Optical cable branching device

Abstract

The present invention has: at least one sub-connector (S) that branches at least one optical fiber (f1-f4) disposed between a first main connector (21) and a second main connector (22); and at least one cap (C) that can be connected to the sub-connector (S). In the sub-connector (S), at least one pair of end parts including a first end part and a second end part obtained by cutting the optical fiber is disposed. The cap (C) is constructed in at least one of connection between the pair of end parts, opening between the pair of end parts, and drawing-out of the pair of end parts.

Description

Optical cable branching device

[0001] The present disclosure relates to an optical cable branching device used to branch an optical cable.

[0002] Optical fibers for communication are subject to connection switching operations in response to changes in communication demand, etc. Non-Patent Documents 1 and 2 disclose that a closure is installed on the route of an optical cable, and when switching connections, such as switching the optical fiber connection from a main route to a branch route, the optical fiber route switching operation is performed within the closure.

[0003] Furthermore, Non-Patent Document 3 describes a technology for a remote optical path switching node operated in an optical access network, and discloses that the output destination of communication light is switched and output by a remote control function.

[0004] Chihiro Suzuki, Yuji Takahashi, Atsushi Hamaoka, and Kazutoshi Takamizawa, "Technology for Reconnecting Optical Fiber Cable in Existing Aerial Closures," NTT Technical, Vol. 10, No. 6, June 2012, pp. 1-7. Yuji Aoyagi, "5-2 Optical Fiber Cable Connection," IEICE Knowledge Base Group 5 (Communications and Broadcasting), Part 2 (Optical Access Line and Transmission Technology), Chapter 5, Optical Connection Technology, pp. 20-22, 2017. Hiroshi Watanabe, Tomohiro Kawano, Chisato Fukai, Ryo Koyama, Kazuhide Nakae, Tatsuya Fujimoto, Yoshiteru Abe, Kazunori Katayama, "Remote Optical Path Switching Node Operating in a Multistage Loop-Type Optical Access Network," 2021 IEICE Society Conference, BK-2-3, 2021.

[0005] However, with the techniques disclosed in Non-Patent Documents 1 and 2, when reconnecting optical fibers, manual switching from a main route to a branch route is required. Many optical fibers are housed in a closure. Furthermore, the outer diameter of the optical fiber is as small as about 0.25 mm. Therefore, when a worker removes a specific optical fiber from the closure and reconnects it, problems such as accidentally cutting an optical fiber other than the one being switched can easily occur.

[0006] Furthermore, to switch optical fibers within a closure, connection methods such as connectors, fusion splicing, and mechanical splicing are used. However, these connection methods require tools such as connector jigs and fusion splicers, and the optical fiber must be temporarily pulled out of the closure. For this reason, it is necessary to provide an excess length of optical fiber within the closure, and space is required within the closure to store the excess length of optical fiber. Furthermore, when the closure is used for a loop circuit, it is necessary to provide an excess length of optical fiber at both connection ports of the closure, which requires additional storage space within the closure, resulting in a problem of an increased size of the closure.

[0007] Furthermore, although the technology disclosed in Non-Patent Document 3 is compatible with star circuits, loop circuits, and mesh circuits, power is required to drive the optical cross-connect unit, which limits the installation locations and the number of installations in the longitudinal direction, and does not take into consideration the branching of optical cables at any position as with conventional closures.

[0008] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide an optical cable branching device that allows optical fibers to be switched at any location with a simple operation.

[0009] An optical cable branching device according to one embodiment of the present disclosure comprises at least one sub-connector that branches at least one optical fiber arranged between a first main connector and a second main connector, and at least one cap that can be connected to the sub-connector, wherein the sub-connector has at least one pair of ends arranged thereon, each pair including a first end and a second end that are cut from the optical fiber, and the cap is applied to at least one of the connection between the pair of ends, the opening between the pair of ends, and the drawing out of the pair of ends.

[0010] According to the present disclosure, it is possible to switch the branch of an optical fiber at any desired location with a simple operation.

