Lighting the way to TV differentiation
Dec 06, 2007
New technologies for television backlighting point to better performance, new products
LCD TV makers are striving to differentiate their products and move the market to ever-larger screen sizes, while rear-projection TV makers are trying to remain competitive against flat-panel TVs. Both groups increasingly are looking to advanced backlighting sources to deal with these challenges, according to discussions held here yesterday at iSuppli Corp's Flat Information Displays (FID) 2007 conference.
While LCD panels are able to scale down their costs as they get larger, lighting expenses have not declined as have the LCD panels. In fact, lighting costs have increased as a share of total cost in larger televisions.
This is of particular concern to the panel makers, which are absorbing most of the lighting costs. Panel makers also are moving toward using third-party lighting manufacturers to supply them, adding even more cost.
Current LCD-TVs mostly utilize fluorescent light sources that consist of tubes and a series of optical films. On the plus side, these technologies have benefits in terms of life span, high efficiency and high production volume. On the negative side, there are no learning-curve economics for such sources and they contain mercury, which often violates the RoHS requirements. They also have slow start-up times, deliver a poor color gamut and rise in cost as displays get larger.
"LCD-TVs need to improve picture quality in order to convince those consumers still tied to their CRTs or plasma displays," Semenza said. "Lighting is a key aspect to how the LCD-TV market can remove remaining barriers to adoption."
From the cost perspective, as LEDs continue to fall in price, they can begin to provide savings, beginning with the largest screen sizes.
Getting the LED out
While many technologies are available for display lighting, including variations on fluorescent tubes, and emerging technologies such as Field Emission Displays (FEDs) and Organic Light Emitting Diodes (OLEDs), it is the Light Emitting Diodes (LEDs) that stand the best chance of improving LCD-TV backlighting in the short term, according to iSuppli.
LEDs can be used as a direct replacement for standard fluorescent lamps, meaning they are the easiest to implement in terms of design changes and market entry.
Plus, employing time-sequential color in LEDs eliminates the need for color filters. Their capability to accurately control brightness of LEDs enables high dynamic range, a feature just being adopted at the high-end of the LCD TV market.
One problem, however, is that LEDs now are too expensive to be used in the mass market. iSuppli believes there will be significant cost reductions over the next few years, which will position LEDs as a mass market light-source.
The high cost of LEDs will limit their use in LCD-TVs during the near-term. Global shipments of LCD-TVs with LED backlights will rise to 64,000 units by the fourth quarter of 2008, up from 42,000 in the fourth quarter of 2007.
Another emerging trend discussed at FID is the use of advanced light sources in rear-projection TV. Panasonic is using an electrodeless light source in their LCD rear projection sets, and Mitsubishi is developing laser-based DLP rear-projection sets, and plans a private demonstration of this technology at next month's CES conference.
Laser developers are promoting their products as the ultimate evolution of lighting technology.
"LEDs and lamps won't be able to sustain the costs of televisions as products get larger and larger," said Greg Niven, executive vice president of marketing at Novalux Inc., a company developing laser lighting. "With laser lighting the Bill of Materials (BOM) is reduced anywhere from $50 to $200 while offering lower power consumption, thinner panels and brighter, better color," Niven said at FID 2007.
Niven added that laser-based rear-projection sets are close to commercialization, and anticipated the first product introductions in 2008. He also pointed out that front projectors for digital cinema, signage, and highly integrated pocket projectors are also potential applications for laser sources, and even speculated that in the future, LCD TVs could use laser backlighting.