Optical connection structure

Abstract

An adapter including a tubular body that, with a line along a first direction as an axis, forms a tube shape that surrounds a pair of ferrules across at least half the circumference thereof, said tubular body comprising a guide that extends in the first direction and engages with a ferrule lateral surface, and a slit formed from one end to an other end in the first direction.

Description

[Technical Field]

[0001] The present disclosure relates to an adapter and an optical connection structure. [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 a ferrule, and the other end of the pair of guide pins is inserted into a pair of guide pin insertion holes provided in a mating ferrule. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-90974 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned technology, a guide pin with high dimensional accuracy is used to minimize the clearance with respect to the guide pin insertion hole, and therefore, if the guide pin is inserted and removed multiple times, the guide pin insertion hole may be damaged, which may reduce the positioning accuracy.

[0005] An object of the present disclosure is to provide an adapter and an optical connection structure that are capable of positioning a plurality of optical fibers with a simple configuration. [Means for solving the problem]

[0006] An adapter according to one embodiment of the present disclosure holds a pair of opposing ferrules. The adapter includes a cylindrical body that surrounds the pair of ferrules over at least halfway around a line extending in a first direction. The cylindrical body includes a guide that extends in the first direction and engages with a side surface of the ferrule, and a slit that is formed from one end to the other end in the first direction. [Effects of the Invention]

[0007] According to the adapter and optical connection structure of the present disclosure, it is possible to position a plurality of optical fibers with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an exploded perspective view showing an example of an optical connection structure. [Figure 2] FIG. 2 is a diagram showing a cross-sectional shape of an example ferrule. [Figure 3] FIG. 3 is a diagram showing a cross-sectional shape of an example adapter. [Figure 4] FIG. 4 is a diagram schematically illustrating a ferrule held in an adapter. [Figure 5] FIG. 5 is a perspective view showing another example of an optical connection structure. [Figure 6] FIG. 6 is a diagram showing a cross-sectional shape of another example of an adapter. [Figure 7] FIG. 7 is a diagram showing a cross-sectional shape of another example of a ferrule. [Figure 8] FIG. 8 is a diagram schematically illustrating a state in which the ferrule of FIG. 7 is held in the adapter of FIG. [Figure 9] FIG. 9 is a schematic diagram for explaining still another optical connection structure. [Figure 10] FIG. 10 is a schematic diagram for explaining still another optical connection structure. [Figure 11] FIG. 11 is a schematic diagram for explaining still another optical connection structure. [Figure 12] FIG. 12 is a schematic diagram for explaining still another optical connection structure. [Figure 13] FIG. 13 is a schematic diagram for explaining still another optical connection structure. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. An adapter according to one embodiment of the present disclosure holds a pair of ferrules facing each other. The adapter includes a cylindrical body that surrounds the pair of ferrules over at least halfway around a line along a first direction. The cylindrical body includes a guide that extends in the first direction and engages with a side surface of the ferrule, and a slit formed from one end to the other end in the first direction.

[0010] An optical connection structure according to an embodiment of the present disclosure includes the above adapter and a pair of ferrules held by the cylindrical body of the adapter.

[0011] This adapter has a cylindrical body with a slit formed from one end to the other end, and is elastically deformable. Therefore, for example, when the cylindrical body is elastically deformed so that the width of the slit increases, a restoring force may be generated in the cylindrical body so that the width of the slit decreases. In the above adapter, when a pair of ferrules is held inside the cylindrical body, the guide engages with the side surfaces of the ferrules, so that the positions of the pair of ferrules when viewed from the first direction are determined. Therefore, according to one embodiment of the adapter, multiple optical fibers can be positioned with a simple configuration without using guide pins. Note that when a slit is formed in the cylindrical body, the cylindrical body does not actually have a cylindrical shape, but in this specification, a shape that surrounds the ferrule over more than half of its circumference is defined as a cylindrical shape.

[0012] The cylindrical body may be made of resin, which can prevent damage to the ferrule.

