splice tray

Abstract

The present application aims to provide a splice holder having a structure that has a drainage function for preventing water from being in contact with an optical fiber core wire for a temporary water immersion and improving the operability of opening and closing. The splice holder protects a connection portion connecting optical fiber core wires housed in optical cables to each other, and is characterized by including a core wire housing portion that divides an inside of the splice holder into a first space and a second space, the first space being a road surface side, having a main cable insertion hole through which the optical cable is introduced from the outside, the second space being a side opposite to the road surface, provided with the connection portion, the core wire housing portion being a frustoconical shape with two open bottom surfaces and a smaller-area bottom surface of the two bottom surfaces protruding toward the road surface side, the smaller-area bottom surface of the two bottom surfaces being a cable insertion hole through which the optical cable is introduced from the first space to the second space, and not in contact with a bottom surface of the road surface side of the first space.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical cable joint box that protects a connection portion of an optical fiber housed in an optical cable. BACKGROUND

[0002] At present, in order to introduce a network using an optical cable to a user's house, an optical cable is laid underground and in the air. In the case where the optical cable is laid over a long distance and needs to be extended, or when wiring is performed to lead out a core wire required by a user, an optical fiber core wire housed in the optical cable is taken out in a joint box like that of Patent Literature 1, and connection of the core wires to each other is performed. The joint box is provided underground at a position such as a communication tunnel, a manhole, a handhole, which ensures a certain space, and on the other hand, is provided in the vicinity of a telegraph pole on which a cable is erected in the air, and in both cases, it is provided using a large space. If an optical fiber core wire comes into contact with water, its strength decreases, and sometimes, it can have an influence on communication, and therefore, appropriate waterproof measures are performed depending on the setting environment.

[0003] In recent years, in order to cope with the increasing demand for optical fiber communication, in addition to laying an optical cable underground or in the air as described above, sometimes, an optical cable is laid on a road surface as shown in Non-Patent Literature 1.

[0004] PRIOR ART DOCUMENTS

[0005] Patent Literature 1: Japanese Patent Publication No. Hei 1-152917

[0006] Non-Patent Literature 1: Strain Sensing of an In-Road FTTH Field Trial and Implications for Network Reliability, Proc. of IWCS (2018)

[0007] The joint box shown in Patent Literature 1 is provided underground, and in the case where water is not expected to be immersed, in the case where immersion occurs once due to deterioration, water remains and thus the optical fiber core wire comes into contact with water for a long time. In addition, a long time is required for opening and closing operations. On the other hand, the joint box provided in the air is easy to open and close, but does not take into account the case where water is immersed.

[0008] In the case where an optical cable is laid on a road surface, the joint box used on the road surface is sometimes immersed in rain, and there is a first problem that water must not come into contact with the optical fiber core wire for a long time in the joint box. In addition, there is a second problem that, since it is laid on a road surface, opening and closing must be performed in a very short time in order not to interfere with traffic at the time of work. SUMMARY

[0009] Therefore, in order to solve the above problems, the first object of the present application is to provide a joint case having a structure of a water drainage function which prevents water from being in contact with an optical fiber core wire for a long time even if the joint case is temporarily immersed in water. In addition, the second object is to provide a joint case which improves the operability of opening and closing.

[0010] In order to achieve the above objects, the joint case of the present application is provided with a funnel-shaped partition in the inside, and a connection portion of an optical fiber core wire is arranged in the upper layer, thereby making it possible to easily drain water even if water intrudes.

[0011] Specifically, the joint case of the present application protects a connection portion in which optical fiber core wires housed in optical cables are connected to each other, and is characterized in that,

[0012] a core wire housing portion which divides the inside of the joint case into a first space and a second space, the first space being a road surface side and having a main cable insertion hole through which the optical cables are introduced from the outside, and the second space being a side opposite to the road surface and being provided with the connection portion,

[0013] the core wire housing portion being a frustoconical shape in which two bottom surfaces are open and a smaller one of the two bottom surfaces protrudes toward the road surface side,

[0014] the smaller one of the two bottom surfaces being a cable insertion hole through which the optical cables are introduced from the first space to the second space and not being in contact with a bottom surface of the road surface side of the first space.

