Optical connector and method for attaching optical connector

Abstract

This optical connector is attached to an optical fiber cable. The optical connector is provided with: a stub that holds a short optical fiber; a biasing member that biases the stub; a housing that accommodates a fusion splicing part in which the short optical fiber and an optical fiber exposed from the optical fiber cable are fusion spliced; and a cover that accommodates the stub, the biasing member, and the housing. The housing has a first housing part that has a first through-hole and supports the biasing member, and a second housing part that has a second through-hole and is fixed to the cover. The inner diameter of the first through hole of the first housing part is smaller than the outer diameter of the optical fiber cable and larger than the outer diameter of the optical fiber of the optical fiber cable. The inner diameter of the second through hole of the second housing part is larger than the outer diameter of the optical fiber cable.

Description

Optical connector and optical connector installation method

[0001] This application claims priority to Japanese Patent Application No. 2024-55490, filed March 29, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] Patent Documents 1, 2 and 3 disclose optical connectors that can be attached to optical fiber cables on-site.

[0003] Patent Document 4 discloses an optical connector equipped with a flexible tube.

[0004] Japanese Patent Application Publication No. 2009-205100 Japanese Patent Application Publication No. 2002-082257 U.S. Patent Application Publication No. 2022 / 0326452 U.S. Patent Application Publication No. 2013 / 0209041

[0005] The optical connector of the present disclosure is an optical connector to be attached to an optical fiber cable, and comprises: a stub that holds a short optical fiber; a biasing member that biases the stub; a housing that accommodates a fusion spliced ​​portion where the short optical fiber and an optical fiber exposed from the optical fiber cable are fusion spliced; and a cover that accommodates the stub, the biasing member, and the housing, wherein the housing has a first housing portion having a first through hole and supporting the biasing member, and a second housing portion having a second through hole and fixed to the cover, wherein the inner diameter of the first through hole of the first housing portion is smaller than the outer diameter of the optical fiber cable and larger than the outer diameter of the optical fiber of the optical fiber cable, and the inner diameter of the second through hole of the second housing portion is larger than the outer diameter of the optical fiber cable.

[0006] FIG. 1 is a perspective view illustrating a configuration of an optical connector according to an embodiment of the present disclosure. FIG. 2 is an exploded perspective view of the optical connector. FIG. 3 is a cross-sectional view illustrating a configuration of a cross section taken along line III-III in FIG. 1 as viewed from the direction of the arrow. FIG. 4 is an upper perspective view of a first housing portion. FIG. 5 is a lower perspective view of a second housing portion. FIG. 6 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 7 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 8 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 9 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 10 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 11 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 12 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 13 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 14 is a process diagram illustrating an attachment procedure for an optical connector. FIG. 15 illustrates another example of a method for loosening an optical fiber. FIG. 16 illustrates another example of a method for loosening an optical fiber. Fig. 17 illustrates another example of a method for slackening an optical fiber. Fig. 18 illustrates another example of a method for slackening an optical fiber. Fig. 19 illustrates another example of a method for slackening an optical fiber. Fig. 20 illustrates another example of a method for slackening an optical fiber. Fig. 21 illustrates another example of a method for slackening an optical fiber. Fig. 22 illustrates another example of a method for slackening an optical fiber. Fig. 23 illustrates another example of a method for slackening an optical fiber. Fig. 24 shows another example of the configuration of the first housing portion. Fig. 25 shows another example of the configuration of the first housing portion.

[0007] [Problem to be Solved by the Present Disclosure] When an optical connector is attached to an optical fiber cable on-site (such as a construction site) as described above, some of the components that make up the optical connector are pre-inserted into the optical fiber cable before assembling the optical connector, from the viewpoint of ease of assembly of the optical connector. However, when an optical connector is attached to an optical fiber cable outdoors, the outer jacket of the optical fiber cable is formed thick to suit outdoor environmental performance, making it difficult to pre-insert some of the components that make up the optical connector into the optical fiber cable. Furthermore, forming such components to be insertable into the optical fiber cable leads to an increase in the size of the optical connector.

[0008] An object of the present disclosure is to provide an optical connector and an optical connector mounting method that improve the ease of assembling the optical connector outdoors while suppressing an increase in size of the optical connector.

[0009] Effect of the Present Disclosure According to the present disclosure, it is possible to provide an optical connector and an optical connector mounting method that improve the ease of assembling the optical connector outdoors while preventing the optical connector from becoming large.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be described below. (1) An optical connector of the present disclosure is an optical connector to be attached to an optical fiber cable, comprising: a stub that holds a short optical fiber; a biasing member that biases the stub; a housing that accommodates a fusion splice formed by fusion splicing the short optical fiber and an optical fiber exposed from the optical fiber cable; and a cover that accommodates the stub, the biasing member, and the housing, wherein the housing has a first housing portion having a first through hole and supporting the biasing member, and a second housing portion having a second through hole and fixed to the cover, wherein the inner diameter of the first through hole in the first housing portion is smaller than the outer diameter of the optical fiber cable but larger than the outer diameter of the optical fiber of the optical fiber cable, and the inner diameter of the second through hole in the second housing portion is larger than the outer diameter of the optical fiber cable.

[0011] According to the above configuration, the second housing portion can be inserted into the optical fiber cable before assembling the optical connector, improving the ease of assembling the optical connector. Since the first housing portion is inserted into the optical fiber exposed after the outer sheath of the optical fiber cable is removed, the first housing portion does not need to be formed to match the outer diameter of the optical fiber cable and can be formed according to the size of the biasing member. Therefore, an optical connector can be provided that improves the ease of assembling the optical connector outdoors while preventing the optical connector from becoming too large.

[0012] (2) In the above (1), the first housing portion may have a slit extending along the first through hole and communicating with the first through hole.

[0013] According to the above configuration, since the optical fiber can be guided into the first through hole through the slit, it is not necessary to insert the optical fiber into the first housing portion before fusion splicing, which improves the ease of assembly of the optical connector.