[0011] FIG. 1 is an explanatory diagram showing the configuration of an optical cable branching device according to a first embodiment. FIG. 2A is an explanatory diagram showing the configuration of a U-turn cap C-1. FIG. 2B is an explanatory diagram showing the configuration of a U-turn cap C-2. FIG. 2C is an explanatory diagram showing the configuration of a star line branching cap C-3. FIG. 2D is an explanatory diagram showing the configuration of a star line branching cap C-4. FIG. 3A is a perspective view schematically showing optical fiber lines connected in a star line and a loop line. FIG. 3B is a plan view schematically showing optical fiber lines connected in a star line and a loop line. FIG. 4 is an explanatory diagram showing the configuration of a cap C-3a with a mark indicating the connection of optical fibers. FIG. 5 is an explanatory diagram showing the configuration of a cap C-5 that reflects light of a specific frequency band and transmits light of other frequencies. FIG. 6 is an explanatory diagram showing the configuration of a housing mounted in an optical cable branching device according to a second embodiment. FIG. 7A is an explanatory diagram showing the configuration of a cap C-11 that makes a U-turn on both of two end pairs. Figure 7B is an explanatory diagram showing the configuration of cap C-12, which branches both sets of end pairs to loop or star lines. Figure 7C is an explanatory diagram showing the configuration of cap C-13, which makes a U-turn on one of two sets of end pairs and branches the other set to loop or star lines. Figure 8A is an explanatory diagram showing the configuration of cap C-21, which makes a U-turn on all four sets of end pairs. Figure 8B is an explanatory diagram showing the configuration of cap C-22, which branches all four sets of end pairs to loop or star lines. Figure 8C is an explanatory diagram showing the configurations of caps C-23 and C-24, which make a U-turn on three of four sets of end pairs and branch the remaining set to loop or star lines. Figure 8D is an explanatory diagram showing the configurations of caps C-25 and C-26, which make a U-turn on two of four sets of end pairs and branch the remaining two sets to loop or star lines. Fig. 8E is an explanatory diagram showing the configuration of caps C-27 and C-28, which make a U-turn on two of the four pairs of end points and branch the other two pairs into loop or star circuits. Fig. 8F is an explanatory diagram showing the configuration of caps C-29 and C-30, which make a U-turn on one of the four pairs of end points and branch the other three pairs into loop or star circuits.

[0012] [Description of First Embodiment] The following describes the embodiment with reference to the drawings. FIG. 1 is an explanatory diagram showing the configuration of an optical cable branching device according to the first embodiment. As shown in FIG. 1, an optical cable branching device 100 (hereinafter abbreviated as "branching device 100") includes a housing 1 and one or more (four in the figure) caps C-1 to C-4 connected to the housing 1. Note that, although an example in which four caps C-1 to C-4 are installed will be described in this embodiment, the number of caps is not limited to four and may be one to three, or five or more. In the following, when each cap is specifically referred to, it will be referred to with a suffix, such as "cap C-1." When not specifically referred to or when referring to a generic term, it will be referred to without a suffix, such as "cap C."

[0013] The housing 1 has a rectangular parallelepiped shape that is completely closed. The housing 1 has a waterproof structure. Two opposing side surfaces (left and right surfaces in the figure) of the housing 1 are connection surfaces s1 and s2. The side surface (bottom surface in the figure) perpendicular to each of the connection surfaces s1 and s2 is the mounting surface s3. A first main connector 21 is provided on the connection surface s1, and a second main connector 22 is provided on the connection surface s2. Sub-connectors S-1 to S-4, which will be described later, are provided on the mounting surface s3. Hereinafter, the first and second main connectors 21 and 22 will be simply referred to as the "main connector 21" and the "main connector 22." The main connectors 21 and 22 are equipped with n-core (n≧1; 4-core in FIG. 1 ) optical fibers f1 to f4.

[0014] An external connector 31, which is connected to a main cable 32, is connected to the main connector 21. The main connector 21 and the external connector 31 are, for example, MPO connectors that connect multiple optical fibers together. A user can attach and detach the external connector 31 to the main connector 21. An external connector 33 of a main cable 34 is connected to the main connector 22. The main connector 22 and the external connector 33 are, for example, MPO connectors. A user can attach and detach the external connector 33 to the main connector 22. The main cables 32, 34 are equipped with, for example, four optical fibers.

