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a display architect about 15 years back (for Qualcomm mirasol, et al), so my knowledge of the specifics / numbers is outdated.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

There's definitely a few reasons but one of them is that you have to ask the GPU to do ~60x less work when you render 60x less frames

Your GPU rendering 1 frame vs your GPU rendering 60 frames.

I think the idea is that in an always-on display mode, most of the screen is black and the rest is dim, so circuitry power budget becomes a much larger fraction of overhead.

Really disappointing to only learn this after a decade, but on Linux changing from 60hz to 40hz decreased my power draw by 40% in the last hour since reading this comment.

I interpreted that bit as E2E system uptime being up by 48%. Sounds more plausible to me, as there'd fewer video frames that would need to be produced and pushed out.

This is an OLED display, so I don't think the control electronics are actually any less active. (They would be for LCD, which is where most of these low-refresh-rate optimizations make sense.)

The connection between the GPU and the display has been run length encoded (or better) since forever, since that reduces the amount of energy used to send the next frame to the display controller. Maybe by "1Hz" they mean they also only send diffs between frames? That'd be a bigger win than "1Hz" for most use cases.

But, to answer your question, the light emission and computation of the frames (which can be skipped for idle screen regions, regardless of frame rate) should dwarf the transmission cost of sending the frame from the GPU to the panel.

The more I think about this, the less sense it makes. (The next step in my analysis would involve computing the wattage requirements of the CPU, GPU and light emission, then comparing that to the KWh of the laptop battery + advertised battery life.

Before OLED (and similar), most displays were lit with LEDs (behind or around the screen, through a diffuser, then through liquid crystals) which was indeed the dominant power draw... like 90% or so!

But the article is about an OLED display, so the pixels themselves are emitting light.

It doesn't. They take extreme use cases such as watching video until the battery depletes at maximum brightness where 90% of power consumption is the display. But in realistic use cases the fraction of power draw consumed by the display is much smaller when the CPU is actually doing things.

Phones and watches do that with LTPO OLED which I don't believe exists at higher screen sizes although I'm not sure why. This is supposed to be special because it isn't OLED so should be able to get brighter and not have to worry about burn in.

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

OLED iPad dont have always on because of burn-in. Considering people certainly use it as photo frame, notification and time daahboars, kitchen recipe book, etc.

Less of a problem for iphones that unlikely to stay for a week in the same place plugged in and unused.

>M4 iPad Pro lacks always-on display despite OLED panel with variable refresh rate (2024):

Brightness, Uniformity, Colour Accuracy etc. It is hard as we take more and more features for granted. There is also cost issues, which is why you only see them in smaller screens.

iPad Pro only goes down to 10 FPS. This may be the display of the upcoming MacBook Pro.

What LG is pitching here is basically bringing that 1Hz floor capability to large laptop panels

Yes but I’m unaware of larger ones.

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. There's perhaps signficiant display tech advancements to get the Hz low, without having significant G-Sync style screen-buffers to support it.

One factor that might be interesting, I don't know if there's a partial refresh anywhere. Having something moving on the screen but everything else stable would be neat to optimize for. I often have a video going in part of a screen. But that doesn't mean the whole screen needs to redraw.

> Oxide (metal-oxide TFT)

Ok, that makes some amount of sense. The article claims this is an OLED display, and I haven't heard of significant power games from low-refresh-rate OLED (since they have to signal the LED to stay on regardless of refresh rate).

However, do TFT's really use as much power as the rest of the laptop combined?

They're claiming 48% improvement, so the old TFT (without backlight) has to be equivalent to backlight + wifi + bluetooth + CPU + GPU + keyboard backlight + ...

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

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.

Today it's mostly "all-or-nothing" at the panel level, but under the hood there's already a lot of cleverness trying to approximate the behavior you're describing

It's for OLED screens, so there's no backlight, but also no persistence.

These are self emissive pixels.

You're not moving your mouse 100% of the time. Probably less than 25% of the time. Probably using your keyboard less than 25% of the time. It doesn't need to degrade experience OR selectively refresh part of the screen (which it certainly doesn't).

It just proved the author knows nothing about either technology.

It’s truly unusable. What a mess the web has become.

Just activate Reader Mode immediately.

What these variable refresh panels are trying to do is kind of the "best of both worlds"

How is this a but? This is exactly what you want: the screen refreshes only when a new content appears or once a second.

A low refresh rate probably still requires the same display-side framebuffer as PSR.

With conventional PSR, I think the goal is to power off the link between the system framebuffer and the display controller and potentially power down the system framebuffer and GPU too. This may not be beneficial unless it can be left off long enough, and there may be substantial latency to fire it all back up. You do it around sleep modes where you are expecting a good long pause.

Targeting 1 Hz sounds like actually planning to clock down the link and the system framebuffer so they can run sustain low bandwidth in a more steady state fashion. Presumably you also want to clock down any app and GPU work to not waste time rendering screens nobody will see. This seems just as challenging, i.e. having a "sync to vblank" that can adapt all the way down to 1 Hz?

I wouldn't get a mini LED laptop for creative work. We have a mini LED TV, and manufacturers need to choose one of these two problems because of physical limitations:

- The LEDs for a mostly dark region with a point source are too bright so the point source is the correct brightness. Benchmark sites call this "blooming" and ding displays for it, so new ones pick the other problem:

- The LEDs for mostly dark regions with a point source are too dim so the black pixels don't appear gray. This means that white on black text (like linux terminals) render strangely, with the left part of the line much brighter than the right (since it is next to the "$ ls" and "$" of the surrounding lines). Also, it means that white mouse pointers on black backgrounds render as dark gray.

For creative work, I'd pick pretty much any other monitor technology (with high color gamut, of course) over mini LED. However mini-LED is great if you have a TV that is in direct sunlight, since it can blast watts at the brightest parts of the screen without overheating.

Firefox Android + ublock origin. There's ads on the internet? Wouldn't know.

And if Apple introduced it a decade ago, then it's at least five years older than that.

What's new here is the 1 Hz minimum.

Apple might have convinced some gullible customers that this was something new.

But to the rest of the world variable refresh rate existed for years by then. As is with most Apple "inventions".

In this case the patent goes back to 1982: https://patents.google.com/patent/US4511892A/en

Apple doesn't manufacture panels, they buy from others. I wonder how Apple can claim they have this feature.

Stroke CRT displays been able to do variable refresh rate since like the 80s, quite the omission there buddy.

You can use CRU (custom resolution utility) to add 50Hz to most screens.

Ostensibly any display capable of VRR should be able to operate at any range.

For sample-and-hold panel technologies like LCD and OLED, refresh is about updating the pixel state (color). There is a process that takes place for that even when the pixel data remains unchanged between frames. However, the pixels still need to emit light between refreshes, which for LCD is a backlight but for OLED are the pixel themselves. The light emission is often regulated using PWM at a higher frequency than the refresh rate. PWM frequency affects power consumption as well. Higher PWM frequency is better for the eyes, but also consumes more power.

E-ink displays can do this. That's why they're used in ereaders. Display in TFA OTOH emits light, so definately not.

It does, especially with LCDs like this, where the backlight is the primary driver of the power consumption of the panel.

I'm not even sure how they got their 48% figure. Sounds like a whole-system measurement, maybe that's the trick.

If the screen is only refreshing once per second, less energy is used to refresh the screen. The pixel uses the same amount of power.

Read the article.

The display has a refresh rate of 120hz when needed. The low refresh rate is for battery savings when there is a static image.

Variable refresh rate for power savings is a feature that other manufacturers already have (apple for one). So you might already be an early adopter.