JP5008493B2 - Explosion-proof network camera and image transmission system in hazardous area - Google Patents

Description

  The present invention relates to an explosion-proof network camera capable of transmitting image data taken in a dangerous area through a wireless local area network (LAN), and an image transmission system in the dangerous area using such an explosion-proof network camera.

  For example, in refineries and petrochemical factories, non-hazardous areas are used to perform business management and maintenance of manufacturing equipment in hazardous areas where flammable gases or flammable liquid vapors may exist. In addition, a management facility is provided in the center, and various data are transmitted and received between the management facility and various facilities installed in the hazardous area for centralized management.

And when performing transmission and reception of such data, it is desired to transmit image data taken for monitoring the situation at the site to the management facility. For example, Patent Document 1 Explosion-proof surveillance cameras used in hazardous atmospheres have been proposed.
Japanese Patent Laid-Open No. 11-80605

  By the way, the explosion-proof surveillance camera of Patent Document 1 has an explosion-proof structure to prevent the explosion and fire caused by the camera, and the focus adjustment is possible without directly touching the camera even in a hazardous atmosphere. Although it has been devised, it does not have various functions such as a zoom function, a pan function, and a tilt function. For this reason, the explosion-proof surveillance camera of Patent Document 1 is fixed, and operations such as image zooming, horizontal operation (panning) and vertical operation (tilting) of the camera cannot be performed.

  Moreover, the image output from the explosion-proof surveillance camera of patent document 1 is based on an analog signal. For this reason, in order to transmit the signal to the management facility, it must be wired with a coaxial cable, and even if it is equipped with the above functions and can be operated from a remote location, a special remote operation signal is used for image transmission. It was necessary to transmit using a cable different from the communication cable.

On the other hand, in recent years, wireless LAN has attracted attention for data transmission / reception between a management facility in a non-hazardous area and various facilities installed in the hazardous area. According to the wireless LAN, it is not necessary to install a communication cable, which is advantageous in terms of cost.
However, in order to transmit image data captured by the surveillance camera of Patent Document 1 via a wireless LAN, an analog signal must be converted into a digital signal. For this purpose, an encoder which is a digital signal converter needs to have an explosion-proof structure, but at present, an explosion-proof encoder has not been realized.

In recent years, so-called network cameras that can be easily connected to a wireless LAN communication system have become popular. Some of these network cameras have various functions such as a zoom function, a pan function, and a tilt function, and can be remotely operated from an operation terminal connected to the network. Therefore, it is conceivable to use a network camera as an intrinsically safe explosion-proof structure and transmit image data taken in a dangerous area via a wireless LAN.
However, in order to avoid the explosion of flammable gas, flammable liquid vapor, etc. in the hazardous area, there is a problem that it is difficult to make the drive mechanism for zooming, panning, tilting, etc. explosion-proof.

In addition, although risk areas in refineries and petrochemical plants are generally wide, it is difficult to secure a sufficient wireless LAN relay distance with existing facilities. For this reason, in order to transmit image data via a wireless LAN from a dangerous area that is considerably distant from the management facility in the non-hazardous area, the image data must be transmitted via a plurality of repeaters.
However, in this case, the transmission capacity decreases every time relaying is performed, and the decrease in transmission capacity becomes more remarkable as the number of repeaters increases. Therefore, there is a problem that large-capacity data such as image data is difficult to relay over a long distance using a wireless LAN.

  The present invention has been made in view of the above circumstances, and an explosion-proof network camera capable of transmitting image data taken in a hazardous area such as a refinery or a petrochemical factory via a wireless LAN, and such an explosion-proof network. The purpose is to provide an image transmission system in hazardous areas using cameras.

The explosion-proof network camera used in the image transmission system according to the present invention has a pressure-proof explosion-proof structure and houses a network camera having a network function in a housing having a dome-shaped housing portion formed of a transparent pressure-resistant material. In addition, the camera module of the network camera is configured to be positioned in the dome-shaped housing portion.

With such a configuration, it is possible to directly connect to the network and transmit image data taken in the dangerous area to, for example, a wireless LAN server installed in the non-hazardous area.

Further, explosion-proof network camera, at least zooming, panning, or by a structure that includes a single function of the tilt function, by the connected operating terminal on the network, image zoom, the horizontal operation of the camera (Pan) and up / down movement (tilt) can be operated remotely.

