Specifications

37
Figure 13 Capacitive touch screen (Reprinting Permission Requested from
3M Touch)
To differentiate all three different varieties of touch screens, the resistive touch
technology is the cheapest to purchase on the market whereas its graphics and
quality are the worst out of all of them. The next touch screen is the capacitive
touch screen and ranks in the middle in terms of cost. According to consumers
who purchase touch screen displays these are the most reliable and most
popular electronic applications on the market. Finally the surface acoustic wave
technology is the most expensive touch screen with the best picture clarity, pixel
resolution, and longer durability. Some of these touch screen technologies have
gloves to allow the user to use the screen numerous times without scratching or
damaging the glass. Even without gloves some of these technologies use special
protective coating on the glass filament layers. Table 5 shown below compares
the discussed touch screen technologies.
Technology
Resistive (4 Wire
or 5 Wire)
Surface Acoustic
Wave (SAW)
Capacitive
Transparency
75 - 85 %
85 – 92 %
85 – 92%
Accuracy
Low
Low
Moderate
Resolution
High
High
High
Touch / Input
Methods
Anything
Finger or Stylus
Finger
Durability (How
long do they
3 years for 4 Wire
5 years
2 years
Image processing
controller
Continuous imaging of
touch profile
Image of changes in
electrostatic field caused
by touch
Touch screen
(sensor)
Controller resolves touch
profile to actual touch point
Coordinates feed back to
operating system