[0014] (3) In the above (1) or (2), a flexible tube may be provided to house the optical fiber exposed from the optical fiber cable.

[0015] The jacket of an optical fiber cable used outdoors is thick and hard, making it difficult to route it close to the fusion splicer during fusion splicing. Therefore, a certain length of the jacket must be removed from the tip of the optical fiber cable, and the housing alone cannot accommodate the optical fiber exposed from the optical fiber cable. According to the above configuration, the flexible tube is provided, so the optical fiber exposed from the optical fiber cable can be protected.

[0016] (4) In the above (3), the optical connector may include a first connection portion connecting the cover and a first end of the flexible tube, a cable accommodating portion accommodating the optical fiber cable, a second connection portion connecting the second end of the flexible tube and the cable accommodating portion, a first sealing member arranged between the first connection portion and the first end of the flexible tube and sealing the gap between the first connection portion and the first end of the flexible tube, and a second sealing member arranged between the second connection portion and the second end of the flexible tube and sealing the gap between the second connection portion and the second end of the flexible tube.

[0017] For example, if a heat-shrinkable reinforcing tube is used to ensure waterproofing of the flexible tube, a dedicated heater is required. With the above configuration, high waterproofing can be achieved at the connection point between the end of the flexible tube and the connection part using the sealing member without using a dedicated device such as a dedicated heater.

[0018] (5) In the above (4), the optical connector may include a third sealing member disposed between the cable accommodating portion and the second connection portion, sealing the space between the cable accommodating portion and the second connection portion.

[0019] According to the above configuration, the sealing member can provide high waterproofing at the connection point between the cable housing portion and the second connection portion.

[0020] (6) In the above (4) or (5), the optical connector may include a C-shaped clamp member that holds the optical fiber cable, and the clamp member may be fixed to the second connection portion.

[0021] According to the above configuration, the clamp member is formed in a C-shape, so that it can be attached to the optical fiber cable using a general-purpose tool such as pliers without crushing the optical fiber. Furthermore, since the optical fiber cable is fixed to the optical connector by gripping the outer jacket of the optical fiber cable, the fixing operation is easier than when the optical fiber cable is fixed to the optical connector by gripping the tensile strength member of the optical fiber cable.

[0022] (7) In any one of the above (3) to (6), the length of the optical fiber housed in the flexible tube may be longer than the length of the flexible tube.

[0023] According to the above configuration, since the optical fiber is accommodated in the flexible tube in a slack state, even if the flexible tube stretches when the optical fiber cable is pulled, the optical fiber accommodated in the flexible tube can be prevented from being pulled, thereby improving the tensile strength characteristics of the optical fiber cable.

[0024] (8) A method for attaching an optical connector disclosed herein is a method for attaching an optical connector to an optical fiber cable, the optical connector including a stub for holding a short optical fiber, a first housing portion having a first through hole, and a second housing portion having a second through hole, the method comprising the steps of: inserting the optical fiber cable into the second through hole of the second housing portion; fusion-splicing the short optical fiber held in the stub to an optical fiber exposed from the optical fiber cable to form a fusion splice; inserting the optical fiber exposed from the optical fiber cable into the first through hole of the first housing portion; and attaching the first housing portion and the second housing to the stub with the fusion splice positioned in the first through hole of the first housing portion, wherein the inner diameter of the first through hole of the first housing portion is smaller than the outer diameter of the optical fiber cable and larger than the outer diameter of the optical fiber of the optical fiber cable, and the inner diameter of the second through hole of the second housing portion is larger than the outer diameter of the optical fiber cable.

[0025] According to the above method, the second housing portion can be inserted into the optical fiber cable before assembling the optical connector, improving the ease of assembling the optical connector. Since the first housing portion is inserted into the optical fiber exposed after the outer sheath of the optical fiber cable is removed, the first housing portion does not need to be formed to match the outer diameter of the optical fiber cable and can be formed according to the size of the biasing member. Therefore, an optical connector can be provided that improves the ease of assembling the optical connector outdoors while preventing the optical connector from becoming large.

[0026] (9) In the above (8), a step of accommodating the optical fiber in a loose state in a flexible tube may be included.

[0027] According to the above method, since the optical fiber is arranged in a slack state within the flexible tube, even if the flexible tube stretches when the optical fiber cable is pulled, the optical fiber housed within the flexible tube can be prevented from being pulled, thereby improving the tensile strength characteristics of the optical fiber cable.

[0028] [Details of the embodiments of the present disclosure] Specific examples of the optical connector and the method of attaching the optical connector of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0029] In the accompanying drawings, arrow F indicates the forward direction of the illustrated structure. Arrow B indicates the rearward direction of the illustrated structure. Arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. Arrow R indicates the rightward direction of the illustrated structure. Arrow L indicates the leftward direction of the illustrated structure. These directions are relative directions set for the convenience of explanation regarding the optical connector 1 shown in FIG. 1, and the tip of the optical fiber cable 30 to which the optical connector 1 is attached is considered to be the forward direction.

[0030] Fig. 1 is a perspective view illustrating the configuration of an optical connector 1 according to an embodiment of the present disclosure. Fig. 2 is an exploded perspective view of the optical connector 1. Fig. 3 is a cross-sectional view illustrating the configuration of a cross section taken along line III-III in Fig. 1 as viewed from the direction of the arrows.

[0031] As illustrated in FIG. 1, the optical connector 1 is attached to an optical fiber cable 30 by a worker outdoors.

[0032] 2, the optical connector 1 includes a stub 2, a plug frame 3, a spring coil 4, a protective sleeve 5, a housing 6, a cover 7, a flexible tube 8, a first connecting portion 9, a cable accommodating portion 10, a second connecting portion 11, and a cable holder 12. The spring coil 4 is an example of a biasing member. The cable holder 12 is an example of a clamping member.

