Stacked CMOS analysis (II): OPPO Find 5 camera depth mining
Stacked CMOS analysis (II): OPPO Find 5 camera depth mining

Previous article《 OPPO Find 5 Detailed Analysis of Stacked CMOS (I): From Sony 》The concepts of "backlight CMOS" and "Sony Exmor R CMOS" were discussed in, and today we will continue to introduce "stack CMOS" formally. Stacked CMOS, called "Stacked CMOS" in English, can also be translated as "Stacked CMOS". In fact, these concepts refer to the same thing.

Stacked CMOS was first released in late August this year, and its first application was on OPPO Find 5 just released a few days ago. Find 5 is the first product to take advantage of the crab, which pioneered the formal commercial use of stacked CMOS. At present, its real photo effect is unknown. Only in the sense of development, Find 5 is worth affirming.

1、 Stack CMOS and Sony Exmor R CMOS

At present, Sony is the only manufacturer with the capability of "stack CMOS" technology. In fact, it is also preparing for Sony's CMOS history mentioned above. As mentioned above, Sony's backlit CMOS brand name is "Exmor R CMOS". In the latest generation of stack CMOS, Sony renamed this part of products as "Exmor RS CMOS". The difference is that there is an additional letter "S", which is the abbreviation of "stack". In fact, it refers to stacked CMOS, namely stack CMOS.

Benefiting from the technical advantages, the stack type CMOS currently appearing in the market is actually Sony's "Exmor RS CMOS", and this one has no other place. Stacked CMOS is one of the future development directions of CMOS technology. I believe that other CMOS manufacturers will achieve this level of technology in the future. But now Sony has taken a big step ahead and its core technology value has been fully reflected.

2、 Principle and Characteristics of Exmor RS Stacked CMOS Sensor

In late August this year, Sony released the world's first new "stacked structure" image sensor, namely "Exmor RS CMOS". Exmor RS CMOS is characterized by high pixel, high performance and miniaturization.

The principle of Exmor RS CMOS is that it uses a chip with a signal processing circuit to replace the original supporting substrate of the back lit CMOS image sensor, and forms the pixel part of the back lit CMOS component by overlapping on the chip, thus realizing the process of forming a large number of pixel points on a small chip size. Since the pixel part and the circuit part are independent, the pixel part can be optimized for high image quality, and the circuit part can be optimized for high performance.

3、 Stack type CMOS depth guess adopted by Find 5

When Exmor RS CMOS was released, three models of products were launched: IMX135 (1/3.06 inch 13.13 million effective pixels), IMX134 (1/4 inch 8.08 million effective pixels), and ISX014 (built-in camera model processing performance, with 1/4 inch 8.08 million effective pixels). Corresponding to the above three stacked CMOS sensors, there are also three small autofocus imaging modules: IU135F3-Z, IU134F9-Z and IUS014F-Z. They are equipped with lens components with auto focus function, with 1.12 μ m pixel spacing, and can achieve ultra fresh resolution. Among them, IU135F3-Z adopts F2.2 super aperture lens and is equipped with 5 sets of 5 synthetic resin lenses.

To sum up, the parameters of IU135F3-Z are roughly 1/3.06 inch, 13.13 million effective pixels, F2.2 large aperture, and 5 lenses. Based on the OPPO official description of the Find 5 camera, we can basically determine that the Find 5 is equipped with IU135F3-Z module, and the sensor model is IMX135.

4、 How does the image quality of Exmor RS stack CMOS improve?

When we talk about the principle above, we can know that Exmor RS stack CMOS is smaller and more convenient for mobile products such as mobile phones. In addition, its image quality has also been improved. How can we do that?

Among the three released Exmor RS CMOS models, IMX135 and IMX134 are equipped with "RGBW encoding" technology and HDR (high dynamic video) shooting function to improve the shooting quality.

① RGBW encoding technology

The RGB W coding technology adds white pixels to the original red (R), green (G), and blue (B) RGB pixels, which improves the sensitivity and image quality, and can capture beautiful and clear images even in weak light environments.

Example of RGBW encoding technology: the picture taken is 10lux low illumination, the left is taken by the original back illuminated CMOS sensor, and the right is taken by the Exmor RS stack CMOS sensor

② HDR shooting function

HDR shooting function can set two exposure modes when shooting the same picture. Through proper signal processing, a wide range of high dynamic range images can be generated. Even when shooting with bright light, overexposure will not occur.

Example of HDR shooting function: the left side is the original backlight CMOS sensor shooting, and the right side is the Exmor RS stack CMOS sensor shooting

5、 Dig again: What is the price of Exmor RS stack CMOS?

The following prices are purely speculative.

The above figure is for reference only. It can be seen from it that the sample price of IU135F3-Z module equipped with Find 5 is about 8000 yen, which is also close to 600 yuan. Such a high price must surprise many people. Of course, this refers to the sample price. It is estimated that the manufacturer's price will be much lower when purchasing in batches. It is difficult to estimate the cost for the time being. It may be necessary to ask OPPO engineers.

6、 Final summary:

① Conceptual relationship cannot be mixed: the relationship between stacked CMOS and back illuminated CMOS

Stacking and reflection are two different things, and they are two irrelevant structural modes. Stack style is mainly used to reduce the size, and the image quality is also optimized; The back reflection is a design for improving the image quality. A CMOS can be used in a back lit or stack design alone or in both ways. For example, Exmor R CMOS is just a back lit design, while Exmor RS CMOS is based on back lit design, and then put the signal processing circuit chip behind to make a stack design, which has two design structures.

② The relationship between stack CMOS and the image quality of Find 5

Now? Find 5 It has not been officially launched yet. We saw the official photo samples at the press conference, but it is still impossible to make horizontal comparison with the mainstream models. The stack CMOS equipped with the Find 5 is the future and the direction of development, but it does not mean that the Find 5 will definitely beat the mainstream models when taking photos. Even if it is compared with the real machine in the future, it cannot explain how the stack CMOS works, because it is not only the CMOS sensor structure, but also the CMOS size, lens, algorithm optimization and other more in-depth factors that can improve the picture quality.

Take Find 5 for example, its CMOS size is 1/3.06 inch, while the current camera Nokia 808 pureview is 1/1.2 inch. Obviously, the sensor of Nokia 808 is not a little bit larger than that of Find 5. It can be determined that the CMOS of the 808 is not a stack design. If this design is adopted in the future, the CMOS can be larger and the imaging effect can be better based on the existing space.

The other is algorithm. Apple iPhone is a typical outstanding representative of algorithm. Thanks to this, although the iPhone 4S/5 camera parameters are not very prominent, the actual photo taking performance is among the best among many flagship models.

Related reading:

OPPO Find 5 Detailed Analysis of Stacked CMOS (I): From Sony

Against the sky! Find 5 uses a stacked CMOS sensor

About phone camera: pixels

Aikepu: composition structure of mobile camera

Why does iPhone 5 perform better in taking photos?

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