Security Know How: Basic concepts of CCD chips that must be known for security work

    The security industry has been around for many years, and there are millions of people engaged in security. However, the security industry has always been an emerging industry. It is impossible to find books on monitoring technology in major bookstores. For many years, people have not been very clear about the concept of monitoring chips. Today, Know How hopes to bring you more understanding and knowledge.

　　1. What is CCD?

　　A: CCD stands for charge coupled device. It is made of a highly sensitive semiconductor material that can convert light into electric charge. Therefore, it has the advantages of high sensitivity, resistance to strong light, small distortion, small size, long life, and vibration resistance. The photosensitive element on it is called a "pixel". The more CCD pixels there are and the larger the size of a single pixel, the clearer the collected image will be.

　　2. What are the sizes of CCD chips?

　　A: Common CCD imaging sizes are 1/2", 1/3" and 1/4". The smaller the size, the smaller the volume of the surveillance camera can be. Under the same optical lens, the larger the imaging size, the larger the field of view. Chip specifications Imaging surface size (width x height) Diagonal (1/2) 6.4x4.8mm 8mm (1/3) 4.8x3.6mm 6mm

　　3. What is a CCD HAD sensor?

　　A: The HAD (Hole-Accumulation Diode) sensor is a unique structure of Sony, which adds a positive hole accumulation layer on the surface of the n-type substrate, p-type, and n+2 pole. The design of this positive hole accumulation layer can solve the dark current problem that is often found on the sensor surface. In addition, the vertical tunnel that electrons can pass through is designed on the n-type substrate, which increases the aperture ratio, in other words, also improves the sensitivity. In the early 1980s, Sony pioneered the use of it in variable-speed electronic shutter products, which can also obtain clear images when shooting fast-moving objects.

　　4. What is super HAD CCD?

　　A: The unit area of ​​CCD is getting smaller and smaller. The micro-lens technology can no longer improve the brightness. If the magnification of the amplifier inside the CCD component is increased, the noise will also be increased, and the image quality will be significantly affected. Sony has taken a step further in the research and development of CCD technology, improving the technology of using micro-lenses in the past, improving the light utilization rate, and developing the technology to optimize the shape of the lens, namely Sony SUPER HAD CC technology. Basically, it is a design that improves the brightness by improving the light utilization efficiency, which also laid the foundation for the current basic CCD technology.

　　5. What is Exview HAD CCD?

　　Answer: Infrared light with a longer wavelength than visible light can also be converted into photoelectricity in semiconductor silicon chips. However, up to now, CCD has been unable to collect these charges after photoelectric conversion into the sensor in an effective way. For this reason, Sony's newly developed "Exview HAD CCD" technology in 1998 can effectively convert near-infrared light that was not effectively utilized before into image data. The visible light range is expanded to infrared, which greatly improves the brightness sensitivity. When using the "Exview HAD CCD" component, high-brightness photos can be obtained even in dark environments. In addition, the smear linear component that leaked out to the vertical CCD part during the photoelectric conversion in the deep layer of the silicon wafer can also be collected in the sensor, so the noise that affects the image quality will be greatly reduced.

　　6. What are scanning formats and what are the commonly used ones?

　　A: Television standards refer to the specific system and technical standards adopted by a country's television system. Specifically, there are three television standards in the world. Most countries in the world (including most European countries, Africa, Australia and China) currently use the PAL system, which uses a 25fps frame rate; the United States, Japan, Canada and other countries use the NTSC system developed by the National Television Standards Committee (NTSC), which uses a 30fps frame rate (to be precise, 29.97 fps); another standard, the SECAM system, is mainly used in France, the former Soviet Union and Eastern European countries.

　　7. How does a CCD camera work?

　　A: The image of the object is focused onto the CCD chip through the lens. The CCD accumulates charges in proportion to the intensity of the light. The charges accumulated by each pixel are moved outward point by point under the control of the video timing. After filtering and amplification, a video signal is output. The video signal is connected to the video input terminal of a monitor or TV, and the same video image as the original image can be seen.

　　8. What is the pixel of a surveillance camera?

　　A: Pixel is one of the important indicators to measure the CCD of a camera. Generally speaking, the higher the pixel, the better the image quality. But on the other hand, it does not mean that the higher the pixel, the better. For the same picture, the higher the pixel, the stronger its ability to analyze the image. In order to obtain high-resolution images or pictures, the amount of data it records must be much larger, and the requirements for storage devices are much higher.

　　9. What is the resolution of a camera?

　　A: Usually refers to horizontal resolution, unless "vertical" is specifically specified. The indicator for evaluating camera resolution is horizontal resolution, and its unit is TVL line, that is, the number of black and white scanning lines that can be distinguished after imaging. The resolution of commonly used black and white cameras is generally 300-1000, and that of color cameras is 300-700. The larger the value, the clearer the image.