The choice of infrared and night vision surveillance products focuses on the integrity of the system. It is necessary to consider the main products and interface devices of low illumination and night vision. What is the principle of matching infrared light and night vision cameras?
In the installation and construction of infrared light and night vision cameras, they must be designed with low-light and night-oriented monitoring system engineering. All equipment should be considered in order to avoid purchasing cameras, lenses, protective covers and power supply equipment. After that, consider buying infrared projection lamps, etc., which will cause problems in matching and effects between devices. The following is the principle that the engineering installer must keep the infrared light and night vision camera.
1, pay attention to the camera's caliber size and amount of light
The size of the camera's photosensitive components has been miniaturized. Currently, the size of the camera on the market is generally from 1/1.8" to 1/4", and the amount of light passing through the photosensitive unit and the lens depends on the size of the camera and the aperture is small. The amount of light received is less, and vice versa. In addition, special attention should be paid to the principle of matching with the lens, that is, the focal length value is inversely proportional to the aperture diameter. For example, the aperture ratio of 4mm may be f1.2-1.4, but the aperture of 50mm or even 200mm may be only f1.8-2.2. Therefore, it will also affect the amount of light passing through, and the corresponding brightness of the screen will also affect the imaging distance when it is combined with infrared projection.
2, must use low light conditions camera
The minimum illuminance of the camera is the lowest brightness of the subject. The camera manufacturer will give the lowest illuminance of the f-number of different apertures, which is the minimum illuminance (also called sensitivity) of this camera. If the minimum illumination of the selected camera is higher than the maximum illumination requirement of the infrared projection lamp, the effective distance of the infrared lamp will be affected by the minimum illumination, so that the projection distance becomes shorter or the imaging range is insufficient, resulting in a bright spot on the center of the picture and a dark display effect. . Therefore, whether the camera is a true low-light camera is a very important indicator for monitoring low-light environments.
3, or you can use black and white camera or day and night color / black and white camera
In addition to the low-illumination performance of the camera itself, the CCD has a wide sensing spectrum range, which can sense the visible light region and a certain infrared spectrum range. Therefore, the auxiliary infrared light source can display a clear black-and-white picture without any illumination at night. . The day/night color/black-and-white camera can transmit a color signal, which separates the green, blue, and red primary color video signals from the output signal of the CCD photosensitive component, and then synthesizes the color television signal (the color signal only senses the visible light spectrum). With the advancement of imaging technology, the switching of digital circuits has been used to realize the infrared sensing advantage of day and night color/black and white cameras.
4, pay attention to hidden requirements
Using shielding technology, the infrared illumination range covers only the buildings or facilities that need to be protected, so as to avoid light leakage and disturbing people or causing light damage. In addition, photosensitive, thermal or photoelectric inductive lighting is used, and the lighting is activated when the illumination is below a critical value or when someone is too close to an illegal intrusion.
5, make good use of high-speed positioning infrared camera
CCD cameras are becoming smaller and smaller, and the lens is also compact and versatile. It has been able to memorize multiple sets of telescopic and focal length combinations. The light weight of the camera and the lens makes the electric camera of the load camera more flexible, and the preset orientation (PTZ, presetIRCamera), which is equipped with an infrared camera or an infrared projection lamp, and defaults various types of trigger devices, which can almost be achieved. Point the infrared night vision camera "real time" to the trigger point and capture the target image.
6, camera and lens function matching requirements
Cameras usually have automatic electronic shutter, AES and automatic gain control, AGC and other functions to assist in night vision settings and camera conditions. The night vision requires a lens with an auto iris function to achieve day and night illumination changes. The automatic illumination adjustment of the lower camera.
7, camera power supply requirements
The power supply of the front-end equipment of the monitoring system should be designed in a unified manner. The infrared projection lamp part must take into account the influence of the operating current of the infrared lamp and the infrared LED on the supply voltage, and the length of the transmission cable also affects the DC voltage attenuation. When there is a large difference between the distances of multiple infrared lamps from the control room, the DC12V centralized power supply may cause the infrared lamp supply voltage to be close to the control room to be high, and the infrared lamp supply voltage far from the control room is low. In addition, the deviation of the power supply voltage adjustment may cause problems such as voltage or current impedance, so that the life of the infrared lamp is shortened or even burned. The infrared lamp with too low voltage has insufficient transmission power, which makes the projection range, distance and brightness insufficient, and reduces the imaging effect. Therefore, it is recommended to use AC24V AC power supply or DC power supply as much as possible. It can ensure stable DC power supply when the voltage fluctuates at AC100V-240V, which ensures the stable operation of the infrared lamp.
The principle of matching infrared light and night vision camera is introduced here. More information about infrared surveillance cameras, please continue to pay attention to the hot security investment network.
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