The present application is based on and claims propriety of Japanese patent application No. 2007-080453 filed on Mar. 27, 2007, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a train communication system suitable for information communication in trains.
2. Description of the Related Art
In recent years, needs have grown for the passenger information services using a liquid crystal display and the like in trains, and technologies for delivering various service contents from a server installed in a train to display units and the like in each of the cars have become widely available.
In the conventional technology described in Japanese Patent Laid-Open Publication No. 2002-209193, a train information device that processes train information such as train operation information including stop station information, arrival time, and the like, train location information indicating kilometers from the starting station, and train-mounted apparatus information including door open-close instruction and the like is installed in each of the cars. The train information device of the lead car is connected to various control operation devices such as a master control unit, and the train information devices installed in the cars are connected to each other through a digital transmission path, working in concert with each other to input and output the various train information.
An image information delivery device installed in the lead car is connected to the train information device in the same car, and receives train information and outputs still image information. The still image information is outputted as digital data signals through a first transmission path connecting the train information devices, then goes through the train information device installed in each of the cars, and is transmitted to a receiver/display device installed in each of the cars. The image information delivery device is connected to the receiver/display device installed in each of the cars through a second transmission path connecting the image information delivery devices and transmits moving image information as analog data signals.
As for the still image information having a smaller data size compared to the moving picture information, high-resolution still image information is digitally transmitted by a packet system which has been conventionally used in the train information device. On the other hand, the moving picture information having a larger data size than the still image information is transmitted by an analog transmission system such as an NTSC system which has been conventionally used in a television set and the like, enabling a train-mounted image delivery display system that realizes moving images and high-quality still images at low cost. In addition, because a system is employed that transmits the moving image information and the still image information to the receiver/display device via different paths, even if abnormality occurs in either one of the transmission paths, image information by moving images or still-images can be continuously displayed using the normal transmission path, so that the reliability of the display function is improved.
However, in the conventional technology described in Japanese Patent Laid-Open Publication No. 2002-209193, when transmitting the moving picture information as analog data signals, a considerably wide communication frequency band is required to transmit high-quality images. Because a plurality of cars are connected in a train, signal degradation occurs even if, for example, the analog signals are amplified and relayed using an amplifier or the like. In addition, because electro-magnetic noise generated by an inverter or the like installed in a train is superimposed on the analog signals, delivery of high-quality images to each of the cars is difficult.
When delivering images by analog data signals, multi-channel communication in which a plurality of pieces of moving image information or audio lines of a telephone and the like are multiplexed is provided in one transmission path, so that further wider frequency band is required which is difficult to realize. In addition, disconnection of a transmission line between cars or failure of a communication device in a train prevents transmission of the moving image information or the still image information to the display unit such that the information cannot be displayed.
An object of the present invention is to easily realize transmission of high-quality moving image information and audio information by digital data signals, and to reduce the influence of disconnection of a transmission line or failure of a communication device, thereby providing a highly reliable communication system in trains.
In order to achieve the object, a communication system in trains according to the present invention transmits a plurality of image data from a server to a display unit through an image data communication device, stores the image data in the display unit, and controls the screen display of the plurality of image data stored in the display unit by using control information transmitted from a control data communication device through the image data communication device.
According to the present invention, moving image information, still image information, and the like that are converted into digital data are transmitted by the image data communication device, and the image data communication device and the server or the control data communication device are separated. Therefore, even when the image data communication device is unable to communicate due to failure or other reasons, train control information transmitted by the server or the control data communication device allows to change display on the screen using the plurality of image data prestored in the display unit, so that the reliability of the system is enhanced.
Embodiments of a communication system in trains according to the present invention will now be described with reference to the drawings.
First Embodiment
A first embodiment of the present invention will be described with reference to
As shown in
A server 100 is installed in the first car and is connected to the image data communication device 300. The image data such as moving image information and still image information for transmission by the image data communication device 300, audio data for audio announcement, and other data are recorded in the server 100. The image data and audio data are transmitted to each of the cars using the image data communication device 300. As in other apparatuses, Ethernet or the like is used as an interface between the server 100 and the image data communication device 300.
A plurality of image data are transmitted from the server 100 to the display unit 200 using the image data communication device 300 and stored in the display unit 200. The display unit 200 displays one of the plurality of stored image data on the screen of the display unit in accordance with the train control information indicative of display timing transmitted by the control data communication device 400. Incidentally, more than one car may be equipped with the server 100.
The image data communication device 300 can transmit not only the image data, but also data such as audio information for in-train announcement, textual information for caption display, or operation log information of train-mounted apparatuses, as long as the data is digitized.
The control data communication device 400 is installed in need of transmitting the train operation information indicating a stop station and the like, the train location information indicating a travel distance from the starting point, and instruction information for controlling opening and closing of the door and the like, thereby conducting the highly reliable communication for realizing safe operation of the train. The control data communication device 400 is installed in an existing train and a new train as a communication device that conducts communication of the control data of train-mounted apparatuses with priority over the data such as the image data or the like that is not directly related to the train operation. In addition, the control data communication device 400 and the image data communication device 300 are provided separately.
