computer graphics in the 1950s

Tony Duell ard at
Sat Oct 18 14:55:22 CDT 2008

> On Fri, 17 Oct 2008, Tony Duell wrote:
> > Did anyone try using 3 monochrome CRTs and combining the outputs
> > optically (e.g. by back projectuion)? That would get round the need for a
> > shadowmask
> In the 1970s, there were some projection TVs that had three CRTs.
> Convergence/alignment needed to be adjusted any time the set was moved.

Sure, and actually, thay applies to delta-gun shadowmask CRTs too. You 
had to converge those in the place where the set was going to be used [1]. 

But I was sepcifically asking about a vector displaym biot a raster one. 
A vector display using 3 monochrome CRTs optically combined would not 
have the resolution limit imposed by the shadowmask.

[1] The coming of the in-line gun CRT firstly allowed for portable 
colour TVs, and secondly meant the colour TVs could be sold by what are 
known in the UK as 'box shifters' -- shops with almost no knowledge of 
their products, they just sell you the unit. Before that, a colour TV had 
to be set up in the customers house, something that few people did 


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