JP2024166622A - Adapter and optical connection structure - Google Patents

Abstract

To provide an adapter capable of suitably maintaining optical characteristics.SOLUTION: An adapter holds a pair of ferrules facing each other in a first direction. The adapter includes a cylindrical body enclosing the pair of ferrules as seen from the first direction and forming a cylindrical shape. The cylindrical body comprises a guide that extends along the first direction and engages with side faces of the ferrules, a first slit formed from a first edge toward a second edge in the first direction, a second slit facing the first slit in a third direction and formed from a first edge toward a second edge, a third slit facing the first slit in the first direction and formed from a second edge toward a first edge, and a fourth slit facing the third slit in the third direction and formed from a second edge toward a first edge.SELECTED DRAWING: Figure 1

Description

This disclosure relates to an adapter and an optical connection structure.

Patent Document 1 discloses an optical connection structure that includes an adapter for holding a pair of opposing ferrules. In this optical connection structure, the ferrules holding multiple optical fibers are inserted into the adapter and fitted to position the multiple optical fibers.

International Publication No. 2022/085352

In the above optical connection structure, a slit is formed in the adapter along the direction in which the ferrule is inserted. In this case, when the ferrule is inserted into the adapter, the slit opens in its width direction, which can cause the wall of the adapter facing the slit to bend. This can cause a force generated by the bending of the adapter to act on the ferrule, bending the ferrule and potentially causing the optical characteristics to become unstable.

The present disclosure aims to provide an adapter and optical connection structure that can maintain good optical characteristics.

An adapter according to an embodiment of the present disclosure holds a pair of ferrules facing each other in a first direction. The adapter includes a cylindrical body that has a cylindrical shape surrounding the pair of ferrules over at least half of the circumference when viewed from the first direction. The cylindrical body includes a guide that extends along the first direction and engages with the side of the ferrule, a first slit that is formed from a first end in the first direction toward a second end opposite the first end and can be expanded in a second direction that intersects with the first direction, a second slit that faces the first slit in a third direction that intersects both the first and second directions and is formed from the first end toward the second end and can be expanded in the second direction, a third slit that faces the first slit in the first direction and is formed from the second end toward the first end and can be expanded in the second direction, and a fourth slit that faces the third slit in the third direction and is formed from the second end toward the first end and can be expanded in the second direction.

This disclosure makes it possible to maintain good optical properties.

FIG. 1 is an exploded perspective view showing an optical connection structure according to an embodiment. FIG. 2 is a cross-sectional view showing a ferrule and an optical fiber in the optical connection structure shown in FIG. FIG. 3 is a cross-sectional view showing an adapter in the optical connection structure shown in FIG. FIG. 4 is a cross-sectional view showing a schematic view of the ferrule held in the adapter shown in FIG. FIG. 5 is a perspective view showing an optical connection structure according to a first modified example. FIG. 6 is a perspective view showing an adapter in the optical connection structure shown in FIG. FIG. 7 is a cross-sectional view showing a ferrule in the optical connection structure shown in FIG. FIG. 8 is a cross-sectional view that typically shows the ferrule held in the adapter shown in FIG. FIG. 9 is a cross-sectional view showing a ferrule and an adapter in an optical connection structure according to a second modified example. FIG. 10 is a cross-sectional view showing a ferrule and an adapter in an optical connection structure according to a third modified example. FIG. 11 is a cross-sectional view showing a ferrule and an adapter in an optical connection structure according to a fourth modified example. FIG. 12 is a cross-sectional view showing a ferrule and an adapter in an optical connection structure according to a fifth modified example. FIG. 13 is a cross-sectional view showing a ferrule and an adapter in an optical connection structure according to a sixth modified example. FIG. 14 is a cross-sectional view showing a ferrule and an adapter in an optical connection structure according to a seventh modified example.

[Description of the embodiments of the present disclosure]
First, the contents of the embodiments of the present disclosure will be listed and described.
[1] An adapter according to one embodiment holds a pair of ferrules facing each other in a first direction. The adapter includes a cylindrical body that is cylindrically shaped and surrounds the pair of ferrules over at least half of the circumference when viewed from the first direction. The cylindrical body includes a guide that extends along the first direction and engages with a side surface of the ferrule, a first slit that is formed from a first end in the first direction toward a second end opposite the first end and is expandable in a second direction intersecting the first direction, a second slit that faces the first slit in a third direction intersecting both the first and second directions and is formed from the first end toward the second end and is expandable in the second direction, a third slit that faces the first slit in the first direction and is formed from the second end toward the first end and is expandable in the second direction, and a fourth slit that faces the third slit in the third direction and is formed from the second end toward the first end and is expandable in the second direction.

In this adapter, when a pair of ferrules is held inside the cylindrical body, the cylindrical body elastically deforms so that the widths of the first slit, second slit, third slit, and fourth slit become larger. In this case, the guide engages with the side of the ferrule due to a restoring force generated in the cylindrical body so that the width of the slit becomes smaller, thereby positioning the pair of ferrules when viewed from the first direction. The first slit and the second slit face each other in the third direction. Also, the third slit and the fourth slit face each other in the third direction. Therefore, when a pair of ferrules is held in the adapter, when the first slit expands in the second direction, the second slit also expands in the second direction, and when the third slit expands in the second direction, the fourth slit also expands in the second direction. Therefore, bending of the adapter is suppressed, and it is possible to maintain good optical characteristics.

[2] As one embodiment, in the above [1], the first slit and the second slit are formed over 1 mm or more from the first end toward the second end, the third slit and the fourth slit are formed over 1 mm or more from the second end toward the first end, and the first slit and the third slit, and the second slit and the fourth slit may be spaced apart by 1 mm or more in the first direction. With this configuration, the strength of the adapter can be maintained within a predetermined range.

[3] As one embodiment, in either [1] or [2] above, the cylindrical body may include a first wall in which a first slit and a third slit are formed, and a second wall facing the first wall in which a second slit and a fourth slit are formed. In the second direction, the widths of the first slit and the third slit may be 2 mm or more narrower than the width of the first wall. In the second direction, the widths of the second slit and the fourth slit may be 2 mm or more narrower than the width of the second wall. With this configuration, the strength of the adapter can be maintained within a predetermined range.

