In order to ensure the reliability of the camera and the lens, and to extend the service life, the camera must be equipped with a cover with a variety of special protection measures, called a protective cover. In addition, the protective cover can also prevent human damage to the camera and the lens. Similar to PTZ equipment, protective covers are generally divided into general-purpose and special-purpose types, and can be divided into indoor type and outdoor type.
First, universal protective cover
The indoor protective cover must be able to protect the camera and the lens from dust, impurities and corrosive gas contamination, and at the same time be able to meet the installation site to prevent damage. Indoor shields are generally made of painted or anodized aluminum, painted steel, brass, or plastic. If plastic is used, it should be flame-retardant or flame-retardant. The protective cover must have sufficient strength, the mounting interface must be strong, and the window should be clear and transparent safety glass or plastic (polycarbonate). The design location of the electrical connection should be easy to install and maintain.
The operating temperature of the camera is -5°C to 45°C, and the most suitable temperature is 0°C to 30°C, otherwise it will affect the image quality and even damage the camera. Therefore, the outdoor protective cover must adapt to various weather conditions, such as wind, rain, snow, frost, low temperature, exposure, sand and dust. The outdoor protective cover will be equipped with different equipment such as sun shields, interior/exterior fans, heaters/defrosters, wipers, and washers.
First, outdoor enclosures must have high tightness to prevent rainwater from entering. At the same time, the inlet opening should be opened under the protective cover to prevent the rain from flowing back into the protective cover along the cable. A wiper should also be installed in front of the hood so that the accumulated rainwater and dirt can be cleared in time so that the camera can take clear images through the glass. The defroster on the front of the hood or on the glass melts the window when it accumulates frost and snow.
Secondly, a heater should be installed inside the protective cover to heat in a low temperature environment to raise the temperature inside the protective cover to ensure the normal operation of the camera/lens; the built-in or external fan can make the air in the cover circulate and reduce the temperature inside the cover. It is also necessary to consider the configuration of cleaners in locations where there is little wind and sand and little rain, so that the window glass can be cleaned at any time with the wiper to ensure the image monitoring effect.
The auxiliary equipment control function of the outdoor protective cover is automatic control and manual control, such as the heater/defroster and the fan are automatically activated or closed by the temperature sensor inside the protective cover, like a wiper, a washer, etc. The action is achieved by the control personnel through the operation of the control device.
Outdoor shields are generally made of aluminum, coated steel, stainless steel, or plastic that can be used in outdoor environments. The manufacturing materials must be able to withstand the irradiation of ultraviolet rays, otherwise it will soon appear cracking, fading, reduced strength and other aging phenomena. Stainless steel shrouds should be used in environments where shrouds are required to be durable, high in safety, and resistant to vandalism; properly treated aluminum shrouds are also excellent shrouds and are handled in three ways: polyurethane paint, anodized Anodized plus paint. In a corrosive gas environment, aluminum or steel should not be selected for mutual assistance; in a salt spray environment, shields made of stainless steel or special plastics should be used.
There are various kinds of protective covers in the monitoring system, which can be generally classified into rectangular guards, wall or ceiling guards, ball guards, corner guards, and slope guards according to their shapes.
(A) Rectangular Shroud Rectangular shroud is the most common protective cover for surveillance systems. It is low cost, strong and durable, with various dimensions and beautiful appearance. Rectangular indoor shields do not require special anti-rust treatment, commonly used painted or anodized aluminum, steel or high-impact plastics, such as PVC, ABS or polycarbonate (such as Lexan) and other materials.
The opening structure of the rectangular protective cover includes a top cover dismantling type, a front cover dismantling type, a slide pull-out type, a top cover strut type, a hinge suspension type, a top cover sliding type, and the like, and various structural methods are installed and overhauled. For the purpose of convenient maintenance.
(b) Ball type ball guards are available in both hemispherical and global types. In general, most of the outdoor applications use globe-type domes. In indoor applications, hemispherical or global-type shields are selected according to the site environment. Global-type shields generally use bracket-suspended or in-ceiling mounts. Hemispherical shields are most commonly ceiling-mounted and ceiling-embedded.
