From the end of 2021 to the beginning of 2022, in addition to Qualcomm Snapdragon 8 Gen 1 becoming the talk of digital enthusiasts after dinner, LTPO, a relatively unfamiliar "word", has also been repeatedly put on the table, in addition to having enough voice among geek enthusiasts, at several conferences at the end of the year, mobile phone brands even use equal length and performance to talk about this technology.
On the stage, manufacturers are full of enthusiasm to publicize what "power saving" advantages can be brought by mobile phones after adopting LTPO technology.
Offstage is that consumers will still face various problems of electricity, caton and battery life when using Android mobile phones.
LTPO, that is, while keeping the screen high refresh, reduces unnecessary power consumption by "adaptive" refresh frame rate, so as to achieve power saving.
However, the ideal is very full, and the reality is very bone.
On the one hand, mobile phone manufacturers for third-party APP software scheduling is different, if the use of LTPO features to do a good job of software scheduling, it is indeed able to reduce some power consumption losses in specific scenarios; but if it is not done well, not only does it cost electricity but also increases the sense of visual fragmentation, which is equivalent to a double-edged sword.
In addition, if you want to perfectly adapt to third-party APP, manufacturers need to spend a lot of energy, after all, the number of commonly used software base is huge, the characteristics of each software are different, where the frame rate needs to be reduced, where it is necessary to maintain a high refresh, how to switch the frame rate of the second-level three-level switching interface with minimal sense of fragmentation, etc., are all needed for deep adaptation.
On the other hand, for game scenarios where large power consumers need to maintain a high refresh frame rate, LTPO can play a very limited role.
Why can various mobile phone terminal manufacturers still treat LTPO as a treasure for crazy publicity, and even LTPO has not yet become the standard of mobile phones, LTPO 2.0 is coming, it seems that without LTPO, it is not enough to flagship mobile phone standards.
Where is the LTPO artifact?
Users interested in screen display technology should be familiar with the current mainstream screen material, the current mainstream screen material is OLED and LCD, these two screen applications have their own advantages and disadvantages on mobile terminals.
Whether it is LCD or OLED, various mobile phone terminal manufacturers have long taken screen refresh as the main selling point, in this new equipment track, the higher the screen refresh rate of whoever has it, the more they can occupy the high-end discourse power.
However, the problem that arises is that if the high refresh rate is always maintained, which is a problem for the pressure and battery load of the processor, how can it ensure the refresh rate and reduce unnecessary power consumption losses, so that the mobile phone can save more power?
Screen Material The picture comes from the web
Dynamic refresh may be the key "way" to solve this problem, so that the screen response can be "changed on demand" according to the user's use of the scene, such as 24 frames when playing movies; 1 frame when reading books or comics; and 60 frames or even 120 frames full frame when sliding pages.
At this time, LTPO appeared, which is fully called "low-temperature polycrystalline oxidation".
In fact, it can not be counted as a new technology, Apple Apple Watch 4 has taken the lead in adopting a variable refresh screen, which can be instantly increased from a constant 1Hz to 60Hz when waking up.
Both Apple Watch 5 and Apple Watch 4 support LTPO Image from Apple's official website
LTPO is a "hybrid" solution applied to the OLED TFT backplane, and to understand this technology, it is necessary to start with the mainstream TFT backplane technology.
At present, the TFT used in portable devices mainly has three technologies: a-Si, LTPS, IGZO, a-Si is called amorphous silicon, which is widely used in mobile phone screen displays because of low cost and high yield, covering high, medium and low price products in the early stage. However, in terms of carrier mobility performance related to the advantages and disadvantages of TFT and display power consumption, it is only 0.3-1 cm/V·S (the higher the data, the more power-saving).
With the iterative upgrading of technology and the upgrading of consumer demand, low-temperature polysilicon materials are slowly moving towards the main stage, that is, LTPS. In addition to the power consumption advantage of high mobility and reduced drive voltage, the response speed is also very fast, but the yield is low and low, which limits the large-screen device to carry this technology.
This requires the proMotion on the iPad Pro, which does not use LTPS material, but uses IGZO, which has a carrier mobility of only one-tenth of the former, on the one hand, cost considerations, on the other hand, because of the characteristics of IGZO itself, its leakage is also better than LTPS, and the refresh rate is more stable.
LTPO, as the name suggests, is a technology that forms the Oxide layer through a series of technologies on the LTPS layer. It has both LTPS high mobility and low power consumption, and IGZO low refresh stability low leakage characteristics, and then simple metaphor, LTPO is equivalent to combining the advantages of two materials.
In addition, public research data shows that LTPO can reduce the power consumption of terminal equipment by 5%-15%, although the paper data is beautiful, but in fact, it still depends on the specific use scenario, away from the use of the scene of power consumption, for the user, the significance is not great.
What is LTPO and what is LTPO 2.0
At present, the changes in LTPO 2.0 in hardware technology are not obvious, and "2.0" emphasizes more like the "optimization" of different use cases. In other words, LTPO 2.0 may only allow users to have a sense of LTPO technology, and LTPO when it first came out of the various manufacturers can "unified caliber" different, 2.0 is more like the product of each "in-depth customization", can be understood as hardware + software optimization after the technology.
