Color CRTs, dot pitch, resolution and the like...

Hey all,

Time to play: check my math (and theory)...

I was pondering the VGA/SVGA Vision Pro monitors that Happ sells (they're on
sale now, BTW-- $200 a whack if anyone wanted one to experiment with).

The "dot pitch" is advertised as 0.78mm. According to Google, that makes
for about 0.030708 inches.

If we assume a full 19" of the CRT is visible area (not likely) and the
aspect ratio is 4:3, that would make for a display area about 15.25" x 11.5"

So if the 'dot pitch' was arranged as a rectangular grid of 0.030" blocks...
15.25 / 0.030 = ~508 pixels. Since the dot pitch is a diagonal measurement
and since the triads are arranged in a sorta tessellated pattern, I'd
guestimate that the 'effective' resolution would be about double-- so around
~1000 pixels horizontal?

(That kinda passes the sniff test since the tube is spec'd for 800x600 pixel
resolution and with a smaller actual visible area than this example you'd
probably be guaranteed to hit a couple triads with even the smallest pixel @
800x600 with standard sync/clock rates.)

This sound about right to anyone else? (I was just thinking that even if
using one of these 'high res' "SVGA" tubes, the active area of the CRT could
be resolved with 10 bits of DAC in a vector output stage if you don't need
overscan. You'd not see any loss of 'resolution' since the dot pitch of the
monitor is the limiting factor...)

-Clay

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Received on Thu Apr 19 02:39:04 2007