[0013] The guide may include a first guide extending in the first direction and engaging with a side surface of the ferrule, and a second guide extending in the first direction and engaging with a side surface of the ferrule. In this configuration, when the pair of ferrules are held inside the cylindrical body, the first guide and the second guide each separately engage with a side surface of the ferrule, so the positions of the pair of ferrules when viewed from the first direction can be determined more accurately.

[0014] The first guide and the second guide may protrude inward from the inner circumferential surface of the cylindrical body. In this configuration, groove-shaped engaging portions corresponding to the first guide and the second guide are formed on the first side surface and the second side surface of the ferrule, so that the first guide can engage with the first side surface and the second guide can engage with the second side surface.

[0015] When viewed from the first direction, each of the first guide and the second guide may have an arc shape. With this configuration, when V-grooves corresponding to the first guide and the second guide are formed on the first side surface and the second side surface of the ferrule, the ferrule can be suitably held by the first guide and the second guide.

[0016] When viewed from the first direction, the cylindrical body has a substantially rectangular frame shape, and the first guide and the second guide may be respectively provided on a pair of walls that define the short sides of the rectangle when viewed from the first direction. In this configuration, the distance between the first guide and the second guide can be made large, thereby suppressing wobble in the rotational direction of the ferrule with its axial direction being the first direction.

[0017] Each of the pair of ferrules may have an engagement portion that engages with the first guide and the second guide, and the engagement portion of the ferrule engages with the first guide and the second guide, thereby determining the position of the ferrule when viewed from the first direction.

[0018] Each of the pair of ferrules may have a first side surface and a second side surface that face each other in a second direction that intersects the first direction. In this case, the engagement portion may be a groove formed in the first side surface and the second side surface and extending in the first direction. In this case, the first guide and the second guide may protrude from the inner circumferential surface of the cylindrical body so as to be engageable with the groove when viewed from the first direction.

[0019] The cross-sectional shape of the groove intersecting the first direction may be V-shaped. When the tip ends of the first guide and the second guide have an arc shape when viewed from the first direction, the ferrule can be suitably held by the first guide and the second guide.

[0020] The optical connection structure may further include a pair of springs that urge the pair of ferrules toward each other. The force with which the first guide and the second guide press the pair of ferrules may be smaller than the spring load with which the pair of springs urge the pair of ferrules. In this configuration, the ferrules held in the adapter can be moved in the first direction by the spring load. In other words, the pair of ferrules facing each other can be pressed against each other.

[0021] [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. In the following description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0022] FIG. 1 is an exploded perspective view showing an example optical connection structure. FIG. 2 is a diagram showing a cross-sectional shape of an example ferrule. FIG. 3 is a diagram showing a cross-sectional shape of an example adapter. FIG. 4 is a diagram schematically showing a ferrule held in an adapter. An example optical connection structure 1 includes a pair of ferrules 10 and an adapter 40 that holds the pair of ferrules 10. The pair of ferrules 10 have the same shape. The ferrule 10 has a substantially rectangular parallelepiped shape and has an optical end face 11 provided at one end in a first direction D1, a rear end face 12 provided at the other end in the first direction D1, and a first side face 13, a second side face 14, a third side face 15, and a fourth side face 16 extending along the first direction D1. The optical end face 11 can face the mating ferrule 10 to be optically connected.

[0023] The first side surface 13 and the second side surface 14 face each other in a second direction D2 that intersects with the first direction D1. The third side surface 15 and the fourth side surface 16 face each other in a third direction D3 that intersects with both the first direction D1 and the second direction D2. The first direction D1, the second direction D2, and the third direction D3 are, for example, perpendicular to each other.

[0024] The ferrule 10 has a plurality (twelve in the illustrated example) of optical fiber holding holes (optical fiber holding portions) 18 for holding a plurality of optical fibers. The optical fibers are inserted into and held in the optical fiber holding holes 18. The optical fibers may be, for example, single-mode fibers having a core and a cladding. The optical fiber holding holes 18 extend along a first direction D1. The optical fiber holding holes 18 open to the optical end face 11 of the ferrule 10. The plurality of optical fiber holding holes 18 are arranged side by side along a second direction D2. The optical fiber holding holes 18 also communicate with an opening 17 for inserting an optical fiber ribbon. The opening 17 is formed in the rear end face 12.

