Protective cover, ferrule structure, and method for manufacturing optical fiber with ferrule

Abstract

Suppress deformation of the ferrule. The shield (20) involved in the present disclosure is a shield mounted on the ferrule (10). The shield comprises: an optical fiber insertion hole (21) arranged to correspond to the arrangement of multiple optical fiber holes (12) of the ferrule, for multiple optical fibers (1) to be inserted; a lower part (22) arranged on one side with the optical fiber insertion hole as a reference; and an upper part (23) arranged on the other side with the optical fiber insertion hole as a reference. The upper part has a protrusion (231) that protrudes more than the end face of the lower part in the optical fiber insertion direction.

Description

Technical Field

[0001] The present disclosure relates to a protective cover, a ferrule structure, and a method for manufacturing an optical fiber with a ferrule.

[0002] This application claims priority based on Japanese Patent Application No. 2021-008665 filed in Japan on January 22, 2021, and the contents are incorporated herein by reference. Background Art

[0003] As a ferrule for connecting multiple optical fibers together, a so-called MT ferrule is known. Such a ferrule is provided with an adhesive filling portion. The optical fiber is fixed to the ferrule by filling the adhesive into the adhesive filling portion. For example, Patent Document 1 describes a ferrule that can be filled with adhesive from an adhesive injection port.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2003-131069

[0005] There is a concern that the ferrule may be deformed due to the shrinkage of the adhesive filled in the ferrule. In contrast, Patent Document 1 describes molding the optical fiber hole, guide pin hole, etc. of the ferrule by insert molding the resin in the metal frame. However, the structure of the ferrule described in Patent Document 1 is complicated and the manufacturing cost is high. Summary of the invention

[0006] The present invention provides a new structure capable of suppressing deformation of a ferrule.

[0007] The first embodiment of the present invention involves a shield installed on a core, and the core has a plurality of optical fiber holes arranged side by side in one direction, an adhesive filling portion filled with adhesive, and a step portion for guiding the optical fiber to the optical fiber holes, and the shield has: an optical fiber insertion hole arranged to correspond to the arrangement of the plurality of optical fiber holes for the plurality of optical fibers to be inserted; a lower portion arranged on one side with the optical fiber insertion hole as a reference; and an upper portion arranged on the other side with the optical fiber insertion hole as a reference, and the upper portion has a protrusion that protrudes more than the end face of the lower portion in the optical fiber insertion direction.

[0008] Other features of the present invention will become apparent from the following description and drawings.

[0009] According to the present invention, deformation of the ferrule can be suppressed by reducing the amount of adhesive filled in the adhesive filling portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A It is a perspective view of the ferrule structure 100 . Figure 1B It is an exploded explanatory diagram of the ferrule structure 100 .

[0011] Figure 2It is a cross-sectional perspective view of the ferrule structure 100 .

[0012] Figure 3A It is a top view of the ferrule structure 100 . Figure 3B It is a cross-sectional view of the ferrule structure 100 .

[0013] Figure 4 It is an orthographic projection diagram of the shield 20 of this embodiment in various directions.

[0014] Figure 5A and Figure 5B It is a perspective view of the shield 20 alone.

[0015] Fig. 6A It is an enlarged cross-sectional view of the vicinity of a gap between an end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10 . Figure 6B It is an explanatory diagram of the protrusion 231 of a modified example.

[0016] Fig. 7A It is an enlarged view of the vicinity of the front end of the optical fiber insertion hole 21 . Figure 7B It is an enlarged view of the vicinity of the front end of the optical fiber insertion hole 21 in a state where the optical fiber 1 is inserted therethrough.

[0017] Fig. 8A and Figure 8B It is an explanatory diagram of the exposed portion 232 .

[0018] FIG. 9A to FIG. 9D This is a diagram for explaining a method for manufacturing an optical fiber with a ferrule.

[0019] Fig. 10A It is a cross-sectional view of the ferrule structure 100 according to the second embodiment. Fig. 10B It is a partial enlarged view of the ferrule structure 100 according to the second embodiment.

[0020] Fig.11 It is an explanatory diagram of a comparative example. DETAILED DESCRIPTION

[0021] An embodiment that is an example of the invention of the present application will be described based on the description of the specification and drawings given below.

[0022] ===First Embodiment===

[0023] Figure 1A It is a perspective view of the ferrule structure 100 . Figure 1B It is an exploded explanatory diagram of the ferrule structure 100 . Figure 2 It is a cross-sectional perspective view of the ferrule structure 100 . Figure 3A It is a top view of the ferrule structure 100 . Figure 3B is a cross-sectional view of the core insert structure 100. Figure 1AIn FIG. 1 , an optical fiber ribbon composed of a plurality of optical fibers 1 is shown by dotted lines.

[0024] In the following description, each direction is defined as follows. The insertion direction of the optical fiber 1 inserted into the shield 20 (or the ferrule 10) is defined as the "optical fiber insertion direction" or the "front-rear direction", and the front end side of the optical fiber 1 is defined as the "front" and the opposite side is defined as the "rear" based on the optical fiber 1 inserted into the shield 20 (or the ferrule 10). In addition, the optical axis direction (the direction of the longitudinal axis) of the optical fiber 1 inserted into the shield 20 (or the ferrule 10) is the optical fiber insertion direction (or the front-rear direction). In addition, the direction in which the plurality of optical fibers 1 inserted into the shield 20 (or the ferrule 10) are arranged side by side, that is, the direction orthogonal to the optical axis direction (the direction of the longitudinal axis), is defined as the "width direction" or the "left-right direction", and the right side when observing the front side from the rear side is defined as the "right", and the opposite side is defined as the "left". In addition, the direction perpendicular to the optical fiber insertion direction (front-back direction) and the width direction (left-right direction), that is, the direction perpendicular to the plane formed by the optical axis direction (longitudinal axis direction) and the width direction is defined as the "upper and lower directions", and the upper side is defined as "upper" and the opposite side is defined as "lower" with reference to the optical fiber insertion hole 21 of the cover 20. In addition, there is a case where the upper side is referred to as the "filling window side" and the lower side is referred to as the "bottom side".

