Touch screen echnology


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introductory part of touch screen technology

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Touch screen echnology

  1. 1. introduction     Whether it’s on a mobile device, tablet, or medical device, technology in the field of electronics give tremendous revolution in passed decades. One of the revolution can be easily seen in screen that plays an important role in making devices highly usable as it helps in direct interaction of user with the device but there exist difficulty in using input devices such as a mouse or keyboard (key pad). Now the scenario has changed and we have a new technology in screen called Touch Screen Technology which provide a natural interface with the device This technology means as simple as its name that is Touch the Screen and Activate Instructions (TSAI). Instead of the keyboard (keypad) or mouse we can operate or stimulate an instruction or command by touching on the screen
  2. 2.  1960s First touch screen to be a capacitive touch screen invented by E.A. Johnson at the Royal Radar Establishment, Malvern, UK, around 1965 – 1967  1990s The nineties introduced smart phones and handhelds with touch screen technology. In 1993, Apple released the Newton PDA, equipped with handwriting recognition; and IBM released the first smart phone called Simon, which featured a calendar, note pad, and fax function, and a touch screen interface that allowed users to dial phone numbers.  2000s In 2002, Microsoft introduced the Windows XP Tablet edition and started its entry into touch technology
  3. 3.  Capacitive Touch Screen  Resistive Touch Screen  Acoustic touch Screen  Infrared touch Screen  Optical Touch Screen  Dispersive Touch Screen
  4. 4. Touch Screen – Construction & working Contruction The key goals (while making touch ) are to recognize one or more fingers touching a display, to interpret the command that this represents, and to communicate the command to the appropriate application. In the most popular techniques, there are typically four layers:  Top polyester coated with a transparent metallic conductive coating on the bottom  Adhesive spacer  Glass layer coated with a transparent metallic conductive coating on the top  Adhesive layer on the backside of the glass for mounting.
  5. 5. Working There are three components used in touch screen technology for its working  Touch Sensor:- A touch screen sensor is a clear glass panel with a touch  Controller:- The controller, is the hardware that connects between the touch sensor and the  Software:- Software contains drivers that allows the touchscreen and computer to work responsive surface. The touch sensor/panel is placed over a display screen so that the responsive area of the panel covers the viewable area of the video 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. PC or other devices. It converts the voltage changes on the sensor into signals and translates it into information that PC or other devices can understand. Controller is usually installed inside the monitor (or screen of other devices) or it is housed in a plastic case for external touch addons/overlays together and tells the computer, smartphone, game device, etc, what's happening on the sensor and the information coming from the controller. Who's touching what where; and allows the computer or smart phone to react accordingly.
  6. 6. Types of Touch  Single Touch Single Touch occurs when a finger or stylus creates a touch event on the surface of a touch sensor or within a touch field so it is detected by the touch controller and the application can determine the X,Y coordinates of the touch event. Single touch using finger Single touch using stylus
  7. 7.  Multi-Touch The term "multi-touch" is now in common use to describe any touch screen that can recognize more than one point of contact; in effect the use of two or more fingers simultaneously
  8. 8. Resistive Touch Screen  Resistive LCD touchscreen monitors rely on touch overlay, which is composed of a flexible top layer and a rigid bottom layer separated by insulating dots, attached to a touchscreen controller.  The inside surface of each of the two layers is coated with a transparent metal oxide coating of Indium Tin Oxide (ITO) that facilitates a gradient across each layer when voltage is applied.  Pressing the flexible top sheet creates electrical contact between the resistive layers, producing a switch closing in the circuit. The control electronics alternate voltage between the layers and pass  the resulting X and Y touch coordinates to the touchscreen Controller.  The touchscreen controller data is then passed on to the computer operating system for processing.
  9. 9.  Resistive Technology is divided into two broad categories: • Four-wire resistive technology :- It uses both the upper and lower layers in the touchscreen "sandwich" to determine the X and Y coordinates. Typically constructed with uniform resistive coatings of ITO on the inner sides of the layers and silver buss bars along the edges, the combination sets up lines of equal potential in both X and Y.
  10. 10. Four wire Resistive Touch screen  In the illustration below, the controller first applies 5V to the back layer. Upon touch, it probes the analog voltage with the coversheet, reading 2.5V, which represents a left-right position or X axis.  It then flips the process, applying 5V to the coversheet, and probes from the back layer to calculate an up-down position or Y axis.  At any time, only three of the four wires are in use.
  11. 11. 5-Wire Resistive Touchscreen  In the five-wire design, one wire goes to the coversheet (E) which serves as the voltage probe for X and Y.  Four wires go to corners of the back glass layer (A, B, C, and D). The controller first applies 5V to corners A and B and grounds C and D, causing voltage to flow uniformly across the screen from the top to the bottom.  Upon touch, it reads the Y voltage from the coversheet at E. Then the controller applies 5V to corners A and C and grounds B and D, and reads the X voltage from E again.
  12. 12. ADVANTAGES DISADVANTAGE Value solution Reduced optical clarity Activated by any stylus or finger or glove inputs Polyester surface can be damaged High touch point resolution Low cost sensors & power requirements Not affected by dust or water Extremely durable Requires bare finger or capacitive stylus Very accurate Scratch can affect operation Good optical clarity Good resolution