[0033] The stub 2 holds a short optical fiber 21. Specifically, the short optical fiber 21, which has been cut to a predetermined length, is inserted into and fixed in the stub 2. The front end of the short optical fiber 21, together with the front end of the stub 2, has been subjected to end-face polishing in advance. The short optical fiber 21 extends from the rear of the stub 2. As illustrated in Fig. 3 , the short optical fiber 21 extending from the rear of the stub 2 is fusion-spliced ​​to an optical fiber 31 of an optical fiber cable 30.

[0034] The plug frame 3 holds the stub 2 so that it can move forward and backward. Specifically, as illustrated in Fig. 3 , within the plug frame 3, the stub 2 is urged forward by a spring coil 4. When the optical connector 1 is connected to a mating optical connector, the stub 2 is pushed backward and moves backward due to the contraction of the spring coil 4. The plug frame 3 is formed of a resin such as polybutylene terephthalate (PBT).

[0035] The protective sleeve 5 covers the fusion spliced ​​portion 40 formed by fusion splicing the short optical fiber 21 and the optical fiber 31 exposed from the optical fiber cable 30, thereby protecting the fusion spliced ​​portion 40. The protective sleeve 5 is formed of, for example, a heat-shrinkable resin.

[0036] The housing 6 accommodates the fusion spliced ​​portion 40 covered by the protective sleeve 5 and the optical fiber 31 extending from the fusion spliced ​​portion 40. As illustrated in Fig. 2, the housing 6 has a first housing portion 61 and a second housing portion 62. The first housing portion 61 and the second housing portion 62 are formed separately and are integrated when the optical connector 1 is assembled. The first housing portion 61 and the second housing portion 62 are each formed from a resin such as polyphenylene ether (PPE).

[0037] The cover 7 includes a main body 71, an engaging portion 72, and an O-ring 73. The main body 71 and the engaging portion 72 are each formed from a resin such as polyphenylene ether (PPE).

[0038] The main body 71 accommodates the plug frame 3 and the housing 6. A threaded portion 71T for engaging with the first connecting portion 9 is formed on the outer peripheral surface of the rear end of the main body 71. The engaging portion 72 is provided on the outer periphery of the main body 71, and a threaded portion for mating with an adapter (not shown) is formed on the outer peripheral surface. As shown in FIG. 3, the O-ring 73 is disposed between the main body 71 and the engaging portion 72. Covering the plug frame 3 and the housing 6 with the cover 7 improves the waterproofness of the optical connector 1.

[0039] The flexible tube 8 accommodates the optical fiber 31 exposed from the optical fiber cable 30. The flexible tube 8 is disposed rearward of the housing 6. The flexible tube 8 accommodates the optical fiber 31 extending rearward from the housing 6. The length of the flexible tube 8 is longer than that of the housing 6.

[0040] The optical fiber 31 is housed in a loose state within the flexible tube 8. In other words, the length of the optical fiber 31 housed within the flexible tube 8 is longer than the length of the flexible tube 8. Note that, as illustrated in Fig. 3 , when a portion of the optical fiber cable 30 from which the jacket 32 ​​has not been removed is also housed within the flexible tube 8, the length of the optical fiber 31 housed within the flexible tube 8 also includes the length of the optical fiber 31 within that portion of the optical fiber cable 30.

[0041] As shown in Fig. 2, the flexible tube 8 has a tube body 81, a first engaging portion 82, and a second engaging portion 83. The tube body 81 is, for example, a metal tube with spirally irregularities formed on its outer circumferential surface. Stainless steel, for example, is used as the metal. The tube body 81 has, for example, low tensile elongation, excellent crushing strength, and a minimum bending radius of approximately 30 mm.

[0042] The first engaging portion 82 is fixed to the front end portion 81F of the tube main body 81. For example, as illustrated in Fig. 2, a spiral convex portion 821 formed on the outer peripheral surface of the rear end portion of the first engaging portion 82 fits into a concave portion (not shown) formed on the inner peripheral surface of the front end portion 81F of the tube main body 81, thereby fixing the rear end portion of the first engaging portion 82 to the front end portion 81F of the tube main body 81. Note that the connection portion between the first engaging portion 82 and the front end portion 81F of the tube main body 81 may be covered with a weather-resistant heat-shrink tube.

[0043] The outer peripheral surface of the front end of the first engaging portion 82 has a protrusion 822 extending forward and rearward for engaging with the first connecting portion 9. In addition, an expanded diameter portion 823 with an expanded outer diameter is formed behind the protrusion 822 on the outer peripheral surface of the front end of the first engaging portion 82.

[0044] The second engaging portion 83 has the same structure as the first engaging portion 82. The second engaging portion 83 is fixed to the rear end portion 81B of the tube main body 81. For example, as illustrated in FIG. 2 , a spiral convex portion 831 formed on the outer peripheral surface of the front end portion of the second engaging portion 83 fits into a concave portion (not shown) formed on the inner peripheral surface of the rear end portion 81B of the tube main body 81, thereby fixing the front end portion of the second engaging portion 83 to the rear end portion 81B of the tube main body 81. Note that the connection portion between the second engaging portion 83 and the rear end portion 81B of the tube main body 81 may be covered with a weather-resistant heat-shrinkable tube.

[0045] The outer peripheral surface of the rear end of the second engaging portion 83 has a protrusion 832 that extends forward and rearward for engaging with the second connecting portion 11. In addition, an expanded diameter portion 833 with an expanded outer diameter is formed in front of the protrusion 832 on the outer peripheral surface of the rear end of the second engaging portion 83.

[0046] The first connecting portion 9 connects the cover 7 to a front end 8F (FIG. 1) of the flexible tube 8. The front end 8F is an example of a first end. The first connecting portion 9 includes a first engaging nut 91 and a second engaging nut 92.

