Technology

Collecting the imperial three: all under-screen cameras, but all different

Collecting the imperial three: all under-screen cameras, but all different

The release of the ZTE Axon 40 Ultra a few days ago marked the launch of three major domestic OLED suppliers, Huaxing Optoelectronics, Visionox, and BOE, all of which have launched OLED panels serving under-screen cameras, and the three models they have recently landed in mass production are Xiaomi's MIX 4, Red Magic 7 Pro, and ZTE's Axon 40 Ultra.

Collecting the imperial three: all under-screen cameras, but all different

▲ Xiaomi MIX 4, Red Devil 7 Pro, ZTE Axon 40 Ultra (left to right)

Just these three models in hand, let's take these three models as a representative, a peek at the three panel suppliers Huaxing Optoelectronics, Visionox, BOE in the level of under-screen camera OLED technology.

Collecting the imperial three: all under-screen cameras, but all different

First, the Xiaomi MIX 4 with Huaxing Optoelectronics was released in August 2021, one of the earliest machines released by all three. The OLED panel uses a diamond-like arrangement called "pearl arrangement" by Huaxing Optoelectronics, and the sub-pixel diagram captured by the microscope camera in our WHYLAB lab is as follows.

Collecting the imperial three: all under-screen cameras, but all different

▲ Huaxing Optoelectronics / Xiaomi MIX 4

The top right is the pearl arrangement of sub-pixels in the general area, and the bottom left is the "micro-drill" arrangement in the under-screen camera transmissive area. The actual arrangement has the same density as the general area, mainly reducing the area of sub-pixels while increasing pixel brightness to ensure consistency of display, while redesigning the circuit arrangement and using wave leads to enhance the transparency of the panel.

The Red Devil 7 Pro, released in February, is the first gaming/gaming phone on the market to use an under-screen camera. The OLED panel is provided by Visionox, and the most important feature is the use of Visionox's self-developed "tripod arrangement" - according to Visionox, the so-called "tripod arrangement" sub-pixel combination is isosceles trapezoid, which is similar to the side view of a "tripod" in China's Bronze Age, hence the name.

Collecting the imperial three: all under-screen cameras, but all different

The sub-pixel diagrams captured by the microscope are as follows: the left side is the light-transmitting area of the camera, and the right side is the normal pixel, and both are "tripod arrangement" with the same pixel density, the obvious difference is that the area of the single pixel on the left side is smaller.

Collecting the imperial three: all under-screen cameras, but all different

▲ Visionox / Red Devil 7 Pro

It is said that this "tripod arrangement" allows for higher customization of sub-pixels, increasing the margin of the process and providing more space for the design of the under-screen camera. On this basis, the "multi-drive ACE circuit" technology optimizes the circuit density in the transparent area of the camera and the "wave-type electrode" reduces diffraction to enhance the light transmission in the under-screen camera area.

As for the recently announced ZTE Axon 40 Ultra panel provided by BOE, it is the latest OLED solution for under-screen cameras at the consumer end. The sub-pixel image captured by the microscope is shown below, with the sub-pixels in the transparent area at the top (to the left) and the sub-pixels in the normal area at the bottom, both using the BOE diamond-like arrangement called "Blue Diamond Arrangement".

Collecting the imperial three: all under-screen cameras, but all different

▲ BOE / ZTE Axon 40 Ultra

In addition to what distributed transparent circuitry and UDC Pro exclusive display chip, it is more advanced than its two predecessors in using a drive-by-one independent pixel driver technology that helps eliminate the bad jagged effect of the previous under-screen camera transparent area.

What about actual performance?

Collecting the imperial three: all under-screen cameras, but all different

▲ Xiaomi MIX 4 (Huaxing Optoelectronics), Red Devil 7 Pro (Visionox), ZTE Axon 40 Ultra (BOE)

Here I made a diagram, put a # sign in the camera area, look closely at the camera area can easily find the difference between the three.

Collecting the imperial three: all under-screen cameras, but all different

▲ Xiaomi MIX 4 (Huaxing Optoelectronics), Red Devil 7 Pro (Visionox), ZTE Axon 40 Ultra (BOE)

The jaggedness of the under-screen camera area is the most obvious in Visionox (Red Devil 7 Pro), where the display resolution looks less high and the sense of cut is more obvious; while the anti-aliasing effect of Huaxing Optoelectronics (Xiaomi MIX4) is significantly better than Visionox, where the slight jaggedness can only be detected with the naked eye; as for BOE (ZTE Axon 40 Ultra), the anti-aliasing effect is further than that of Huaxing Optoelectronics. This shows that the independent pixel drive technology does work -- after all, the independent pixel drive can precisely control the display of a single pixel, while Visionox and Huaxing Optoelectronics drive multiple pixels, and the hardware cannot do the detailed control of a single pixel, resulting in the jaggedness of #; and Huaxing The precision of optical control is higher than that of Visionox, so the jagged effect of the former is weaker than that of the latter.

Collecting the imperial three: all under-screen cameras, but all different

▲ Xiaomi MIX 4 (Huaxing Optoelectronics), Red Devil 7 Pro (Visionox), ZTE Axon 40 Ultra (BOE)

Manufacturers have put in all their efforts to hide the front-facing camera, but all three can still be found in the under-screen camera area when viewed at a specific angle under bright light -- Rectangular for Visionox, larger round for Huaxing, and smaller round for BOE, and better hidden for Huaxing and BOE.

Under-screen camera OLED is a "paradoxical" product: on the one hand, manufacturers try to hide the front camera as much as possible, so as not to destroy the integration of the whole screen, not to compromise the display effect of this small area; on the other hand, they want to ensure the image quality of the front camera under the premise of the existence of this "veil" - in order to achieve a balance between the two, manufacturers have made every effort, in addition to OLED sub-pixels, circuitry, drivers and other components of hardware optimization, algorithm optimization is also indispensable.

Collecting the imperial three: all under-screen cameras, but all different

Huaxing's Xiaomi MIX 4 uses a 20-megapixel Samsung S5K3T2 front camera with 1.6μm fusion large pixels, paired with deep learning-based enhancement algorithms to optimize colors and improve photo details; Vixen's Red Devil 7 Pro uses a 16-megapixel OV16E1Q front camera, which does not officially reveal its selfie optimization algorithm; BOE's ZTE Axon 40 Ultra's 16-megapixel, with 2.24μm fused large pixels, also with deep learning-based algorithm calibration, multi-frame RAW fusion technology to improve image quality.

As for how effective, look at the sample comparison, and let you choose the best one in addition to the reference model.

Collecting the imperial three: all under-screen cameras, but all different

▲ Reference model (non-under-screen camera), Xiaomi MIX 4 (Huaxing Photoelectric)

Collecting the imperial three: all under-screen cameras, but all different

▲ Red Devil 7 Pro (Vixen), ZTE Axon 40 Ultra (BOE)

Overall, we can see that the usability of under-screen cameras in terms of display has been very high nowadays, and basically can't pick too much fault in itself. A new technology in the early stages of popularization, it is always the later in the technically more mature, such as BOE used a drive a separate pixel drive technology, so that the display effect of the under-screen camera area further close to the ordinary area, greatly reducing the jagged effect, and recently there is news that Huaxing Optoelectronics will also mass production of a similar drive a separate pixel drive technology under-screen camera panel, it is said that there is a more recent technical Progress.

The biggest problem is the light intake of the front camera and the light diffraction problem caused by OLED, there is always a "veil" between the camera and the outside, and what manufacturers need to solve in the future is to make it increasingly "thin" in the case of this "veil" must exist.