[4] An optical connection structure according to one embodiment includes an adapter according to any one of [1] to [3] and a pair of ferrules held in the cylindrical body of the adapter. With this configuration, it is possible to provide an optical connection structure having a pair of ferrules whose optical characteristics are well maintained.

[5] As one embodiment, in [4] above, the guide may have a first guide and a second guide that face each other in the second direction. Each of the pair of ferrules may have a pair of engagement portions that engage with the first guide and the second guide. In this configuration, the engagement portions of the ferrule engage with the first guide and the second guide, thereby appropriately determining the position of the ferrule when viewed from the first direction.

[6] As an embodiment, in [5] above, each of the pair of ferrules may have a first side and a second side that face each other in the third direction, and a third side and a fourth side that face each other in the second direction. The pair of engagement portions may be grooves formed in the third side and the fourth side and extending in the first direction. In this case, the first guide and the second guide can be engaged with the grooves when viewed from the first direction, thereby appropriately positioning the ferrule.

[7] As one embodiment, in the above [6], the cross-sectional shape of the groove intersecting the first direction may be V-shaped. In this configuration, when viewed from the first direction, if the tips of the first guide and the second guide each have an arc shape, the ferrule can be suitably held by the first guide and the second guide.

[8] As an embodiment, in any of [5] to [7] above, the optical connection structure may further include a pair of springs that urge the pair of ferrules in a direction facing each other, and 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.

[Details of the embodiment of the present disclosure]
Specific examples of adapters and optical connection structures according to embodiments of the present disclosure will be described below with reference to the drawings. In the following description, the same elements or elements having the same functions will be designated by the same reference numerals, and duplicated descriptions will be omitted. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

1 is an exploded perspective view showing an optical connection structure according to one embodiment. FIG. 2 is a cross-sectional view showing a ferrule in the optical connection structure shown in FIG. 1. FIG. 3 is a cross-sectional view showing an adapter in the optical connection structure shown in FIG. 1. FIG. 4 is a schematic diagram showing a ferrule held in the adapter shown in FIG. 3. As shown in FIG. 1, the optical connection structure 100 includes a pair of optical connectors 1 and an adapter 40 that holds the pair of optical connectors 1. Each of the optical connectors 1 has a plurality of optical fibers 20 (see FIG. 2), a ferrule 10 that holds the plurality of optical fibers 20, and a spring 30 that biases the ferrule 10. The rear end of the spring 30 is held by a holding member (not shown). Hereinafter, the longitudinal direction of the ferrule 10 is defined as a first direction D1, the width direction of the ferrule 10 is defined as a second direction D2, and the direction intersecting the first direction D1 and the second direction D2 is defined as a third direction D3. The first direction D1, the second direction D2, and the third direction D3 are, for example, mutually perpendicular.

1, the ferrule 10 has a substantially rectangular parallelepiped shape. The ferrule 10 has a front end 10a and a rear end 10b opposite the front end 10a in the first direction D1. The ferrule 10 has an optical end face 11 provided at the front end 10a in the first direction D1, a rear end face 12 provided at the rear end 10b in the first direction D1, and a first side face 15, a second side face 16, a third side face 13, and a fourth side face 14 extending along the first direction D1. The first side face 15 and the second side face 16 face each other in the third direction D3. The third side face 13 and the fourth side face 14 face each other in the second direction D2. The optical end face 11 faces the mating ferrule 10 (another ferrule) to be optically connected.

1 and 2, the ferrule 10 has a plurality of holding holes 18 (12 in the illustrated example) for holding a plurality of optical fibers 20. The optical fibers 20 are inserted into the holding holes 18 and held in the holding holes 18. The optical fibers 20 may be, for example, single mode fibers having a core and a clad. The holding holes 18 extend along the first direction D1. The holding holes 18 open to the optical end face 11 of the ferrule 10. The plurality of holding holes 18 are arranged side by side along the second direction D2. The 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.

2, the third side surface 13 of the ferrule 10 is provided with a first recess 23 (engagement portion, V-groove) that engages with the third protrusion 53 described later. The first recess 23 extends along the first direction D1. The first recess 23 is formed so that the cross-sectional shape along the second direction D2 and the third direction D3 at any position in the first direction D1 is uniform. For example, the cross section of the first recess 23 that intersects with the first direction D1 is V-shaped. A pair of inclined surfaces 23a, 23b that constitute the V-shaped first recess 23 open at a certain angle θ1. For example, the angle θ1 is in the range of 30° to 150°, and may be approximately 120° as an example. The bottom 23c of the groove may be subjected to R processing. The bottom 23c of the groove is a portion that connects the inclined surface 23a and the inclined surface 23b.

The fourth side surface 14 of the ferrule 10 is provided with a second recess 24 (engagement portion, V-groove) that engages with the fourth protrusion 54 described later, similar to the third side surface 13. The second recess 24 extends along the first direction D1. The second recess 24 is formed so that the cross-sectional shape along the second direction D2 and the third direction D3 at any position in the first direction D1 is uniform. For example, the cross section of the second recess 24 that intersects with the first direction D1 is V-shaped. A pair of inclined surfaces 24a, 24b that constitute the V-shaped second recess 24 are open at a certain angle θ1. The bottom portion 24c of the groove may be R-machined. The bottom portion 24c of the groove is a portion that connects the inclined surface 24a and the inclined surface 24b.

The ferrule 10 is formed, for example, from a resin. For example, the ferrule 10 is made of a material such as PEI (polyetherimide) such as Ultem (registered trademark), PPS (polyphenylene sulfide), PC (polycarbonate), PMMA (polymethyl methacrylate), or PES (polyethersulfone). The ferrule 10 is configured so that it can be inserted into and removed from the adapter 40. The ferrule 10 is inserted, for example, from the rear end 10b toward the front end 10a along the first direction D1 into the adapter 40, and is fitted into the adapter 40 (see Figures 1 and 4).

