Ferrule, optical connector, and method of manufacturing the optical connector

Abstract

To provide a ferrule that is small and capable of simplifying a manufacturing process, and an optical connector and a method for manufacturing the optical connector.SOLUTION: A ferrule 100 has a plurality of fiber holes 20 for projecting each of a plurality of optical fibers 101a provided on a front end face 100a, a plurality of fiber guide holes 25 communicating with rear ends of the plurality of optical fiber holes 20 and being parallel to each other, and an optical fiber tape insertion hole 35 for inserting an optical fiber tape 101 of the plurality of optical fibers 101a provided on a rear end face 100b at an opposite side to the one front end face. The ferrule 100 has a flange part 30, and not only includes an internal space communicating the plurality of fiber holes 20, fiber guide holes 25, and the optical fiber tape insertion hole 35, but also includes an adhesive filling window 55 for filling the internal space with an adhesive GL on only one surface of the flange part 35.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a ferrule that optically connects optical fibers of an optical cable that transmits optical signals, an optical connector that holds the optical fibers, and a method for manufacturing the optical connector. [Background technology]

[0002] Optical fiber cables using optical fibers are capable of transmitting large amounts of information at high speeds, and are therefore widely used for information communication in both domestic and industrial applications. For example, Patent Document 1 (JP 2004-020962 A) discloses an optical connector that, when fixing an optical fiber tape to the ferrule of the optical connector, can pour adhesive resin evenly into the optical fiber tape insertion hole of the ferrule without generating air bubbles.

[0003] The optical connector described in Patent Document 1 comprises a tubular boot for protecting an optical fiber tape covering multiple optical fibers, and a ferrule having a boot insertion hole for attaching the boot, an optical fiber tape insertion hole communicating with the boot insertion hole, and multiple optical fiber holes for multiple optical fibers communicating with the optical fiber tape insertion hole.The optical connector is formed by inserting multiple optical fibers into the optical fiber holes and inserting the boot with the optical fiber tape inserted into the boot insertion hole, and filling adhesive resin through a window hole provided at the top of the optical fiber tape insertion hole, and a sloped portion is provided in the optical fiber tape storage portion of the fiber tape insertion hole.

[0004] Patent Document 2 (JP 2007-279576 A) discloses an optical connector that can reduce the bending force of an optical fiber by using a boot that has sufficient flexibility while preventing leakage of adhesive, and a manufacturing method that can easily manufacture such an optical connector.

[0005] The optical connector described in Patent Document 2 is an optical connector in which an optical fiber is inserted into a fiber insertion hole of a ferrule and fixed with an adhesive, and is characterized by having a resin material portion that is injected in a liquid state into the rear end of the ferrule and has elasticity when solidified.

[0006] Patent Document 3 (Japanese Patent Laid-Open Publication No. 2001-108867) discloses a ferrule for an MT optical connector that has high precision and shape stability.

[0007] The ferrule described in Patent Document 3 is a ferrule for a multi-core optical connector made of plastic and employing a mating pin alignment method, with guide pin holes formed on both the left and right sides of multiple horizontally arranged optical fiber holes, and is characterized by the fact that the middle section between the left and right guide pin holes is thin-walled and symmetrical from top to bottom.

[0008] Patent Document 4 (Japanese Patent Laid-Open Publication No. 2001-264585) discloses a ferrule for an optical connector that is designed to improve the ease of assembly work.

[0009] The ferrule for optical connectors described in Patent Document 4 has guide holes for inserting guide pins and an optical fiber insertion section extending inward from an optical connection port formed on the front end face side, and is characterized in that convex portions are formed on the front end face side in accordance with the number of optical connection ports, and the optical connection ports are located at the tops of the convex portions. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-020962 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-279576 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-108867 [Patent Document 4] Japanese Patent Application Laid-Open No. 2001-264585 Summary of the Invention [Problem to be solved by the invention]

[0011] Optical cables have traditionally been used to connect information and communication devices over long distances, but as information and communication devices have become faster and denser, optical cables are now often used for internal wiring in information and communication devices.In such cases, the optical connectors that connect optical cables together are often placed at the end of the PC board of the information and communication device or on the PC board itself, which has created a need to miniaturize the optical connectors or the ferrules that make up the optical connectors.

