Signal transmission cable and cable connection state confirmation method in wiring box

Abstract

To provide a signal transmission cable which can shorten time required for connection confirmation work without greatly increasing cost.SOLUTION: A signal transmission cable in which the periphery of one or two or more signal lines capable of transmitting an electric signal or an optical signal is coated with a sheath or a skin, and connection components (connectors) are provided on both ends includes a pair of terminals for inspection provided on base parts of the connection components so as to be exposed to the outer peripheral surface of the sheath or the skin, wherein the terminals for inspection are electrically connected to a linear conductor which is provided in the sheath or between the signal line and the skin and extends in a cable axial direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a signal transmission cable having connectors on both ends and a method for checking the cable connection status in a distribution box, and more particularly to a technology useful for a protected optical cable having a protective layer made of metal such as stainless steel around an optical fiber core and a method for checking the cable connection status in a distribution box using the same. [Background technology]

[0002] Along railway tracks, multiple cables are laid to transmit information between wayside facilities and equipment that constitute railway safety systems, such as ground coils and signals, and various control devices installed in stations. In recent years, with the increase in the amount of information to be transmitted, optical cables having optical fiber cores are used for information transmission cables along railway tracks, and one end of the optical cables is collected in an equipment room installed in the station premises and connected to an optical distribution box installed inside.

[0003] The optical distribution box is provided with multiple trays containing multiple relay connectors or connector terminals that connect multiple optical connectors together, and the optical cables are connected to each other or to optical fiber cords by the optical connectors in the trays. Here, the information transmitted by the optical cables collected in the optical distribution box includes information to be transmitted to devices and equipment in other stations as well as a wide variety of devices and equipment installed in the station. Therefore, a large number of optical cables are collected in one optical distribution box, and many optical fiber cords are connected to the relay connectors or connector terminals in the trays in order to properly distribute the information destinations in the optical distribution box. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-203580 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, when new equipment or devices are installed or when improvements are made to cable extension facilities, a continuity test is performed to check whether the optical fiber cords connected to the optical distribution box are connected correctly. Moreover, this test is sometimes performed while the line is live so as not to disrupt train operations. However, while a continuity test can be performed by pulling out the connector of the optical fiber cord from the optical distribution box when the line is not live, the connector of the optical fiber cord cannot be pulled out when the line is live. In addition, as described above, many optical cables and optical fiber cords are connected to the optical distribution box, so it is difficult to visually check whether each cord is connected correctly.

[0006] Therefore, in the past, such connection checks required manual tracing of each optical fiber cord, which resulted in a problem of the time required for the connection check work.In addition, optical fiber cords that are simply coated with an outer jacket around a quartz glass optical fiber core are prone to breakage, so there was a risk of the optical fiber cord being damaged during the connection check work. There have also been accidents in which optical fiber cords have been damaged by being chewed by small animals such as mice. Therefore, in recent years, protective optical fiber cords in which a metal such as stainless steel is wrapped around the optical fiber core have come into use. Although the use of protective optical fiber cords can reduce the risk of damaging the optical fiber cord, the problem of the time required for connection check work remains.

[0007] Meanwhile, conventionally, as a device having a function similar to that of an optical distribution box, there is a subrack that is composed of a housing, a front panel section provided on the front side of the housing, and a card made of a plurality of optical circuit boards and the like housed in the housing. An optical fiber connection section is provided on the front panel section of this subrack, and an optical connector of an optical fiber cable is connected to this optical fiber connection section. Therefore, it is difficult to identify an optical fiber cord to be selected from a large number of wired optical fiber cords. Therefore, an invention has been proposed relating to an optical fiber cord that makes it easy to identify an optical fiber cord to be selected from a large number of optical fiber cords (see Patent Document 1).

[0008] The invention described in Patent Document 1 relates to an optical fiber cord that is made by providing an optical fiber core and a pair of conductors sandwiching the optical fiber core and covering them with a jacket, and providing light-emitting elements electrically connected to the pair of conductors at connectors at both ends of the optical fiber cord, and by supplying power from the connector at one end to cause the light-emitting elements at both ends to emit light, thereby making it possible to easily identify the connector of the optical fiber cord to be selected from among a large number of optical fiber cords. However, the invention of Patent Document 1 has a problem in that it requires providing a pair of conductors inside the optical fiber cord and providing light-emitting elements at both ends of the cord, which leads to an increase in costs.