[0025] The ferrule 10 has an engagement portion 23 that engages with a first guide 53 and a second guide 54 (described later). The engagement portion 23 is formed so that its cross-sectional shape along the second direction D2 and the third direction D3 at any position in the first direction D1 is uniform. An example of the engagement portion 23 may be a groove formed on each of the first side surface 13 and the second side surface 14 and extending in the first direction D1. In the illustrated example, the cross-sectional shape of the engagement portion 23 intersecting the first direction D1 is V-shaped. A pair of inclined surfaces 23a, 23b constituting the V-shaped groove open at a constant angle θ1. For example, the angle θ1 is in the range of 30° to 150°, and may be approximately 120°, for example. The bottom 23c of the groove may be rounded. The bottom 23c of the groove connects the inclined surfaces 23a and 23b.

[0026] The ferrule 10 is made of a material such as PPS (polyphenylene sulfide), PEI (polyetherimide), PC (polycarbonate), PMMA (polymethyl methacrylate), or PES (polyethersulfone), etc. The ferrule 10 is inserted into the adapter 40 along the first direction D1, for example, and fitted to the adapter 40.

[0027] In the optical connection structure 1 of the present disclosure, a pair of ferrules 10 are biased by a pair of springs 30. In one example, the springs 30 bias the pair of ferrules 10 in directions facing each other. A protrusion 12a is formed on the rear end surface 12 of the ferrule 10 to hold the end of the spring 30 from the outer periphery. Note that the spring 30 may press the ferrule 10 along the first direction D1 while being housed in, for example, a housing or the like whose position relative to the adapter 40 is determined. The magnitude of the spring load of the spring 30 pressing the ferrule 10 is not particularly limited, but may be, for example, 10 N or less, and more preferably 5 N or less.

[0028] The adapter 40 holds a pair of ferrules 10 facing each other. The adapter 40 includes a cylindrical body 41 extending in the first direction D1 and has a slit 42 formed from one end to the other in the first direction D1. The cylindrical body 41 may be substantially cylindrical, and may have a wall surface formed over at least half a circumference around an assumed axis when viewed from one direction. An example adapter 40 surrounds at least a pair of ferrules 10 over at least half a circumference around an axis that is aligned with the first direction D1.

[0029] In the illustrated example, the cylindrical body 41 has a substantially rectangular frame shape when viewed from the first direction D1. That is, the cylindrical body 41 has a first wall 43, a second wall 44, a third wall 45, and a fourth wall 46. The first wall 43 and the second wall 44 form the short sides of the rectangle when viewed from the first direction D1. The first wall 43 has a first inner circumferential surface 43a facing the first side surface 13 of the ferrule 10. The second wall 44 has a second inner circumferential surface 44a facing the second side surface 14. The third wall 45 has a third inner circumferential surface 45a facing the third side surface 15 of one ferrule 10 and the fourth side surface 16 of the other ferrule 10. The fourth wall 46 has a fourth inner circumferential surface 46a facing the fourth side surface 16 of the one ferrule 10 and the third side surface 15 of the other ferrule 10.

[0030] In the illustrated example, a slit 42 is formed in the third wall 45 that forms the third inner circumferential surface 45a. The slit 42 is provided along the first direction D1. The slit 42 separates the third wall 45 into one side and the other side in the second direction D2. In the illustrated example, the slit 42 is depicted with a predetermined width in the second direction D2, but, for example, the slit 42 may not have a width in the unloaded state. That is, in the unloaded state, the third wall 45 on one side and the third wall 45 on the other side in the second direction D2 may abut against each other. Furthermore, for example, the slit 42 may be formed across the entire third wall 45 in the second direction D2.

