Ferrule, optical connector, and optical connection structure

Abstract

A ferrule (10) comprising: an optical fiber holding section (11c) configured so as to hold a plurality of optical fibers (3); and a first-side surface (13) and a second-side surface (14) that are mutually facing in a second direction that intersects a first direction in which an optical fiber holding section (11c) extends. A first recessed section (15) or a first protruding section (115) that extend along the first direction are provided in the first-side surface (13). A second recessed section (16) or a second protruding section (116) that extend along the first direction are provided in the second-side surface (14). In this ferrule (10), the first recessed section (15) or the first protruding section (115) have a first positioning section (15a) and a second positioning section (15b) that are mutually separated in the first direction.

Description

[Technical Field]

[0001] The present disclosure relates to a ferrule, an optical connector, and an optical connection structure. This application claims priority from Japanese Application No. 2020-161212, filed on September 25, 2020, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Patent Document 1 discloses a technique for aligning multi-core optical fibers using guide pins. In this technique, one end of a pair of guide pins is inserted into a pair of guide pin insertion holes provided in the tip surface of a ferrule, and the other end of the pair of guide pins is inserted into a pair of guide pin insertion holes provided in the tip surface of a mating ferrule. This allows the alignment of the multi-core optical fibers (i.e., the alignment of the multi-core optical fiber with the mating multi-core optical fiber) to be achieved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-90974 Summary of the Invention

[0004] The present disclosure provides, as one aspect, a ferrule. The ferrule includes an optical fiber holding part configured to hold a plurality of optical fibers, and a first side surface and a second side surface facing each other in a second direction intersecting a first direction in which the optical fiber holding part extends. The first side surface is provided with a first recess or a first protrusion extending along the first direction. The second side surface is provided with a second recess or a second protrusion extending along the first direction. The first recess or the first protrusion has a first positioning part and a second positioning part that are spaced apart from each other in the first direction.

[0005] Another aspect of the present disclosure provides an optical connector, which includes the above-described ferrule and a plurality of optical fibers held in an optical fiber holding portion.

[0006] In yet another aspect, the present disclosure provides an optical connection structure. This optical connection structure includes a plurality of optical fibers, a ferrule that holds the plurality of optical fibers, and an adapter. The adapter is cylindrical and configured so that the ferrule is inserted into and fitted with another ferrule to be connected, with the ferrule facing each other inside the cylindrical shape. The ferrule has a first side surface and a second side surface that face each other in a second direction that intersects with a first direction in which the ferrule is inserted into the adapter. The first side surface is provided with a first recess or a first protrusion that extends along the first direction. The second side surface is provided with a second recess or a second protrusion that extends along the first direction. The inner surface of the adapter is provided with a third protrusion that can be fitted with the first recess or the third recess that can be fitted with the first protrusion, and a fourth protrusion that can be fitted with the second recess or the fourth recess that can be fitted with the second protrusion. In this optical connection structure, the first recess or first convex portion has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and the second recess or second convex portion has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction, or the third convex portion or third recess has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and the fourth convex portion or fourth recess has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a state in which an optical connector is attached to an adapter in an optical connection structure according to one embodiment. [Figure 2] FIG. 2 is a perspective view showing a state in which the optical connector is detached from the adapter in the optical connection structure shown in FIG. [Figure 3] FIG. 3 is a perspective view showing an optical connector according to one embodiment. [Figure 4]FIG. 4 is a perspective view showing a ferrule of the optical connector shown in FIG. [Figure 5] FIG. 5 is a perspective view showing a state in which the ferrule (optical connector) shown in FIG. 4 is connected to another ferrule (optical connector) in an adapter according to a modified example. [Figure 6] FIG. 6 is a side view of the connection state shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view of the connected state shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view of an optical connection structure according to a modified example. [Figure 9] FIG. 9 is a cross-sectional view of an optical connection structure according to another modified example. [Figure 10] FIG. 10 is a cross-sectional view of an optical connection structure according to yet another modified example. [Figure 11] FIG. 11 is a cross-sectional view of an optical connection structure according to yet another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Problem to be solved by this disclosure] When positioning multiple optical fibers using guide pins and ferrules with guide pin insertion holes, as in the technology disclosed in Patent Document 1, the following problems may arise. For example, in order to position multiple optical fibers with high precision, guide pins with high dimensional accuracy are required so that the clearance between the guide pins and the guide pin insertion holes is minimized. Furthermore, when cleaning a ferrule with guide pins inserted into its guide pin insertion holes, it may not be possible to completely remove foreign matter such as dust near the guide pins. In such cases, the foreign matter may interfere with the positioning precision of the multiple optical fibers, resulting in increased connection loss.

[0009] The ferrule, optical connector, and optical connection structure according to the present disclosure enable easy positioning of multiple optical fibers with a simple configuration.

[0010] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. A ferrule according to one embodiment of the present disclosure comprises an optical fiber holding part configured to hold a plurality of optical fibers, and a first side surface and a second side surface facing each other in a second direction intersecting a first direction in which the optical fiber holding part extends. The first side surface is provided with a first recess or a first protrusion extending along the first direction. The second side surface is provided with a second recess or a second protrusion extending along the first direction. The first recess or the first protrusion has a first positioning part and a second positioning part that are spaced apart from each other in the first direction.

[0011] This ferrule has a first recess or a first protrusion on the first side surface and a second recess or a second protrusion on the second side surface. When the ferrule is inserted into an adapter having an inner surface corresponding to this shape, the first recess or the first protrusion and the second recess or the second protrusion fit into the inner surface of the adapter, thereby determining the position of the ferrule relative to the adapter in a plane perpendicular to the first direction (i.e., the positions of the optical fibers held in the ferrule). In other words, with this ferrule configuration, the adapter into which the ferrule is inserted and fitted serves as a positioning member for positioning the optical fibers, thereby enabling the positioning of the optical fibers without providing guide pin insertion holes in the ferrule. As a result, there is no need to use guide pins with high dimensional accuracy for positioning the optical fibers. Furthermore, this avoids the problem of reduced positioning accuracy between the optical fibers due to the use of guide pins with foreign matter attached, thereby suppressing a decrease in connection loss.

[0012] Furthermore, in this ferrule, more specifically, the first positioning portion and the second positioning portion, which contact the inner surface of the adapter on the first side surface to position the ferrule relative to the adapter, are provided spaced apart from each other on the first side surface, and the ferrule is positioned using these portions. With this configuration, positioning is performed by contacting limited portions such as the first positioning portion and the second positioning portion with the inner surface of the adapter, rather than the entire first side surface, so only these positioning portions need to be highly dimensionally accurate, and the optical fiber held in the ferrule can be positioned with high precision even without requiring high dimensional accuracy for the entire first side surface. In other words, by providing high dimensional accuracy for at least two spaced positioning portions in this ferrule, it becomes possible to easily manage tilt or misalignment of the ferrule when fitting the ferrule to the adapter. Note that ferrules for optical connectors are typically manufactured using, for example, an injection molding machine. molding For example, when a ferrule is manufactured by a method such as injection molding, a portion of the first side surface may shrink after molding, making it difficult to manufacture the entire first side surface, which consists of a continuous V-groove, with high dimensional accuracy. However, by using a portion of the first side surface as a positioning portion that contacts the inner surface of the adapter as described above, the portion for which dimensional accuracy is to be increased is limited, making it possible to easily manufacture a ferrule that can be positioned with high accuracy relative to the adapter even when manufactured by injection molding, etc. As described above, the ferrule described above allows for easy positioning of multiple optical fibers with a simple configuration.

