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LG's new 1Hz display is the secret behind a new laptop's battery life

pcworld.com

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Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#81

Post by adgjlsfhk1 »

hedora wrote: post #53
hirako2000 wrote: post #9

Earlier quoted context omitted.

Dell needs to sell these XPS. The AI button doesn't do the trick, so battery life may do it.

What's the real-world battery life though? My mac gets 8 hours real world; 16 in benchmarks; 24 claimed by apple. Assuming the xps has the same size battery, and this really reduces power consumption by 48%, I'd expect 16 hours real world, 32 in benchmarks and 48 in some workload Dell can cherry pick.

Dell has to deal with windows cuts that in half with all the slop and spyware.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#82

Post by vlovich123 »

hedora wrote: post #51
hacker_88 wrote: post #49

Earlier quoted context omitted.

Copying , Draw() is called 60 times a second .

It isn't for any reasonable UI stack. For instance, the xdamage X11 extension for this was released over 20 years ago. I doubt it was the first.

Xdamage isn’t a thing if you’re using a compositor for what it’s worth. It’s more expensive to try to incrementally render than to just render the entire scene (for a GPU anyway).

And regardless, the HW path still involves copying the entire frame buffer - it’s literally in the name.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#84

Post by fc417fc802 »

saltcured wrote: post #45
fc417fc802 wrote: post #14

Earlier quoted context omitted.

> This seems just as challenging, i.e. having a "sync to vblank" that can adapt all the way down to 1 Hz? I was under the impression that modern compositors operated on a callback basis where they send explicit requests for new frames only when they are needed.

There are multiple problems here, coming from opposite needs. A compositor could request new frames when it needs them to composite, in order to reduce its own buffering. But how does it know it is needed? Only in a case like window management where you decided to "reveal" a previously hidden application output area. This is a like older "damage" signals to tell an X application to draw its content again. But for pow…

I mean sure, you raise an interesting point that at low enough refresh rates application architectures and display protocols begin needing to explicitly account for that fact in order for the system as a whole to make use of the feature.

But the other side of things - the driver and compositor and etc supporting arbitrarily low frequencies - seems like it's already (largely?) solved in the real world. To your responsiveness point, I guess you wouldn't want to use such a scheme without a variable refresh rate. But that seems to be a standard feature in ~all new consumer electronics at this point. Redrawing the entire panel when you could have gotten away with only a small patch is unfortunate but certainly not the end of the world.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#85

Post by quantumink »

adgjlsfhk1 wrote: post #81
hedora wrote: post #53

Earlier quoted context omitted.

What's the real-world battery life though? My mac gets 8 hours real world; 16 in benchmarks; 24 claimed by apple. Assuming the xps has the same size battery, and this really reduces power consumption by 48%, I'd expect 16 hours real world, 32 in benchmarks and 48 in some workload Dell can cherry pick.

Dell has to deal with windows cuts that in half with all the slop and spyware.

Last I checked: the XPS was one of the few laptop product lines offering native Linux (Ubuntu) as an alternative default configuration option to order

It's how I got mine about 6-7 years back anyways, still works great (except the battery) ...never let windows get it's claws into the machine in the first place

Edit: to add, I realized over time that having a battery that lasts longer just can't seem to beat my older laptop experiences: being able to just swap an extra battery in and have full charge at will (without soldering and all that 'ish) In that sense I feel that the future is coming full circle to modularity, swapability, repairability - to the point they're becoming my primary considerations for the next portable computing select I will need to acquire.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#86

Post by snthpy »

topspin wrote: post #76
Filligree wrote: post #42

Earlier quoted context omitted.

Why? Surely copying the same pixels out sixty times doesn't take that much power?

The PCWorld story is trash and completely omits the key point of the new display technology, which is right in the name: "Oxide." LG has a new low-leakage thin-film transistor[1] for the display backplane. Simply, this means each pixel can hold its state longer between refreshes. So, the panel can safely drop its refresh rate to 1Hz on static content without losing the image. Yes, even "copying the same pixels" costs…

Thanks. Great explanation.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#87

Post by alok-g »

qnleigh wrote: post #32

> That will help save enormous amounts of power: up to 48 percent on a single charge, Why does refresh rate have such a large impact on power consumption? I understand that the control electronics are 60x more active at 60 Hz than 1 Hz, but shouldn't the light emission itself be the dominant source of power consumption by far?

I used to be a display architect about 15 years back (for Qualcomm mirasol, et al), so my knowledge of the specifics / numbers is outdated. Sharing what I know.

High pixel density displays have disproportionately higher display refresh power (not just proportional to the total number of pixels as the column lines capacitances need to be driven again for writing each row of pixels). This was an important concern as high pixel densities were coming along.

Display needs fast refreshing not just because pixel would lose charge, but because the a refresh can be visible or result in flicker. Some pixels tech require flipping polarity on each refresh but the curves are not exactly symmetric between polarities, and further, this can vary across the panel. A fast enough refresh hides the mismatch.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#88

Post by msephton »

gowld wrote: post #77
bracketfocus wrote: post #28

Earlier quoted context omitted.

From what I understand, the laptop will reduce the refresh rate (of the entire display) to as low as 1Hz if what is being displayed effectively “allows” it. For example: - reading an article with intermittent scrolling - typing with periodic breaks

Articles have animated ads, though.

On such an article it would not go down to 1Hz. It's checking if the image is changing or not.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#89

Post by alok-g »

londons_explore wrote: post #36
nmstoker wrote: post #27

Sorry, might be obvious to some, but is that rate applied to the whole screen or can certain parts be limited to 1Hz whilst others are at a higher rate? The ability to vary it seems like it would be valuable as there are significant portions of a screen that remain fairly static for longer periods but equally there are sections that would need to change more often and would thus mess with the ability to stick to a lo…

With current LCD controllers but new drivers/firmware you could selectively refresh horizontal stripes of the screen at different rates if you wanted to. I don't think you could divide vertically though. Don't think anyone has done this yet. You could be the first.

I believe E-ink displays do this for faster updates for touch interactivity. Updatimg the whole display as the user writes on the touch screen would otherwise be too slow for Eink.

Re: LG's new 1Hz display is the secret behind a new laptop's battery life

#90

Post by __d »

jauntywundrkind wrote: post #19
jerlam wrote: post #2

Haven't phones, watches and tablets been using low refresh rates to enable battery improvements for a while? The Apple Watch Series 5 (2019) has a refresh rate down to 1Hz. M4 iPad Pro lacks always-on display despite OLED panel with variable refresh rate (2024): https://9to5mac.com/2024/05/09/m4-ipad-pro-always-on-display...

Panel Self Refresh should largely just work, and I believe has been on laptops for a long long time. Here's Intel demo'ing it in 2011. https://www.theregister.com/2011/09/14/intel_demos_panel_sel... I'm not sure that there's really anything new here? 1Hz might be lower. Adoption might be not that good. But this might just be iteration on something that many folks have just not really taken good advantage of till now.…

I’m not an expert here, but …

CRTs needed to be refreshed to keep the phosphors glowing. But all screens are now digital: why is there a refresh rate at all?

Can’t we memory-map the actual hardware bits behind each pixel and just draw directly (using PCIe or whatever)?

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