Developers say a bright large-size full-color OLED (organic light-emitting diode) display is still some way away from commercialization, but in some areas, OLED displays -- also called OELDs (organic electroluminescent displays) -- are already replacing LCDs (liquid crystal displays). At Ceatec Japan, which opened on Tuesday at Makuhari Messe in Chiba, some vendors showed what current OLED technologies are capable of.
OLED displays use organic compounds that emit light when exposed to an electric current. They are brighter and have better contrast with wider viewing angles than LCDs. Since OLEDs can eliminate the need for the backlight required by LCDs, their panels can be made thinner. This feature is expected to be adapted to applications like flat-panel televisions.
Sanyo Electric Co. Ltd, one of the leading OLED developers, believes full-color OLEDs will become the mainstream display technology in the future, said Kiichi Hirano, chief planner of OLED Display Project at Sanyo.
The company unveiled a 15-inch (37.5-centimeter) 260,000-color active matrix OLED television prototype at Ceatec, although its commercialization is still not expected for at least another two to three years.
The biggest hurdle is the short lifespan of OLED displays. They are suitable for use in mobile phones but do not yet have the lifespan expected for home appliances like televisions, which tend to be in near-constant use.
Although OLEDs do not require a power consuming backlight, OLEDs still consume around the same power or slightly less than LCDs with the backlight, said Kiyoshi Matsuda, sales and marketing manager of OEL (Organic Electroluminescent) Division at Tohoku Pioneer Corp.
Sanyo plans to mass produce 2.2-inch and 2.16-inch full-color OLEDs for mobile phones for the Japanese market this year, because they have faster response times which makes video playback clearer, and are thus suitable for 3G (third-generation) phones.
On the other hand, the area-color OLED displays, which can display five colors, have a simpler structure and the technology is more mature than the active-matrix type, so that they have already been commercialized. Tohoku Pioneer, the leading company in passive-matrix OLEDs, have put single color or passive-matrix area-color OLED displays in devices such as clamshell-type cell phones, for the small window display at the back, as well as in car stereos and DVD players, which used to have monochrome LCDs.
"Passive-matrix (area-color) OLEDs are for applications that do not require a full-color display," said Hiroshi Maehara, sales and marketing manager of Tohoku Pioneer. "Look at this contrast and wide viewing angles and compare them with the existing monochrome LCDs used for things like DVD player display windows. There are still many such applications which use monochrome displays in the market."
The company has developed 10 different area-color displays since 1999 and suggests OLEDs could be also used for interior signs in airplanes, on refrigerators, wrist watches, MD (MiniDisc) players, and wearable safety signs attached to vests or helmets.
Ceatec Japan will continue until Friday.