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Old 10-03-2006, 08:03 AM
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Baird query.

If you look on Google, you'll find a site showing picturers of an experimental set built by John Logie Baird in the 1940's (he worked during the war on radar research). Called the telechrome, it combined a radio, automatic record player (phonograph) plus a dual standard television set that could receive the BBC 405 line b & w transmissions and his own experimental 600 line colour. It's well finished with a polished wood case, more like a pre-production model than a prototype. This set was shown to the public but vanished shortly arfter Bairds death; there's a story that RCA got their hands on it. Aparently it was a three colour system (not two) of his own design; there's a photo of it working showing a womans face. Colour's quite good; a bit like early Technicolor. There's not much information about early British colour television; up until the mid 1950's the BBC was the only company (later Corporation) allowed to broadcast either radio or telivision in the UK and Baird had a major falling out with them; he felt that they did not give his first pre-war television system a fair chance. The problem with the BBC is even now, it's run by people with long memories. If in their eyes Baird offended against them, they would not forgive him or give him due credit for his work............ Jim.
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Old 10-03-2006, 05:38 PM
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You may want to check out this recent AK discussion:

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Old 10-03-2006, 07:05 PM
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Early UK Colour.

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.
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Old 10-03-2006, 10:53 PM
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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....
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Old 10-04-2006, 02:27 AM
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Convergence indeed

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.
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Old 10-04-2006, 03:23 AM
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Quote:
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
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Old 10-04-2006, 02:31 PM
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I wonder when the first epiphany on cabinet size vs. front door size occurred and how far along the tube design was. ;>)

["Snodgrass, do you know what width the usual front door is? 36 inches? Whew! It fits!"] Actually, I'd bet they took this into consideration early on due to experience with larger B&W sets.

This was always a consideration for depth of later large-screen rear projection sets.
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Old 10-04-2006, 03:45 PM
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3DTV without glasses?

[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?
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