[0012] However, with the recent trend toward smaller ferrules, even if an optical fiber is fixed to the ferrule with adhesive, the problem of cracks occurring in the optical fiber occurs when the connection end face is roughly polished. Note that rough polishing also involves cutting off a large portion of the optical fiber protruding from the ferrule with a cutter or the like. Furthermore, in order to prevent cracks in the optical fiber, additional manufacturing processes were required. For example, after inserting the optical fiber, it became necessary to reapply adhesive in a subsequent process. The inventors have discovered that cracks in the optical fiber can be prevented.

[0013] An object of the present invention is to provide a small ferrule that can be manufactured using a simplified manufacturing process, an optical connector, and a method for manufacturing the optical connector. Another object of the present invention is to provide a ferrule, an optical connector, and a method for manufacturing an optical connector, which is a small ferrule that can accommodate the increasing density of information devices, and which can reliably hold an optical fiber while preventing defects such as cracks and simplifying the manufacturing process. [Means for solving the problem]

[0014] (1) A ferrule according to one aspect has a plurality of fiber holes formed on one end surface for respectively projecting a plurality of optical fibers, a plurality of fiber guide holes formed in communication with the rear ends of the plurality of optical fiber holes and parallel to one another, and an optical fiber tape insertion hole formed on the other end surface opposite the one end surface for inserting an optical fiber tape of a plurality of optical fibers, the ferrule having a flange portion and an internal space communicating with the plurality of fiber holes, fiber guide holes and optical fiber tape insertion hole, and an adhesive filling window formed on only one surface of the flange portion for filling the internal space with adhesive.

[0015] In recent years, the use of optical fiber cables for internal wiring in information and communication devices has been considered, and compact ferrules that can connect to optical fibers in small spaces are required for the connection parts of optical transceivers and connection parts in board mounting. As ferrules become smaller, the distance between the splicing end face and the optical fiber tape insertion hole is shortened, and as a result, the distance between the splicing end face and the adhesive filling window is shortened, which in turn shortens the distance of the fiber guide hole. As a result, when an optical fiber is inserted into a ferrule filled with adhesive, the amount of adhesive dispensed onto the splicing end face is reduced, which causes the problem of cracks occurring in the optical fiber during the process of cutting the optical fiber and polishing the splicing end face. In the ferrule of the present invention, by providing a filling window in the flange portion, the distance of the fiber guide groove can be ensured, so the amount of adhesive dispensed onto the splicing end face is ensured, allowing the optical fiber to be securely held. This prevents damage to the optical fiber even when the optical fiber is cut and the splicing end face is polished. That is, by forming an adhesive filling window in the flange of the ferrule, it is possible to ensure that the length of the fiber guide hole for the optical fiber is at least a predetermined distance in the internal space of the ferrule. Furthermore, when an adhesive filling window is formed across the flange, the adhesive leaks and flows near the flange of the ferrule due to capillary action, but by forming the adhesive filling window only on the flange, it is possible to prevent this problem, which makes the polishing process difficult.

[0016] (2) In a ferrule according to one aspect of the second invention, the length from one end face to the other end face of the ferrule may be 4 mm, and the length of the fiber guide hole in the internal space of the ferrule may be 1.7 mm or more and 2.5 mm or less.