There are three kinds of plastic domes that can provide scene light to the lens in the hood: transparent, coated (translucent aluminum or chrome plated) and brown. When the dome is only used to protect the camera and lens without the need to conceal the camera, transparent domes are often used. The transparent dome has minimal light loss (10% to 15%). If you want to hide the camera's pointing for additional security, you need to use a coated or brown dome cover. After passing through the coated dome, the light attenuates by approximately two f-stops (approximately 75% attenuation). The brown dome is relatively effective and the light attenuation is only about 1 f-stop, about 50%.
Different from the excellent optical quality and light transmission performance of the flat plastic or glass used for the rectangular shield window, all the domes will bring a certain degree of optical distortion to the image, and the high-quality spherical shield has little optical distortion. The axis of the camera must be perpendicular to the outer plane of the intersection of the dome, so the distortion is at least uniform. The main effect is that the focal length of the lens produces a slight change. This change is generally not easy to detect or no other annoying, otherwise the image There will be horizontal or vertical stretching, especially when the dome is mounted in the dome. When the camera rotates often, distortion of the image is easily found. Therefore, optical distortion is an important indicator of the inspection of the dome.
The outdoor type dome cover is similar to the rectangular one except that the sealed protection level is to be used in outdoor environments, and fans, heaters, and other devices are installed inside to compensate for changes in outdoor ambient temperature. Since the dome cover cannot be equipped with a wiper like a rectangular shield, it is generally equipped with a rain grate or other similar device to prevent excessive rain from falling through the lower dome cover to form a water spot, while also having a certain shade effect. .
(c) Corner Guards Corner Guards are guards designed for interior corners where the two walls and the ceiling join. It is usually installed in small rooms or halls, elevator cars, stairwells or prison cells.
The camera is mounted diagonally inside the corner guard and points to the surveillance area under the ceiling. The observation window of the guard is perpendicular to the axis of the lens. There is also a special corner guard. The camera is pointing above the ceiling in the protective cover. The front of the camera is equipped with the reflector of the front of the audience. It can reflect the scene under the ceiling to the camera. The position of the reflector can be adjusted up and down. Change the camera's field of view. Because the mirror's scene image is inverted, the camera must be installed upside down.
(d) Embedded guards The built-in guards are usually exposed on the ceiling and wall, partially exposed, and partially concealed. This type of protective cover is suitable for applications that require a more subtle installation.
In addition, in order to increase the safety performance of the protective cover and prevent man-made damage, many protective covers are also equipped with a tamper switch. Once the protective cover is opened, an alarm signal will be issued.
Second, special purpose shield
In some cases, the camera must be installed under a harsh environment. Not only must it be highly sealed, resistant to extreme cold, resistant to extreme heat, resistant to wind and sand, and protected from rain and snow, but it should also be resistant to smashing, shock and corrosion. It even needs to be used in an explosive environment, so special protective covers with high safety must be used.
(i) High-security hoods These hoods are also commonly referred to as armored hoods. These hoods are suitable for installation in prisons or other places that are easily politically damaged. They are made of 0.134 inch thick No. 10 welded steel. Into a window material of 1/2 inch thick, wear-resistant polycarbonate. The shield can withstand the impact of hammers, stones, or some bullets without being penetrated or cracked. The enclosure is closed with a large mechanical lock and should not be disassembled.
(II) Special Shields for Elevators This is a guard designed for use in elevators and has been hardened. The shroud is made of stainless steel and has a tamper-proof function. The lead-in wire is on the back of the shroud and is not accessible to ordinary people. The window is a wear-resistant polycarbonate. The best pointing direction of the camera is to form a 45° angle with the two walls perpendicular to each other, and to form a downward angle of 45° with the ceiling plane. When the horizontal field of view exceeds 90° (wide angle), the entire car can be observed without any Any dead ends.
(3) Dust-proof shields High-dust shields are similar to general-purpose shields except that they are completely isolated from the outside and can be used in sandy and dusty environments. If stainless steel is used, they can also be used for corrosion. In a sexual environment. The window material is a tempered glass that provides maximum safety, corrosion and wear resistance. To avoid overheating in the hood, a hood and a fan are often provided, and the internal temperature can also be maintained through a filtered external compressed air source.