[0015] The optical fiber f1 is split into two optical fibers f1a and f1b inside the housing 1. An end portion (first end portion x1a) of the optical fiber f1a and an end portion (second end portion x1b) of the optical fiber f1b form a pair of ends x1.

[0016] Similarly, optical fibers f2 to f4 are each divided into two optical fibers f2a to f4a and two optical fibers f2b to f4b inside the housing 1. Ends of optical fibers f2a to f4a (first ends x2a to x4a) and ends of optical fibers f2b to f4b (second ends x2b to x4b) form end pairs x2 to x4, respectively. That is, four optical fibers f1 to f4 form four sets of end pairs x1 to x4.

[0017] Each pair of ends x1 to x4 is housed in a sub-connector S-1 to S-4 provided on the mounting surface s3. In the following, when a sub-connector is specifically referred to, it will be referred to with a suffix such as "sub-connector S-1," and when it is not specifically referred to or when it is referred to generically, it will be referred to without a suffix as "sub-connector S." The sub-connector S branches at least one optical fiber arranged between the main connector 21 (first main connector) and the main connector 22 (second main connector).

[0018] Each sub-connector S can be connected to various types of caps C. The sub-connectors S and caps C are, for example, LC connectors that allow for high-density mounting. In the example shown in Figure 1, U-turn caps C-1 and C-2 are connected to the sub-connectors S-1 and S-2, respectively.

[0019] A star line branching cap C-3 is connected to the sub-connector S-3, and a loop line branching cap C-4 is connected to the sub-connector S-4.

[0020] The housing 1 has a watertight structure at the connection portions of the main connectors 21, 22 and the sub-connectors S.

[0021] FIG. 2A is an explanatory diagram showing the configuration of the U-turn cap C-1 shown in FIG. 1. Inside the cap C-1, two optical fibers q1 and q2, which are connected to the two optical fibers f1a and f1b (see FIG. 1) of the end pair x1, and two mirrors 41a and 41b are mounted. Each mirror 41a and 41b is installed at approximately 45 degrees to the longitudinal direction of each optical fiber q1 and q2. Light transmitted to the optical fiber f1a is introduced into the optical fiber q1, reflected by the two mirrors 41a and 41b, and introduced into the optical fiber f1b via the optical fiber q2. In other words, by connecting the cap C-1 to the sub-connector S-1, light transmitted from the optical fiber f1a can be introduced directly into the optical fiber f1b. Conversely, light transmitted from the optical fiber f1b can be introduced directly into the optical fiber f1a.

[0022] That is, the cap C-1 is provided with mirrors 41a and 41b that reflect light output from one of the first end x1a and second end x1b of the end pair x1 and introduce it into the other end.

[0023] 2B is an explanatory diagram showing the configuration of the U-turn cap C-2 shown in FIG. 1. An arc-shaped optical fiber 42 is mounted inside the cap C-2. The two ends of the optical fiber 42 are connected to the optical fibers f2a and f2b (see FIG. 1) of the end pair x2. Light introduced into the optical fiber f2a is introduced into the optical fiber f2b via the optical fiber 42. That is, by connecting the cap C-2 to the sub-connector S-2, light transmitted from the optical fiber f2a can be introduced directly into the optical fiber f2b. Conversely, light transmitted from the optical fiber f2b can be introduced directly into the optical fiber f2a.

[0024] That is, the cap C-2 is provided with a U-turn optical fiber 42 that connects the first end x2a and the second end x2b of the end pair x2.

[0025] 2C is an explanatory diagram showing the configuration of the cap C-3 for branching the star line shown in FIG. 1. One optical fiber 43 is provided within the cap C-3. The optical fiber 43 is connected to the end of one (here, optical fiber f3a) of the two optical fibers f3a and f3b (see FIG. 1) of the end pair x3. The end of the other optical fiber f3b is open. In other words, by connecting the cap C-3 to the sub-connector S-3, the optical fiber f3a can be extracted through the optical fiber 43 and branched into the star line.

[0026] That is, the cap C-3 includes a first optical fiber (optical fiber 43) connected to one of the first end x3a and the second end x3b of the end pair x3.