As shown in
The control unit 302, of the image data communication device 300, connected to the control data communication device 400 through the transmission path 320 controls the modem 301 and the hub 303 to conduct data communication. Installation of the control unit 302 enables to control the packet transmission process in the hub 303.
The transmission path 310 is branched in the image data communication device 300 and is connected to the modem 301. Between the image data communication devices 300, communication is conducted in the multi-drop system in which one transmission path is shared. As an access system for executing the multi-drop system, a polling system, a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) system, or the like is employed.
When communicating in the multi-drop system, a wiring method of the transmission path 310 includes a method in which the transmission path 310 is branched outside the image data communication device 300 and connected at one point. In this case, the branch line length of the transmission path 310 depends heavily on the installation locations of the image data communication device 300 in the train and the branch point, so that the communication performance in the modem 301 may be greatly deteriorated. Therefore, in the present embodiment, as shown in
The control data communication device 400 is connected to the image data communication device 300 by an interface, such as RS-485, RS-232C, or TTL, that can be interconnected with the image data communication device 300. If they can mutually communicate, addition of the image data communication device 300 to the control data communication device 400 installed in an existing train or to the control data communication device 400 newly installed in a new train enables to easily establish the communication system in trains, and the cost for establishing the system can be reduced.
An example of the connection method of the transmission path 310 and the image data communication device 300 includes, as shown in
As shown in
The display unit 200 communicates with the image data communication device 300 in accordance with the Ethernet protocol, for example. Using the image data communication device 300, a plurality of image data are transmitted from the server 100 to the memory 202 of the display unit 200 and stored in the memory 202. In the display unit 200, the controller 201 displays either the plurality of image data or the textual information for caption display that are stored in the memory 202 onto the screen 203, in accordance with the control data transmitted by the control data communication device 400.
One example of display of the screen 203 of the display unit 200 is illustrated in
The timing information 411 for image display is transmitted from the control data communication device 400 to the display unit 200 through the image data communication device 300. The timing information 411 includes kilometers indicating the travel distance from the starting point, passed station names, time information, or the like.
If the image data communication device 300b has failed, communication cannot be conducted between the image data communication device 300a and the image data communication device 300c, so that the new image data 311 cannot be transmitted from the server 100 to the display unit 200c. However, because the plurality of image data are already stored in the memory 202 of the display unit 200, the screen 203 of the display unit 200c can be switched by obtaining the timing information 411 from the control data communication device 400c.
As described, according to the present embodiment, the plurality of pieces of moving image information, audio information, textual information, log information of train-mounted apparatuses, and the like are converted into digital data signals to conduct multiplexed communication with one channel, allowing high-quality moving image transmission and audio transmission to each of the cars. Transmission by digital data signals in combination with an error correction coding technology and a retransmission technology enables to establish a highly reliable system.
Second Embodiment
A second embodiment of the present invention will be described with reference to
Third Embodiment
A third embodiment of the present invention will be described with reference to
Fourth Embodiment
A fourth embodiment of the present invention will be described with reference to
The wireless communication device 610a transmits data such as new moving image information, still image information, audio information, and textual information from a base station server 620 in a ground base station 600 placed on the ground through a wireless communication device 610b, thereby allowing to change the display of the screen 203 of the display unit 200.
In the communication system in trains described in the first embodiment, the wireless communication device 610a may be installed in the first car, and the wireless communication device 610a may be connected to the image data communication device 300.
Fifth Embodiment
A fifth embodiment of the present embodiment will be described with reference to
However, the wireless communication device 610a installed in the first car is connected to the image data communication device 300. Thus, the wireless communication device 610a can transmit data such as new moving image information, still image information, audio information, and textual information from the base station server 620 in the ground base station 600 placed on the ground through the wireless communication device 610b, and can transmit the control information indicative of the display timing together with the image data 311 from the server 100 through the image data communication device 300, thereby allowing to change the display of the screen 203 of the display unit 200.
As described, the communication device in trains of the embodiments transmits the plurality of image data, textual information for caption display, and the like from the server 100 to the display unit 200 through the image data communication device 300 and transmits the timing information from the server 100 or the control data communication device 400 to the display unit 200 through the image data communication device 300, enabling to establish a highly reliable communication system in trains whose display on the screen of the display unit 200 can be switched, even when the image data communication device 300 has failed.
Number | Date | Country | Kind |
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2007-080453 | Mar 2007 | JP | national |
Number | Name | Date | Kind |
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6453071 | Ito et al. | Sep 2002 | B2 |
6948022 | Ishibashi | Sep 2005 | B2 |
6970168 | Emoto et al. | Nov 2005 | B2 |
7391317 | Abraham et al. | Jun 2008 | B2 |
20060170285 | Morimitsu et al. | Aug 2006 | A1 |
Number | Date | Country |
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2002-209193 | Jul 2002 | JP |
2004-203338 | Jul 2004 | JP |
2005-057524 | Mar 2005 | JP |
Entry |
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Machine English Translation of JP 2002-209193 A, Translated date Mar. 9, 2011. |
Number | Date | Country | |
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20080237406 A1 | Oct 2008 | US |