[0015] The inside of the joint case is divided into two layers by the core wire housing portion. The first space is a space in which the optical cables are introduced from the outside and is a space in which water is allowed to intrude. That is, water is allowed to intrude, and thus water is easily drained, and water which has intruded into the first space is drained in a short time after the water has receded. On the other hand, the second space is a space in which the optical cables from the first space are introduced and the connection portion of the optical fiber core wires is arranged. The core wire housing portion is a frustoconical shape, and thus water which has intruded into the second space is easily drained from the cable insertion hole to the first space after the water has receded.

[0016] In addition, in the case where the second space does not have an air discharge passage, even if the joint case is immersed in water, air is not discharged from the second space, and thus water is difficult to intrude into the second space from the cable insertion hole of the core wire housing portion.

[0017] Therefore, the present application can provide a joint case having a structure of a water drainage function which prevents water from being in contact with an optical fiber core wire for a long time even if the joint case is temporarily immersed in water.

[0018] It is preferable that the inside of the joint box is a space surrounded by a cylindrical main body portion whose upper surface is open and a cylindrical lid portion that seals the upper surface of the main body portion,

[0019] The core wire housing portion is a frustoconical shape,

[0020] The main body portion and the lid portion have screw threads that are threadably connected to each other.

[0021] The lid portion is provided separately from the main body portion. The main body portion is cylindrical, and the lid portion also has a cylindrical shape. Screw threads are provided on the main body portion and the lid portion, and the main body portion and the lid portion can be threadably connected. Thus, the joint box can be opened and closed in a short time even during road work. Therefore, the joint box of the present application can provide improved workability of opening and closing.

[0022] At this time, it is preferable that at least one of the main body portion and the lid portion has a seal member that comes into close contact with the other when threadably connected. By providing a seal member having flexibility between the main body portion and the lid portion, the main body portion and the lid portion can be brought into close contact and sealed.

[0023] In addition, each of the above inventions can be combined as much as possible.

[0024] The present application can provide a joint box having a structure with a water drainage function that prevents water from being in contact with an optical fiber core wire for a long time and prevents water from being in contact with the optical fiber core wire even when temporarily immersed in water. In addition, the present application can provide a joint box with improved workability of opening and closing. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a longitudinal sectional view of the joint box of the present application.

[0026] Figure 2 is a transverse sectional view of the joint box of the present application.

[0027] Figure 3 is a longitudinal sectional view of the joint box of the present application, and is a view showing a manner in which the joint box is provided on a road surface.

[0028] Figure 4 is a view showing a structure of a core wire housing portion in which a cable is inserted and a core wire is housed.

[0029] Figure 5 is a longitudinal sectional view of a lid portion that is threadably connected to a main body portion.

[0030] Figure 6 is a perspective view of a lid portion that is threadably connected to a main body portion.

[0031] Figure 7 is a perspective view of the joint box of the present application. DETAILED DESCRIPTION

[0032] Embodiments of the present application will be described with reference to the accompanying drawings. The embodiments described below are examples of the present application, and the present application is not limited to the following embodiments. In addition, in the specification and drawings, the same components are denoted by the same reference numerals, and the same components have the same functions.

[0033] Figures 1 to 7 is a drawing illustrating a joint box of the present embodiment. Figure 1 is a longitudinal sectional view (a sectional view on a plane perpendicular to a road surface) of the present joint box. Figure 2 is a transverse sectional view (a sectional view on a plane parallel to a road surface) of the present joint box. Figure 3 is a longitudinal sectional view of the present joint box in a state where the joint box is provided to the road surface 50.

[0034] The present joint box is a joint box that protects a connection portion 42 in which optical fiber cores 41 of optical cables 4 housed in the joint box are connected to each other, and the joint box is characterized in that,

[0035] includes a core wire housing portion 2 that divides an inside of the joint box into a first space 15 and a second space 35, the first space 15 is a road surface 50 side, has a main cable insertion hole 11 that introduces the optical cable 4 from the outside, the second space 35 is a side opposite to the road surface 50, and is provided with the connection portion 42,

[0036] The core wire housing portion 2 is a frustoconical shape in which two bottom surfaces (25, 26) are open and a smaller-area bottom surface 26 of the two bottom surfaces (25, 26) protrudes toward the road surface 50 side,

[0037] The smaller-area bottom surface 26 of the two bottom surfaces (25, 26) is a cable insertion hole 21 that introduces the optical cable 4 from the first space 15 to the second space 35, and does not contact a bottom surface 13 of the road surface 50 side of the first space 15.

