Ferrule, optical connector, and method for manufacturing 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] 2. Description of the Related Art 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 cylindrical 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 an 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 for easily manufacturing this 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 side of the ferrule and has elasticity when solidified.

[0006] Patent Document 3 (JP Patent Publication 2001-108867 A) 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 using a mating pin alignment system, 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 part between the left and right guide pin holes is thin-walled symmetrically from top to bottom.

[0008] Patent Document 4 (JP Patent Publication 2001-264585A) discloses a ferrule for an optical connector that is designed to improve the ease of assembly work.

[0009] The ferrule for optical connector described in Patent Document 4 has a guide hole for inserting a guide pin, and has an optical fiber insertion portion 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 correspondence 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] JP 2004-020962 A [Patent Document 2] JP 2007-279576 A [Patent Document 3] JP 2001-108867 A [Patent Document 4] JP 2001-264585 A Summary of the Invention [Problem to be solved by the invention]

[0011] Optical cables have traditionally been used to connect information and communication devices that are far apart, but as information and communication devices become faster and more dense, optical cables are now often used for the internal wiring of information and communication devices.In such cases, the optical connectors that connect the optical cables together are often placed at the ends of the PC boards of the information and communication devices or on the PC boards themselves, making it necessary to miniaturize the optical connectors or the ferrules that make up the optical connectors.

[0012] However, in the pursuit of miniaturization of ferrules in recent years, even if the optical fiber is fixed to the ferrule with an adhesive, the problem of cracks occurring in the optical fiber occurs when the connection end face is roughly polished. Note that rough polishing also includes cutting off a large part of the optical fiber protruding from the ferrule with a cutter or the like. In addition, in order to prevent cracks in the optical fiber, a separate process was required in the manufacturing process. For example, after inserting the optical fiber, it became necessary to reapply adhesive in a post-process. The inventors have found that it is possible to prevent cracks in the optical fiber.

[0013] An object of the present invention is to provide a ferrule that is small and whose manufacturing process can be simplified, 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 equipment, 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 for respectively protruding a plurality of optical fibers provided on one end surface, a plurality of fiber guide holes that are connected to the rear ends of the plurality of optical fiber holes and are parallel to each other, and an optical fiber tape insertion hole for inserting an optical fiber tape of a plurality of optical fibers is provided on the other end surface opposite the one end surface, the ferrule has a flange portion and is provided with an internal space that communicates with the plurality of fiber holes, fiber guide holes and optical fiber tape insertion hole, and is provided with an adhesive filling window on only one surface of the flange portion for filling the internal space with adhesive.

[0015] In recent years, the use of optical fibers for the internal wiring of information and communication devices has been considered, and there is a demand for small ferrules that can connect to optical fibers in small spaces at the connection parts of optical transceivers and connection parts when mounted on a board. As the ferrule becomes smaller, the distance between the splicing end face and the optical fiber tape insertion hole is shortened, and when the distance between the splicing end face and the adhesive filling window is shortened, the distance of the fiber guide hole is shortened. As a result, when an optical fiber is inserted into a ferrule filled with adhesive, the amount of adhesive discharged to the splicing end face is reduced, which causes a problem that cracks are generated 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, the filling window is provided in the flange portion, so that the distance of the fiber guide groove can be secured, and therefore the amount of adhesive discharged to the splicing end face can be secured and the optical fiber can be securely held, and even when the optical fiber is cut and the splicing end face is polished, damage to the optical fiber can be prevented. 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 was formed across the flange, the adhesive leaked near the flange of the ferrule due to capillary action, but by forming the adhesive filling window only on the flange, it was possible to prevent this problem, which made the polishing process difficult.

[0016] (2) In a ferrule according to a second aspect of the present invention, the length of the ferrule from one end face to the other end face may be 4 mm, and the length of the fiber guiding 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 made small to realize high density mounting, and if the guide hole length is not within a predetermined range, the optical fiber may crack during rough polishing. 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 part 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 first aspect 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] Since small, high-density multi-core ferrules require extremely high positional and dimensional accuracy, it is preferable to use polyphenylene sulfide (PPS) resin. The cladding hole diameter of the optical fiber may be 125 micrometers in diameter. It is preferable that the optical fiber hole is larger than the diameter of 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 portion 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 of a small ferrule, the ferrule can be reliably held by the flange, so extremely high precision can be achieved. In particular, the flange of the small ferrule serves as a reference surface when polishing the tip of the optical fiber at a specified angle, for example, 8 degrees, so by forming it around the entire circumference, precision can be improved.

[0022] (5) An optical connector according to another aspect includes a ferrule according to any one of the first to fourth aspects of the present invention, and a plurality of optical fibers loaded into the ferrule.

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

[0024] (6) A manufacturing method for an optical connector according to still another aspect is a manufacturing method for an optical connector using a ferrule according to the first to fourth aspects of the present invention, and includes an adhesive filling step of filling an internal space with adhesive 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 an optical fiber tape insertion hole of the ferrule, an adhesive hardening 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 miniaturized optical connectors in which a plurality of optical fibers are loaded into a ferrule.