[0031] The cylindrical body 41 includes a first guide 53 that engages with the engaging portion 23 formed on the first side surface 13 of the ferrule 10, and a second guide 54 that engages with the engaging portion 23 formed on the second side surface 14. The first guide 53 and the second guide 54 are formed so that their cross-sectional shapes along the second direction D2 and the third direction D3 at any position in the first direction D1 are uniform. In one example, the first guide 53 and the second guide 54 are formed on the first inner circumferential surface 43a and the second inner circumferential surface 44a, respectively. The first guide 53 and the second guide 54 extend in the first direction D1. In the illustrated example, the first guide 53 and the second guide 54 have a protrusion shape that protrudes inward from the first inner circumferential surface 43a and the second inner circumferential surface 44a, respectively. The first guide 53 and the second guide 54 face each other.

[0032] The cross-sectional shapes of the first guide 53 and the second guide 54 intersecting the first direction D1 are generally V-shaped. In the first guide 53, a pair of inclined surfaces 53a, 53b constituting the generally V-shaped protrusion are connected at a constant angle θ2. Similarly, in the second guide 54, a pair of inclined surfaces 54a, 54b constituting the generally V-shaped protrusion are connected at a constant angle θ2. The angle θ2 may be the same as the angle θ1 of the engagement portion 23. Note that, when viewed from the first direction D1, the respective tips 53c, 54c of the first guide 53 and the second guide 54 may be rounded to have an arc shape. In this case, the curvature of the rounded tip 53c, 54c may be the same as the curvature of the rounded tip 53c, 54c of the engagement portion 23.

[0033] When viewed from the first direction D1, the distance L1 from the tip 53c of the first guide 53 of the cylindrical body 41 to the tip 54c of the second guide 54 in an unloaded state is smaller than the distance L2 from the bottom 23c of the engaging portion 23 on the first side surface 13 of the ferrule 10 to the bottom 23c of the engaging portion 23 on the second side surface 14. When the ferrule 10 is held in the cylindrical body 41 of the adapter 40, the cylindrical body 41 elastically deforms so as to be expanded in the second direction D2. The first guide 53 and the second guide 54 press the first side surface 13 and the second side surface 14 of the ferrule 10 by a restoring force generated when the cylindrical body 41 is elastically deformed. The force with which the first guide 53 and the second guide 54 press the pair of ferrules 10 is smaller than the spring load with which the pair of springs 30 urge the pair of ferrules 10.

[0034] The cylindrical body 41 is made of an elastically deformable resin, such as PEI (polyetherimide), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), PC (polycarbonate), PMMA (polymethyl methacrylate), PES (polyethersulfone), or PA (polyamide).

[0035] As described above, the adapter 40 according to an embodiment of the present disclosure holds a pair of ferrules 10 that face each other and are optically connected. Each of the pair of ferrules 10 includes a plurality of optical fiber holding holes 18 for holding a plurality of optical fibers, and a first side surface 13 and a second side surface 14 that face each other along a second direction D2 that intersects with a first direction D1 in which the plurality of optical fiber holding holes 18 extend. The adapter 40 includes an elastically deformable cylindrical body 41. The cylindrical body 41 surrounds the pair of ferrules 10 over at least halfway around its axis, which is aligned with a line along the first direction D1. The cylindrical body 41 includes a first guide 53 extending in the first direction D1 and engaging with the first side surface 13, a second guide 54 extending in the first direction D1 and engaging with the second side surface 14, and a slit 42 formed from one end to the other end in the first direction D1, and the first guide 53 and the second guide 54 press the first side surface 13 and the second side surface 14 together due to the restoring force of elastic deformation.