[0027] 2D is an explanatory diagram showing the configuration of the loop branching cap C-4 shown in FIG. 2. Two optical fibers 44 and 45 are provided inside the cap C-4. The optical fibers 44 and 45 are respectively connected to the ends of the two optical fibers f4a and f4b (see FIG. 1) of the end pair x4. That is, by connecting the cap C-4 to the sub-connector S-4, the optical fibers f4a and f4b can be extracted to the optical fibers 44 and 45 and branched into a loop line.

[0028] That is, the cap C-4 includes two second optical fibers (optical fibers 44, 45) for extracting both the first end x4a and the second end x4b of the end pair x4 to the outside. Note that by disabling one of the two optical fibers 44, 45 provided in the cap C-4, the cap C-4 can also be used as the cap C-3 shown in FIG. 2C.

[0029] Any of the caps C shown in Figures 2A to 2D can be connected to each sub-connector S shown in Figure 1. In other words, by appropriately selecting and attaching a cap C to be connected to each sub-connector S installed in the housing 1, the user can select between connecting the pairs of ends, opening the pairs of ends, and pulling out the pairs of ends.

[0030] For example, when the U-turn cap C-1 shown in FIG. 2A is connected to the sub-connector S-1 as shown in FIG. 1, the light transmitted to the optical fiber f1a can be introduced directly into the optical fiber f1a.

[0031] When the U-turn cap C-2 shown in FIG. 2B is connected to the sub-connector S-2, the light transmitted through the optical fiber f2a can be introduced directly into the optical fiber f2b.

[0032] When the star line branching cap C-3 shown in FIG. 2C is connected to the sub-connector S-3, the light transmitted to the optical fiber f3a can be introduced into the optical fiber 43 and branched to the star line.

[0033] 2D is connected to the sub-connector S-4, the light transmitted through the optical fibers f4a and f4b can be introduced into the optical fibers 44 and 45, respectively, and branched into the loop line. In this way, by selecting the cap C to be connected to each sub-connector S, it becomes possible to switch the connection of each of the optical fibers f1 to f4 without removing the optical fibers f1 to f4 from the housing 1.

[0034] Fig. 3A is an explanatory diagram showing an example of an overhead wiring of optical fiber lines connected in a star line and a loop line, and Fig. 3B is a plan view of the line shown in Fig. 3B. As shown in Fig. 3A and Fig. 3B, an optical cable F1 is arranged in a clockwise or counterclockwise loop shape from a feeder point, i.e., a support post 71, via a plurality of support posts 72, with a feeder point closure B1 installed at the support post 71 and optical cable branching devices b1 to b6 installed at the plurality of support posts 72.

[0035] Specifically, in the clockwise direction, optical cable F1 is connected from feeder closure B1 to branching devices b1, b2, b3, b4, b5, and b6 in this order, forming a main line route using a loop circuit. Optical cable F2 is also connected to branching device b4. Optical cable F2 is connected to branching devices b4, b7, and b8 in this order. A branch line route using a star circuit is formed by branching devices b4, b7, and b8.

[0036] By employing the branching device 100 according to the present embodiment shown in FIG. 1 as each of the branching devices b1 to b8 shown in FIG. 3A and FIG. 3B, for example, optical cables W1 to W8 can be branched from each of the branching devices b1 to b8 with a simple operation. While FIG. 3A and FIG. 3B show examples in which optical cables are connected by loop lines and star lines, mesh lines may also be used. Furthermore, while FIG. 3A and FIG. 3B show examples in which optical cable lines are installed overhead, the lines may also be installed in underground structures.

[0037] Thus, the branching device 100 according to this embodiment has at least one sub-connector S that branches at least one optical fiber f1 to f4 arranged between the main connector 21 (first main connector) and the main connector 22 (second main connector), and at least one cap C that can be coupled to the sub-connector S. The sub-connector S has at least one set of end pair x1 to x4, each of which includes a first end and a second end obtained by cutting the optical fibers f1 to f4, arranged therein, and the cap C is applied to at least one of the connection between the end pair, the opening between the end pair, and the drawing out of the end pair.