In the image transmission system according to the present invention using such an explosion-proof network camera, a wireless LAN bidirectional communication unit for performing bidirectional communication by wireless LAN is housed in a first casing having a pressure-proof explosion-proof structure, The antenna main body, which is a directional antenna, is connected to the wireless LAN bidirectional communication unit by an antenna cable that extends outside the first housing while maintaining the explosion-proof structure. A radio wave transmitting material that transmits signals is used for at least a part, and the antenna body is housed in a second casing having a pressure-proof explosion-proof structure while maintaining the pressure-proof explosion-proof structure. At least a pair of wireless LAN explosion-proof repeaters installed in a dangerous area and a pair of wireless LAN explosion-proof relays installed in a non-dangerous area A wireless LAN server connected to one of them, and an explosion-proof construction connected to the other or both of the pair of wireless LAN explosion-proof repeaters installed in the hazardous area, and made of a transparent pressure resistant material. An explosion-proof network camera in which a network camera having a network function is housed in a housing having a formed dome-shaped housing portion, and the camera module of the network camera is positioned in the dome-shaped housing portion. It is as a configuration.

According to the image transmission system of the present invention configured as described above, when transmitting image data from the explosion-proof network camera in the dangerous area to the wireless LAN server in the non-hazardous area, a pair of wireless LANs installed in the dangerous area A long distance can be relayed wirelessly by an explosion-proof repeater. At this time, since a sufficient relay distance can be secured without interposing a plurality of repeaters, it is possible to transmit / receive large-capacity data to / from a remote location without reducing the transmission capacity. Image data can be transmitted from a remote location to a wireless LAN server without any trouble. In particular, by using a directional antenna for the antenna body, a long-distance wireless relay of about 1,000 m at maximum is possible.

  In the image transmission system according to the present invention, the camera module of the network camera has at least one of a zoom function, a pan function, and a tilt function, and can be remotely operated by an operation terminal connected by a wireless LAN. With this configuration, it is possible to remotely control image zooming, camera horizontal movement (panning), vertical movement (tilting), and the like with an operation terminal connected to the network.

As described above , according to the image transmission system of the present invention, when transmitting image data from the explosion-proof network camera in the dangerous area to the wireless LAN server in the non-hazardous area, a pair of wireless LAN explosion-proof installed in the dangerous area. By using a type repeater, long distances can be relayed wirelessly. At this time, a sufficient relay distance can be secured without interposing multiple repeaters. It is possible to transmit and receive large-capacity data on the Internet and transmit large-capacity image data from a remote location to the wireless LAN server without any trouble.

  Hereinafter, preferred embodiments of the present invention will be described.

[Explosion-proof network camera]
First, an embodiment of an explosion-proof network camera used in the image transmission system according to the present invention will be described.
1A and 1B are explanatory views showing an outline of an embodiment of an explosion-proof network camera used in an image transmission system according to the present invention. FIG. 1A is a front view and FIG. 1B is a plan view.

The explosion-proof network camera 1 shown in FIG. 1 houses a network camera 20 in a casing 10 having a pressure-proof explosion-proof structure.
The housing 10 includes a main body part 11, a lid part 12, and a dome-shaped accommodation part 13. These members are fixed in a state where they are pressed against each other via a sealing member such as a gasket, and the casing 10 is a fully closed container having a pressure-proof explosion-proof structure.

  In the illustrated example, the main body 11 is formed as a bottomed cylindrical metal member. The lid portion 12 is a lid-shaped metal member that covers the opening of the main body portion 11, and is fixed to the main body portion 11 by tightening bolts 14 that are arranged at substantially equal intervals along the periphery.

  Further, the main body 11 is provided with cable joints 111 and 112 for extending the cable from the inside to the outside of the housing 10 while maintaining the explosion-proof structure. The cable joints 111 and 112 are internally provided with sealing means such as cable packing made of a rubber cylindrical member, and can be sealed in a state where the cable is inserted.

  Moreover, the dome-shaped accommodation part 13 is attached above the lid body 12 so as to protrude in a dome shape. The dome-shaped accommodation portion 13 can be formed of a transparent pressure resistant material such as pressure resistant transparent glass, for example. Although not particularly illustrated, the dome-shaped storage portion 13 is formed, for example, by forming a flange portion projecting horizontally on the lower end side thereof, and pressing the flange portion to the inner surface side of the lid body 12 via a sealing member. You can fix it.

  In the present embodiment, the network camera 20 is housed in such a casing 10. The network camera 20 is a camera that itself has a network function and can be directly connected to the network.

