This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl.
ZTE's AXON 20 5G, the world's first smartphone with an integrated front camera display, has no camera visible on its 6.9-inch display. We talked to ZTE officials to find out how the camera is embedded underneath the screen, which displays text and photos, and what kind of technology they use to ensure that it doesn't interfere with photography.
The Rakuten BIG is also manufactured by ZTE and we assume that they use the same technology.
The display of a typical smartphone is not transparent. So even if we had a camera built underneath the display, it would be impossible to take a picture with it. ZTE has worked with display manufacturers to develop a "transparent display" and has succeeded in achieving this difficult task. But it's not a simple technology. There were five technological developments that went into making it a reality.
1. Transparency of materials
Displays in smartphones are made up of electrodes and other components superimposed on the top and bottom of the display. The general structure of an OLED display consists of protective glass, a polarizer, sealing glass, electrodes (anode), an OLED panel, electrodes (cathode), and a glass substrate. Even if a camera is placed underneath the display, it is not possible to photograph the outside of the display.
The AXON 20 5G allows the camera to be placed underneath the OLED display by making the electrodes transparent. This means that when you use the camera, you can turn off the display and photograph the outside of the phone from the camera that's embedded inside.
2. Development of proprietary chipsets
The part of the display in which the camera is embedded has a lower resolution than the rest of the entire display. This requires the use of a chipset to constantly synchronize the display so that it does not shift. ZTE has the know-how to develop various chipsets as well, and they have developed a proprietary chipset that can control multiple (camera and other) parts of the display to be in sync with each other on a single display.
3. Optimization of circuit wiring
The display has a mesh of circuit wiring embedded throughout. This wiring is not transparent. Therefore, ZTE shifts the wiring of the display part, which is placed above the camera, to the periphery, so that it has as little effect as possible on the image captured.
4. Optimizing the display where the camera is embedded
The display area above the camera has a lower resolution than the rest of the screen, and there is a gap between the pixels. To ensure that there is no discomfort between the camera part and the rest of the display when displaying video and other images, ZTE has optimized the placement of the pixels in this part of the display. In this area, the company worked especially closely with the OLED display manufacturer to make tweaks, and made many adjustments so that photos and other images would actually be displayed without any discomfort.
5. Software compensation
Even if the camera is embedded underneath the screen in this way and the display is finished so that it looks natural, the image is inevitably different from that of a typical front camera because the glass of the display is placed above the camera. So the engineers use software control to adjust contrast and mitigate the cloudy look. Incidentally, if you take a picture with the front camera on the AXON 20 5G or the Rakuten BIG, you have to wait 2-3 seconds before you can save it, but this is probably because of the software processing.
As you can see, the AXON 20 5G's camera-embedded display was made possible by combining multiple technologies. In addition, a fingerprint sensor, a proximity sensor, and a speaker are also embedded underneath the display, making it a complex structure. And not only that, but it also boasts high performance, with 90 Hz drive and a 10-bit display. The AXON 20 5G doesn't just have an "invisible front camera", it also has a next-generation display that uses the latest technology.
This article is based on an article from the Japanese edition of Engadget and was created using the translation tool Deepl. The Japanese edition of Engadget does not guarantee the accuracy or reliability of this article.