If you’re old enough to remember 1990, that’s the year MC Hammer released his signature, Grammy-nominated song “U Can’t Touch This.” Hammer may have looked great rapping in parachute pants but he wasn’t that great at prognosticating. Within 15 years people were indeed touching it . . . and they were about to touch it a whole lot more after 2007, once Apple released its groundbreaking iPhone, the first handheld device ever shipped with a multi-touch display. Today, the appetite for high-quality interactive displays has spawned a massive industry with sales by 2018 expected to reach $31.9 billion. Though the display-user interface is now ubiquitous and so intuitive that even infants seem to know how to swipe left and right, we sometimes forget how truly revolutionary and disruptive this technology was when it was introduced.
Touch-device shipment and revenue will continue to rise year over year, peaking in 2019, according to market-data insight firm IHS DisplaySearch. Some touchscreens employ pressure sensors to detect contact, while some use visible or infrared light, and still others use sound waves. The broad range of environments and conditions under which the displays are deployed has required designers and manufacturers to get creative. Let’s take a look at some of the different types of touch technology, how they function, and what their advantages are in terms of reliability, durability, accuracy, size, number of touch points and, of course, cost.
Resistive Touch Screen
Resistive touchscreens are the most common and cost effective. Applications best suited to this pressure-sensitive technology are industrial, human-machine interfaces with zero tolerance for error. Because the surface responds only to direct pressure, it means users are less likely to register a false touch. The display functions well in high-traffic or rugged environments where there’s moisture or even debris, and it can independently work as LCD advertising player. And you can use it with gloves or a stylus, which makes it perfect for mining, petroleum, manufacturing, construction, and laboratory applications. Note the two types of resistive touchscreens: soft and hard surface. The soft display bears a flexible top layer of plastic ITO (indium tin oxide) film affixed over a layer of glass. In between is a crosshatch of electrode sensors that form a grid of X- and Y-axis touch points. The hard-surface display is similar but for a grid that’s sandwiched between two panes of glass, usually bezeled around the perimeter. It’s a cost-efficient technology but there are some downsides, too. Number one, the grid is an analog technology that drifts, requiring periodic recalibration. Second, the ITO film can wear and crack over time. And, finally, the screen can be difficult to read under bright light, where the image quality suffers.