  13. 13. Capacitive Touch Screen  A capacitive touch screen panel is coated with a material (metal oxide ) that stores electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact.  Circuits located at each corner of the panel measure the charge and send the information to the controller for processing.  Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus.
  14. 14.  Surface capacitive technology In this technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied to the layer, resulting in a uniform electrostatic field. When touches surface a capacitor is dynamically formed. The sensor's controller can determine the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel. it is moderately durable, has limited resolution and is prone to false signals from parasitic capacitive coupling. It is therefore most often used in simple applications such as industrial controls and kiosks  Projected capacitive technology Projected Capacitive Touch (PCT) technology is a capacitive technology which permits more accurate and flexible operation, by etching the conductive layer. An X-Y grid is formed. A finger on a grid of conductive traces changes the capacitance of the nearest traces. This change in trace capacitance is measured and finger position is computed. The use of an X-Y grid permits a higher resolution than resistive technology. Projected capacitive touch screens are clear, durable, solid state, scratch resistant and allow gloved hand use.
  15. 15. Fig. Capacitive Touch Screen
  16. 16.  Because of its high optical clarity and accuracy, acoustic wave technology is typically used in kiosk applications.  Acoustic wave touch screens use transducers mounted at the edge of a glass overlay to emit ultrasonic sound waves along two sides. These waves are reflected across the surface of the glass and received by sensors. A finger or other soft tipped stylus absorbs some of the acoustic energy and the controller measures the amplitude change of the wave to determine touch location.
  17. 17. Fig. Acoustic Touch Screen
  18. 18.  Infrared touch screens are primarily used for large displays, banking machines, and in military applications.  Infrared touch screens are based on light-beam interruption technology. Instead of an overlay on the surface, a frame surrounds the display. The frame has light sources, or light emitting diodes (LEDs) on one side and light detectors on the opposite side, creating an optical grid across the screen. When an object touches the screen, the invisible light beam is interrupted, causing a drop in the signal received by the photo sensors.
  19. 19. Fig. Infrared Touch Screen
  20. 20. Optical Touch Screens  Optical touch screen technology is ideal for large LCD and plasma displays up to 100" diagonal. Optical touch screen technology uses two line scanning cameras located at the corners of the screen.  The cameras track the movement of any object close to the surface by detecting the interruption of an infrared light source.  The light is emitted in a plane across the surface of the screen and can be either active (infra-red LED) or passive (special reflective surfaces).
  21. 21. Fig. Optical Touch Screen
  22. 22. Dispersive Introduced in 2002 by 3M, this system uses sensors to detect the Piezoelectricity in the glass that occurs due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to 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.
  23. 23. Fig. Dispersive Touch Screen
  24. 24. Advantages & Disadvantages of other touch screens ADVANTAGES Acoustic Infrared Dispersive Good optical clarity Accurate excellent optical clarity Z-axis capability No overlay, unaffected by dust Durable glass front Superior image, mechanical vibrations are used to detect a touch event DISADVANTAGES Acoustic Infrared Requires finger or sound absorbing stylus Costly Difficult to industrialize Low reliability Signal affected by surface liquids Parallax problems Prone to scratches easily Accidental activation
  25. 25. Public Information Displays  Tourism displays,  trade show displays,  Information kiosks Retail and Restaurant Systems  valuable counter space can be saved  cash registers,  seating, reservation systems  Item selection Control and Automation Systems  In real-time by simply touching the screen and with a  graphical interface, operators can monitor and control complex  operations. Assistive Technology  Personal Digital Assistants (PDAs). Other applications include  Digital jukeboxes,  Computerized gaming, student registration systems,  Multimedia software,  Financial and scientific applications  Smart classes
  26. 26. MARKET OVERVIEW OF TOUCH SCREENS  The touch screen market's dynamics are altered by growing shipment of Apple's iPhone and iPod and recently the iPad. Projected capacitive touch technology is found to be more adopted in mobile phones and tablets, Display Search forecasts that projected capacitive will pass resistive touch technology to become the leading touch technology in 2010, measured by revenues.
  27. 27. Advances in technology   Touchscreens can suffer from the problem of fingerprints on the display. This can be mitigated by the use of materials with optical coatings designed to reduce the visible effects of fingerprint oils, or oleophobic coatings as used in the iPhone 3GS,. Using a chemical found in paint, called titanium dioxide .When exposed to sunlight creates a "chain reaction that creates free radicals, which penetrate the cell walls of bacteria and fungi and damager their DNA."
  28. 28.   Samsung's new transparent and flexible AMOLED screens, you'll love 3M's new transparent and flexible multi-touch surface 3M has developed a new type of touchscreen system that's flexible, very thin, totally transparent, durable, and capable of resolving more touch points than you have fingers (and toes). a flexible touchscreen bracelet phone could be a reality, Touch screen bracelet Flexible & transparent Touch screen
  29. 29. Future Scope  More advanced technology like the one from Japanese Company Wacom, would bring multitouch capabilities where people can work on more than on object simultaneously.  Work is still going on to make highly reliable , durable, responsive , scratch and water proof multitouch touchscreen that can work with both hands (simultaneously) of the user with great coordination  Touch Screen capability enhance real and natural feeling of working with pc or other devices for example Drag and drop with touch is more real rather than with input devices like mouse .  The future of touch surface is touchscreen video projectors. In a restaurant, for e.g., you can place your order using the surface of the table as the touch interface, instead of using a touch screen laptop. The ability to transform any surface in a touchscreen means lower costs, making the technology more cost effective.
  30. 30. Thank You