1, in the optical connection structure 100, a pair of ferrules 10 are biased by a pair of springs 30. Specifically, the spring 30 biases the ferrule 10 from the rear end 10b toward the front end 10a. As an example, the spring 30 biases the pair of ferrules 10 in the direction facing each other. A protrusion 12a for holding the end of the spring 30 from the outer periphery is formed on the rear end surface 12 of the ferrule 10. Note that the spring 30 may, for example, press the ferrule 10 along the first direction D1 while being housed in a housing or the like whose relative position with respect to the adapter 40 is determined. The magnitude of the biasing force of the spring 30 pressing the ferrule 10 is not particularly limited, but may be, for example, 10 N or less, more preferably 5 N or less.

The adapter 40 is a member that holds a pair of ferrules 10 so that the pair of ferrules 10 face each other in the first direction D1. The adapter 40 is configured with a cylindrical body 41 that extends in the first direction D1. The cylindrical body 41 has, for example, a cylindrical shape (frame shape). The cylindrical body 41 has a first end 40a in the first direction D1 and a second end 40b opposite the first end 40a. The cylindrical body 41 is configured so that the ferrule 10 can be inserted and removed from the inside of the cylindrical body 41. For example, the adapter 40 is configured so that the ferrule 10 is inserted and fitted into the cylindrical body 41 so that the ferrule 10 and another ferrule 10 face each other inside the cylindrical body 41.

The cylindrical body 41 is configured to be elastically deformable. The cylindrical body 41 is formed, for example, from a resin. The cylindrical body 41 is configured, for example, from a material such as PEI (polyetherimide) such as Ultem (registered trademark), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), PC (polycarbonate), PMMA (polymethyl methacrylate), PES (polyethersulfone), or PA (polyamide).

3 and 4, the cylindrical body 41 has a rectangular frame shape when viewed from the first direction D1, for example. The cylindrical body 41 has a first wall 45, a second wall 46, a third wall 43, and a fourth wall 44. The first wall 45 and the second wall 46 form the long sides of a rectangle when viewed from the first direction D1. The first wall 45 has a first inner peripheral surface 45a facing the first side 15 of one ferrule 10 and the second side 16 of the other ferrule 10 (see FIG. 1). The second wall 46 has a second inner peripheral surface 46a facing the second side 16 of one ferrule 10 and the first side 15 of the other ferrule 10 (see FIG. 1). The third wall 43 and the fourth wall 44 form the short sides of a rectangle when viewed from the first direction D1. The third wall 43 has a third inner peripheral surface 43a that faces the third side surface 13 of the ferrule 10. The fourth wall 44 has a fourth inner peripheral surface 44a that faces the fourth side surface 14.

The cylindrical body 41 includes a third convex portion 53 (first guide) that engages with the first concave portion 23 formed on the third side surface 13 of the ferrule 10, and a fourth convex portion 54 (second guide) that engages with the second concave portion 24 formed on the fourth side surface 14. The third convex portion 53 and the fourth convex portion 54 are formed so that the cross-sectional shapes along the second direction D2 and the third direction D3 at any position in the first direction D1 are uniform. As an example, the third convex portion 53 and the fourth convex portion 54 are formed on the third inner peripheral surface 43a and the fourth inner peripheral surface 44a, respectively. The third convex portion 53 and the fourth convex portion 54 extend in the first direction D1. The third convex portion 53 and the fourth convex portion 54 have a protrusion shape (mountain shape) that protrudes inward from the third inner peripheral surface 43a and the fourth inner peripheral surface 44a, respectively. The third convex portion 53 and the fourth convex portion 54 face each other.

The third convex portion 53 and the fourth convex portion 54 are, for example, V-shaped in a cross section intersecting the first direction D1. In the third convex portion 53, a pair of inclined surfaces 53a, 53b constituting the protrusion having an approximately V shape are connected at a constant angle θ2. Similarly, in the fourth convex portion 54, a pair of inclined surfaces 54a, 54b constituting the protrusion having an approximately V shape are connected at a constant angle θ2. The angle θ2 may be the same as the angle θ1 of the first recess 23 and the second recess 24. In addition, when viewed from the first direction D1, the respective tips 53c, 54c of the third convex portion 53 and the fourth convex portion 54 may be R-machined so as to have an arc shape. In that case, the curvature of the R machining of the tips 53c, 54c may be the same as the curvature of the R machining of the first recess 23 and the second recess 24.

When viewed from the first direction D1, the distance L1 from the tip 53c of the third convex portion 53 of the cylindrical body 41 to the tip 54c of the fourth convex portion 54 in an unloaded state is smaller than the distance L2 (see FIG. 2) from the bottom 23c of the first recess 23 of the ferrule 10 to the bottom 24c of the second recess 24. 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 pushed outward in the second direction D2. The third convex portion 53 and the fourth convex portion 54 press the third side surface 13 and the fourth side surface 14 of the ferrule 10 by the restoring force generated when the cylindrical body 41 is elastically deformed.

Here, the removal force will be specifically described. The removal force is the maximum value of the force pulling the ferrule 10 from the front end 10a to the rear end 10b when the ferrule 10 is pulled out from the adapter 40. The removal force corresponds to the lateral pressure of the ferrule 10, which is the lateral pressure on the ferrule 10 inserted and fitted into the adapter 40. In this embodiment, the lateral pressure of the ferrule 10 is the force with which the third convex portion 53 and the fourth convex portion 54 press the pair of ferrules 10. The removal force may be an index for determining the degree of interference between the ferrule 10 inserted into the adapter 40 and the adapter 40. The removal force may be 10 N or less, or 5 N or less. The removal force may also be a magnitude within the range in which the adapter 40 is elastically deformed.

The removal force is measured as follows. First, the ferrule 10 is inserted into the adapter 40. Next, the ferrule 10 is fixed, and the adapter 40 is pulled out at a constant speed. Finally, the maximum load applied when the adapter 40 is pulled out is measured, and the measured value is taken as the removal force. Note that the removal force may be measured by inserting something other than the ferrule 10 into the adapter 40. For example, the removal force may be measured by inserting an inspection gauge block into the adapter 40. As an example, the gauge block may be a metal plate. The interference amount between the gauge block inserted into the adapter 40 and the adapter 40 may be the same as the interference amount between the ferrule 10 and the adapter 40. The gauge block may have dimensions that satisfy the interference amount designed in advance, and as an example, the width of the gauge block along the second direction D2 may be the same as the distance L2 (see FIG. 2) from the bottom 23c of the first recess 23 of the ferrule 10 to the bottom 24c of the second recess 24.

