story
Edit: if anybody knows otherwise, show me some evidence, don't just downvote. If these things are widely used, why are they impossible to find by searching? Why doesn't this electronics site know about them:
https://www.eeeguide.com/?s=cooperator
Why aren't they in any books when I did a full-text search on archive.org? Why doesn't Wikipedia know about them? Why aren't there threads about them on electronics forums?
I found them (through an image search) in exactly one place: educational training boards made in India by Jainco, like this one:
https://jaincolab.in/delta-modulation-and-demodulation
But this other one talks about a "ramp comparator" and then repeats the phrase but using "ramp cooperator" instead.
https://www.jaincolab.com/firing-circuit-using-ramp-comparat...
So I surmise it's an error and not a real thing.