Platform screens changing from yellow to white LEDs?

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jon0844

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At West Hampstead Thameslink I saw that there's one LED platform departure board that now has white text instead of yellow. It looked very bright.

What's more, it appeared to be exactly the same as the others - so presumably it's just a straight forward swap of the LED panels? That got me thinking that it might be part of a plan to retrofit these to other screens in due course?

I do think these are better than yellow and hope to see them used on more buses too. Especially replacing the older type LED panels where the LEDs faded long before their time (due to crappy components) and so you can barely read the text/numbers unless it's dark.
 
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JaJaWa

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I remember seeing Network Rail trialling a paper version of these at Manchester Piccadilly in November 2014 (see attached) with white and yellow alternating looking particularly clear to me.
 

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HMS Ark Royal

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Looking at that white and yellow demo picture, JaJaWa, makes me think of the old ceefax pages from the TV!

I have to say that although it looks good, and sounds good, I'd rather stick with the orange only displays
 

edwin_m

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St Pancras has some white LED displays too. Also seen them on a few buses recently.

Is there a problem here for people with powerful glasses which may give a prism effect so the different colours making up the white appear to be in different positions?
 

jon0844

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It's a shame we can't use multi colour LEDs so important information can be relayed more effectively.
 

Philip Phlopp

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Why aren't OLED computer monitor/TV screens used?

They're being trialled in a few locations.

Abellio ScotRail has the Blackboxco solution deployed in a few locations, Siemens has their PIS on the new Class 700 under evaluation and there's the KeTech live PIS going into the Hull Trains Class 180 units.
 

Bletchleyite

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Why aren't OLED computer monitor/TV screens used?

They are in places. The problem is that the decision for LED was made when that technology wasn't around - it was plasma (which they tried in Paddington and Waterloo, and it was useless - hard to read and lots of burn-in), LCD (unreliable), LED or physical (flipdot or split-flap).

I think it is probably now time to switch to colour OLED displays, as more flexible information on things like train formation can be added.
 

swt_passenger

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Why aren't OLED computer monitor/TV screens used?

Partly because the stuff they installed last time (which would have been state of the art at that time) still has years to go to see out its expected life. The budget doesn't run to replacing working systems every two or three years as new tech becomes mainstream.
 

Clip

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St Pancras has some white LED displays too. Also seen them on a few buses recently.

Yeah lots of buses if not all in London now have moved over to white on a black background for their blinds. Makes it much easier to see from a distance for sure.
 

edwin_m

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Are OLED noticeably better than LCD screens? The latter are pretty much useless when in direct sunlight, whereas the LED matrix ones can often still be read.
 

jon0844

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OLED has a limited life and the brighter you have them (which is needed for readability in the sun etc), the shorter the life. I'm not convinced they're good for the railway. My phone has an OLED screen and it is great until I'm in the sun.

A home TV is kept for around seven years and that's not always on, plus that's an industry that wants you to replace things, so all the more reason it's probably not great for platform screens.

Doesn't surprise me companies might try them and then invest in something that proves very costly over time!

I could see then being used for advertising boards though. Advertisers paying to have them replaced as and when required.
 

Camden

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Seems strange to me that no one has gone with backlit e-ink, like Kindles have.

They only draw power when changing, and for the backlighting (which can obviously be as cheap as modern ordinary lighting technology allows).
 
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Seems strange to me that no one has gone with backlit e-ink, like Kindles have.

They only draw power when changing, and for the backlighting (which can obviously be as cheap as modern ordinary lighting technology allows).

Can e-ink screens be built in such a large format? I've never seen them used for anything larger than a Kindle.
 

HSTEd

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Nothing beats the glory of split flap displays.
And the amazing noise they make when they change - noone could complain they missed important updates.
 

jon0844

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Can e-ink screens be built in such a large format? I've never seen them used for anything larger than a Kindle.

Multiple panels could work to replaced printed timetables. I've seen the TfL bus stop trial and they're okay, but didn't seem quite as easy to read at a distance as I expected.

Another issue might be if the power fails, or the connectivity fails, and the screen sits showing totally wrong info for ages.
 
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nidave

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nidave

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That's quite impressive... I wonder whether they're really bright enough for platform screens, but 32" is probably big enough! I had no idea.

There is still an issue with refreshing as you have to draw the negative to reverse the charge. The more colour pigments there are the more refreshes it needs - its more obvious in the 2nd video. that rules out any scrolling as there are ways to refresh part of the screen but you get "ghosting" - Not sure if that will ever be overcome or if its a case of working round it.
 

jon0844

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There is still an issue with refreshing as you have to draw the negative to reverse the charge. The more colour pigments there are the more refreshes it needs - its more obvious in the 2nd video. that rules out any scrolling as there are ways to refresh part of the screen but you get "ghosting" - Not sure if that will ever be overcome or if its a case of working round it.
Ideal for posters showing engineering work, emergency timetables and info that doesn't require changing often - but allows info to be relayed quicker than printing new posters.

The cost clearly needs to come down though!
 

Via Bank

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Can e-ink screens be built in such a large format? I've never seen them used for anything larger than a Kindle.

There is (or was) at least one London double decker running around with an e-ink blind on the front on route 16 last year. So I can't envisage there being a problem with PIS screens.
 
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