Quote:
Originally Posted by Electronic M
...The black matrix ... multiple benefits...Initially the Black Matrix technology was Zenith only but it gradually spread throughout the industry in the 70s....
|
Another advantage of "negative guard band" (illuminating the whole dot) was the total elimination of white field purity problems. In the old tubes, even if the individual red, green, and blue fields were pure, errors in beam landing meant the beam could land on a more or less efficient part of the phosphor dot. If this was different for each primary color, the resulting white would be slightly off-color in some part of the screen. The 21AXP22 in my CTC-5 shows this problem.
Zenith had to go to court to defend its advertising of the advantages of black matrix tubes - they were sued by other manufacturers claiming that Zenith's statements were unfounded, but Zenith prevailed.
Much later, RCA introduced tinted phosphors. Each color of phosphor was tinted its own primary color so that reflection of the other colors was reduced. When you examined the face with a magnifier and the set off, you could see that each dot (or line, for in-line tubes) was tinted.