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


Don't you mean aperture grille tubes.

Yes, I corrected myself in a subsequent post.

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

You are probably right, but when it comes to computer monitors, technology
investment in direct view monitors has probably come to an end with the
advent of flat panel LCD monitors.

I recently wanted a 19-20" direct view Sony monitor to replace my 20" Sony
that died, but could not even find one for sale. They still make a 21 inch
$1800 professional direct view monitor, but that is way too much money (and
too heavy IMO). I ended up with a 19 inch Viewsonic P90f that is very sharp
and cost about $325. It is not exactly the same as the aperture grill, but
is a hybrid technology.