 - A touch screen is a computer display screen that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen. Touch screens are used with information kiosks,
computer-based training devices, and systems designed to help individuals who
have difficulty manipulating a mouse or keyboard. Touch screen technology can be used as an alternative user interface with applications that normally require a mouse, such as a Web browser. Some applications are designed specifically for touch screen technology, often having larger icons and links than the typical PC application. Monitors are available with built-in touch screen technology or individuals can purchase a touch screen kit.
A touch screen kit includes a touch screen panel, a controller, and a
software driver. The
touch screen panel is a clear panel attached externally to the monitor that
plugs into a serial or Universal Serial Bus (USB) port or a
bus card
installed inside the computer. The touch screen panel registers touch events and passes these signals to the controller. The controller then processes the
signals and sends the data to the processor.
The software driver translates touch events into mouse events. Drivers can be provided for both Windows and Macintosh operating systems.
Internal touch screen kits are available but require professional installation
because they must be installed inside the monitor.
There are three types of touch screen technology:
- Resistive: A resistive touch screen panel is coated with a thin
metallic electrically conductive and resistive layer that causes a change in
the electrical current which is registered as a touch event and sent to the
controller for processing. Resistive touch screen panels are generally more
affordable but offer only 75% clarity and the layer can be damaged by sharp
objects. Resistive touch screen panels are not affected by outside elements
such as dust or water.
- Surface wave: Surface wave technology uses ultrasonic waves that
pass over the touch screen panel. When the panel is touched, a portion of the
wave is absorbed. This change in the ultrasonic waves registers the position
of the touch event and sends this information to the controller for
processing. Surface wave touch screen panels are the most advanced of the
three types, but they can be damaged by outside elements.
- Capacitive: A capacitive touch screen panel is coated with a
material 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.
Capacitive touch screens are not affected by outside elements and have high
clarity.
| CONTRIBUTORS: |
Manik Junja |
| LAST UPDATED: |
18 Jun 2001
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