[0036] The adapter 40 has a cylindrical body 41 with a slit 42 formed from one end to the other end, and is elastically deformable. Therefore, for example, when the cylindrical body 41 elastically deforms so that the width of the slit 42 increases, a restoring force is generated in the cylindrical body 41 so that the width of the slit 42 decreases. When a ferrule 10 is to be held in the adapter 40, the ferrule 10 is inserted from the end of the adapter 40 in the first direction D1. In the adapter 40 described above, with a pair of ferrules 10 held inside the cylindrical body 41, the restoring force of the elastic deformation of the cylindrical body 41 causes the first guide 53 and the second guide 54 to press against the first side surface 13 and the second side surface 14. Each of the pair of ferrules 10 may have an engaging portion 23 that engages with the first guide 53 and the second guide 54. In this case, the first guide 53 engages with the first side surface 13, and the second guide 54 engages with the second side surface 14, so the positions of the pair of ferrules 10 are determined when viewed from the first direction D1. As described above, the adapter 40 according to one embodiment allows multiple optical fibers to be positioned with a simple configuration without using guide pins.

[0037] The first guide 53 and the second guide 54 may protrude inward from the inner circumferential surface of the cylindrical body 41. Furthermore, the engagement portion 23 may be a groove formed in the first side surface 13 and the second side surface 14, extending in the first direction D1. In this configuration, the first guide 53 can engage with the engagement portion 23 of the first side surface 13, and the second guide 54 can engage with the engagement portion 23 of the second side surface 14.

[0038] When viewed from the first direction D1, the cylindrical body 41 has a substantially rectangular frame shape, and the first guide 53 and the second guide 54 may be provided on the first wall 43 and the second wall 44, respectively, which form the shorter sides of the rectangle of the cylindrical body 41 when viewed from the first direction D1. In this configuration, the distance between the first guide 53 and the second guide 54 can be made large, thereby suppressing wobble in the rotational direction of the ferrule 10 whose axial direction is the first direction D1.

[0039] The cylindrical body 41 may be made of resin. In this configuration, the engagement portion 23 of the ferrule 10 is prevented from being damaged by the first guide 53 and the second guide 54.

[0040] The optical connection structure 1 may include a pair of springs 30 that urge the pair of ferrules 10 in directions facing each other. The force with which the first guide 53 and the second guide 54 press the pair of ferrules 10 may be smaller than the spring load with which the pair of springs 30 urge the pair of ferrules 10. In this configuration, the pair of ferrules 10 held in the adapter 40 can be pressed against each other by the spring load.

[0041] Even if the cylindrical body 41 does not have the third wall 45, i.e., if the entire third wall is formed as the slit 42, it is possible for the pair of engaging portions 23 of the ferrule 10 to be pressed by the first guide 53 and the second guide 54. However, as in the above example, the formation of the third wall 45 makes it difficult for the ferrule 10 held in the adapter 40 to be exposed to the outside of the adapter 40. In other words, the ferrule 10 is protected from the outside by the adapter 40.

[0042] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the claims.

[0043] An optical connection structure having an adapter according to another example will be described below. Fig. 5 is a perspective view showing an optical connection structure according to another example. Fig. 6 is a perspective view showing the optical connection structure according to another example. adapter 7 is a diagram showing the cross-sectional shape of another example. ferrule FIG. 8 is a diagram showing the cross-sectional shape of FIG. 6 The adapter in the diagram 7 10 is a diagram showing a state in which the ferrule is held. FIG.

[0044] The optical connection structure 101 includes a pair of ferrules 10 and an adapter 140 that holds the pair of ferrules 10. Although not shown in FIG. 5 , in the optical connection structure 101 as well, the pair of ferrules 10 may be biased by a pair of springs 30.

[0045] The adapter 140 holds a pair of opposing ferrules 10. The adapter 140 includes a cylindrical body 141 extending in a first direction D1 and has a slit 142 formed from one end to the other in the first direction D1. In the illustrated example, the cylindrical body 141 has a substantially rectangular frame shape when viewed from the first direction D1. That is, the adapter 140 has a first wall 143, a second wall 144, a third wall 145, and a fourth wall 146. The first wall 143 and the second wall 144 form the short sides of the rectangle when viewed from the first direction D1. The first wall 143 has a first inner circumferential surface 143a facing the first side surface 13 of the ferrule 10. The second wall 144 has a second inner circumferential surface 144a facing the second side surface 14. The third wall 145 has a third inner circumferential surface 145a facing the third side surface 15. The fourth wall 146 has a fourth inner circumferential surface 146a facing the fourth side surface 16. In the illustrated example, a slit 142 is formed in the third wall 145 that forms the third inner circumferential surface 145a.