[0013] In one embodiment, the first recess or first protrusion may further include a first step portion located between the first positioning portion and the second positioning portion and extending along the first direction. The first step portion may be recessed deeper into the ferrule than the surfaces of the first positioning portion and the second positioning portion. This embodiment allows the first positioning portion and the second positioning portion to reliably contact the inner surface of the adapter, making it possible to easily position the ferrule. Furthermore, even if the first step portion does not have high dimensional accuracy, it is possible to eliminate the influence of the first positioning portion and the second positioning portion on positioning. In this embodiment, the first step portion may be recessed within a range of 0.005 mm to 2 mm from the surfaces of the first positioning portion and the second positioning portion.

[0014] In one embodiment, the first positioning portion and the second positioning portion may be spaced apart from each other by a distance of 1 mm to 10 mm in the first direction. According to this embodiment, the first positioning portion and the second positioning portion are positioned apart from each other by 1 mm or more and contact the inner surface of the adapter in this state. This allows for more accurate positioning of the ferrule relative to the adapter than when the first positioning portion and the second positioning portion are close to each other (closer than 1 mm). Furthermore, by setting the distance between the first positioning portion and the second positioning portion to 10 mm or less, the ferrule can be made compact without increasing its size. The distance here refers to the shortest distance between the first positioning portion and the second positioning portion, i.e., the distance between the end of the first positioning portion closest to the second positioning portion and the end of the second positioning portion closest to the first positioning portion.

[0015] In one embodiment, the first positioning portion and the second positioning portion may be formed inward so as to be at least 0.1 mm away from the adjacent end faces or flanges of the ferrules in the first direction. According to this embodiment, when inserting or removing the ferrule into or from the adapter, the first positioning portion or the second positioning portion does not interfere with the operation, allowing for smooth insertion and removal.

[0016] In one embodiment, the width of each of the first positioning portion and the second positioning portion along the first direction may be 0.5 mm or more and 3 mm or less. According to this embodiment, when the ferrule is inserted into the adapter, the first positioning portion and the second positioning portion can be more reliably brought into contact with the inner surface of the adapter, and the first positioning portion and the second positioning portion can more accurately position the ferrule relative to the adapter.

[0017] In one embodiment, the first positioning portion and the second positioning portion may each be V-shaped or U-shaped in a cross section perpendicular to the first direction if they are the first recessed portion, or may be a semicircular protrusion or an elliptical protrusion if they are the first protruding portion. According to this embodiment, the shapes of the first positioning portion and the second positioning portion can be simplified, and the simplified configuration makes it easy to increase the dimensional accuracy of the first positioning portion and the second positioning portion.

[0018] In one embodiment, the second recess or second protrusion may have a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction, and a second step portion that is located between the third positioning portion and the fourth positioning portion and extends along the first direction. The second step portion may be recessed further inward of the ferrule than the surfaces of the third positioning portion and the fourth positioning portion. According to this embodiment, as with the first side surface, positioning is performed on the second side surface by bringing limited portions such as the third positioning portion and the fourth positioning portion into contact with the inner surface of the adapter, rather than the entire second side surface. Therefore, it is only necessary to provide high dimensional accuracy for only these positioning portions, and the positioning of the optical fiber held in the ferrule can be performed with high precision even without providing high dimensional accuracy for the entire second side surface. Furthermore, when this ferrule is, for example, ejected, molding Even when the ferrule is manufactured by the above method, by making a part of the second side surface a positioning part that contacts the inner surface of the adapter, it is possible to limit the part where dimensional accuracy is to be increased, and to easily manufacture a ferrule that can be positioned with high accuracy relative to the adapter. Furthermore, as with the first step part, even if the second step part does not have high dimensional accuracy, it is possible to eliminate the influence of the third positioning part and the fourth positioning part on positioning.

[0019] In the above embodiments, the locations of the third and fourth positioning portions on the second recess or second protrusion in the first direction may correspond to the locations of the first and second positioning portions on the first recess or first protrusion in the first direction. In this case, when the ferrule is inserted into the adapter and positioned, it is possible to improve left-right balance and position the ferrule more accurately. Note that, as an example, the locations of the third and fourth positioning portions corresponding to the locations of the first and second positioning portions means that the locations of the third and fourth positioning portions and the locations of the first and second positioning portions are provided in the same place in the first direction.

[0020] In one embodiment, the ferrule may further include a first end face and a second end face facing each other in a first direction. The first end face may be provided with a plurality of lenses or a plurality of through holes corresponding to a plurality of optical fibers. The second end face may be provided with an opening into which a plurality of optical fibers can be inserted all at once. This embodiment enables the ferrule to be positioned relative to the adapter with a simpler configuration. Note that this ferrule may be configured such that the first end face does not have a hole for a positioning pin for positioning the ferrule relative to another ferrule to be connected.

[0021] An optical connector according to an embodiment of the present disclosure includes a ferrule according to any of the above-described embodiments and a plurality of optical fibers held in an optical fiber holding portion. This optical connector can achieve the same effects as those of the above-described ferrule embodiments.

[0022] An optical connection structure according to an embodiment of the present disclosure includes a plurality of optical fibers, a ferrule that holds the plurality of optical fibers, and an adapter. The adapter is cylindrical and configured so that the ferrule is inserted into and fitted with another ferrule to be connected, with the ferrule facing each other inside the cylindrical shape. The ferrule has a first side surface and a second side surface that face each other in a second direction that intersects with a first direction in which the ferrule is inserted into the adapter. The first side surface is provided with a first recess or a first protrusion extending along the first direction. The second side surface is provided with a second recess or a second protrusion extending along the first direction. The inner surface of the adapter is provided with a third protrusion that can be fitted with the first recess or the third recess that can be fitted with the first protrusion, and a fourth protrusion that can be fitted with the second recess or the fourth recess that can be fitted with the second protrusion. In this optical connection structure, the first recess or first convex portion has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and the second recess or second convex portion has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction, or the third convex portion or third recess has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and the fourth convex portion or fourth recess has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction.

[0023] According to the optical connection structure, similar to the above-described embodiments of the ferrule, it is possible to position a plurality of optical fibers with a simple configuration.

[0024] In one embodiment of the optical connection structure, when the first recess or first protrusion has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and the second recess or second protrusion has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction, the first recess or first protrusion may further have a step portion that is located between the first positioning portion and the second positioning portion and extends along the first direction. The step portion is located between the first positioning portion and the second positioning portion and is spaced apart from each other in the first direction. FerruleAccording to this embodiment, the first positioning portion and the second positioning portion can be brought into reliable contact with the inner surface of the adapter, making it possible to easily position the ferrule.

