[ Huaqiang Security Network News ] It is understood that there are two forces in the surveillance market, one is CCD surveillance cameras, the other is CMOS surveillance cameras, they all have a strong market share, currently on the market, these two products are each other Fighting, like relying on one's own power to occupy more markets. So, how much do we know about their brothers? Today we will let the CCD surveillance camera PKCMOS surveillance camera. 
Sensitivity The biggest difference between CCD surveillance cameras and CMOS surveillance cameras is their sensitivity. CMOS sensors are typically 10 times less sensitive than CCD sensors due to differences in materials. The human eye can see the target below 1Lux illumination (full moon night). The CCD sensor can usually see slightly better than the human eye. It can see the target below 0.1~3Lux illumination, which is 3 to 10 of CMOS sensor sensitivity. Times.
The sensitivity of CMOS sensors is generally in the range of 6 to 15 Lux. CMOS sensors have a fixed noise 10 times higher than CCD sensors. The fixed pattern noise always stays on the screen as if it is a pattern, because the CMOS sensor is basically below 10Lux. It is used, so CCD sensors are used in surveillance cameras at important monitoring points such as industrial sites and high-end clubs. CMOS sensors are typically used in very low-end household products. In the market, surveillance cameras for CCD materials are much more expensive than surveillance cameras for CMOS materials, and they have been strictly distinguished in terms of price.
ACD is also very important <br> So, what caused the early CMOS to be less sensitive than CCD in sensitivity, we have to start from its structure.
The first difference between CCD and CMOS is that the photosensitive unit, that is, the pixel structure is different. In addition to the photodiode, the former photosensitive element includes a memory cell for controlling adjacent charges, and the photodiode occupies most of the area. The composition of the CMOS sensor is complicated. In addition to the photodiode at the core, it also includes an amplifier and an analog-to-digital conversion circuit. Each imaging point is formed as a photodiode and three transistors, and the area occupied by the photodiode is only A small part of the entire component.
Compared with the CMOS sensor, the effective photosensitive area of ​​the CCD sensor is large, and it can receive a strong optical signal under the same conditions, and the corresponding output electrical signal is also stronger; in terms of the output result, it is captured by the CMOS sensor. The image content is not as rich as the CCD sensor, the sharpness is poor, the image details are lost, and the noise is obvious. This is why early CMOS sensors are mostly inferior to CCDs.
However, with the development of technology, the emerging CMOS has been greatly improved in sensitivity. In the case of price advantage, it has begun to challenge the high-end market of CCD by changing its own shortcomings.
The difference in ADC position and number The second difference between CCD and CMOS is the difference in the position and number of ADCs (analog-to-digital converters). Each pixel of the CCD corresponds to only one ADC. Each time the photosensitive element is exposed, the pixel transfer processing is performed after the shutter is closed, and the control circuit sequentially transmits the "buffer" in a serial manner, and the output is guided by the bottom line. The amplifier to the CCD is amplified and then connected to the ADC output. In contrast, in the CMOS design, an ADC is connected next to each pixel, and the signal is directly amplified and converted into a digital signal.
It is also because of this difference that the signal of each photosensitive element in the CCD sensor can form a unified output. After the output data is uniformly processed by the amplifier, the electrical signal intensity of each image point is increased by the same amplitude; Each of the photosensitive elements carries an ADC, and there is no guarantee that the magnification of each image point is strictly uniform, so that the enlarged image data cannot restore the original appearance of the object. Finally, the output is reflected in the inevitable noise in the image, and the image quality and noise resistance are much lower than those of the CCD sensor.
So, is it true that CMOS vs. CCD is completely at a disadvantage? The answer is no.
Different CCD cameras and CMOS cameras that collect signals have great differences in signal acquisition. The former collects analog signals and distinguishes them by line number. The latter collects digital signals by pixel. Based on this basis, the surveillance cameras transmitted through the network are all CMOS lenses, while the traditional analog surveillance cameras use CCD as the photosensitive elements. At present, although the network camera is "small in qualification", the future development trend of surveillance cameras will definitely develop into a network, which gives CMOS great development prospects.
Moreover, due to the difference in construction, CMOS is more favorable in price than CCD, and is not as complicated as CCD in the manufacturing process. Together with high technology, the up-and-coming CMOS is not sensitive to the current CCD in terms of sensitization and imaging. Therefore, the prospects for CMOS development are great. As far as the products on the market are concerned, the advantage of the CCD camera is that the nighttime sensitivity is good, but the CMOS camera can obtain high-definition images of more than 1 million pixels, which is unmatched by the CCD camera. From this, it can be concluded that CCD cameras and CMOS cameras are currently in the industry.
to sum up:
CCD and CMOS are twin brothers in the field of video surveillance like Gemini. As far as the current market situation is concerned, the two can be described as different. However, with the development of surveillance cameras, in addition to the two advantages of price and manufacturing process, CMOS in the future will be able to stand out in the field of video surveillance.
