Touch screen technology

1. Touch screen technology Researcher: Eng. Tamer Sherif Mohamed ElMasry. Supervisor: Prof.D. Mohamed Besheer

2. What are Touch Screens? • It is the most user friendly input device used to interface with a PC. • The user touches the screen to select options presented on it, where associated hardware and software locate that touch.

3. History and Development • In 1971 Dr. Sam Hurst, founder of Elographics developed the first touch opaque sensor “Elograph” at the University of Kentucky. • In 1974 He developed the first real touch screen. • In 1977, Elographics developed the five-wire resistive technology then with the backing of Siemens Corporation, developed a curved glass sensor called the touch screen. • The new transparent technology, AccuTouch, was later developed by the founders of Elographics, Dr. Hurst and Bill Colwell.

4. Why use Touch Screens? • Enable first-time users to interface with computers instantly, without any training. • Eliminate operator errors because users make selections from clearly defined menus. • Eliminate keyboards and mice, which many novice users find difficult to use. • Rugged enough to stand up to harsh conditions where keyboards and mice can be damaged. • Provide fast access to all types of digital content. • Ensure that no space is wasted since the input device is completely integrated into the monitor.

5. Elements of a touchscreen system • The touchscreen itself. • A computer whose display is fitted with the touchscreen interefacing with. • A controller drives the touchscreen and converts each touch into X/Y coordinates. • A software driver, which communicates between the controller card and the computer's operating system. • Application-development software, which enables developers of touch programs to build their own applications and/or customize existing touch applications.

6. How do Touchscreens Work?

7. TOUCH TECHNOLOGIES Here are some technologies that are used in making touch screens: • Resistive • Capacitive • Surface Acoustic Wave (SAW) • Scanning Infrared • Near Field Imaging

8. Resistive touch screen • Made of a glass panel with a coating of uniform resistivity on which a voltage is applied. A polyester cover sheet is tightly suspended over the top of the glass, separated from it by small, transparent insulating dots. • The cover sheet has a hard, durable coating on the outer side and a conductive coating on the inner side.

9. With a light touch, the conductive coating makes electrical contact with the coating on the glass. •  The voltages at the point ofcontact are the analog representation of the position touched. The controller digitizes these voltages and transmits them to thecomputer for processing.

10. Advantages of Resistive • High Resolution and Accuracy • Fast Response • Pressure-activated by finger or gloved hand with a very light touch • Durable hard-coat front surface can be nonglare treated for     reflection control or polished for maximum clarity • Touchscreens and controllers are safety agency-approved components,so certification of your system is easier Disadvantages of Resistive • 80 % Clarity • Resistive layers can be damaged by a sharp object

11. Capacitive Touch screen • There are 2 types of capacitive touch screens: • Surface capacitive -consists of a uniform conductive coating on a glass panel on which a low voltage is evenly applied fromthe corners. -The touch location is measured from the ratio of the current flow from the corners

13. Projected Capacitive -Made of a front and back protective glass providing optical and strength enhancement options. -Its middle layer consists of a laminated sensor grid of micro-fine wires and optical enhancement options.

14. Advantages of Capacitive • High Touch Resolution • High Clarity • Completely Sealable Disadvantages of Capacitive • Must be touched by finger- will not work with any non- conductive input • Can be affected by electricity • May need re-calibration often

15. Surface Acoustic Wave Touch screen • Made of a glass overlay with transmitting and receiving piezoelectric transducers for both the X and Y axes. • When a touch occurs, the wave is absorbed shortening the echo time it takes to reach the receivers.

16. Advantages of Surface Acoustic Wave • Excellent Image Clarity -Very High LightTransmission • Excellent Durability -Stable "No-Drift" Operation • High Resolution - Very Light Touch • Fast Touch Response -X,Y and Z-axis Response • Finger or Gloved-Hand Operation Disadvantages of Surface Acoustic Wave • Must be touched by finger, gloved hand, or soft-tip stylus.  Something hard like a pen won't work • Not completely sealable, can be affected by large  amounts of grease, water,  or dirt on the touchscreen

17. Scanning Infrared touch screen • Made of a grid of LEDs and detectors framed to the front of the display that projects horizontal and vertical beams of infrared light. • The press location is determined since it obstructs the IR beam

18. Advantages • Mostly used in manufacturing and medical applications since it can be completely sealed. • operated using a stylus or a gloved finger. • mechanically stronger • Clearer • more wear resistant Disadvantages • it is very sensitive and can be activated by stray touches. • Low resolution • Parallax problems

19. Near Field Imaging touch screen • Made of two laminated glass sheets having a transparent metal oxide coating in between. • An AC signal is applied to the patterned conductive coating creating an electrostatic field on the surface of the screen. • It is used only in the toughest environments and applications due to its high cost.

20. Applications of Touch Screens • Informational kiosks • Trade show displays • Museum / tourism displays • Point-of-sale terminals • Restaurant systems • Employee time clocks • Industrial process controls • World Wide Web access kiosks • Home automation systems • Casino and other gaming systems • Computer access for the physically disabled

21. Thank you