[0026] (A) The ferrule may have a ferrule body formed into an approximately rectangular parallelepiped having a flange portion, an optical fiber tape insertion hole provided at the end of the ferrule body on the flange side 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 upper 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, the adhesive filling window being formed in the flange portion and communicating with the guide hole, and the length of the guide hole may be within the range of 1.7 mm or more and 2.5 mm or less. [Brief description of the drawings]

[0027] [Figure 1] FIG. 2 is a schematic perspective view showing an example of a ferrule according to the present embodiment. [Diagram 2] (a) is a schematic top view of the ferrule, (b) is a schematic side view seen from the left side, (c) is a schematic side view seen from the right side, and (d) is a schematic cross-sectional view of the AA plane of (a). [Diagram 3] 1 is a schematic exploded perspective view showing an example of an optical connector composed of a ferrule and an optical fiber tape. [Figure 4] FIG. 2 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 (a). [Diagram 5] FIG. 2 is a diagram showing an example of a rear end face of a ferrule according to an embodiment of the present invention. [Figure 6] FIG. 11 is a plan view showing an example of a comparative example. [Figure 7] FIG. 11 is a plan view showing an example of a comparative example. [Figure 8] FIG. 11 is a plan view showing an example of a comparative example. [Figure 9] FIG. 2 is a diagram showing an example of the observation of the end faces of a ferrule according to an embodiment and an adhesive according to Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 description thereof will not be repeated.

[0029] <First embodiment> (Ferrule 100) Fig. 1 is a schematic perspective view showing an example of a ferrule 100 of this embodiment. Also, Fig. 2(a) is a schematic top view of the ferrule 100, Fig. 2(b) is a schematic side view seen from the left side, Fig. 2(c) is a schematic side view seen from the right side, and Fig. 2(d) is a schematic cross-sectional view of the AA plane of 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 in which a flange is 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 FIG. 2(a)) is the length direction, the direction perpendicular to the length direction (the up-down direction in FIG. 2(a)) is the width direction, and the direction perpendicular to the length direction and the width direction is the up-down direction. Since the ferrule 100 in this embodiment is small and requires particular precision, polishing and the like are performed by utilizing 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, in the ferrule body 10, a plurality of optical fiber holes 20 for inserting, positioning and fixing the removed portion of the optical fiber 101a, a plurality of fiber guiding holes 25 which are parallel to each other and communicate with the rear ends of the plurality of optical fiber holes 20, and a plurality of U-shaped or V-shaped fiber guiding grooves 40 which are parallel to each other and communicate with the rear ends of the plurality of fiber guiding holes 25 are formed 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 passing through it, and an adhesive filling portion 50 for injecting adhesive for fixing 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 in parallel with the plurality of optical fiber holes 20, for inserting guide pins.

[0033] In this embodiment, the optical fiber tape 101 in which a plurality of optical fibers 101a are bundled together is used, as in the conventional case, and the 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 with 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-core. In particular, in recent years, mounting of optical communication wiring on a board has been considered, and there is a demand for compact ferrules 100 that can be connected to optical fibers in a small space at the connection parts of optical transceivers and connection parts when mounted on a board. 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, it is preferable to use polyphenylene sulfide (PPS) resin from the viewpoints of positional accuracy, dimensional accuracy, molding shrinkage rate, and thermal stability. This makes it possible to obtain a ferrule 100 with low connection loss even when compact and highly densely mounted. In addition, for example, granular silica can be used as the inorganic filler, and the strength of the ferrule 100 can be improved by filling it with the inorganic filler.

[0035] (Optical Connector 200) FIG. 3 is a schematic exploded oblique 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 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 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, since the fiber guiding groove 40 can be seen through the adhesive filling window 55 in the adhesive filling part 50, the optical fiber 101a can be easily inserted into the fiber guiding hole 25. In addition, since the length t1 of the fiber guiding hole 25 is 1.7 mm or more, 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 discharged 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 the optical fiber 101a from cracking. This allows the ferrule 100 to be small in size but 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. Furthermore, the length t1 of the fiber guiding 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, thereby making it possible to reduce the overall size of the ferrule 100. In this case, the inner diameter of the fiber guiding 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 preferable 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 fix 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 by utilizing 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, that is, rough polishing and main polishing. The rough polishing also includes the large cutting of the part 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 examples and comparative examples of the ferrule 100. The examples in this embodiment are the ferrule 100 shown in FIGS.

