CCD and CMOS both the performance gap is not great technically quite different, just the CMOS network camera on the light source of the request must be high, but now the problem has been basically solved. Judge a product's performance is good or bad, several technical indicators for CCD and CMOS sensors also have a few hard targets. The main technical indicators of the sensor pixels, the size of the target surface, sensitivity, electronic shutter, frame rate, signal-to-noise ratio. Many photosensitive sensor unit, they can convert the light into a charge, thereby forming the electronic image corresponding to the scene. In the sensor, each photosensitive unit corresponding to a pixel (Pixels), more pixels represent it able to sense more of the details of objects, so that the image becomes clear. The higher the pixels, the means the sharper imaging results. Target Size: the size of the portion of the image sensor photosensitive. Usually expressed in inches, and televisions, usually the data refers to the length of the diagonal of the image sensor, such as the common 1/3 inch, the greater the target surface, means that the amount of light through the better, and the target surface, smaller relatively easy to obtain a greater depth of field. Such as 1/2 inches can have a relatively large amount of light, while the 1/4 inch can be relatively easy to obtain a greater depth of field. Sensitivity: the intensity of the incident ray is sensed by a CCD or CMOS, and the associated electronic circuit. The higher the sensitivity, the photosensitive face the light sensitivity, the higher the shutter speed is especially important when shooting moving vehicles, night surveillance. Electronic shutter: a term cf camera's mechanical shutter function. The control of the image sensor photosensitive time, is the accumulation of the signal charge due to the image sensor photosensitive value, the photosensitive longer the signal charge accumulation time is longer, the greater the amplitude of the output signal currents. The faster the electronic shutter, the lower the sensitivity for shooting in bright light. Frame rate: refers both to the number of pictures that record or playback unit time, continuous play a series of images will be generated animation, based on the human visual system, when the picture playback speed is greater than 15 / s, the human eye basically can not see the picture jumps; reach between 24 / s ~ 30 width / s has been basically aware of the less than a flicker. The number of frames per second (fps), or frame rate represents the number of times per second that can be updated graphics sensor disposal sites. High frame rate can get smoother, more realistic visual experience. SNR: signal voltage noise voltage ratio, the signal-to-noise ratio of the unit dB. The general ip camera given signal-to-noise ratio values are the AGC (Automatic Gain Control) off when the value, because when the AGC is turned on, the interested smaller signals to be improved, so that the noise level is also a corresponding increase. SNR typically 45 to 55dB, 50dB, then the image has a small amount of noise, but the image quality is good; is 60dB, then the image quality, noise does not occur, the signal-to-noise ratio greater the more noise control better. The move toward high-quality, high-frame rate, high dynamic, low-light direction with the video surveillance industry image, hd ip camera CCD sensor as the carrier difficult to break above the pressure of the cost, resolution technology bottleneck, makes the development of CMOS sensor technology to fill the space, thus becoming the security industry, high-definition video images and high imaging speed application the mainstream image sensor technology. Current monitor with hd ip camera products, mainly to 130 million and 200 million pixels, and 2000000 and the following pixel CCD and CMOS sensors applications less, more than 2 million pixels network camera products mainly CMOS-based, but overall, high-definition network camera performance in low-light, wide dynamic aspects still to be improved. The main advantage of the CMOS sensor technology: low cost, the manufacturing process is simple, and low power consumption. At the same time, after the development in recent years, CMOS sensor imaging wafer technology as well as the imaging process made considerable progress. Imaging wafer technology from early 3T technology began to experience a 4T, 5T, 6T, 7T, until the latest 8T technology, making the CMOS imaging technology gradually matured applications, the application of this technology in large part to circumvent the CMOS shortcomings, the advantages have been greatly enhanced. In addition, CMOSSensor technology applications in the industry has also made a good adaptability (such as high-speed capture, Blooming, Smear, etc.). CMOSSensor semiconductor process to make low-cost, high-definition, big-screen imaging effects become possible. Currently, the market for professional supply security monitoring CMOS sensor chip suppliers include: Sony, Aptina, and Taiwan LightTech electronics.
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