After the iPhone 12 conference was over, in addition to the various qualities of the iPhone itself, which were discussed a lot, many users still regarded it as a pity that the high refresh rate screen was not used.
After all, the high refresh rate screen has been an important selling point of flagship mobile phones since 2019. It has appeared in major manufacturers' press conferences. The high refresh rate does bring a smooth experience. As for why Apple did not introduce a high refresh rate screen on the iPhone 12, the widely discussed reason is battery life.
The addition of the 5G chip will indeed have a certain impact on the battery life of the mobile phone. This problem is very likely to be solved on the next-generation iPhone by relying on the LTPO OLED screen that supports dynamic variable refresh rate.
At present, Samsung has used this screen on the S21 Ultra 5G. It was also reported that Apple will apply it on the next-generation iPhone, and Samsung is the corresponding screen supplier.
High refresh rate screen, can also take into account battery life?
Samsung S21 Ultra 5G is not the first electronic product to use LTPO screen. Apple actually used LTPO technology as early as Apple Watch 4, mainly to maintain the battery life after the screen is enlarged.
LTPO is a new screen backplane technology in the industry. Compared with another OLED backplane technology, IGZO, it can dynamically adjust the refresh rate of the screen, and even flexibly change between 1Hz and 60 Hz, thereby reducing screen power consumption.
And this technology has to wait until Apple Watch 5 to mature on Apple Watch. In the previous evaluation , we mentioned the answer of Apple engineers:
In addition to LTPO itself, this function also requires the cooperation of subsystems, including the driver and power manager, which have been redesigned on Apple Watch Series 5.
This is the "always on screen" function on Apple Watch 5, and the battery life will not crash.
The reason why Apple did not apply this technology to the iPhone as soon as possible is not due to Apple. In Samsung, as a new technology, the effect and yield rate of LTPO on large screens were not very good before, and Apple could not do it even if it wanted to.
Here you might think of the iPad Pro, which also has a high 120Hz refresh rate and a dynamically variable refresh rate, even with a larger screen. But don’t forget, the iPhone uses an OLED screen, while the iPad Pro uses an LCD screen.
The iPhone 12 has now all used OLED screens, and the LCD screen lags behind the OLED screen in contrast, color gamut range, default color temperature, color accuracy, etc. to a certain extent. For the sake of high refresh rate or dynamic refresh rate, re-use LCD , It is not wise to look at it.
Coupled with the power consumption killer of 5G chips, battery life is indeed not easy to solve. In recent years, the battery capacity of iPhone has shown an overall upward trend, but new screens such as OLED, the increase of screens, and the introduction of 5G are all consumed With this part of the increased battery capacity, battery life has not increased significantly.
However, it seems that cost and yield should not be a big issue. Samsung has maintained 2K resolution and 120Hz high refresh rate in S21 Ultra 5G at the same time. It can be said to make up for the regret of the previous generation of products, and also used 10 -120Hz LTPO screen with dynamic variable refresh rate.
As one of the world's largest screen manufacturers, Samsung has applied a large number of new technologies on its flagship phones, and I believe it is mature enough.
However, in the short term, the next-generation iPhone may be the same as Samsung, only applying this technology in the high-end version. According to a report by South Korean electronics industry media The Elec, Apple will apply LTPO technology to the two Pro models in the 2021 iPhone series. .
The entire series of applications will wait until 2022, when LG may also participate as one of the screen suppliers. The LTPO OLED screen used on the iPhone is likely to be used in the iPad series in Apple’s usual style.
The screen is an important part of the flagship product
At present, the biggest significance of LTPO screen applications on mobile phones is to reduce power consumption and improve battery life, so that high-resolution and other qualities can coexist with high refresh rates on the same screen, and improve user experience.
So how does it reduce power consumption? This also starts from the meaning of the high refresh rate screen itself. Whether it is a 90Hz or 120Hz refresh rate screen, it is compared with a common 60Hz refresh rate screen.
In unit time, 60Hz screen can show 60 frames of pictures, while 90Hz and 120Hz refresh rate screens can show 90 frames and 120 frames respectively. The amount of content displayed per unit time increases, and the pause decreases, so it looks smoother.
▲Swiping is one of the application scenarios that best reflects the advantages of high refresh rate screens. Picture from: Sharp
But obviously there are many application scenarios in addition to sliding when we use mobile phones. Do they all require a 90Hz or even 120Hz refresh rate? The answer is obviously no.
For example, when watching a video, the video content itself does not support 90Hz or even 120Hz refresh rate, even if it supports 60Hz B station, it can only be used after opening the VIP service.
One of the reasons why Lee Ang's 120-frame movie "Gemini Killer" failed to get a good box office was because the frame rate increased, the information increased, and the fighting scenes were too smooth and clear, and some users called it no "movie feel."