[0025] The ferrule structure 100 includes a ferrule 10 and a cover 20. In addition, a component in which the optical fiber 1 is fixed to the ferrule structure 100 may be referred to as an optical fiber with a ferrule.

[0026] The ferrule 10 is a component that holds the ends of a plurality of optical fibers 1. The ferrule 10 of the present embodiment is an MT connector (MT ferrule) specified in JIS C 5981 and IEC 61754-5. The main body of the ferrule 10 has a connection end face 10A and an outer wall. The connection end face 10A is the end face on the front side of the ferrule 10, and is the end face connected to the counterpart ferrule (not shown here). The outer wall constitutes the outer surface connected to the connection end face 10A (mainly the upper and lower and left and right outer surfaces of the main body of the ferrule 10). A pair of guide holes 11 are provided on the left and right of the ferrule 10. In addition, a flange portion 10B (flange portion) protruding outward from the side of the main body of the ferrule 10 is provided at the rear of the ferrule 10.

[0027] The ferrule 10 of the present embodiment includes a plurality of optical fiber holes 12 , an adhesive-filled portion 13 , an inner wall 14 , a step portion 15 , and a boot insertion port 17 .

[0028] The optical fiber hole 12 is a hole for inserting the end of the optical fiber 1. The end of the optical fiber 1 is fixed to each optical fiber hole 12. A plurality of optical fiber holes 12 are arranged side by side in the width direction (arranged side by side in one direction). Here, 24 optical fiber holes 12 are arranged side by side in one row in the width direction. However, the number of optical fiber holes 12 is not limited to 24. In addition, the row of optical fiber holes 12 can be either one row or two or more rows. One end (rear end) of the optical fiber hole 12 opens at the inner wall 14 (more specifically, the first surface 14A) of the adhesive filling portion 13. The other end (front end) of the optical fiber hole 12 opens at the connecting end surface 10A of the ferrule 10. In addition, the optical fiber hole 12 is connected to the guide groove 15A described later.

[0029] The adhesive filling portion 13 is a portion (space) filled with adhesive. An upper opening 131 (adhesive filling window) is provided on the upper surface of the ferrule 10. The upper opening 131 is an opening that passes from the outer wall of the ferrule 10 to the adhesive filling portion 13. The adhesive is filled into the adhesive filling portion 13 from the upper opening 131. In addition, a lower opening 132 is provided on the lower surface of the ferrule 10. The lower opening 132 is an opening that passes from the outer wall of the ferrule 10 to the adhesive filling portion 13. The lower opening 132 is arranged on the side opposite to the upper opening 131. As described later, by providing openings on the upper and lower surfaces of the ferrule 10, deformation of the ferrule 10 caused by shrinkage accompanying the curing of the adhesive can be suppressed. However, the lower opening 132 may not be provided on the lower surface of the ferrule 10. The optical fiber hole 12 opens on the inner wall surface (first surface 14A) on the front side of the adhesive filling portion 13. Furthermore, a pressing portion 131A is provided on the upper wall surface of the adhesive-filled portion 13 .

[0030] The inner wall 14 has a plurality of openings of the optical fiber holes 12, and is arranged in the body of the ferrule 10. The space arranged on the side opposite to the connection end face 10A with respect to the inner wall 14 is the adhesive filling portion 13. That is, the inner wall 14 is a wall surface on the connection end face 10A side (the front side of the adhesive filling portion 13; the side where the optical fiber hole 12 opens) among the wall surfaces constituting the adhesive filling portion 13. In the present embodiment, the inner wall 14 has a first surface 14A and a second surface 14B. The first surface 14A is a surface along the edge of the connection end face 10A side (front side) in the upper opening 131. The upper opening 131 opens at a position along the first surface 14A. The second surface 14B is a surface protruding further toward the adhesive filling portion 13 side (rear side) than the first surface 14A, and is the rear end surface of the step portion 15. In the first embodiment, the second surface 14B is a surface along the edge of the connection end face 10A side (front side) in the lower opening 132. The lower opening 132 opens at a position along the second surface 14B.

[0031] The step portion 15 is a step provided inside the adhesive filling portion 13, and guides the optical fiber 1 to the optical fiber hole 12. A plurality of guide grooves 15A are provided on the upper surface of the step portion 15. The guide groove 15A is a groove for guiding the optical fiber 1 to the optical fiber hole 12. The guide groove 15A is a groove along the optical fiber insertion direction (front-rear direction). The plurality of guide grooves 15A are arranged side by side in the width direction. Here, the guide groove 15A is composed of a circular groove with a semicircular cross section. However, the guide groove 15A may be other shapes such as a V-groove, a circular groove with a semicircular cross section, a U-groove, or a square groove. In addition, the guide groove 15A may not be provided on the upper surface of the step portion 15. The front end of the guide groove 15A reaches the inner wall 14 (more specifically, the first surface 14A) on the front side of the adhesive filling portion 13. The front end of the guide groove 15A is connected to the opening of the optical fiber hole 12. The rear end of the guide groove 15A reaches the second surface 14B which becomes the rear end surface of the step portion 15. The rear end surface (second surface 14B) of the step portion 15 is formed of a surface perpendicular to the optical fiber insertion direction. The second surface 14B functions as a positioning surface for positioning the cover 20 in the mounting direction (front-rear direction).

