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View Full Version : Contrast looks best at 170 degrees angle?


CommanderROR
08-12-2006, 05:45 AM
I made a strange observation with my Iliad:

If I put it on a table and look at it froma n angle of nearly 180 degrees, the background is very white and the text is very black. This position would then be an optimal reading position, but of course you can't really read very well from that angle.

My idea is, that the improvement in contrast is due to a "thicker" layer of "display particles" between the eye and the backplate. If this is correct, then maybe a thicker eink display could display better than the current ones? Or is it the particle density?

Does anyone else notice this? i've been wondering about if for a while now and finally decided to ask the community about it...let me know what you think.

ath
08-12-2006, 07:38 AM
If I put it on a table and look at it froma n angle of nearly 180 degrees, the background is very white and the text is very black. This position would then be an optimal reading position, but of course you can't really read very well from that angle.

180 degrees from where? Incident light?

CommanderROR
08-12-2006, 10:18 AM
170 degrees in relation to my line of sight...put it flat on a table and sit on a low chair...then you have it.

arivero
08-12-2006, 11:00 AM
Brewster angle.

ath
08-12-2006, 11:22 AM
170 degrees in relation to my line of sight...

Uh ... ? You look at it at 170 degrees angle from your line of sight? (The mind boggles ...)

put it flat on a table and sit on a low chair...then you have it.

That means something like 80 degrees from the normal, the 'straight on line,' of the screen. (170 degrees would be looking at it from below ... ) Perhaps I'm too literal-minded ...

Anyway, I see no difference between straight on, and sideways, myself. Could depend on the light source ... but doesn't seem so: I've tried daylight, fluorescent light and incandescent light -- I see no clear difference.
But of course that can't show up on the poll ...
(I evaluate the 'white' of my screen to approximately 65-70, if 0 = pure paper white, and 100 = ink black. That doesn't seem altogether good ...)

arivero
08-12-2006, 01:36 PM
From the wikipedia, the Brewster angle is expected to be about 56 degrees off from the perpendicular. But it is not glass but plastic, and they are using some anti-reflection trick (or they should).

CommanderROR
08-12-2006, 02:06 PM
you are right about the angles...I "calculated" my angle a bit incorrectly...

actually it's close to 90 degrees from normal...almost parallel from you "eye-line"

ist that clearer? I've never been good with angles...:-)

ElaHuguet
08-12-2006, 02:49 PM
I agree with you, Commander, I think there's a BIG difference depending on light, flourescent makes it look a lot whiter (so does sunlight), and angle; in the kitchen, I left it on the counter and sat on a stool, and also noticed how good it looked. :)

CommanderROR
08-12-2006, 04:14 PM
thanks Ela...^^

Finally somebody shares my belief...:-)

yokos
08-14-2006, 06:10 AM
@ CommanderROR: I can't answer your poll, because my answer is not chooseable - i see no difference in contrast.

I tried very hard but I can't find any difference in contrast if I change watching angle. test setting: daylight on cloudy day.

donkaarlos
08-14-2006, 12:39 PM
Hi,
I would think that part of the reason that contrast is higher, when looking from an angle is simply that "printed area dot density" increases, while in "unprinted" areas there are "no dots" that could look denser from an angle. The smooth surface and the slight gloss of the screen might increase the effect.

With printed samples similar effect can be seen. Try it your self or look at the enclosed picture. With the e-ink structure the effect might be stronger as the colour particals actually form a "3D dot" bellow the screen surface, instead of the 2D print surface. From sideview you might see the surface and a hint of the dot depth? :uhoh:

donkaarlos
08-14-2006, 02:07 PM
My idea is, that the improvement in contrast is due to a "thicker" layer of "display particles" between the eye and the backplate. If this is correct, then maybe a thicker eink display could display better than the current ones? Or is it the particle density?


My guess would be anyway, that increasing thickness wouldn't help ... increasing partical color contrast and partical density bellow the screen surface would help. With a given partical size and density one should be able to calculate, what is the layer thickness that can be seen from top. Increasing layer thickness beyond that would not help. One would guess that they have done a great deal of contrast and density optimisation work, when developing the display?

El Chupacabra
08-28-2006, 05:48 AM
I noticed that while it was next to me on the table and I was uploading documents from the computer. It has an astonishing contrast.

pdam
09-21-2006, 10:06 AM
Obviously at 170 degrees - mainly so you can say to the jealous person on the train next to you - "look you can still view it at an angle of 170 degrees - cool or what!"