The numerical range that the removal force must satisfy is described in detail below. First, the removal force is equal to or less than the biasing force of the spring 30 when the ferrule 10 is not inserted into the adapter 40 (the spring load when the connector is stored). Specifically, the removal force is equal to or less than the biasing force of the pair of springs 30 when biasing the pair of ferrules 10. For example, the removal force may be 1.5 N or less.

Next, the removal force is equal to or less than the difference between the biasing force of the spring 30 when the ferrule 10 is not inserted into the adapter 40 (hereinafter referred to as the "spring load when the connector is stored") and the biasing force of the spring 30 when the ferrule 10 is inserted into the adapter 40 and butted against another ferrule 10 (hereinafter referred to as the "spring load when the ferrule is back"). For example, the removal force may be 1.8 N or less.

The ferrule 10 is stored in the housing (not shown) of the optical connector 1 while the spring 30 is contracted along the first direction D1. The biasing force of the spring 30 in this case is the spring load when the connector is stored. When the ferrule 10 is inserted into the adapter 40 and butted against another ferrule 10, the ferrule 10 and the other ferrule 10 press against each other along the first direction D1. At this time, the ferrule 10 is pressed by the other ferrule 10, causing the spring 30 to further contract along the first direction D1. The biasing force of the spring 30 in this case is the spring load when the ferrule is backed up. Furthermore, the value of the spring load when the connector is stored and the value of the spring load when the ferrule is backed up are the minimum values of the numerical ranges calculated based on the dimensions of each part of the optical connector 1. At this time, the biasing force when the spring 30 is compressed to a specified dimension is measured as the spring load when the connector is stored and the spring load when the ferrule is backed up, respectively.

Finally, the extraction force is equal to or greater than the load of the spring 30 required for the optical characteristics to be stable when the ferrule 10 is repeatedly attached to and detached from the adapter 40. Specifically, the extraction force is equal to or greater than the load of the spring 30 required for three times the standard deviation (3σ) of the fluctuation value of the connection loss to be 0.1 dB or less when the ferrule 10 is repeatedly attached to and detached from the adapter 40. For example, the extraction force may be 0.7 N or greater. In this case, the lateral pressure on the ferrule 10 inserted and fitted into the adapter 40 becomes sufficiently large, making it possible to maintain good optical characteristics. For example, even when the ferrule 10 is repeatedly attached to and detached from the adapter 40, the deterioration of the positioning accuracy of the multiple optical fibers 20 is suppressed, making it possible to maintain good optical characteristics. The load of the spring 30 required for the optical characteristics to be stable when the ferrule 10 is repeatedly attached to and detached from the adapter 40 is calculated based on an actually measured value. The load of the spring 30 may be 1% or more and 15% or less of the spring load value preset at the time of design.

An example of the numerical range that the pulling force should satisfy will be described. The case will be described where the material of the ferrule 10 and the adapter 40 is Ultem, and the spring load preset at the time of design is 5.0N±0.5N. In this case, the spring load when the connector is stored is 1.4N. The difference between the spring load when the ferrule is back and the spring load when the connector is stored is 1.8N. The load of the spring 30 required to stabilize the optical characteristics when the ferrule 10 is repeatedly attached to and detached from the adapter 40 is 0.1N or more and 0.7N or less. The pulling force is equal to or more than the load of the spring 30 required to stabilize the optical characteristics when the ferrule 10 is repeatedly attached to and detached from the adapter 40, equal to or less than the spring load when the connector is stored, and equal to or less than the difference between the spring load when the ferrule is back and the spring load when the connector is stored. From the above, the pulling force is equal to or more than 0.1N and 1.4N or less. In this case, the pulling force becomes moderate, and it is possible to easily pull out the ferrule 10 from the adapter 40. As a result, user convenience is improved.

The cylindrical body will be described again. The cylindrical body 41 has a plurality of slits so that when the ferrule 10 is inserted, the cylindrical body 41 is slightly expanded to press the ferrule 10. For example, the cylindrical body 41 in the illustrated example has a first slit 42A, a second slit 42B, a third slit 42C, and a fourth slit 42D. The first slit 42A is formed from the first end 40a to the second end 40b in the first direction D1. The first slit 42A can be expanded slightly in the second direction D2 when a force is applied to the cylindrical body 41 to expand it in the second direction D2. In the illustrated example, the first slit 42A is formed from the first end 40a of the first wall body 45 toward the second end 40b along the first direction D1. The first slit 42A is formed to a position closer to the first end 40a than the center of the first direction D1. The first slit 42A is formed at the center of the first wall 45 in the second direction D2.

The second slit 42B is formed from the first end 40a to the second end 40b in the first direction D1. The second slit 42B can be slightly expanded in the second direction D2 when a force is applied to the cylindrical body 41 to expand it in the second direction D2. In the illustrated example, the second slit 42B is formed from the first end 40a of the second wall body 46 toward the second end 40b along the first direction D1. The second slit 42B is formed to a position closer to the first end 40a than the center in the first direction D1. The second slit 42B is formed at the center of the second wall body 46 in the second direction D2. Therefore, the second slit 42B faces the first slit 42A in the third direction D3.

The third slit 42C is formed from the second end 40b toward the first end 40a in the first direction D1. When a force is applied to the cylindrical body 41 to push it open in the second direction D2, the third slit 42C can be slightly expanded in the second direction D2. In the illustrated example, the third slit 42C is formed from the second end 40b of the first wall body 45 toward the first end 40a along the first direction D1. The third slit 42C is formed to a position closer to the second end 40b than the center in the first direction D1. The third slit 42C is formed at the center of the first wall body 45 in the second direction D2. Therefore, the third slit 42C faces the first slit 42A in the first direction D1.

The fourth slit 42D is formed from the second end 40b toward the first end 40a in the first direction D1. When a force is applied to the cylindrical body 41 to push it open in the second direction D2, the fourth slit 42D can be slightly expanded in the second direction D2. In the illustrated example, the fourth slit 42D is formed from the second end 40b of the second wall body 46 toward the first end 40a along the first direction D1. The fourth slit 42D is formed to a position closer to the second end 40b than the center in the first direction D1. The fourth slit 42D is formed at the center of the second wall body 46 in the second direction D2. Therefore, the fourth slit 42D faces the third slit 42C in the third direction D3 and faces the second slit 42B in the first direction D1.