[0032] The guide groove 15A is provided on the upper surface of the step portion 15 (the surface on the upper opening 131 side). Therefore, if there is no shield 20 inside the adhesive filling portion 13, when the operator inserts the optical fiber 1 into the optical fiber hole 12, the operator can confirm the inside of the adhesive filling portion 13 from the upper opening 131 while confirming the situation that the end of the optical fiber 1 is guided through the guide groove 15A. However, in the present embodiment, as described later, the end of the shield 20 is inserted into the inside of the adhesive filling portion 13, and a part of the upper opening 131 is blocked by the upper surface of the shield 20 (see Figure 1A , Figure 2 , Figure 3B ).

[0033] The shield insertion port 17 is an opening for inserting the shield 20. The shield insertion port 17 is provided at the rear end of the ferrule 10. The shield insertion port 17 is communicated with the adhesive filling portion 13. The shield insertion port 17 allows a plurality of optical fibers 1 to be inserted therethrough. The optical fibers 1 inserted from the shield insertion port 17 pass through the adhesive filling portion 13 and are inserted into the optical fiber hole 12. In addition, in the present embodiment, the shield insertion port 17 is communicated with the adhesive filling portion 13 so that the end of the shield 20 is inserted into the interior of the adhesive filling portion 13.

[0034] Fig.11 It is an explanatory diagram of a comparative example.

[0035] like Fig.11 As shown, the shield 20 is usually mounted on the shield insertion port 17 in a manner that does not allow the end portion to reach the adhesive filling portion 13. Fig.11As shown, the shield is configured to block the rear portion of the adhesive filling portion 13. Thus, the adhesive is prevented from leaking from the rear end of the ferrule 10. In the case of the comparative example, there is a concern that the ferrule 10 may be deformed due to the shrinkage of the adhesive filled in the adhesive filling portion 13 as it cures. In order to suppress the deformation of the ferrule 10 caused by the shrinkage of the adhesive, it is preferable to reduce the amount of adhesive filled in the adhesive filling portion 13. On the other hand, there is a concern that the fixation of the optical fiber 1 may become insufficient if the amount of adhesive is simply reduced.

[0036] Therefore, in this embodiment, if Figure 2 and Figure 3B As shown, a part of the shield 20 (specifically, the protrusion 231) is arranged opposite to the upper surface of the step portion 15. As a result, the adhesive required for fixing the optical fiber 1 can be applied around the optical fiber 1 while reducing the amount of adhesive filled in the adhesive filling portion 13. This point will be described below.

[0037] Figure 4 It is an orthographic projection diagram of the shield 20 of this embodiment in various directions. Figure 5A and Figure 5B It is a perspective view of the shield 20 alone.

[0038] The shield 20 is a component for protecting the optical fiber 1. The shield 20 is made of a flexible material (such as resin) and can be elastically deformed. Therefore, the shield 20 can suppress the load (such as bending stress) applied to the plurality of optical fibers 1. Figure 2 and Figure 3B As shown, when the shield 20 is mounted on the ferrule 10, the center portion of the shield 20 in the optical fiber insertion direction (front-rear direction) is arranged to be sandwiched by the upper and lower inner wall surfaces of the ferrule 10. Figure 2 and Figure 3B As shown in FIG. 1 , the front portion of the shield 20 (the portion closer to the front side than the portion sandwiched by the upper and lower inner wall surfaces of the ferrule 10) is arranged inside the adhesive filling portion 13. In addition, the portion closer to the rear side than the portion sandwiched by the upper and lower inner wall surfaces of the ferrule 10 protrudes further to the rear side than the ferrule 10, and serves as a portion (strain relief) for suppressing bending stress applied to the optical fiber 1.

[0039] The protective cover 20 has an optical fiber insertion hole 21. The optical fiber insertion hole 21 is a through hole for inserting a plurality of optical fibers 1. Therefore, the optical fiber insertion hole 21 is configured as a through hole along the optical fiber insertion direction (front-back direction; optical axis direction of the optical fiber 1). In addition, the optical fiber insertion hole 21 is configured to be able to insert an optical fiber ribbon composed of a plurality of optical fibers 1. Therefore, the optical fiber insertion hole 21 is configured as a cross-sectional shape extending in the width direction (left-right direction).

[0040] The optical fiber insertion hole 21 is arranged to correspond to the arrangement of the optical fiber hole 12 of the ferrule 10. Therefore, the optical fiber insertion hole 21 is arranged to be at the same height as the optical fiber hole 12 of the ferrule 10 and the upper surface of the step portion 15 (or the guide groove 15A) when the cover 20 is attached to the ferrule 10.

[0041] The shield 20 has a lower portion 22 and an upper portion 23. The shield 20 is formed by connecting two block-shaped lower portions 22 and upper portions 23 at both ends in the width direction. In the following description, the portion connecting the lower portion 22 and the upper portion 23 outside the optical fiber insertion hole 21 in the width direction is sometimes referred to as a connecting portion 24. The space surrounded by the lower portion 22, the upper portion 23, and the pair of connecting portions 24 is the optical fiber insertion hole 21.

