Japan’s public broadcaster, NHK (Nippon Hoso Kyokai), is making progress on the development of thin, flexible screens that might one day make a roll-up TV possible.
The organization has been working on flexible OLED (organic light-emitting diode) screens for several years and its latest prototype will be on display at an open-day event at its R&D center in Tokyo this week. Reporters were given a preview of the screen on Tuesday.
Compared to a prototype that was displayed two years ago, the most recent one benefits from a more reliable manufacturing process.
As a result, the latest screen has visibly fewer defects and bad pixels than the 2009 prototype.
Like the 2009 screen, the latest is about five inches across the diagonal and has QVGA (320 pixels by 240 pixels) resolution. The images are in colour although the stronger green pixels give the picture an overall green hue.
While the smaller number of imperfections points to progress, their continued presence indicates that researchers still have some way to go before flexible video screens can be commercialized.
The biggest problem is reliably fabricating the pixels and electrical connections so they don’t break when the screen is flexed.
Even when using a firm substrate like glass, there are still some hurdles with OLED technology that prevent commercialization of defect-free large screens, such as the difficulty of evenly spreading the organic electroluminescent material across the surface of the display. While small-size OLED screens are in wide use in products like cell phones, screens of around 10 inches and above are still difficult and expensive to make.
But researchers are sticking with the technology because it can produce a picture that is brighter and more vibrant that an LCD (liquid crystal display) and doesn’t require a power-hungry backlight.
In May 2010, Sony showed a 4.1-inch OLED screen that could be rolled up. The prototype, which is still not a commercial product, had a resolution of 432 by 240 pixels and could be flexed to a greater degree than the NHK display, but also exhibited bad pixels.