Touchscreens : Understanding touchscreen technology and design
Touchscreens (sometimes spelled as touch screen) are everywhere: they are embedded in phones, office equipment, speakers, digital photo frames, TV control buttons, remote controls, GPS systems, automotive keyless entry, and medical monitoring equipment. As a component, they have reached into every industry, every product type, every size, and every application at every price point. In fact, if a product has an LCD or buttons, a designer somewhere is probably evaluating how that product, too, can implement touchscreen technology. As with any technology, there are many different ways to implementation approaches, many promises of performance, and many different technical considerations when designing a touchscreen.
Since projected-capacitive panels have multiple sensors, they can detect multiple fingers simultaneously, which is impossible with other technologies. In fact, projective capacitance has been shown to detect up to ten fingers at the same time. This enables exciting new applications based on multiple finger presses, including multiplayer gaming on handheld electronics or playing an touchscreen piano.
The most widely used touchscreen technology is resistive. Most people have used one of these resistive touchscreens already, in the ATM at the bank, in the credit card checkout in most stores, or even for entering an order in a restaurant. Projective-capacitance touchscreens, on the other hand, are not as broadly available yet, but are gaining market momentum. Many cellphones and portable music players are beginning to come to market with projective-capacitance interfaces. Both resistive and capacitive technologies have a strong electrical component, both use ITO (Indium-Tin-Oxide, a clear conductor), and both will be around for a long time to come.