Camera CMOS and CCD battle

The CMOS and CCD debates have been going on for a long time. The photoreceptors are the core of imaging technology and the most critical technology. The problem of out-of-stock commuting on the 139-inch CMOS chip has caused headaches for SMEs and has become a hot topic in the industry. In recent years, CCD and CMOS have been competing for the market share of the photographic sensor. In the recent 139-chip turmoil, the competition between the CCD and CMOS has entered the white-hot phase: CCD chips continue to reduce prices, and CMOS chips continue to increase prices. Someone has asserted that the era of CCD is nearing completion and CMOS will be very popular. Whether or not CCDs will be terminated by CMOS as some people have said, we think that we must also look at the next step in the development of the market.

The advantages and disadvantages of CCD and CMOS, we can from the technical point of view to compare the main differences between the two:

(a) Information reading method The charge information stored in different CCD sensors needs to be read after the one-bit transfer under the control of the synchronization signal. The charge information transfer and read output require a clock control circuit and three different sets of power phases. With the entire circuit is more complex. The CMOS sensor directly generates a current (or voltage) signal after photoelectric conversion, and the signal reading is very simple.

(b) Velocity difference The CCD sensor needs to output information one bit at a time in the unit of synchronization under the control of the synchronous clock, and the speed is relatively slow; while the CMOS sensor can take out the optical signal while collecting the optical signal, it can also process the signals simultaneously. The image information of the unit is much faster than the CCD.

(c) Power supply and power consumption Most of the CCD sensor charge couplers require three sets of power supplies for power consumption. The CMOS sensor requires only one power supply and consumes only a small amount of power. It is only 1/8 of the CCD charge coupler. To 1/10, CMOS photoelectric sensors have great advantages in energy saving.

(d) Image quality CCD sensor production technology started earlier and the technology is relatively mature. Using PN and silica isolation layers to isolate noise, the imaging quality has certain advantages over CMOS sensors. Due to the high degree of integration of CMOS sensors, the distance between the photoelectric sensing elements and the circuit is very close, and the light and electromagnetic interference between them are more serious, and the noise has a great influence on the image quality. The CCD and CMOS sensors have different internal structures on the "internal structure" and "external junction" (the structure of the sensor itself). The imaging points of the CCD are arranged in an X-Y matrix, and each imaging point consists of a photodiode and its control. The composition of a nearby charge storage area. Photodiodes convert light (photons) into charges (electrons), and the amount of electrons collected is directly proportional to the intensity of the light. As these charges are read, each row of data is moved into a buffer in the vertical charge transfer direction. The charge information for each row is read continuously and sensed by the charge/voltage converter and amplifier. This structure produces images with low noise and high performance. However, the production of CCDs requires the use of clock signals and biasing techniques. Therefore, the entire structure is complicated, increasing the power consumption and increasing the cost.

COMS1089 and Magnesium 139 make COMS shine

Last year, Haikang Dahua launched the camera of PC1089COMS photosensitive element with South Korea's Paierer, and the conventional CCD chip suffered a heavy blow. PC1089 quickly occupied some of the market due to its price advantage and effect. When the 1089 chip sales are in full swing, the authoritative boss of the COMS MT9V139 put into the market, the effect of testing better than 1089, and the price of both are similar, so since the birth of magnesium 139 board machine, with high definition, high cost performance The market is widely sought after.

Magnium Optoelectronics (MT9V139) is a high-sensitivity image sensor solution. The sensor uses a fully integrated single-chip system chip, can provide excellent low-light performance, minimum illumination is 0.01LUX, beyond the expected demand of people on the same level of CCD sensors, also has excellent near infrared in night vision environment (NIR) response performance, and the chip is widely used in CCTV cameras, surveillance cameras, network cameras, car rearview camera, button camera and so on.

For a long time, with the batch use of COMS, more and more people have seen the defects of COMS, mainly reflected in the need to install IR-CUT to reflect the effect. IR-CUT is also a big fault, and many companies suffer. In addition, the life of COMS is still to be tested and there are uncertainties. In spite of this, the advent of the PC1089 and the Micron 139 still made the COMS a limelight, once reaching a high market share, resulting in a large number of CCD manufacturers cut production, the CCD market continues to cut prices, Japan's Sony Corporation is even more costly.

Magnesium 139 out of stock is a normal market response

139. The shortage of chips is mainly due to the phenomenon of supply exceeding demand caused by the temporary unsatisfactory output of the market, which is a normal market reaction. As the market has 139 chip replacement products, 139 chip prices have limited space. The 139 chip is mainly used in low-end and mid-range cameras. Due to its fine picture quality, less noise, low illumination, and low price, the chip is a suitable replacement for CCDs. Some camera manufacturers gradually adopted the chip. The large number of SMEs demanded a shortage of 139 chips, causing some companies to block purchases. The 139 chip, as the current leader, inevitably has its own drawbacks: the magnesium light 139 uses a 1/4-inch sensor. Compared to the 1/3-inch sensor, the size of the 1/4-inch sensor is 1/3 of the image width. The width is wide; and the height of the Magnitude 139 chip is too low, resulting in poor focusing of the lens with F1.6, 1.4, because the 139 sensor is too low and the lens requirements are relatively high.

Therefore, for many companies, the COMS chip has its advantages, but the defects of the COMS will certainly reserve a place for the development of the CCD, and the CCD chip will not end with this. In the face of the 139 chip shortage, enterprises should not be left unanswered, but should look for suitable alternative chip solutions, or actively upgrade the relevant technology.

COMS and CCD competition to promote technology upgrade

It is undeniable that the emergence of COMS has changed the situation of the CCD exclusive market, and has brought a severe test for the development of CCD. At the same time, such contests and competitions have also prompted the industry to innovate continuously, and technology has been continuously upgraded, bringing new vitality to the development of the industry.

Compared with the CCD, the advantages of the new CMOS chip are self-evident, in addition to low illumination, noise, CMOS sensor can directly output digital information, to avoid the A/D conversion data loss, while progressive scan CMOS can also Effectively avoids problems such as motion blur and tearing when interlaced. Therefore, the CMOS picture is more delicate and moving than the CCD.

With the large-scale application of high-definition network monitoring to CMOS, many people have questioned and worried about the future of CCD. However, from a technical point of view, CCD sensors still hold a certain share in network surveillance cameras, especially in analog cameras, due to their greater photosensitivity, and they have a very strong appeal. At present, it seems that CCD has an irreplaceable role in improving the wide dynamic efficiency of video processing. Therefore, although CMOS has gradually occupied more than half of the network monitoring market, the competition between CCD and CMOS will continue fiercely and will promote continuous upgrading of various technologies in future applications.

Whether CCD or CMOS has its own advantages and disadvantages, existence is a necessity. The contest between CCD and CMOS may be a long-term topic, and it will be difficult to determine in a short period of time. The contest between the two will surely further promote the industry's technology. Upgrade to promote the continuous development of the industry.