[0009] An object of the present invention is to provide a signal transmission cable that can shorten the time required for connection confirmation work without incurring a significant increase in cost. Another object of the present invention is to provide a method for checking the cable connection status in an optical fiber cord (optical cable) and an optical distribution box, which can shorten the time required for the connection checking work and has a low risk of breakage during the connection checking work. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides A signal transmission cable in which one or more signal lines capable of transmitting electrical or optical signals are covered with a sheath or jacket and connecting parts are provided at both ends, a pair of inspection terminals provided at a base portion of the connection part so as to be exposed on an outer circumferential surface of the sheath or the outer cover, The inspection terminal is configured to be electrically connected to a linear conductor that is provided within the sheath or between the signal line and the outer cover and extends in the axial direction of the cable.

[0011] According to the signal transmission cable having the above-mentioned configuration, the inspection terminals at the bases of the connection parts (connectors) at both ends of the signal transmission cable are electrically connected to each other by a linear conductor extending in the axial direction of the cable. Therefore, by bringing the contacts of two lead wires extending from a tester into contact with the inspection terminals at the bases of the two connection parts identified as the connection parts (connectors) at the ends of the signal transmission cable to be inspected, it is possible to easily determine whether the signal transmission cable is correctly connected, and to shorten the time required for the connection check work.

[0012] Here, it is preferable that the signal line is an optical fiber core for transmitting an optical signal. If the signal line in the signal transmission cable is an optical fiber core, there is a risk that the optical fiber will be damaged during the work of checking the connection of the optical cable. However, with the above configuration, there is no need to manually search for the cable, so damage to the optical fiber core during the work can be avoided.

[0013] Also, preferably, the linear conductor is a protective layer made of a conductive metal formed so as to surround the one or more signal lines, the inspection terminal is a sleeve made of a conductive and plastically deformable material, The cable is configured so that one or more conductive wires are sandwiched between the inner surface of the sleeve and the outer surface of the outer jacket, with one end being in electrical contact with the protective layer and the other end being folded back in the axial direction of the cable and joined to the outer surface of the sheath or the outer jacket.

[0014] According to the above-mentioned configuration, a cable can be realized that utilizes a protective layer provided for rodent prevention measures, etc., to check whether the connecting parts (connectors) are connected correctly, thereby avoiding a significant increase in the cost of the cable.

[0015] Further, preferably, the protective layer is formed by winding a linear conductive metal spirally around the one or more signal lines, One end of the one or more conductive wires is configured to be inserted along a spiral groove in the protective layer. According to this configuration, the end of the conductive wire that electrically connects the inspection terminal and the protective layer can be relatively easily inserted between the protective layer and the sheath or the outer cover.

[0016] Another invention related to this application is 3. A cable connection state checking method for checking connection states of signal transmission cables in a distribution box in which a plurality of trays or boards, each having a plurality of relay connectors or connector terminals mounted thereon, are stored in a housing in a layered, vertical or matrix manner, and connection parts at both ends of a plurality of signal transmission cables according to claim 1 or 2 are connected to the relay connectors or connector terminals, respectively, comprising: A step of identifying two connection parts that are considered to be connection parts at the end of the signal transmission cable to be inspected by referring to a drawing or a list showing the connection relationship of the signal transmission cable; a step of bringing a contactor at an end of one of two lead wires extending from an inspection device into contact with the inspection terminal at a base of one of the two identified connection parts; a step of contacting the contactor of the other end of one of two lead wires extending from the inspection device with the inspection terminal at a base of the other of the two identified connection parts; and determining whether or not the signal transmission cable being inspected is connected correctly based on the presence or absence of sound or light emitted by the inspection device.