As shown in FIG. 1, the first slit 42A and the third slit 42C are spaced apart from each other in the first direction D1, and the second slit 42B and the fourth slit 42D are spaced apart from each other in the first direction D1. As a result, the first wall 45 has a first portion 45A connected to the fourth wall 44, a second portion 45B connected to the third wall 43, and a third portion 45C connecting the first portion 45A and the second portion 45B at the center of the first direction D1. Similarly, the second wall 46 has a first portion 46A connected to the fourth wall 44, a second portion 46B connected to the third wall 43, and a third portion 46C connecting the first portion 46A and the second portion 46B at the center of the first direction D1.

The first slit 42A and the second slit 42B may be formed over 1 mm or more from the first end 40a toward the second end 40b. Similarly, the third slit 42C and the fourth slit 42D may be formed over 1 mm or more from the second end 40b toward the first end 40a. The interval between the first slit 42A and the third slit 42C and the interval between the second slit 42B and the fourth slit 42D are 1 mm or more apart in the first direction D1. The interval between the first slit 42A and the third slit 42C is the length of the third portion 46C in the first direction D1, and the interval between the second slit 42B and the fourth slit 42D is the length of the third portion 46C in the first direction D1. In the second direction D2, the width of the first slit 42A and the third slit 42C is 2 mm or more narrower than the width of the first wall body 45. That is, the length of the first portion 45A and the second portion 45B in the second direction D2 may each be 1 mm or more. In the second direction D2, the width of the second slit 42B and the fourth slit 42D is 2 mm or more narrower than the width of the second wall 46. That is, the length of the first portion 46A and the second portion 46B in the second direction D2 may each be 1 mm or more.

The first slit 42A, the second slit 42B, the third slit 42C, and the fourth slit 42D may have the same length in the first direction D1 and the same width in the second direction D2. The first slit 42A, the second slit 42B, the third slit 42C, and the fourth slit 42D may not have a width in the second direction D2 in the unloaded state. That is, in the unloaded state, the first portion 45A and the second portion 45B may be in contact with each other, and the first portion 46A and the second portion 46B may be in contact with each other.

As described above, the adapter 40 holds a pair of ferrules 10 facing each other in the first direction D1. The adapter 40 has a cylindrical body 41 that has a cylindrical shape that surrounds the pair of ferrules 10 over at least half of the circumference when viewed from the first direction D1. The cylindrical body 41 includes a third convex portion 53 and a fourth convex portion 54 that extend along the first direction D1 and engage with the third side surface 13 and the fourth side surface 14 of the ferrule 10, a first slit 42A that is formed from the first end 40a to the second end 40b in the first direction D1 and can be expanded in the second direction D2, a second slit 42B that faces the first slit 42A in the third direction D3, is formed from the first end 40a to the second end 40b, and can be expanded in the second direction D2, a third slit 42C that faces the first slit 42A in the first direction D1, is formed from the second end 40b to the first end 40a, and can be expanded in the second direction D2, and a fourth slit 42D that faces the third slit 42C in the third direction D3, is formed from the second end 40b to the first end 40a, and can be expanded in the second direction D2.

In this adapter 40, when a pair of ferrules 10 are held inside the cylindrical body 41, the cylindrical body 41 elastically deforms so that the widths of the first slit 42A, the second slit 42B, the third slit 42C, and the fourth slit 42D increase. In this case, the third convex portion 53 and the fourth convex portion 54 engage with the third side surface 13 and the fourth side surface 14 of the ferrule 10 due to the restoring force generated in the cylindrical body 41 so that the width of the slits decreases, thereby positioning the pair of ferrules 10 when viewed from the first direction D1. The first slit 42A and the second slit 42B face each other in the third direction D3. Also, the third slit 42C and the fourth slit 42D face each other in the third direction D3. Therefore, when the pair of ferrules 10 are held in the adapter 40, when the first slit 42A expands in the second direction D2, the second slit 42B also expands in the second direction D2, and when the third slit 42C expands in the second direction D2, the fourth slit 42D also expands in the second direction D2. Therefore, bending of the adapter 40 is suppressed, and it is possible to maintain good optical characteristics.

The first slit 42A and the second slit 42B are formed over 1 mm or more from the first end 40a toward the second end 40b, the third slit 42C and the fourth slit 42D are formed over 1 mm or more from the second end 40b toward the first end 40a, and the first slit 42A and the third slit 42C, and the second slit 42B and the fourth slit 42D may be spaced apart by 1 mm or more in the first direction D1. With this configuration, the strength of the adapter 40 can be maintained within a predetermined range.

In the second direction D2, the width of the first slit 42A and the third slit 42C may be 2 mm or more narrower than the width of the first wall 45. In the second direction D2, the width of the second slit 42B and the fourth slit 42D may be 2 mm or more narrower than the width of the second wall 46. In this configuration, the strength of the adapter 40 can be maintained within a predetermined range.

The optical connection structure 100 includes an adapter 40 and a pair of ferrules 10 held in the cylindrical body 41 of the adapter 40. With this configuration, it is possible to provide an optical connection structure 100 having a pair of ferrules 10 whose optical characteristics are well maintained.

Each of the pair of ferrules 10 may have a first recess 23 and a second recess 24 that engage with the third protrusion 53 and the fourth protrusion 54, respectively. In this configuration, the first recess 23 and the second recess 24 of the ferrule 10 engage with the third protrusion 53 and the fourth protrusion 54, thereby appropriately determining the position of the ferrule 10 when viewed from the first direction D1.

The first recess 23 and the second recess 24 may be grooves formed on the third side surface 13 and the fourth side surface 14 and extending in the first direction D1. In this case, the third protrusion 53 and the fourth protrusion 54 engage with the grooves when viewed from the first direction D1, thereby allowing the ferrule 10 to be appropriately positioned.