[0038] In addition, (B) of the present application describes a relationship of the two bottom surfaces (25, 26) of the core wire housing portion 2. Figure 4

[0039] For example, an inside of the present joint box is a space surrounded by a cylindrical main portion 1 whose upper surface is open and a cylindrical cover portion 3 that closes the upper surface of the main portion 1. In addition, the core wire housing portion 2 is a frustoconical shape.

[0040] The core wire housing portion 2 is provided in the inside of the main portion 1 in such a manner that the smaller-area bottom surface of the two bottom surfaces, that is, the cable insertion hole 21 is closer to a bottom surface 13 of the main portion 1 than the other bottom surface, and the cable insertion hole 21 does not contact the bottom surface 13 of the main portion 1.

[0041] ​The main body cable insertion hole 11 is formed in the side surface of the main body 1 at a position closer to the bottom surface 13 of the main body 1 than the position of the cable insertion hole 21 of the core wire housing portion 2.

[0042] The cable fixing member 23 fixes the optical cable 4 introduced from the outside through the main body cable insertion hole 11 and the cable insertion hole 21 on the side of the cover portion 3 of the core wire housing portion 2.

[0043] Figure 4 is a diagram illustrating the core wire housing portion 2. Figure 4 (A) of is a perspective view, Figure 4 (B) of is a side view. The core wire housing portion 2 is configured with the smaller one of the two bottom surfaces (25, 26) on the side of the road surface 50 as the cable insertion hole 21. The core wire housing portion 2 is characterized in that it has a connection point fixing portion 22 that fixes the connection portion 42 on the side of the cover portion 3.

[0044] As shown in Figures 1 to 3 , the present joint box has a cylindrical main body 1.

[0045] The present joint box has a core wire housing portion 2 in the shape of a cone. It is characterized in that the front end of the core wire housing portion 2 is set to face the direction of the road surface 50, and the cable insertion hole 21 is provided in the front end of the core wire housing portion 2, so that even in the case where water enters the core wire housing portion 2, it is easily drained from the cable insertion hole 21. Further, the core wire housing portion 2 is set to have a gap with the bottom surface 13 of the main body 1, so that the drainability is improved. The core wire housing portion 2 can be a cone as shown in Figure 2 , and does not necessarily have to be a conical shape as shown in

[0046] Figure 5 and Figure 6 are diagrams illustrating the cover portion 3. Figure 5 is a longitudinal sectional view of the cover portion 3, Figure 6 is a perspective view of the cover portion 3. The cover portion 3 has a cylindrical shape like the main body 1, and has a hollow structure inside. A threaded portion 31 is provided inside the cover portion 3, and is screwed with the threaded portion provided in the cover setting portion 12 of the main body 1. An operator can open and close the present joint box in a short time by rotating the cover portion 3 without using a special tool.

[0047] At least one of the main body 1 and the cover portion 3 is characterized in that it has a seal 32 that makes the other adhere to it when they are screwed with each other. As shown in Figure 5 and Figure 6As shown, a sealing member 32 is provided inside the cover portion 3. The sealing member 32 is annular and fits tightly against the upper opening of the main body portion 1 when the cover portion 3 is threadedly connected to the main body portion 1. The sealing member 32 prevents water from entering the core wire receiving portion 2 from the cover portion 3. Furthermore, the sealing member 32 defines the channel for air to be discharged from the second space 35 as the cable insertion hole 21 of the receiving portion, which faces the road surface 50. Therefore, even if water temporarily submerges the junction box, it prevents water from seeping into the core wire receiving portion 2 and the second space 35. In this embodiment, an example of the sealing member 32 being provided in the cover portion 3 has been described, but the sealing member can be provided in the main body portion 1, or in both the main body portion 1 and the cover portion 3.

[0048] This junction box structurally achieves both water resistance and drainage for the core wire housing 2. Therefore, when installed on the road surface 50, it can prevent water from remaining in the core wire housing 2 for extended periods, reducing the contact time between water and the optical fiber core wire 41. Even if the cover 3 is not tightly attached to the main body 1 and the water resistance is compromised, the drainage function can still reduce the contact time between water and the optical fiber core wire 41.

