screen technology
Touchscreen
technologies
Ensure the right choice for your project as the
technologies available have their own attributes
By Kiosks4business – www.kiosks4business.com
Most common touchscreens are based
on a sheet of glass covering the display
where various technologies are applied
to the glass to arrive at the ability to
select items on a display for further
action. There are of course different
attributes to the different technologies
used for each of the touchscreen types.
The common types of touchscreen
technology are 4-wire resistive, 5-wire
resistive, capacitive, pen touch capacitive,
Surface wave acoustic, near field
imaging and Infrared. Taking each one
in turn, their method of functioning and
attributes are below:
4-wire resistive
4-wire resistive touch technology
consists of a glass or acrylic panel that’s
coated with electrically conductive and
resistive layers. The thin layers are
separated by invisible separator dots.
When operating, an electrical current
moves through the screen. When
pressure is applied to the screen as in a
touch the layers are pressed together,
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causing the resistance to change and
therefore a change in the electrical
current. This then registers as a touch
and gives its location. 4-wire resistive
type touchscreens are generally the least
costly but are generally less precise than
other types. This type of touchscreen is
generally used in more consumer type
products where the performance is less
demanding.
5-wire resistive
5-wire resistive touch technology is
constructed in a similar way to 4-wire
but is more accurate, and more durable.
5-Wire Resistive type touch screens are
generally more durable than the similar
4-Wire Resistive type. This type of screen
is generally found in demanding point
of sale systems, restaurant systems,
industrial controls, and other workplace
applications.
Surface capacitive
Surface capacitive touchscreens are
made where the base glass is coated
with a capacitive, charge storing, material
on its surface. Circuits located at corners
of the screen measure the capacitance
of a person touching the screen. As a
result of the overall capacitance of these
circuits changing; when the screen is
touched the oscillation frequency of the
circuits change and can then determine
the X and Y coordinates of the touch
event. Capacitive type touchscreens are
durable and have a high clarity. They’re
used in a wide range of applications,
from restaurant and POS use to
industrial controls and information
kiosks. Their advantages are image
clarity, not affected by dirt, grease and
moisture, and they only work by being
touched by a human finger and high
touch resolution.
Projected capacitance
Projected capacitance touchscreens
operate on a slightly different basis
where two sets of conductive layers are
etched on the glass screen such that
a series of capacitors are produced.
A human finger as it touches or gets
near these capacitors change their
capacitance thereby creating a touch
event with X and Y coordinates. The
fact that the screen capacitors change
capacitance with a finger near the screen
means that the screen can be placed