Since the second half of the year, ZTE Axon30 5G, Xiaomi MIX 4, Samsung Galaxy Z Fold 3 and other smart phones with the function of taking pictures under the screen have been released one after another, and new products of OPPO and vivo have also come one after another. Apple and Huawei have also laid out related patents before ... The off-screen camera entered the eve of the outbreak.
If Apple's iPhoneX puts forward the concept of full screen, and Samsung A8s opens the era of perforated screen, then the innovation wave of off-screen camera technology that really returns the full screen to the essence is completely led by domestic manufacturers. The world's first off-screen camera technical scheme and the first mass-produced off-screen camera phone are both from China.
Relying on collaborative innovation and R&D, domestic panel manufacturers and mobile phone manufacturers stand in the C position in off-screen camera shooting, and also occupy the first-Mover advantage in technology and market. As the main innovative contributor of off-screen camera technology, screen factory plays a key role in it. Judging from the released product performance, it can even be said that China's screen technology has led the global innovation direction and process for the first time.
What is the application and market prospect of off-screen photography technology? What are the technical difficulties? How do domestic manufacturers break through? What is the impact on the industrial chain? Around these topics, Wang Jiwei visited relevant people and discussed the behind of the innovation breakthrough of off-screen camera technology.
The market calls for a comprehensive screen
In order to pursue the integrity of the screen, from the early off-screen fingerprints to narrow borders, from Qi Liuhai to punching holes and water droplets, mobile phone manufacturers have killed "black edges" and "chin", but the front camera has become the only "fetter".
Some manufacturers try to solve the problem by sliding cover and mechanical lifting, but it also brings problems such as heavy fuselage and easy failure.
Consumers' desire for a full screen is urgent. According to the consumer research report released by ZTE Mobile, two-thirds of the respondents want to have a full-screen mobile phone, and the market has a high acceptance of full-screen mobile phones.
The pursuit of mobile phone manufacturers, or the hope of consumers, is actually that "full screen" can really return to its essence and real definition, that is, a complete screen.
This long-cherished wish was realized when ZTE released the world's first off-screen camera phone Axon 20 last year. As a result, the era of "true full screen" officially opened.
In the view of a mobile phone industry analyst, off-screen camera technology is optimistic. On the one hand, there are pain points in market demand, and the previous scheme destroyed the integrity of the screen to some extent.
On the other hand, the configuration of mobile phone hardware is more and more similar, and the innovation on the screen has once again become the focus of competition among mobile phone manufacturers, such as high pixel and high refresh rate, while the emergence of off-screen camera technology has become the main selling point for mobile phone manufacturers to further shape differentiation and marketing.
"After the off-screen camera technology matures, the competition of mobile phone manufacturers on the screen will enter a new stage, especially now mobile phone manufacturers generally build an ecosystem around smart phones. In the fields of mobile PC, big screen and smart wear, the role played by the screen will become more and more important. " The person said.
This year is regarded as the first year of camera shooting under the screen of smart phones. Since the second half of the year, ZTE, Xiaomi and Samsung have successively released off-screen camera phones, and related products of OPPO and vivo will be released soon. The off-screen camera war between mobile phone manufacturers is gradually heating up.
According to the analysis of CINNO Research, an industry research organization, with the continuous improvement and iteration of the off-screen photography scheme, it will become the two mainstream technologies in the future market together with the punching scheme. CINNO predicts that by 2023, the shipment of smartphones with off-screen cameras will be around 5%, which is a market space of 30-40 million.
"Compared with the previous period of 1-2 years from the introduction of bangs, water drop screens and perforated screens to occupy about 50% of the market, the off-screen camera solution is still subject to technical complexity and cost. With the further maturity of the solution, the cost will drop, and the speed of switching full-screen by mobile phone manufacturers may accelerate in the future. " The above-mentioned people in the mobile phone industry said.
An instant challenge
From 20 19, OPPO, vivo, Xiaomi and other manufacturers have demonstrated off-screen camera technology. Until last September, ZTE released the world's first mass-produced camera phone Axon 20, which marked the real landing of the camera technology under the screen.
