Carrol Touch TouchSystems CarrollTouch Prog, Programmer'S Manual, Page: 27 / 274

Chapter 2 - Introduction to Guided Wave Touch Systems CARROLL TOUCH
2-2 Touch System Programmer’s Guide
Overview
A Carroll Touch guided wave touch system consists of a touch
controller and touch screen. The touch system uses guided acoustic
wave (GW) technology to detect operator input for a variety of
applications. Generating invisible acoustic waves, the touch system
reports touch input when the wave motion is attenuated by a stylus
(typically a finger). This input can be used by a touch application just as
similar applications use input from pointing devices such as a mouse,
light pen or trackball.
Touch Screens
Guided acoustic wave technology is based on transmitting acoustic
waves through a glass overlay placed over the display surface. A
transducer mounted on the edge of the glass emits an acoustic wave. The
wave travels along the reflector array, is redirected across the overlay to
the reflecting edge, and returns to the array where it is reflected back to
the transducer. The first reflector will send a signal back first, then the
second, and so on, as shown in Figure 2-1.
Figure 2-1. Guided Wave Touch Screen
Touch Controllers
The touch controller is the circuitry required to create and monitor the
acoustic waves. A sequence of electrical pulses is sent to the transducer
located in the upper left of the glass overlay to generate the acoustic
waves. The area covered by the acoustic waves is the touch active area.