[0049] Figure 7 This is a perspective view illustrating the junction box. The optical cable 4, laid on the road surface 50, is inserted and secured through the main cable insertion hole 11, thereby enabling connection to other optical cables 4. Alternatively, multiple main cable insertion holes 11 may be provided, through which multiple optical cables 4 can be inserted. The main cable insertion holes 11 may not necessarily be arranged opposite each other, and the optical cables may not necessarily be inserted into the core wire receiving section 2 opposite each other.

[0050] To further improve the water resistance, the cable can be sealed after it is inserted into the main cable insertion hole 11. However, even if the seal is loosened due to deterioration, the water resistance of the structure of the present invention will not be compromised.

[0051] like Figure 2 As shown, the inserted optical cable 4 is introduced into the second space 35 through the cable insertion hole 21 of the core cable receiving part 2, and is fixed to the core cable receiving part 2 by the cable fixing member 23. Furthermore, the optical fiber core 41 is removed from the optical cable 4. A connection point fixing part 22 is provided in the core cable receiving part 2. Optical fiber connection points 42, which can be used to connect the optical fiber cores 41 of different optical cables 4 to each other, are fixed to the connection point fixing part 22. The connection point 42 can be any of a connector shape or a fusion splice sleeve.

[0052] The above embodiments are not limited to the present invention, and can be modified or improved without departing from the spirit of the present invention, and include equivalents thereof.

[0053] [Postscript]

[0054] It is known that an optical fiber loses its strength due to contact with water for a long time. The joint box of the present invention is capable of accommodating an optical cable laid on a road surface, and a core wire accommodating portion has a cable insertion hole at its bottom, and is provided with a gap from the bottom surface of the main body portion, has a tapered shape, and is provided with its front end directed toward the ground, and the cable insertion hole is provided at its front end, whereby in the case where water enters the core wire accommodating portion, water can be drained from the cable insertion hole.

[0055] The cover portion has a cylindrical shape, is capable of being threadedly connected by a screw thread, and is capable of being opened and closed in a short time, and thus is particularly capable of shortening the work time of work on a road which is required to be performed in a short time for the purpose of not hindering traffic and ensuring work safety.

[0056] Further, the cover portion is capable of being closely attached to the main body portion by having a closure member inside, and a passage for discharging air from a space toward the upper portion of the core wire accommodating portion is defined as the cable insertion hole. Since the cable insertion hole is directed toward the ground, even in the case where the joint box of the present invention is temporarily immersed in water, water can be inhibited from entering the core wire accommodating portion and its upper portion, and thus the contact time of water with the optical fiber can be reduced.

[0057] BRIEF DESCRIPTION OF DRAWINGS

[0058] 1 main body portion

[0059] 11 main body cable insertion hole

[0060] 12 cover setting portion

[0061] 13 main body bottom surface portion

[0062] 15 first space

[0063] 2 core wire accommodating portion

[0064] 21 accommodating portion cable insertion hole

[0065] 22 connection point fixing portion

[0066] 23 cable fixing portion

[0067] 25 bottom surface

[0068] 26 bottom surface

[0069] 3 cover portion

[0070] 31 screw thread portion

[0071] 32 closure member

[0072] 35 second space

[0073] 4 optical cable

[0074] 41 optical fiber core

[0075] 42 optical fiber connection point

[0076] 50 road surface

Claims

1. A joint box that protects a connection portion in which optical fiber cores housed in optical cables are connected to each other, the joint box characterized by, including a core cable housing portion that divides an inside of the joint box into a first space and a second space, the first space being on a road surface side, having a main cable insertion hole through which the optical cables are introduced from the outside, the second space being on a side opposite to the road surface, the connection portion being disposed, the core cable housing portion being a frustoconical shape in which two bottom surfaces are open and a smaller one of the two bottom surfaces protrudes toward the road surface side, the smaller one of the two bottom surfaces being a cable insertion hole through which the optical cables are introduced from the first space to the second space, not being in contact with a bottom surface on the road surface side of the first space.

2. The joint box according to claim 1, characterized by, an inside of the joint box being a space surrounded by a main body portion that is a cylindrical shape with an upper surface open and a cover portion that is a cylindrical shape that closes the upper surface of the main body portion, the core cable housing portion being a circular conical shape, the main body portion and the cover portion having screw threads that are threadedly connected to each other.

3. The splice case of claim 2, wherein, at least one of the main body portion and the cover portion having a seal that brings the main body portion and the cover portion close to each other when threadedly connected to each other.

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