If you do different frequencies in different scenes, such as running at a full frame of 120 frames when brushing Weibo; running at a standard frame of 24 frames when watching a movie; and displaying at 10 frames or lower when reading article content, it is not difficult.
Liu Fengshuo Weibo The picture is from Weibo
The difficulty is how to balance the scheduling frame rate between displaying content and fingering when in touch.
The frame rate scheduling logic for LTPO 2.0 is not the same, Xiaomi in the 12 series in addition to the regular application of different scenes dynamically adjust the refresh rate, but also according to the speed of the finger sliding screen, to achieve sliding speed. OnePlus' LTPO 2.0, according to them, is the real LTPO 2.0.
OnePlus Liu Fengshuo also said on Weibo: "Not a thing, OnePlus's LTPO 2.0 in addition to its own joint Samsung customization, contains a large number of cool self-developed technology applications, so that the screen experience in many aspects has been reached a new height."
OnePlus pointed out that the problems currently encountered by LTPO are that the recognition of complex overlay scenes is low and the matching speed is not fast enough, for example, typing scenes are scenes that will be applied every day in daily life. Under normal circumstances, the system will detect that this is a "typing" requirement, so it will increase the frame rate to 120 frames, but the problem is that it does not need to be maintained at 120 frames, and the LTPO 2.0 of OnePlus has a major advantage, you can dynamically adjust the frame number according to the screen display content while detecting the scene, and the moment of typing down is increased to a high frame rate, and the moment of leaving is reduced to 1 frame.
The refresh rate under different applications of Xiaomi pictures are from Xiaomi
But in this millisecond, the additional power consumption that can be reduced can really be perceived?
According to the friends around and the measured data, the equipment using LTPO 2.0 does not save much power, and it is not difficult to see from the measured data in the digital blogger's rice evaluation that the model equipped with LTPO and the ordinary mobile phone cannot pull out the gap in battery life.
Image from a screenshot of the rice review video
Rice said in the LTPO 2.0 review: "From the perspective of power saving, LTPO does a good job to a certain extent, it does save power, but this part of the power consumption for the overall battery life of the mobile phone, how much to improve in the end still has to play a big question mark." For some heavy mobile game players, the cliff-like decline in power can still be intuitively experienced.
Whether it is LTPO or LPTO 2.0, it is in a "dormant" state when facing the game scene.
Is the Gospel of Deep Gaming Enthusiasts a Standalone Display Chip?
Mobile phone brands such as Black Shark and iQOO, which are loved by heavy mobile game players, have found a new way to achieve the purpose of "reducing power consumption" by increasing hardware, that is, independent display chips are built into mobile phones.
In fact, this is not after the large-scale popularization of smart phones, only to install "independent display chips" in mobile phones.
As early as 2007, Nvidia launched the GeForce 5500 for mobile phones, which can achieve high-specification video decoding, support high resolution and 3D game performance, but limited by the function and game software support, and failed to play the strength of this chip.
Black Shark Mobile 2 Pro Image from Black Shark official website
As a result, this business strategy soon failed.
Today, 15 years later, mobile games are developing rapidly, high capacity, high picture quality, multiplayer screen is a major trend, for the current mobile phone performance is a big test, in the running of games such as "Original God", "Call of Duty Mobile Game Edition" and other games, often need the mobile phone processor "full load running", which brings additional heat and battery loss for the mobile phone.
How to ensure high refresh while reducing load loss is the most headache for mobile phone manufacturers at present, and at this time, the independent display chip comes in handy.
Taking iQOO 9 Pro as an example, the high-frame low-power mode is based on the principle of only letting the GPU render half the frame number, and then doubling the overall frame number through interpolation, such as rendering 45 frames to achieve 90 frames, and 60 frames to achieve 120 frames, so that you can improve the smoothness of the picture at the same time, but also let the phone in a low load state. The Boost Frame Rate mode is to insert one frame in the two frames of the low-frame game, which enhances the fluency on the basis of the original.
The use of standalone display chips on mobile phones is mainly to improve the frame rate
Judging from the recent launch of the flagship new machine equipped with Qualcomm 8, some manufacturers have begun to use LTPO+ independent display chip dual hardware configuration. In the mass use scenario, the LTPO mechanism is used to achieve the purpose of power saving; in the entertainment scene, the independent display chip is used to further reduce power consumption.
The iQOO 9 Pro is one of the few flagships with LTPO and monochromatic chips
This seems to be one of the few "hardcore" ways to improve the battery life of mobile phones at present.
But it is a pity that the screen resolution of the general scene can be adjusted adaptively, and the GPU load of the game scene can be reduced, but the Android GPU is still maintained in a state of high-speed operation.
If the GPU processor is "synchronized" with the screen refresh to instantly increase or decrease, the light will lead to sensory stuttering, and the heavy will tear the screen, so in order to "maintain stability", the GPU has to be fixed in a high-frequency operating state.
Apple LTPO is from the processor - system - UI for deep matching, of course, this also needs to be due to the processor itself power consumption control is good, LTPO is the "icing on the cake".
Again, if Android does not force control and deeply adapt from the "core" root, then even if the refresh frame rate scheduling is more accurate, and the switching between different applications is smooth, it is because of the processor itself, which is a large power consumer, so that the dynamic adjustment of the screen becomes better than nothing.