(4) Explosion-proof shields The explosion-proof shields are the same as those of the explosion-proof heads, and they must also comply with the safety regulations for explosion-proof and dust-proof electrical equipment. The materials used are the same as those used for the pan tilt, which are usually thick-walled all-aluminum structures or stainless steel structures. Explosion-proof shields are generally 6", 8", 10" in diameter, etc. The inlet excuse is equipped with explosion-proof seals. If the explosion-proof shield inside the space to accommodate the camera, the lens assembly can also be installed inside the decoder will avoid the decoder Rebuild the explosion-proof housing.
(v) High-pressure shields High-pressure shields can be used in hazardous atmospheres. The requirements of the National Fire Protection Association can be met by filling the housing with pressurized inert gas. This shroud is made of corrosion-resistant, thick-walled aluminum and its windows are 1/2 inch thick tempered polished glass. The shroud is filled with low pressure nitrogen at a pressure of 15 pounds per square meter. Nitrogen is completely inert and can avoid sparks in the shroud or explosions caused by electrical faults. There is a sealing O-ring seal between the shield body and the outer cover. All electrical connections must be routed through a hermetic seal.
(6) High-temperature shield The high-temperature shield refers to a shield that protects the camera and lens from working normally when the camera is used in an environment where the natural convection and radiation heat exchange cannot reach the normal working temperature when the temperature exceeds 40° C. For high temperature environments, the protective cover should adopt special cooling and cooling methods. Common cooling systems include air cooling systems, water cooling systems, and semiconductor cooling systems, as well as vortex refrigeration, freon, and ammonia refrigeration.
The air-cooling system still uses the principle of air-flow cooling. Forced ventilation is used to send coolant (purified air) into the protective cover or protective cover compartment to bring out the heat inside the protective cover and achieve cooling. Forced ventilation cooling systems have direct cooling and indirect cooling.
When the ambient temperature is greater than 80 °C (such as heating furnaces, steel-making furnaces, etc.), the forced-air cooling system can be used when the temperature rise cannot be controlled by forced air cooling. The thermal conductivity and specific heat of water are both greater than that of air. Therefore, compared with air cooling, the thermal resistance of the relevant heat exchange steps is greatly reduced, and the heat exchange efficiency is improved. The shroud contains a built-in water jacket that effectively isolates the camera and lens from the outside environment. Depending on the application, the material can be aluminum or stainless steel. The hood is internally equipped with a fan to reciprocate the air in the hood to improve the heat transfer efficiency. There are two basic types of forced water cooling systems, one is water-cooled and dust-proof, and the structure is relatively simple. There is no alarm device and air filtration system, and the lens can use a fixed focus or zoom lens for 80°C environment. The other is a high-temperature furnace type, which can be used in environments with temperatures up to 1600°C. The structure is relatively complex. The entire system has alarms, air filtration systems, maintenance shutters, and high-temperature automatic exit systems.
High-temperature automatic exit system When detecting the failure of the camera cooling function, the exit device of the electro-pneumatic control will automatically withdraw the camera from the combustion chamber to avoid damage to the camera and lens. The system normally starts when the following conditions occur: (1) The temperature of the cooling water at the top of the probe exceeds a predetermined value (≤ 40°C); (2) The compressed air fails or the pressure drops to a predetermined value (≤ 0.4Mpa); (3) The air hole at the probe cleans or fails Drop to a predetermined value (≤ 0.02 MPa); (4) Water flow less than a predetermined value (≤ 6.8 L/min); (5) Air or water monitoring line interruptions; (6) Mains voltage failure; (7) The control device or control center room issues an exit command.
The semiconductor cooling system, also called thermoelectric cooling, is a cooling method based on several different semiconductor effects. When two different conductors form a galvanic couple, when they are supplied with a direct current, the endothermic and exothermic phenomena occur at the corresponding joints of the couple. This effect is very much in metal and more pronounced in semiconductors. The semi-conductor refrigeration has no mechanical rotation part, has the characteristics of no noise, no vibration, long life, simple structure, easy installation, high reliability, does not require coolant, the degree of cooling can be adjusted according to the current, its disadvantage is greater consumption law DC power must be used and the operating current is large.
