Touch-screen panels have been around for more than a decade, but it was the 2007 introduction of a multitouch screen in Apple's iPhone that galvanized the market. Now the business is going gangbusters -- as are the innovations that touch-screen manufacturers hope will build on Apple's success.
Multitouch technology has exploded into a $6 billion business for display manufacturers this year, with more than 200 vendors vying for a piece of the action -- and it's expected to grow to more than $13 billion by 2016, according to market research firm DisplaySearch. "It's already a huge market, and growing fast," says analyst Jennifer Colegrove.
Multitouch now dominates in smartphones, and with the introduction of the iPad in 2010, multitouch helped launch the market for tablet computers. The technology is now moving into everything from larger desktop PC displays to the in-flight entertainment systems found in the seatbacks of commercial airliners -- and beyond.
A touch, not a press
Before the iPhone, most touch screens used pressure-sensitive, resistive touch panels, which required that the user physically press down on the screen. Resistive screens could track the position of just one finger at a time.
Apple chose a competing technology, projected capacitance, which responds to a light touch and can also sense a finger as it enters the electronic field above the touch surface -- a technique called proximity sensing. The touch panel sits on top of the display media (most commonly a liquid crystal display). Capacitive touch-sensing technology requires a person's finger (or a specially designed capacitive stylus) to disturb the electrical field; unlike resistive designs, it doesn't work with an ordinary stylus or other inanimate objects.
Projected capacitive screens use a glass touch surface that offers a higher level of transparency than the plastic layer used in resistive technology, resulting in brighter colors. The glass touch surface is also more durable, and capacitive technology is more forgiving of surface scratches.
Apple's major innovation with the original iPhone was figuring out how to track the actions of two simultaneous touches, which enabled the development of the iPhone's now-familiar gestures: swipe, rotate and pinch/expand. "It's really how the software is used that makes touch screens usable," says Bruce Gaunt, a mechanical engineer at Product Development Technologies, a contract engineering firm that designs and integrates touch-screen technologies for manufacturers of cell phones and laptops. "That's what Apple does really, really well."
More recently, Samsung has had success integrating multitouch technology into active-matrix organic light-emitting diode (AMOLED) screens in devices such as its Galaxy S smartphone. Branded Super AMOLED, the technology places touch sensors directly on the screen itself rather than requiring a separate layer, which makes for a thinner display.
"Samsung is a pioneer in implementing touch in active-matrix OLED displays, and more are going to follow," says Vinita Jakhanwal, an analyst at market research firm iSuppli.
Proliferation -- and limitations
This year the smartphone market will reach a crossover point, with more than 50% of units including multitouch displays on projected capacitive or OLED touch screens, says Jakhanwal. Tablet computers are another fast-growing market for multitouch, as demonstrated by the iPad's success, not to mention the slew of new tablets announced at this year's Consumer Electronics Show.
Before long, laptops with dual multitouch screens will become available, perhaps led by Acer's Iconia notebook, which is expected to ship in the first half of this year. Such designs replace the physical keyboard with a second display surface that can be used as a virtual keyboard or as an extended screen.
The device can be turned on its side, book style, to display two pages of a manuscript side by side, and users can turn the pages using a swipe gesture, as they do when reading on the iPad.
But building larger multitouch displays is more challenging, says Ken Bosley, software product manager for HP's Consumer Desktop Global Business Unit. Because the manufacture of projected capacitive technology gets expensive when scaled much beyond tablet-size screens, HP uses an optical multitouch technology, in which two cameras mounted at the screen edges determine touch coordinates, for its TouchSmart line of desktop and notebook PCs.
"There's a lot of durability issues with touch screens, and for it to work well in an upright form factor, [the unit] can't wobble or move," Bosley says. And while Apple tightly integrated multitouch technology with its operating system, Windows support is still evolving. "Windows 7 is not all that suited to touch, [so] we have worked super hard on [our] touch software," Bosley says.
Because multitouch adds about $150 to the street price of a desktop PC, Bosley says, and because it's still seen as a complement to, not a replacement for, a keyboard and mouse, some argue that multitouch is a waste of money on the desktop. A resistive touch screen would allow for basic on-screen pointing in order to, say, start playing a DVD. The problem, Bosley says, is that people now expect every touch-screen device to support multitouch, whether it benefits from the technology or not. "If you violate the expectation, it turns people off."
A prime example: The TouchSmart offers an on-screen keyboard, even though most people never use it. People prefer to use the regular keyboard, Bosley says, "but we include it because people expect it."
[Related story: Will touch screens kill the keyboard?]
Michael Woolstrom, CEO of touch-screen manufacturer Touch International, agrees. His firm is working with business partners to deliver seatback-mounted multitouch screens that will be available to replace the current generation of resistive, pressure-sensitive screens in Airbus airliners by the end of this year. "[Users] want to have the sweep, pinch and expand gestures," he says. "[Multitouch] is driving the user experience."
One big problem with vertically mounted touch-screen displays is the "gorilla arm" effect, says Andrew Hsu, technology strategist at touch-screen maker Synaptics. People simply can't work in a sustained manner with their arms extended outward -- it's too awkward and tiring.
On the TouchSmart, HP compensates for this to some degree by allowing the user to tilt the display back 30 degrees from vertical. That helps somewhat, but Bosley admits that using the touch screen at that angle is still awkward. HP's ergonomic studies show that users tend to tilt the display depending on the application, he says. Put up Solitaire, for example, and users will tilt the display back, pull it closer and use the touch screen, but they tend not to use the on-screen keyboard in this manner; with nowhere to rest your arms, it's too uncomfortable.
But on smartphones and tablets, which can be held at any angle, users are more likely to take full advantage of multitouch and to use the virtual keyboard. At this end of the market, the focus is on enhancing and expanding the multitouch experience.
Next page: More gestures on the way