[0025] In one embodiment of the optical connection structure, when the first recess or first protrusion has a first positioning portion and a second positioning portion that are spaced apart in the first direction, and the second recess or second protrusion has a third positioning portion and a fourth positioning portion that are spaced apart in the first direction, the first positioning portion and the second positioning portion may be contactable with the third protrusion or the third recess in a plane perpendicular to the first direction, and the third positioning portion and the fourth positioning portion may be contactable with the fourth protrusion or the fourth recess. According to this embodiment, the positioning of the ferrule with respect to the adapter can be achieved with a simple configuration.

[0026] In one embodiment of the optical connection structure, when the first recess or first protrusion has a first positioning portion and a second positioning portion that are spaced apart in the first direction, and the second recess or second protrusion has a third positioning portion and a fourth positioning portion that are spaced apart in the first direction, at least one of the third protrusion or third recess and the fourth protrusion or fourth recess may be configured to be elastically deformable in the second direction. This embodiment facilitates insertion of the ferrule into the adapter, improving workability when inserting the ferrule into the adapter. Furthermore, when the first recess or first protrusion and the second recess or second protrusion abut against the third protrusion or third recess and the fourth protrusion or fourth recess, respectively, a force is applied to the ferrule that causes at least one of the third protrusion or third recess and the fourth protrusion or fourth recess to return to their original positions. This allows the ferrule to be clamped and fixed between the third convex portion or the third concave portion and the fourth convex portion or the fourth concave portion, thereby preventing the ferrule from shifting in position relative to the adapter, thereby enabling accurate positioning of multiple optical fibers.

[0027] [Details of the embodiments of the present disclosure] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the following description, the same elements or elements having the same functions will be designated by the same reference numerals, and redundant explanations will be omitted.

[0028] FIG. 1 is a perspective view showing a state in which the optical connector 2 is attached to the adapter 20 in the optical connection structure 1. FIG. 2 is a perspective view showing a state in which the optical connector 2 is detached from the adapter 20 in the optical connection structure 1. For ease of understanding, an XYZ Cartesian coordinate system is shown in FIGS. 1 and 2. This is also true for the other figures. In this embodiment, the longitudinal direction of the optical connector 2, which is the direction in which the optical connector 2 is inserted into the adapter 20, is defined as the Z direction (first direction), the lateral direction of the optical connector 2 is defined as the Y direction (second direction), and the height direction of the optical connector 2 is defined as the X direction (third direction).

[0029] As shown in FIGS. 1 and 2, the optical connection structure 1 includes an optical connector 2 having a ferrule 10, and an adapter 20 into which the optical connector 2 can be inserted and removed. The optical connector 2 includes an optical fiber ribbon 4 accommodating multiple optical fibers 3, a boot 5, and a ferrule 10 attached to the tip of the optical fiber ribbon 4 via the boot 5. The optical fibers 3 of the optical fiber ribbon 4 extend along the Z direction and are arranged side by side along the Y direction intersecting (e.g., perpendicular to) the Z direction. The optical fiber ribbon 4 may have a configuration in which multiple optical fibers 3 are arranged in multiple layers inside. The multiple optical fibers 3 are inserted and held along the Z direction in multiple optical fiber grooves (see FIG. 4, described later) or multiple optical fiber holding holes formed inside the ferrule 10.

[0030] The ferrule 10 has, for example, a substantially rectangular parallelepiped appearance, and is a component for storing a plurality of optical fibers 3 therein and optically coupling each optical fiber 3 to a plurality of other optical fibers held in ferrules (not shown) of another optical connector. The ferrule 10 is insertable into and removable from the adapter 20 along the Z direction to achieve this optical coupling. Note that the other optical connector may have a configuration similar to that of the optical connector 2. The ferrule 10 has a main body 11 and a flange 12, and is formed so that the flange 12 is larger than the main body 11 in a cross section along the XY plane.

[0031] The main body 11 has recesses 15 and 16 (first and second recesses) on both side surfaces 13 and 14, and these recesses 15 and 16 extend along the Z direction. The recesses 15 and 16 are, for example, V-grooves or U-grooves (having a V- or U-shaped cross section) extending in the Z direction, and function as guide grooves when the ferrule 10 is inserted into or removed from the adapter 20. The recesses 15 and 16 may not be formed in the collar 12, or may extend to the collar 12. The ferrule 10 is made of a material such as polyphenylene sulfide (PPS), polyetherimide (PEI), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethersulfone (PES), or cycloolefin polymer (COP). The ferrule 10 is inserted into the adapter 20 along the Z direction, for example, and fitted to the adapter 20.

[0032] The adapter 20 is cylindrical and can accommodate the ferrule 10 therein. The ferrule 10 and another ferrule to be connected are inserted and fitted together so that they face each other inside the cylindrical adapter 20. Inside the adapter 20, the front end face 17 of the ferrule 10 and the front end face of the other ferrule to be connected may abut against each other to be optically coupled, or may be optically coupled at a predetermined distance. More specifically, the adapter 20 has a storage section 22 that opens at the front end face 21 and is configured so that the ferrule 10 can be inserted into the storage section 22. The storage section 22 extends through to the rear end face of the adapter 20, which is on the opposite side in the Z direction from the front end face 21, and the other ferrule described above is configured to be inserted through the opening at the rear end face.

[0033] Convex portions 23, 24 (third convex portion and fourth convex portion) facing each other in the Y direction are provided on both inner surfaces of the storage portion 22 of the adapter 20. The convex portions 23, 24 protrude toward the inside of the adapter 20. When the ferrule 10 is inserted into the adapter 20, the convex portions 23, 24 enter and contact the recessed portions 15, 16 of the ferrule 10, and guide the ferrule 10 when inserted into and removed from the adapter 20. Gaps 25, 26 may be further provided outside the convex portions 23, 24 of the adapter 20. The provision of the gaps 25, 26 allows the convex portions 23, 24 to easily move elastically outward in the Y direction. Therefore, even if the convex portions 23, 24 of the adapter 20 are formed somewhat narrow so as to reliably contact the recessed portions 15, 16 of the ferrule 10, the convex portions 23, 24 can still move outward when the adapter 20 is inserted.

[0034] Since the optical connection structure 1 includes the recesses 15, 16 and the protrusions 23, 24, when the ferrule 10 is inserted into the adapter 20, the position of the ferrule 10 (i.e., the multiple optical fibers 3 of the optical connector 2) relative to the adapter 20 in the X and Y directions and the rotations about each of the X, Y, and Z axes can be restricted, thereby positioning the ferrule 10, without providing a guide pin. Furthermore, if the optical connector 2 has an external housing that is biased forward by an elastic member such as a spring and that houses the optical connector 2 therein, the movement of the ferrule 10 in the Z direction may be restricted by the external housing coming into contact with the adapter 20 or by a spring or the like, or the adapter 20 may be provided with a configuration that restricts movement of the ferrule 10 in the Z direction.

