Specifications

15
Guided Acoustic Wave
Guided acoustic wave 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 packet
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.
When a stylus such as a finger comes
into contact with the wave, it attenuates the
wave motion by absorbing part of the wave.
Control electronics detect the location of the
dip in the wave amplitude, thus determining
the touch position.
Resistive Overlay
Resistive overlay technology consists of
a glass overlay with a thin metallic coating,
over which a layer of polyester is placed.
The polyester layer has a similar metallic
coating on the interior surface. Tiny spacer
dots of non-coated polyester prevent the two
surfaces from contacting each other. A final
hard coating is usually applied to the
external surface of the polyester to reduce
damage from sharp styli. A current is pulsed
through the glass overlay along the x-axis
and then the y-axis. When a finger or other
stylus presses the two layers together, the
current is shunted and the control electronics
determine the coordinates of the touch
location, which are then transmitted to the
host computer.