  As shown in FIG. 2, the network camera 20 generally captures an image with a camera module 21, which includes one or a plurality of lenses held in a lens barrel and an image sensor such as a CCD or a CMOS as basic components. An encoder 22 that digitizes the video of the subject and converts it into image data, a compression conversion unit 23 that compresses and encodes the image data converted by the encoder 22, a network communication unit 24 that sends out the compression-encoded image data, and necessary A power supply unit 25 that supplies power is provided.

  FIG. 2 is a block diagram illustrating the configuration of a general network camera. Here, the transmission cable 26 connected to the network communication unit 24 extends from the cable joint 111 of the housing 10 to the outside of the housing 10 and is connected to a network communication device such as the switching hub 90 (a diagram described later). 3). The power cable 27 connected to the power supply unit 25 extends from the cable joint 112 of the housing 10 to the outside of the housing 10 and is connected to a predetermined power supply source.

  In the present embodiment, the network camera 20 is accommodated in the housing 10 such that the camera module 21 is positioned in the dome-shaped accommodating portion 13. At this time, a wide photographing range can be ensured by designing the dome-shaped accommodation portion 13 in consideration of the shape and size of the camera module 21.

  Furthermore, the network camera 20 preferably has at least one of a zoom function, a pan function, and a tilt function. In this case, when the camera module 21 is positioned in the dome-shaped housing portion 13, the camera module 21 that moves with the above functions is maintained by keeping the distance between the inner surface side of the dome-shaped housing portion 13 and the camera module 21 constant. Interference with can be avoided.

  The explosion-proof network camera 1 as described above has an image signal digitized, and is directly connected to the network, for example, applied to an image transmission system described later, such as a refinery or a petrochemical factory, A wireless LAN server 101 installed in a management facility 100 such as a measurement room or office in a non-hazardous area captures image data taken in a dangerous area where flammable gas or vapor of flammable liquid may exist. Can be transmitted. It is also possible to remotely operate image zooming, camera horizontal movement (panning), vertical movement (tilting), etc. by terminal operation from the wireless LAN server 101 connected to the network.

[Image transmission system in hazardous areas]
Next, an embodiment of an image transmission system in a hazardous area according to the present invention will be described.

FIG. 3 is a block diagram showing an outline of an embodiment of an image transmission system in a hazardous area according to the present invention.
The image transmission system according to the present embodiment is photographed by an explosion-proof network camera 1 installed in a dangerous area where there is a possibility that flammable gas, vapor of flammable liquid, etc. may exist, such as a refinery or a petrochemical factory. The transmitted image data is transmitted to a wireless LAN server 101 installed in a management facility 100 such as a measurement room or office in a non-hazardous area by wireless LAN.

  The explosion-proof network camera 1 installed in the dangerous area and the wireless LAN server 101 installed in the non-hazardous area are a pair of wireless LAN explosion-proof repeaters 5a and 5b installed at a certain distance in the dangerous area. Therefore, the communication in the dangerous area is relayed wirelessly, and the laying of the communication cable between them is unnecessary.

As the wireless LAN explosion-proof repeater 5 (5a, 5b), for example, the one shown in FIG. 4 can be used.
The wireless LAN explosion-proof repeater 5 shown in FIG. 4 includes a wireless LAN bidirectional communication unit 60 that performs bidirectional communication by wireless LAN and a power supply unit 80 that supplies necessary power in a first housing 51. It is housed.

The first housing 51 can be a metal fully closed container having a flameproof structure and made up of a container body and a lid.
The first casing 51 is provided with cable joints 511, 512, and 513 for maintaining the explosion-proof structure and extending the cables outside the first casing 51. These cable joints 511, 512, and 513 are provided with sealing means such as cable packing made of a rubber cylindrical member, for example, and can be sealed in a state where the cable is inserted.

An antenna main body 90 is connected to the bidirectional communication unit 60 accommodated in the first casing 51 by an antenna cable 91 extended from the cable joint 511 to the outside of the first casing 51.
Similarly, the power cable 81 connected to the power supply unit 80 extends from the cable joint 513 to the outside of the first housing 51.
In the illustrated example, power is supplied by the PoE (Power over Ethernet / “Ethernet” is a registered trademark) method, and the bidirectional communication unit 60 and the power supply unit 80 are connected by the PoE power supply cable 68. Has been. The communication cable 61 such as an optical cable is connected to the power supply unit 80 and extends from the cable joint 512 to the outside of the first casing 51. Thereby, as shown in FIG. 3, the wireless LAN explosion-proof repeater 5 can be connected to the wireless LAN server 101 by connecting the communication cable 61 to the switching hub 102.