[0035] When a corresponding optical connector is inserted into the adapter 20 positioned in this manner from the opposite side, the front end face 17 of the ferrule 10 faces the front end face of the mating ferrule (not shown), and the two are optically coupled. The adapter 20 is made of an elastic material, such as polyetherimide (PEI), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethersulfone (PES), or polyamide (PA). To minimize the difference in the linear expansion coefficient between the material of the adapter 20 and the material of the ferrule 10, it is preferable to use the same material as the ferrule 10 for the material of the adapter 20. The material of the adapter 20 may also contain a filler or an additive to improve sliding properties.

[0036] Next, the shape of the ferrule 10 to be inserted into the adapter 20 will be described in more detail with reference to FIGS. 3 and 4. FIG. 3 is a perspective view showing an optical connector 2 including a ferrule 10 according to one embodiment. FIG. 4 is a perspective view showing the ferrule 10. As described above, the ferrule 10 includes a main body 11, a flange 12, side surfaces 13 and 14, recesses 15 and 16, a front end face 17, a rear end face 18, and a lens group 19. The ferrule 10 further includes windows 11a and 11b on the top surface of the main body 11, and a plurality of grooves 11c (optical fiber holding portions) for holding a plurality of optical fibers 3 are formed inside the window 11a. The plurality of grooves 11c may be, for example, V-grooves or U-grooves, and extend along the Z direction. Alternatively, a plurality of through holes for holding optical fibers may be provided in the ferrule 10 instead of the plurality of grooves 11c.

[0037] The optical fibers 3 constituting the optical connector 2 are inserted into a storage section continuing from the rear end face 18 of the ferrule 10, with their tip portions stored in the grooves 11c and arranged in predetermined positions. Each optical fiber 3 stored in an aligned state in the grooves 11c is optically coupled from inside the ferrule to each lens of a lens group 19 provided on the outside of the ferrule 10 (in this case, the portion of the ferrule 10 up to the lens group 19 is made of, for example, at least, an optically transparent resin). After the optical fibers 3 are stored in the grooves 11c, the lid 6 is fitted into the window 11a from above in the X direction to press and position the optical fibers 3 against the grooves 11c, and a fixing adhesive or the like is injected from the window 11a (the gap with the lid 6) or the window 11b to fix the optical fibers 3 to the grooves 11c or the like.

[0038] The recess 15 provided on the side surface 13 of the ferrule 10 includes two positioning portions 15a and 15b (first positioning portion and second positioning portion), a step portion 15c located between the positioning portions 15a and 15b, a step portion 15d located outside the positioning portion 15a, and a step portion 15c located outside the positioning portion 15a. 15band the flange portion 12. Each of the step portions 15c, 15d, and 15e is recessed further inward of the ferrule 10 than the surfaces of the positioning portions 15a and 15b. In other words, the positioning portions 15a and 15b are configured to protrude slightly outward from the step portions 15c, 15d, and 15e. When the ferrule 10 is inserted into the adapter 20, the two positioning portions 15a and 15b come into contact with the protrusion 23 of the adapter 20 (see FIG. 2), and the step portions 15c, 15d, and 15e do not come into contact with (or only slightly touch) the protrusion 23 of the adapter 20. The recess amount of the step portions 15c, 15d, 15e may be, for example, such that the difference between each surface of the positioning portions 15a, 15b and the bottom surface of each step portion 15c, 15d, 15e is 0.005 mm or more and 2 mm or less, which is a slight step that does not hinder contact in the Y direction between the positioning portions 15a, 15b and the protrusion 23 of the adapter 20. However, the difference between each surface of the positioning portions 15a, 15b and the bottom surface of each step portion 15c, 15d, 15e may be greater than 2 mm.

[0039] The positioning portions 15a, 15b are spaced apart from each other in the Z-axis direction, and the distance may be, for example, 1 mm or more and 10 mm or less. The distance here refers to the shortest distance between the positioning portions, for example, the distance between the end of the positioning portion 15a closest to the positioning portion 15b and the end of the positioning portion 15b closest to the positioning portion 15a. The positioning portion 15a is formed inward in the Z-axis direction so that its end is at least 0.1 mm away from the adjacent front end face 17 of the ferrule 10. "Inward" here means that the positioning portion 15a is located closer to the collar portion 12 in the Z-axis direction than the front end face 17. The positioning portion 15b is formed inward in the Z-axis direction so that its end is at least 0.1 mm away from the adjacent collar portion 12 of the ferrule 10. "Inward" here means that the positioning portion 15b is located closer to the front end face 17 in the Z-axis direction than the collar portion 12. With the above configuration, a step 15d is formed between the positioning portion 15a and the front end face 17, and a step 15e is formed between the positioning portion 15b and the flange portion 12. Furthermore, each of the positioning portions 15a, 15b may have a width along the Z-axis direction of 0.5 mm to 3 mm. By having a certain width, when inserted into the adapter 20, a contact area with the adapter 20 is ensured, and the ferrule 10 (or the multiple optical fibers 3 held therein) can function as a location for more appropriately positioning the adapter 20.

[0040] Similarly to recess 15, recess 16 provided on side surface 14 of ferrule 10 has two positioning portions 16a and 16b (third positioning portion and fourth positioning portion), a step portion 16c located between positioning portions 16a and 16b, a step portion 16d located outside positioning portion 16a, and a step portion 16e located between positioning portion 16b and flange portion 12. Recess 16 has a shape that is line-symmetrical with recess 15 about a central axis that passes through the center of ferrule 10 in the Y direction and extends in the Z-axis direction, positioning portions 16a and 16b have a shape that is line-symmetrical with positioning portions 15a and 15b, and step portions 16c, 16d, and 16e have a shape that is line-symmetrical with step portions 15c, 15d, and 15e (i.e., a shape that is bilaterally symmetrical). For this reason, the positioning portions 16a and 16b are provided on the side surface 14 so as to be at the same positions in the Z direction as the positioning portions 15a and 15b on the side surface 13. Furthermore, the step portions 16c, 16d, and 16e are recessed further inward into the ferrule 10 than the surfaces of the positioning portions 16a and 16b. In other words, the positioning portions 16a and 16b are configured to protrude slightly outward beyond the step portions 16c, 16d, and 16e. The other configurations of the positioning portions 16a and 16b and the step portions 16c, 16d, and 16e are the same as those of the positioning portions 15a and 15b and the step portions 15c, 15d, and 15e described above, and detailed description thereof will be omitted.