[0017] In this case, the ferrule is miniaturized to achieve high-density mounting, and if the guide hole length is not within a predetermined range, the problem of cracks occurring in the optical fiber during rough polishing occurs. Therefore, the length of the fiber guide hole is preferably 1.7 mm or more and 2.5 mm or less. The length from one end face to the other end face is preferably 6.0 mm or less, more preferably 5.0 mm or less, and even more preferably 4.0 mm or less. Here, the direction connecting the front end face and the rear end face is defined as the length direction, the direction perpendicular to the length direction is defined as the width direction, and the direction perpendicular to the length direction and the width direction is defined as the up-down direction. Note that rough polishing also includes largely cutting off the portion of the optical fiber protruding from the ferrule with a cutter or the like.

[0018] (3) A ferrule according to a third aspect of the present invention is the ferrule according to the second aspect of the present invention, wherein the ferrule is made of PPS resin, and the optical fiber hole may have a diameter of 125 micrometers.

[0019] Because small, high-density multi-fiber ferrules require extremely high positional and dimensional accuracy, polyphenylene sulfide (PPS) resin is preferably used. The cladding hole diameter of the optical fiber may be 125 micrometers. It is preferable that the optical fiber hole diameter be larger than 125 micrometers by +1 micrometer or less.

[0020] (4) A ferrule according to a fourth aspect of the present invention is the ferrule according to the third aspect of the present invention, wherein the flange of the ferrule is preferably formed over the entire circumference in parallel with one end face of the ferrule.

[0021] In this case, when performing a polishing process on a small ferrule, the ferrule can be reliably held by the flange, thereby achieving extremely high precision. In particular, the flange of the miniaturized ferrule serves as a reference surface when polishing the tip of the optical fiber at a predetermined angle, for example, 8 degrees, so forming it around the entire circumference can improve precision.

[0022] (5) An optical connector according to another aspect is configured by loading a plurality of optical fibers into the ferrule according to any one of the first to fourth aspects of the present invention.

[0023] In this case, it is possible to easily mass-produce a miniaturized optical connector in which a plurality of optical fibers are loaded into a ferrule.

[0024] (6) A manufacturing method for an optical connector according to yet another aspect is a manufacturing method for an optical connector using a ferrule according to any one of the first to fourth aspects of the present invention, and includes an adhesive filling step of filling adhesive into the internal space through an adhesive filling window provided in the flange portion of the ferrule, an optical fiber tape insertion step of inserting an optical fiber through the optical fiber tape insertion hole of the ferrule, an adhesive curing step of fixing the optical fiber, and a polishing step of polishing a plurality of optical fibers protruding from one end face of the ferrule.

[0025] In this case, it is possible to easily mass-produce a miniaturized optical connector in which a plurality of optical fibers are loaded into a ferrule.

[0026] (A) The ferrule may also have a ferrule body formed into an approximately rectangular parallelepiped and having a flange portion, an optical fiber tape insertion hole provided at the flange-side end of the ferrule body for inserting an optical fiber tape, an optical fiber hole provided on the connection end face side of the other end of the ferrule body, a fiber guide hole provided between the optical fiber tape insertion hole and the optical fiber hole, and an adhesive filling window formed on the top surface of the ferrule body for filling the internal space of the ferrule body with adhesive for fixing the optical fiber to the ferrule body, wherein the adhesive filling window is formed in the flange portion and communicates with the guide hole, and the length of the guide hole may be within a range of 1.7 mm to 2.5 mm. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 2 is a schematic perspective view showing an example of a ferrule according to the present embodiment. [Figure 2] (a) is a schematic top view of the ferrule, (b) is a schematic side view seen from the left, (c) is a schematic side view seen from the right, and (d) is a schematic cross-sectional view of the AA plane of (a). [Figure 3] 1 is a schematic exploded perspective view showing an example of an optical connector composed of a ferrule and an optical fiber ribbon. [Figure 4] FIG. 10 is a schematic cross-sectional view showing an example of an optical connector into which an optical fiber ribbon has been inserted, cut along a plane corresponding to the AA plane in FIG. [Figure 5] FIG. 2 is a diagram showing an example of a rear end face of a ferrule according to an embodiment. [Figure 6] FIG. 10 is a plan view showing an example of a comparative example. [Figure 7] FIG. 10 is a plan view showing an example of a comparative example. [Figure 8] FIG. 10 is a plan view showing an example of a comparative example. [Figure 9] FIG. 1 is a diagram showing an example of the observation of the end faces of the ferrule of the example and the adhesive of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals, and their names and functions are also the same, so detailed descriptions thereof will not be repeated.

