Liquid Crystal Displays Light the Way

NASA Tech Briefs, Jan 2005

Evident in PTB's discussions with industry experts was the dominance of liquid crystal display (LCD) technology across a majority of today's application areas, with few, yet noteworthy, exceptions. Despite its current stature, LCDs will face increasing competition as newer technologies evolve into viable alternatives.

At the forefront are the advancements in organic light-emitting diode (OLED) technology. Because they require no backlight, OLED displays are said to be lighter, thinner, and may one day be simpler to construct. These displays also offer a wide viewing angle (even in bright light) and operate with low voltage.

"Organic LED seems to be the next latest and greatest technology. It looks very interesting long-term, maybe five years depending on the marketplace," stated John Peterson, president of Endicott Research Group, a supplier of standard and custom DC-AC inverters for backlit LCDs. Peterson explained that OLED is not the kind of technology that you can just make in any size. There is still some question as to how adept it is at addressing the power requirements and power shifting for larger displays.

Sriram Peruvemba, general manager of Flat Panel Display Systems for ThreeFive Systems, added, "Current limitations include image retention, differential aging (blue ages faster than red and green), short lifetimes, and high cost due to the low volumes being produced. As these problems are conquered, OLEDs will indeed become a viable mainstream technology."

Taking a closer look, active and passive OLED displays are not following the same timeline. Despite the fact that passive OLED displays have already started making their way into products like mobile phones and PDAs (mostly as sub-displays under 1.5"), Johan van de Ven, chief technology officer of Philips Mobile Display Systems, does not expect active OLED displays to reach significant volumes until 2007 or 2008, even though the majority of technical limitations will be solved by 2006 or 2007.

In order to produce larger-sized (main screen) OLED displays with higher resolution, active-matrix (thin film transistor or TFT) driving is necessary. Applications will initially range from mobile phones to notebook computers and PC monitors. "The future of OLED is really active-matrix," said van de Ven. "Active-matrix OLEDs will be available in multimedia and high-end products in serious market shares by 2008 or 2009. In five years, large panel screens may even employ OLEDs on a niche basis, but they will not really be available throughout the market for another 10 years."

Jos Klippert, marketing director of LCD TV Solutions for Philips Semiconductors, cautioned, "There will be emerging technologies such as OLED; however, they will have to compete against massive market acceptance of LCD and the economies of scale of the installed base."

Noting the company's interest in emerging technologies, Ian Matthew, 3D business development manager for Sharp Systems of America, indicated that they plan to add more realism by creating "glasses-free" 3D display technology within the LCD, which will be controlled by the software or TV program, depending on whether it is for a monitor or television. "Of course, the display is not the only part of this. Content providers and networks have to come on board to make this happen. We don't see this becoming common in televisions for some time," said Matthew, adding that HDTV is, however, a good example of how fast new technology can be accepted.

In Charge & Large?

"The dominant technology across the board today is LCD, yet we do still see cathode ray tubes (CRTs) used in the TV industry and to some extent in the desktop monitor industry," said Steve Vrablik, director of Business Development for Toshiba America Electronic Components. "CRTs are really only in the larger size TV applications at the moment. For the most part, LCDs have pretty well taken over industrial, consumer goods, and automotive markets."

Even though plasma display panels (PDPs) abound in today's large-format applications, LCDs are expected to encroach on and eventually capture this space, too. "LCDs will continue to dominate the large-screen markets, displacing PDPs in the 40"-70" markets," stated Matthew.

Advancements in enabling technology are expected to improve LCD performance and help create this shift. Lightemitting diodes (LEDs), for instance, are an increasingly attractive light source option. "We have already helped enable LED manufacturers to capture more markets that they may not have otherwise been able to by providing them with a technology that enables them to more efficiently use their products," said David DeAgazio, director of sales worldwide for Global Lighting Technologies, a provider of MicroLens(TM) white LED-based solutions for LCD backlighting. "Manufacturers are looking at using LED backlighting in technologies ranging from small mobile phones to large widescreen TVs."

DeAgazio continued, "Current lighting systems for LCD televisions look like a toaster oven with rows and rows of fluorescent lamps behind the display to provide enough light. The problem is that you don't get your full color spectrum. With LED backlights, you're going to get truer color tones, similar to those of a plasma TV display."