[0042] The lower portion 22 is arranged on one side (lower side, bottom side) with the optical fiber insertion hole 21 as a reference. In other words, the lower portion 22 is arranged on the side opposite to the upper opening 131 of the ferrule 10 when the shield 20 is mounted on the ferrule 10. The lower portion 22 is a block-shaped (plate-shaped) portion constituting the lower side of the shield 20, and is sometimes referred to as a "lower block" or a "first block". The lower portion 22 is arranged at the bottom (lower) of the adhesive filling portion 13 to fill the space on the bottom side of the adhesive filling portion 13. In addition, a lower opening 132 is provided on the lower surface of the ferrule 10 of the present embodiment. However, in the case of a ferrule 10 assuming no lower opening 132, the lower portion 22 is arranged to be opposite to the bottom surface of the ferrule 10 (the bottom surface of the adhesive filling portion 13).

[0043] The front end surface 22A of the lower portion 22 is formed of a surface perpendicular to the optical fiber insertion direction (the direction in which the shield 20 is installed; the front-back direction). The front end surface 22A of the lower portion 22 is a contact surface that contacts the second surface 14B (the rear end surface of the step portion 15) of the inner wall 14 of the ferrule 10, and functions as an alignment surface for aligning the shield 20 in the installation direction (the front-back direction).

[0044] The upper portion 23 is arranged on the other side (lower side, bottom side; the side opposite to the lower portion 22 side) with the optical fiber insertion hole 21 as a reference. In other words, the upper portion 23 is arranged on the upper opening 131 side of the ferrule 10 when the shield 20 is mounted on the ferrule 10. The upper portion 23 is a block-shaped (plate-shaped) portion constituting the upper side of the shield 20, and is sometimes referred to as an "upper block" or a "second block". The upper portion 23 fills the space on the upper side of the adhesive filling portion 13.

[0045] The upper portion 23 has a protrusion 231. The protrusion 231 protrudes in the direction of the optical fiber insertion than the end face 22A of the lower portion 22. The protrusion 231 is arranged at the end of the front side of the upper portion 23. The optical fiber insertion hole 21 is arranged to correspond to the arrangement of the optical fiber hole 12 of the ferrule 10. In addition, the protrusion 231 protrudes further to the front side than the end face 22A of the lower portion 22 (the portion below the optical fiber insertion hole 21). Thus, in a state where the shield 20 is mounted on the ferrule 10, the protrusion 231 is opposed to the upper surface of the step portion 15 (or the guide groove 15A) inside the adhesive filling portion 13. That is, the lower surface of the protrusion 231 becomes an opposing surface opposed to the upper surface of the step portion 15. Protrusion 231 is disposed inside adhesive-filled portion 13 to face the upper surface of step portion 15 , so that upper portion 23 can fill a space of adhesive-filled portion 13 on the upper opening 131 side (upper side) than step portion 15 .

[0046] Fig. 6A 2 is an enlarged cross-sectional view of the gap between the end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10. Fig. 6A yes Figure 3B An enlarged illustration of area A.

[0047] The end face 231A of the protrusion 231 is arranged opposite to the first face 14A having the opening of the optical fiber hole 12. Since the protrusion 231 protrudes from the lower portion 22, the gap between the end face 231A of the hood 20 (protrusion 231) and the first face 14A can be reduced compared to the case where the protrusion 231 is not provided on the hood 20. The gap between the end face 231A of the protrusion 231 and the first face 14A opens upward at the upper opening 131. The adhesive is filled from this gap. If the adhesive is filled from the gap opened in the upper opening 131 (the gap between the end face 231A of the protrusion 231 and the first face 14A), it penetrates into the interior by capillary phenomenon (described later).

[0048] In this embodiment, the length of the protrusion 231 protruding from the end surface 22A of the lower portion 22 is ( Fig. 7A The protruding length L2 shown; the dimension between the end surface 22A of the upper portion 22 and the end surface 231A of the upper portion 23 in the direction of optical fiber insertion) is greater than the length of the step portion 15 in the direction of optical fiber insertion ( Fig. 7A The length L1 shown in the figure; the length of the guide groove 15A; the dimension between the first surface 14A and the second surface 14B in the direction of the optical fiber insertion). That is, the protruding length L2 of the protruding portion 231 is smaller than the length L1 of the step portion 15 in the direction of the optical fiber insertion (L2<L1). As a result, when the end surface 22A of the lower portion 22 of the shield 20 is in contact with the second surface 14B of the step portion 15 (refer to Figure 2 and Figure 3B ),like Fig. 6AAs shown, a gap for filling the adhesive can be formed between the end face 231A of the protrusion 231 and the first surface 14A of the ferrule 10. In the present embodiment, the protrusion length L2 of the protrusion 231 is smaller than the length L1 of the step portion 15 in the optical fiber insertion direction (L2<L1), so that the shroud 20 can be aligned with respect to the installation direction (front-rear direction) of the ferrule 10 by bringing the end face 22A of the lower portion 22 of the shroud 20 into contact with the second surface 14B of the step portion 15.

[0049] However, if Fig. 6A (and Figure 2 ), a pressing portion 131A is provided on the wall surface on the upper side of the adhesive filling portion 13 of the ferrule 10. The pressing portion 131A presses the protrusion 231 of the shield 20 from the upper side. The pressing portion 131A is provided at both ends in the width direction near the front edge of the upper opening 131. When the shield 20 is mounted on the ferrule 10, the pressing portion 131A is arranged on the upper side of the two edges (two corners) in the width direction of the protrusion 231 of the shield 20. In other words, the protrusion 231 of the shield 20 is configured to be arranged on the lower side of the wall surface (pressing portion 131A) on the upper side of the adhesive filling portion 13 of the ferrule 10. The pressing portion 131A is arranged on the upper side of the protrusion 231 of the shield 20, so that the protrusion 231 of the shield 20 can be suppressed from being displaced upward inside the adhesive filling portion 13, and the protrusion 231 is stably arranged inside the adhesive filling portion 13. In addition, the pressing portion 131A is provided only on the upper sides of both edges in the width direction of the protruding portion 231 of the shield 20, and is not provided on the upper side of the central portion in the width direction of the protruding portion 231. Fig. 6A As shown, the upper part of the gap between the end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10 can be opened, and the adhesive can be filled from the gap. In addition, the ferrule 10 does not need to include the pressing portion 131A.