[0029] First Embodiment (Ferrule 100) Fig. 1 is a schematic perspective view showing an example of a ferrule 100 according to this embodiment. Fig. 2(a) is a schematic top view of the ferrule 100, Fig. 2(b) is a schematic side view as seen from the left side, Fig. 2(c) is a schematic side view as seen from the right side, and Fig. 2(d) is a schematic cross-sectional view of the AA plane in Fig. 2(a).

[0030] As shown in FIGS. 1 and 2, a ferrule 100 of this embodiment comprises a ferrule body 10 and a flange portion 30 formed on the ferrule body 10 . In the following description of this specification, the direction connecting the front end face 100a and the rear end face 100b (the left-right direction in Figure 2(a)) is referred to as the length direction, the direction perpendicular to the length direction (the up-down direction in Figure 2(a)) is referred to as the width direction, and the direction perpendicular to the length direction and the width direction is referred to as the up-down direction. Since the ferrule 100 in this embodiment is small and requires particular precision, polishing and the like are performed using the steps formed on the four surfaces between the ferrule body 10 and the flange portion 30, i.e., other than the front end face 100a and the rear end face 100b.

[0031] In addition, the ferrule body 10 is formed with a plurality of optical fiber holes 20 for inserting, positioning, and fixing the removed portion of the optical fiber 101a, a plurality of fiber guide holes 25 that are connected to the rear ends of the plurality of optical fiber holes 20 and are parallel to each other, and a plurality of U-shaped or V-shaped fiber guide grooves 40 that are connected to the rear ends of the plurality of fiber guide holes 25 and are parallel to each other, from the front end face 100a to the rear end face 100b of the ferrule body 10.

[0032] The flange portion 30 of the ferrule 100 is provided with an optical fiber tape insertion hole 35 for inserting an optical fiber tape 101 having an optical fiber 101a inserted therethrough, and an adhesive filling portion 50 for injecting adhesive to fix the optical fiber 101a to the ferrule body 10. The ferrule 100 is formed with two guide pin holes 60 in the vicinity of both ends in the width direction, parallel to the plurality of optical fiber holes 20, for inserting guide pins.

[0033] In this embodiment, an optical fiber tape 101 in which a plurality of optical fibers 101a are bundled together is used, as is the case with conventional optical fiber tape 101, and an optical fiber tape 101 further provided with a boot is not used. Therefore, a smaller optical fiber tape insertion hole 35, which is not large enough to insert a boot, is formed in the rear end face 100b of the ferrule 100. As shown in the AA cross section of Fig. 2, the ferrule 100 is provided with an internal space that communicates between the optical fiber holes 20 and the fiber guide holes 25 and the optical fiber tape insertion hole 35, and an adhesive filling portion 50 that communicates with the internal space.

[0034] To accommodate the increasing density of information devices, the ferrules 100 are becoming thinner and more multi-fibered. In particular, in recent years, the mounting of optical communication wiring on a board has been considered, and a compact ferrule 100 that can be connected to an optical fiber in a narrow space is required for the connection part of an optical transceiver and the connection part for board mounting. In the ferrule 100 of this embodiment, the number of optical fibers 101a is 12, the diameter is 1.25 mm, the maximum width of the ferrule 100 is 7.00 mm, and the length t3 of the ferrule 100 is 4 mm. Therefore, the ratio of the width to the height is 5.6. The ferrule 100 in this embodiment is formed, for example, by molding a resin material filled with an inorganic filler. The resin material is a thermosetting epoxy resin, PPS (polyphenylene sulfide), or the like. Among these, polyphenylene sulfide (PPS) resin is preferably used from the viewpoints of positional accuracy, dimensional accuracy, molding shrinkage rate, and thermal stability. This allows the ferrule 100 to be small and have low connection loss even when mounted at high density. Furthermore, granular silica, for example, can be used as the inorganic filler, and filling the ferrule 100 with the inorganic filler can improve the strength of the ferrule 100.

