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Coming soon to a monitor near you: LEDs

By - Source: Tom's Hardware US | B 0 comment
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El Segundo (CA) - After years of development, the first LCD displays using Light Emitting Diode (LED) backlights are about to enter the market. Initial product offerings will be few and far between, but much of the industry will be watching from the sidelines, gauging the market reaction and weighing the pros and cons of jumping into the game, market research firm iSuppli expects.

LEDs continue to gain traction as monitor backlighting technology, despite the fact that the conventional approach to backlighting -Cold-Cathode Fluorescent Lamps (CCFLs) - has improved dramatically in recent years, achieving higher brightness levels, better uniformity and extended lifetimes.

However, CCFLs have failed to meet the demands of the premium segments of the user community. The needs of these users in the past have been served by high-end CRT monitors that employ an aperture grille tube. Such products serve the small remaining opportunity for premium CRT monitors.

For these users, the issue is color gamut and saturation. CCFLs coupled with the LCDs' color filters cannot compare to the rich color delivered by high-end CRTs using aperture grille tubes and color calibrators.

Many of these users would still be lining up to purchase large- screen CRT monitors utilizing those tubes, but Sony Corp. and Mitsubishi have ceased production of aperture grille tubes, eliminating this option. Thus, these users now are looking to monitor manufacturers to provide them with LCD alternatives that better match their performance requirements.

By using LED backlights in place of CCFLs, manufacturers are able to offer a wider color gamut with richer color saturation. The broader color range and purity is critical to a number of applications including prepress, film editing and production, animation design, computer-aided graphics and select medical applications such as endoscopy. Furthermore, LED backlights are mercury free, a plus for environmentally-sensitive markets such as Europe.

The main suppliers of LEDs for backlights include Lumileds, Agilent, Nichia, Toyota Gosei and Cree.

Monitor makers are banking that users in color-sensitive applications will be willing to pay fairly hefty premiums for these new displays. Designers face a number of manufacturing challenges in producing these units, including:

  • High component costs. The cost of the LEDs used in these backlights has dropped dramatically, coming down from $10 per light a few years ago to less than $5 now. However, that unit cost adds up because displays require anywhere from 40 to hundreds of lights, depending on the size of the screen. Further cost reductions will be needed if these solutions are ever to move beyond niche opportunities.
  • Heat management. LED backlight solutions generate substantially more heat than CCFLs and dissipating that heat poses major challenges for product designers. Fan solutions are problematic, due to noise and cost issues, so monitor makers have spent many hours figuring out how to disperse the heat without them. Lumileds Lighting recently introduced an Ultrahigh-Brightness (UHB) LED that reportedly will work without any heat sinking at temperatures up to 40 degrees Celsius.
  • Light uniformity. Pinpoint lighting solutions such as LEDs can pose uniformity challenges due to the geometry of multiple, separate light sources and from the inconsistency in brightness levels from bulb to bulb. Monitor makers say this problem has been addressed and resolved through the use of specialized light diffusers. CCFLs also use diffusers to spread the light from multiple side-mounted lamps evenly across the back of the panel.
  • Power consumption. Richer colors and superior brightness come at the expense of higher power consumption. However, this is not expected to be a significant deterrent in the early phase of the market. Depending on the unit, power requirements for LEDs can be 50 percent or more greater than similarly-sized CCFLs. Monitor makers are working to close this gap and are confident they will be able to improve power performance over time.
  • Backlight lifetime. Some of the greatest improvements have occurred in this area, where product lifetimes have improved to 80,000 to 100,000 hours, up from 25,000 hours a few years ago.

A number of companies have demonstrated prototypes featuring LED-backlighting solutions. Looking at three of these vendors, we see three very different approaches:

First, NEC Display Solutions of America has demonstrated a 21.3", Ultra-Extended Graphics (UXGA), standard format display featuring NEC's own RGB LED backlight solution. The final system price is yet to be determined.

Second, Samsung has demonstrated a wide-format, 24", WUXGA monitor, featuring its proprietary RGB LED backlight system. While no product has been announced to date, Samsung is expected to bring it to market in 2005. No indications have been given regarding the final system price of such a monitor.

Third, Sunnybrook Technologies, a small startup firm based in Vancouver, Canada, is taking a different approach, utilizing a combination of proprietary software and firmware and an individually modulated LED array of white lights. The combination of the active-matrix LCD and the active-matrix LED al lows the firm to offer 16-bit depth. Sunnybrook's first product to market, a 37", 1,920 by 1,080 LCD display will premier at SIGGRAPH 2005 in late July, with pricing to be announced at that time. Other vendors are expected to follow.

While they deliver great performance, these displays are a long way from meeting that all-important mass-market criteria: competitive cost. However, suppliers are confident that the cost hurdles can be overcome.

The critical question is how quickly costs can be reduced - and no one seems to have a ready answer at present.

Several suppliers believe LCD-based rear-projection TVs are likely to be the first consumer-electronics product to feature LED lighting solutions. However, the technology has tremendous potential for the larger markets of direct-view LCD monitors and televisions - once the cost and technology challenges are resolved. Solutions will take time and effort to implement, but as LCD pioneers have demonstrated already, that's a challenge they are prepared to meet.

Rhoda Alexander is the director of monitor research and has responsibility for Worldwide Monitor Market Tracker, Plasmatrak, and medical display research for the market research firm iSuppli Corp. Contact her at r.alexander@isuppli.com

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