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Multi-Touch technology.


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Multi-Touch technology.

  1. 1. SEMINAR ON “MULTY-TOUCH TECHNOLOGY” Dept. of Electronics And Telecommunication Engineering, SSGMCE, Shegaon. Presented by: Guided by: ANURAG N. CHATAP Roll no.- 43(4U1) PRGO9 Prof. D. L. BHOMBE 16-Feb-14 SSGMCE, Shegaon 1
  2. 2. MULTI-TOUCH TECHNOLOGY 16-Feb-14 SSGMCE, Shegaon 2
  3. 3. CONTENT Introduction to Multi-touch technology  Why multi-touch technology is used?  Types of Touch Technologies  Frustrated Total Internal Reflection (FTIR)  Applications  Advantages  Disadvantages  Conclusion  references  16-Feb-14 SSGMCE, Shegaon 3
  4. 4. Introduction      Multi-touch is a human-computer interaction technique. Consists of a touch screen as well as software that recognizes multiple simultaneous touch points. Multi touch using Frustrated Total Internal Reflection Enables high-resolution multi touch sensing on rear-projected interactive surfaces. interact with more than one finger at a time and also able to accommodate multiple users simultaneously 16-Feb-14 SSGMCE, Shegaon 4
  5. 5. Why multi-touch? Allows a user to interact with a system with more than one finger at once Operations using both hands Also allows multiple users to interact on the same touch-sensitive platform Interactive walls Interactive tabletops 16-Feb-14 SSGMCE, Shegaon 5
  6. 6. Types of touch technologies There are mainly three types of touch Technologies:1.Resistive 2. Capacitive 3. Surface acoustic wave 16-Feb-14 SSGMCE, Shegaon 6
  7. 7. Resistive touch screens Two layers of conductive material  Touch creates contact between resistive layers completing circuit  16-Feb-14 SSGMCE, Shegaon 7
  8. 8. Resistive touch screens  Voltage in circuit changes based on position  Controller determines location based on voltages  Any material can trigger sensors 16-Feb-14 SSGMCE, Shegaon 8
  9. 9. Advantages & Disadvantages of Resistive   Advantages ◦ Cost-effective solution ◦ Activated by any stylus ◦ Very accurate ◦ Low power requirements ◦ Liquids won't affect touch screen performance Disadvantages ◦ Polyester surface can be damaged ◦ Only 75% light transmission ◦ Lower endurance (~35 million touches) 16-Feb-14 SSGMCE, Shegaon 9
  10. 10. Capacitive Touch Screens  Glass panel with conductive layer (Indium Tin Oxide)  Small amount of voltage applied to four corners of touch screen [2] 16-Feb-14 SSGMCE, Shegaon 10
  11. 11. Capacitive Touch Screens  Touch draws minute amount of current creating voltage drop  Coordinates of point of contact calculated by controller [2] 16-Feb-14 SSGMCE, Shegaon 11
  12. 12. Advantages & Disadvantages of Capacitive   Advantages ◦ Scratch resistant, durable surface ◦ High endurance (225 million touches) ◦ Very accurate ◦ Good optical clarity ◦ Liquids won't affect touch screen performance Disadvantages ◦ Does not work with gloved fingers or stylus 16-Feb-14 SSGMCE, Shegaon 12
  13. 13. Surface Acoustic Wave (SAW)  Surface consists of glass overlay with transmitting and receiving transducers 16-Feb-14 SSGMCE, Shegaon 13
  14. 14. [2]   Electrical signals sent to the transmitting transducers converts to ultrasonic waves Waves are directed across screen by reflectors then directed to receiving transducers 16-Feb-14 SSGMCE, Shegaon 14
  15. 15. [2]   When finger touches screen it absorbs waves Received values are compared to stored digital maps to calculate x and y coordinates 16-Feb-14 SSGMCE, Shegaon 15
  16. 16. Advantages & Disadvantages of SAW   Advantages ◦ Durable glass construction ◦ High optical clarity ◦ Activated by a finger, gloved hand, or soft tip stylus Disadvantages ◦ Moving liquids or condensation can cause false touches ◦ Solid contaminants create non-touch areas until removed ◦ Doesn't support drag or draw effectively 16-Feb-14 SSGMCE, Shegaon 16