[0047] The first engaging nut 91 engages with the cover 7. For example, as illustrated in Fig. 3 , a threaded portion formed on the inner peripheral surface of the front end of the first engaging nut 91 mates with a threaded portion 71T (see Fig. 2 ) formed on the outer peripheral surface of the rear end of the main body 71 of the cover 7.

[0048] The first engaging nut 91 is fixed to the first engaging portion 82. For example, a convex portion 822 formed on the outer peripheral surface of the front end of the first engaging portion 82 fits into a concave portion (not shown) formed on the inner peripheral surface of the rear end of the first engaging nut 91. The rear end of the first engaging nut 91 abuts against the front surface of an expanded diameter portion 823 of the first engaging portion 82. The fit between the convex portion 822 and the concave portion (not shown) limits the rotational movement of the first engaging nut 91 and the first engaging portion 82.

[0049] The second engagement nut 92 is disposed so as to cover the periphery of the first engagement nut 91 and the first engagement portion 82. The second engagement nut 92 engages with the first engagement nut 91. For example, as illustrated in FIG. 3, a threaded portion 91T (see FIG. 2) formed on the outer peripheral surface of the rear end portion of the first engagement nut 91 mates with a threaded portion 92T (see FIG. 2) formed on the inner peripheral surface of the front end portion of the second engagement nut 92.

[0050] 3, a step portion 921 is formed on the inner circumferential surface of the second engaging nut 92. The step portion 921 of the second engaging nut 92 abuts against the expanded diameter portion 823 (see FIG. 2) of the first engaging portion 82, thereby restricting the forward movement of the second engaging nut 92.

[0051] The cable housing 10 houses the optical fiber cable 30. As illustrated in Fig. 3, an opening 101 is formed at the rear end of the cable housing 10, and the optical fiber cable 30 extends rearward from the opening 101.

[0052] The second connecting portion 11 connects the rear end portion 8B (FIG. 1) of the flexible tube 8 to the cable housing portion 10. The rear end portion 8B is an example of a second end portion. The second connecting portion 11 includes a third engaging nut 111 and a fourth engaging nut 112.

[0053] The third engaging nut 111 engages with the cable housing 10. For example, as illustrated in Fig. 3 , a threaded portion 111T1 (see Fig. 2 ) formed on the outer peripheral surface of the rear end of the third engaging nut 111 mates with a threaded portion 10T (see Fig. 2 ) formed on the inner peripheral surface of the front end of the cable housing 10.

[0054] The third engaging nut 111 is fixed to the second engaging portion 83. For example, a convex portion 832 formed on the outer peripheral surface of the rear end portion of the second engaging portion 83 fits into a concave portion (not shown) formed on the inner peripheral surface of the front end portion of the third engaging nut 111. The fit between the convex portion 832 and the concave portion (not shown) limits the rotational movement of the third engaging nut 111 and the second engaging portion 83.

[0055] The fourth engagement nut 112 has the same structure as the second engagement nut 92. The fourth engagement nut 112 is disposed so as to cover the periphery of the third engagement nut 111 and the second engagement portion 83. The fourth engagement nut 112 engages with the third engagement nut 111. For example, as illustrated in FIG. 3 , a threaded portion 111T2 (see FIG. 2 ) formed on the outer peripheral surface of the front end of the third engagement nut 111 mates with a threaded portion (not shown) formed on the inner peripheral surface of the rear end of the fourth engagement nut 112.

[0056] 3, a step portion 1121 is formed on the inner circumferential surface of the fourth engaging nut 112. The step portion 1121 of the fourth engaging nut 112 abuts against the expanded diameter portion 833 (see FIG. 2) of the second engaging portion 83, thereby restricting rearward movement of the fourth engaging nut 112.

[0057] The cable holder 12 holds the optical fiber cable 30. As illustrated in Fig. 2, the cable holder 12 is formed so that its cross section perpendicular to the longitudinal direction is C-shaped. As illustrated in Fig. 3, the cable holder 12 is placed over the jacket 32 ​​of the optical fiber cable 30, and then crimped to reduce the diameter with a general-purpose tool such as pliers, thereby fixing the cable holder 12 to the optical fiber cable 30.

[0058] The cable holder 12 is fixed to the third engagement nut 111 in a state where it is sandwiched between the second engagement portion 83 and the third engagement nut 111. For example, as illustrated in Fig. 3, a reduced diameter portion 1111 with a reduced inner diameter is formed on the inner circumferential surface of the rear end portion of the third engagement nut 111. The cable holder 12 is disposed between the rear end of the second engagement portion 83 and the reduced diameter portion 1111 at the rear end portion of the third engagement nut 111. This restricts the movement of the cable holder 12 in the forward and rearward directions.

[0059] 2, the optical connector 1 further includes a first O-ring 13, a second O-ring 14, a third O-ring 15, and a rubber portion 16. The second O-ring 14 is an example of a first seal member. The third O-ring 15 is an example of a second seal member. The rubber portion 16 is an example of a third seal member.

[0060] The first O-ring 13 is disposed between the cover 7 and the first engaging nut 91 and provides a seal between the cover 7 and the first engaging nut 91. The second O-ring 14 is disposed between the first engaging nut 91 and the first engaging portion 82 of the flexible tube 8 and provides a seal between the first engaging nut 91 and the first engaging portion 82 of the flexible tube 8. The third O-ring 15 is disposed between the third engaging nut 111 and the second engaging portion 83 of the flexible tube 8 and provides a seal between the third engaging nut 111 and the second engaging portion 83 of the flexible tube 8.

[0061] The rubber portion 16 is disposed between the third engagement nut 111 and the cable housing 10, and seals the gap between the third engagement nut 111 and the cable housing 10. The rubber portion 16 is also disposed between the cable housing 10 and the optical fiber cable 30, and seals the gap between the cable housing 10 and the optical fiber cable 30. This prevents water and other substances from entering the cable housing 10 through the opening 101 of the cable housing 10. The rubber portion 16 also limits the rotational movement of the optical fiber cable 30 fixed to the cable holder 12.

