Are carbon TVs the next big display technology?

[Gregg Lengling]

While the race to build bigger and cheaper LCD and plasma displays accelerates, various companies are currently trying to perfect the technology behind a new type of flat-panel display that could eventually displace today's hottest products.

The new display relies on diamonds or carbon nanotubes — two forms of pure carbon —to produce images. Theoretically, these field effect displays (FEDs) will consume less energy than plasma or liquid crystal display (LCD) TVs, deliver a better picture, and even cost less.

Tom Pitstick, vice president of marketing at Houston's Carbon Nanotechnologies, told CNET that the concept of a nanotube TV provides image quality similar to CRTs and that most of the major display manufacturers are looking at nanotube TVs.

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. Other major proponents of the technology are Canon and Toshiba.

The science behind the display FEDs is a hybrid of CRT 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 30in diagonal television is 23in deep, though slim CRTs coming next year will only need 16in 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- to 2mm rather than nearly 2ft from the target glass, and instead of one electron source — the electron gun — there is thousands. The electrons are attracted to the pixilated glass because this layer contains a positively charged anode.

FEDs consume less electricity than plasmas or LCDs because, among other factors, they contain fewer electronic parts. 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 38in across, far larger than commercially available LCDs.