Krogoth wrote:Airmantharp wrote:This is it, in a nutshell. It ain't ready for the kind of static output that dominates desktop computing, where CRTs had a 'degaussing' function that would eliminate any 'burn-in' that accumulated.
(remember that screensavers were created as a software solution to help deal with the CRT burn-in problem, and they've stuck with us, but they weren't even necessary for the last decade or so of CRT use)
Degaussing doesn't remove burn-in. It just removes any coloring issues arising from EMI sources.
Close, but not quite.
The problem that degaussing was intended to solve was residual magnetization of the
shadow mask, caused by external
static magnetic fields (not EMI). This residual magnetism would deflect the electron beams from their intended path, resulting in color shifts as the beams hit the wrong phosphor dots. A magnetized shadow mask was typically the result of nearby speakers with unshielded magnets, or permanent magnets in toys, fridge magnets, and the like.
The magnetic fields from EMI -- being much weaker, and alternating in nature rather than static -- would not tend to result in any residual magnetization of the shadow mask.
Related CRT trivia: The Earth's magnetic field -- while not strong enough to produce problematic magnetization of the shadow mask -- can cause perceptible (a degree or two) rotation of the screen image if the monitor is oriented with the electron beams parallel to the field (i.e. with the screen facing north or south). I remember pointing this out to a co-worker back in the day, after they mentioned that their screen image was slightly rotated. I swiveled the monitor 90 degrees on their desk, and the rotation disappeared. Really freaked them out.