Not long ago, the announcement of OPPO's off-screen camera technology seems to have made many friends see the "truly comprehensive" hope: the camera is hidden under the screen, which does not affect the normal display of the screen, and the front camera only starts to work when needed. If this technology can be mass-produced, the aesthetics, weight and thickness, body compactness and equipment efficiency of full-screen mobile phones will be improved.
In fact, as early as 2065438+June 2008, OPPO applied for a patent called "image processing module, camera and electronic equipment", which can be inferred that OPPO began to solve the real full screen last year and actively carried out relevant patent reserves. From the figure, we can roughly see the design principle of the camera under the OPPO screen: the screen of the front camera can transmit light, and when the camera is not used, the projection component will fill the light-transmitting area for display.
Now, the front camera can be hidden, the receiver can be replaced by screen sound, and the light/distance sensor can also be hidden under the screen. So 100% true full-screen is really here? In fact, even if the camera under the screen is mass-produced, the screen ratio will not increase much compared with the current mechanical structure full screen. Because there are still three technical problems to be solved-
1, screen pack
I believe everyone has such a question: Why do Android phones generally have chins when they can be made narrower? In fact, it's not that manufacturers don't want to lose their chins, but they have to do it. First of all, we need to pay attention to the packaging technology of the screen.
At present, the screen packaging technology used in mobile phones can be divided into three types. One is COG package, and the driver chip on the screen extends directly, so a chin is needed to place related components. This technology is applied to early screen packaging, such as iPhone 8；; ; The second is COF package, in which a part of the driver chip is made flexible, and some components can be turned to the lower side of the screen, thus reducing the chin. This packaging scheme was widely used in previous full-screen mobile phones.
IPhone X copper package
The third is the COP package, where all the driver elements are folded under the screen and the chin is cancelled by folding the screen. Because the screen needs to be folded, the body will become thicker. At present, this technology can be realized by Samsung, and a large number of screens of iPhone X are ordered from Samsung. Why are domestic mobile phones rarely encapsulated by COP? The reason is also very simple. The price of three or four thousand domestic mobile phones is difficult to digest the high cost of COP packaging.
2. Antenna clearance area
At the Lenovo Z5 conference, Chang Cheng, vice president of Lenovo Group, mentioned that it's not that I don't want to raise the screen ratio to a higher level, but that I have to sacrifice the call if I don't want a chin. The reason is that almost all smart phones need a signal clearance area to ensure the omni-directional communication effect of the antenna.
Design of non-full screen mobile phone antenna
In detail, conductive metal can reflect, absorb and offset electromagnetic waves, so when designing mobile phone antenna, we should not only stay away from metal components, but also isolate batteries, oscillators, shields, cameras and other noise reduction components. This clean area where the antenna is placed is the clearance area of the antenna. The screen is equivalent to a metal layer, and the electromagnetic radiation frequency band generated by the display work covers the working frequency band of the antenna, so the increasing screen ratio is contradictory to the sufficient signal clearance area.
In the era of full screen, the antenna clearance area is reduced.
Generally speaking, the longer the antenna, the lower the frequency channel it can cover. After the space of the antenna is squeezed, the low frequency is most affected, resulting in the narrowing of the total bandwidth. In the future, 5G technology needs more low frequencies and multiple antennas to ensure signal strength.
So how did iPhone X make chin disappear? It is understood that iPhone X balances signal loss by using LCP antenna substrate with lower electromagnetic loss. But what is the actual signal of iPhone X? It has been listed for a long time, and I believe everyone has a vision. The reason is not only that Apple adopts two brands of baseband, which reduces baseband performance, but also related to the redesign of signal headroom.
3. BM area of the screen
In fact, even if the problems of screen packaging and antenna clearance area are solved, it is difficult to achieve a 100% screen ratio for a full-screen mobile phone.
Nubian mobile phones have a concept called borderless on both sides. Embodied in Nubian's flagship machine, it really presents a visual effect without borders on the left and right. But in fact, there are no borders on the left and right sides, but the black edge of the screen is very narrow, which is well hidden visually through the refraction of 2.5D glass. This black border, commonly known as BM area, still cannot be cancelled.
It is difficult to completely align the LCD screen during assembly. These errors will cause bright edges around the screen, which is commonly known as screen light leakage. The function of BM area is to prevent light leakage. In addition, another function of BM area is to accommodate the circuits connecting pixels and control units around it, which is why there is no light leakage problem on the self-luminous organic light-emitting diode screen, but there are also black edges on the screen.
So 100% full screen is basically impossible with the current technology. Seeing this, I believe that readers and friends will not be deceived by the rendering or disclosure of the manufacturer.