[0062] In this example, the rubber portion 16 seals the gap between the third engaging nut 111 and the cable housing 10 and the gap between the cable housing 10 and the optical fiber cable 30. However, separate seal members may be provided between the third engaging nut 111 and the cable housing 10 and between the cable housing 10 and the optical fiber cable 30, respectively.

[0063] (First Housing Portion 61) Next, the configuration of the first housing portion 61 will be described in detail with reference to Fig. 4. Fig. 4 is a top perspective view of the first housing portion 61.

[0064] As illustrated in Fig. 4, the first housing portion 61 has a generally rectangular prism shape extending in the front and rear directions. The first housing portion 61 has a first through hole 61A extending in the front and rear directions. As illustrated in Fig. 3, the fusion splice portion 40 is housed within the first through hole 61A.

[0065] The first through hole 61A is formed so that its inner diameter D1 is smaller than the outer diameter of the optical fiber cable 30 and larger than the outer diameter of the optical fiber 31 of the optical fiber cable 30. Note that the outer diameter of the optical fiber cable 30 in this specification refers to the outer diameter of the jacket 32 ​​of the optical fiber cable 30.

[0066] The first housing portion 61 extends along the first through hole 61A and has a slit 61C that communicates with the first through hole 61A. In other words, the first housing portion 61 is formed so that its cross section in a direction perpendicular to the longitudinal direction has a C-shape. The width W of the slit 61C is formed so as to be larger than the outer diameter of the optical fiber 31 of the optical fiber cable 30.

[0067] A front end 61F of the first housing portion 61 is inserted into the plug frame 3. As illustrated in FIG. 3 , the front end 61F of the first housing portion 61 supports the spring coil 4 within the plug frame 3.

[0068] The first housing part 61 has protrusions 611 that protrude leftward and rightward at the rear end part 61B. As illustrated in Fig. 3, the protrusions 611 of the first housing part 61 abut against the rear end part of the plug frame 3. This limits the forward movement of the first housing part 61.

[0069] The first housing portion 61 has two guide portions 612 extending forward and rearward from the center of the front end portion 61F to the rear end portion 61B. A protrusion 6121 is formed at the front end of the guide portions 612. When the front end portion 61F of the first housing portion 61 is inserted into the rear end portion of the plug frame 3, the guide portions 612 of the first housing portion 61 are guided by a notch portion 3A (see FIG. 9 ) formed in the rear end portion of the plug frame 3.

[0070] (Second Housing Portion 62) Next, the configuration of the second housing portion 62 will be described in detail with reference to Fig. 5. Fig. 5 is a bottom perspective view of the second housing portion 62.

[0071] As illustrated in Fig. 5, the second housing portion 62 has a cylindrical shape that extends in the front and rear directions. In other words, the second housing portion 62 has a second through hole 62A that extends in the front and rear directions. As illustrated in Fig. 3, the second through hole 62A accommodates the optical fiber 31 extending from the fusion splice portion 40. The second through hole 62A is formed so that its inner diameter D2 is larger than the outer diameter of the optical fiber cable 30.

[0072] The rear end of the plug frame 3 and the rear end 61B of the first housing part 61 are inserted into and fixed to the front end 62F of the second housing part 62. For example, a locking claw 3B (see FIG. 9 ) formed on the outer peripheral surface of the rear end of the plug frame 3 locks into a locking groove 621 formed on the inner peripheral surface of the front end 62F of the second housing part 62. In addition, a protrusion 6121 of the first housing part 61 engages with a notch 622 recessed rearward at the front edge of the front end 62F of the second housing part 62. This restricts rotational movement of the first housing part 61 and the second housing part 62.

[0073] 3, a reduced diameter portion 623 having a reduced inner diameter is formed on the inner circumferential surface of the front end portion 62F of the second housing portion 62. The rear end portion 61B of the first housing portion 61 abuts against the reduced diameter portion 623 of the second housing portion 62, thereby restricting rearward movement of the first housing portion 61.

[0074] A plurality of protrusions 624 extending in the forward and rearward directions are formed on the outer peripheral surface of the rear end portion 62B of the second housing portion 62. The protrusions 624 of the second housing portion 62 engage with recesses (not shown) formed on the inner peripheral surface of the rear end portion of the main body portion 71 of the cover 7. This limits the rotational movement of the cover 7 and the second housing portion 62.

[0075] The second housing portion 62 is fixed to the main body portion 71 of the cover 7 in a state where it is sandwiched between the main body portion 71 of the cover 7 and the first engaging nut 91. For example, as illustrated in FIG. 5 , a stepped portion 625 is formed along the circumferential direction at the front end portion 62F of the second housing portion 62. As illustrated in FIG. 3 , the stepped portion 625 abuts against the rear surface of a reduced diameter portion 71A formed on the inner circumferential surface of the main body portion 71 of the cover 7, thereby restricting forward movement of the second housing portion 62. Furthermore, the rear end portion 62B of the second housing portion 62 abuts against the front end portion of the first engaging nut 91, thereby restricting rearward movement of the second housing portion 62.

[0076] (Method of Attaching the Optical Connector 1) Next, a method of attaching the optical connector 1 to the optical fiber cable 30 will be described. Figures 6 to 14 are process diagrams illustrating the procedure for attaching the optical connector 1.

[0077] First, as illustrated in Figure 6, at the site, from the front, the cable accommodating section 10, the rubber section 16, the third engaging nut 111, the fourth engaging nut 112, the flexible tube 8, the second engaging nut 92, the first engaging nut 91, and the second housing section 62 are passed through the optical fiber cable 30 and positioned around the outer periphery of the optical fiber cable 30.

[0078] The second engaging nut 92 and the fourth engaging nut 112 are disposed around the tube body 81 of the flexible tube 8 in advance. Specifically, after the first engaging nut 91 is passed through the tube body 81 of the flexible tube 8, the first engaging portion 82 is fixed to the front end portion 81F of the tube body 81. Similarly, after the fourth engaging nut 112 is passed through the tube body 81 of the flexible tube 8, the second engaging portion 83 is fixed to the rear end portion 81B of the tube body 81.