The sensitivity of CMOS sensors is generally in the range of 6 to 15 Lux. CMOS sensors have a fixed noise 10 times higher than CCD sensors. The fixed pattern noise always stays on the screen as if it is a pattern, because the CMOS sensor is basically below 10Lux. It is used, so CCD sensors are used in surveillance cameras at important monitoring points such as industrial sites and high-end clubs. CMOS sensors are typically used in very low-end household products. In the market, surveillance cameras for CCD materials are much more expensive than surveillance cameras for CMOS materials, and they have been strictly distinguished in terms of price.
ACD is also very important <br> So, what caused the early CMOS to be less sensitive than CCD in sensitivity, we have to start from its structure.
The first difference between CCD and CMOS is that the photosensitive unit, that is, the pixel structure is different. In addition to the photodiode, the former photosensitive element includes a memory cell for controlling adjacent charges, and the photodiode occupies most of the area. The composition of the CMOS sensor is complicated. In addition to the photodiode at the core, it also includes an amplifier and an analog-to-digital conversion circuit. Each imaging point is formed as a photodiode and three transistors, and the area occupied by the photodiode is only A small part of the entire component.
Compared with the CMOS sensor, the effective photosensitive area of ​​the CCD sensor is large, and it can receive a strong optical signal under the same conditions, and the corresponding output electrical signal is also stronger; in terms of the output result, it is captured by the CMOS sensor. The image content is not as rich as the CCD sensor, the sharpness is poor, the image details are lost, and the noise is obvious. This is why early CMOS sensors are mostly inferior to CCDs.
However, with the development of technology, the emerging CMOS has been greatly improved in sensitivity. In the case of price advantage, it has begun to challenge the high-end market of CCD by changing its own shortcomings.
The difference in ADC position and number The second difference between CCD and CMOS is the difference in the position and number of ADCs (analog-to-digital converters). Each pixel of the CCD corresponds to only one ADC. Each time the photosensitive element is exposed, the pixel transfer processing is performed after the shutter is closed, and the control circuit sequentially transmits the "buffer" in a serial manner, and the output is guided by the bottom line. The amplifier to the CCD is amplified and then connected to the ADC output. In contrast, in the CMOS design, an ADC is connected next to each pixel, and the signal is directly amplified and converted into a digital signal.
It is also because of this difference that the signal of each photosensitive element in the CCD sensor can form a unified output. After the output data is uniformly processed by the amplifier, the electrical signal intensity of each image point is increased by the same amplitude; Each of the photosensitive elements carries an ADC, and there is no guarantee that the magnification of each image point is strictly uniform, so that the enlarged image data cannot restore the original appearance of the object. Finally, the output is reflected in the inevitable noise in the image, and the image quality and noise resistance are much lower than those of the CCD sensor.
So, is it true that CMOS vs. CCD is completely at a disadvantage? The answer is no.
Different CCD cameras and CMOS cameras that collect signals have great differences in signal acquisition. The former collects analog signals and distinguishes them by line number. The latter collects digital signals by pixel. Based on this basis, the surveillance cameras transmitted through the network are all CMOS lenses, while the traditional analog surveillance cameras use CCD as the photosensitive elements. At present, although the network camera is "small in qualification", the future development trend of surveillance cameras will definitely develop into a network, which gives CMOS great development prospects.
Moreover, due to the difference in construction, CMOS is more favorable in price than CCD, and is not as complicated as CCD in the manufacturing process. Together with high technology, the up-and-coming CMOS is not sensitive to the current CCD in terms of sensitization and imaging. Therefore, the prospects for CMOS development are great. As far as the products on the market are concerned, the advantage of the CCD camera is that the nighttime sensitivity is good, but the CMOS camera can obtain high-definition images of more than 1 million pixels, which is unmatched by the CCD camera. From this, it can be concluded that CCD cameras and CMOS cameras are currently in the industry.
to sum up:
CCD and CMOS are twin brothers in the field of video surveillance like Gemini. As far as the current market situation is concerned, the two can be described as different. However, with the development of surveillance cameras, in addition to the two advantages of price and manufacturing process, CMOS in the future will be able to stand out in the field of video surveillance.
Jiangsu Dingtian Stainless Steel Products Co., Ltd. , http://www.dingtiancasting.com