If you're in the market for a smartphone or smartwatch, now's a good time to learn a new tech term: LTPO. The screen technology is an improvement to conventional displays and might well arrive in next-generation iPhones later this year.
LTPO stands for low temperature polycrystalline oxide. That mouthful translates to better battery life on premium mobile devices. LTPO allows displays to refresh at high rates, for fluid games and smooth scrolling. It's also efficient at low rates for times when a phone's screen pixels aren't changing.
Apple wouldn't be the first phone-maker to use LTPO technology, which is already in some of its Apple Watch devices. Samsung's Galaxy Note 20 Ultra, Galaxy Z Fold 2 and Galaxy S21 Ultra; Oppo's Find X3 Pro; and OnePlus' 9 Pro all take advantage of the technology.
Why would you want LTPO?
One way to improve smartphones these days is with high refresh rates that rapidly repaint the screen. The usual rate is 60 times per second (60Hz), but high refresh rates can reach 90Hz or 120Hz. The quick refresh rates make for smooth scrolling and help games look their best. But high refresh rates require a lot of power, which is why many phones supporting it allow users to disable it for better battery life.
LTPO helps by gracefully accommodating both high and low frame rates that bottom out at one screen refresh per second for super high efficiency. An earlier technology called LTPS, short 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," Display Supply Chain's Ross Young said of LTPO. "Otherwise it's going to cost you in terms of power."
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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 in the display.
LTPO is a "best of both worlds" approach to backplanes that performs well when the transistors are on and when they're off. It combines three advantages: high resolution, an adjustable refresh rate, and "ultra-low power consumption," said Strategy Analytics analyst Jeffrey Mathews. But it comes with a 5% to 10% price premium.
What it doesn't replace is a display's separate system for generating light, for example, backlit light-emitting diodes (LEDs) or active-matrix organic light-emitting diodes (AMOLED). So don't be surprised to hear phone-makers say they're using both AMOLED and LTPO.
Why is Apple interested in LTPO?
LTPO is a great match for Apple's ProMotion display technology, which offers variable refresh rates that can reach up to 120Hz. Promotion is only offered on iPads today, but several analysts including David Hsieh of Omdia, say the iPhone 13 (or whatever Apple calls it) will employ LTPO at least on Pro models.
Apple already has LTPO experience with its Apple Watch. The company first used LTPO in the Apple Watch Series 4 in 2019. It became important with the Apple Watch Series 5, allowing ultraslow refresh rates for an always-on watch face that didn't sacrifice too much battery life. Apple holds some LTPO patents.
"They have it on the watch and use ProMotion on the iPad Pro," Display Supply Chain's Young said. When the iPhone 13 is announced, Apple "could make a big push and make a lot of noise about it."
Apple didn't respond to a request for comment.
What about LTPO tablets, laptops, and TVs?
Young expects LTPO in tablets and eventually laptops, as display manufacturers embrace the technology. "A lot of fabs are converting or adding LTPO capacity over the next couple of years," he said.
But don't expect LTPO in large displays. The crystalline requirements mean big sizes aren't economical compared with amorphous silicon (a-Si) layers that are used in larger displays. Also, TVs are plugged in, so there's no battery life advantage to justify LTPO's higher price.
Who makes LTPO displays?
Samsung Display supplies LTPO screens for phones, while LG Display and Japan Display make them for smartwatches. Many more suppliers are coming, including Sharp in Japan and BOE, Visionox, TCL CSOT, Everdisplay and Tianma in China, Mathews says.
How much power does LTPO save?
LG Display reported a 71% power savings when dropping from a 60Hz refresh rate down to 1Hz, and Sharp said power usage dropped 67% on its LTPO displays when going from 120Hz to 1Hz, Young said of companies' research findings.
That's a pretty big drop, especially since displays are the biggest users of battery power in phones. But the display is only on when you're using the phone, so LTPO won't give you triple the battery life. And you'll get different power savings depending on how you use your phone. Reading an e-book with static pages can use a very low refresh rate most of the time, but playing graphically intense games needs a high refresh rate. And actual savings will depend on software and power management hardware that can rapidly change the refresh rate in different circumstances.