Touch Screen Computer Technology

Touch Screen
Imagine a cardiac surgeon performing an intricate bypass surgery. In between, the surgeon needs to check the laboratory test results of the patient. Assuming that the information is stored on a computer, the surgeon can access the information through a keyboard, or better still, through a mouse. But how much more convenient would it be if the surgeon could only touch the screen on the option that is required to display the information. A touch screen input interface does exactly this. Touch screens are normally used when information has to be accessed with minimum effort.

Touch screens are used in information-providing systems like the one explained above. It is also used in airline and railway reservation counters. The users indicate their current location and the destination by touching the screen (maybe on a map), and all the possible routes with timings and rates are displayed. These interfaces are also used in travel agencies to display the names and address of all hotels, restaurants, and other places of interest, at a desired destination. Touch screens are also used in stock exchanges.

There are four types of touch screens. They are:
Resistive touch screens:The resistive touch screens is made sensitive to touch and the exact position is detected. This technology is recommended for use in Point of Sale, such as Hotels, Restaurants and Retail Stores. This type of touch screens is generally the most affordable.
Infrared touch screens: The infrared touch screen is lined with light emitting devices and photo-detectors. When the user's finger approaches the screens, the light beam is broken and is detected by the photo-detectors. The drawback with this technology is that your screen may sometimes react you physically touch it.

Surface Acoustic touch screens: The surface acoustic wave technology is one of the most advanced touch screen. These screens send sound waves across your screen surface to look for interruptions caused by touch. Mostly it is used for public information kiosks; computer based training, or other high traffic indoor environments.

Capacitive touch screens: The capacitive touch screen is coated with a material that stores electrical charges. When the screen is touched, the charge is drawn to the point of contact. This charge is detected and measured by the circuits located at each corner of the screen. The circuits send the information to the controller for processing. Grease, water and dirt do not affect capacitive touch screens.
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Light Pen

Light Pen







A light pen is a pointing device that can be used to select an option by simply pointing at it, or to draw figures directly on the screen.

A light pen has photo-detector at its tip. This detector can detect changes in brightness of the screen. When the pen is pointed at a particular spot on the screen, it records change in brightness instantly and informs the computer about this. The computer can find out the exact spot with this information. Thus. the computer can identify where you are pointing on the screen.

Light pens are useful for drawing graphics in programs, such as Computer Aided Design(CAD). An engineer, architect or a fashion designer can draw directly on the screen with the pen. Using a keyboard and light pen, the designer can select colours and line thickness, reduce or enlarge drawings, and edit drawings.