The specific configuration of the wireless LAN bidirectional communication unit 60 is not particularly limited as long as the wireless LAN bidirectional communication unit 60 can perform bidirectional communication by wireless LAN based on a LAN signal transmitted and received by the antenna body 90. For example, in accordance with a communication standard such as IEEE 802.11, bidirectional communication by a wireless LAN between a pair of wireless LAN explosion-proof repeaters 5a and 5b, both by a wired LAN or a wireless LAN with a wireless LAN server 101 It is only necessary to be able to realize bidirectional communication and further bidirectional communication with the explosion-proof network camera 1.
In addition, the wireless LAN bidirectional communication unit 60 includes an optical / electrical converter that mutually converts an optical signal and an electrical signal so that communication can be performed using either the optical signal or the electrical signal. You can also.

On the other hand, the antenna main body 90 connected to the wireless LAN bidirectional communication unit 60 by the antenna cable 91 is housed in the second casing 52 having the explosion-proof structure so that the explosion-proof structure is maintained. Yes.
The second casing 52 shown in FIG. 4 is provided with a cable joint 523 similar to the cable joints 511, 512, and 513 provided in the first casing 51. The antenna cable 91 is drawn into the second casing 52 by the cable joint 523 so that the explosion-proof structure of the second casing 52 is maintained, and the antenna cable 91 is connected to the antenna body 90. .

The second casing 52 includes a radio wave transmitting member 521 made of a radio wave transmitting material that transmits a radio wave signal (LAN signal) transmitted and received by the antenna main body 90, and a metal base 522. As a radio wave transmitting material for forming the radio wave transmitting member 521, a material capable of suppressing transmission loss of radio wave signals is appropriately selected.
The radio wave transmitting member 521 can be formed as a cylindrical member whose one end is closed so as to cover the periphery of the antenna body 90. Then, the antenna main body 90 is inserted through the opening on the other end side of the radio wave transmitting member 521, and the opening of the radio wave transmitting member 521 is closed by the base 522 to which the base of the antenna main body 90 is fixed. The second casing 52 has a flameproof structure.

The antenna body 90 is a directional antenna with high directivity.
As the directional antenna, for example, an 8-element Yagi type can be used.

  In the wireless LAN explosion-proof repeater 5 as described above, the antenna main body 90 is accommodated alone in the second casing 52 having a pressure-proof explosion-proof structure, and the installation position of the antenna main body 90 is oriented to the antenna main body 90. It can be freely determined according to gender. For this reason, in particular, by using a directional antenna for the antenna body 90, it is possible to perform wireless relay over a long distance of up to about 1,000 m.

In the example shown in FIG. 3, a communication cable 61 such as an optical cable is laid from a non-hazardous area to a dangerous area. With this communication cable 61, one wireless LAN explosion-proof repeater 5a installed in the dangerous area The wireless LAN server 101 installed in the management facility 100 is connected via the switching hub 102. The explosion-proof network camera 1 is connected to the other wireless LAN explosion-proof repeater 5b via an explosion-proof switching hub 70.
Here, as the explosion-proof switching hub 70, for example, the explosion-proof switching hub proposed in Japanese Patent Application No. 2006-142110 filed earlier by the present applicant can be used.

As described above, in the image transmission system according to the present embodiment, when transmitting image data from the explosion-proof network camera 1 in the dangerous area to the wireless LAN server 101 in the non-hazardous area, a pair of wireless devices installed in the dangerous area. The LAN explosion-proof repeaters 5a and 5b can relay a long distance wirelessly. And according to this embodiment, since a sufficient relay distance can be secured without interposing a plurality of repeaters, large-capacity data can be transmitted to and received from a remote place without reducing the transmission capacity. It becomes possible. Therefore, a large amount of image data can be transmitted from the remote place to the wireless LAN server 101 without any trouble.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Nor.

For example, the wireless LAN explosion-proof repeaters 5a and 5b can be connected to various network communication devices such as a wireless LAN access point having a pressure-proof explosion-proof structure via the explosion-proof switching hub 70 as described above. it can. The wireless LAN access point is wirelessly connected to a transceiver such as a computer to which a wireless LAN adapter is attached and a PDA (Personal Digital Assistant) having a transmission / reception function.
These devices have an explosion-proof construction so that they can be used in hazardous areas. For example, as an explosion-proof wireless LAN access point, proposed in Japanese Patent Application No. 2005-8297 filed earlier by the present applicant. The wireless LAN explosion-proof repeater or the wireless LAN explosion-proof repeater proposed in Japanese Patent Application No. 2006-142110 can be used.

