[abstractbeliefs]

I don't think that's quite how it worked.

The colour was created by different phosphors on the inside of the screen, there was nothing different about the electron beams. The number and pitch, the resolution, of these different phosphor dots determined the resolution of the screen.

The shadow masking was to prevent the beam for, say, the red phosphors sweeping blue/green subpixels when moving from one pixel to another, since it wasn't practical to turn the beam off and then back on once the steering coils had been changed. Steering was continuous, so without shadowmasks, you would illuminate on the neighbour subpixels you pass on the way.

You could have done it all with a single beam, if you really wanted, but it's not very practical - you'd need to sweep slower since you could only illuminate 1 subpixel at a time, it'd take much longer to to steer, illuminate at the right level, and move to the next with the right beam power selected.

[mlyle]

> I don't think that's quite how it worked.

I think he described exactly what you did (in fewer words) in the second half of his post. ("Your typical color TV ..."

The first half discusses that some projection screens had 3 different tubes. ("Very few broadcast TVs ...")

Either that or he edited his post.

[abstractbeliefs]

My objection is:

> Your typical color TV effectively created "pixels" by their use of shadow masks and three separate beams.

It's true that almost all colour TVs are pixelated and have shadow masks and three separate beams, but it's got the cause and consequence the wrong way around.

The pixels are created by the phosphor dots, not the mask/tube design. It's possible to use this design without three tubes or the screen, strictly, but a consequence of this design suggests the optional addition of a shadow mask and additional tubes as a natural, later progression for improved performance.

[mlyle]

> It's possible to use this design without three tubes or the screen, strictly,

Without shadow masks or an aperture grille seems pretty dang hard. Even ignoring the alignment concerns, it requires a much, much higher bandwidth.

The shadow mask and aperture grille approaches were the only approaches that ever really worked for color CRTs.

Phosphors and some kind of masking is how you make different colors on a single tube. Indeed, the shadow mask or aperture grille was offset 3 times and used to etch for the phosphor coatings in most manufacturing processes.

> l addition of a shadow mask and additional tubes as a natural, later progression for improved performance.

There's just one tube-- multiple guns/beams, though.