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Originally Posted by Yamamaya42
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classic Monty Python.
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Originally Posted by MadMan
Also I don't think Hoffman Easyvision sets were actually green phosphor. Just yellow safety glass.
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I own a late 40s Hoffman (qu)Easy Vision set and can confirm it is a normal P4 phosphor CRT with a separate plate of greenish yellow safety glass in front of it.
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Originally Posted by JohnCT
Sylvania, somewhere about 1980 or so, came out with the Superset. These TVs had a very dark tinted faceplate and had a spectacular picture. These TVs had a beautiful black level. Unfortunately, in order to correct for low brightness, these tubes were driven hard and died early.
Side story: back in the early 70s, my dad used to buy RCA all-new Hi-Lite 23" and 25" tubes for CRT replacements, but also stocked a low end rebuilt tube named "Maverick".
The Mavericks were the economy line and dad used to give customers the option of price. The Maverick's were bright, sharp, and reliable and had excellent purity, but they had the oddest light colored phosphor - sort of a greenish white. I mean, when the TV was off it looked weird. Back then, I couldn't understand why they picture was odd. No matter what I did with the contrast or brightness, I couldn't get a normal picture. Of course, it was the light colored phosphor. It didn't occur to me at that time that the darkest image on the screen couldn't get darker than the unlit light color phosphor.
John
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A decent part of the darkening of 70s color CRTS was black matrix technology. In 1969 or 70 Zenith released the first black matrix "Chromacolor" CRT (within 2-3 years marketing had muddied the meaning of the trade name Chromacolor to make you think it had something to do with the chassis). The black matrix concept was to lay down a grid of black light absorbing material on the inside of the screen such that it would cover the space between the phosphor dots and give multiple benefits....it would absorb room light darkening balcks and improving contrast it also achieved benefits in focus and convergence as well as brightness...the black non light emitting border meant the shadow mask hole guard band could be inverted such that the beam would light the entire surface of each dot. Older tubes had nothing between each phosphor dot so to prevent purity errors (one color gun hitting wrong color phosphor) the shadow mask would block the electron beam such that it only hit and lit the center of the phosphor dot only partially lighting the dot (which would be dimmer than black matrix lighting the entire phosphor dot). Initially the Black Matrix technology was Zenith only but it gradually spread throughout the industry in the 70s.
Some color phosphor mixes (sulfide IIRC) were greenish by formulation, others had a greenish tinted safety glass... Zenith in the early to late 60s painted their screen bezels a light green and often ordered the safety glass tinted the same color to match...It is probable a number of rebuilders used that tint since almost half of TVs were Zeniths (Zenith and RCA evenly split an 85% market share back then).
In the early 60s GE mixed their phosphor so their monochrome CRTs would appear sky blue when powered off...I have a 1962 new car model year issue of look magazine that has a GE add describing this. In the 80s Mitsubishi did this on color TVs too.