[0050] Figure 6B It is an explanatory diagram of the protrusion 231 of a modified example.

[0051] The protrusion 231 of the modified example has an inclined surface 231B between the upper surface of the protrusion 231 (the surface on the upper opening 131 side) and the end surface 231A of the protrusion 231. That is, the protrusion 231 of the modified example has an inclined surface 231B at the upper edge of the end surface 231A. As a result, it is easy to fill the adhesive between the end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10. In addition, as Figure 6B As shown, even when the protrusion 231 is provided with the inclined surface 231B, it is preferable that the pressing portion 131A of the ferrule 10 presses the protrusion 231 of the shield 20 from above.

[0052] Fig. 7A It is an enlarged view of the vicinity of the front end of the optical fiber insertion hole 21 . Figure 7B This is an enlarged view of the vicinity of the front end of the optical fiber insertion hole 21 in a state where the optical fiber 1 is inserted. Fig. 7A yes Figure 3B An enlarged illustration of region B.

[0053] like Figure 7B As shown, the optical fiber insertion hole 21 is formed to be suitable for the diameter of the optical fiber 1 having a cladding. For example, the diameter of the optical fiber 1 (the outer diameter of the cladding) is 250 μm, and the dimension of the optical fiber insertion hole 21 in the vertical direction (the interval between the lower portion 22 and the upper portion 23) is 260 μm. Therefore, the position of the lower surface of the upper portion 23 in the vertical direction becomes almost the same position as the upper edge of the optical fiber 1 (the optical fiber 1 having a cladding) inserted into the optical fiber insertion hole 21. The front end portion (the end on the front side) of the optical fiber 1 is a bare optical fiber from which the cladding has been removed. For example, the diameter of the bare optical fiber is 125 μm. The stripped edge 1A of the cladding (the front end of the cladding of the optical fiber 1) is arranged on the rear side (the side of the shield insertion port 17) of the second surface 14B (or the guide groove 15A) of the step portion 15. Therefore, as Figure 7B As shown, the stripped edge 1A of the cladding is arranged inside the optical fiber insertion hole 21. In addition, the bare optical fiber is extended toward the front side from the opening of the optical fiber insertion hole 21. In addition, the bare optical fiber is arranged on the upper surface of the step portion 15 (the guide groove 15A).

[0054] like Fig. 7A As shown in FIG. 1 , the lower surface of the protrusion 231 becomes an opposing surface to the upper surface of the step portion 15. Fig. 7A As shown in FIG. 1 , the lower surface of the protrusion 231 is provided on the extension of the upper edge of the optical fiber insertion hole 21. The optical fiber insertion hole 21 is formed to be suitable for the diameter of the optical fiber 1 having the cladding. Therefore, as in the present embodiment, the lower surface of the protrusion 231 (the opposite surface to the upper surface of the step portion 15) is provided on the extension of the upper edge of the optical fiber insertion hole 21, so that Fig. 7A As shown in FIG. 1 , a gap corresponding to the diameter of the clad optical fiber 1 is formed between the lower surface of the protrusion 231 and the upper surface of the step portion 15 (here, the guide groove 15A). Figure 7B As shown, if a bare fiber is placed between the lower surface of the protrusion 231 and the upper surface (guide groove 15A) of the step portion 15, a narrow gap of the thickness of the cladding is formed around the bare fiber. As a result, the adhesive easily penetrates around the bare fiber by capillary action.

[0055] like Figure 7B As shown in FIG. 1 , the stripped edge 1A of the cladding is arranged on the rear side (the shield insertion port 17 side) of the second surface 14B (or the guide groove 15A) of the step portion 15, and is therefore located inside the optical fiber insertion hole 21. As a result, Figure 3BAs shown, when the ferrule structure 100 is viewed from above, the stripped edge 1A of the cladding is hidden by the upper portion 23 of the cover 20, and the position of the stripped edge 1A of the cladding in the optical fiber insertion direction (front-back direction) cannot be confirmed from the upper opening 131. Therefore, as described below, it is preferred that an exposed portion 232 is provided in the cover 20.

[0056] Fig. 8A and Figure 8B It is an explanatory diagram of the exposed portion 232 .

[0057] Fig. 8A and Figure 8B The shield 20 shown has an exposed portion 232. The exposed portion 232 exposes the upper portion of the optical fiber 1 inserted into the optical fiber insertion hole 21. The exposed portion 232 is arranged on the rear side of the end surface 22A on the front side of the lower portion 22. That is, when the shield 20 is mounted on the ferrule 10, the exposed portion 232 is arranged on the rear side of the second surface 14B (or the guide groove 15A) of the step portion 15. In addition, when the shield 20 is mounted on the ferrule 10, the exposed portion 232 is arranged on the front side of the rear edge of the upper opening 131. When the shield 20 is mounted on the ferrule 10, the exposed portion 232 is arranged between the second surface 14B (or the guide groove 15A) of the step portion 15 and the rear edge of the upper opening 131, so that Fig. 8A and Figure 8B As shown, the position of the stripped edge 1A of the cladding in the optical fiber insertion direction (front-rear direction) can be confirmed from the upper opening 131 through the exposed portion 232 .

