FLOW <ul><li>INTRODUCTION </li></ul><ul><li>HISTORY </li></ul><ul><li>FUNCTIONS </li></ul><ul><li>WORKING </li></ul><ul><li>DIFFRENT TOUCH SCREEN TECHNOLOGIES </li></ul><ul><li>APPLICATION </li></ul><ul><li>CONCLUSION </li></ul>
  4. 4. INTRODUCTION <ul><li>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. </li></ul><ul><li>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 . </li></ul><ul><li>A touch screen accepts direct onscreen inputs. </li></ul>
  5. 5. HISTORY <ul><li>In 1971, the first &quot;touch sensor&quot; was developed by Doctor Sam Hurst (founder of Elographics) while he was an instructor at the University of Kentucky. </li></ul><ul><li>The University of Kentucky Research Foundation named it as “Elograph”. </li></ul><ul><li>The &quot;Elograph&quot; was not transparent like modern touch screens. </li></ul><ul><li>In 1974, the first true touch screen incorporating a transparent surface came. </li></ul>
  6. 6. FUNCTIONS OF TOUCH SCREEN <ul><li>Pressure sensitive activation-by finger or stylus. </li></ul><ul><li>Emulates mouse functions-click, double click, & drag. </li></ul><ul><li>Touch screen & mouse can be used concurrently. </li></ul><ul><li>Durable & scratch resistant coated surface. </li></ul><ul><li>Compatible with Windows 95,98,NT,2000,XP,Macintosh,Linux. </li></ul>
  7. 7. HOW DOES A TOUCHSCREEN WORKS? <ul><li>A basic touch screen has three main components: </li></ul><ul><li>touch sensor </li></ul><ul><li>controller </li></ul><ul><li>software driver </li></ul>
  8. 8. 1.TOUCH SENSOR <ul><li>A touch screen sensor is a clear glass panel with a touch responsive surface which is placed over a display screen. </li></ul><ul><li>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. </li></ul>
  9. 10. 2.CONTROLLER <ul><li>The controller is a small PC card that connects between the touch sensor and the PC. </li></ul><ul><li>It takes information from the touch sensor and translates it into information that PC can understand. </li></ul>
  10. 11. 3.SOFTWARE DRIVER <ul><li>The driver is a software that allows the touch screen and computer to work together. </li></ul><ul><li>It tells the operating system how to interpret the touch event information that is sent from the controller. </li></ul><ul><li>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. </li></ul>
  11. 13. DIFFERENT TOUCH SCREEN TECHNOLOGIES <ul><li>RESISTIVE </li></ul><ul><li>CAPACITIVE </li></ul><ul><li>SURFACE WAVE </li></ul><ul><li>INFRARED </li></ul><ul><li>DISPERSIVE SIGNAL TECHNOLOGY </li></ul>
  12. 14. RESISTIVE TOUCH SCREEN TECHNOLOGY <ul><li>Polyester Film . </li></ul><ul><li>Top Resistive Layer. </li></ul><ul><li>Conductive Transparent Metal Coating. </li></ul><ul><li>Bottom Resistive Layer . </li></ul><ul><li>Insulating Dots . </li></ul><ul><li>Glass Substrate </li></ul>
  13. 16. Contd. <ul><li>Pressing the flexible top sheet creates electrical contact with the coating on the glass. </li></ul><ul><li>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. </li></ul>
  14. 17. Advantages of Resistive Technology <ul><li>Can be activated with any device </li></ul><ul><li>Low cost solution </li></ul><ul><li>Low power consumption </li></ul>
  15. 18. Disadvantages of Resistive Technology <ul><li>Poorer durability compared to other technologies </li></ul><ul><li>Very short life, especially considering cosmetic wear </li></ul>
  16. 19. CAPACITIVE TOUCH SCREEN TECHNOLOGY <ul><li>In the capacitive system , a layer that stores electrical charge is placed on the glass panel. </li></ul><ul><li>When a user touches, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. </li></ul><ul><li>This decrease is measured in electrodes located at each corner of the monitor. </li></ul><ul><li>The computer then calculates the coordinates, from the relative differences in charge at each corner. </li></ul>
  17. 20. Contd. <ul><li>A finger touch draws current from each corner. </li></ul><ul><li>Then the controller measures the ratio of the current flow from the corners and calculates the touch location </li></ul>
  18. 21. Capacitive Technology <ul><li>ADVANTAGES </li></ul><ul><li>  More durable than resistive </li></ul><ul><li>Higher transmittance than resistive </li></ul><ul><li>DISADVANTAGES </li></ul><ul><li>     Accepts input from finger only. </li></ul><ul><li>                        </li></ul><ul><li>    Accuracy is dependent on capacitance of person </li></ul>
  19. 22. SURFACE WAVE TECHNOLOGY <ul><li>It has a transmitting and receiving transducers for both the X and Y axes. </li></ul><ul><li>The touchscreen controller sends a five-megahertz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass. </li></ul><ul><li>These waves are directed across the front surface of the touchscreen by an array of reflectors. </li></ul>
  20. 24. Contd. <ul><li>Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal. </li></ul><ul><li>When you touch the screen, you absorb a portion of the wave travelling across it. </li></ul><ul><li>The receivers can detect a drop in amplitude and thus coordinate is calculated. </li></ul>
  21. 25. <ul><li>ADVANTAGES </li></ul><ul><li>    Very high transmittance </li></ul><ul><li>   Very high durability   </li></ul><ul><li>DISADVANTAGES </li></ul><ul><li>  Requires “soft” input device </li></ul><ul><li>Surface obstructions can cause a false touch </li></ul>
  22. 26. INFRARED TOUCH SCREEN TECHNOLOGY <ul><li>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. </li></ul><ul><li>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. </li></ul>
  23. 28. <ul><li>ADVANTAGES </li></ul><ul><li>Highest quality of underlying image </li></ul><ul><li>Very high transmittance   </li></ul><ul><li>    </li></ul><ul><li>Very high durability and reliability </li></ul><ul><li>DISADVANTAGES </li></ul><ul><li>Lower resolution than other technologies </li></ul><ul><li>    Surface obstructions can cause a false touch </li></ul>
  24. 29. DISPERSIVE SIGNAL TECHNOLOGY <ul><li>This is the recent most technology, introduced in 2002. </li></ul><ul><li>It uses sensors to detect the mechanical ( vibrational )energy in the glass that occur due to a touch . </li></ul><ul><li>Complex algorithms then interpret this information and provide the actual location of the touch. </li></ul>
  25. 30. APPLICATIONS <ul><li>Public Information Displays </li></ul><ul><li>tourism displays, trade show displays </li></ul><ul><li>Customer Self-Service stores, restaurants, transportation hubs, ATM and airline e-ticket terminals. </li></ul><ul><li>And many more uses... computerized gaming, student registration systems, multimedia software, financial and scientific applications, and more. </li></ul>
  26. 31. CONCLUSION <ul><li>Touchscreens, touch panels or touchscreen panels are display overlays which have the ability to display and receive information on the same screen. </li></ul><ul><li>Touchscreens also have assisted in recent changes in the PDAs, making these devices more usable. </li></ul>