Japan Display develops paper-like, video-playing reflective LCD
By Darren Quick
November 5, 2012
Anyone who has tried to view the display on their tablet or smartphone in direct sunlight (which I’m guessing is pretty much everyone) will know that outdoors isn’t the ideal viewing environment for LCDs. E-Ink displays, such as those found in the Kindle, rely on reflected light rather than backlights, which is why they're better suited to outdoor viewing. Now Japan Display has created a paper-like, low-power, LCD panel that relies on reflected light and can display color video.
Japan Display, a merger of Sony, Hitachi and Toshiba’s small and medium size LCD panel businesses formed in conjunction with the Innovation Network Corporation of Japan (INCJ), developed the new display technology with a reflective electrode replacing the backlight found in conventional LCDs.
A liquid crystal layer is sandwiched between the rear reflective layer and the top "Light Control Layer." Light reflected from the rear electrode passes through the liquid crystal layer, which produces a monochrome image, before color filters in the top Light Control Layer add color. The end result is a color LCD panel with a paper-like quality.
The company has developed two versions of the display, both of which measure 7.03 inches diagonally. Because the Light Control Layer collects some light, the reflection rate is not 100 percent. The first version has a reflection rate of 40 percent and is able to produce five percent coverage of the NTSC color gamut, while the second boasts a higher color purity with the ability to cover 36 percent of the NTSC color gamut.
The trade off is that the refection rate of the second version is 28 percent, which means it produces a slightly dimmer image. The second version is also a slightly lower resolution at 576 x 1024 pixels, while the first version packs 768 x 1024 pixels. Both have a contrast ration of 30:1.
Another advantage of the technology is its low power consumption when displaying still images. Because the electronic circuits controlling the pixels can retain data once it has been written, power consumption is kept to just 3 mW when showing static images.
Japan Display’s Kazunori Yamaguchi says that while the high color gamut display still has some issues that need ironing out, the other display is ready to go into mass production now.
Japan Display demonstrated its new screens at the FPD International 2012 exhibition in Japan last week. DigInfo's video from the exhibition can be seen below.