[0058] Furthermore, the exposed portion 232 may be shaped so as to expose the upper part of a portion of the plurality of optical fibers 1 inserted into the optical fiber insertion hole 21. This is because, when removing the cladding of the optical fiber ribbon in such a manner that the positions of the stripped edges 1A of the cladding of the optical fibers 1 are aligned, it is sufficient to confirm the positions of the stripped edges 1A of the cladding of a portion of the optical fibers 1 in the direction of optical fiber insertion. Therefore, the exposed portion 232 does not need to expose the upper parts of all the optical fibers 1.

[0059] like Fig. 8A As shown, the exposed portion 232 can be formed by a recessed portion provided at an end portion in the width direction of the shield 20. Fig. 8A The exposed portion 232 shown in the figure can confirm the position of the stripped edge 1A of the cladding of the optical fiber 1 located at the end of the width direction of the optical fiber insertion hole 21 in the optical fiber insertion direction. Fig. 8A As shown, it is preferable to provide recessed portions at both ends in the width direction. Thus, the position of the stripped edge 1A of the cladding of the optical fiber 1 located at both ends in the width direction in the direction of insertion of the optical fiber can be confirmed, and as a result, it can be inferred that the stripped edge 1A of the other optical fiber 1 (the optical fiber 1 located in the center in the width direction) is located on the line connecting the stripped edges 1A at both ends.

[0060] like Figure 8B As shown, the exposed portion 232 can be formed by a window (opening) provided in the center portion in the width direction of the shield 20. Figure 8B The exposed portion 232 shown can confirm the position of the stripped edge 1A of the cladding of the optical fiber 1 located in the center of the width direction of the optical fiber insertion hole 21 in the optical fiber insertion direction. Figure 8B As shown, by providing the exposed portion 232 at the center of the width direction of the protective cover 20, the stripped edge 1A of the cladding of the optical fiber 1 can be confirmed at the center of the width direction of the upper opening 131, so that the operator can easily perform the confirmation operation. Figure 8B As shown, by providing the exposed portion 232 at the center portion in the width direction of the shield 20 , it is easy to arrange the protruding portion 231 of the shield 20 under the pressing portion 131A of the ferrule 10 .

[0061] like Figure 1A and Figure 1B As shown in FIG. 1 , the shield 20 of this embodiment has a recess 20A. The recess 20A is a depression provided at the rear portion of the shield 20. Figure 3A As shown, when the shield 20 is mounted on the ferrule 10, the recess 20A is located on the front side of the rear end face of the ferrule 10. Therefore, when the adhesive filled in the adhesive filling portion 13 penetrates into the inside of the ferrule 10 (described later), even if the adhesive penetrates between the shield insertion port 17 of the ferrule 10 and the shield 20, it is possible to suppress the adhesive from leaking to the rear side of the rear end face of the ferrule 10. However, the shield 20 may not have the recess 20A.

[0062] <Manufacturing method>

[0063] FIG. 9A to FIG. 9D This is a diagram for explaining a method for manufacturing an optical fiber with a ferrule.

[0064] First, the operator prepares the ferrule 10 and the cover 20. As already described, the ferrule 10 includes: a plurality of optical fiber holes 12 arranged side by side in one direction; an adhesive filling portion 13 filled with adhesive; and a step portion 15 for guiding the optical fiber 1 to the optical fiber hole 12. As already described, the cover 20 includes: an optical fiber insertion hole 21, a lower portion 22 arranged on one side of the optical fiber insertion hole 21, and an upper portion 23 arranged on the other side of the optical fiber insertion hole 21. The upper portion 23 has a protrusion 231 that protrudes from the end surface 22A of the lower portion 22 in the optical fiber insertion direction.

[0065] In addition, the operator pre-processes the plurality of optical fibers 1. For example, as pre-processing of the optical fibers 1, the operator removes the cladding of the optical fiber ribbon (removes the cladding of each of the plurality of optical fibers 1) and cuts the bare optical fibers into a predetermined length.

[0066] Next, if Fig. 9A As shown, the operator inserts the plurality of optical fibers 1 (optical fiber ribbon) into the optical fiber insertion holes 21 of the protective cover 20. In addition, the operator inserts the plurality of optical fibers 1 (optical fiber ribbon) into the protective cover 20 in such a manner that the front ends of the optical fibers 1 (bare optical fibers) protrude further forward than the protrusions 231 of the protective cover 20.

[0067] In addition, if Fig. 9A As shown in the figure, the operator applies the adhesive to the vicinity of the opening of the optical fiber hole 12 on the side of the adhesive filling portion 13, and applies the adhesive to the optical fiber hole 12. Alternatively, after applying the adhesive to the vicinity of the opening of the optical fiber hole 12 on the side of the adhesive filling portion 13, the operator may suck the adhesive from the connection end surface 10A side of the ferrule 10, thereby applying the adhesive to the inside of the optical fiber hole 12. By applying the adhesive to the optical fiber hole 12 in advance, it is possible to suppress the mixing of bubbles into the inside of the optical fiber hole 12.

[0068] Next, if Fig. 9B As shown, the operator inserts the plurality of optical fibers 1 inserted through the cover 20 into the respective fiber holes 12 of the ferrule 10. At this time, the operator inserts the optical fibers 1 into the fiber holes 12 while guiding the optical fibers 1 using the upper surface of the step portion 15 of the ferrule 10 (here, the guide groove 15A).

