A book about CCD technology

CCD is the core component of CCD digital camera. Understanding the development history of CCD technology is helpful for us to deepen our understanding of digital cameras, which is of great significance for improving our shooting technology and purchasing a cost-effective digital camera.

Because Sony and Fuji's CCD do better, we will focus on their CCD technology development. If you are an IT practitioner or the boss of an IT manufacturer, after reading it, you should take a good look at what you should learn from Japanese IT companies. Why are there so many Sony fans and Fuji fans now? Is this just because their market is doing well? Is the sales channel well done? Learn from others' down-to-earth style, learn from others' strategic vision and learn from others' spirit of hard struggle!

Note: This article is of great reference value to experts who use digital cameras and digital video cameras or professionals related to this field.

1. Development of Sony CCD technology

Due to the complex production process of CCD, so far, only six manufacturers in the world, Sony, Fuji, Kodak, Philips, Panasonic and Sharp, can mass-produce CCD, and Sony is the most important supplier. Sony is the earliest manufacturer of CCD, and has been developing CCD since 1970s. Since the beginning of CCD production, the cumulative output has exceeded 654.38 billion pieces, and it has become the market leader of CCD with a market share of 50%. The following is a brief history of Sony CCD technology development.

1969, the American Bell Telephone Research Institute invented CCD. Is a magician who converts "light" information into "electricity" information. At that time, in Sony's development team, a young man named Yue was very interested in CCD and began to study CCD. But because this research is far from commercialization, the more intelligent it is, the more it can only be studied silently and alone. 1973, a discerning operator, Iwatani, then vice president of Sony, discovered more intelligent research and said with great excitement: "This should be the task completed by Sony's semiconductor department! Ok, we will cultivate this seedling! " At that time, only 64 pixels were used to draw a rough "S". However, there is a saying between rocks that makes Yue Zhi puzzled: "Make a camera with CCD. Our opponent is not an electrical appliance manufacturer, but a film manufacturer Eastman Kodak! " At that time, Sony had nothing to do with Kodak. Why is Kodak an opponent? Today, nearly 40 years later, when Sony launched an 8-megapixel F828 digital camera and entered the market, the mystery was finally revealed. Iwatani said, "The development of CCD should aim at surpassing the image quality of Kodak's film photos!"

Iwatani is a visionary operator. When Sony began to introduce transistors, Iwatani was in the front line. He personally visited the United States and sent back a technical report from the United States. With these reports, Sony's predecessor, Tokyo Communication Industry, produced transistors and grew into a world-class semiconductor manufacturer. At that time, CCD was just something in the laboratory, and no one thought it could become a commodity. Because according to the technical level at that time, it is generally believed that it is almost impossible to produce a CCD with more than 654.38+10,000 components perfectly on a single integrated block with large-scale integrated circuit technology. General enterprises withdraw from the research after discovering this situation. However, Iwatani doesn't think so. His conclusion is: "Because no one seized the opportunity, we had to do it!"

At that time, it was marginal learning, and the efforts to swallow water were hard to work. Besides, this is a very expensive study. It is said that Sony spent as much as 20 billion yen on CCD from the development stage to commercialization. Although only 3 billion yen was spent on the project research, 65.438+0.7 billion yen was invested in this area because the processing and manufacturing of CCD require a lot of proprietary technology, and the technology accumulation process is the most difficult to achieve mass production. Therefore, this project is impossible without the support of excellent operators. Iwatani was the president of Sony's American branch. After returning to Sony in Japan, he served as the vice president and director of Sony Central Research Institute. According to Muhara, head of Sony Development Group, "At the beginning of returning to China, Iwatani inspected all members of Academia Sinica. With the passage of time, his focus gradually shifted to the development of CCD. It has been noticed that half of his day is occupied by Yue Zhicheng, who is engaged in CCD research. 1973, 1 1 In June, CCD finally established a project and established a development team with Yuezhi as the core. "

With the support of the whole company, the development team overcame many difficulties and finally manufactured an integrated block that was considered "impossible" in March of 1978, and10000 components were installed on a circuit board. Later, it took two years to improve the image quality, and finally the world's first CCD color camera was built. On this basis, the commercialization of CCD camera is realized for the first time. At that time, the yield of CCD was very low, and only one piece was qualified every 100. Once the production line was fully loaded, only one piece could be produced. Someone joked: this is not a qualified rate, it is simply an incidence rate! Sony received an order for ANA 13 CCD cameras, and it took a whole year to produce the CCD integrated block.

1980 65438+ 10, Iwatani, who was promoted to the position of president, set a new goal for the development team: "to develop a camera with integrated video and audio recording using CCD technology". This is another struggle. The first 8 mm camera "CCD-V8" was finally born in 1985 with the joint efforts of the development team of CCD camera and ordinary camera. It has been 15 years since the beginning of CCD research and the production of the first 8 mm CCD camera.