[0046] The cylindrical body 141 includes a first guide 153 that engages with the first side surface 13 of the ferrule 10 and a second guide 154 that engages with the second side surface 14. The first guide 153 and the second guide 154 are formed so that their cross-sectional shapes along the second direction D2 and the third direction D3 at any position in the first direction D1 are uniform. In one example, the first guide 153 and the second guide 154 are formed on the first inner circumferential surface 143a and the second inner circumferential surface 144a, respectively, by the first wall body 143 and the second wall body 144 curving inward. The first guide 153 and the second guide 154 extend in the first direction D1.

[0047] In the illustrated example, the first guide 153 and the second guide 154 have an arc shape that protrudes inward from the first inner circumferential surface 143a and the second inner circumferential surface 144a, respectively, when viewed from the first direction D1. The first guide 153 and the second guide 154 face each other. In this example, the curvatures of the arc-shaped first guide 153 and the second guide 154 are equal to each other. That is, the imaginary circle S tangent to the arc-shaped portion of the first inner circumferential surface 143a and the imaginary circle S tangent to the arc-shaped portion of the second inner circumferential surface 144a have the same diameter. As an example, the radius of this imaginary circle S may be approximately 0.2 mm to 2.0 mm.

[0048] In an unloaded state, a distance L3 (see FIG. 6) from the center of an imaginary circle S tangent to the arc-shaped portion of the first inner circumferential surface 143a to the center of an imaginary circle S tangent to the arc-shaped portion of the second inner circumferential surface 144a is smaller than a distance L4 (see FIG. 7) from the center of the imaginary circle S tangent to the engaging portion 23 of the first side surface 13 of the ferrule 10 to the center of the imaginary circle S tangent to the engaging portion 23 of the second side surface 14. The diameter of the imaginary circle S tangent to the first side surface 13 and the second side surface 14 is the same as the diameter of the imaginary circle S tangent to the first inner circumferential surface 143a and the second inner circumferential surface 144a. When the ferrule 10 is held in the cylindrical body 141 of the adapter 140, the cylindrical body 141 elastically deforms so as to be expanded in the second direction D2. The first guide 153 and the second guide 154 press the first side surface 13 and the second side surface 14 of the ferrule 10 by a restoring force when the cylindrical body 141 is elastically deformed. The force with which the first guide 153 and the second guide 154 press the pair of ferrules 10 is smaller than the spring load with which the pair of springs 30 urge the pair of ferrules 10.

[0049] The cylindrical body 141 is formed of an elastically deformable resin, such as PEI (polyetherimide), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), PC (polycarbonate), PMMA (polymethyl methacrylate), PES (polyethersulfone), or PA (polyamide).

[0050] According to the adapter 140 of this other example, similar to the adapter 40 of the example of FIG. 1, etc., it is possible to position a plurality of optical fibers with a simple configuration without using guide pins.

[0051] Furthermore, when viewed from the first direction D1, the first guide 153 and the second guide 154 each have an arc shape. The cross section of the engagement portion 23 intersecting the first direction D1 is V-shaped. This configuration allows for variations in the angles of the tips of the first guide 153 and the second guide 154. The first guide 153 and the second guide 154 position the ferrule 10 by making line contact with the left and right inclined surfaces 23a, 23b that constitute the V-groove-shaped engagement portion 23 of the ferrule 10. When the cylindrical body 141 is expanded, the angle at which the tips of the first guide 153 and the second guide 154 face each other varies slightly from a position where they face each other to a position where they face the third inner circumferential surface 145a. However, since the first guide 153 and the second guide 154 are arc-shaped when viewed from the first direction D1, even if there is a deviation in the angle of the tip, they can make line contact with the engaging portion 23 of the ferrule 10 in the same way as when there is no deviation.

