1. Magic of touch!!!!

2. You must have seen touch screens at ATMs, cellphones, information kiosks .Touch screen based system allows an easy navigation around a GUI based environment. 3. In1971, the first "touch sensor" was developed by Doctor Sam Hurst (founder of Elographics) Thissensor called the "Elograph" was patented by The University of Kentucky Research Foundation. In1974, the first true touch screen incorporating a transparent surface came on the scene developed by Sam Hurst and Elographics. 4. US3662105: Electrical Sensor Of Plane Coordinates Inventor(s) Hurst; George S. , Lexington, KY Parks; James E. , Lexington, KYUS3798370: Electrographic Sensor For Determining Planar Coordinates Inventor(s) Hurst; George S. , Oak Ridge, TN 5. There are four popular touch screen technologies but all of them have three main components. Touch sensitive surface The controller The software driver 6. Thetouch sensitive surface is an extremely durable and flexible glass or polymer touch response surface, and this panel is placed over the viewable area of the screen. In most sensors there is an electric signal going across the screen, and a touch on the surface causes change in the signal depending on the touch sensor technology used .This change allows the controller to identify the location of the touch. 7. Thecontroller is a device that acts as the intermediate between the screen and the computer .It interprets the electrical signal of the touch event to digital signal that computer can understand. The controller can be placed with the screen or housed externally. 8. Thesoftware driver is an interpreter that converts what signal comes from the controller to information that the operating system can understand 9. RESISTIVETOUCHSCREENS CAPACITIVE TOUCHSCREENS INFRARED STRAIN GAUGE OPTICAL IMAGING DISPERSIVE SIGNAL TECHNOLOGY ACOUSTIC PULSE RECOGNITION 10. Are composed of two flexible sheets coated with a resistive material and separated by an air gap or microdots.When contact is made to the surface of the touchscreen, the two sheets are pressed together, registering the precise location of the touch. 11. Merits: 1. works well with almost any stylus-like object. 2. more desirable than a capacitive touch screen, which has to be operated with a capacitive pointer, such as a bare finger. 3. Low cost 4. technology can be made to support multi-touch input. 12. 1.2.the user cannot press a large hand down on the screen while writing due to the nature of passive touch screen. the tradeoff is required between having a dedicated implement (stylus) versus the ability to use one's fingers as a stylus. 13. A capacitive touchscreen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). Touching the surface of the screen results in a distortion of the body's electrostatic field, measurable as a change in capacitance. 14. Surfacecapacitance. Projected capacitance. Mutual Capacitance. Self Capacitance. 15. Merits: 1. Since capacitive screens only respond to materials which are conductive (human finger used most commonly), they can be cleaned with cloths without accidental command input. 2.Are more responsive than resistive touch screen. 16. 1.A standard stylus cannot be used for capacitive sensing unless it is tipped with some form of conductive material, such as anti-static conductive foam.2.More expensive to manufacture and offer a lesser degree of accuracy than resistive touch screen.3.Capacitive touch screens cannot be used with gloves, and can fail to sense correctly with even a small amount of water. 17. An Infrared touch screen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. major benefit: can detect any input including a finger, gloved finger, stylus or pen. they do not require any patterning on the glass which increases durability and optical clarity of the overall system. 18. In a strain gauge configuration, also called force panel technology, the screen is spring-mounted on the four corners and strain gauges are used to determine deflection when the screen is touched. 19. This is a relatively modern development in touchscreen technology, in which two or more image sensors are placed around the edges (mostly the corners) of the screen. Infrared back lights are placed in the camera's field of view on the other side of the screen. A touch shows up as a shadow and each pair of cameras can then be triangulated to locate the touch or even measure the size of the touching object . 20. Introducedin 2002 by 3M, this system uses sensors to detect the mechanical energy in the glass that occurs due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. 21. claimsto provide excellent optical clarity. Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and stylus. A downside is that after the initial touch the system cannot detect a motionless finger. 22. usespiezoelectric transducers located at various positions around the screen to turn the mechanical energy of a touch (vibration) into an electronic signal. Thescreen hardware then uses an algorithm to determine the location of the touch based on the transducer signals. 23. Thetouch screen itself is made of ordinary glass, giving it good durability and optical clarity. It is usually able to function with scratches and dust on the screen with good accuracy. 24. BY: MUSTAHID ALI