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.
Projected Capacitive Touch Screen
Unlike resistive touch, which relies on pressure, projected

capacitive touch

screens rely on shifting electrical charges instead of moving parts. If you’ve

ever worn socks on carpeting in winter then touched a metal object and gotten a shock,

you’ve experienced electrical capacitance. PCAP technology involves two conductive

layers that create an electrostatic field, which transfers energy when contacted. One of

the key benefits is its ability to process multiple touch points simultaneously. Another

great thing is, by eliminating the layers of film and glass PCAP offers near-perfect

optical clarity and performance. It’s one of the main reason so many smart phones use

it. It tends to be more expensive than resistive touch but its optical clarity, power

efficiency and aesthetics have made it the go-to technology for tablets and phones.

Because its images are accurate and contrast ratios high, it’s also popular in medical

imaging and other industries where an onscreen blotch or defect could lead to

catastrophic results. An optional ‘optical bonding’ feature recommended by Premio,

which eliminates air and moisture between the layers, makes for an even clearer and more

rugged display that withstands shocks and vibrations. A downside is PCAP’s

susceptibility to ‘noise’ generated by electromagnetic interference (EMI). Because the

display must be finely calibrated to ignore nearby EMI noise, users have to operate PCAP

with a finger rather than fingernail, gloved finger or stylus.
Surface Acoustic Wave Touch Screen
Surface acoustic wave (SAW) touch technology uses a transducer to record the

absorption of ultrasonic waves transmitted across the display’s surface. Superior

clarity and resolution make SAW ideal for in-door applications that require precision

image quality as in devices used for research and monitoring. The technology primarily is

used with smaller touchscreens of up to 32 inches. Other suitable in-door uses include

ATMs and information kiosks, such as self service kiosk. Key advantages include high-

durability glass, superior optical clarity, and broader activation capabilities using

finger, gloved-finger or soft-tip stylus. Vulnerabilities include moving liquids or

condensation that produces false touches, solid stains that cause non-responsiveness

until cleaned, and less-robust drag and draw capabilities.
Optical Infrared IR Touch

Screen
Owing to its flexibility, optical infrared (IR) is another highly popular technology.

Notably, IR is the only touchscreen that operates without a film or glass cover layer.

Instead it relies on infrared light-emitting diodes projecting an invisible grid of beams

that register touch wherever light is disrupted. It offers great clarity, is easy to

calibrate, and lasts a long time, too, since there’s no flexible layer to degrade over

time. The main drawback is the presence of a noticeable gap between flat panel and IR

sensors. For this reason it’s less suited for industrial and highly trafficked

applications where high-pressure dust, debris or liquid might harm the electronics inside

the LCD panel. The optics are clearer than resistive or capacitive touch, it provides a

rugged surface that manufacturers can bezel and seal against dust and moisture, and it

supports multi-touch and dual-touch inputs. Produced mainly at sizes larger than 32

inches, IR technology is ideally suited for use with kiosks, or

self service machine, outdoor

installations, point-of-sale systems, factory automation, and other applications where

bare fingers are impractical – from industrial and pharmaceutical environments to

retail, hospitality, and service industries.
The Premio Touch
Although MC Hammer couldn’t have foreseen that U touching it would be so easy, he

might’ve guessed that the technology behind it would be so sophisticated. Before

investing in any industrial display, however, first we have to weigh the pros and cons of

functionality, durability, aesthetics and cost. We also have to consider the time and

effort required to maintain and calibrate the device so that it performs optimally in its

particular industrial environment. Fortunately, Premio specializes in helping clients

identify the right technology for the job. With a Class 10,000, dust-controlled clean

room dedicated to touch-sensor lamination at our headquarters in Greater Los Angeles,

Premio offers extensive expertise integrating and manufacturing award-winning, touch-

enabled products for a broad range of industrial uses. In fact, we’ve been providing

solutions for original equipment and design manufacturers for more than 28 years.