First, universal protective cover
The indoor protective cover must be able to protect the camera and the lens from dust, impurities and corrosive gas contamination, and at the same time be able to meet the installation site to prevent damage. Indoor shields are generally made of painted or anodized aluminum, painted steel, brass, or plastic. If plastic is used, it should be flame-retardant or flame-retardant. The protective cover must have sufficient strength, the mounting interface must be strong, and the window should be clear and transparent safety glass or plastic (polycarbonate). The design location of the electrical connection should be easy to install and maintain.
The operating temperature of the camera is -5°C to 45°C, and the most suitable temperature is 0°C to 30°C, otherwise it will affect the image quality and even damage the camera. Therefore, the outdoor protective cover must adapt to various weather conditions, such as wind, rain, snow, frost, low temperature, exposure, sand and dust. The outdoor protective cover will be equipped with different equipment such as sun shields, interior/exterior fans, heaters/defrosters, wipers, and washers.
First, outdoor enclosures must have high tightness to prevent rainwater from entering. At the same time, the inlet opening should be opened under the protective cover to prevent the rain from flowing back into the protective cover along the cable. A wiper should also be installed in front of the hood so that the accumulated rainwater and dirt can be cleared in time so that the camera can take clear images through the glass. The defroster on the front of the hood or on the glass melts the window when it accumulates frost and snow.
Secondly, a heater should be installed inside the protective cover to heat in a low temperature environment to raise the temperature inside the protective cover to ensure the normal operation of the camera/lens; the built-in or external fan can make the air in the cover circulate and reduce the temperature inside the cover. It is also necessary to consider the configuration of cleaners in locations where there is little wind and sand and little rain, so that the window glass can be cleaned at any time with the wiper to ensure the image monitoring effect.
The auxiliary equipment control function of the outdoor protective cover is automatic control and manual control, such as the heater/defroster and the fan are automatically activated or closed by the temperature sensor inside the protective cover, like a wiper, a washer, etc. The action is achieved by the control personnel through the operation of the control device.
Outdoor shields are generally made of aluminum, coated steel, stainless steel, or plastic that can be used in outdoor environments. The manufacturing materials must be able to withstand the irradiation of ultraviolet rays, otherwise it will soon appear cracking, fading, reduced strength and other aging phenomena. Stainless steel shrouds should be used in environments where shrouds are required to be durable, high in safety, and resistant to vandalism; properly treated aluminum shrouds are also excellent shrouds and are handled in three ways: polyurethane paint, anodized Anodized plus paint. In a corrosive gas environment, aluminum or steel should not be selected for mutual assistance; in a salt spray environment, shields made of stainless steel or special plastics should be used.
There are various kinds of protective covers in the monitoring system, which can be generally classified into rectangular guards, wall or ceiling guards, ball guards, corner guards, and slope guards according to their shapes.
(A) Rectangular Shroud Rectangular shroud is the most common protective cover for surveillance systems. It is low cost, strong and durable, with various dimensions and beautiful appearance. Rectangular indoor shields do not require special anti-rust treatment, commonly used painted or anodized aluminum, steel or high-impact plastics, such as PVC, ABS or polycarbonate (such as Lexan) and other materials.
The opening structure of the rectangular protective cover includes a top cover dismantling type, a front cover dismantling type, a slide pull-out type, a top cover strut type, a hinge suspension type, a top cover sliding type, and the like, and various structural methods are installed and overhauled. For the purpose of convenient maintenance.
(b) Ball type ball guards are available in both hemispherical and global types. In general, most of the outdoor applications use globe-type domes. In indoor applications, hemispherical or global-type shields are selected according to the site environment. Global-type shields generally use bracket-suspended or in-ceiling mounts. Hemispherical shields are most commonly ceiling-mounted and ceiling-embedded.
There are three kinds of plastic domes that can provide scene light to the lens in the hood: transparent, coated (translucent aluminum or chrome plated) and brown. When the dome is only used to protect the camera and lens without the need to conceal the camera, transparent domes are often used. The transparent dome has minimal light loss (10% to 15%). If you want to hide the camera's pointing for additional security, you need to use a coated or brown dome cover. After passing through the coated dome, the light attenuates by approximately two f-stops (approximately 75% attenuation). The brown dome is relatively effective and the light attenuation is only about 1 f-stop, about 50%.