[0069] Next, if Fig. 9C As shown, the operator inserts the shield 20 into the shield insertion port 17 of the ferrule 10 and installs the shield 20 on the ferrule 10. Fig. 9C As shown in FIG. 1 , the operator inserts the shield 20 into the ferrule 10 until the end surface 22A of the lower portion 22 of the shield 20 contacts the second surface 14B of the step portion 15 of the ferrule 10. When the end surface 22A of the lower portion 22 of the shield 20 contacts the second surface 14B of the step portion 15 of the ferrule 10, a gap for filling the adhesive is formed between the end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10. In addition, the lower surface of the protrusion 231 is arranged to face the upper surface of the step portion 15 with a gap of the diameter of the optical fiber 1 (see FIG. 1 ). Fig. 7A and Figure 7B ).

[0070] At this time, the operator arranges the two edges (two corners) of the width direction of the protruding portion 231 of the shield 20 to be located below the upper wall surface (pressing portion 131A) of the adhesive filling portion 13 of the ferrule 10. Fig. 8A and Figure 8B ), after installing the protective cover 20 on the ferrule 10, the operator can confirm the position of the stripped edge 1A of the cladding in the optical fiber insertion direction (front-back direction) from the upper opening 131 through the exposed portion 232.

[0071] Next, if Fig.9DAs shown, the operator applies adhesive to the gap between the end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10. The adhesive applied to the gap penetrates into the inside by capillary phenomenon, and the adhesive is applied to the guide groove 15A and the periphery of the optical fiber 1 arranged in the guide groove 15A. After the adhesive is applied, the optical fiber 1 is fixed to the ferrule 10 by curing the adhesive, and the manufacture of the optical fiber with the ferrule is completed.

[0072] In this embodiment, the shield 20 is disposed inside the adhesive filling portion 13 , so that the amount of adhesive filled in the adhesive filling portion 13 can be reduced. As a result, even if the adhesive shrinks when curing, deformation of the ferrule 10 can be suppressed.

[0073] On the other hand, in the present embodiment, the protrusion 231 is provided on the shield 20, so that the gap between the protrusion 231 of the shield 20 and the first surface 14A of the ferrule 10 can be reduced, and the adhesive can easily penetrate into the inside by capillary phenomenon. In addition, in the present embodiment, the gap between the lower surface of the protrusion 231 and the upper surface of the step portion 15 (or the guide groove 15A) can be reduced, and the gap around the optical fiber 1 (bare optical fiber) arranged on the upper surface of the step portion 15 can be reduced, so that the adhesive can easily penetrate into the upper surface of the step portion 15 and the surrounding of the optical fiber 1 arranged on the upper surface of the step portion 15 by capillary phenomenon. As described above, in the present embodiment, even if the amount of adhesive is small, the adhesive can be applied to the upper surface of the step portion 15 and the surrounding of the optical fiber 1, and the optical fiber can be fixed to the ferrule with sufficient strength.

[0074] ===Second Embodiment===

[0075] Fig. 10A It is a cross-sectional view of the ferrule structure 100 according to the second embodiment. Fig. 10B : is a partial enlarged view of the insert structure 100 of the second embodiment. Fig. 10B yes Fig. 10A An enlarged illustration of region C.

[0076] In the second embodiment, the ferrule structure 100 also includes a ferrule 10 and a protective cover 20. In addition, in the second embodiment, the ferrule 10 also includes a plurality of optical fiber holes 12, an adhesive filling portion 13, and a step portion 15 provided with a plurality of guide grooves 15A. In the second embodiment, the ferrule 10 has two rows (optical fiber rows) of a plurality of optical fiber holes 12 arranged side by side in one direction (vertical direction of the paper in the figure). The two optical fiber rows are arranged in the vertical direction. The plurality of optical fibers 1 of the optical fiber ribbon are inserted into the plurality of optical fiber holes 12 of each optical fiber row. In the second embodiment, the plurality of optical fibers 1 are fixed to the ferrule 10 in a state where two optical fiber ribbons are overlapped.

[0077] The step portion 15 has two rows (guide groove rows) of a plurality of guide grooves 15A arranged side by side in one direction (vertical to the paper surface in the figure). The two guide groove rows are configured in a stepped shape. Regardless of which guide groove row, the front end of the guide groove 15A reaches the inner wall 14 on the front side of the adhesive filling portion 13. In addition, regardless of which guide groove row, the front end of the guide groove 15A is connected to the opening of the optical fiber hole 12. The rear end of the guide groove 15A of the lower guide groove row reaches the second surface 14B of the step portion 15. On the other hand, the rear end of the guide groove 15A of the lower guide groove row is set to the central part of the optical fiber insertion direction of the step portion 15, and does not reach the second surface 14B. In addition, in the second embodiment, there may be no guide groove 15A on the upper surface of the step portion 15.

[0078] In the second embodiment, the protective cover 20 also includes a fiber insertion hole 21, a lower portion 22, and an upper portion 23. The upper portion 23 has a protrusion 231 that protrudes more than the end surface 22A of the lower portion 22 in the fiber insertion direction. In the second embodiment, the fiber insertion hole 21 is also configured to correspond to the configuration of the fiber hole 12 of the ferrule 10. In the second embodiment, two optical fiber ribbons in an overlapping state are inserted into the optical fiber insertion hole 21. Therefore, in the second embodiment, the optical fiber insertion hole 21 is formed to be suitable for two optical fiber ribbons in an overlapping state. In addition, the vertical dimension of the optical fiber insertion hole 21 (the interval between the lower portion 22 and the upper portion 23) is equivalent to the thickness of the two optical fiber ribbons. In addition, in the case where the two optical fiber ribbons are configured to be separated in the vertical direction and the two optical fiber rows of the ferrule 10 are configured to be relatively separated in the vertical direction, two optical fiber insertion holes 21 separated in the vertical direction can also be provided in the protective cover 20. In the second embodiment, the adhesive is also applied to the gap between the end surface 231A of the protrusion 231 and the first surface 14A of the ferrule 10 , and the adhesive applied to the gap permeates into the inside by capillary phenomenon.