[0079] 7 , the jacket 32, the tension member, and the like are removed from the front end of the optical fiber cable 30, exposing the optical fiber 31 from the optical fiber cable 30. Then, the spring coil 4 and the protective sleeve 5 are passed through the optical fiber 31 from the front and disposed around the optical fiber 31.

[0080] 8, the glass fiber portion 31G obtained by stripping the coating of the optical fiber 31 exposed from the optical fiber cable 30 and the glass fiber portion 21G obtained by stripping the coating of the short optical fiber 21 in the stub 2 are butt-joined and fusion-spliced ​​using a fusion splicer. The fusion-spliced ​​portion 40 is then covered with a protective sleeve 5, and the protective sleeve 5 is then heated and shrunk.

[0081] 9 , the first housing part 61 is attached to the optical fiber 31. For example, the optical fiber 31 is inserted into the first through-hole 61A through the slit 61C of the first housing part 61. The plug frame 3 is then placed over the stub 2 from the front. The spring coil 4 is then housed in the plug frame 3, and the first housing part 61 is attached to the plug frame 3 with the spring coil 4 sandwiched between the plug frame 3 and the first housing part 61.

[0082] Next, as illustrated in FIG. 10 , the second housing portion 62 is attached to the plug frame 3 with the first housing portion 61 sandwiched between the plug frame 3 and the second housing portion 62 .

[0083] Next, as illustrated in FIG. 11 , the cover 7 is placed over the plug frame 3 and the second housing portion 62 from the front, and the cover 7 and the first engaging nut 91 are engaged with each other.

[0084] 12 , the flexible tube 8 is connected to the cover 7. Specifically, with the first engagement portion 82 of the flexible tube 8 fixed to the first engagement nut 91, the first engagement nut 91 and the second engagement nut 92 are engaged with each other.

[0085] When the second engaging nut 92 is engaged with the first engaging nut 91, the second engaging nut 92 rotates with the step portion 921 (see Figure 3) formed on the inner surface of the second engaging nut 92 abutting against the rear surface of the expanded diameter portion 823 of the first engaging portion 82, so that the first engaging portion 82 of the flexible tube 8 can engage with the first engaging nut 91 without rotating.

[0086] 13 , the cable holder 12 is fixed to the outer sheath of the optical fiber cable 30. For example, the cable holder 12 is placed over the outer sheath 32 of the optical fiber cable 30 and crimped to reduce the diameter using a general-purpose tool such as pliers, thereby fixing the cable holder 12 to the outer sheath 32 of the optical fiber cable 30.

[0087] 14 , the cable accommodation portion 10 is connected to the flexible tube 8. Specifically, with the second engagement portion 83 of the flexible tube 8 fixed to the third engagement nut 111, the third engagement nut 111 is engaged with the fourth engagement nut 112. At this time, the cable holder 12 is sandwiched and fixed between the second engagement portion 83 and the third engagement nut 111.

[0088] When the fourth engaging nut 112 is engaged with the third engaging nut 111, the fourth engaging nut 112 rotates with the step portion 1121 (see Figure 3) formed on the inner surface of the fourth engaging nut 112 abutting against the front surface of the enlarged diameter portion 833 of the second engaging portion 83, so that the second engaging portion 83 of the flexible tube 8 can engage with the third engaging nut 111 without rotating.

[0089] Then, with the rubber part 16 sandwiched between the third engaging nut 111 and the cable housing part 10, the third engaging nut 111 is engaged with the cable housing part 10. This completes the attachment of the optical connector 1 to the optical fiber cable 30.

[0090] In the above-described method of attaching the optical connector 1, the flexible tube 8, the second engaging nut 92, the first engaging nut 91, and the second housing part 62 are passed through the optical fiber cable 30 and disposed on the outer periphery of the optical fiber cable 30 in the step shown in Fig. 6. However, the flexible tube 8, the second engaging nut 92, the first engaging nut 91, and the second housing part 62 may also be passed through the optical fiber cable 30 after the protective sleeve 5 is attached to the fusion splice portion 40 by heat shrinking.

[0091] According to the optical connector 1 and the method for attaching the optical connector 1 according to the present embodiment, the second housing portion 62 is inserted into the optical fiber cable 30 before assembling the optical connector 1, improving the ease of assembly of the optical connector 1. The first housing portion 61 is inserted into the optical fiber 31 exposed after the outer sheath 32 of the optical fiber cable 30 has been removed, so the first housing portion 61 does not need to be formed to match the outer diameter of the optical fiber cable 30, but can be formed according to the size of the spring coil 4. This makes it possible to provide an optical connector 1 that improves the ease of assembly of the optical connector 1 outdoors while preventing the optical connector 1 from becoming larger.

[0092] In this embodiment, the first housing portion 61 has a slit 61C. The optical fiber 31 can be guided into the first through-hole 61A through the slit 61C, eliminating the need to insert the optical fiber 31 into the first housing portion 61 before fusion splicing. This improves the ease of assembly of the optical connector 1.

[0093] In this embodiment, the optical fiber 31 exposed from the housing 6 can be accommodated by the flexible tube 8 .

[0094] In this embodiment, the gap between the front end 8F of the flexible tube 8 and the first connecting portion 9 is sealed by a second O-ring 14. The gap between the rear end 8B of the flexible tube 8 and the second connecting portion 11 is sealed by a third O-ring 15. Therefore, high waterproofing can be achieved at the end of the flexible tube 8 without using a dedicated device such as a dedicated heater.

[0095] In addition, in this embodiment, a rubber portion 16 is arranged between the cable accommodating portion 10 and the second connection portion 11, so that high waterproofness can be obtained at the connection point between the cable accommodating portion 10 and the second connection portion 11.

