Touch Screen Technologies
There are many different types of touch screen technologies currently available, and many emerging technologies in development, but fewer than ten can be considered commercially viable at this point. In terms of market share, analog resistive is still by far the leader with well over 80% of all applications (and often cited as much more depending on the market data source and product definitions).
Analog resistive, referred to as just “resistive” from this point forward, is the workhorse of all touch screen technologies due to its low cost, acceptance of finger and stylus input, and overall ease of manufacture and integration. The main drawback of resistive touch screens is their relatively low durability and poor optics because of the standard construction of ITO coated film on ITO glass construction. The top film layer degrades with activations over time which reduces the touch screen life and the air gap between the film and bottom layers also causes the transmissivity to drop to the low-mid 80% range.
Another common touch screen technology is surface capacitive. This technology makes up a small percentage of all touch screens, traditionally with a focus in casino gaming, ATM’s and POS applications. Surface capacitive touch screens have fewer suppliers because they are relatively difficult to manufacture. A major disadvantage of surface capacitive touch screens is that they must be activated by a human finger as well as the need for periodic calibration and a good ground plane. Due to the single-layer glass construction, the transmissivity is very good at typically >90% and the durability is also very high in general.
When I use a touch screen on a kiosk, for example at an airline check-in station where most likely it is either a resistive or surface capacitive application, just for fun I’ll check to see if my fingernail or credit card will activate the touch screen. If a fingernail or credit card works, it’s a telltale sign of resistive. If not, it exhibits one of the drawbacks of surface capacitive technology. And, by this time, the people behind me are wondering what is going on – they don’t care about what type of touch screen technology the kiosk has, they just want it to work!