Japan’s NHK Betters Sony With 5.8-inch Flexible OLED

Researchers at Japan’s public broadcaster, NHK (Nippon Hoso Kyokai), have developed a flexible OLED (organic LED) display that’s 5.8-inches in size and can display moving images in color.

The screen is seen as a potential base for a lightweight, portable television that could be unrolled to enjoy video programs almost anywhere although a lot of work needs to be done before that dream can be realized.

The sample displayed by NHK showed moving images well but, indicative of the early stage of development and prototyping, had many bad pixels and lines that were stuck on one color. Part of the problem is that connections are vulnerable to breaking because of the flexible nature of the screen, which differs from conventional displays that are made on sheets of rigid glass.

Similar imperfections — although less of them — were visible in a flexible OLED developed by Sony that was on show at this year’s Consumer Electronics Show in Las Vegas. The Sony screen was smaller at 2.5-inches in size and had a slightly lower resolution of 160 pixels by 120 pixels compared to the NHK screen, which had a resolution of 213 pixels by 120 pixels.

NHK’s screen is darker than Sony’s prototype and improving the brightness and contrast are two of the main jobs ahead for developers. They also want to increase to size to that of an A4 sheet of paper, which is about the same as a 14-inch display.

The screen was on show at NHK’s Science & Technical Research Laboratories, which is developing the technology and looking for partners among electronics companies.

OLED screens have pixels that contain an organic material that emits its own light so no backlight is needed. That helps make the displays thinner and reduces power consumption. OLED screens also handle fast-moving images better and offer richer color reproduction than current LCDs and PDPs (plasma display panels), but they remain difficult and expensive to produce.

While OLED screens have started to appear in mass-market portable gadgets such as music players and cell phones they remain rare at larger sizes. Only one OLED television has been put on sale. Sony’s XEL-1, which features a 11-inch OLED screen, hit the market in December 2007 and its price has remained stuck at a relatively expensive ¥200,000 ever since.

Sony and several other major consumer electronics companies have showed prototype screens at larger sizes but they are yet to go on sale.