Different from the excellent optical quality and light transmission performance of the flat plastic or glass used for the rectangular shield window, all the domes will bring a certain degree of optical distortion to the image, and the high-quality spherical shield has little optical distortion. The axis of the camera must be perpendicular to the outer plane of the intersection of the dome, so the distortion is at least uniform. The main effect is that the focal length of the lens produces a slight change. This change is generally not easy to detect or no other annoying, otherwise the image There will be horizontal or vertical stretching, especially when the dome is mounted in the dome. When the camera rotates often, distortion of the image is easily found. Therefore, optical distortion is an important indicator of the inspection of the dome.
The outdoor type dome cover is similar to the rectangular one except that the sealed protection level is to be used in outdoor environments, and fans, heaters, and other devices are installed inside to compensate for changes in outdoor ambient temperature. Since the dome cover cannot be equipped with a wiper like a rectangular shield, it is generally equipped with a rain grate or other similar device to prevent excessive rain from falling through the lower dome cover to form a water spot, while also having a certain shade effect. .
(c) Corner Guards Corner Guards are guards designed for interior corners where the two walls and the ceiling join. It is usually installed in small rooms or halls, elevator cars, stairwells or prison cells.
The camera is mounted diagonally inside the corner guard and points to the surveillance area under the ceiling. The observation window of the guard is perpendicular to the axis of the lens. There is also a special corner guard. The camera is pointing above the ceiling in the protective cover. The front of the camera is equipped with the reflector of the front of the audience. It can reflect the scene under the ceiling to the camera. The position of the reflector can be adjusted up and down. Change the camera's field of view. Because the mirror's scene image is inverted, the camera must be installed upside down.
(d) Embedded guards The built-in guards are usually exposed on the ceiling and wall, partially exposed, and partially concealed. This type of protective cover is suitable for applications that require a more subtle installation.
In addition, in order to increase the safety performance of the protective cover and prevent man-made damage, many protective covers are also equipped with a tamper switch. Once the protective cover is opened, an alarm signal will be issued.
Second, special purpose shield
In some cases, the camera must be installed under a harsh environment. Not only must it be highly sealed, resistant to extreme cold, resistant to extreme heat, resistant to wind and sand, and protected from rain and snow, but it should also be resistant to smashing, shock and corrosion. It even needs to be used in an explosive environment, so special protective covers with high safety must be used.
(i) High-security hoods These hoods are also commonly referred to as armored hoods. These hoods are suitable for installation in prisons or other places that are easily politically damaged. They are made of 0.134 inch thick No. 10 welded steel. Into a window material of 1/2 inch thick, wear-resistant polycarbonate. The shield can withstand the impact of hammers, stones, or some bullets without being penetrated or cracked. The enclosure is closed with a large mechanical lock and should not be disassembled.
(II) Special Shields for Elevators This is a guard designed for use in elevators and has been hardened. The shroud is made of stainless steel and has a tamper-proof function. The lead-in wire is on the back of the shroud and is not accessible to ordinary people. The window is a wear-resistant polycarbonate. The best pointing direction of the camera is to form a 45° angle with the two walls perpendicular to each other, and to form a downward angle of 45° with the ceiling plane. When the horizontal field of view exceeds 90° (wide angle), the entire car can be observed without any Any dead ends.
(3) Dust-proof shields High-dust shields are similar to general-purpose shields except that they are completely isolated from the outside and can be used in sandy and dusty environments. If stainless steel is used, they can also be used for corrosion. In a sexual environment. The window material is a tempered glass that provides maximum safety, corrosion and wear resistance. To avoid overheating in the hood, a hood and a fan are often provided, and the internal temperature can also be maintained through a filtered external compressed air source.
(4) Explosion-proof shields The explosion-proof shields are the same as those of the explosion-proof heads, and they must also comply with the safety regulations for explosion-proof and dust-proof electrical equipment. The materials used are the same as those used for the pan tilt, which are usually thick-walled all-aluminum structures or stainless steel structures. Explosion-proof shields are generally 6", 8", 10" in diameter, etc. The inlet excuse is equipped with explosion-proof seals. If the explosion-proof shield inside the space to accommodate the camera, the lens assembly can also be installed inside the decoder will avoid the decoder Rebuild the explosion-proof housing.
