If you pay attention to the press conferences of mobile phone manufacturers in the past two years, there should be a "mysterious organization" at their flagship mobile phone press conferences-DisplayMate.
In 2019, the 90Hz high refresh screen on OnePlus 7 Pro received a DisplayMate A+ rating. Since then, DisplayMate has been active in major mobile phone manufacturers' press conferences, scoring mobile phone screens.
Prior to this, consumers judged the quality of mobile phone screens based on purely "compared to numbers": the higher the brightness, the better, the larger the resolution, the better, and the wider the color gamut, the better.
The popularity of DisplayMate scores has given consumers a basis for reference beyond the almost empirical "better than numbers", but this year, the score, which symbolizes the high-quality screen medal, is also difficult to distinguish the best screen.
Click on DisplayMate's score sheet and you will find that DisplayMate A+'s top rating is no longer uncommon. On the contrary, flagship phones that have not received an A+ rating seem to be rarer.
In Xiaomi's 11 series screen evaluation, DisplayMate evaluated it as "close to the textbook level of display accuracy and performance, and visually almost perfect."
At first glance, it seems to be a unique top evaluation, but if you look at OPPO Find X3 Pro, OnePlus 9 Pro, Samsung S20 Ultra, iQOO 8 Pro and other screen reviews, you can see the exaggeration of "close to the textbook level" Metaphor and A+ rating, this even includes the Redmi K40, which focuses on the mid-range market.
If you say that the current mobile phone circle has a strong internal volume, then the screen must be the most aggressive part of the flagship mobile phone: just after comparing the resolution and refresh rate, then you have to compete on the brightness, color reproduction and accuracy. The rule of survival of the fittest is crueler than any category.
Nowadays, it is difficult for you to see a bad screen on a flagship mobile phone. When everyone's screens are equally bright, "energy consumption" seems to be the next battlefield for flagship mobile phones.
Broke the traditional structure of more than ten years
Among the mobile phones currently on the market, Samsung's Galaxy Fold3 should be the closest to the future. The expensive price is destined to not be popular, but this does not prevent Samsung from using it to explore new forms of mobile phones.
▲ Fold prototype
In Samsung's vision, the Fold series was originally an attempt by Samsung to make larger screen phones after the Note series. At the beginning of Fold's development, it can be seen that the prototype was spliced together with two Note.
But now if you look at Fold3 again, you will find that Fold3 integrates many technologies that are at the forefront of the industry, including flexible folding screens, ultra-thin glass, under-screen cameras, waterproof hinges, etc. It seems that larger screens are no longer the ultimate goal of folding screens. , The folding screen is like an experimental field, used to verify and test the feasibility of various new "equipment".
There is also a less perceptible upgrade on Fold3. Its internal screen uses Samsung's latest Eco² OLED technology. According to the test data given by Samsung, the power consumption is saved by up to nearly 25%.
The screen is recognized as a big consumer of mobile phone power, and in the trend of high resolution and high refresh rate, "good" screen speeds up the speed of squeezing the battery. Therefore, it is particularly important to improve the battery life of the mobile phone and reduce the battery life of the mobile phone screen.
The key reason why Eco² OLED technology can significantly reduce power consumption is that it has changed the traditional three-layer structure of OLED screens that have been maintained for more than ten years-removing the middle polarizer layer, allowing the screen to brighten and save power.
Here we need to briefly introduce the polarizer. Compared to OLED screens, the application of polarizers in LCD screens will be more familiar.
When you take apart an LCD screen, you usually get two polarizers that look gray. Normally, the two polarizers will rotate and overlap by ninety degrees, so that the light from the back panel of the screen will be overlapped by the two polarizers. The polarizer is completely shielded, and a dark picture is obtained.
▲ The light path of LCD is very tortuous
The imaging principle of the LCD screen is to add a layer of liquid crystal molecules between the two polarizers, and use the electric field to control the twisting of the liquid crystal molecules to let the light "escape" from the blocking of the polarizers and light up the screen to display the image. Coupled with color filters, you can get color images.
For OLED screens, the role of polarizers is quite different. The characteristic of OLED screens is that each pixel can emit light independently, so there is no need to add a backlight panel behind, and the control of light intensity does not require the use of polarizers to block. Just control the luminous intensity of each individual pixel.
However, the manufacturer found that after removing the polarizer, the OLED screen had a serious problem-too reflective.
Since the cathode material used in the OLED film layer is often a metal material such as magnesium-silver alloy, the whole screen is like a mirror (or the inside of a heat preservation pot) after coating, which is very easy to reflect the ambient light, which greatly reduces the contrast of the OLED display. .