[0017] According to the above method, since there is no need to manually probe the cable in the connection checking work to check whether the connecting part (connector) at the end of the cable is correctly connected to the relay connector or the connector terminal, the time required for the checking work can be shortened. In addition, when the signal transmission cable is an optical fiber, there is an advantage that the optical fiber core wire can be prevented from being damaged during the work. Effect of the Invention

[0018] According to the present invention, it is possible to realize a signal transmission cable that can shorten the time required for connection check work without incurring a significant increase in cost. In addition, there is an effect that it is possible to realize an optical fiber cord (optical cable) that can shorten the time required for connection check work and has no risk of being damaged during the connection check work. [Brief description of the drawings]

[0019] [Figure 1] 1 is a side view showing an optical cable and an optical connector according to an embodiment of the present invention; [Diagram 2] FIG. 2A is a cross-sectional view showing an example of the structure of an optical cable according to an embodiment, and FIG. 2B is a cross-sectional view showing a modified example of the optical cable according to the embodiment. [Diagram 3] 1 is a partial cross-sectional view showing a configuration example of an end portion of an optical cable according to an embodiment; [Figure 4] 1 is a front view showing an example of a configuration of an optical distribution box in which optical cables are assembled and connected; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, with reference to the drawings, an embodiment of the signal transmission cable according to the present invention will be described as an example in which it is applied to an optical cable. Generally, an optical fiber cord is an optical fiber core (optical fiber strand) in which the surface of the optical fiber is covered with a plastic and protected by covering with an outer jacket, and an optical cable is an optical fiber cord in which multiple optical fiber cores are strengthened by using a covering called a protective sheath or a reinforcing material, but in this specification, the optical fiber cord is also included in the optical cable.

[0021] FIG. 1 is a side view showing an optical cable according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of the optical cable according to the embodiment. As shown in Fig. 1, an optical cable 10 according to this embodiment is provided with optical connectors 11 as connecting parts at both ends, and an inspection terminal 12 made of a conductive metal sleeve is provided at the base of the optical connector 11. Note that the optical connector 11 shown in Fig. 1 is an SC connector having a rectangular cross section, but it may also be an FC connector having a circular cross section. Note that in conventional optical cables, the inspection terminal 12 is not provided at the base of the optical connector 11.

[0022] The optical connector 11 includes a ferrule 11A that serves as a core for aligning the optical axes, a plug housing 11B that houses a plug frame that holds the ferrule 11A, and a boot 11C that is connected to the rear end side of the plug housing 11B. On the other hand, as shown in FIG. 2(A), the cable body of the optical cable 10 has an optical fiber core having the surface of the optical fiber 13 covered with an outer jacket 14 such as plastic, around which a protective layer 15 is provided by spirally winding a linear stainless steel material, and the outer periphery of the protective layer 15 is covered with a protective sheath or outer jacket 16 made of an insulating and heat-resistant resin.

[0023] Next, a detailed structure of the end of optical cable 10 of this embodiment equipped with inspection terminal 12 will be described with reference to Fig. 3. Fig. 3 is a partial cross-sectional view showing the configuration of the cable end in a state where optical connector 11 provided at the end of the optical cable shown in Fig. 1 has been removed. 3, in optical cable 10 of this embodiment, one end of two wires 17A, 17B made of a thin-diameter conductive material is inserted between protective layer 15 and outer jacket 16 at the end of the cable. This electrically connects wires 17A, 17B to protective layer 15. Then, the other ends of wires 17A, 17B are folded back toward the other end of the cable (to the right in the figure), and a conductive metal sleeve is fitted into the wires with the tips in contact with the surface of outer jacket 16, and inspection terminal 12 is formed by crimping using a tool.

[0024] Wires 17A, 17B may be formed by folding one wire in half to form two wires, or three or more wires may be bundled together. When folding one wire in half or bundling three or more wires, it is preferable to twist the end of the wire on the insertion side. When one end of wire 17A, 17B is inserted between protective layer 15 and outer cover 16, if protective layer 15 is made of a spirally wound stainless steel material, a spiral groove is formed on the surface of protective layer 15, and the end of wire 17A, 17B may be inserted along the groove.