(v) High-pressure shields High-pressure shields can be used in hazardous atmospheres. The requirements of the National Fire Protection Association can be met by filling the housing with pressurized inert gas. This shroud is made of corrosion-resistant, thick-walled aluminum and its windows are 1/2 inch thick tempered polished glass. The shroud is filled with low pressure nitrogen at a pressure of 15 pounds per square meter. Nitrogen is completely inert and can avoid sparks in the shroud or explosions caused by electrical faults. There is a sealing O-ring seal between the shield body and the outer cover. All electrical connections must be routed through a hermetic seal.
(6) High-temperature shield The high-temperature shield refers to a shield that protects the camera and lens from working normally when the camera is used in an environment where the natural convection and radiation heat exchange cannot reach the normal working temperature when the temperature exceeds 40° C. For high temperature environments, the protective cover should adopt special cooling and cooling methods. Common cooling systems include air cooling systems, water cooling systems, and semiconductor cooling systems, as well as vortex refrigeration, freon, and ammonia refrigeration.
The air-cooling system still uses the principle of air-flow cooling. Forced ventilation is used to send coolant (purified air) into the protective cover or protective cover compartment to bring out the heat inside the protective cover and achieve cooling. Forced ventilation cooling systems have direct cooling and indirect cooling.
When the ambient temperature is greater than 80 °C (such as heating furnaces, steel-making furnaces, etc.), the forced-air cooling system can be used when the temperature rise cannot be controlled by forced air cooling. The thermal conductivity and specific heat of water are both greater than that of air. Therefore, compared with air cooling, the thermal resistance of the relevant heat exchange steps is greatly reduced, and the heat exchange efficiency is improved. The shroud contains a built-in water jacket that effectively isolates the camera and lens from the outside environment. Depending on the application, the material can be aluminum or stainless steel. The hood is internally equipped with a fan to reciprocate the air in the hood to improve the heat transfer efficiency. There are two basic types of forced water cooling systems, one is water-cooled and dust-proof, and the structure is relatively simple. There is no alarm device and air filtration system, and the lens can use a fixed focus or zoom lens for 80°C environment. The other is a high-temperature furnace type, which can be used in environments with temperatures up to 1600°C. The structure is relatively complex. The entire system has alarms, air filtration systems, maintenance shutters, and high-temperature automatic exit systems.
High-temperature automatic exit system When detecting the failure of the camera cooling function, the exit device of the electro-pneumatic control will automatically withdraw the camera from the combustion chamber to avoid damage to the camera and lens. The system normally starts when the following conditions occur: (1) The temperature of the cooling water at the top of the probe exceeds a predetermined value (≤ 40°C); (2) The compressed air fails or the pressure drops to a predetermined value (≤ 0.4Mpa); (3) The air hole at the probe cleans or fails Drop to a predetermined value (≤ 0.02 MPa); (4) Water flow less than a predetermined value (≤ 6.8 L/min); (5) Air or water monitoring line interruptions; (6) Mains voltage failure; (7) The control device or control center room issues an exit command.
The semiconductor cooling system, also called thermoelectric cooling, is a cooling method based on several different semiconductor effects. When two different conductors form a galvanic couple, when they are supplied with a direct current, the endothermic and exothermic phenomena occur at the corresponding joints of the couple. This effect is very much in metal and more pronounced in semiconductors. The semi-conductor refrigeration has no mechanical rotation part, has the characteristics of no noise, no vibration, long life, simple structure, easy installation, high reliability, does not require coolant, the degree of cooling can be adjusted according to the current, its disadvantage is greater consumption law DC power must be used and the operating current is large.
It has multi-function design with waterproof and dustproof.
Ventilated mesh body material difficult combustion-grade ABs resin. Has the anti - ultraviolet summer static electricity special effects. The filter material is made of imported nylon fiber synthetic resin, and the dust removal rate is up to 86% effectively to prevent dust from entering the electric control cabinet.
Ensure effective cooling of controller and precision electronic parts. Extended service life. Reduce the failure rate.
The filter should be cleaned regularly. To maintain ventilation filtering effect.
The protection level is IP44.
Ventilator Filter Unit 150, Ventilator Filter Unit 205, Ventilator Filter Unit 256, Ventilator Filter Unit 800
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