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E-paper Forum » General Discussion » Philips colour epaper cemonstrator
Philips colour epaper cemonstrator
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Posted 1 year ago #
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I'd like to see practical implementation of this. If they can do this without color filters, this would be amazing - they would achieve much better saturation/brightness.
Posted 1 year ago # -
I think practical use of this is the real test - there are problems with stacked pixels too as they are very hard to "get right". I think there might still be more mileage in filters, but only if a better white is found. At the moment although the filters do sap all the light coming in, if the reflection from the white state behind the filter is improved, it could be a more viable route. The current E-Ink white state looks quite grey - I don't have the figures, but I expect it is not fantastic in the current films, but if they can find a way to boost that then filters could come back into fashion.....not that they ever really went out of fashion.....you know what I mean! ;)
Posted 1 year ago # -
"the current E-Ink white state looks quite grey"
Can you explain why this is? How can E Ink improve it so that it has a bright white appearance?
What is the reflectance of Ink of Paper? 100%? The May 2009 Issue of Nature Photonics says they can achieve >85% white state reflectance with their Electrofluidic technology.
Posted 1 year ago # -
E Ink's Vizplex display has 40% reflectance.
Posted 1 year ago # -
I'm not 100% sure why their white looks so grey to be honest. What would improve it would be increased pigment content in the microcapsules and increased capsule packing density. If all the capsules are spheres of exactly the same size there is a limit to how closely they can pack. I don't know exactly what this is in terms os surface area, but if you think of it in terms of volumes, they can only pack to 78% by volume so there is some "dead" space there. I'm sure somewhere on the net there is a page which tells you what surface area can be covered by close packed spheres. Anyway, either way this packing limit will reduce the density of the white or black.
I'm not 100% sure on the make-up of the sheets they sell either but there are a couple of ways that you can lose density there too. One is from the covering top electrode/polymer (I assume polymer as it is flexible I think) which is the outer surface we can touch. There must be some sort of adhesive used which could reduce optical density. The final way (of the ones I thought of anyway!) is from the microcapsules themselves which will again be polymeric but exactly what they are I don't know.
I don't know what the reflectance of paper is as a comparison. What is normally quoted is the contrast ratio - the difference between the black and white. E-Ink claim that their films have almost the same ratio as paper which I can beleive. This is ok for monochrome images but then if you want to transfer to using colour filters you need to improve that reflectance drastically and instead of comparing to your black state you need to compare it to the full range which is possible ie somewhere on the scale from 0-100% in absolute values.
Generally though, to increase the density you need more pigment over a higher area with less interference from other materials you have in there! I've thought of a few things which will affect it, but I bet there are dozens I have missed out!
Posted 1 year ago #
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