The cross-sectional shape of the first recess 23 and the second recess 24 intersecting the first direction D1 may be V-shaped. In this configuration, when viewed from the first direction D1, if the tips of the third convex portion 53 and the fourth convex portion 54 each have an arc shape, the third convex portion 53 and the fourth convex portion 54 can suitably hold the ferrule 10.

The optical connection structure 100 includes a pair of springs 30 that urge the pair of ferrules 10 in the opposing directions, and the force with which the third convex portion 53 and the fourth convex portion 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 ferrule 10 held in the adapter 40 can be moved in the first direction D1 by the spring load. In other words, the pair of ferrules 10 that are facing each other can be pressed against each other.

The optical connection structure and adapter according to the present disclosure have been described in detail above, but the present invention is not limited to the above embodiment and can be applied to various embodiments and modifications.

A first modified example of the optical connection structure according to the present disclosure will be described. FIG. 5 is a perspective view showing the optical connection structure of the first modified example. FIG. 6 is a perspective view showing an adapter of the first modified example. FIG. 7 is a diagram showing the cross-sectional shape of the ferrule of the first modified example. FIG. 8 is a diagram showing a schematic view of the ferrule shown in FIG. 7 being held in the adapter shown in FIG. 6.

As shown in FIG. 5, 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, the pair of ferrules 10 are biased inward by a pair of springs 30, as in the above embodiment. In the first modified example, the numerical range that the extraction force must satisfy is the same as in the above embodiment. For example, the extraction force is 0.7 N or more. In the second to seventh modified examples, the numerical range that the extraction force must satisfy is the same as in the above embodiment.

The adapter 140 holds a pair of ferrules 10 so that they face each other. The adapter 140 includes a cylindrical body 141 extending in the first direction D1. As shown in FIG. 6, the cylindrical body 141 has, for example, a rectangular frame shape when viewed from the first direction D1. That is, the adapter 140 has a first wall 145, a second wall 146, a third wall 143, and a fourth wall 144, as shown in FIG. 6. The first wall 145 and the second wall 146 form the long sides of a rectangle when viewed from the first direction D1. The first wall 145 has a first inner surface 145a facing the first side surface 15. The second wall 146 has a second inner surface 146a facing the second side surface 16. The third wall 143 and the fourth wall 144 form the short sides of a rectangle when viewed from the first direction D1. The third wall 143 has a third inner peripheral surface 143a that faces the third side surface 13 of the ferrule 10. The fourth wall 144 has a fourth inner peripheral surface 144a that faces the fourth side surface 14.

The cylindrical body 141 according to the first modification has a plurality of slits so that it is easily elastically deformed when the ferrule 10 is inserted, as in the above-described embodiment. That is, the cylindrical body 141 has a first slit 142A formed from the first end 140a of the first wall body 145 toward the second end 140b along the first direction D1, a second slit 142B formed from the first end 140a of the second wall body 146 toward the second end 140b along the first direction D1, a third slit 142C formed from the second end 140b of the first wall body 145 toward the first end 140a along the first direction D1, and a fourth slit 142D formed from the second end 140b of the second wall body 146 toward the first end 140a along the first direction D1. The shapes (configurations) of the first slit 142A, the second slit 142B, the third slit 142C, and the fourth slit 142D may be similar to the shapes (configurations) of the first slit 42A, the second slit 42B, the third slit 42C, and the fourth slit 42D in the above-described embodiment.

The cylindrical body 141 includes a third convex portion 153 that fits into the first recess 23 of the ferrule 10, and a fourth convex portion 154 that fits into the second recess 24. The third convex portion 153 and the fourth convex portion 154 are formed so that the cross-sectional shapes along the second direction D2 and the third direction D3 at any position in the first direction D1 are uniform. As an example, the third convex portion 153 and the fourth convex portion 154 are formed on the third inner peripheral surface 143a and the fourth inner peripheral surface 144a, respectively, by the third wall body 143 and the fourth wall body 144 curving inward. The third convex portion 153 and the fourth convex portion 154 extend in the first direction D1. The cylindrical body 141 is formed of an elastically deformable resin, as in the above embodiment.

When viewed from the first direction D1, the third convex portion 153 and the fourth convex portion 154 have an arc shape that protrudes inward from the third inner circumferential surface 143a and the fourth inner circumferential surface 144a, respectively. The third convex portion 153 and the fourth convex portion 154 face each other. In this example, the curvatures of the third convex portion 153 and the fourth convex portion 154 that form the arc shape are equal to each other. In other words, the imaginary circle S that is tangent to the arc-shaped portion of the third inner circumferential surface 143a and the imaginary circle S that is tangent to the arc-shaped portion of the fourth inner circumferential surface 144a have the same diameter. As an example, the radius of this imaginary circle S may be about 0.2 mm to 2.0 mm.

In the unloaded state, the distance L3 (see FIG. 6) from the center of the virtual circle S tangent to the arc-shaped portion of the third inner peripheral surface 143a to the center of the virtual circle S tangent to the arc-shaped portion of the fourth inner peripheral surface 144a is smaller than the distance L4 (see FIG. 7) from the center of the virtual circle S tangent to the first recess 23 to the center of the virtual circle S tangent to the second recess 24. The diameter of the virtual circle S tangent to the third side surface 13 and the fourth side surface 14 is the same as the diameter of the virtual circle S tangent to the third inner peripheral surface 143a and the fourth inner peripheral surface 144a. When the ferrule 10 is held in the cylindrical body 141 of the adapter 140, the cylindrical body 141 is elastically deformed so as to be expanded in the second direction D2. The third convex portion 153 and the fourth convex portion 154 press the third side surface 13 and the fourth side surface 14 of the ferrule 10 by the restoring force when the cylindrical body 141 is elastically deformed.

In the above embodiment, the third side surface 13 and the fourth side surface 14 of the ferrule 10 are provided with the first recess 23 and the second recess 24, respectively, and the third inner circumferential surface 43a and the fourth inner circumferential surface 44a of the adapter 40 are provided with the third convex portion 53 and the fourth convex portion 54, respectively, but this is not limited to the above. Figures 9 to 14 are diagrams for explaining the optical connection structures of the second to seventh modified examples. Figures 9 to 14 show cross-sectional views of the adapter and ferrule as viewed from the first direction D1. Note that only the essential parts are depicted in these figures, and for example, the first and second walls of the adapter are not depicted.