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

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

[0044] [Example] 1 to 3, in the ferrule 100 of the embodiment, 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, and the tip of the optical fiber 101a was visible, and no decrease in working efficiency occurred. Furthermore, the length t1 of the fiber guiding 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 facing 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 for board mounting, so no space is provided for inserting a boot. In this embodiment, the ferrule 100 is created for installation in the connection part of the optical transceiver, so there is no risk of the optical fiber 101a being bent or stressed, and no problem occurs even if a boot is not provided. The presence or absence of a boot insertion hole can be appropriately designed 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 the 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 believed to be because the distance from the rear end face 100b, which faces the front end face 100a as the splicing end face, to the entrance of the fiber guide hole 25 is short, so the amount of overflowing adhesive GL was suppressed by inserting the optical fiber ribbon 101. In this embodiment, 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 makes it possible to prevent the adhesive GL from leaking.

[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 if the excess optical fiber 101a is cut off 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 visually confirmed, there was no space, and therefore work efficiency was reduced. Furthermore, in order to miniaturize 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 comes out to the front end face 100a, and there is no adhesive GL in the portion between the optical fiber 101a and the optical fiber hole 20, and only the adhesive GL adheres to the optical fiber 101a in a bead shape. In this case, even if the adhesive GL is thermally cured, cracks occur in the optical fiber 101a during the rough polishing process. In order 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, and it is necessary to manually apply adhesive to the front end face 100a after inserting the optical fiber, as in the case of the ferrule 100 of the embodiment shown in FIG. 9 after changing the shape. As a result, the number of work steps increases, and production efficiency is significantly reduced.

[0048] [Comparative Example 2] As shown in FIG. 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 the adhesive filling portion 50 were provided 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 thoroughly, and further, although the tip of the optical fiber 101a could be visually confirmed, there was not enough space, which reduced the 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, resulting in a state in which the step between the ferrule body 10 and the flange portion 30 could not be grasped during the polishing process.

[0050] [Comparative Example 3] As shown in FIG. 8, in a ferrule 930 of Comparative Example 3, adhesive filling window 55 and adhesive filling portion 50 were formed across ferrule body 10 and 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 step between the ferrule body 10 and the flange portion 30 during the polishing process.

[0051] [Considerations of Examples and Comparative Examples] When comparing the Example with Comparative Examples 1, 2 and 3, the Example is a) The adhesive filling window 55 is long. b) An adhesive filling window 55 is provided only in the flange portion 30. c) The length t1 of the fiber guiding hole 25 is 1.7 mm or more. Therefore, the reason why the ferrule 100 of the embodiment has good workability and does not cause cracks in the optical fiber 101a is believed 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 realize a compact ferrule 100 with a length t3 of 4 mm, the flange 30 should be provided with the adhesive filling portion 50 and the 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 is preferably 1.7 mm or more. In addition, since the ferrule 100 does not have a boot, it cannot withstand the vertical and lateral stresses that are applied to the optical fiber 101a of several tens of meters or more. Therefore, it is considered to be optimal for short-distance communication such as internal communication in personal computers, communication on a circuit board, and communication in wireless communication devices.

[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 "the 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 is as described above, the present invention is not limited thereto. It is 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 hole 25 Fiber guide hole 30 Flange 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 optical 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 arranged so that an optical fiber tape having a boot cannot be inserted, but an optical fiber tape having a boot that does not have a boot can be inserted, and the ferrule has an internal space that connects the multiple fiber holes, the fiber guide hole, and the optical fiber tape insertion hole, and is also equipped with an adhesive filling window for filling the internal space with adhesive.

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. The fiber guide hole is provided with adhesive that is dispensed onto the one end surface when the optical fiber is inserted after being filled with adhesive through the adhesive filling window; or a length capable of storing an amount of adhesive required to dispense onto the one end surface in a manner that will not cause cracks in the optical fiber during the polishing process of the one end surface; 2. The ferrule according to claim 1, wherein the total length of the optical fiber hole and the fiber guide hole is longer than the length from the one end face to the end of the flange portion on the one end face side.

4. the ferrule is made of PPS resin, The length from the one end face to the other end face of the ferrule is 4 mm, a length of the fiber guide hole in the internal space of the ferrule being 1.7 mm or more and 2.5 mm or less; 3. The ferrule of claim 1, wherein the optical fiber hole has a diameter of 125 micrometers.

5. An optical connector comprising the ferrule according to claim 1 and a plurality of the optical fibers loaded therein.

6. A method for manufacturing an optical connector using the ferrule according to any one of claims 1 to 4, 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.

7. A ferrule having a plurality of optical fiber holes provided on one end face for respectively projecting a plurality of optical fibers, a plurality of fiber guide holes communicating with the rear ends of the plurality of optical fiber holes and parallel to each other, and an optical fiber tape insertion hole for inserting the optical fiber tapes of the plurality of optical fibers provided on the other end face opposite to the one end face, 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.

8. A ferrule as described in claim 7, wherein the distance from the other end face to the fiber guide hole is 3.0 mm or less.

9. A ferrule as described in claim 7 or 8, wherein the optical fiber tape insertion hole has a flat bottom and does not have a boot insertion hole.

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