[0035] (Optical Connector 200) FIG. 3 is a schematic exploded perspective view showing an example of an optical connector 200 composed of a ferrule 100 and an optical fiber tape 101, and FIG. 4 is a schematic cross-sectional view showing an example of the optical connector 200 with the optical fiber tape 101 inserted, cut along a plane corresponding to the AA plane in FIG. 2(a).

[0036] First, adhesive is filled into the adhesive filling portion 50 provided in the flange portion 30. The adhesive is preferably a thermosetting epoxy adhesive. However, any other curing adhesive such as a UV curing adhesive may also be used. Next, the optical fiber tape 101 in which the plurality of optical fibers 101 a are bundled is inserted into the optical fiber tape insertion hole 35 provided in the flange portion 30 of the ferrule 100 .

[0037] 3, the tip end side of the optical fiber ribbon 101 is an optical fiber 101a from which the coating of the optical fiber ribbon 101 has been stripped. The optical fiber 101a is inserted into the internal space of the ferrule 100 so as to pass through the fiber guiding groove 40, the fiber guiding hole 25, and the optical fiber hole 20 and reach the front end face 100a of the ferrule 100.

[0038] In this case, the fiber guide groove 40 can be seen through the adhesive filling window 55 in the adhesive filling section 50, so the optical fiber 101a can be easily inserted into the fiber guide hole 25. Furthermore, the length t1 of the fiber guide hole 25 is 1.7 mm or more, so the optical fiber 101a can be securely held. That is, because the length t1 of the guide hole is equal to or greater than a predetermined distance, when the optical fiber 101a is inserted into the ferrule 100 filled with adhesive, a sufficient amount of adhesive is dispensed onto the connection end face of the ferrule 100 (see FIG. 9). Therefore, even when the optical fiber 101a is subsequently cut and the connection end face is polished, the optical fiber 101a can be securely held, preventing cracks from occurring in the optical fiber 101a. This allows the ferrule 100 to be made compact and with low connection loss. The length t1 of the fiber guide hole 25 is preferably 1.0 mm or more, more preferably 1.5 mm or more, and even more preferably 1.7 mm or more, so that the optical fiber 101a can be reliably held by the adhesive GL. The length t1 of the fiber guide hole 25 is preferably 3.0 mm or less, more preferably 2.5 mm or less, and even more preferably 2.0 mm or less, which allows the overall size of the ferrule 100 to be made smaller. In this case, the inner diameter of the fiber guide hole 25 can be appropriately selected depending on the cladding diameter of the optical fiber 101a, and can be, for example, 250 μm, 125 μm, 100 μm, 80 μm, or 50 μm.

[0039] The optical fiber 101a is inserted so as to protrude about 1 mm from the front end face 100a of the ferrule 100. It is desirable to make the adhesive GL penetrate into the fiber guide hole 25 and the optical fiber hole 20 by moving the optical fiber 101a back and forth.

[0040] Next, the adhesive GL is thermally cured to set the adhesive. After that, the optical fiber 101a protruding largely from the front end face 100a is cut with a cutter or the like, and the front end face 100a of the ferrule 100 to which the optical fiber tape 101 is fixed is polished using the steps of the ferrule body 10 and the flange portion 30, thereby forming the optical connector 200. In this embodiment, the polishing is performed in two steps: rough polishing and main polishing. The rough polishing also includes the step of largely cutting the portion of the optical fiber protruding from the ferrule with a cutter or the like.