[0052] Furthermore, the shapes of the engaging portion 23 provided on the ferrule 10 and the first guide 153 and second guide 154 provided on the adapter 140 are not limited to those of the above-described examples. Figures 9 to 13 are schematic diagrams for explaining still other optical connection structures. When viewed from the first direction D1, Figures 9 to 13 schematically show modified examples of how the engaging portion of the ferrule engages with the guides (first guide, second guide) of the adapter. Note that these figures only depict essential parts, and do not depict, for example, the third and fourth walls of the adapter.

[0053] 9, the engaging portion 223 of the ferrule may protrude outward in the second direction D2, and the guide 253 of the adapter may be formed in a groove shape to correspond to the engaging portion 223. In the illustrated example, the cross-sectional shape of the engaging portion 223 of the ferrule in the direction intersecting the first direction D1 is V-shaped. When viewed from the first direction D1, the apex 223a of the V-shaped engaging portion 223 protrudes outward in the second direction D2. Furthermore, the cross-sectional shape of the guide 253 of the adapter in the direction intersecting the first direction D1 is V-shaped with an angle equal to the angle θ3 of the apex 223a of the engaging portion 223.

[0054] As shown in FIG. 10, the shapes of the pair of engaging portions may be different from each other, and the shapes of the pair of guides may be different from each other. In the illustrated example, one engaging portion 323A of the ferrule has a V-shaped cross section in a direction intersecting the first direction D1. When viewed from the first direction D1, a bottom 323Aa of the V-shaped engaging portion 323A is recessed inward in the second direction D2. The other engaging portion 323B of the ferrule also has a V-shaped cross section in a direction intersecting the first direction D1. When viewed from the first direction D1, an apex 323Ba of the V-shaped engaging portion 323B protrudes outward in the second direction D2. The cross section of one guide 353 of the adapter in a direction intersecting the first direction D1 is V-shaped with an apex 353a at an angle equal to the angle θ4 of the bottom 323Aa of the engaging portion 323A. The cross section of the other guide 354 of the adapter in a direction intersecting the first direction D1 is V-shaped with an angle equal to the angle θ5 of the apex 323Ba of the engaging portion 323B.

[0055] 11, the engaging portion 423 of the ferrule may protrude outward in the second direction, and the guide of the adapter may be formed in a groove shape to correspond to the engaging portion. In the illustrated example, the cross-sectional shape of the engaging portion 423 of the ferrule in a direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. When viewed from the first direction D1, the engaging portion 423 protrudes outward in the second direction D2. Furthermore, the cross-sectional shape of the guide 453 of the adapter in a direction intersecting the first direction is a U-shape curved with the same curvature as the engaging portion 423.

[0056] 12, the engaging portion 523 of the ferrule may be formed in a groove shape, and the guide of the adapter may protrude inward in the second direction to correspond to the engaging portion. In the illustrated example, the cross-sectional shape of the engaging portion 523 of the ferrule in a direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. Also, the cross-sectional shape of the guide 553 of the adapter in a direction intersecting the first direction is a U-shape curved with the same curvature as the engaging portion.

[0057] 13, the engaging portion of the ferrule may protrude outward in the second direction, and the guide of the adapter may be formed in a groove shape to correspond to the engaging portion. In the illustrated example, the cross-sectional shape of the engaging portion 623 of the ferrule in a direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. When viewed from the first direction D1, the engaging portion 623 protrudes outward in the second direction D2. Furthermore, the cross-sectional shape of the guide 653 of the adapter in a direction intersecting the first direction D1 is a V-shape opened at a predetermined angle.

[0058] Furthermore, in each of the above embodiments, the configurations of the other embodiments can be reused or added to, as long as there are no particular contradictions or problems.

