Application of CMOS image sensor in security camera
Source:Shenzhen Kai Mo Rui Electronic Technology Co. LTD2020-05-08
With the rise of various consumer electronics, image sensors have become one of the dazzling star products in the semiconductor industry. Among image sensors, CCD sensors and the emerging growth of CMOS Sensors have gradually found their own application markets, hoping to become the market Mainstream technology. Compared with CCD sensors, CMOS image sensors have the disadvantages of low sensitivity and high signal-to-noise ratio, but they still have the advantages of low power consumption and low cost.
According to the analysis of the global Image Sensor (image sensor) IC component market, the global Image Sensor component application market was worth US$710 million in 2010. After the impact of the financial turmoil, it continues to show a positive growth trend. TRI estimates that the size of the Image Sensor market in 2012 will be close to US$850 million; the Image Sensor market accounts for a higher proportion of CMOS Sensor, with an average of about 90%.
According to the analysis of the CMOS Sensor market size, the overall market size of CMOS Sensor components in 2010 was US$630 million, accounting for 89% of the overall ImageSensor market, and the overall market trend maintained an average of 90% range. With the high penetration rate of various consumer electronics devices, the future growth rate will slow down and enter the mature stage of industrial growth. TRI estimates that the annual growth rate of CMOS Sensor in 2011 is 13%. In the future, it will pursue the technology pixel and Improvements in manufacturing costs.
CMOS Sensor is an important image sensor application component in the camera module application market. Among them, communication electronics products account for a high proportion of applications, accounting for 70% of the overall CMOS Sensor market. The main applications of the CMOS Sensor market include security systems, automotive systems, and PCs. Related peripheral applications, digital cameras, etc. The tablet PC market driven by IPad is a fast growing application market for CMOS Sensor.
The application market of security cameras accounts for 10% of the image sensor market value. In the past, CCDs were mostly used as image sensors. In recent years, the performance of CMOSSensor has been continuously improved, and it has begun to enter the market that has long been exclusive to CCD Sensors, mainly focusing on lower-priced security cameras.
CCD and CMOS technical characteristics
The technical characteristics of CCD and CMOS mainly lie in the imaging process, integration, power consumption, performance indicators, etc.
imaging process
CCD and CMOS use the same photosensitive material, so the basic principle of generating electrons after receiving light is the same, but the reading process is different: CCD is transferred in a frame or line mode under the cooperation of a synchronization signal and a clock signal. The entire circuit is very complicated. The output rate is slow; CMOS reads signals in a similar manner to DRAM, with simple circuits and high read rates.
Integration
The CCD readout circuit with special manufacturing process is more complicated. It is difficult to integrate A/D conversion, signal processing, automatic gain control, precision amplification and storage functions on a single chip. Generally, multiple chips are required to be combined to achieve it, and one Multi-channel non-standard power supply voltage. With the aid of a large-scale integrated manufacturing process, CMOS image sensors can easily integrate the above-mentioned functions on a single chip. Most CMOS image sensors have both analog and digital output signals.
Power, power consumption and volume
CCD needs a variety of power supplies, power consumption is relatively large, and the volume is relatively large. CMOS only needs a single power supply (3V~5V) to supply power, its power consumption is equivalent to 1/10 of CCD, and highly integrated CMOS chips can be made quite small.
Performance
CCD technology has been quite mature, and CMOS is in a period of vigorous development, although the current high-end CMOS image quality is temporarily not as good as CCD, but some indicators (such as transmission rate, etc.) have exceeded CCD. Due to the many advantages of CMOS, many institutions at home and abroad have developed many products using CMOS image sensors.
CMOS sensor key technology breakthrough
The technological development of CMOS sensor follows Moore's law to develop rapidly, especially in the past few years, driven by market demand, breakthroughs have been made in key technologies. Regarding issues such as the illumination and noise of CMOS that users are concerned about, in fact, the signal-to-noise ratio of CMOS under visible light is much higher than that of CCD. On the one hand, with the continuous improvement of major international CMOS manufacturers, CMOS continues to catch up in terms of imaging transparency and color reproduction capabilities of real objects. The sensitivity enhancement technology has been developed to increase the aperture ratio through the use of large-size sensors.
This is a direct way to improve the CMOS sensitivity. Even in terms of noise control, some companies directly integrate specialized noise detection algorithms into the control logic of CMOS image sensors. Through this technology, fixed noise can be successfully eliminated. What's more, the price of CMOS is much lower than that of CCD equipment. On the other hand, a variety of technological innovations are used in ISP, such as denoising technology to improve the noise problem of CMOS.
In addition, in terms of technology, every time a CCD increases by 1 million pixels, its production line needs to be modified, and the cost of R&D and production is relatively high. If the CCD size is still maintained at 2/3 inches, the gap of the unit electrode will be limited to 0.4 microns, which will lead to a significant increase in the rate of damage and production costs in manufacturing.
With the continuous efforts of major manufacturers, new CMOS devices are constantly being introduced, and high dynamic range CMOS devices have appeared. This technology eliminates the need for shutter, iris, automatic gain control and gamma correction. In addition, due to the inherent plasticity of CMOS, large-scale CMOS photoreceptors with high resolution pixels can be made without increasing the cost. Compared with the stagnation of CCD, CMOS has shown vigorous vitality as a new thing. CMOS image sensors are developing into a diversified market segment with high resolution, high dynamic range, high sensitivity, digitization, and multifunction. With the continuous progress of CMOS image sensor technology, the application of CMOS sensors in security cameras will continue to increase.
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