The reason why the off-screen camera technology has not been effectively solved before is mainly because it can not effectively solve the most obvious contradiction of "display-light transmission (imaging)" on smart phones.
In order to improve the display quality, the increase of pixels will reduce the light transmittance and affect the imaging quality of the front camera. If the light transmittance is increased, a "screen window" will appear in the area of the front camera, which will affect the consistency of the screen and make it impossible to completely hide the front camera.
Therefore, the front camera area of several square millimeters has become a bastion of technology research and development.
Legend: OPPO demonstrated the off-screen camera technology-perspective panoramic screen at 2065 438+09 MWC. Since 20 19, OPPO has launched off-screen cameras for several times, with the goal of 100% full screen.
Legend: Recently, the off-screen camera technology displayed at the Future Imaging Technology Conference held by OPPO.
This area called "sub-screen" is different from the traditional screen. Compared with the transmittance of perforated screen above 85%-90%, the optical transmittance of sub-screen area is only 20% at present.
Zhou Hua, chief analyst of CINNO Research, said that off-screen camera technology faces three major challenges:
First of all, OLED pixel driving requires a large number of TFT devices and metal traces, and the size and number of these devices determine the screen transmittance in the front camera area.
Secondly, the structure of organic light-emitting diodes is complex, with more than a dozen layers, and the light transmittance of each layer is not 100%. Multi-layer superposition has a certain influence on light transmittance, especially at present, the flexible PI substrate is still yellow material, which has a great influence on imaging.
Third, because the gap between sub-pixels on the screen is small, the light is divided into grids. At the same time, the more light is divided, the more obvious the diffraction of linear light waves into light bands, which will eventually affect the pre-imaging effect, especially the blurring of portrait edges. Therefore, the existence of pixels leads to the inevitable diffraction problem of light.
These are just the problems caused by two screens made of different materials, and because these two different screens are different in design, structure and driving mode, considering the space requirement and cost control of module stacking, a driving IC is needed to achieve the consistency of color, brightness and frequency of the main and auxiliary screens under different structures, voltages and currents.
"It is difficult to achieve a consistent display effect without making people feel the existence of this sub-screen. Just like you have two different musical instruments, such as a saxophone and a piano, and then people make it sound the same, then this debugging is very difficult. " Lou Junhui, chief engineer of Visionox's off-screen camera technology, said.
Difficult road to innovation
In the words of Wang Jisi, chief engineer of ZTE's display planning, "the research and development of off-screen camera technology is an extremely cruel process."
This kind of "heart abuse" refers to constantly choosing a balanced solution to the problem in "display-light transmission".
For example, in the scheme of reducing the number of pixels and increasing the light transmittance, the PPI of the front camera area at the bottom of the screen will decrease, and it is necessary to increase the power at this position to achieve the same visual brightness as other positions, so this technology has certain requirements for the material of sub-pixels; The scheme of maintaining the number of pixels increases the light transmittance by reducing the area of each pixel, but the pixels in the under-screen area become smaller and the power increases, which also poses a certain challenge to the material life.
The above two schemes are not only easy to cause the problem that the service life is reduced due to screen burning, but also can not effectively solve the problem of light diffraction.
Therefore, at present, the mainstream solution to the pixel problem is to drive four groups of pixels through a group of TFT devices and routing technology, without reducing the light-emitting layer and enhancing the light transmittance, which can achieve consistent display effect when meeting the requirements of non-fine image quality, and there will be slight practical differences when meeting the requirements of fine image quality.
On the other hand, in order to solve the light transmission problem of the display material in the front camera area, we mainly change the display material (change it into a material with high transparency) on the premise of ensuring the brightness and color are consistent with the main screen, such as a transparent anode, without adding a polarizer, and introducing a transparent PI. The replaced material needs to be mass-produced.
The above mainly belongs to the problem-solving category of panel manufacturers.
This work is mainly done by mobile phone manufacturers. That is, through the combination of the hardware selection of the front camera and the self-developed algorithm, the camera level close to that of ordinary mobile phones can be achieved.