From the development of CCD to the commercialization of digital cameras, it is only the beginning. There is still a long way to go to truly achieve the image quality comparable to that of optical cameras. Although the CCD originally used for digital cameras was converted from the special products for video recorders, the "pixel competition" soon appeared in the special CCD for digital cameras, and the CCD quality of still pictures was rapidly improved.

The following briefly introduces Sony's development in CCD sensor technology after entering the 1980s in chronological order:

1, with sensor (early 1980s)

HAD(HOLE-ACCUMULATION DIODE) sensor is a unique structure of Sony. A positive hole accumulation layer is added on the surface of N-type substrate, P-type and N+2 electrode. Due to the design of this positive hole accumulation layer, the common dark current problem on the sensor surface can be solved. In addition, a vertical tunnel is designed on the N-type substrate to allow electrons to pass through, which improves the aperture ratio, in other words, improves the sensitivity. In the early 1980s, Sony took the lead in using it in the line-style variable-speed electronic shutter products, which can obtain clear images even when shooting fast-moving objects.

2. On-chip microlens (late 1980s)

In the late 1980s, due to the shrinking of each pixel in CCD, the light receiving area will be reduced and the sensitivity will be lower. In order to improve this problem, Sony installed a special micro lens in front of each photodiode, which can increase the photosensitive area of CCD. Therefore, after using this microlens, the photosensitive area is not determined by the opening area of the sensor, but by the surface area of this microlens. Therefore, the aperture ratio is improved in specification, and the brightness is also greatly improved.

3. Super HadCCD (mid-1990s)

Since the mid-1990s, CCD technology has developed rapidly. At the same time, the unit area of CCD is getting smaller and smaller. Due to the limitation of CCD area, the microlens technology developed by Sony 1989 has been unable to improve the brightness of CCD. If the amplification factor of the internal amplifier of CCD module is increased, the noise will be increased at the same time, and the imaging quality will be greatly affected. In order to solve this problem, Sony improved the technology of micro lens used in CCD before, which improved the utilization rate of light, and developed a technology to optimize the lens shape, namely Sony SUPER HAD CCD technology. The improvement of this technology has further improved the sensory performance of Sony CCD.

4. New structure CCD( 1998)

With the increasing f value of the optical lens aperture of the camera, more and more oblique light enters the camera, but more holmium light cannot 100% incident on the CCD sensor, thus limiting the sensitivity of the CCD. 1998, Sony noticed the negative impact of this problem on imaging quality and conducted technical public relations. In order to improve this problem, they added an inner lens between the color filter and the light shielding film. After adding this layer of lens, the internal optical path can be improved, so that oblique light can also be completely focused on the CCD photoreceptor, and at the same time, the insulating layer between the silicon substrate and the electrode is thinned, so that the signal that will cause vertical CCD image noise will not enter, and the smear characteristics are improved.

5.EXVIEW has CCD( 1999).

Infrared light with a longer wavelength than visible light will be photoelectric converted in semiconductor silicon wafer. But so far, CCD can not effectively collect these photoelectric converted charges into the sensor. Therefore, Sony's newly developed "EXVIEW HAD CCD" technology in 1999 can effectively convert the near-infrared light that has not been effectively used before into image data for utilization. So that the visible light range is expanded to infrared light, and the brightness can be greatly improved. When using "EXVIEW HAD CCD" module, you can get high-brightness photos in dark environment. Moreover, in the process of photoelectric conversion in the deep layer of silicon wafer, the trailing components leaked to the vertical CCD can also be collected in the sensor, so the noise affecting the image quality will be greatly reduced.

Since CCD production, Sony's production capacity has exceeded 654.38+0 billion. In the future, Sony will actively reduce the power consumption of products, reduce the complexity of driving circuits, reduce the number of IC pins, reduce the burden of electronic products on the earth's ecological environment, and develop and design new CCD components. Under the trend of more and more diversified applications of CCD, the basic characteristics of miniaturization and high pixel of CCD should be strengthened to provide more attractive and high value-added products to meet the requirements of users.

6. Four-color filter technology (July 2003)

On July 16, 2003, Sony officially announced that it would adopt a brand-new four-color filter technology on its brand-new consumer-grade CCD products. Now Sony's F828 digital camera with 8 million pixels is designed and produced with this brand-new CCD.

