Infrared surveillance camera is a CCTV surveillance camera equipment that integrates the camera, rain cover, infrared LED lights and other components into one. The basic principle of night vision is to use the ordinary camera equipped with light CCD to feel the spectral characteristics of infrared light source (that is, you can feel visible light and infrared light), and use the additional LED infrared light as "light source" at night or micro Imaging in light.
Considerations when choosing an infrared surveillance camera
The light source emitted by the infrared lamp and reflected back is invisible light of the human eye, which can be captured only through the optical chip CCD. Therefore, the key points to distinguish the advantages and disadvantages of an excellent infrared surveillance camera are the lens LENS, the optical chip CCD and Digital Signal Processor DSP.
(A) choose to leave room when choosing the irradiation distance of the infrared lamp
1. While giving the camera's * illumination, also give the required value of the aperture F, and the zoom lens generally only gives a * value of 1: F, that is, the smallest value of the aperture F (the actual size of the aperture), F = f / D, then D is a fixed value. When the focal length of f is increased by 10 times, F becomes very large (that is, the actual size of the aperture becomes very small). Luminous flux will be greatly affected.
2. When using automatic aperture lens, automatic gain control or automatic electronic shutter camera, the lens aperture F value will also change. For example, if there is a scene near the camera that reflects strong light back to the camera, or there is light nearby to illuminate the camera, the sensitivity of the camera will be reduced, the size of the automatic aperture will be reduced, and the luminous flux will be greatly affected.
3. The * illuminance given by the camera. What is the * illumination concept here? The video signal generated by the camera has a nominal value of 1V and a standard value of 0.7V, and the video signal value under * illumination is 1 / 3-1 / 2 standard plant. Therefore, the camera's image at * illuminance will never be "like daylight".
4. The protective cover also affects the effect of the infrared light. During the transmission of infrared light, the transmittance and reflectance are different through different media. Different window glass, especially the automatic defrost coated glass, has different attenuation of infrared light.
With the rapid development of infrared night vision systems for infrared surveillance cameras, the production and supply of infrared lights will also increase, but red light products are not as easy as some people think, and the conditions are different in terms of technology, testing equipment, etc., I hope users Compare more and choose carefully. When using infrared light of infrared surveillance camera, users must first read the instruction manual carefully, especially the precautions to ensure the safety of personal equipment. Check whether the compatibility mentioned above meets the requirements and whether the influencing factors to be considered are taken into account. If the requirements are not met, the equipment used can be adjusted in a timely manner.
The user should not increase the power supply voltage without authorization, because the infrared lamp of the infrared surveillance camera is designed in consideration of both its full irradiance and its safety and reliability. Increasing the power supply voltage may cause the infrared lamp to burn out, and it should not be dismantled and changed without authorization. If this is done, the manufacturer may no longer be responsible for repairs. If there is a problem with the infrared light of the infrared surveillance camera, please contact the manufacturer or supplier.
5. The sharpness of the image produced by the camera at * illuminance is measured with a TV signal test card. The black and white stripes require black reflectance to be close to 0% and white reflectance to be greater than 89.9%. And we sometimes do not have such conditions when observing on the spot, for example: the reflectance of leaves and grass is very low, the contrast is small, it is difficult to obtain a clear image.
(B) the choice of infrared lamps * the important issue is the set
That is, the complete set of infrared light and camera, lens, protective cover, power supply, etc.
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