This was the original purpose of screensavers, which saved your screen from damage. Displaying a dynamic image prevented one part of the screen from being overused.
¹ It was actually an interlaced field, not a frame, but that too much nitpicking.
Means something very different now.
If the majority of the blue you see in the world is the sky and the sea, would you just start to think of blue as a blank? If you just consider blue as something more like we consider white, then any competing hues dominate what you describe. So just like white with the tiniest bit of red becomes pink, a purplish sea becomes red?
It worked fine, felt like a huge waste of money. But it weighed over 100 pounds!
We're both just as bad as each other, the meaning is discernible.
I had a small apartment so my desk/office area was a corner of the living room and I could run an HDMI cable over to use it as a secondary monitor for watching stuff on the computer. Even the fact that it would display 1080i was a huge jump from my previous bargain bin TV.
It was the days of Windows Media Center and it was before cable companies got rid of Clear QAM channels so I found that I could just take the shared cable in my 3-apartment house and hook up to a cheap Hauppauge card for tuner, guide, and DVR. Add a cheap USB IR receiver/remote and it was like having the "good" cable with the bells and whistles (but with a better interface and for free).
Eventually got an HDTV when prices came down and income went up, but a few years ago when a girl I knew was looking for a CRT to set up a retro gaming station for her young daughter, I donated all 111 lbs. of it gladly. That thing is probably still going.
On LCDs, I still can see faint flicker on some static backgrounds, and I think 60 Hz might play a role here too—though it seems to also depend on the brightness and Flux being on or off. E.g. on https://marctenbosch.com/news/
(temporal dithering usually is visible as slight noise on darker shades)
PAL and 50 Hz TV are not synonymous. Brazil has 60 Hz AC and uses PAL-M which is 60 Hz TV. AC=TV even in these odd cases.
Old CRTs couldn't possibly clock their flyback to anything but mains.
Cheap LEDs like some holiday minilights are rectified so they'll flicker at 60 Hz and I can't stand them.
When I get rich and have lots of free time, I'll probably buy a bunch of old CRTs just to dig to the roots of this.
I remember playing MoH:AA, the play experience was quite out of this world.
This basically calibrated the thing to look normal... with the magnet there. It took quite a while to restore to normal.
No? Huh, guess it was just me ;)
No idea how the previous owner managed to magnetize it, it never happened to me.
15 years later it is still the case I use today, even though I am thinking about replacing it. Doesn't get much carrying today though.
There is also a navbar (back/home/recent buttons). In my case it's a white-ish rectangle that's almost always present on screen. By the time Samsung added an option to hide it, the damage was already done.
I have them both burnt in on my screen. I first noticed them after merely 1.5 years of using the phone.
OLED burn in is a 100% real thing.
I've still yet to see an LCD that performs as well as those CRTs, though.
This was not necessarily wanted in OLD CRTs, where the startup sequence could take a while (and possibly other factors, such as reducing the lifespan, but I'm not sure about this).
Funnily, we are starting to see a bit of a comeback of these in OLED smartphone that have an always-on display to show time and a few things: the illuminated portion generally moves over time.
You can see some burn-in on old phones, in the notification areas, the taskbar for computers, or sometimes the always-on TV panels at airports or train stations.
They suffered terrible burn-in, and I was never sure why they were used. Eventually they ripped them out and replaced them with panels using the same technology (monochrome panels made of amber LEDs) that is used in the rest of the network for displaying information.
The thing about information is that you don't want it to spin or hop about, it needs to remain perfectly still while a potentially large number (tens of thousands of people use the station in an hour, if anything goes wrong all those people want information) stare at the information and so it can't avoid burn in. I can see that for the advertising screens, the opportunity for huge full colour screens is worth the risk of burning in an image, and worst case you could in theory even charge an advertiser who insists on holding a single image for the cost of repairing/ replacing your screens. But the information screens don't much benefit from colour, the pixel-addressable LED screen is only a small improvement over prior electro-mechanical devices which of course couldn't burn in, why allow burn-in just to get a colour screen? Maybe they were cheap?
Also, cue trainspotters and such putting 10-hour+ 1x-speed captures of the screens running through the entire cycle up on YouTube...
Even old TV shows look better than ever, as long as they were scanned from film. Look at the original Star Trek or Twilight Zone on Blu-Ray.
How are you watching a film on DVD if it hasn't been transferred to digital?
Update: It appears that the original motivation was public terminals/machines.
BTW, the "black" on a CRT is almost a true black. The electron beam is off when the signal voltage is less/equal to the black level, there's no "black light" if the black level is perfectly calibrated. Displaying a black image fullscreen is indistinguishable from an endless vertical/horizontal blanking interval from a practical standpoint. There's a measurable decrease in power consumption, although it's not much (it can be great enough on a large TV, though).
On the other hand, VESA blanking mode turns off additional circuitry, and it can save a lot of power while still keeping the CRT heater on, suspending the screen without the disadvantages of a long wakeup time or stressing the tube.
They were going to redesign the Apple operating system, and started with the screensaver.
It was a very cool screensaver, but I’m not sure how much progress they made beyond that.
Sorry.
(Someone should do a better version.)
A CRT screen basically works by firing electrons (or if you want that a bit more scaremongery: a beam of beta radiation) at the phosphor plate, the impact of which makes it emit light. Shades are achieved by varying the intensity of the electron beam and colour is formed by having three different colours of phosphor dot and three beams (and a grid to make sure the right dots were hit by the right electrons), but these details are irrelevant to the burn-in problem.
See https://en.wikipedia.org/wiki/Cathode-ray_tube for a longer and better explanation of how it works, and the history of the technology.
Under normal operation this is mostly all fine: the phosphor "recovers" once the beam stops hitting it for a while. The phosphor does degrade (essentially they burn) a little over time with use which is also fine if the wear is level, though it does mean the screen effectively fades a little with age. If you leave a particular image on screen for a long time then it becomes more of a problem because the lit areas degrade and the unlit ones don't. Essentially the phosphor plate develops permanent tan lines. It was not uncommon to see the shadow of login prompts or semi-permanent UI elements burned into screens this way.
It happens to other screen types too, though for slightly different reasons in each case. Plasma screens are particularly sensitive to the problem, but it can affect LCD displays too (some types worse than others). See https://en.wikipedia.org/wiki/Screen_burn-in for examples and a bit more detail.
The earliest screen-savers were just turned the screen black. This could lead to machine being powered off accidentally (potentially losing work if a user had walked off without saving) when someone thinks they are off and tries to turn them on, so instead a simple moving message was added, the message to indicate the machine is intentionally on and the movement to stop the message burning in. Other animations were added, with After Dark's iconic flying toasters appearing in ~89, and around the Windows 3.x era it exploded and almost became an art form (anyone else fondly remember the three-and-two-tenths flying toaster brigade, or Johnny Cast-Away?), some people competed to have the best screen-saver, or just the most "them" screensaver along with wallpaper/colour-scheme/other-desktop-customisations, and of course every corporate desktop carried the (bouncing) company branding when idle. Things died down when we became more energy conscious: going back to black screens because turning the whole apparatus off when idle saves energy.
The energy waste, battery degradation, and keeping the CPU/GPU awake longer are all huge wastes. Sadly, screensavers are nothing but wasteful nowadays.
I guess plasma is the main reason why on-screen channel logos went from solid to translucent?