[0041] When the positioning portions 15a, 15b, 16a, and 16b of the recesses 15 and 16 have a V-shaped cross section, the opening angle of the V (i.e., the angle between a pair of surfaces constituting the V-groove) in a cross section perpendicular to the Z direction may be, for example, 45° or more and 150° or less. The opening angle of the V-groove of the positioning portions 15a, 15b, 16a, and 16b may be, for example, 60° or more and 100° or less, or may be 90°. Furthermore, the bottom of the V-groove constituting each positioning portion 15a, 15b, 16a, and 16b may be, for example, rounded in a cross section perpendicular to the Z direction. The distance between the bottoms of the positioning portions 15a, 15b of the recess 15 and the bottoms of the positioning portions 16a, 16b of the recess 16, which face each other along the Y direction, is formed to be slightly wider than the distance between the tips of the convex portions 23, 24 of the adapter 20. As a result, when the ferrule 10 is inserted into the adapter 20, the ferrule 10 is positioned at a predetermined position relative to the adapter 20 by the positioning portions 15a, 15b of the recess 15 and the positioning portions 16a, 16b of the recess 16.

[0042] As described above, in the ferrule 10 according to this embodiment, positioning to the adapter 20 or another ferrule is performed by the positioning portions 15a, 15b, 16a, and 16b on both side surfaces 13 and 14, and therefore no guide pin insertion holes are provided in the front end face 17 between the side surfaces 13 and 14 and the lens group 19. This allows the location of the lens group 19 on the front end face 17 to be determined without considering the outer diameter of the guide pin insertion holes. In this case, the size of the ferrule 10 can be reduced by the amount that the guide pin insertion holes are not provided. Note that instead of the lens group 19, through holes corresponding to each optical fiber 3 may be provided so that the tip of the optical fiber 3 can be inserted and exposed at the front end face 17.

[0043] As described above, the ferrule 10 according to this embodiment has the recess 15 on the side surface 13 and the recess 16 on the side surface 14. When the ferrule 10 is inserted into the adapter 20 having an inner surface (protrusions 23, 24) corresponding to the recess 15, the recess 16 is fitted into the inner surface of the adapter 20, thereby defining the position of the ferrule 10 relative to the adapter 20 in a plane perpendicular to the Z direction (i.e., the positions of the multiple optical fibers 3 held in the ferrule 10). In other words, with this ferrule configuration, the adapter 20 into which the ferrule 10 is inserted and fitted serves as a positioning member for positioning the multiple optical fibers 3, thereby enabling the multiple optical fibers 3 to be positioned without providing guide pin insertion holes in the ferrule 10. As a result, it is not necessary to use guide pins with high dimensional accuracy for positioning the multiple optical fibers 3. Furthermore, since it is possible to avoid a situation in which the positioning accuracy of the multiple optical fibers 3 is reduced due to the use of guide pins with foreign matter attached, it is possible to suppress a decrease in connection loss.

[0044] More specifically, in this ferrule 10, two positioning portions 15a, 15b that contact the inner surface of the adapter on side surface 13 to position the ferrule 10 relative to the adapter are provided spaced apart from each other on side surface 13, and these portions position one side of the ferrule 10. Also, two positioning portions 16a, 16b that contact the inner surface of the adapter on side surface 14 to position the ferrule 10 relative to the adapter are provided spaced apart from each other on side surface 14, and these portions position the other side of the ferrule 10. With this configuration, positioning is performed by contacting limited portions such as positioning portions 15a, 15b and 16a, 16b with the inner surface of the adapter, rather than the entire side surfaces 13, 14, so only these positioning portions need to be highly dimensionally accurate, and the optical fiber 3 held in the ferrule 10 can be positioned with high precision even if the entire side surfaces 13, 14 do not require high dimensional accuracy. That is, in this ferrule 10, by providing high dimensional accuracy to at least two mutually separated positioning portions 15a, 15b and 16a, 16b, it becomes possible to easily control the inclination or positional deviation of the ferrule 10 when the ferrule 10 is fitted to the adapter 20. Incidentally, a ferrule for an optical connector is, for example, an injection mold. molding However, by forming the side surfaces 13 and 14 as positioning portions 15a, 15b, 16a, and 16b that contact the inner surface of the adapter as described above, the portions for which dimensional accuracy is to be increased are limited, and it is thereby possible to easily manufacture a ferrule 10 that can be positioned with high accuracy relative to the adapter 20 even when manufactured by injection molding or the like. molding As described above, the ferrule 10 allows the positioning of a plurality of optical fibers 3 to be easily performed with a simple configuration.

[0045] In this embodiment, the recesses 15, 16 further have step portions 15c, 16c located between the positioning portions and extending along the Z direction, and the step portions 15c, 16c are recessed further inward of the ferrule 10 than the surfaces of the positioning portions 15a, 16a, etc. This allows the positioning portions 15a, 15b and 16a, 16b to reliably contact the inner surface of the adapter 20, making it possible to easily position the ferrule 10. Furthermore, even if the step portions 15c, 16c do not have high dimensional accuracy, it is possible to eliminate the influence of the positioning portions 15a, 15b and 16a, 16b on positioning.

[0046] In this embodiment, the positioning portions 15a and 15b may be spaced apart from each other by a distance of 1 mm to 10 mm in the Z direction. In this case, the positioning portions 15a and 15b are positioned apart from each other by 1 mm or more and contact the inner surface of the adapter in this state, which allows for more accurate positioning of the ferrule 10 relative to the adapter 20 than when the positioning portions are close to each other (closer than 1 mm). Furthermore, by setting the distance between the positioning portions 15a and 15b to 10 mm or less, the ferrule 10 can be made compact without increasing its size. The same applies to the distance between the positioning portions 16a and 16b.

[0047] In this embodiment, the positioning portions 15a, 15b may be formed inward in the Z direction so as to be at least 0.1 mm away from the adjacent front end face 17 of the ferrule 10 or the adjacent flange portion 12 of the ferrule 10. In this case, when inserting or extracting the ferrule 10 into or from the adapter 20, the positioning portion 15a or the positioning portion 15b is prevented from interfering with the operation, enabling smooth insertion and extraction. The same applies to the arrangement locations of the positioning portions 16a, 16b.

[0048] In this embodiment, the width of each of the positioning portions 15a, 15b and 16a, 16b along the Z direction may be 0.5 mm or more and 3 mm or less. In this case, when the ferrule 10 is inserted into the adapter 20, each positioning portion can be more reliably brought into contact with the inner surface of the adapter, and the positioning portion can more accurately position the ferrule relative to the adapter.

[0049] In this embodiment, each of the positioning portions 15a, 15b, 16a, and 16b may be V-shaped or U-shaped in a cross section perpendicular to the Z direction. In this case, the shape of each positioning portion can be simplified, and the simplified configuration makes it easy to increase the dimensional accuracy of each positioning portion.

[0050] In this embodiment, the locations of the positioning portions 16a and 16b in the recess 16 in the Z direction correspond to the locations of the positioning portions 15a and 15b in the recess 15 in the Z direction. That is, the side shapes of the recess 16 and the recess 15 are symmetrical about the central axis of the ferrule 10. Therefore, when the ferrule 10 is inserted into the adapter 20 and positioned, it is possible to improve the left-right balance and position the ferrule 10 with greater accuracy.

