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Re:Show HN: Make my screen black by onion2k on Monday December 20, 2021 @06:24AM (#29623605)
Making your screen all black saves energy.

For many monitors this is not true. For a screen where the resting state of the LCD pixels are open displaying black means the monitor has to switch the diffuser to closed in order to block the light, which uses more energy than displaying white. There are lots of different LCD technologies which affect whether black or white is more efficient. For CRT screens black is always better.

https://www.scientificamerican.com/article/fact-or-fiction-b...

Re:Show HN: Make my screen black by vbphprubyjsgo on Monday December 20, 2021 @11:17AM (#29626517)
And the backlight (presumably 99% of power usage) is on no matter what you do with your pixels.
Re:Show HN: Make my screen black by stavros on Monday December 20, 2021 @08:52AM (#29624920)
My second screen (an LG) turns the backlight off whenever it's all black. My Dell monitors don't do the same, and it's a shame. It's always on but effectively off all the time as it usually is all-black, and thus there's no backlight.
Re:Show HN: Make my screen black by vbphprubyjsgo on Monday December 20, 2021 @11:29AM (#29626670)
> My second screen (an LG) turns the backlight off whenever it's all black.

Did you test that setting every pixel black actually triggers this? Most OS just shut the monitor after inactivity (by ceasing to output video signal, or something like that).

Re:Show HN: Make my screen black by stavros on Monday December 20, 2021 @11:31AM (#29626698)
Yes, it happens within seconds. It's not VESA blanking.
Re:Show HN: Make my screen black by vbphprubyjsgo on Monday December 20, 2021 @11:33AM (#29626725)
That's a huge misfeature, then. Is it a computer monitor?

Ahh maybe you are referring to dynamic contrast (which is still a misfeature).

Re:Show HN: Make my screen black by stavros on Monday December 20, 2021 @11:38AM (#29626814)
It's a computer monitor, yes. I don't know about a misfeature, I love it. What's dynamic contrast?
Re:Show HN: Make my screen black by vbphprubyjsgo on Monday December 20, 2021 @11:54AM (#29626987)
I have never seen a monitor that turns off with a black screen (aside from dynamic contrast mode). What happens when the screen needs to turn back on? Does it freeze for 1-3 seconds?

> What's dynamic contrast?

Shutting certain backlights to raise the contrast between the dark side of the screen and the lit side. It has various undesireable side effects such as the darkening and lightening giant areas unexpectedly. They often try to make the transition gradual which just makes the screen even less real-time.

Re:Show HN: Make my screen black by stavros on Monday December 20, 2021 @03:17PM (#29629723)
> What happens when the screen needs to turn back on? Does it freeze for 1-3 seconds?

No, it takes around 200ms for it to turn back on.

> Shutting certain backlights to raise the contrast between the dark side of the screen and the lit side.

Ah, no, there are no sections in this one, the whole backlight turns off and on.

Re:Show HN: Make my screen black by mathrall on Monday December 20, 2021 @09:04AM (#29625034)
Great read, it would definitely help us on the long run.