[0041] (Examples and Comparative Examples of Ferrule 100) The following describes an example and a comparative example of the ferrule 100. The example in this embodiment is the ferrule 100 shown in FIGS.

[0042] FIG. 5 is a diagram showing an example of the rear end face 100b of the ferrule 100 of the embodiment, FIG. 6 is a plan view showing an example of the ferrule 910 of the comparative example 1, FIG. 7 is a plan view showing an example of the ferrule 920 of the comparative example 2, and FIG. 8 is a plan view showing an example of the ferrule 930 of the comparative example 3.

[0043] 9 is a diagram showing an example of observed end faces of adhesives for the ferrule 100 of the example and the ferrule 910 of comparative example 1. The ferrule 910 of comparative example 1 is shown before the shape change, and the ferrule 100 of the example is shown after the shape change. The end photograph shows the front end face 100a, and the plan photograph shows the state as viewed from above.

[0044] [Example] 1 to 3, in the ferrule 100 of the example, an adhesive filling window 55 and an adhesive filling portion 50 were provided in the flange portion 30. In this case, the length of the adhesive filling window 55 was 1.20 mm, which allowed the tip of the optical fiber 101a to be visually confirmed, and no decrease in work efficiency occurred. Furthermore, the length t1 of the fiber guide hole 25 could be set to 1.7 mm while realizing the miniaturization of the ferrule 100 itself. As a result, no cracks occurred in the optical fiber 101a.

[0045] The ferrule 100 of this embodiment does not have a boot insertion hole for inserting a boot on the rear end face 100b side, which is opposite the front end face 100a, which is the connection end face. This is because a small ferrule 100 is required for the connection part of the optical transceiver and the connection part when mounted on a board, so no space for inserting a boot is provided. In this embodiment, the ferrule 100 is created to be installed in the connection part of the optical transceiver, so there is no risk of the optical fiber 101a being bent or subjected to stress, and no problems arise even if a boot is not provided. The presence or absence of a boot insertion hole can be designed as appropriate depending on the purpose of the ferrule 100 to be used. Furthermore, as shown in FIG. 5, even when the optical fiber ribbon 101 was assembled without using a boot, there was no leakage of adhesive GL, and the adhesive GL did not overflow from the optical fiber ribbon insertion hole 35 into the guide pin hole 60. This is thought to be because the distance from the rear end face 100b, which faces the front end face 100a (the splicing end face), to the entrance of the fiber guide hole 25 was short, so the amount of adhesive GL that overflowed when the optical fiber ribbon 101 was inserted was suppressed. In this example, this distance was set to 1.8 mm, but it is preferably 3.0 mm or less, more preferably 2.5 mm or less, and even more preferably 2.0 mm or less. This prevents leakage of adhesive GL.

[0046] 9, in the ferrule 100 of the embodiment, the adhesive GL overflows firmly onto the front end face 100a, and it can be seen that the adhesive GL is formed in a convex shape at the portion between the optical fiber 101a and the optical fiber hole 20. In this case, by thermally curing the adhesive GL, even when the excess optical fiber 101a is cut with a blade such as a cutter, no cracks are generated in the optical fiber 101a.

