this post was submitted on 22 Nov 2023
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Technology

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[–] [email protected] 42 points 1 year ago (2 children)

That looks like a type of Thin film interference, like you’d see on an oil slick or a soap bubble. Wikipedia says:

Thin-film interference is a natural phenomenon in which light waves reflected by the upper and lower boundaries of a thin film interfere with one another, either enhancing or reducing the reflected light.

I’d guess the display uses a thin film on one of its layers causing this rainbow interference pattern that shifts depending on viewing angle.

[–] [email protected] 3 points 1 year ago

like you’d see on an oil slick or a soap bubble.

Or roast beef!

[–] [email protected] 3 points 1 year ago

So if that’s actually just a guess, I’m impressed, and you must have some experience in thin-film lol.

LCD panels actually use a thin film of silicon (I think it’s silicon) over each pixel. And cheap panels using TN technology often have this issue and very poor viewing angles.

[–] [email protected] 17 points 1 year ago

First of all, hi fellow Romanian :)

Second, it might be a TN panel: cheap, but it changes colour a lot at a angle

[–] [email protected] 8 points 1 year ago

Fundamentally, LCD displays like this work by controlling which pixels are dark or light by having polarised light coming from behind (the yellow glow) and then blocking it by switching the polarisation of liquid crystal at a pixel-by-pixel level.

When the liquid crystals are aligned with the light the light gets through to your eyes, when unaligned the light is blocked.

As viewing angle increases, increasing amounts of light leaks though ‘dark’ pixels, because the liquid crystal is no longer effectively blocking it at that angle.

That’s my simplistic understanding

[–] [email protected] 6 points 1 year ago* (last edited 1 year ago) (2 children)

It's a bunch of cheap LCD monitors stringed together, you can see their edges. They tend to have very poor viewing angles, the image starts shifting color hue as soon as you move off-center and it becomes impossible to see as you approach 180° (seen in your pic at the far end). But it doesn't matter in this case because the writing is very large and most people will look at them head on. It's actually a very good use of cheap LCD panels.

[–] [email protected] 6 points 1 year ago (1 children)

I'd say at an 180° angle pretty much every screen is unreadable.

[–] [email protected] 2 points 1 year ago

You'd be wrong, one eye would surely stick out!

[–] [email protected] 3 points 1 year ago

This didn't really answer the question.

[–] [email protected] 5 points 1 year ago

A good explanation of the different thin film transistor (LCD) panel types:

https://tftcentral.co.uk/articles/panel_technologies

[–] [email protected] 2 points 1 year ago (1 children)

@sarmale poor maintenance maybe? Does it look all blue with white text when sitting right in front of it? Or is it yellow-tinted as well? In Brașov I saw the screens looking like that. In Bucharest at the main departure/arrival board (in Gara de Nord) they looked more blue (whether this is due to better maintenance or because they are newer, I don't know).

For any international audience: these screens have become quite common in our train stations in Romania as of late, and they show the train arrivals/departures.

[–] sarmale 2 points 1 year ago (1 children)

In the front they are all blue

[–] [email protected] 1 points 1 year ago

@sarmale then as others said: screen quality maybe 😅

[–] [email protected] 2 points 1 year ago (1 children)
[–] sarmale 3 points 1 year ago

Râmnicu Vâlcea, gară

[–] [email protected] 2 points 1 year ago
[–] [email protected] 1 points 1 year ago

It's obviously magic. Muggles 🙄