We know that the traditional light perception is nothing more than red, green, blue and RGB. The CCD/CMOS light sensing unit used in digital camera adopts the principle of color filter, and each pixel senses different colors, and then recombines these colors into an effective pixel. The brand-new four-color filter standard is called RGBE. Compared with RGB, the brand-new E is considered by Sony as a bright blue standard, where E is the abbreviation of the English word Emerald (it should be considered turquoise). Sony believes that the new four-color filter technology will be closer to the natural color recognition standard of human eyes, thus achieving a more realistic color reproduction standard. While releasing RGBE technology, Sony also released a new image processing module to match the new four-color filter CCD module. With the brand-new RGBE technology and brand-new image processing module, the new generation RGBE CCD module can reduce the error of digital camera in color reproduction by at least half, and the restoration effect of digital camera in blue, green and red will be enhanced at the same time. In addition, the brand-new image processing unit will be optimized in terms of energy consumption, which can save at least 30% energy consumption compared with the image processing module using RGB technology before. Of course, the brand-new image processing unit will effectively improve the shooting speed and playback speed of digital cameras. Sony believes that the new RGBE module design will improve the performance of existing digital camera products as a whole.

Second, the development of Fuji super CCD

Although Fuji is not as strong as Sony in CCD research and development, and its CCD research and development process is not as long as Sony's, its super CCD is very unique.

Fuji's super CCD technology was developed in 1999. Today, most digital cameras on the market use area CCD as sensor. The disadvantage of this CCD is that the pixel area is contradictory to CCD, because to improve the image quality, it is necessary to increase the pixels of CCD. Therefore, in the case of a certain CCD size, increasing pixels means reducing photodiodes in pixels. We know that the smaller the area of a unit pixel, the lower its photosensitivity, the lower its signal-to-noise ratio and the narrower its dynamic range. Therefore, this method cannot improve the resolution indefinitely. Therefore, if the resolution is blindly improved without increasing the CCD area, it will only lead to the deterioration of image quality. However, in order to increase the number of CCD pixels while maintaining the existing image quality, it is necessary to increase the total area of CCD on the basis of maintaining at least the unit pixel area. Up to now, it is still difficult to manufacture larger CCD, and the yield is relatively low, so the cost has not been reduced. This contradiction is difficult for CCD to overcome. 1999, fuji company noticed this. In order to solve this problem, they developed the first generation super CCD. Super CCD adopts octagonal photodiode and honeycomb pixel arrangement, which greatly improves the spatial effectiveness of photodiode in each pixel unit. After the pixels are arranged in a honeycomb shape at a 45-degree angle, the control signal path is cancelled, and the space saved enables the photodiode to be amplified, while the octagonal photodiode can absorb light more effectively than the rectangular photodiode because it is closer to the circular shape of the microlens. The increase of photodiode and the improvement of light absorption efficiency increase the charge absorbed by each pixel, thus improving the sensitivity and signal-to-noise ratio of CCD. Therefore, compared with the traditional CCD with the same number of pixels, it has higher sensitivity, higher signal-to-noise ratio and wider dynamic range.

In 200 1 year, the first generation of super CCD won the "Walter Kosonoki Award" for excellent research results of solid-state camera components awarded to CCD;

The second generation super CCD was born in 200 1. Compared with the first generation super CCD, it has much higher pixel number, much lower noise and higher image definition. This technology has been highly praised and made a breakthrough in image quality and detail.

The third generation super CCD was born in 2002. Its characteristic is to realize ISO 1600, shoot VGA movies at the speed of 30 frames per second, and adopt new image processing algorithm and chip technology.

The fourth generation super CCD was born in 2003. At the beginning of 2003, in Britain, Fuji released the contents of super CCD SR/HR technology at a press conference, which is also the fourth generation derivative product of super CCD technology. At the beginning of March, 2003, at the PMA 2003 exhibition held in Las Vegas, USA, Fuji presented its digital camera-Finepix F700 with the fourth generation super CCD technology. Its appearance announced that Fuji's fourth-generation super CCD technology officially entered the stage of popularization and application.

SR of the brand-new super CCD SR technology means "super dynamic range", which can improve the dynamic expansion effect twice or even more than the existing traditional CCD technology. The concept of super CCD SR is that there are two photodiodes on each microlens on the surface of CCD sensor. One of them is responsible for capturing signals under sensitive black and normal light standards, and the other is responsible for capturing some signals in high brightness areas. The optical signals captured by two photodiodes are synthesized into a complete photo by the camera, which provides an amazing dynamic response beyond the second-order aperture of ordinary CCD.

SupercCCD SR technology extends the dynamic range of CCD to the level of ordinary traditional negative film, which means that digital cameras equipped with Fuji SupercCCD SR technology can take clear photos in extremely weak or extremely strong light environment. Fuji believes that the existing negative technology is realized by multi-layer exposure with different standards, and it can also provide a very wide dynamic expansion range. SupercCCD SR technology is designed for this effect. It provides different exposure standards through two photodiodes by imitating the negative exposure mode.

Fuji's super CCD technology has been mixed since its birth. In fact, super CCD can effectively improve the imaging pixels, but it has been doubted and belittled by professionals in detail performance and imaging effect. Fuji's brand-new Super CCD SR technology is a modification and supplement to the existing Super CCD technology, which can effectively improve the imaging pixels, optimize the details and imaging quality, and truly meet the increasingly critical needs of consumers.