[0051] In this embodiment, the ferrule 10 further includes a front end face 17 and a rear end face 18 that face each other in the Z direction, and the front end face 17 is provided with a plurality of lenses of a lens group 19 corresponding to a plurality of optical fibers 3 or a plurality of through holes, and the rear end face 18 is provided with an opening into which a plurality of optical fibers 3 can be inserted all at once. Furthermore, the front end face 17 of the ferrule 10 does not have holes for positioning pins that position the ferrule 10 relative to another ferrule to be connected. This makes it possible to position the ferrule 10 relative to the adapter 20 with a simpler configuration.

[0052] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the claims.

[0053] For example, a modified example of an optical connection structure including an optical connector 2 including the above-described ferrule 10 will be described with reference to Figs. 5, 6, and 7. In this modified example, an adapter 50 differs from the adapter 20 according to the above embodiment. Fig. 5 is a perspective view showing the optical connection structure 51. Fig. 6 is a plan view showing the optical connection structure 51. Fig. 7 is a cross-sectional view showing the optical connection structure 51. Note that the optical connectors shown in Figs. 5, 6, and 7 are shown in a state where the multiple optical fibers 3 and the like are omitted (i.e., where only the ferrule 10 is shown). Furthermore, Figs. 5 and 6 show the adapter 50 of the optical connection structure 51 as a cross section when cut along the YZ plane.

[0054] 5 and 6, an optical connection structure 51 includes a pair of optical connectors 2, 2 arranged to face each other in the Z direction, and an adapter 50 into which the pair of optical connectors 2, 2 are inserted. The pair of optical connectors 2, 2 are arranged upside down (facing each other in the X direction) and are fitted into the adapter 50 so that the front end faces 17, 17 of the ferrules 10, 10 face each other inside the adapter 50 (see FIG. 4, for example). Inside the adapter 50, the front end faces 17, 17 of the pair of ferrules 10, 10 may abut against each other and be in contact with each other, or may face each other with a predetermined distance between them.

[0055] The adapter 50 has a cylindrical shape capable of accommodating the pair of ferrules 10, 10, and extends along the Z direction. The overall length of the adapter 50 in the Z direction is longer than, for example, the combined length of the pair of ferrules 10, 10 when connected to each other. As shown in FIG. 7 , the adapter 50 has a rectangular cylindrical shape when viewed from the Z direction. The adapter 50 has an insertion hole 56 that forms the interior of the rectangular cylindrical shape. The insertion hole 56 penetrates the adapter 50 in the Z direction. The insertion hole 56 has a substantially rectangular shape when viewed from the Z direction, and is composed of four inner surfaces 52, 53, 54, and 55.

[0056] The inner surface 52 faces the outer surface (top surface) of the ferrule 10 in the X direction, and the inner surface 53 faces the outer surface (bottom surface) of the ferrule 10 in the X direction. The inner surface 54 faces the side surface 13 of the ferrule 10 in the Y direction, and the inner surface 55 faces the side surface 14 of the ferrule 10 in the Y direction. The inner surfaces 54 and 55 are provided with V-shaped protrusions 54a and 55a, respectively, for guiding the positioning portions 15a and 15b of the recess 15 of the ferrule 10 and the positioning portions 16a and 16b of the recess 16. The V-shaped protrusions 54a and 55a are disposed symmetrically with each other with respect to the center of the insertion hole 56 in the Y direction. The V-shaped protrusions 54a are V-shaped in the XY cross section. The V-shaped protrusions 54a protrude from the inner surface 54 toward the side surface 13 of the ferrule 10 and abut against the positioning portions 15a and 15b of the recess 15 on the side surface 13. The V-shaped protrusion 54a is provided, for example, on the inner surface 54, so as to extend continuously along the Z direction. The V-shaped protrusion 55a is a protrusion that is V-shaped in the XY cross section. The V-shaped protrusion 55a protrudes from the inner surface 55 toward the side surface 14 of the ferrule 10 and abuts against the positioning portions 16a, 16b of the recess 16. The V-shaped protrusion 55a is provided, for example, on the inner surface 55, so as to extend continuously along the Z direction.

[0057] The V-shaped protrusion 54a has a shape corresponding to the positioning portions 15a and 15b of the recess 15, and the opening angle of the V-shaped protrusion 54a (i.e., the angle formed by the pair of outer surfaces constituting the V-shaped protrusion 54a) is set smaller than the opening angle of the positioning portions 15a and 15b of the recess 15 of the ferrule 10. The top of the V-shaped protrusion 54a is, for example, rounded and has a substantially circular shape. The V-shaped protrusion 55a has a shape corresponding to the positioning portions 16a and 16b of the recess 16, and has the same shape (e.g., rounded top) as the V-shaped protrusion 54a. The separation distance in the Y direction between the V-shaped protrusion 54a and the V-shaped protrusion 55a is set slightly smaller than the width in the Y direction between the positioning portions 15a (15b) of the recess 15 of the ferrule 10 and the positioning portions 16a (16b) of the recess 16. The separation distance in the Y direction between the V-protrusion 54a and the V-protrusion 55a can be defined as the distance in the Y direction between the top of the V-protrusion 54a and the top of the V-protrusion 55a when the ferrule 10 is not inserted into the adapter 50. The width in the Y direction between the positioning portion 15a (15b) of the recess 15 and the positioning portion 16a (16b) of the recess 16 can be defined as the distance in the Y direction between the bottom of the positioning portion 15a (15b) of the recess 15 and the bottom of the positioning portion 16a (16b) of the recess 16. In this optical connection structure 51, when the ferrule 10 is inserted into the adapter 50, the positioning portions 15a and 15b of the recess 15 of the ferrule 10 circumscribe an imaginary circle of the rounded portion at the tip of the V-protrusion 54a, and the positioning portions 16a and 16b of the recess 16 of the ferrule 10 circumscribe an imaginary circle of the rounded portion at the tip of the V-protrusion 55a. Such a connection structure allows the ferrule 10 to be properly positioned relative to the adapter 50 .

[0058] The adapter 50 further includes a hollow portion 61 provided on one side of the insertion hole 56 in the Y direction. The hollow portion 61 is located outside the insertion hole 56 in the Y direction, sandwiching a wall portion 54W constituting the inner surface 54 therebetween. In other words, the hollow portion 61 is separated from the insertion hole 56 in the Y direction by the wall portion 54W. The hollow portion 61 extends linearly along the Z direction, for example, at a position aligned with the insertion hole 56 in the Y direction. The wall portion 54W extends in the X direction between the hollow portion 61 and the insertion hole 56 to separate them. The thickness of the wall portion 54W (i.e., the width of the wall portion 54W in the Y direction) is, for example, constant. The thickness of the wall portion 54W is sufficiently thin to allow elastic deformation of the V-shaped protrusion 54a. Similarly, the thickness of the wall portion constituting the inner surface 55 is also sufficiently thin to allow elastic deformation of the V-shaped protrusion 55a. It should be noted that no hollow portion is provided on the other outer side of the insertion hole 56 in the Y direction.