[0025] For the wires 17A and 17B, for example, SUS304 stainless steel wire with a diameter of about 0.07 mm may be used. For the metal sleeve constituting the inspection terminal 12, for example, an oxygen-free copper tube with a thickness of about 0.45 mm and a length of 5 mm may be used. Furthermore, the length L from the end of the protective layer 15 and the outer jacket 16 of the optical cable 10 to the end of the inspection terminal 12 is set to be slightly shorter than the length of the boot 11C of the optical connector 11. By inserting the end of the cable configured as described above into the boot 11C, the optical connector 11 is attached to the end of the optical cable 10. Although not shown, the other end of the optical cable 10 is similarly attached. In this way, an optical cable provided with optical connectors 11 on both ends is obtained, as shown in FIG.

[0026] In the embodiment shown in FIG. 2(A), an optical cable is described that incorporates protective layer 15 made of stainless steel material wound in a spiral shape into a cylindrical shape. However, protective layer 15 is not limited to a spiral shape, and may be a mesh-like material formed into a cylindrical shape, for example. 2(B), instead of using the conductive protective layer 15 as a conductive means between a pair of inspection terminals 12 provided at both ends of the optical cable 10, a conductive wire 18 such as a conductive wire penetrating in the axial direction may be embedded in the outer sheath 16 of the optical fiber cores (13, 14), both ends of which protrude beyond the end faces of the optical fiber, bent back 180 degrees, and crimped with a metal sleeve that serves as the inspection terminal 12. The conductive wire 18 may be made of a twisted wire.

[0027] At a site where an optical cable having the above-described configuration is used, a continuity test to check whether the optical cable is connected correctly is performed by contacting the probes or alligator clips at the ends of the two lead wires extending from the tester with the test terminals 12 at the base of a pair of optical connectors 11 at both ends of the optical cable 10, respectively. Hereinafter, as an example, a specific procedure for checking the cable connection state in an optical distribution box to which an optical cable is connected as a signal transmission cable will be described.

[0028] A schematic configuration of the inside of the optical distribution box is shown in Fig. 4. Note that Fig. 4 shows the state where the double doors provided on the front side of the optical distribution box are open. As shown in Fig. 4, the optical distribution box 20 has a plurality of trays 22 arranged vertically in a multi-layered manner within a vertically long housing 21. Each tray 22 has a plurality of relay connectors built in for connecting a plurality of optical connectors to each other. Then, optical connectors 11 at the ends of optical cables (optical cords) extending from various devices and equipment installed at the station, optical cables extending to multiple stations, and optical cables connecting between trays are connected to a designated relay connector of a designated tray, so that the optical distribution box 20 appropriately distributes the transmission destinations of information. Note that the plurality of relay connectors in the tray 22 are arranged in an array, and the space other than the connector array is used as a space for storing surplus portions of optical cables.

[0029] 4, since many optical cables 10 are collected in the optical distribution box 20, it is difficult to visually distinguish the cords when checking whether the optical cables (optical cords) connecting the trays are correctly connected. Here, if an optical cable having an inspection terminal 12 provided at the base of the connector at the end as described in the above embodiment is used as the optical cable (optical cord), the connection confirmation inspection can be performed using the inspection terminal 12.

[0030] Specifically, when the connector of the optical cable 10 is first connected to the optical distribution box 20, the work is performed while referring to a drawing or list showing the connection relationship of the cable. Therefore, in the connection confirmation inspection, the above drawing or list is also referred to first to identify the two connectors of the optical cable to be inspected. Then, the inspection terminal 12 at the base of one of the two identified connectors is clamped with an alligator clip at the end of one of the two lead wires extending from the tester. Next, the inspection terminal 12 at the base of the other of the two identified connectors is clamped with an alligator clip at the end of the other lead wire extending from the tester.

[0031] At this time, if the cable is connected correctly, current flows between the inspection terminals 12 via the metal protective layer 15 inside the cable, and the tester detects this and generates a sound or turns on a lamp. On the other hand, if a connector of another cable is mistakenly connected to the intermediate connector of interest, no current flows between the inspection terminals 12, so the tester does not generate a sound or turn on a lamp. Therefore, by checking whether the tester generates a sound or turns on a lamp, it is possible to determine whether the connections are correct.

