Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

pcworld.com

Post reply on HN
Print view View original

61–70 of 186 posts

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

#61

Post by karlgkk »

hedora wrote: post #50
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?

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…

> The more I think about this, the less sense it makes

And yet, it’s the fundamental technology enabling always on phone and smartwatch displays

The intent of this is to reduce the time that the CPU, GPU, and display controller is in an active state (as well as small reductions in power of components in between those stages).

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

#62

Post by stonogo »

hedora wrote: post #56
serious_angel wrote: post #8

> LG’s press release leaves several questions unanswered, including the source of the “Oxide” name... > Source: https://www.pcworld.com/article/3096432 [2026-03-23] --- > HKC has announced a new laptop display panel that supports adaptive refresh across a 1 to 60Hz range, including a 1Hz mode for static content. HKC says the panel uses an Oxide (metal-oxide TFT) backplane and its low leakage characteristics to keep t…

> 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 equiva…

The article says this is an LED panel and LG is working toward an OLED version.

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

#63

Post by giancarlostoro »

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.

At the software level yes, but it seems nobody has taken the time to do this at the hardware level as well. This is LG's stab at it.

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

#64

Post by hedora »

whalesalad wrote: post #47
dizzy9 wrote: post #44

Perhaps it can do 50Hz, which may be beneficial for emulating PAL systems.

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

You don't need VRR for this, but there are some step functions of usefulness:

24Hz - now you can correctly play movies.

30Hz - NTSC (deinterlaced) including TV shows + video game emulators.

50Hz - (24 * 2 = 50 in Hollywood. Go look it up!) Now you can correctly play PAL and movies.

120Hz - Can play frame-accurate movies and NTSC (interlaced or not). Screw Europe because the judder is basically unnoticeable at 120Hz.

144Hz - Can play movies + pwn n00bs or something.

150Hz - Unobtanium but would play NTSC (deinterlaced), PAL and movies with frame level accuracy.

240Hz - Not sure why this is a thing, TBH. (300 would make sense...)

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

#65

Post by hedora »

layer8 wrote: post #54
amelius wrote: post #15

So if a pixel is not refreshed, it doesn't use any power?

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…

OLED is fundamentally not sample and hold, because it is using PWM, right?

Ignoring switching costs, keeping a sample-and-hold LED at 0%, 50% and 100% brightness all cost zero energy. For an OLED, the costs are closer to linear in the duty cycle (again, ignoring switching costs, but those are happening much faster than the framerate for OLED, right?)

(Also, according to another comment, the panel manufacturer says this is TFT, not OLED, which makes a lot more sense.)

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

#66

Post by ksec »

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...

>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.

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

#67

Post by thelastgallon »

hedora wrote: post #50
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?

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…

Not OLED.

> LG Display is also preparing to begin mass production of a 1Hz OLED panel incorporating the same technology in 2027.

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

#68

Post by thelastgallon »

ricardobeat wrote: post #26

Apple introduced variable refresh rate back in 2015. That’s over a decade ago, I’m sure there’s some new tech involved here, but quite the omission.

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

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

#69

Post by layer8 »

hedora wrote: post #65
layer8 wrote: post #54

Earlier quoted context omitted.

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…

OLED is fundamentally not sample and hold, because it is using PWM, right? Ignoring switching costs, keeping a sample-and-hold LED at 0%, 50% and 100% brightness all cost zero energy. For an OLED, the costs are closer to linear in the duty cycle (again, ignoring switching costs, but those are happening much faster than the framerate for OLED, right?) (Also, according to another comment, the panel manufacturer says th…

PWM still counts as sample-and-hold, because it sustains the brightness throughout the duration of a frame, resulting in significant motion blur. The converse are impulse-driven displays like CRT and plasma.

LED backlights using PWM likewise don’t change the sample-and-hold nature of LCD panels.

My understanding is that PWM switching costs aren’t negligible, and that this contributes to why PWM frequencies are often fairly low.

Post reply on HN