5. Wacom, N-Trig and Tablet PCs

The Graphics Tablet Niche

Inside a graphics tablet

Let’s stay with purely electronic technologies — a very interesting case is the Wacom graphics tablets. The Wacom technology is similar to what’s used in capacitive screens, except that in this case it’s a disturbance in a magnetic field that’s detected. The tablet has small electric coils hidden inside it, and another coil is inserted into the body of the stylus. In operation, an alternating current circulating in the tablet’s coils generates a magnetic field. This field excites the coil in the stylus and creates a current. This is the phenomenon of induction. The stylus is actually powered by the tablet, so it can have independent buttons of its own. This technology is very precise and especially well suited to graphics tablets. However, it’s not a "tactile" screen, in strict terms, because pointing with your finger is impossible — you have to use the dedicated stylus.

For Tablet PCs Too

Beyond graphics tablets, Wacom’s EMR technology has found another application in tablet PCs: the most luxurious personal computers. In this application, the Wacom technology has a decisive advantage, because it can maintain its precision while remaining hidden under the TFT panel, which preserves the full brightness of the display. Also, the Wacom EMR technology can be combined with a traditional resistive touchscreen to get the benefit of both stylus pointing and finger pointing. This is not an ideal solution, though, since you still run into the disadvantages of resistive screens.

Wacom’s RRFC Touch technology

To avoid missing out on the touchscreen craze, Wacom has developed another technology, unveiled only recently: Reversing Ramped Field Capacitive (RRFC). This is a variant on standard capacitive screens, where instead of applying a single uniform electrical field to the surface of the screen, Wacom sets up four different fields, with gradually increasing amplitude. The existence of multiple electrical fields increases the accuracy of detection, and also reliability, especially when the computer runs on battery power. Here again, this “touch” technology can be combined with EMR, resulting in a screen that’s sensitive to both a finger and a stylus.

N-Trig – The Same Thing in Multi-Touch

The Dell Latitude XT: One of a kind

However, Wacom still doesn’t offer a "multi-touch" technology — odd for a company that has such a strong presence in the touchscreen market. And so, for its first Tablet PC — the Latitude XT — Dell gave Wacom the cold shoulder in favor of an Israeli start-up, N-Trig. In addition to being multi-touch, the N-Trig technology is hybrid, meaning that you can use your finger or a stylus. N-Trig is currently the only company on the market to offer that combination, making the Latitude XT the only PC of its type. Yet the technology behind it all seems very close to Wacom’s: an induction stylus, coupled with a capacitive screen for finger pointing. It’s a good bet that Wacom and others will soon be joining the Israeli upstart on this promising market. So much for the electronic technologies. But there are other ways to make a screen or another surface tactile, and they are based on optical detection.

Jeff Han’s FTIR

FTIR stands for Frustrated Total Internal Reflection. This technology is based on an optical phenomenon that’s well known and is used, for example, in fiber optics: total reflection. When light is propagated from one material to another, its direction changes at each interface, because materials have different refractive indexes. But for each interface, there is an angle of incidence at which rays of light are totally reflected. By emitting the beam of light at less than that angle, it’s possible to trap it inside a material.

The Magic Wall

In an FTIR touchscreen, a row of LEDs emits a beam of infrared light within the thickness of the screen’s glass pane. When you place a finger on the screen, you disturb the phenomenon of total reflection locally, since your finger reflects the infrared light differently than the ambient air does; the disturbance is detected by a camera placed behind the screen. This technology has many advantages. It’s easy to implement, low in cost, easily adaptable to very large screens, sensitive to any kind of "touch" and not subject to wear. On the other hand, the state of the surface of the screen must remain sufficiently good to maintain reflectivity.

FTIR is not yet being used in commercial products — at least not consumer products. Manufacturers and big corporations are beginning to use giant screens that implement the technology, however. For example, CNN has been using one to illustrate the results of the U.S. presidential primaries since early this year.

What’s Rare Is Costly

Jeff Han giving a demonstration at NVISION 08

This type of screen is now being marketed, among others, by Jeff Han and his company Perceptive Pixel. Han is a researcher at New York University who has become famous for videos where he’s seen in action using his FTIR touchscreens to manipulate maps and images with gestures that recall Minority Report. Thanks to that exposure and to the quality of the displays, Han has become a guru of tactile. He recently took part in the NVISION trade show alongside Jen Hsun Huang.

For the record, if you feel you just have to have a screen like this in your home theater room, you can order one from Neiman Marcus — for a mere $100,000. Fortunately for those of us who can’t quite swing that, you can get something almost as good for a good deal less.