touch screen technology report and ppt

[seminar class]

PRESENTED BY
B.LAKSHMAN

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TOUCH SCREEN TECHNOLOGY
COMPONENTS
 Three major components
 Touch sensor
 Controller
 Software driver
TOUCH SENSORS
 A touch screen sensor is a clear glass panel with a touch responsive surface.
 The touch sensor/panel is placed over a display screen.
 Sensors detects electrical current or signal.
 Touching causes a voltage or signal change, there by the location can be determined.
CONTROLLER
 The controller is a small PC card that connects between the touch sensor and the PC
 It takes information from the touch sensor
 It translates information into the PC that can understand
SOFTWARE DRIVER
 It act as a bridge between the screen and the processor
 The driver is a software that allows the touch screen and processor to work together.
 Most of the touch screen drivers today are mouse emulation type driver .
 Technologies
 Resistive Touch screen
 Surface wave Touch screen
 Capacitive Touch screen
Resistive touch screen
 Structure
Resistive touch screens consist of a glass panel that is coated with electrically conductive and resistive layers made with indium tin oxide (ITO) .The thin layers are separated by invisible spacers.
CONTROLLER
 Supply Voltage
◦ 5.0V DC
 Maximum Current
◦ 20mA
 Resolution
◦ 12-bit
SURFACE WAVE TOUCH SCREEN
SURFACE WAVE SENSORS
 Contains Transmitting and receiving transducers.
 It uses ultrasonic waves that pass over the touch screen panel.
 When the panel is touched the wave is absorbed and sends this information to the controller for processing.
CONTROLLER
 Voltage
◦ +5 VDC
 Baud Rate
◦ 9600
 Touch Resolution
◦ 12bit, size independent
◦ Conversion Time
◦ 10 ms per coordinate set
Capacitive Touch screen:
 It is a four multi-layer glass.
 A human body is an electric conductor, so when touched the screen with a finger, a slight amount of current is drawn, creating a voltage drop. The current respectively drifts to the electrodes on the four corners.
 The capacitive system has very long life (about 225 million clicks).
CONTROLLER
o Supply Voltage:
◦ +5 V DC or +12V
 Baud Rate
◦ 9600 (default) and 19200
 Touch Resolution
◦ 12bit, size independent.
 Conversion Time
◦ Approximately 15 ms per coordinate set
Advantages & Disadvantages:
Advantages:
 Fast response.
 Error free input.
 Easy to install.
 Easy to clean and maintain.
 Compatible with Windows ,and Linux.
Disadvantages:
 Finger stress: Stress on human fingers when used for more than a few minutes at a time. (for example, ATMs).
 Fingerprints: Touch screens can suffer from the problem of fingerprints on the display.
 User has to sit closer to the screen as compared to external keyboard.
 The screen may be covered more by using hand.
Applications
 General Stores
 Restaurants
 ATM’S
 Digital Computer
 Mobile Phones