[0079] In the second embodiment, the lower surface of the protrusion 231 also becomes an opposing surface to the upper surface of the step portion 15 (here, the guide groove 15A). In addition, in the second embodiment, the lower surface of the protrusion 231 is also arranged on the extension line of the upper edge of the optical fiber insertion hole 21. Therefore, in the second embodiment, a gap equivalent to the diameter of the optical fiber 1 with cladding is also formed between the lower surface of the protrusion 231 and the upper surface of the upper layer of the step portion 15 (the upper guide groove 15A). In addition, in the second embodiment, the gap between the lower surface of the protrusion 231 and the upper surface of the lower layer of the step portion 15 (the lower guide groove 15A) becomes relatively large. However, a plurality of optical fibers 1 (bare optical fibers) arranged in two rows in the upper and lower directions are arranged between the lower surface of the protrusion 231 and the upper surface of the lower layer of the step portion 15, and a narrow gap of the thickness of the cladding is formed around these bare optical fibers. Therefore, in the second embodiment, the adhesive is also easy to penetrate around the bare optical fiber by capillary phenomenon.

[0080] ===Other Implementation Methods===

[0081] The above-mentioned embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention naturally includes equivalents thereof.

[0082] Description of Reference Numerals

[0083] 1…optical fiber; 1A…stripping edge; 10…insertion core; 10A…connection end face; 10B…flange portion; 11…guide hole; 12…optical fiber hole; 13…adhesive filling portion; 131…upper opening; 131A…pressing portion; 132…lower opening; 14…inner wall; 14A…first surface; 14B…second surface; 15…step portion; 15A…guide groove; 17…shield insertion opening; 20…shield; 20A…recessed portion; 21…optical fiber insertion hole; 22…lower portion; 22A…end face; 23…upper portion; 231…protrusion; 231A…end face; 231B…inclined surface; 232…exposed portion; 24…connecting portion; 100…insertion core structure.

Claims

1. A core insert structure, characterized in that: have: A ferrule having a plurality of optical fiber holes arranged side by side in one direction, an adhesive filling portion filled with an adhesive, and a step portion for guiding the optical fiber to the optical fiber holes; and A protective cover is mounted on the ferrule. The protective cover has: An optical fiber insertion hole, configured to correspond to the configuration of the plurality of optical fiber holes, for the plurality of optical fibers to be inserted through; a lower portion, arranged on one side with respect to the optical fiber insertion hole; and The upper portion is arranged on the other side with reference to the optical fiber insertion hole, The upper portion has a protrusion that protrudes further than the end surface of the lower portion in the direction in which the optical fiber is inserted. An upper opening leading to the adhesive filling portion is provided on the upper surface of the ferrule. The end portion of the upper portion on the protruding portion side is exposed from the upper opening in a state in which the end surface of the lower portion is in contact with the end surface of the step portion.

2. The insert structure according to claim 1, characterized in that: The protruding length of the protruding portion is smaller than the length of the step portion in the optical fiber insertion direction.

3. The insert structure according to claim 2, characterized in that: The protrusion has an inclined surface between a surface on the opening side of the adhesive-filled portion and an end surface of the protrusion in the optical fiber insertion direction.

4. The insert structure according to any one of claims 1 to 3, characterized in that: The lower surface of the protrusion is provided on an extension of the upper edge of the optical fiber insertion hole.

5. The insert structure according to any one of claims 1 to 4, characterized in that: An exposing portion is provided to expose the optical fiber inserted into the optical fiber insertion hole.

6. The insert structure according to claim 5, characterized in that: The exposed portion is constituted by recessed portions provided at both ends in the width direction of a region where the plurality of optical fibers are arranged side by side.

7. The insert structure according to claim 5, characterized in that: The exposed portion is constituted by a window provided at a center portion in a width direction where the plurality of optical fibers are arranged side by side.

8. The insert structure according to claim 1, characterized in that: The ferrule has a pressing portion on the wall surface above the adhesive filling portion. The protrusion is arranged on the lower side of the pressing portion when the shield is attached to the ferrule.

9. A method for manufacturing an optical fiber with a ferrule, characterized in that: Carry out the following process: Preparing a ferrule, the ferrule having a plurality of optical fiber holes arranged side by side in one direction, an adhesive filling portion filled with an adhesive, and a step portion for guiding the optical fiber to the optical fiber holes, and an upper opening connected to the adhesive filling portion is provided on the upper surface of the ferrule; preparing a protective cover having optical fiber insertion holes arranged to correspond to the arrangement of the plurality of optical fiber holes and through which the plurality of optical fibers are inserted, a lower portion arranged on one side with the optical fiber insertion holes as a reference, and an upper portion arranged on the other side with the optical fiber insertion holes as a reference and having a protruding portion protruding further than an end surface of the lower portion in an optical fiber insertion direction; The shield is mounted on the ferrule in such a manner that the end surface of the lower portion contacts the end surface of the step portion and the end portion of the upper protrusion portion is exposed from the upper opening, and the protrusion portion is opposed to the step portion inside the adhesive-filled portion; as well as The optical fiber is fixed to the ferrule by filling an adhesive into a gap between an inner wall of the adhesive-filled portion and the protruding portion.

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