9, in the second modified example, the third side surface 13 and the fourth side surface 14 of the ferrule 10 may be provided with a first convex portion 223 and a second convex portion 224, respectively, and the third inner peripheral surface 43a and the fourth inner peripheral surface 44a of the adapter 40 may be provided with a third recess 253 and a fourth recess 254, respectively. The cross-sectional shape of the first convex portion 223 of the ferrule in a direction intersecting the first direction D1 is V-shaped. When viewed from the first direction D1, the apex 223a of the V-shaped first convex portion 223 protrudes outward in the second direction D2. In addition, the cross-sectional shape of the third recess 253 of the adapter in a direction intersecting the first direction D1 is V-shaped with an angle equal to the angle θ3 of the apex 223a of the first convex portion 223.

The cross-sectional shape of the second convex portion 224 of the ferrule in a direction intersecting the first direction D1 is V-shaped. When viewed from the first direction D1, the apex 224a of the V-shaped second convex portion 224 protrudes outward in the second direction D2. In addition, the cross-sectional shape of the fourth recess 254 of the adapter in a direction intersecting the first direction D1 is a V-shape that opens at an angle equal to the angle θ3 of the apex 224a of the second convex portion 224.

As shown in FIG. 10, in the third modified example, the third side surface 13 and the fourth side surface 14 of the ferrule 10 may be provided with a first recess 323 and a second protrusion 324, respectively, and the third inner circumferential surface 43a and the fourth inner circumferential surface 44a of the adapter 40 may be provided with a third protrusion 353 and a fourth recess 354, respectively. The cross-sectional shape of the first recess 323 in a direction intersecting the first direction D1 is V-shaped. When viewed from the first direction D1, the bottom 323a of the V-shaped first recess 323 is recessed toward the inside in the second direction D2. The cross-sectional shape of the third protrusion 353 in a direction intersecting the first direction D1 is V-shaped with a top 353a having an angle equal to the angle θ4 of the bottom 323a of the first recess 323.

The cross-sectional shape of the second convex portion 324 in a direction intersecting the first direction D1 is V-shaped. When viewed from the first direction D1, the apex 324a of the V-shaped second convex portion 324 protrudes outward in the second direction D2. The cross-sectional shape of the fourth recess 354 in a direction intersecting the first direction D1 is a V-shape that opens at an angle equal to the angle θ5 of the apex 324a of the second convex portion 324.

For example, as shown in FIG. 11, in the fourth modified example, the third side surface 13 and the fourth side surface 14 of the ferrule 10 may be provided with a first convex portion 423 and a second convex portion 424, respectively, and the third inner peripheral surface 43a and the fourth inner peripheral surface 44a of the adapter 40 may be provided with a third concave portion 453 and a fourth concave portion 454, respectively. The first convex portion 423 and the second convex portion 424 may protrude outward in the second direction D2, and the third concave portion 453 and the fourth concave portion 454 may be formed in a groove shape so as to correspond to the first convex portion 423 and the second convex portion 424, respectively. The cross-sectional shape of the first convex portion 423 and the second convex portion 424 in the direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. When viewed from the first direction D1, the first convex portion 423 and the second convex portion 424 protrude toward the outside in the second direction D2. In addition, the cross-sectional shape of the third recess 453 in a direction intersecting the first direction D1 has a U-shape curved with the same curvature as the first convex portion 423. The cross-sectional shape of the fourth recess 454 in a direction intersecting the first direction D1 has a U-shape curved with the same curvature as the second convex portion 424.

For example, as shown in FIG. 12, in the fifth modified example, the third side surface 13 and the fourth side surface 14 of the ferrule 10 may have a first recess 523 and a second recess 524, respectively, and the third inner peripheral surface 43a and the fourth inner peripheral surface 44a of the adapter 40 may have a third convex portion 553 and a fourth convex portion 554, respectively. The first recess 523 and the second recess 524 may be formed in a groove shape, and the third convex portion 553 and the fourth convex portion 554 may be recessed toward the inside in the second direction D2 so as to correspond to the first recess 523 and the second recess 524, respectively. The cross-sectional shape of the first recess 523 and the second recess 524 in the direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. In addition, the cross-sectional shape of the third convex portion 553 in the direction intersecting the first direction D1 has a U-shape curved with the same curvature as the curvature of the first recess 523. The cross-sectional shape of the fourth convex portion 554 in the direction intersecting the first direction D1 has a U-shape that is curved with the same curvature as the second concave portion 524.

For example, as shown in FIG. 13, in the sixth modified example, the third side surface 13 and the fourth side surface 14 of the ferrule 10 may be provided with a first convex portion 623 and a second concave portion 624, respectively, and the third inner peripheral surface 43a and the fourth inner peripheral surface 44a of the adapter 40 may be provided with a third concave portion 653 and a fourth convex portion 654, respectively. The first convex portion 623 may protrude outward in the second direction D2, and the third concave portion 653 may be formed in a groove shape so as to correspond to the first convex portion 623. The second concave portion 624 may be formed in a groove shape, and the fourth convex portion 654 may protrude inward in the second direction D2 so as to correspond to the second concave portion 624. The cross-sectional shape of the first convex portion 623 and the second concave portion 624 in the direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. In addition, the cross-sectional shape of the third concave portion 653 in the direction intersecting the first direction D1 has a U-shape curved with the same curvature as the curvature of the first convex portion 623. The cross-sectional shape of the fourth convex portion 654 in a direction intersecting the first direction D1 has a U-shape that is curved with the same curvature as the second concave portion 624.

14, in the seventh modification, the third side surface 13 and the fourth side surface 14 of the ferrule 10 may be provided with a first convex portion 723 and a second convex portion 724, respectively, and the third inner peripheral surface 43a and the fourth inner peripheral surface 44a of the adapter 40 may be provided with a third recessed portion 753 and a fourth recessed portion 754, respectively. The first convex portion 723 and the second convex portion 724 may protrude outward in the second direction, and the third recessed portion 753 and the fourth recessed portion 754 may be formed in a groove shape so as to correspond to the first convex portion 723 and the second convex portion 724, respectively. The cross-sectional shape of the first convex portion 723 and the second convex portion 724 in the direction intersecting the first direction D1 is a U-shape curved with a predetermined curvature. When viewed from the first direction D1, the first convex portion 723 and the second convex portion 724 protrude toward the outside in the second direction D2. Additionally, the cross-sectional shape of the third recess 753 and the fourth recess 754 in a direction intersecting the first direction D1 has a V-shape that opens at a predetermined angle.