  17. 17. Touch Screen Technology Comparison Chart 16-Feb-14 SSGMCE, Shegaon 17
  18. 18. Pointing Device Gestures    Cursor movements as command shortcuts Takes place of keyboard shortcuts Useful in applications where keyboard use is less prominent or undesirable Above: Some possible cursor movement patterns for use in gesture support. 16-Feb-14 SSGMCE, Shegaon 18
  19. 19. Example Fig. 3 – After vectorization Fig. 1 – User input Fig. 2 – Captured/filtered pointer data Fig. 4 – Final matching result 16-Feb-14 SSGMCE, Shegaon 19
  20. 20. Frustrated Total Internal Reflection (FTIR)     If the angle of incidence is greater than the critical angle, then the light will stop crossing the boundary and be totally reflected back internally. This occur when light travels from a medium with a higher refractive index to one with a lower refractive index. If a third medium with a higher refractive index than the second medium is placed and it will pass energy across the second into the third medium. evanescent wave travel along the boundary between the two materials. This wave leads to a phenomenon known as frustrated total internal reflection. 16-Feb-14 SSGMCE, Shegaon 20
  21. 21. How is projection achieved? 16-Feb-14 SSGMCE, Shegaon 21
  22. 22. Using FTIR for touch sensitivity     A clear acrylic sheet is used as the touch surface. ◦ 16 inches x 12 inches in prototype Edges of surface lit by infra-red LEDs to produce total internal reflection. A video camera is mounted under the surface and facing it. When the surface is touched, the light escapes and registers on the camera. 16-Feb-14 SSGMCE, Shegaon 22
  23. 23. Using FTIR for touch sensitivity  Basic image-processing techniques are performed on the camera output to identify the points of contact.  Computer-vision techniques are used to interpret the motion of contact points as discrete touches or strokes.  Processing easily handled in real-time by a 2 GHz Pentium IV processor 16-Feb-14 SSGMCE, Shegaon 23
  24. 24. Application         Personal computers, Laptops, Tabletops, Graphics Tablets It supports both LCD and CRT monitors. Telephones, Watches, PDAs, Mobile phones. Advanced multi touch Gaming with high graphics support Governmental, office and business purposes An enhanced multimedia experience including audio, vide and photo sharing Enhanced dining experience Concept mapping 16-Feb-14 SSGMCE, Shegaon 24
  25. 25. Disadvantages Requires significant space behind touch surface for camera  Gloves, certain types of styluses, and even dry skin may not register ◦ a function of refractive index  Residues on surface (e.g., sweat) also produce FTIR effect that may build up  16-Feb-14 SSGMCE, Shegaon 25
  26. 26. Conclusion There are many ways to make a multi-touch screen. Some of the early designs measured the change in electrical resistance or capacitance on a surface when fingers touched it. But these devices have limited resolution, are relatively complex, and don't easily and inexpensively scale up to large dimensions. This technique using FTIR is simple and easy to implement. It provides any resolution displays supported with high graphics .The applications being both made and proposed are plenty in number. 16-Feb-14 SSGMCE, Shegaon 26
  27. 27. REFERENCES • B. Buxton, "Multi-Touch systems that I have known and loved," Microsoft Research, 2009. • 0.J. Kim, J. Park, H. K. Kim, and C. Lee, "Hci (Human Computer Interaction) using multi-touch tabletop display," 2007. • S. Do-Lenh, et al., "Multi-Finger interactions with papers on augmented tabletops," in Proceedings of the 3rd International Conference on Tangible and Embedded Interaction. 2009, ACM: Cambridge, United Kingdom. • American scientists -hands-on computing: How Multi-Touch screens could change the way we interact with Computers & each other 16-Feb-14 SSGMCE, Shegaon 27
  28. 28. Click here to watch video 16-Feb-14 SSGMCE, Shegaon 28
  29. 29. Thank YOU 16-Feb-14 SSGMCE, Shegaon 29