[0047] [Comparative Example 1] As shown in FIG. 6, in the ferrule 910 of Comparative Example 1, the adhesive filling window 55 and the adhesive filling portion 50 were provided on the ferrule body 10 side, as in the conventional ferrule. In this case, the length of adhesive filling window 55 was 0.8 mm, making it difficult to insert optical fiber 101a. That is, although the tip of optical fiber 101a could be seen, there was not enough space, which reduced work efficiency. Furthermore, due to the miniaturization of the ferrule itself, the length of the fiber guide hole 25 could only be 0.5 mm. Therefore, as shown in FIG. 9, in the ferrule 910 of Comparative Example 1, not much adhesive GL is present on the front end face 100a, and there is no adhesive GL between the optical fiber 101a and the optical fiber hole 20. Instead, only beads of adhesive GL adhere to the optical fiber 101a. In this case, even if the adhesive GL is thermally cured, cracks occur in the optical fiber 101a during the rough polishing process. To prevent these cracks, it is necessary to increase the amount of adhesive that seeps out toward the front end face 100a when the optical fiber 101a is inserted. Therefore, after inserting the optical fiber, it is necessary to manually apply adhesive to the front end face 100a, as in the case of the ferrule 100 of the embodiment shown in FIG. 9 after the shape change. As a result, the number of work steps increases, and production efficiency is significantly reduced.

[0048] Comparative Example 2 As shown in Figure 7, in the ferrule 920 of Comparative Example 2, in order to change the length of the fiber guiding hole 25 to be longer than 0.5 mm, the adhesive filling window 55 and adhesive filling portion 50 were arranged closer to the flange portion 30 side of the ferrule body 10.

[0049] In this case, the length of the fiber guide hole 25 was increased to 1.5 mm. However, because the length of the adhesive filling window 55 was set to 0.5 mm, the adhesive could not be filled properly, and furthermore, although the tip of the optical fiber 101a could be seen, there was not enough space, which reduced work efficiency. Furthermore, during the heating process of heating the adhesive, capillary action occurred, causing the adhesive to flow between the ferrule body 10 and the flange portion 30, making it impossible to grasp the steps between the ferrule body 10 and the flange portion 30 during the polishing process.

[0050] Comparative Example 3 As shown in FIG. 8, in a ferrule 930 of Comparative Example 3, an adhesive filling window 55 and an adhesive filling portion 50 were formed across the ferrule body 10 and the flange portion 30. In this case, the length of the adhesive filling window 55 could be reliably set, but during the heating process of heating the adhesive, capillary action occurred, causing the adhesive to flow between the ferrule body 10 and the flange portion 30, making it impossible to grip the steps of the ferrule body 10 and the flange portion 30 during the polishing process.

[0051] [Considerations of Examples and Comparative Examples] When comparing the Examples with Comparative Examples 1, 2 and 3, the Examples are: a) The adhesive filling window 55 has a large length. b) Only the flange portion 30 is provided with an adhesive filling window 55. c) The length t1 of the fiber guide hole 25 is 1.7 mm or more. Therefore, the reason why the ferrule 100 of the embodiment has good work efficiency and does not cause cracks in the optical fiber 101a is thought to be that the adhesive filling window 55 is formed only in the flange portion 30 and the length t1 of the fiber guide hole 25 is 1.7 mm or more.

[0052] From the above results, it was found that in the ferrule 100, in order to achieve a compact length t3 of 4 mm, the flange 30 should be provided with the adhesive filling portion 50 and adhesive filling window 55, and the fiber guiding hole 25 should be formed to a predetermined length. It was also found that the length t1 of the fiber guiding hole 25 should preferably be 1.7 mm or more. Since the ferrule 100 does not have a boot, it cannot withstand the vertical and lateral stresses that are applied when an optical fiber 101a is several tens of meters or longer. Therefore, it is considered to be optimal for short-distance communication such as internal communication in a personal computer, communication on a circuit board, and communication in a wireless communication device.

[0053] In the present invention, the multiple optical fibers 101a correspond to "multiple optical fibers," the optical fiber hole 20 corresponds to "multiple fiber holes," the front end face 100a corresponds to "one end face," the fiber guide hole 25 corresponds to "multiple fiber guide holes," the optical fiber tape 101 corresponds to "optical fiber tape," the optical fiber tape insertion hole 35 corresponds to "optical fiber tape insertion hole," the rear end face 100b corresponds to "other end face," the ferrule 100 corresponds to "ferrule," the flange portion 30 corresponds to "flange portion," the adhesive GL corresponds to "adhesive," the adhesive filling window 55 corresponds to "adhesive filling window," and the optical connector 200 corresponds to "optical connector."

