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Touch screen technology


Touch screen technology Researcher: Eng. Tamer Sherif Mohamed ElMasry. Supervisor: Prof.D. Mohamed Besheer What are Touch Screens? It is the most user friendly input ... – PowerPoint PPT presentation

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Title: Touch screen technology

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

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.

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.

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
  • Ensure that no space is wasted since the input
    device is completely integrated into the monitor.

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
  • Application-development software, which enables
    developers of touch programs to build their own
    applications and/or customize existing touch

How do Touchscreens Work?
  • Here are some technologies that are used in
    making touch screens
  • Resistive
  • Capacitive
  • Surface Acoustic Wave (SAW)
  • Scanning Infrared
  • Near Field Imaging

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.

  • 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 the computer for processing.

  • 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

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

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

  • 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

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

  • Advantages of Surface Acoustic Wave
  • Excellent Image Clarity -Very High
  • Excellent Durability -Stable "No-Drift"
  • 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
  • Not completely sealable, can be affected by
    large  amounts of grease, water,  or dirt on the

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

  • 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

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.

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

Thank you