Therefore, it can be seen that the vision of off-screen camera is good, but it involves many technological innovations and belongs to system engineering. It requires a lot of collaborative research and development by panel and mobile phone manufacturers, and it takes many iterations to overcome this technical barrier. After solving the technical problems, mass production, yield and cost have become the "next ideal city" to be overcome.
Among several mobile phones currently released and displayed that adopt off-screen camera technology, ZTE Axon 20 and ZTE Axon 30 continue to maintain their first-Mover advantage, relying on the off-screen camera solution provided by Visionox, which is also the first solution to realize mass production in the world.
Legend: Xiaomi 20 19 released the "hidden screen" technology.
Legend: The off-screen photo effect of Xiaomi in 2020.
Legend: On August 10, Xiaomi MiX 4 was released with the off-screen photo scheme.
Xiaomi's MIX 4 adopts the scheme of Huaxing Optoelectronics, but Xiaomi's chairman and CEO Lei Jun publicly stated at the press conference that the screen yield is low and the cost is high because the 3D flexible screen adopts off-screen technology. According to Wang Jiwei, stores under the MIX 4 line plan to pick up the goods in September.
OPPO's off-screen camera solution is to cooperate with BOE, but no commercial products have yet come out.
Which screen technology is stronger?
At present, among many off-screen camera technology solutions, ZTE and Visionox are regarded as the more mature mainstream solutions by the industry.
The most important patented technology of this scheme is that the front camera area (sub-screen) adopts the array design of "one dragging many", that is, "1 sub-pixel driving circuit drives other sub-pixels with the same color at the same time", which can simplify the wiring design of transparent areas, greatly improve the transmittance, and make the mass production of off-screen camera technology possible. It is understood that this technology is the most critical underlying patented technology for "off-screen camera shooting" and the only way to break through mass production under the existing technical conditions.
"Compared with the' one-for-one' scheme introduced by other manufacturers in the industry, the' one-for-many' array design has broken through the existing drive architecture and needs creativity. The reason for choosing it is to pursue the optimal balance between display effect and mass production. " Lou Junhui stressed.
As the main promoter of off-screen camera mass production, Visionox has been little known behind the scenes. Until recently, Visionox took the stage for the first time and revealed the core of its off-screen camera technology.
In addition to pioneering the design of "one-drive multi-array", according to Lou Junhui, Visionox's off-screen camera technology also pioneered core inventions, including the edge setting of pixel driving circuit and the snake electrode routing scheme, which simplified the wiring in the sub-screen, suppressed the diffraction phenomenon and improved the photographic clarity of the camera.
Zhou Hua, chief analyst of CINNO Research, said that the most mature off-screen technology solution at present should be the off-screen technology that Visionox and ZTE are now cooperating with, including the similar technology used by Xiaomi. Zhou Hua thinks this technology should become the mainstream technology of off-screen camera shooting in the future.
Since 2006, Visionox has been researching transparent displays including PMOLED and HUD. From 20 17, Visionox began to explore the technology of off-screen camera. According to the current off-screen camera scheme, it has gone through 20 18 PMOLED+AMOLED scheme, 20 19 semi-AMOLED+AMOLED scheme, 20 19 transparent screen display color block scheme and 20 19 transparent screen small anode scheme.
Legend: Visionox's new generation off-screen camera solution InV see Pro presented at 20021World Display Industry Conference.
Due to years of accumulation in the field of organic light-emitting diodes and transparent display, Visionox has the largest number of patents granted and the earliest number of patent applications in the field of off-screen camera technology.
This is also the reason why Visionox successfully launched the world's first mass-produced commercial solution InV see for off-screen technology last year, and launched an upgraded solution InV see Pro this year to achieve rapid iteration and performance improvement of sub-screen resolution and transmittance, and continue to lead the development of off-screen camera technology. According to Wang Jiwei, Visionox's solution is the off-screen technical solution with the fastest iteration, the richest mass production experience, the highest yield and the most competitive comprehensive cost.
Who will benefit from the industrial chain?
Some insiders said that although the current off-screen photography scheme has a certain maturity, there is still room for optimization.
