Baird query.

[Steve D.]

You may want to check out this recent AK discussion:

AudioKarma.org Discussion Forums - British Color Experiments - 1950s mystery photos
Address:http://www.audiokarma.org/forums//sh...ad.php?t=76927

-Steve D.

[Combwork]

Thanks Steve,

It's pretty well established now that the BBC did give limited colour cover of the Coronation in 1953, `though people still disagree as to whether it was by landline or short range broadcast, or come to that whether it was Field Sequential or early NTSC. The BBC don't seem to have any records of it, or none that they'll admit to. I wish I knew more about this, but I've read a description of an early colour television by Baird in which three electron guns were mounted seperately; two behind a translucent screen which was ridged at the back and flat at the front. and one in front, set at an angle and firing back towards the screen. One side of each ridge at the back would be coated with one colour phosphor, the other side with a different colour phospher and the flat front with the third colour. From memory, this screen was set across the middle of the tube. Viewed from the front, the picture would appear to be in the middle of the set rather than at the front........ Jim.

[Carmine]

That would be some convergence set-up huh? Requiring three yokes, or was it electrostatic?

And you thought 21" consoles were heavy & huge?

Something to also consider... I have heard that screens never got bigger than 21" because a larger 70 degree CRT would require a tube wider than the typical American entry door (back doors are 32", fronts are 36"). Just some food for thought....

[Combwork]

Hi Carmine,

Convergence would indeed have been interesting but this settup (which I've only read about `third party'; I've no other knowledge of it) raises an interesting thought. One thing that has always been claimed about Baird was that he was interested in television with depth. Not the kind of holographic settup that could conceivably put an image in the middle of a room; more like a cross between looking out of a window and the kind of 3 D postcards that rely on a ribbed coating on the picture. Just suppose a picture tube was made using two b & W images from seperate electron guns firing onto the back of this ribbed screen. Would this give a picture not too unlike what you see out of your window? While we're imagining things, what would happen if a field sequential type colour wheel was set in front of it? ............. Jim.

[cbenham]

[QUOTE=Combwork]... "Just suppose a picture tube was made using two b & W images from seperate electron guns firing onto the back of this ribbed screen. Would this give a picture not too unlike what you see out of your window?"

I saw a 3D demo and the NAB convention about 1992 or so that worked exactly this way. A direct view CRT. 3D without wearing polarizing glasses. It was in color too.
It looked OK near the middle of the screen, but not out near the edges. Paralyx problem?

[blue_lateral]

Originally Posted by Carmine

Something to also consider... I have heard that screens never got bigger than 21" because a larger 70 degree CRT would require a tube wider than the typical American entry door (back doors are 32", fronts are 36"). Just some food for thought....

Hmmm... I never thought of that, even though I have fought plenty of 21" consoles through American front doors. I always used to think it was because 25" is where the picture degrades to the point where making it bigger makes it look worse, due to the scan lines, and lack of resolution. 21" round is about the same image size as 25".

I think you probably nailed the real reason.

John