Carbon TVs to edge out liquid crystal, plasma?

If you've bought a plasma TV, you might get one-upped in two years, when TVs using new carbon technology arrive.

Tech Culture
You can find carbon in coal and tennis rackets, and a few years from now, it could run your TV.

Various companies are currently trying to perfect the technology behind a new type of flat-panel display that will rely on diamonds or carbon nanotubes--two forms of pure carbon--to produce images.

Theoretically, these "field emitter displays," or FEDs, will consume less energy than plasma or liquid crystal display (LCD) TVs, deliver a better picture and even cost less. The development of FEDs underscores the rapid changes taking place in what had been a relatively staid TV market.

Once dominated by a few Japanese manufacturers, the television market now includes a wide variety of companies, including Dell, Hewlett-Packard and Westinghouse. If successful, FEDs could even render the new TVs being shown off this week at the Consumer Electronics Show (CES) in Las Vegas as has-beens.

"The concept of a nanotube TV will give you image quality similar to CRTs (cathode ray tubes), and the best image quality is still found on CRT TVs," said Tom Pitstick, vice president of marketing at Houston's Carbon Nanotechnologies. "All the major display manufacturers are looking at nanotube TVs."

Electronics giant Samsung has already produced a prototype of a TV-size display made with CNI's nanotubes. Televisions based on the new screens will nudge onto shelves in late 2006, he added.

Meanwhile, Advance Nanotech, in collaboration with the University of Bristol, is developing a similar panel that relies on specially doped diamond dust. The company hopes to have working prototypes in 18 months to two years.

So far, some of the biggest proponents of this approach could be Canon and Toshiba. The two manufacturers have formed a joint venture to make surface conduction electron emission (SED) panels, and Toshiba will produce large-screen SED televisions in 2006. Although Canon and Toshiba's description of SEDs is very similar to that of FEDs, the two companies are using a different particle than carbon, industry analysts said.

Technological hurdles remain, and delays are also inevitable. In 2003, some said nanotube-based televisions could possibility come out in 2005.

But that goal is still a pipe dream for many. Candescent, for example, once touted as America's re-entry into the display industry, burned through $600 million in funding before abandoning plans to produce FEDs made with materials other than carbon in 2001. It sold its assets to Canon in August 2004, two months after filing for voluntary reorganization under Chapter 11.

Then there is the problem of previous investment. "It is hard to imagine you can break into an industry where LCD investment is going like crazy," said Paul Semenza, vice president of display research at iSuppli. "It is hard to be optimistic."

Matthew Nordan of Lux Research agreed, predicting that companies may hold off until 2006 to build plants for mass production of nanotube-based televisions starting in 2008 or 2009.

The science behind the display
FEDs, in a sense, are a hybrid of CRT televisions and LCD televisions. In a CRT, an electron gun at the back of a large vacuum tube shoots electrons at a piece of phosphor-coated glass divided into points. The phosphor creates light from the energy of the electrons, and the light that emerges on the other side of the glass forms the picture.

An LCD panel, by contrast, is created by sandwiching layers of components, such as transistors, crystal silicon and various filters, between two pieces of glass. Images are displayed when an electrical charge is sent through the panel, shifting the positions of the crystals. A light source behind the panel brightens the image and the pixels, depending on their positions, and blocks light or permits it to pass through, creating an image.

The images produced by CRT tubes are crisper and aren't subject to the shifting and ghosting of LCD screens. However, the electron gun in CRTs requires a large vacuum: the tube in a 30-inch diagonal television is 23-inches deep, though slim CRTs coming next year will only need 16-inch deep tubes.

Like an LCD, an FED is made up of layers. A layer of glass is coated with a cathode and a layer of diamond dust coated with lithium or carbon nanotubes. The negatively charged cathode, organized in a grid, then emits electrons through the diamonds or nanotubes, which focus that energy like a tiny lightening rod.

But then, like a CRT, the electrons shoot through a vacuum at a layer of phosphorescent glass covered with pixels. The big difference is that the source of electrons, the carbon, is located only 1 millimeter to 2 millimeters rather than nearly 2 feet from the target glass, and instead of one electron source--the electron gun--there are thousands. The electrons are attracted to the pixilated glass because this layer contains a positively charged anode.

"This generates light the same way a CRT tube does," said Pitstick, leading to similar picture quality. At the same time, a FED is only slightly thicker than an LCD panel.

Advance Nanotech spokeswoman Liza Mullins described it in lunch terms. "There are two layers of glass (the bread in the sandwich), and some layers of thin material deposited in the inner side of each (butter on the bread), and a near-vacuum gap," she wrote in an e-mail.

FEDs will consume less electricity than plasmas or LCDs because, among other factors, they will contain fewer electronic parts, Pitstick said. Costs will also decline over time because fairly simple manufacturing processes are used, and FEDs contain fewer chips.

Size isn't an issue: A 2004 prototype of a nanotube FED measures 38 inches across, far larger than commercially available LCDs. FEDs, in fact, largely will be incorporated into televisions and large computer monitors, Pitstick said. Toshiba's SED televisions will start at 50 inches. Advance, however, said the technology could be used in screens ranging from 2 inches to 100 inches in diameter.

The diamonds or nanotubes do not need to be precisely positioned. Instead, both are scattered randomly in the coating, like sugar crystals in coffee, but enough exist in the mix to ensure that each points in the right direction to transmit electrons.

The diamonds are deposited as evenly as possible over the lower layer. "Only those particles which have an emitter structure behind them actually participate in the display function," Mullins said.

But getting all of the parts to work well together could be a challenge. The companies have to devise coatings that will let the carbon adhere to the glass. More work needs to be accomplished on the electrodes as well.

"All of these technologies have to control a vacuum with a thin cell size over a large area," iSuppli's Semenza said. Nonetheless, "it is probably prudent for these guys (large manufacturers) to have people working on this."

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