November 27, 2008

FUNAI announces development of "newspaper quality" electronic ink display technology

FUNAI have announced a new technology for ePaper that is causing a bit of a stir and lots of interest. There is excellent coverage of it at the TechOn Japanese web site which I summarize and comment on here (see references below)

Its an electrochromic technology, that is monochrome for now:
Gray scale representation is also possible with pulse width modulation. Although the device supports only four levels of gray scale at the moment, it will be possible to provide higher levels in the future, the company said.
with plans to move to color in the future. It remains to be seen whether via putting a color filter on top of this monochrome technology, or via an inherently color display as hinted at by some of their patents.

They able to do a very fast update (0.1ms) of each pixel.

No TFT Active Matrix is required, it using a line scanning passive matrix addressing scheme. That should make it cheaper, easier to manufacture and easier to move to flexible substrates (for conformability or robustness advantages). Although it seems they need to have a controlled gap in the display which complicates the move to plastic (or at least flexible plastic). They have their sights set on it though:-
The latest prototype was manufactured by using a glass substrate. Spacers are dispersedly located in the device to maintain the gap of 50μm. Another device that employs a plastic film is also under development, the company said. It aims to reduce the price of the latest device to 1/3 of that of the existing LCD panels.
They hint at a multiple pass line-scanning to increase contrast or the dye's optical density.
Because the contrast reaches 100% within 0.1 seconds, the device can smoothly display images on the entire screen just like an active matrix panel. At present, the device scans the screen two to five times before the contrast reaches 100%.
They claim:
A6-sized image within 0.1 seconds when the electrode density is set to 3 pieces/mm.
A6 size being one quarter of A4 or A size or 105mm x 148mmm / 4.13inches x 5.83inches

The reflectivity of the white state is very high at 80%! (remember, monochrome)

The side by side comparison of the display with newspaper, does make the white reflectance, black density and contrast ratio look very good and competitive with newspaper (which is not as white and reflective as standard office/copier paper remember).
The resolution is not so good, but that can maybe be improved.

Their white reflectivity vs. contrast diagram here illustrates very well where it lands compared to print, E-Ink like EPD displays and LCD, although remember that this diagram cannot tell the whole story. Color capability and spatial resolution being at least two other factors when comparing to print, but it's still impressive.

One disadvantage versus competitors such as E-Ink technology is that it is not bi-stable and needs a voltage to retain the image.
In other words, the device requires a voltage to retain an image on the screen, and it is not a bistable ultra-low power device like e-paper.
But the actual power consumed to write and hold the image may make that a non-issue:
The power consumption is 0.16mW/cm2 for writing and 0.08mW/cm2 for holding.
But 0.08mW/cm2 is not a lot!
Doing the maths I make that for an A6 display: 12.4mW for an A6-sized display


No comments: