Animated billboards of 1930s

[Axk]

Watching a 1937 film of New York and they have a lot of scrolling text billboards there (these are around 21:00 in this video: https://youtu.be/ZpXnEvW0XD0?t=1265)

I wonder what was the technology behind these? Rear projection?
Trying to google but haven't found anything so far... Need proper keywords.

[rfeecs]

You might look up "news ticker".

There is a famous one in Times Square, since the 1920's:
https://en.wikipedia.org/wiki/One_Times_Square

On November 6, 1928, an electronic news ticker known as the Motograph News Bulletin [fr] (colloquially known as the "zipper") was introduced near the base of the building. The zipper originally consisted of 14,800 light bulbs, with the display controlled by a chain conveyor system inside the building; individual letter elements (a form of movable type) were loaded into frames to spell out news headlines. As the frames moved along the conveyor, the letters themselves triggered electrical contacts which lit the external bulbs (the zipper has since been upgraded to use modern LED technology).

[Axk]

These don't appear to be news, look like commercials (Ford and Chverolet)
I saw that, but these appear to be different.
The Zipper was on a lower floor as far as I understand and the separate bulbs were distinguishable.
These ones are higher up.

[nctnico]

The technology is already discussed in a recent thread.

[Axk]

Do you have a link to that thread?

[ebastler]

https://www.eevblog.com/forum/chat/when-was-the-first-electronic-bitmap-sign-invented/