A touch panel or touch screen is a touch-sensitive transparent
screen mounted in front of an LCD. It provides a way for a person to interact
with an electronic system. Typically the system will display several icons on
the LCD and expect the user to select one by touching it. The touch causes some
measurable phenomena which is converted by a controller IC into screen
coordinates which are sent into the system. The system then determines which
icon was selected and takes appropriate action. The phrases Touch Screen and
Touch Panel mean the same thing and are interchangeable.
S-Tek is an
Agent for is the main supplier of touch screens in the field of PDAs and
calculators. Small TN, STN LCDs are especially well suited for handheld devices,
where interaction is required but keyboards are impractical Touch screens are so
often used.
There are several physical phenomena which can be used to
detect a touch including capacitive, infrared, resistive and surface acoustic
wave (SAW). Resistive touch screens are the most common because they are simple,
low cost and can be activated by finger tip or any type of stylus. Most of
Orient Display products are resistive type. Capacitive technology offers higher
transparency at a higher cost. Surface acoustic wave technology requires more
border, more power and a touch by finger, but gives more durability for public
access applications. Among resistive touch screens, the 4 wire method is most
common, and the 5 wire less so. 8 wire resistive is a variation on 4 wire and 6
wire and 7 wire are variants of the 5 wire method.
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