[0059] In the optical connection structure 51 described above, when the ferrule 10 is inserted into the adapter 50, the positioning portions 15a and 15b of the recess 15 of the ferrule 10 and the positioning portions 16a and 16b of the recess 16 are aligned. 16b are fitted into the V-shaped protrusions 54a and 55a of the adapter 50. At this time, the V-shaped protrusions 54a enter and come into contact with the positioning portions 15a and 15b of the recess 15 of the ferrule 10, and the V-shaped protrusions 55a are fitted into the positioning portions 16a and 16b of the recess 16 of the ferrule 10. As described above, the distance between the V-shaped projections 54a and 55a of the adapter 50 is set to be smaller than the width between the positioning portions 15a (15b) of the recess 15 of the ferrule 10 and the positioning portions 16a (16b) of the recess 16. Therefore, the V-shaped projections 54a and 55a of the adapter 50 receive reaction forces from the positioning portions 15a, 15b of the recess 15 of the ferrule 10 and the positioning portions 16a, 16b of the recess 16, and the V-shaped projections 54a and 55a of the adapter 50 move in the Y direction. The ferrule 10 is elastically deformed outward from the ferrule 10. Then, a force acts on the ferrule 10 as the V-projections 54a and 55a of the adapter 50 return to their original positions, and the ferrule 10 is clamped and fixed between the V-projections 54a and 55a of the adapter 50.

[0060] As a result, the V-shaped protrusions 54a and 55a of the adapter 50 come into contact with the positioning portions 15a and 15b of the recess 15 of the ferrule 10 and the positioning portions 16a and 16b of the recess 16, respectively. The gap in the Y direction between the V-shaped protrusion 54a and the positioning portions 15a and 15b of the recess 15, and the gap in the Y direction between the V-shaped protrusion 55a and the positioning portions 16a and 16b of the recess 16, are both zero. This defines the position of the ferrule 10 relative to the adapter 50 in the XY plane, and also defines the rotational position of the ferrule 10 relative to the adapter 50. Thereafter, a spring (not shown) attached to the rear of the ferrule 10 biases the ferrule 10 in the Z direction toward the mating ferrule 10, thereby defining the position of the ferrule 10 in the Z direction relative to the adapter 50. In this way, the position of the ferrule 10 relative to the adapter 50 is defined.

[0061] In this modification, the V-projection 54a and the V-projection 55a are components that constitute a part of the adapter 50, which is made of an elastic material, and therefore both the V-projection 54a and the V-projection 55a are configured to be elastically deformable. However, for example, only the V-projection 54a may be configured to be elastically deformable, and the V-projection 55a may not be configured to be elastically deformable. In this modification, since the hollow portion 61 is provided outside the wall portion 54W on which the V-projection 54a is provided, if the portion near the wall portion 54W is made of an elastic material, only the V-projection 54a can be configured to be elastically deformable. In this case, when the ferrule 10 is inserted into the adapter 50, the ferrule 10 is inserted into the V-projection 55a, which does not elastically deform. 10The adapter 50 is arranged so that the positioning portions 16a, 16b of the recess 16 of the ferrule 10 butt against each other, and the positioning portions 15a, 15b of the recess 15 of the ferrule 10 abut against the elastically deforming V-shaped protrusion 54a. At this time, the V-shaped protrusion 54a receives a reaction force from the positioning portions 15a, 15b of the recess 15 and elastically deforms, and a force that causes the V-shaped protrusion 54a to return to its original position is applied to the ferrule 10. As a result, the ferrule 10 is clamped and fixed between the V-shaped protrusions 54a and 55a, and the position of the ferrule 10 relative to the adapter 50 is determined. Even with this adapter configuration, the ferrule 10 described above can be positioned relative to the adapter 50 with a simple configuration.

[0062] In the above-described embodiment and modified example, recesses 15, 16 (grooves) are formed on the side surfaces 13, 14 of the ferrule 10, and protrusions 23, 24 or V-shaped protrusions 54a, 55a are formed on the inner surfaces of the adapters 20, 50, so that the protrusions 23, 24 or V-shaped protrusions 54a, 55a fit into the recesses 15, 16. In the conventional optical connection structure 101, the ferrule 10 is positioned relative to the adapters 20 and 50 in this manner. However, as shown in Fig. 8 , conversely, in the optical connection structure 101, convex portions 115 and 116 (first and second convex portions) may be formed on the side surfaces 113 and 114 of the ferrule 110, and concave portions 154 and 155 (third and fourth concave portions) may be formed on the inner surfaces 152 and 153 of the adapter 150, so that the ferrule 110 is inserted into the adapter 150. The basic configuration of the ferrule 110, excluding the shape of the side surface, is the same as that of the ferrule 10, and detailed illustration is omitted in Fig. 8 . In this modification, the convex portion 115 formed on the side surface 113 of the ferrule 110 may be provided with two positioning portions 115a and 115b, and the convex portion 116 formed on the side surface 114 of the ferrule 110 may be provided with two positioning portions 116a and 116b. The two positioning portions 115a, 115b and the two positioning portions 116a, 116b are formed apart from each other in the longitudinal direction (Z direction, a direction perpendicular to the paper surface of FIG. 8) like the positioning portions 15a, 15b and the positioning portions 16a, 16b of the ferrule 10, and are configured to protrude slightly outward from other portions (step portions) of the side surfaces 113 and 114. Note that, as shown in FIG. 9, in the optical connection structure 101A, the convex portions 115A, 116A on the side surfaces 113A, 114A of the ferrule 110A may have a semicircular protrusion shape or an elliptical protrusion shape, and two positioning portions 117a, 117b may be provided on the side surface 113A having such a shape, and two positioning portions 118a, 118b may be provided on the side surface 114A. The two positioning portions 117a, 117b and the two positioning portions 118a, 118b are formed apart from each other in the longitudinal direction (Z direction, a direction perpendicular to the paper surface of Figure 9), similar to the positioning portions 15a, 15b and positioning portions 16a, 16b of the ferrule 10 described above, and are configured to protrude slightly outward from other portions (step portions) of the side surfaces 113A and 114A.

[0063] 10 , in the optical connection structure 201, instead of providing the protrusions 215, 216 on the side surfaces 213, 214 of the ferrule 210 with structures corresponding to the positioning portions 15a, 15b and the positioning portions 16a, 16b, two positioning portions 254a, 254b may be provided in a recess 254 formed in an inner surface 252 of the adapter 250, and two positioning portions 255a, 255b may be provided in a recess 255 formed in an inner surface 253 of the adapter 250. The two positioning portions 254a, 254b and the two positioning portions 255a, 255b are formed spaced apart from each other in the longitudinal direction (Z direction, a direction perpendicular to the plane of the paper in FIG. 10 ), similar to the positioning portions 15a, 15b and the positioning portions 16a, 16b of the ferrule 10, and are configured to protrude slightly outward from other portions of the inner surfaces 252, 253. The basic configuration of the ferrule 210, except for the side shape, is the same as that of the ferrule 10, and detailed description thereof is omitted in FIG.