The adapter 40 does not have to be entirely made of resin, as long as a portion of it is made of an elastic material such as resin and is therefore elastically deformable.

In the above embodiment, the cylindrical body 41 constituting the adapter 40 has a cylindrical shape when viewed from the first direction D1, but the shape of the cylindrical body is not limited to this. The cylindrical body may be substantially cylindrical, and may have a wall formed over at least half a circumference around an axis along the first direction D1 when viewed from the first direction D1. For example, the cylindrical body 41 in the above embodiment may not have the third portion 45C of the first wall body 45, and the first wall body 45 may be formed only by the first portion 45A and the second portion 45B. In this embodiment, the first slit 42A and the third slit 42C are connected to each other, so that a single slit is formed in the first wall body 45 from the first end 40a to the second end 40b. Although such a cylindrical body does not form a complete cylindrical shape (annular shape) when viewed from the first direction D1, the shape of the cylindrical body is also defined as a cylindrical shape in this specification. In this way, if either of the third portions 45C and 46C is not present, the ferrule is held by the cylindrical body with less force.

1...optical connector 10...ferrule 10a...front end 10b...rear end 11...optical end face 12...rear end face 12a...projection 13...third side face 14...fourth side face 15...first side face 16...second side face 17...opening 18...retaining hole 20...optical fiber 23...first recess (engagement portion)
23a...inclined surface 23b...inclined surface 23c...bottom portion 24...second recess (engagement portion)
24a...inclined surface 24b...inclined surface 24c...bottom 30...spring 40...adapter 40a...first end 40b...second end 41...cylindrical body 42A...first slit 42B...second slit 42C...third slit 42D...fourth slit 43...third wall body 43a...third inner circumferential surface 44...fourth wall body 44a...fourth inner circumferential surface 45...first wall body 45a...first inner circumferential surface 45A...first portion 45B...second portion 45C...third portion 46...second wall body 46A...first portion 46B...second portion 46C...third portion 46a...second inner circumferential surface 53...third convex portion (first guide)
53a...inclined surface 53b...inclined surface 53c...tip 54...fourth convex portion (second guide)
54a...inclined surface 54b...inclined surface 54c...tip 100...optical connection structure 101...optical connection structure 140...adapter 140a...first end 140b...second end 141...cylindrical body 142A...first slit 142B...second slit 142C...third slit 142D...fourth slit 143...third wall body 143a...third inner circumferential surface 144...fourth wall body 144a...fourth inner circumferential surface 145...first wall body 145a...first inner circumferential surface 146...second wall body 146a...second inner circumferential surface 153...third convex portion 154...fourth convex portion 223...first convex portion 223a...vertex 224...second convex portion 224a...vertex 253...third recess 254...fourth recess 323 ...First recess 323a...Bottom 324...Second convex portion 324a...Vertex 353...Third convex portion 353a...Top 354...Fourth recess 423...First convex portion 424...Second convex portion 453...Third concave portion 454...Fourth recess 523...First recess 524...Second recess 553...Third convex portion 554...Fourth convex portion 623...First convex portion 624...Second recess 653...Third concave portion 654...Fourth convex portion 723...First convex portion 724...Second convex portion 753...Third concave portion 754...Fourth recess D1...First direction D2...Second direction D3...Third direction L1...Distance L2...Distance L3...Distance L4...Distance S...Virtual circle θ1...Angle θ2...Angle θ3...Angle θ4...Angle θ5...Angle

Claims (8)

An adapter for holding a pair of ferrules facing each other in a first direction,
a cylindrical body surrounding the pair of ferrules over at least half a circumference when viewed from the first direction,
The cylindrical body is
a guide extending along the first direction and engaging with a side surface of the ferrule;
a first slit formed from a first end in the first direction toward a second end opposite to the first end and expandable in a second direction intersecting the first direction;
a second slit that faces the first slit in a third direction intersecting both the first direction and the second direction, is formed from the first end toward the second end, and is expandable in the second direction;
a third slit that faces the first slit in the first direction, is formed from the second end toward the first end, and is expandable in the second direction;
an adapter comprising: a fourth slit that faces the third slit in the third direction, is formed from the second end toward the first end, and is expandable in the second direction. The first slit and the second slit are formed over a distance of 1 mm or more from the first end toward the second end,
The third slit and the fourth slit are formed over a distance of 1 mm or more from the second end toward the first end,
The adapter according to claim 1 , wherein the first slit and the third slit, and the second slit and the fourth slit are spaced apart by 1 mm or more in the first direction. The cylindrical body is
a first wall body in which the first slit and the third slit are formed;
a second wall facing the first wall and having the second slit and the fourth slit formed therein;
In the second direction, the widths of the first slit and the third slit are narrower than the width of the first wall by 2 mm or more,
The adapter according to claim 1 or 2, wherein a width of the second slit and the fourth slit in the second direction is narrower than a width of the second wall by 2 mm or more. An adapter according to claim 1;
the pair of ferrules held in the cylindrical body of the adapter. The guide includes a first guide and a second guide facing each other in the second direction,
The optical connection structure according to claim 4 , wherein each of the pair of ferrules has a pair of engagement portions that engage with the first guide and the second guide. each of the pair of ferrules includes a first side surface and a second side surface opposed to each other in the third direction, and a third side surface and a fourth side surface opposed to each other in the second direction;
The optical connection structure according to claim 5 , wherein the pair of engagement portions are grooves formed on the third side surface and the fourth side surface and extending in the first direction. The optical connection structure according to claim 6, wherein the cross-sectional shape of the groove intersecting the first direction is V-shaped. A pair of springs are further provided to bias the pair of ferrules in directions opposite to each other,
8. The optical connection structure according to claim 5, wherein a force with which the first guide and the second guide press against the pair of ferrules is smaller than a spring load with which the pair of springs urge the pair of ferrules.

Images