[0038] In this embodiment, the branching of the optical cable can be changed by the simple operation of changing the type of cap C connected to each sub-connector S of the housing 1. That is, the end pairs x1 to x4 can be switched between connection, release, and branching. This eliminates the need for delicate work, such as removing a desired optical fiber from multiple optical fibers inserted in a closure and switching the connection, as in the past. Furthermore, regardless of the connection method, such as a star circuit or a loop circuit, it is possible to change the branching of the optical cable with a simple operation. This significantly reduces the effort required for branching the optical cable.

[0039] Furthermore, each sub-connector S has a watertight structure, so that water and foreign matter can be prevented from entering the inside of the housing 1.

[0040] In this embodiment, when changing the connection of the optical cable, there is no need to remove the optical fiber from inside the housing 1, so there is no need to provide excess length of optical fiber inside the housing 1. Also, there is no need to use a tray for storing the optical fiber when changing the connection, which makes it possible to make the housing 1 more compact.

[0041] Furthermore, when connecting various types of caps C to the branching device 100, it is necessary to confirm whether the branching device 100 is connected to a loop line or a star line. That is, when the branching device 100 is connected to a loop line, light is transmitted from both of the two main connectors 21 and 22 shown in FIG. 1. When the branching device 100 is connected to a star line, light is transmitted from one of the two main connectors 21 and 22. For this reason, it is necessary to confirm whether the branching device 100 is connected to a loop line or a star line. A method for confirming whether the branching device 100 is connected to a loop line or a star line will be described below.

[0042] As described above, in a loop line, light reaches the branching device 100 from both of the two main connectors 21, 22. Therefore, if a light receiving device is inserted into a sub-connector S that does not have a cap C connected, among the four sub-connectors S-1 to S-4 shown in Fig. 1, and light reaches the sub-connector S from both of the two optical fibers (e.g., f4a, f4b) that make up an end pair (e.g., x4), it can be determined that the branching device 100 is connected to a loop line.

[0043] On the other hand, in a star line, light reaches the branching device 100 from one of the two main connectors 21, 22. Therefore, if a light receiving device is inserted into a sub-connector S that does not have a cap C connected, among the four sub-connectors S-1 to S-4 shown in Figure 1, and light reaches the branching device 100 from one of the two optical fibers that make up the end pair, it can be determined that the branching device 100 is connected to a star line. In addition, the optical fiber side where the light reaches can be recognized as the upstream side for transmitting light.

[0044] Therefore, by checking in advance whether the line is a loop line or a star line using the above method, it becomes possible to select an appropriate cap C to be connected to each sub-connector S.

[0045] In this embodiment, pairs of ends can be connected by connecting each U-turn cap C-1 or C-2 to the sub-connector S. By connecting a star line branching cap C-3 to the sub-connector S, one end of the pair of ends can be pulled out and the other end can be opened, allowing it to branch into a star line. By connecting a loop line branching cap C-4 to the sub-connector S, both ends of the pair of ends can be pulled out and branched into a loop line.

[0046] Fig. 4 is an explanatory diagram showing a modification of the star line branching cap C-3 shown in Fig. 2C. As shown in Fig. 4, the modified cap C-3a has a mark 46 on the peripheral surface indicating the connection of the optical fiber 47. That is, the cap C-3a has a mark 46 indicating the first optical fiber (optical fiber 47).

[0047] The mark 46 allows the user to reliably connect the optical fiber 47 to the desired optical fiber of the end pair, and prevents installation errors when connecting the cap C-3a to the sub-connector S. In addition, by appropriately setting the shape and color of the mark 46, it is possible to make it easier for the user to distinguish between them.

[0048] FIG. 5 is an explanatory diagram showing another example of the configuration of the cap C. The cap C-5 shown in FIG. 5 includes two optical fibers 48 and 49. The optical fibers 48 and 49 are each connected to two optical fibers (e.g., optical fibers f1a and f1b) of an end pair (e.g., end pair x1 shown in FIG. 1). Wavelength-selective filters 51a and 51b are installed along the path of each optical fiber 48 and 49. The filters 51a and 51b have the function of reflecting light of a specific frequency band and passing light of other frequency bands. That is, the cap C-5 includes filters 51a and 51b that pass only wavelengths of a specific band among the light transmitted from the first end (x1a to x4a) and the second end (x1b to x4b).

