Quote:
Originally Posted by Carmine
As was mentioned earlier, the extra difficulties with convergence and pincushion presented by a rectangular tube were the reasons the first color sets were round, not an inability to blow a rectangular glass funnel.
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I think a rectangular screen's surface is "spherical" just like a round screen's one... the only real difference is the shape... early rectangulars also had more or less the same curvature radius as roundies...
actually, one could say that a 21 inch rectangular screen is just a cut out section of a larger 21 inch round screen
i don't think the difficulty into making a rectangular screen is a matter of pincushion corrections, it's more likely a matter of easier shadowmask and phosphor dot screen construction...
The real challenge with pincushion correction and convergence came out with 110 degree color CRTs, earlier 90 or 70 degree tubes were much easier to drive... and for this very reason many late cheap sets are going back to 90 degree CRTs...