[0059] The adapter does not have to be made entirely of an elastic material, but may be made partially of an elastic material so as to be elastically deformable. [Explanation of symbols]

[0060] 1...Optical connection structure 10...Ferrule 11...Optical end face 12...Rear end surface 12a...Protrusion 13…First side 14…Second side 15…Third side 16…Fourth side 17...Aperture 18...Optical fiber holding hole (optical fiber holding portion) 23...Engagement portion 23a...slope 23b…Slope 23c...Bottom 30...Spring 40...Adapter 41...Cylindrical body 42...Slit 43…1st wall body 43a...First inner peripheral surface 44...Second wall 44a…Second inner peripheral surface 45…Third wall body 45a…Third inner peripheral surface 46…4th wall body 46a...Fourth inner peripheral surface 53...First Guide 53a...slope 53b...slope 53c...tip 54...Second Guide 54a...slope 54b...slope 54c…Tip 101...Optical connection structure 140...Adapter 141...Cylindrical body 142...Slit 143…1st wall body 143a...First inner peripheral surface 144...Second wall 144a...Second inner peripheral surface 145…Third wall body 145a...Third inner peripheral surface 146…4th wall body 146a...Fourth inner peripheral surface 153...First Guide 154...Second Guide 223...Engagement portion 223a...Vertex 253... Guide 323A…Engagement part 323Aa…Bottom 323B…Engagement part 323Ba…vertex 353... Guide 353a...top 354... Guide 423...Engagement part 453... Guide 523...Engagement part 553... Guide 623...Engagement part 653... Guide D1…first direction D2…Second direction D3…Third direction L1~L4…distance S...imaginary circle θ1~θ5…Angle

Claims

1. a pair of ferrules arranged so that their optical end faces face each other; an adapter for holding the pair of ferrules facing each other; a pair of springs that urge the pair of ferrules held by the adapter in directions facing each other, the adapter includes a cylindrical body having a cylindrical shape that surrounds the pair of ferrules over at least half a circumference with a line extending in a first direction as an axis, The cylindrical body is a guide extending in the first direction and engaging with a side surface of the ferrule; a slit formed from one end to the other end in the first direction, the guide includes a first guide extending in the first direction and engaging with a side surface of the ferrule, and a second guide extending in the first direction and engaging with a side surface of the ferrule, When viewed from the first direction, the cylindrical body has a substantially rectangular frame shape, the first guide and the second guide are respectively provided on a pair of walls that define shorter sides of the rectangular cylindrical body when viewed from the first direction, the first guide and the second guide are formed from one end to the other end of the cylindrical body in the first direction, the first guide and the second guide have a first end in the first direction and a second end opposite to the first end, and have the same shape from the first end to the second end; Each of the ferrules has a pair of protrusions protruding along the first direction on a rear end face, which is an end face opposite to the optical end face, The pair of protrusions are provided on both ends of the rear end surface in a second direction intersecting the first direction, and hold the spring.

2. The optical connection structure according to claim 1 , wherein the cylindrical body is made of resin.

3. The optical connection structure according to claim 1 , wherein the first guide and the second guide protrude inward from an inner circumferential surface of the cylindrical body.

4. The optical connection structure according to claim 1 , wherein the first guide and the second guide each have an arc shape when viewed from the first direction.

5. 5. The optical connection structure according to claim 1, wherein each of the pair of ferrules has an engaging portion that engages with the first guide and the second guide.

6. each of the pair of ferrules includes a first side surface and a second side surface facing each other in the second direction; The optical connection structure according to claim 5 , wherein the engagement portion is a groove formed on the first side surface and the second side surface and extending in the first direction.

7. The optical connection structure according to claim 6 , wherein the cross section of the groove intersecting the first direction is V-shaped.

8. 8. The optical connection structure according to claim 1, wherein the force with which the first guide and the second guide press against the pair of ferrules is smaller than the spring load with which the pair of springs urge the pair of ferrules.

9. The optical connection structure according to claim 1 , wherein the slit has no width in the second direction when no external load is applied.

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