[0049] By connecting the cap C-5 to the sub-connector S, light of a specific frequency band can be reflected and made to make a U-turn. Furthermore, light of frequencies other than the specific band can be transmitted, allowing it to be branched into a star line or a loop line.

[0050] [Description of Second Embodiment] Next, a second embodiment will be described. Fig. 6 is an explanatory diagram showing the configuration of a housing 1A mounted in an optical cable branching device according to the second embodiment. As shown in Fig. 6, the housing 1A, like the housing 1 of the branching device 100 shown in Fig. 1, includes a first main connector 21A, a second main connector 22A, and four sub-connectors S-11 to S-12.

[0051] The second embodiment also differs from the first embodiment in that eight optical fibers f11 to f18 are provided between the main connector 21A and the main connector 22A, and four optical fibers are introduced into each of the sub-connectors S-11 to S-14. Eight optical fibers are mounted on main cables 52 and 54 connected to external connectors 51 and 53 connected to the main connectors 21A and 22A, respectively. Other configurations are the same as those shown in FIG. 1, and therefore a description of the configuration will be omitted.

[0052] The two optical fibers f11 and f12 are split into two inside the housing 1A to form two pairs of end portions x11 and y11. The two pairs of end portions x11 and y11 (i.e., four optical fibers) are housed in the sub-connector S-11.

[0053] Similarly, the other optical fibers f13 to f18 are split into two inside the housing 1A. Two pairs of end portions x12, y12 of two optical fibers f13, f14 are housed in the sub-connector S-12. Two pairs of end portions x13, y13 of two optical fibers f15, f16 are housed in the sub-connector S-13. Two pairs of end portions x14, y14 of two optical fibers f17, f18 are housed in the sub-connector S-14. That is, each sub-connector S houses two pairs of end portions.

[0054] Each sub-connector S shown in Fig. 6 can be connected to various caps C. Figs. 7A to 7C are explanatory diagrams showing examples of caps C that can be connected to each sub-connector S shown in Fig. 6.

[0055] Figure 7A is an explanatory diagram showing a cap C-11 that makes a U-turn connection for each end pair x11, y11 introduced into a sub-connector S-11. As shown in Figure 7A, the cap C-11 has two optical fibers 61, 62 that connect to each end pair x11, y11 (see Figure 6). The optical fiber 61 makes a U-turn connection for the two optical fibers of the end pair x11, and the optical fiber 62 makes a U-turn connection for the two optical fibers of the end pair y11. Therefore, when the cap C-11 is connected to the sub-connector S-11 shown in Figure 6, for example, the split optical fibers f11, f12 can be connected. In other words, the two main connectors 21A, 22A shown in Figure 6 can be directly connected using the optical fibers f11, f12.

[0056] 7B is an explanatory diagram showing a cap C-12 that branches off each pair of end portions x12, y12 introduced into the sub-connector S-12. As shown in FIG. 7B, the cap C-12 has a configuration that branches off the four optical fibers of each pair of end portions x12, y12 (see FIG. 6) to external optical fibers 63 to 66. Therefore, when the cap C-12 is connected to the sub-connector S-12 shown in FIG. 6, for example, the split optical fibers f13 and f14 can be branched off to the external optical fibers 63 to 66.

[0057] 7C is an explanatory diagram showing a cap C-13 that makes a U-turn connection of one pair of ends x13 introduced into a sub-connector S-13 and a branch connection of the other pair of ends y13. As shown in Fig. 7C, the cap C-13 connects one pair of ends x13 to an optical fiber 67 and connects the other pair of ends y13 to two optical fibers 68 and 69. Therefore, by connecting the cap C-13 to the sub-connector S-13 shown in Fig. 6, it is possible to make a U-turn connection of the optical fiber f15 and a branch connection of the optical fiber f16.

[0058] Furthermore, when branching the optical fiber f15 and making a U-turn connection for the optical fiber f16, the cap C-13 can be inserted in the opposite direction into the sub-connector S-13. That is, the optical fiber 67 can be connected to the end pair y13, and the optical fibers 68 and 69 can be connected to the end pair x13. For example, an LC connector or an MPO connector can be used that allows insertion even when the orientation of the cap C-13 is changed by 180 degrees. That is, the orientation of the cap C-13 when connected to the sub-connector S-13 can be changed.

