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Flat Panels: Thin Is In

Last month, I covered several significant product and technology announcements at CES 2005. While much of the press coverage of this show focused on such oddities as Samsung's 102-inch plasma TV, there were less obvious but far more important exhibits worth a second, more detailed look.

LAST MONTH, I covered several significant product and technology announcements at CES 2005. While much of the press coverage of this show focused on such oddities as Samsung's 102-inch plasma TV, there were less obvious but far more important exhibits worth a second, more detailed look.

Three in particular stood out in my mind. The first was Samsung's introduction of a 46-inch LCD TV that uses LEDs for backlights, rather than conventional cold-cathode (fluorescent) lamps. This technology promises to bring a wider and more accurate color gamut to LCD imaging — something that's essential if this technology is to replace the venerable CRT and successfully compete with plasma.

The second was the Toshiba-Canon joint venture into a new flat-panel technology, the surface-conduction electron-emitter display (SED for short). The 36-inch prototype shown at CES delivered the closest thing I've seen to CRT imaging while achieving a thin profile and low power consumption. Can it compete with LCD and plasma?

The final demonstration was tucked away in a hotel suite far from the show floor, but was well worth the trip. It detailed the ongoing development of plasma tube technology by Fujitsu (and by extension, manufacturing partner Hitachi). The plasma tube design is a radical departure from the traditional crossed ribs and “waffle” pixel structures now in common use by other plasma manufacturers.

Behind LED lighting

The use of LEDs for backlights certainly isn't a new idea; various display engineers have considered them for some time. But it took a partnership between Philips Lighting and Agilent Technologies in 1999 to bring a new company — LumiLEDs — into existence and accelerate the development of solid-state backlight technology.

The theory behind LED lighting is that the combined array of red, green, and blue LEDs has no inherent color bias, unlike fluorescent lamps. By controlling the mixture and on-off cycles of LEDs, it should be possible to achieve a high degree of accuracy when referencing standard red, green, and blue color coordinates.

LumiLEDs claims its LED backlight system can achieve 105 percent of the NTSC (SMPTE-C) color space, which would certainly make any LCD display a lot more attractive for critical video displays. The company also claims that its system can help minimize LCD motion smear (caused by a lag in the liquid crystals transitioning from one state to another) by rapid on/off switching, much the same way that a shutter works in a motion picture projector.

I can say that the Samsung demonstration of this technology, which used a live feed from an HD-resolution camera to show a series of Lava lamps in different colors, was very impressive. Amber, gold, hunter green, and turquoise are problematic colors to render with fluorescent backlights, but the images shown on the LN-460D TV were very close to the real thing.

Sony, which is a partner with Samsung in SLCD — a new joint-venture 7th-generation TFT-LCD fabrication line in Tangjung, Korea, also showed its version of this 46-inch TV, branded as the Qualia 005. Its demonstration at CES didn't have any live subjects nearby for comparison, but the quality of flesh tones and shades of subtle pastel colors in the video demo were equally impressive.

The construction of the LED stripes is also clever, and takes into account the sensitivity (or insensitivity) of the eye to the color blue. Seven rows of LEDs are arranged in a configuration with 26 red, 26 green, and 13 blue LEDs for a total of 455 individual LEDs. What's the nominal light output of this array? A tad less than 500 nits.



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