[0032] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments and various modifications and changes are possible. For example, the above embodiments show an optical cable provided with one optical fiber core, but the present invention can also be applied to an optical cable provided with multiple optical fiber cores in one sheath. In addition, in the above embodiment, an optical distribution box having a tray with a built-in relay connector is shown, but instead of the above tray, an optical distribution box having a plurality of connector terminals to which the optical connector 11 at the end of the optical cable 10 is connected and optical transmission paths connecting the terminals, or a plurality of substrates carrying photoelectric conversion elements and signal lines, may be used.

[0033] Furthermore, in the above embodiment, the present invention has been described as being applied to an optical cable, but the present invention can also be applied to a cable that uses a conductor as a core wire to transmit an electric signal and has a protective layer surrounding one or more core wires. Even if there is no protective layer, in a cable that has multiple conductors built in, one of the conductors can be selected and used as a substitute for wires 17A, 17B and protective layer 15 in the above embodiment, and the selected conductor can be folded back and crimped with a metal sleeve to provide an inspection terminal 12, allowing a connection confirmation inspection to be performed.

[0034] Furthermore, the cable connection status checking method of the present invention is not limited to optical distribution boxes to which optical cables are connected, but can be used for connection checking work in distribution boxes to which connection parts (connectors or terminals) at the ends of signal transmission cables (metal cables) that electrically transmit signals are connected. In particular, in wiring boxes to which metal cables are connected, the trays or boards on which the connection parts are mounted may be arranged in a multi-layered configuration, or in a vertical or matrix configuration, and the present invention can also be applied to connection confirmation work in wiring boxes with such a configuration. [Explanation of symbols]

[0035] 10 Optical cable (signal transmission cable) 11 Optical connector (connecting part) 12 Test terminal 13 Optical Fiber 14 Hull 15 Protection layer 16 Sheath 17A, 17B Wire 18 Conductor 20 Optical wiring box 21 Case 22 Tray (substrate)

Claims

1. A signal transmission cable in which one or more signal lines capable of transmitting electric or optical signals are covered with a sheath or outer jacket and connecting parts are provided at both ends, a pair of inspection terminals provided at a base portion of the connection part so as to be exposed on an outer circumferential surface of the sheath or the outer cover, a first terminal for inspection that is electrically connected to a first conductor that is disposed within a sheath or between the signal line and the outer cover and that extends in an axial direction of the cable;

2. 2. The signal transmission cable according to claim 1, wherein the signal line is an optical fiber core for transmitting an optical signal.

3. the linear conductor is a protective layer made of a conductive metal formed so as to surround the one or more signal lines; the inspection terminal is a sleeve made of a conductive and plastically deformable material, A signal transmission cable as described in claim 1 or 2, characterized in that the cable has one or more conductive wires at both ends, each of which is sandwiched between the inner surface of the sleeve and the outer surface of the outer jacket, with one end being in electrical contact with the protective layer and the other end being folded back in the axial direction of the cable and joined to the outer surface of the sheath or the outer jacket.

4. the protective layer is formed by winding a linear conductive metal spirally around the one or more signal lines, 4. The signal transmission cable according to claim 3, wherein one end of the one or more conductive wires is inserted along a spiral groove in the protective layer.

5. 3. A cable connection state checking method for checking connection states of signal transmission cables in a distribution box in which a plurality of trays or boards, each having a plurality of relay connectors or connector terminals mounted thereon, are stored in a housing in a layered, vertical or matrix manner, and connection parts at both ends of a plurality of signal transmission cables according to claim 1 or 2 are connected to the relay connectors or connector terminals, respectively, comprising: A step of identifying two connection parts that are considered to be connection parts at the end of the signal transmission cable to be inspected by referring to a drawing or a list showing the connection relationship of the signal transmission cable; a step of bringing a contactor at an end of one of two lead wires extending from an inspection device into contact with the inspection terminal at a base of one of the two identified connection parts; a step of bringing a contactor of a lead wire at an end of the other of two lead wires extending from the inspection device into contact with the inspection terminal at a base of the other of the two identified connection parts; a step of determining whether or not the signal transmission cable to be inspected is correctly connected based on the presence or absence of sound or light emitted by the inspection device; 13. A method for checking a cable connection state, comprising:

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