[0096] In this embodiment, the cable holder 12 is formed in a C-shape, so that it can be attached to the optical fiber cable 30 using a general-purpose tool such as pliers without crushing the optical fiber 31. Furthermore, the optical fiber cable 30 is fixed to the optical connector 1 by gripping the outer sheath of the optical fiber cable 30, making the fixing operation easy.

[0097] Furthermore, in this embodiment, the first engaging portion 82 and the second engaging nut 92 of the flexible tube 8 are formed to have the same structure as the second engaging portion 83 and the fourth engaging nut 112 of the flexible tube 8. This eliminates the need to worry about the orientation of the flexible tube 8 when attaching it, improving the ease of assembly of the optical connector 1. Furthermore, because common parts can be used, parts management is easy.

[0098] In the above-described method for attaching the optical connector 1, the optical connector 1 may be assembled so that the optical fiber 31 is arranged in a loose state within the flexible tube 8.

[0099] 12 , for example, the first engaging nut 91 is temporarily fixed to the first engaging portion 82 of the flexible tube 8. For example, in the temporary fixing, a part of the first engaging portion 82 is inserted into the rear end portion of the first engaging nut 91 up to a position just before the position where the enlarged diameter portion 823 of the first engaging portion 82 abuts against the rear end portion of the first engaging nut 91.

[0100] 14 , after connecting the second connection portion 11 and the cable accommodation portion 10, the first engagement nut 91 is finally fixed to the first engagement portion 82 of the flexible tube 8. Specifically, in the final fixation, the front end portion of the first engagement portion 82 is inserted into the rear end portion of the first engagement nut 91 until the expanded diameter portion 823 of the first engagement portion 82 abuts against the rear end portion of the first engagement nut 91. Then, the second engagement nut 92 is engaged with the first engagement nut 91. This allows the optical fiber 31 to be slackened by the amount by which the front end portion of the first engagement portion 82 is inserted into the rear end portion of the first engagement nut 91 in the final fixation.

[0101] According to this method, the optical fiber 31 is accommodated in the flexible tube 8 in a loose state, so that when the optical fiber cable 30 is pulled, even if the flexible tube 8 is stretched, the optical fiber 31 accommodated in the flexible tube 8 can be prevented from being pulled.

[0102] Alternatively, the optical fiber 31 may be accommodated in a loose state in the flexible tube 8 using other methods.

[0103] 15 to 17 illustrate other examples of methods for loosening the optical fiber 31. FIG.

[0104] First, as illustrated in FIG. 15 , the cable holder 12 is fixed to the optical fiber cable 30 with a gap G provided behind the second engaging portion 83 .

[0105] 16, the third engagement nut 111 is moved forward to fix it to the second engagement portion 83. At this time, the rear end of the cable holder 12 is pushed forward by the reduced diameter portion 1111 (see FIG. 3) of the third engagement nut 111, so that the optical fiber cable 30 moves forward together with the cable holder 12. As a result, the gap G between the second engagement portion 83 and the cable holder 12 becomes smaller or disappears.

[0106] Next, as illustrated in FIG. 17 , the fourth engagement nut 112 is engaged with the third engagement nut 111 .

[0107] According to this method, the optical fiber 31 can be loosened by the amount that the optical fiber cable 30 moves forward together with the cable holder 12 by the third engagement nut 111 .

[0108] 18 to 20 illustrate another example of a method for loosening the optical fiber 31. FIG.

[0109] First, as illustrated in FIG. 18 , the cable holder 12 is fixed to the optical fiber cable 30 without leaving a gap behind the second engagement portion 83 .

[0110] 19, the third engaging nut 111 is moved forward to be fixed to the second engaging portion 83. At this time, the rear end of the cable holder 12 is pushed forward by the reduced diameter portion 1111 (see FIG. 3) of the third engaging nut 111, causing the front end of the cable holder 12 to enter the inside of the second engaging portion 83. In this example, the reduced diameter portion 1111 is formed so that its position is forward of the position of the reduced diameter portion 1111 of the third engaging nut 111 used in FIG.

[0111] Next, as illustrated in FIG. 20 , the fourth engagement nut 112 is engaged with the third engagement nut 111 .

[0112] According to this method, the optical fiber 31 can be loosened by the third engagement nut 111 by an amount corresponding to the forward movement of the optical fiber cable 30 together with the cable holder 12 .

[0113] 21 to 23 illustrate another example of a method for loosening the optical fiber 31. In this method, as illustrated in Fig. 21, a second engaging portion 83 having a notch 834 formed at the rear end portion is prepared as the second engaging portion 83.

[0114] First, as illustrated in FIG. 21 , the cable holder 12 is fixed to the optical fiber cable 30 without leaving a gap behind the second engagement portion 83 .

[0115] 22 , the cable holder 12 is rotated while being moved forward, so that a portion of the front end of the cable holder 12 is fitted into the notch 834 of the second engagement portion 83. Then, the third engagement nut 111 is moved forward to be fixed to the second engagement portion 83.

[0116] Next, as illustrated in FIG. 23, the fourth engagement nut 112 is engaged with the third engagement nut 111.

[0117] According to this method, the optical fiber 31 can be loosened by the length of the cable holder 12 fitted into the notch 834 of the second engagement portion 83 .

[0118] Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, the number, position, shape, etc. of the components described above are not limited to the above embodiments, and can be changed to the number, position, shape, etc. that are suitable for implementing the present disclosure.

[0119] In the above embodiment, the first housing portion 61 may have no slit. Fig. 24 shows another example of the configuration of the first housing portion 61. The first housing portion 161 illustrated in Fig. 24 has the same structure as the first housing portion 61 illustrated in Fig. 4, except that it does not have a slit. When assembling an optical connector 1 having such a first housing portion 161 without a slit, the optical fiber 31 is inserted into the first through hole 61A of the first housing portion 61 in the step shown in Fig. 7.

