Infrared dome camera is a camera with infrared light, used in light dim or no light environment. A self-lens focal length is fixed, the price is low; the other is the infrared one machine, is one machine based on the installation of infrared light. Infrared hemisphere in the surveillance camera with night vision distance, hidden strong, stable performance and other prominent advantages, and thus in the CCTV night vision monitoring to occupy most of the market. How do you distinguish between pros and cons in the infrared dome camera market? The excellent infrared dome camera must have the following performance:
1. Infrared lamp working conditions
In general, the infrared dome camera's infrared lamp radiated power is proportional to the forward operating current, but close to the maximum current rating of the forward current, the device temperature increases due to the heat of the current, the light emission power. Infrared diode current is too small, will affect the radiation power play, but the working current is too large will affect its life, and even the infrared diode burned. When the voltage across the forward threshold voltage (about 0.8V or so) the current began to flow, and is a very steep curve, indicating that its working current requirements are very sensitive. So the working current is accurate and stable, otherwise it will affect the radiation power and its reliability. The radiated power decreases as the ambient temperature increases (including the ambient temperature generated by its own heat). Infrared light, especially long-distance infrared light, heat consumption is the design and selection should pay attention to the problem. Therefore, the use of infrared dome infrared light must have a good constant current power supply, good thermal design. Midway Communications MCD, MDD, MED, MBB series cameras are equipped with high-power infrared light (up to 24), and the use of high-power constant current power supply, internal cooling design, which can achieve long-distance night Depending on (up to 220 meters) and long life of infrared light effect.
2.Infrared light utilization and red storm problem
What is red storm? The red storm is due to the emission of infrared light that contains visible light. Infrared light can be done without red storm (using 940 ~ 950nm wavelength infrared tube) or only weak red storm. Midway communication company uses the United States Oster (AUCSITER) infrared technology, through the premise to ensure that the infrared light power, reduce the infrared light their own heat, adjust the infrared light angle, so that the effective utilization of infrared lamps reached 90%. In the choice of infrared light, select the larger wavelength (910nm) infrared light, strictly reduce the red storm, to achieve the effect of micro-red storm.
3. Fog frost problem of infrared dome camera
Fog, frost formation is due to the saturated water vapor in the air condensed from condensation, due to cold environment strong and weak, respectively, condensed into frost and fog. Infrared dome camera in the course of work, especially outdoor cameras often due to seasonal changes, day and night temperature difference, as well as rain and snow environment and other reasons in the hood window glass fog or frost, resulting in the camera can not see the object, directly affect the monitoring effect. Midway through the use of advanced electronic defrost circuit, the effective control of the saturated vapor concentration within the cavity, so that the automatic defrosting.
4.Infrared hemisphere window glass cleaning
The camera works in rain and snow or dusty environments, and the window glass of the protective cover is prone to dirt, causing the camera to block. The solution is usually to add a wiper on the hood, clean the glass by controlling the wiper; another way is to use an invisible wiper window glass. Compared with the ordinary window glass, stealth wipers window glass with the exclusion of water, dust, snowflakes function.
5. Infrared dome camera temperature
Due to the configuration of the larger heat of the infrared light, infrared light in the start, the entire working hours (12 hours) in the front of the infrared dome camera will have heat concentration, that is, the cavity front temperature is high, such as can not heat evenly Will affect the camera and other parts of the normal work. Midway communications company through the design of the use of forced cooling cooling effect of automatic air conditioning, a good solution to this problem. Automatic temperature control The principle of Peltier effect, the temperature control circuit can be automatically adjusted, the temperature inside the protective cover in the normal operating temperature range of the camera, the factory temperature set below +5 ℃ heating, +40 ℃ above cold. Experiments show that the infrared camera can be -40 ℃ ~ +70 ℃ (direct sunlight) in the outdoor natural environment to work properly.
6. Infrared hemisphere is completely closed
In addition to constant temperature, the use of automatic heating and air conditioning, another advantage is that the infrared dome camera can be made completely closed, leaving no cooling holes, to prevent dust, moisture, corrosive gas into, so that it can adapt to dusty harsh environment , Such as large coal mines can also be used normally.
7. Heat problems
Due to the configuration of the larger heat of the infrared light, infrared light in the start, the entire working hours (12 hours) in the front of the infrared camera will have heat concentration, that is, the cavity front temperature is high, such as can not heat evenly Will affect the camera and other parts of the normal work. Such as 50 ¢ 5 infrared light board, long time to run, LED board temperature can reach almost 90 degrees.
As the infrared light emitting LED radiation power is proportional to the current, many non-standard manufacturers to increase the way to increase the current radiation effect, but the higher the current the higher the temperature. Although the effect of irradiation increased, but the machine itself due to LED overheating will be a lot of damage. Among them, LED board behind the CCD is the most direct victim. CCD generally only support to 60-70 degrees long.
In order to solve this problem, the various manufacturers to use the method is different. There are generally the following:
1, reduce the current. The use of small power consumption of infrared light instead of high-power infrared light, although reducing the heat, but when the long distance irradiation, the effect is certainly not the latter.
2, in the machine inside the cooling fan, this effect is certainly there, but that the test of the fan is very strict, and added a fan for the design of the shell is also a test, to ensure aesthetics but also practical.
3, the use of constant current power supply. Keep the current constant, control the heat dissipation of the LED.
4, LED lights group arrangement. For example, with 24 infrared, it can be arranged in three groups to reduce heat.
5, the choice of structural materials. For example, LED light board and shell selection of aluminum and other heat better than the material.
6, the use of forced cooling cooling effect of automatic air conditioning, automatic adjustment of the body temperature, a good solution to this problem.
8. Infrared lamp life problem
From the perspective of the red light, raising life and increasing the distance is often contradictory. Because if the manufacturers need to increase the infrared light irradiation distance, it is necessary to increase the power of the infrared light, and increase the power is bound to shorten the life of infrared light, some manufacturers in order to blindly pursue the distance of infrared light, deliberately increase the power of infrared light, Making the infrared lamp life greatly reduced. And with the increase in power, making the camera internal temperature increases, making the camera is easy to damage, resulting in a vicious cycle.
In this case, we can not improve the supply current to improve the brightness of the infrared light, so that overload work, although the surface optimization of the infrared performance, in essence, seriously affect the infrared lamp life attenuation. To improve the life of the infrared light first to ensure that the infrared light does not load, while not loading by increasing the number of infrared light to ensure effective distance; some manufacturers through the use of aluminum substrate and other high conductivity materials, increase the air-cooled device Use, increase the shell area, etc. to increase the body's cooling capacity, thereby enhancing life.
In the circuit control part, there are some manufacturers using pulse width modulation law to keep the infrared lamp current constant, thereby reducing the infrared light heating, in order to achieve the purpose of extending life. With the pulse width modulation law, no matter how the external input current fluctuations, through the circuit into the infrared light current is very stable, so as to ensure that the infrared lamp to maximize their efficiency and extend life.
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