The Trinitron patent has
expired, so there are other manufacturers who now make shadow mask tubes.


Don't you mean aperture grille tubes.

And, so far, I only know of at least three manufacturers that make tubes based
on Trinitron, but not totally copying it.

Mitsubishi, NEC, and Viewsonic. But, Sony still makes the best, IMO. No other
CRT uses the LSAGIC electron guns. - Reinhart