[0120] In the above embodiment, the first housing portion 61 may be composed of multiple components. FIG. 25 shows another example of the configuration of the first housing portion 61. The first housing portion 261 illustrated in FIG. 25 has the same structure as the first housing portion 161 illustrated in FIG. 24 except that it is composed of two parts. That is, the first housing portion 261 is divided into a first portion 261A and a second portion 262B along the first through hole 61A. The first portion 261A and the second portion 262B are formed to be engageable and disengageable. When assembling an optical connector 1 having such a separable first housing portion 261, in the process illustrated in FIG. 9 , for example, the first housing portion 261 is assembled by engaging the second portion 262B with the first portion 261A while the optical fiber 31 is placed in the first through hole 61A of the first portion 261A. With this configuration, it is not necessary to insert the optical fiber 31 into the first housing portion 261 before fusion splicing, thereby improving the assembly workability of the optical connector 1. The first housing portion 261 may be divided into three or more parts.

[0121] In the above embodiment, the flexible tube 8 is connected to the first connecting part 9 or the second connecting part 11 by a coupling nut system. However, the flexible tube 8 may be connected to the first connecting part 9 or the second connecting part 11 by a push-on system, a bayonet system, or the like, instead of the coupling nut system.

[0122] REFERENCE SIGNS LIST 1 Optical connector 2 Stub 3 Plug frame 3A Notch portion 3B Locking claw 4 Spring coil 5 Protective sleeve 6 Housing 7 Cover 8 Flexible tube 8B Rear end portion 8F Front end portion 9 First connection portion 10 Cable accommodating portion 10T Threaded portion 11 Second connection portion 12 Cable holder 13 First O-ring 14 Second O-ring 15 Third O-ring 16 Rubber portion 21 Short optical fiber 21G Glass fiber portion 30 Optical fiber cable 31 Optical fiber 31G Glass fiber portion 32 Jacket 40 Fusion splice portion 61 First housing portion 61A First through hole 61B Rear end portion 61C Slit 61F Front end portion 62 Second housing portion 62A Second through hole 62B Rear end portion 62F Front end portion 71 Main body portion 71A Reduced diameter portion 71T Threaded portion 71T Threaded portion 72 Engagement portion 73 O-ring 81 Tube body 81B Rear end portion 81F Front end portion 82 First engagement portion 83 Second engagement portion 91 First engagement nut 91T Threaded portion 92 Second engagement nut 92T Threaded portion 101 Opening 111 Third engagement nut 111T1 Threaded portion 111T2 Threaded portion 112 Fourth engagement nut 161 First housing portion 261 First housing portion 261A First part 262B Second part 611 Protrusion 612 Guide portion 621 Locking groove 622 Notch portion 623 Reduced diameter portion 624 Convex portion 625 Step portion 821 Convex portion 822 Convex portion 823 Enlarged diameter portion 831 Convex portion 832 Convex portion 833 Diameter expansion portion 834 Notch portion 921 Step portion 1111 Diameter reduction portion 1121 Step portion 6121 Convex portion D1 Inner diameter of first through hole D2 Inner diameter of second through hole G Gap W Slit width

Claims

1. An optical connector to be attached to an optical fiber cable, comprising: a stub that holds a short optical fiber; a biasing member that biases the stub; a housing that contains a fusion spliced ​​portion where the short optical fiber and an optical fiber exposed from the optical fiber cable are fusion spliced; and a cover that contains the stub, the biasing member, and the housing, wherein the housing has a first housing portion that has a first through hole and supports the biasing member, and a second housing portion that has a second through hole and is fixed to the cover, wherein the inner diameter of the first through hole in the first housing portion is smaller than the outer diameter of the optical fiber cable and larger than the outer diameter of the optical fiber of the optical fiber cable, and the inner diameter of the second through hole in the second housing portion is larger than the outer diameter of the optical fiber cable.

2. The optical connector according to claim 1, wherein the first housing portion has a slit extending along the first through hole and communicating with the first through hole.

3. An optical connector according to claim 1 or claim 2, further comprising a flexible tube for accommodating the optical fiber exposed from the optical fiber cable.

4. An optical connector as described in claim 3, comprising: a first connection part connecting the cover and a first end of the flexible tube; a cable accommodating part accommodating the optical fiber cable; a second connection part connecting the second end of the flexible tube and the cable accommodating part; a first sealing member disposed between the first connection part and the first end of the flexible tube, sealing the gap between the first connection part and the first end of the flexible tube; and a second sealing member disposed between the second connection part and the second end of the flexible tube, sealing the gap between the second connection part and the second end of the flexible tube.

5. An optical connector as described in claim 4, further comprising a third sealing member disposed between the cable accommodating portion and the second connecting portion, for sealing the gap between the cable accommodating portion and the second connecting portion.

6. An optical connector according to claim 4 or claim 5, further comprising a C-shaped clamp member for holding the optical fiber cable, the clamp member being fixed to the second connection portion.

7. An optical connector according to any one of claims 3 to 6, wherein the length of the optical fiber housed in the flexible tube is longer than the length of the flexible tube.

8. A method for attaching an optical connector to an optical fiber cable, the method comprising: a step of inserting the optical fiber cable through the second through hole of the second housing part; a step of fusion splicing the short optical fiber held in the stub to an optical fiber exposed from the optical fiber cable to form a fusion splice; a step of inserting the optical fiber exposed from the optical fiber cable through the first through hole of the first housing part; and a step of attaching the first housing part and the second housing to the stub with the fusion splice disposed in the first through hole of the first housing part, wherein the inner diameter of the first through hole of the first housing part is smaller than the outer diameter of the optical fiber cable and larger than the outer diameter of the optical fiber of the optical fiber cable, and the inner diameter of the second through hole of the second housing part is larger than the outer diameter of the optical fiber cable.

9. A method for attaching an optical connector according to claim 8, further comprising the step of accommodating said optical fiber exposed from said optical fiber cable in a slack state within a flexible tube.

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