Protective covers are used to protect cameras and lenses, which are divided into indoor and outdoor. Attention should be paid to when selecting protective cover:
1) According to the installation position, correctly select the indoor or outdoor protective cover. The main function of indoor protective cover is to prevent dust, while the main function of outdoor protective cover is to protect the camera from working normally in various harsh natural environments (such as rain, snow, low temperature, high temperature, etc.). Therefore, the outdoor all-weather protective cover not only has a stricter sealing structure, but also has many functions such as wiper, spraying, heating and cooling. This determines that the price of outdoor protective cover is much higher than that of indoor protective cover. It should be noted that, because the temperature in some areas does not change much in four seasons, which is within the working temperature range of the camera, ordinary outdoor protective covers without constant temperature function can be selected to reduce the cost.
2) Select the protective cover with corresponding size. The size of the protective sleeve should be greater than the sum of the camera and lens, otherwise the camera and lens cannot be installed.
3) If you choose a protective cover with constant temperature function, you should consider the power supply of the protective cover; Select the protective sleeve with wiper function. If there is a decoder, it can be controlled by the decoder. If there is no decoder, consider adding a relay to control it.
The indoor protective cover must be able to protect the camera and lens from dust, impurities and corrosive gases, and at the same time, it must be able to cooperate with the installation site to prevent damage. Indoor shielding is usually made of painted or anodized aluminum, painted steel, brass or plastic. If plastic is used, it should be fire-resistant or flame retardant. The protective cover must have sufficient strength, the installation interface must be firm, and the window should be clear and transparent safety glass or plastic (polycarbonate). The design position of the electrical connection port should be convenient for installation and maintenance.
The working temperature of the camera is -5℃ ~ 45℃, and the optimum temperature is 0℃ ~ 30℃, otherwise the image quality will be affected and even the camera will be damaged. Therefore, the outdoor protective cover should adapt to various climatic conditions, such as wind, rain, snow, frost, low temperature, exposure, dust and so on. The outdoor protective cover will be equipped with auxiliary equipment, such as sunshade, internal/external fan, heater/defroster, wiper, washer, etc. Depending on the place of use.
First of all, the outdoor protective cover should be highly sealed to prevent rainwater from entering. At the same time, the wire inlet should be opened under the protective sleeve to prevent rainwater from flowing back into the protective sleeve along the cable. Wipers should also be installed in front of the protective cover to clean up the accumulated rain and dirt in time, so that the camera can take a clear image through the glass. When frost and snow accumulate, the defroster in front of the cover or on the glass will melt the window.
Secondly, a heater should be installed in the protective sleeve to heat it in a low temperature environment to improve the internal temperature of the protective sleeve and ensure the normal work of the camera/lens; The built-in or external fan can circulate the air in the fume hood and reduce the temperature in the fume hood; In places with more wind and sand and less rain, it is also necessary to configure a cleaner to cooperate with the wiper to clean the window glass at any time to ensure the image monitoring effect.
There are two auxiliary equipment control functions of outdoor protective cover: automatic control and manual control. For example, the heater/defroster and fan are automatically turned on or off by the temperature sensor in the protective cover, while the actions such as wiper and washer are realized by the controller by controlling the operation of the equipment.
Outdoor shielding is generally made of aluminum, coated steel, stainless steel or plastic, which can be used in outdoor environment. Manufacturing materials must be able to withstand ultraviolet radiation, otherwise aging phenomena such as cracks, fading and strength reduction will soon occur. Stainless steel shielding should be used in the environment that needs durable shielding, high safety and resistance to man-made damage; Properly treated aluminum shield is also a kind of shield with excellent performance. There are three treatment methods: polyurethane baking paint, anodizing, anodizing and painting. In the environment with corrosive gas, aluminum or steel should not be selected for mutual assistance; In the salt spray environment, a protective cover made of stainless steel or special plastic should be used.
In addition, in order to improve the safety performance of the protective cover and prevent man-made damage, many protective covers are also equipped with anti-disassembly switches, which will send out an alarm signal once the protective cover is opened.
There are many kinds of shielding in monitoring system, which can be generally divided into rectangular shielding, wall or ceiling shielding, spherical shielding, angular shielding, slope shielding and so on.