Please help me identify this interesting display

Hello,

I can't see clearly in the picture whether the segments are just painted plastic blocks or actually LEDs.

I'd personally write to that technician one more time and specifically ask about the supplier (that probably won't be a secret). There are many companies that specialize in these displays and there are many types (mechanical, LED matrix, LCDs...). Most of these displays are custom manufactured for a specific purpose. Each transportation company has it's own idea of what the perfect display should like

David

If I had to guess I would say it is a split-flap display which is a variation on a flip-dot display pioneered by Ferranti or Ferranti-Packard.

Electro-mechanical pixels with a fluorescent side and a black side that get flipped by electro-magnets.

The segmentation is too intricate for a flip dot. (Those characters are only a couple of inches high.)

I'd say it's LCD. I can vaguely remember a job which included a couple of similar displays back in the mid 1990s. I think the ones we worked with were made by Siemens. The backlight was a tube running along behind each row of characters. The individual characters sat on an internal multidrop bus (RS422, or RS485, or something like that), so it was simple and neat inside. There was an interface board at the end which didn't have to do much other than relay the data on to the characters. At the time, Siemens was a hugh company with their own semiconductor division, so they would have been making the LCDs and semiconductors themselves. These units sold for a considerable premium above the kind of LED signage that we were making but would have cost them much less to build, so they would have been making a tidy profit on them. I don't know what my role would have been - I probably just looked at the stuff being sent to the display with a scope to give the programmers a helping hand with getting the interface to the thing working, or something like that.

It looks really similar (but yellow instead of green) to the UK trains message signs on Network Rail up till about 5-10 years ago (they have changed them since then) and they too looked like LCD. So my guess for the one in the photo is LCD too.

They look like they could be 111 segment LCD displays.

Similar to REITBERGER Alphanumeric LCD large displas or LCD - Segment Displays

I think I found it. Check this out: Ateg - Automation GmbH (I'll put the image below too)

Looks as though you were correct and it is indeed an LCD!