Apple iPhone 13 Pro should interest you in LTPO displays

IPhone 13 Pro Phones

Apple; illustration by Stephen Shankland / CNET

This story is part of Apple event, our comprehensive coverage of the latest Apple news.

The IPhone 13 Pro models are the first Apple smartphones to use the ProMotion feature to help graphics and text slide smoothly when you scroll. This means that now is the time to learn about the screen technology called LTPO that allows it.

LTPO stands for Low Temperature Polycrystalline Oxide. That bite translates to better battery life on high-end mobile devices. LTPO allows screens to refresh at high rates when playing video games, scrolling through social networks, or swiping to switch apps. But for static information like the text in an eBook, LTPO can slow refresh rates to save battery life.

On the iPhone 13 Pro and Pro Max, LTPO allows ProMotion to adjust screen refresh rates from 10 times per second (10 Hz) to 120 Hz. ProMotion “produces fast frame rates when you need them and preserves the life of the monitor. battery when you don’t need it, ”Apple chief marketing officer Greg Joswiak said at Tuesday’s conference. IPhone 13 launch event.

Apple isn’t the first phone maker to use LTPO. Samsung Galaxy Note 20 Ultra, Galaxy Z Fold 2 and Galaxy S21 Ultra; Find X3 Pro from Oppo; and OnePlus’ 9 Pro all take advantage of the technology. LTPO is also built into some Apple Watch screens.

Here’s an overview of what LTPO is and how it works.

Why would you want LTPO?

One way to improve smartphones these days is to use high refresh rates that quickly repaint the screen. The usual rate is 60 times per second (60Hz), but high refresh rates can reach 90Hz or 120Hz. Fast refresh rates allow smooth scrolling and help games look their best. But high refresh rates require a lot of power, which is why many phones that support it allow users to turn it off for better battery life.

LTPO helps by adapting gracefully to high and low frame rates that reach a screen refresh level per second for extremely high efficiency. With a earlier technology called LTPSShort for low temperature polysilicon, displays flicker distractingly at low refresh rates.

“If you want a high refresh rate phone, this is the way to go,” Ross Young of Display Supply Chain said of LTPO. “Otherwise, it’s going to cost you dearly in terms of horsepower.

Apple didn’t specifically say it was using LTPO, but that’s the only way to deliver ProMotion’s capabilities on the iPhone, Young said.

What exactly is LTPO?

LTPO is a new way to build the backplane, one of the key layers of a digital display. Backplanes house thousands of transistors, the tiny on-off switches that control how pixels produce light on an adjacent layer of the screen.

LTPO is a “best of both worlds” approach to backplane that works well when the transistors are on and when they are off. It combines three advantages: high resolution, adjustable refresh rate and “ultra-low power consumption,” said Jeffrey Mathews, analyst at Strategy Analytics. But it comes with a 5% to 10% price premium.

What it does not replace is a separate display system for generating light, such as backlit light emitting diodes (LEDs) or active matrix organic light emitting diodes (AMOLED). So don’t be surprised to hear phone makers say they use both AMOLED and LTPO.

Why is Apple interested in LTPO?

LTPO is a perfect match for Apple’s ProMotion display technology, which offers variable refresh rates of up to 120Hz. Apple already offered ProMotion on some iPads, and several analysts, including Omdia’s David Hsieh, have been expecting ever since. months before their launch to see LTPO on iPhone 13 Pros.

Apple already has LTPO experience with its Apple Watch. The company first used LTPO in the Apple Watch Series 4 in 2019. It has become important with the Apple Watch Series 5, allowing ultra-slow refresh rates for an always-on watch face, which didn’t sacrifice too much battery life. Apple holds LTPO patents.

But Young was a bit disappointed with Apple’s approach to the iPhone 13 Pro. “As a display geek, I was surprised that the Pro models don’t go down to 1Hz like the OnePlus 9 Pro,” he said. Apple probably didn’t do this due to display flickering issues below 10Hz, but “I hope this will be fixed soon and implemented next year,” he said. .

Apple did not respond to a request for comment.

Apple Watch Series 5

The Apple Watch Series 5 uses an LTPO screen that refreshes as slowly as once per second to conserve battery power.

Angela Lang / CNET

What about tablets, laptops and LTPO televisions?

Young expects LTPO in tablets and eventually laptops as display makers embrace the technology. “Many factories are converting or adding LTPO capacity over the next two years,” he said.

But don’t expect LTPO on big screens. Crystalline requirements mean that large sizes are not economical compared to the amorphous silicon (a-Si) layers used in larger displays. Plus, TVs are plugged in, so there’s no battery life benefit to justify LTPO’s higher price tag.

Who manufactures LTPO displays?

Samsung Display provides LTPO displays for phones, while LG Display and Japan Display manufacture them for smartwatches. Many more vendors are coming, including Sharp in Japan and BOE, Visionox, TCL CSOT, Everdisplay and Tianma in China, Mathews said.

How much energy does LTPO save?

LG Display reported a 71% power saving by going from a refresh rate of 60Hz to 1Hz, and Sharp said power consumption fell 67% on its LTPO displays from 120 Hz to 1 Hz, Young said of the companies’ search results.

That’s a pretty big drop, especially since screens are the biggest users of battery in phones. But the screen is only on when you are using the phone, so LTPO won’t give you triple the battery life. And you will get different energy savings depending on how you use your phone. Reading an eBook with static pages can use a very low refresh rate most of the time, but playing graphically intense games requires a high refresh rate. And the actual savings will depend on power management software and hardware that can quickly change the refresh rate under different circumstances.

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