Sony Corp developed a 13.3-inch flexible color electronic paper (e-paper) device and announced it at the 49th SID International Symposium, Seminar & Exhibition (SID 2011), the world's largest academic conference on display technologies.
After making the announcement, the company exhibited the e-paper device in the author's interview, gathering a large crowd of people. And many researchers highly evaluated the image quality of the device.
This time, Sony realized a thickness of 150μm or less and a weight of 20g or less by using a plastic substrate. The e-paper device has a 13% color gamut on NTSC standards, a reflectance of 10% and a contrast ratio higher than 100,000:1.
Its pixel consists of red, green, blue and white sub-pixels, and the sub-pixel count is 1,600 x 1,200. The sub-pixel measures 169μm x 169μm. The resolution and gradation of the screen are 75ppi and 16, respectively.
The high color gamut and reflectance were achieved partly because it became possible to attach a TFT substrate to a color filter with high precision (5亮m), Sony said. Because of the high precision, the company succeeded in reducing the margin between sub-pixels and increasing the aperture ratio of pixels to ensure the high color gamut and reflectance.
To ensure a high enough aperture ratio, Sony used a glass substrate that can be easily handled even with existing manufacturing equipment as a substrate for supporting purpose.
The e-paper device is manufactured as follows. Adhesive is applied to the glass substrate, and a plastic substrate is attached to it. Then, amorphous TFTs are formed on it with a low-temperature process (180°C or lower). Lastly, the plastic substrate is removed from the glass substrate.
Correction Notice: Because of a reporting error, we made the following corrections.
4th paragraph: the pixel count is 800 x 1,200 (wrong) - the sub-pixel count is 1,600 x 1,200 (right)
5th paragraph: it became possible to attach a TFT substrate to E Ink Corp's front plate with high precision (0.35亮m) (wrong) - it became possible to attach a TFT substrate to a color filter with high precision (5亮m) (right)
6th paragraph: To enhance the precision in combining the TFT substrate and the front plate (wrong) – To ensure a high enough aperture ratio (right)