In the above-described embodiment, the wireless LAN explosion-proof repeater 5a and the wireless LAN server 101 are connected by the wired LAN with the communication cable 61. However, the wireless LAN explosion-proof repeater 5a and the wireless LAN server 101 are connected. The connection may be made by either a wired LAN or a wireless LAN.
When the wireless LAN explosion-proof repeater 5a and the wireless LAN server 101 are connected by a wireless LAN, a wireless LAN adapter connected to the wireless LAN server 101 is installed on the non-hazardous area side. Since the wireless LAN adapter installed in the non-hazardous area does not need to have a pressure-proof explosion-proof structure, various non-explosion-proof wireless LAN adapters can be used. On the other hand, it is necessary to provide an explosion-proof wireless LAN access point for connecting with a wireless LAN adapter installed in a non-hazardous area via a wireless LAN on the dangerous area side. As such a wireless LAN access point, for example, a wireless LAN explosion-proof repeater proposed in Japanese Patent Application No. 2005-8297 filed earlier by the present applicant, or a wireless LAN explosion-proof repeater proposed in Japanese Patent Application No. 2006-142110. Etc. can be used.

Further, a plurality of wireless LAN explosion-proof repeaters are additionally installed between the pair of wireless LAN explosion-proof repeaters 5a and 5b installed in the hazardous area, and two wireless LAN explosion-proof repeaters 1 are installed. As a pair or more, the entire relay distance can be extended.
For example, two wireless LAN explosion-proof repeaters can be additionally installed between the pair of wireless LAN explosion-proof repeaters 5a and 5d so as to be paired with the wireless LAN explosion-proof repeaters 5a and 5d. . At this time, the added wireless LAN explosion-proof repeaters may be connected by either a wired LAN or a wireless LAN.
In addition, the installation location of the wireless LAN explosion-proof repeater added between the pair of wireless LAN explosion-proof repeaters 5a and 5b may be a non-dangerous district adjacent to the dangerous district. In this case, the wireless LAN explosion-proof repeater to be added may be installed with a pressure-proof explosion-proof structure, but the first and second casings 51 and 52 may be omitted to be a non-explosion-proof type.

  In addition, the wireless LAN explosion-proof repeater 5 is connected to various network communication devices via the explosion-proof switching hub 70. The switching hub 70, together with the bidirectional communication unit 60, is included in the first casing. A configuration accommodated in 51 is also possible.

  The present invention is not limited to plants such as refineries and petrochemical plants, but can be effectively applied to the entire equipment industry that requires explosion-proof equipment including food industry and steel industry. it can.

It is explanatory drawing which shows the outline of embodiment of the explosion-proof type network camera utilized in the image transmission system which concerns on this invention. It is a block diagram which shows the outline of 1st embodiment of the image transmission system which concerns on this invention. It is a block diagram which shows the outline of 2nd embodiment of the image transmission system which concerns on this invention. It is a block diagram which shows the outline of 3rd embodiment of the image transmission system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Explosion-proof type network camera 10 Case 20 Network camera 5 (5a, 5b) Wireless LAN explosion-proof type repeater 51 First case 52 Second case 521 Radio wave transmission member 522 Base 60 Two-way communication unit 90 Antenna body 91 Antenna cable 100 Management facility 101 Wireless LAN server

Claims (2)

A wireless LAN bidirectional communication unit that performs bidirectional communication by wireless LAN is accommodated in a first casing having a pressure-proof explosion-proof structure, and is extended outside the first casing while maintaining the pressure-proof explosion-proof structure. An antenna cable connects the antenna body, which is a directional antenna, to the wireless LAN bidirectional communication unit, and at least a part of a radio wave transmitting material that transmits radio signals transmitted and received by the antenna body is used. In the second casing having a structure, the antenna body is accommodated while maintaining the explosion-proof structure, and at least a pair of wireless LAN explosion-proof repeaters that are installed in a hazardous area at a certain distance;
A wireless LAN server installed in a non-hazardous area and connected to one of the pair of wireless LAN explosion-proof repeaters;
Installed in a hazardous area, with a flameproof construction that is connected to the other or both of the pair of wireless LAN explosion-proof repeaters, and having a dome-shaped housing portion formed of a transparent pressure-resistant material An explosion-proof network camera in which a network camera having a network function is housed, and the camera module of the network camera is located in the dome-shaped housing portion;
An image transmission system comprising: 2. The image transmission system according to claim 1 , wherein the camera module of the network camera has at least one of a zoom function, a pan function, and a tilt function, and can be remotely operated by an operation terminal connected by a wireless LAN. .

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