[0054] Although a preferred embodiment of the present invention has been described above, the present invention is not limited thereto. It will be understood that various other embodiments can be made without departing from the spirit and scope of the present invention. Furthermore, although the actions and effects of the configuration of the present invention are described in this embodiment, these actions and effects are merely examples and do not limit the present invention. [Explanation of symbols]

[0055] 10 Ferrule body 20 optical fiber holes 25 Fiber guide hole 30 Tsuba 35 Optical fiber tape insertion hole 50 Adhesive filling section 55 Adhesive-filled window 100 ferrules 100a Front end surface 100b Rear end surface 101 Optical Fiber Tape 101a optical fiber 200 Optical Connector GL Adhesive

Claims

1. a ferrule having a first end surface provided with a plurality of fiber holes for respectively projecting a plurality of optical fibers, a plurality of fiber guide holes communicating with rear ends of the plurality of fiber holes and parallel to one another, and an optical fiber tape insertion hole for inserting an optical fiber tape of the plurality of optical fibers provided in another end surface opposite to the first end surface, the optical fiber tape insertion hole is provided so as not to allow insertion of an optical fiber tape having a boot and grouping the optical fibers together, but is provided so as to allow insertion of an optical fiber tape having a boot and grouping the optical fibers together, the optical fiber tape insertion hole is provided with an internal space communicating with the plurality of fiber holes, the fiber guide hole and the optical fiber tape insertion hole, and an adhesive filling window for filling an adhesive into the internal space is provided only in the flange portion, The length of the ferrule is 4 mm or less, the adhesive-filled window has a length of 1.2 mm or more; The fiber guiding hole has a length t1 of 1.7 mm or more.

2. a plurality of U-shaped or V-shaped fiber guide grooves, which are part of the fiber guide hole, are provided so as to be visible from the adhesive filling window; 2. The ferrule according to claim 1, wherein the fiber guide hole extends from the vicinity of the one end face to the flange portion, has a predetermined length capable of holding the optical fiber, and allows the plurality of optical fibers to be smoothly inserted into the fiber hole.

3. 3. An optical connector comprising the ferrule according to claim 1 or 2, and a plurality of the optical fibers loaded therein.

4. A method for manufacturing an optical connector using the ferrule according to any one of claims 1 to 3, comprising the steps of: an adhesive filling step of filling the adhesive into the internal space through the adhesive filling window of the ferrule; an optical fiber tape insertion step of inserting an optical fiber tape having a plurality of optical fibers without a boot into the optical fiber tape insertion hole of the ferrule; a step of curing an adhesive for fixing the optical fiber; a polishing step of polishing the plurality of optical fibers protruding from one end face of the ferrule.

5. a ferrule having a first end surface provided with a plurality of fiber holes for respectively projecting a plurality of optical fibers, a plurality of fiber guide holes communicating with rear ends of the plurality of fiber holes and parallel to one another, and an optical fiber tape insertion hole for inserting an optical fiber tape of the plurality of optical fibers provided in another end surface opposite to the first end surface, the ferrule has a flange portion, and an internal space communicating with the plurality of fiber holes, the fiber guide hole, and the optical fiber tape insertion hole, and an adhesive filling window for filling an adhesive into the internal space is provided on only one surface of the flange portion; The length of the ferrule is 4 mm or less, the adhesive-filled window has a length of 1.2 mm or more; The fiber guiding hole has a length t1 of 1.7 mm or more.

6. 6. The ferrule according to claim 5, wherein the distance from the other end face to the fiber guide hole is 3.0 mm or less.

7. 7. The ferrule according to claim 5, wherein the optical fiber tape insertion hole has a flat bottom and does not have a boot insertion hole.

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