screen technology
behind armoured glass and still work
as a touchscreen – hence the name
‘projected capacitance touch’. This type
of screen is inherently more accurate
as well as being the main type used for
vandal-proof systems.
Infrared touchscreens
Infrared touchscreens are not so
common and use an array of IR light
emitting diodes on two adjacent bezel
edges of a display, with photo sensors
on the opposite sides of the display to
analyse the system and determine a
touch event. The LED and photosensor
pairs create a grid of light beams across
the display. An object, such as a finger or
pen that touches the screen interrupts
the light beams, causing a measured
decrease in light at the corresponding
photosensors. The measured
photosensor outputs can be used to
locate a touchpoint coordinate.
Widespread adoption of infrared
touchscreens has been hampered by
two factors: the relatively high cost of
12 KIOSK solutions
the technology compared to competing
touch technologies, and the issue of
performance in bright ambient light.
However, one feature of infrared touch
remains desirable and represents
attributes of the ideal touchscreen,
which is to eliminate the glass or
plastic overlay that most other touch
technologies require in front of the
display. In many cases, this overlay is
coated with an electrically conducting
transparent material which reduces the
optical quality of the display.
The right choice
The above systems form the bulk of the
touchscreen technologies in use at the
present time and are generally widely
available. The various technologies have
different attributes and are used in
different applications, some much more
costly than others but are needed in
certain environments. Nearly all are easy
to incorporate into systems and set up
after manufacture. n