Therefore, the manufacturer added a circular polarizer under the screen. When external light enters the screen and is reflected, the polarization direction of the reflected light is perpendicular to the polarizer and cannot exit the screen through the polarizer, thus eliminating the reflected light inside the screen.
To put it simply, the OLED polarizer is added to reduce the reflection of external light, so Samsung’s Eco² OLED removes it, will the phone "blind" the user's eyes?
Less is more
When Samsung introduced the Eco² OLED technology, they mentioned that they adopted a new technology to encapsulate the OLED screen, so that it can greatly reduce the reflection of the screen on the OLED layer, but did not disclose much about the specific technical details.
According to Omdia analyst David Hsieh, Samsung is likely to adopt COE technology (Color On
Encapsulation), plating a layer of color film on the OLED to absorb the reflected light, thereby replacing the polarizer.
The principle is that after removing the polarizer, a color film is applied to the red, green, and blue OLED sub-pixel layers to filter light. When the color film encounters reflected light, it can intercept and absorb it.
In addition to Samsung, screen suppliers such as BOE and Tianma are also studying their own non-polarizer packaging technology, and strive to make a breakthrough in the form of OLED screens. Why do everyone have to struggle with polarizers?
Take Fold3 as an example. According to Samsung's experiment, the light transmittance of Fold3's screen has increased by 33% after removing the polarizer, which is intuitively reflected in the increase in screen brightness.
This is because the light transmittance of the polarizer itself is not strong. If the OLED needs high brightness to adapt to the strong light environment, it must use higher power consumption to make up for the attenuation of light when it passes through the polarizer.
Therefore, under the same brightness, the power consumption without the polarizer is significantly lower, which is a victory from the physical level.
Another benefit of removing the polarizer is to make the screen of the phone thinner. The thickness of the circular polarizer used in OLED screens is generally about 100 microns, and because the COE technology is only a layer of coating, the thickness can often be controlled at 10 microns, which can effectively reduce the thickness.
The thinner the screen, the lower the bending radius when folded, and it is not easy to form wrinkles and creases. It can be said that this is a screen technology facing the era of future folding screens.
On the other hand, a screen with a substantially increased light transmittance is also conducive to the development of under-screen lens technology.
Are we finally able to use the camera under the screen? As mentioned in the article, one of the main reasons for restricting the development of the under-screen lens is that the light input of the lens is too low. When the light transmittance of the screen is increased, the practicality of the under-screen camera will also be enhanced. (Although Samsung's under-screen performance is still very average)
I want the horse to run, and I want the horse not to eat grass
Brightening the mobile phone screen is a contradictory process. Users want higher brightness without sacrificing battery life. Manufacturers have to start with display principles, materials and structures to solve this problem of having both fish and bear's paws.
Apple uses LTPO (Low Temperature Polycrystalline Oxide) technology in Apple Watch Series 5, which supports adaptive adjustment of the refresh rate of the OLED screen, which can reach as low as 1Hz when the picture is static. The corresponding technology is also used in Samsung Note 20 , OPPO Find X3 Pro and other top screens.
When Xiaomi 11 was released last year, it highlighted the use of Samsung E4 luminescent material screen. Compared with E3 luminescent material, the power consumption can be reduced by 15%, and the peak brightness and contrast ratio have been improved, allowing consumers to pay attention to the screen material for the first time. The impact on the display.
However, less than a year after Xiaomi 11 dominated, iQOO 8 Pro announced the use of Samsung’s new E5 luminescent material, which has a theoretical power consumption of 25% lower.
In addition to replacing the new materials, iQOO 8 Pro also processed the mobile phone screen. Before the screen was packaged, a layer of microprisms was fabricated on the screen using a low-temperature lithography process, and the light emitted by each pixel was more focused after being refracted. Make the screen brighter and more transparent.
If you compare the current mobile phone with the iPhone 4S 10 years ago, you will find that the battery life of the two has not been improved by leaps and bounds. Both require one charge a day or even two charge a day. Therefore, many people are complaining about the mobile phone promotion. The reduction in power consumption is all false propaganda.
At the same time, few people mentioned that today's mobile phones have too many functions compared to the past. The screen is about to occupy the entire palm, the resolution refresh rate is soaring, the CPU computing power is almost excessive, and the battery life is still sufficient. Level, this is the result of the accumulation of "10% reduction in power consumption" each time.
From the past point of view, the landing of new display technologies is often accompanied by changes in the shape of mobile phones. Just as the flexible screen packaging technology during the iPhone X period gave rise to full-screen designs, Samsung's non-polarizer packaging technology this time is likely to promote the under-screen cameras and Folding screen technology is mature.
New requirements will detonate new technologies, and new technologies will lead to new requirements. If you think that the current form of mobile phones is too boring, please be patient and wait, because a new technology rolls up the wind of change. Has gradually taken shape.
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