Electronic Design

OLED TVs Get Ready To Hit The Japanese Market

Major players in the electronics market have long been exploring ways to turn organic LED (OLED) displays into a potential successor to LCD screens for TVs. Last month, Sony became the first company to announce plans to start selling the ultrathin TVs in Japan within the year.

The company's 11- and 27-in. OLED TV displays were a hit at the January Consumer Electronics Show in Las Vegas and at a recent display forum in Tokyo, where participants were drawn to the 3-mm thick screens, high-resolution images, and wide-angle views (see the figure).

Smaller electronic devices, like cell phones and digital cameras, already use OLEDs in their displays since the technology consumes less power and allows for thinner panels. Unlike LCD screens, which require a fluorescent backlighting source, OLEDs use electrophosphorescent materials that glow when an electric current passes through them.

Here's how it works. When voltage is applied to a thin, organic polymer film placed between two electrodes, the semiconductor emits patterns of light and color. Each individual pixel can be controlled for these patterns, which, when combined, form a sharp, crisp picture.

One challenge for Sony, which began its OLED display research in 1998, was in creating displays large enough for watching TV, said company spokesperson Mina Naito. Other companies such as Samsung, which has developed a 40-in. OLED TV not currently on the market, have been working with amorphous silicon (a-Si) technology to increase display size.

A-Si supports larger substrate sizes than polysilicon, the standard substrate used in OLED displays. And since a-Si is a mature technology used in most LCDs on the market today, it could pave the way to mass-production for OLED TVs. For the 11-in. displays going to market, however, Naito said Sony will use polysilicon technology because it generally "has a higher electric carrier mobility than amorphous silicon."

Another challenge, Naito said, is the lifespan of the display. The blue LEDs, which typically fail after 3000 to 5000 hours, are largely to blame. While red and green LEDs last about 10,000 to 40,000 hours, the entire screen's lifetime is limited by that of the blue LEDs.

Due to these cost and production hurdles, Sony has not yet released information on unit targets or pricing for the OLED TVs. The company also said it is only considering the possibility of introducing the TVs in markets outside of Japan at this point.

Sony isn't the only company with a vested interest in OLED TVs. Seiko Epson, Canon, and Toshiba have announced plans to develop the technology. Before Samsung announced its 40in. a-Si OLED TV in May 2005, it had developed a 21-in. display in January of that year. But the company has not yet taken these products to market.

As with any technology, given demand and time, quirks and hurdles will be easier to overcome. Yet it remains to be seen whether the OLED TV sales will transform into the multibillion-dollar market some analysts expect it to become.

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