[0064] 11 , in the optical connection structure 301, the positioning portions 15a, 15b and the positioning portions 16a, 16b may not be provided in the recesses 315, 316 of the side surfaces 313, 314 of the ferrule 310, but two positioning portions 354a, 354b may be provided in a protrusion 354 formed on an inner surface 352 of the adapter 350, and two positioning portions 355a, 355b may be provided in a protrusion 355 formed on an inner surface 353 of the adapter 350. The two positioning portions 354a, 354b and the two positioning portions 355a, 355b are formed spaced apart from each other in the longitudinal direction (Z direction, a direction perpendicular to the plane of the paper in FIG. 11 ), similar to the positioning portions 15a, 15b and the positioning portions 16a, 16b of the ferrule 10, and are configured to protrude slightly outward from other portions (step portions) of the inner surfaces 352, 353. The basic configuration of the ferrule 310, except for the side shape, is the same as that of the ferrule 10, and detailed description thereof is omitted in FIG.

[0065] In addition, although the present embodiment shows an example in which two positioning portions are provided on one side or inner surface, the number of positioning portions is not limited as long as there are two or more positioning portions on each side surface. For example, in any of the optical connection structures described above, three or four positioning portions may be provided on one side or inner surface. [Explanation of symbols]

[0066] 1, 51, 101, 101A, 201, 301...Optical connection structure 2...Optical connector 3...Optical fiber 4...Optical fiber ribbon 5. Boots 6…Lid part 10, 110, 110A, 210, 310...ferrules 11...Main body 11a, 11b...Window section 11c...Groove portion (optical fiber holding portion) 12...Flange 13,113,113A,213,313...Side (1st side) 14,114,114A,214,314…Side (second side) 15,315...Recess (first recess) 15a, 15b, 115a, 115b, 117a, 117b, 254a, 254b, 354a, 354b...positioning parts 15c, 15d, 15e...Stepped section 16,316...Recess (second recess) 16a, 16b, 116a, 116b, 118a, 118b, 255a, 255b, 355a, 355b...positioning parts 16c, 16d, 16e...Stepped section 17...Front end surface 18...Rear end surface 19...Lens group or through hole 20, 50, 150, 250, 350... adapter 21...Front end surface 22...Storage area 23,354...Convex part (third convex part) 24,355...Convex part (4th convex part) 25,26...Void 52, 53, 54, 55, 152, 153, 252, 253, 352, 353…Inside 54a, 55a...V-shaped protrusions (third and fourth protrusions) 54W…Wall part 56...insertion hole 61...Hollow part 115, 115A, 215... Convex portion (first convex portion) 116, 116A, 216...Convex portion (second convex portion) 154, 254...Recess (third recess) 155, 255...recess (fourth recess)

Claims

1. an optical fiber holding portion configured to hold a plurality of optical fibers; a ferrule including a first side surface and a second side surface facing each other in a second direction intersecting a first direction in which the optical fiber holding part extends, a first recess or a first protrusion extending along the first direction is provided on the first side surface, a second recess or a second protrusion extending along the first direction is provided on the second side surface, the first recess or first protrusion has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and a first step portion that is located between the first positioning portion and the second positioning portion and extends along the first direction, the first step portion is recessed toward the inside of the ferrule with respect to a surface of the first positioning portion and a surface of the second positioning portion, the second recess or second protrusion has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction, and a second step portion that is located between the third positioning portion and the fourth positioning portion and extends along the first direction, The ferrule, wherein the second step portion is recessed further inward of the ferrule than the surfaces of the third positioning portion and the fourth positioning portion.

2. the first step portion is recessed from the surfaces of the first positioning portion and the second positioning portion by a range of 0.005 mm to 2 mm.

2. The ferrule according to claim 1.

3. The first positioning portion and the second positioning portion are spaced apart from each other by a distance of 1 mm to 10 mm in the first direction. The ferrule according to claim 1 or 2.

4. the first positioning portion and the second positioning portion are formed inwardly so as to be spaced at least 0.1 mm or more from the adjacent end faces of the ferrules or the adjacent flange portions of the ferrules in the first direction. The ferrule according to any one of claims 1 to 3.

5. a width of each of the first positioning portion and the second positioning portion along the first direction is equal to or greater than 0.5 mm and equal to or less than 3 mm; The ferrule according to any one of claims 1 to 4.

6. When the first positioning portion and the second positioning portion are the first recessed portion, they have a V-shape or a U-shape in a cross section perpendicular to the first direction, and when the first positioning portion is the first convex portion, they have a semicircular protrusion shape or an elliptical protrusion shape. The ferrule according to any one of claims 1 to 5.

7. locations of the third positioning portion and the fourth positioning portion in the second recessed portion or the second protruding portion in the first direction correspond to locations of the first positioning portion and the second positioning portion in the first recessed portion or the first protruding portion in the first direction. The ferrule according to any one of claims 1 to 6.

8. further comprising a first end surface and a second end surface facing each other in the first direction, a plurality of lenses or a plurality of through holes corresponding to the plurality of optical fibers are provided on the first end surface; The second end face is provided with an opening through which the plurality of optical fibers can be inserted all at once. The ferrule according to any one of claims 1 to 7.

9. The ferrule according to any one of claims 1 to 8, a plurality of optical fibers held by the optical fiber holding portion; An optical connector comprising:

10. a plurality of optical fibers; a ferrule for holding the plurality of optical fibers; an adapter having a cylindrical shape into which the ferrule is inserted and fitted so that the ferrule and another ferrule to be connected face each other inside the cylindrical shape; Equipped with the ferrule has a first side surface and a second side surface that face each other in a second direction that intersects with a first direction in which the ferrule is inserted into the adapter; a first recess or a first protrusion extending along the first direction is provided on the first side surface, a second recess or a second protrusion extending along the first direction is provided on the second side surface, an inner surface of the adapter is provided with a third protrusion that can be fitted into the first recess or a third recess that can be fitted into the first protrusion, and a fourth protrusion that can be fitted into the second recess or a fourth recess that can be fitted into the second protrusion, the first recess or the first protrusion has a first positioning portion and a second positioning portion that are spaced apart from each other in the first direction, and a first step portion that is located between the first positioning portion and the second positioning portion and extends along the first direction, the first step portion is recessed toward the inside of the ferrule with respect to a surface of the first positioning portion and a surface of the second positioning portion, the second recess or the second protrusion has a third positioning portion and a fourth positioning portion that are spaced apart from each other in the first direction, and a second step portion that is located between the third positioning portion and the fourth positioning portion and extends along the first direction, an optical connection structure, wherein the second step portion is recessed further inward of the ferrule than the surfaces of the third positioning portion and the fourth positioning portion;

11. In a plane perpendicular to the first direction, the first positioning portion and the second positioning portion are capable of contacting the third convex portion or the third concave portion, and the third positioning portion and the fourth positioning portion are capable of contacting the fourth convex portion or the fourth concave portion. The optical connection structure according to claim 10.

12. At least one of the third convex portion or the third concave portion and the fourth convex portion or the fourth concave portion is configured to be elastically deformable in the second direction. The optical connection structure according to claim 10 or 11.

Images