[0059] As described above, in the optical cable branching device according to the second embodiment, as in the first embodiment described above, it is possible to change the branching of the optical cable by simply changing the type and orientation of the cap C connected to each sub-connector S of the housing 1A. This eliminates the need for delicate work such as removing a desired optical fiber from multiple optical fibers inserted in a closure and switching the connection, as was necessary in the past. This makes it possible to significantly reduce the effort required for branching the optical cable.

[0060] Furthermore, by connecting the cap C-11 shown in Figure 7A to the sub-connector S, it becomes possible to make a U-turn connection between the two optical fibers of the end pair. By connecting the cap C-12 shown in Figure 7B to the sub-connector S, it becomes possible to pull out each optical fiber of the end pair and branch it into a star line or a loop line. By connecting the cap C-13 shown in Figure 7C to the sub-connector S, it becomes possible to make a U-turn connection with one end pair and branch the other end pair into a star line or a loop line.

[0061] [Description of Third Embodiment] Next, a third embodiment will be described. In the optical cable branching device according to the third embodiment, four end pairs (i.e., eight optical fibers) are housed in the sub-connector S shown in Figures 1 and 6. Hereinafter, the four end pairs will be referred to as end pairs x21, y21, z21, and w21, respectively. Figures 8A to 8F are explanatory diagrams showing the configuration of a cap C that can be coupled to a sub-connector S having four end pairs x21, y21, z21, and w21.

[0062] 8A is an explanatory diagram showing the configuration of a cap C-21 that connects all four pairs of end portions x21, y21, z21, and w21 in a U-turn. As shown in FIG. 8A, the cap C-21 is equipped with optical fibers h1 to h4 that connect each pair of end portions x21, y21, z21, and w21 in a U-turn. Therefore, it is possible to connect each pair of end portions x21, y21, z21, and w21 in a U-turn.

[0063] 8B is an explanatory diagram showing the configuration of a cap C-22 that branches off all four pairs of end points x21, y21, z21, and w21. As shown in FIG. 8B, the cap C-22 has eight optical fibers h5 to h12 that are connected to the optical fibers of each pair of end points x21, y21, z21, and w21. Therefore, the optical fibers of each pair of end points x21, y21, z21, and w21 can be branched off into a star line or a loop line.

[0064] 8C is an explanatory diagram showing the configuration of caps C-23 and C-24, which branch-connect one of four pairs of end points x21, y21, z21, and w21 and make a U-turn connection for the other three pairs of end points. As shown in FIG. 8C(a), cap C-23 branches end point pair x21 into two optical fibers h13 and h14, and makes a U-turn connection for end point pairs y21, z21, and w21 using optical fibers h15 to h17. As shown in FIG. 8C(b), cap C-24 branches end point pair y21 into two optical fibers h19 and h20, and makes a U-turn connection for end point pair x21, z21, and w21 using optical fibers h18, h21, and h22. Furthermore, to branch-connect end point pair z21, the cap C-24 shown in FIG. 8C(b) can be simply inverted. When the pair of ends w21 is to be branched and connected, the cap C-23 shown in FIG. 8C(a) is simply inverted.

[0065] 8D and 8E are explanatory diagrams showing the configurations of caps C-25, C-26, C-27, and C-28, which branch and connect two of the four pairs of end portions x21, y21, z21, and w21, and make a U-turn connection for the other two pairs of end portions. As shown in Fig. 8D(a), cap C-25 branches end portion x21 and y21 into two optical fibers h23 to h26, and makes a U-turn connection for end portion z21 and w21 using optical fibers h27 and h28. As shown in Fig. 8D(b), cap C-26 branches end portion x21 and z21 into two optical fibers h29, h30, h32, and h33, and makes a U-turn connection for end portion y21 and w21 using optical fibers h31 and h34. As shown in Fig. 8E(c), cap C-27 branches each of the pair of ends y21 and z21 into two optical fibers h36 to h39, and connects the pair of ends x21 and w21 in a U-turn using optical fibers h35 and h40. As shown in Fig. 8E(d), cap C-28 branches each of the pair of ends x21 and w21 into two optical fibers h41, h42, h45, and h46, and connects the pair of ends y21 and z21 in a U-turn using optical fibers h43 and h44.

