I was born in ’99, so I grew up in the last age of CRT TVs. I’m wondering why they were built to have curved screens. It’s not like flat screens weren’t a thing, because films were projected onto flat screens in movie theaters until IMAX became a thing. But I wonder what about cathode rays made curved screens a necessity until plasma, LCD, and LED televisions came about.
In: Technology
There was a combination of factors. First, spheres are stronger against implosion. A totally flat screen would be too weak to hold vacuum. Second, maybe most important, the electron beam is more like a water hose than a laser beam. An electric field focuses it to a point, and that point needs to coincide with the CRT inside surface. The focus electronics is simpler for a spherical surface because the beam length stays constant. Thirdly, for a similar reason, the scan/sweep electronics had to account for non-spherical beam lengths in order to maintain a constant transverse speed. Interestingly, they could also have moved the beam source farther back from the screen so the beam length was more constant. In other words, larger spheres have flatter surfaces. However, the market wanted thinner TVs they could set closer to the wall.
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