For example, in terms of improving transparency, Wang Jisi said that ZTE's next goal is to increase the light transmittance from the current 20% to about 30% on the premise of ensuring 400PPI pixels.
"Although there is only an increase of 10%, it is not easy. It is necessary to cooperate with camera selection and choose a better shooting algorithm to further enhance transparency and suppress diffraction. " Wang Jisi said.
In addition, the off-screen camera will also integrate more off-screen sensing technologies, such as off-screen 3D face recognition and off-screen ambient light sensing. Will make the integration of future mobile phones higher.
At the same time, the off-screen technology is still complicated and costly. According to Wang Jisi, ZTE's off-screen camera screen costs more than 50% higher than the perforated screen, and it needs to further reduce the cost through scale popularization in the future.
As the basic platform technology, the off-screen camera technology is the application direction. Whether it is a hard screen AMOLED off-screen camera, a flexible AMOLED off-screen camera, a high-end flexible off-screen camera, a medium-sized off-screen camera, etc., it can be applied to notebook computers, smart watches, smart bracelets and other products.
"For the above application scenarios, Visionox can provide complete solutions and have complete customized development capabilities for customer needs." Yan Junhui said.
As an innovative technology, what impact will the off-screen photography technology bring to the industry?
Lou Junhui said that there are four opportunities:
1. Materials: Because the materials involved in the off-screen camera technology are very different from the normal screen, there are opportunities in new materials. For example, transparent adhesive materials have the opportunity to replace traditional materials with poor transparency.
Second, the chip: Because the off-screen technology uses the main screen and the auxiliary screen, the drivers of the two screens should be consistent and the display effect should be consistent, which puts forward higher requirements for the chip. Although it is a challenge, it is an opportunity for chip manufacturers.
The third is the camera: the original camera is suitable for blind holes or through holes. Now because of the need to adapt to the transparent screen, we need a new camera to adapt.
Fourth, algorithm vendors: There are a large number of algorithm vendors with off-screen cameras in the industry.
The commercialization process is two years ahead of schedule.
Compared with before, the comprehensive in-screen technology innovation was mainly led by foreign manufacturers such as Apple and Samsung, while the change of in-screen camera technology was mainly promoted by China. ZTE, Xiaomi and OPPO became the first three manufacturers to mass-produce and publish off-screen technology, and behind them, they relied on the solutions of Visionox, Huaxing Optoelectronics and BOE.
As mentioned above, off-screen photography involves many technologies, such as screen materials, organic light-emitting diode devices, array design, driving algorithms, etc., which is a systematic innovation.
Especially for screen manufacturers, such innovation is extremely difficult. In the case that customers and material equipment manufacturers don't know what the real "off-screen camera" will be like, panel manufacturers need to design their own product forms, formulate standards, design research and development, purchase materials and test, which is difficult and risky.
"At that time, when we did this technology, there were no samples and certainly no products in the world, so we didn't have any reference. Our so-called solutions are all our own ideas, and then we try them ourselves. At that time, some people really questioned whether it could be done. Communication with foreign experts, facing customers and industrial chain, are questioned, and feel that the contradiction between display and light transmission cannot be solved. Until we show them a demonstration ... If we don't do this, the commercial process of off-screen technology will take at least 1-2 years. " Yan Junhui said frankly.
In this sense, the off-screen photography technology is the embodiment of the technological innovation strength of domestic panel manufacturers.
In the view of Li, chief analyst of Jiwei Consulting Display Industry, the innovation of domestic panel and mobile phone manufacturers in off-screen camera technology has directional guiding significance for the industry.
"On the one hand, it has played a role in cultivating the supply chain and guiding customers. With a clear direction of optimizing product performance in the supply chain, customers can also focus more energy and resources on the direction suitable for the efforts of terminal manufacturers. On the other hand, after the successful mass production of products, the research on its technology can help the industry to avoid many detours and reduce the cost of trial and error. Time and capital investment can be concentrated on proven solutions, which can accelerate the promotion and popularization of off-screen technologies. " Li said to him.
(Proofreading/Sami)