[0066] Furthermore, when the pair of ends z21 and w21 is branched and the pair of ends x21 and y21 is U-turn connected, the cap C-25 shown in Fig. 8D(a) can be inverted. When the pair of ends y21 and w21 is branched and the pair of ends x21 and z21 is U-turn connected, the cap C-26 shown in Fig. 8D(b) can be inverted.

[0067] 8F is an explanatory diagram showing the configuration of caps C-29 and C-30, which connect one of four pairs of end portions x21, y21, z21, and w21 in a U-turn and branch the other three pairs of end portions. As shown in FIG. 8F(a), cap C-29 connects end portion x21 in a U-turn using optical fiber h47, and branches end portion y21, z21, and w21 into two optical fibers h48 to h53, respectively. As shown in FIG. 8F(b), cap C-30 connects end portion y21 in a U-turn using optical fiber h56, and branches end portion x21, z21, and w21 into two optical fibers h54, h55, and h57 to h60, respectively. Furthermore, to connect end portion z21 in a U-turn, cap C-30 shown in FIG. 8F(b) can be simply inverted. When the end pair w21 is to be connected in a U-turn, the cap C-29 shown in FIG. 8F(a) is simply inverted.

[0068] In this way, in the optical cable branching device of the third embodiment, by using each of the caps shown in Figures 8A to 8F, it is possible to switch connections corresponding to a sub-connector S having eight optical fibers.

[0069] In the third embodiment, as in the first and second embodiments, the branching of the optical cable can be changed by the simple operation of changing the cap C connected to each sub-connector S of the housing. This eliminates the need for delicate work such as removing the desired optical fiber from the multiple optical fibers inserted in the closure and switching the connection, as in the conventional case. This makes it possible to significantly reduce the effort required for branching the optical cable.

[0070] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure.

[0071] REFERENCE SIGNS 1, 1A Housing 21, 21A Main connector (first main connector) 22, 22A Main connector (second main connector) 31, 33, 51, 53 External connector 32, 34, 52, 54 Main cable 41a, 41b Mirror 42 Optical fiber (U-turn optical fiber) 43 Optical fiber (first optical fiber) 44, 45 Optical fiber (second optical fiber) 46 Mark 51a, 51b Filter 100 Optical cable branching device f1 to f4, f11 to f18 Optical fibers x1a, x2a, x3a, x4a First end x1b, x2b, x3b, x4b Second end x1 to x4, x11 to x14, y11 to y14 End pair x21 to x24, y21 to y24, z21 to z24, w21 to w24 End pair C Cap S Sub-connector

Claims

1. An optical cable branching device having at least one sub - connector for branching at least one optical fiber disposed between a first main connector and a second main connector, and at least one cap connectable to the sub - connector, wherein at least one pair of ends including a first end and a second end of the cut optical fiber is disposed in the sub - connector, and the cap is configured for at least one of connection between the pairs of ends, opening between the pairs of ends, and pulling out of the pairs of ends.

2. The optical cable branching device according to claim 1, wherein the optical fiber is disposed in a housing and the sub - connector is mounted on the housing.

3. The optical cable branching device according to claim 1 or 2, wherein the cap includes a mirror for reflecting light output from one of the first end and the second end of the pair of ends and introducing it to the other end.

4. The optical cable branching device according to claim 1 or 2, wherein the cap includes an optical fiber for U - turn connecting the first end and the second end of the pair of ends.

5. The optical cable branching device according to claim 1 or 2, wherein the cap includes a first optical fiber connected to one of the first end and the second end of the pair of ends.

6. The optical cable branching device according to claim 5, wherein a mark indicating the first optical fiber is attached to the cap.

7. The optical cable branching device according to claim 1 or 2, wherein the cap includes two second optical fibers for pulling out both the first end and the second end of the pair of ends to the outside.

8. The optical cable branching device according to claim 7, wherein the cap includes a filter for passing only wavelengths in a predetermined band among the light transmitted from the first end and the second end.

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