▲ "Gemini Killer" with a lot of details and too smooth has not been recognized
Obviously, high frame rate content still needs to be adjusted in content performance and even performance methods.
Reading is one of the most common scenes when we use mobile phones. Since the screen content is fixed, high frame rate content is obviously not needed. At this time, variable frame rate is very important. Lowering the frame rate does not affect the viewing experience.
In addition, the sense of fluency is also related to the frame generation time. This concept is often used in the game field. It refers to the time that a frame of screen is generated. It is also the calculation of 60 frames per unit time. The shorter the frame generation time, the shorter the frame generation time. The smoother.
The variable frame rate is equivalent to the lock frame rate in the game. After the frame rate is locked, the computing resources consumed by the system are also reduced, which is another way of reducing power consumption.
Of course, the LTPO screen still needs other hardware and even system software support, otherwise the frame rate conversion is not sensitive enough, it will appear that the original 60Hz display interface has become 30Hz, and the screen pauses a lot, but it looks like a freeze. The gain is not worth the loss.
Apple still has some experience in this regard. In addition to the Apple Watch 5 mentioned above, Apple's Promotion technology applied on the iPad Pro has achieved a relatively good level.
Although the iPad Pro uses an LCD screen, it also supports a 120Hz refresh rate. Promotion also brings a variable refresh rate. iMore has done an experiment on the iPad Pro, opening the video and sliding interface at the same time on the split screen interface.
This 24-frame video did not conflict with fast sliding, forming a sense of fragmentation.
In addition, the iPad Pro now supports a 240Hz touch sampling rate, which obviously brings a better experience. It is not difficult to see from the above cases that Apple can take advantage of the variable refresh rate brought by the LTPO OLED screen. To the point.
As the part of mobile phones that has the most contact with users, the screen is also an important part of the power of mobile phone products. Under the background of domestic mobile phones hitting high-end, it is more and more indispensable to improve the screen quality, and the wave of high refresh rate screens Domestic mobile phone manufacturers took the lead in launching.
▲ The important selling point of Mi 11 is the screen
In the foreseeable future, high-quality, high-refresh rate screens will become more and more common, and the supporting software ecosystem will also need to evolve.
Behind the high refresh rate screen, the software ecology also cannot be ignored
We mentioned two problems to be solved in the previous review article on high refresh rate screens. One of them is the battery life problem caused by the increase in display content and the substantial increase in power consumption. After the official application of the LTPO screen, the problem A certain degree of relief can be obtained.
But another problem is not so simple, and that is the supporting software ecosystem.
At present, regardless of the 90Hz or 120Hz high refresh rate screen, the application scenarios on the mobile phone are not too much except for the daily sliding. This is why we feel that compared with the reduction of battery life, choosing a high refresh rate screen is not necessarily cost-effective.
Even the most valued game field with high refresh rate is also restricted by mobile games. As a sophisticated small device, mobile games are not much open to high frame rate games, and 60 frames are the norm.
A few games like "QQ Speed" that support 90Hz refresh rate are not available to all models, even if it is on the iPad side, "QQ Speed" already supports 120Hz, but compared to the overall game market, it is still a minority.
And another problem is the limitation of mobile phone performance. As we pointed out in our previous article on Xiaomi Mi 11 game test , it is inevitable to encounter frame drop when running "Yuan Shen" at the highest quality for a long time, not to mention the higher 90 It's even 120 frames.
This is not to deny the experience improvement brought by the high refresh rate, but its customized meaning is stronger than the universal meaning, which requires the support of more developers.
Of course, the Android camp still has a certain first-mover advantage over iOS. After all, the Android mobile phone application has an earlier high refresh rate screen. As the ecological controller, Google has also launched a series of supporting documents.
For example, the common frame synchronization technology in games refers to the synchronization of the operation logic in the game with the operating system and display hardware. Android's display design can avoid jitter when the display hardware switches new frame content.
At the same time, the document also mentions that a dynamically variable high refresh rate screen can further enhance the experience.
▲ Picture from: Tech talk today
Once Apple uses a high refresh rate screen on the next-generation iPhone, with the app store’s grip on developers and Apple’s appeal, there is still a chance to catch up with the Android camp.
The investment in high refresh rates by the two major mobile giants, iOS and Android, can also further promote the maturity and even popularization of high refresh rate software content.
▲ Galaxy Z Fold 2. Picture from: Wordless Tech
In fact, this can also be seen as an advance preparation for the folding screen ecology. After all, the stylus has been considered as one of the best accessories for folding screen phones before. The larger screen gives it better writing possibilities. The high refresh rate and high sampling rate can also make the pen more "following".
At the beginning of the application of high refresh rate screens in mobile phones, in addition to the voice of experience improvement, there were also many doubts about it, and only after power consumption and even software ecology are completed, the doubts will become less and less.
Until then, the high refresh rate screen can be considered mature.
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