JP2024118801A - Optical connection structure, optical connector, and adapter - Google Patents

Abstract

To provide: an optical connection structure capable of excellently maintaining optical properties; an optical connector; and an adapter.SOLUTION: An optical connection structure includes an optical connector and an adapter. The optical connector includes a plurality of optical fibers, a ferrule for holding the plurality of optical fibers, and a spring for energizing the ferrule. The adapter is constituted so that the optical connector is inserted and fitted so as to face the ferrule to the other ferrules in the cylindrical inside. The ferrule has first and second side surfaces facing each other. The first side surface has a first depression or a first projection, and the second side surface has a second depression or a second projection. The inner surface of the adapter has a third projection or a third depression and a fourth projection or a fourth depression. When extracting the ferrule from the adapter, the maximum extraction force extracting the ferrule from the front end toward the rear end is 0.7 N or more.SELECTED DRAWING: Figure 1

Description

This disclosure relates to optical connection structures, optical connectors, and adapters.

Patent Document 1 and Patent Document 2 disclose optical connection structures that include an adapter for holding a pair of opposing ferrules. In these optical connection structures, the ferrules holding multiple optical fibers are inserted into the adapter and fitted to position the multiple optical fibers.

International Publication No. 2022/085352 International Publication No. 2021/192746

In the optical connection structures described in Patent Documents 1 and 2, if the lateral pressure on the ferrule inserted and fitted into the adapter is too small, the optical characteristics may deteriorate. For example, when the ferrule is repeatedly attached to and detached from the adapter, the positioning accuracy of the multiple optical fibers may deteriorate, causing the optical characteristics to become unstable.

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

An optical connection structure according to an embodiment of the present disclosure includes an optical connector having a plurality of optical fibers, a ferrule that holds the plurality of optical fibers and has a front end and a rear end opposite the front end, a spring that biases the ferrule from the rear end to the front end, and an adapter that has a cylindrical shape and is configured to insert and engage the optical connector so that the ferrule and another ferrule face each other inside the cylindrical shape, the ferrule has a first side surface and a second side surface that face each other, the first side surface is provided with a first concave portion or a first convex portion that extends along a first direction in which the optical connector is inserted into the adapter, the second side surface is provided with a second concave portion or a second convex portion that extends along the first direction, the inner surface of the adapter is provided with a third convex portion or a third concave portion that can be engaged with the first concave portion or the first convex portion, and a fourth convex portion or a fourth concave portion that can be engaged with the second concave portion or the second convex portion, and a removal force that is the maximum force that pulls the ferrule from the front end to the rear end when pulling the ferrule out of the adapter is 0.7 N or more.

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 cross-sectional 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 optical connection structure according to one embodiment includes an optical connector having a plurality of optical fibers, a ferrule that holds the plurality of optical fibers and has a front end and a rear end opposite the front end, and a spring that biases the ferrule from the rear end to the front end, and an adapter having a cylindrical shape and configured to insert and engage with the optical connector so that the ferrule and another ferrule face each other inside the cylindrical shape, the ferrule having a first side and a second side that face each other, the first side having a first concave portion or a first convex portion that extends along a first direction in which the optical connector is inserted into the adapter, the second side having a second concave portion or a second convex portion that extends along the first direction, an inner surface of the adapter having a third convex portion or a third concave portion that can be engaged with the first concave portion or the first convex portion, and a pull-out force that is the maximum force that pulls the ferrule from the front end to the rear end when pulling the ferrule out of the adapter is 0.7 N or more.

In this optical connection structure, the maximum force that pulls the ferrule from the front end to the rear end when pulling the ferrule out of the adapter is 0.7 N or more. With this configuration, the lateral pressure on the ferrule inserted and fitted into the adapter is sufficiently large, making it possible to maintain good optical characteristics. For example, even if the ferrule is repeatedly attached and detached from the adapter, deterioration of the positioning accuracy of the multiple optical fibers is suppressed, making it possible to maintain good optical characteristics.

[2] As one embodiment, in the above [1], the removal force may be equal to or less than the difference between the spring force when the optical connector is not inserted into the adapter and the spring force when the optical connector is inserted into the adapter and butted against another ferrule. Conventionally, if the lateral pressure on the ferrule inserted and mated into the adapter is too large, it may be difficult to remove the ferrule from the adapter. However, according to the configuration of the present disclosure, the removal force is of an appropriate magnitude, making it possible to easily remove the ferrule from the adapter. As a result, user convenience is improved.

[3] As an embodiment, in either [1] or [2] above, the adapter may be made of resin and have a slit formed in the first direction from a first end to a second end opposite the first end. In this case, when a ferrule is inserted into the adapter, the adapter may elastically deform so that the width of the slit increases, and a restoring force may be generated in the adapter so that the width of the slit decreases. This may generate lateral pressure on the ferrule inserted into the adapter. As a result, it is possible to position multiple optical fibers with a simple configuration without using guide pins or the like.

[4] As an embodiment, in any of [1] to [3] above, a first recess and a second recess are provided on the first side and the second side, respectively, a third convex portion and a fourth convex portion are provided on the inner surface of the adapter, and the first recess and the second recess are each V-shaped in a cross section intersecting the first direction, and the third convex portion and the fourth convex portion may each be V-shaped in a cross section intersecting the first direction. In this case, the ferrule can be positioned with high precision relative to the adapter. In other words, the positioning of multiple optical fibers can be performed with high precision.

[5] An optical connector according to one embodiment includes a plurality of optical fibers, a ferrule that holds the plurality of optical fibers and has a front end and a rear end opposite the front end, and a spring that biases the ferrule from the rear end toward the front end, the ferrule is configured to be insertable into and removable from a cylindrical adapter, and has a first side and a second side that face each other, the first side has a first recess or a first protrusion that extends along a first direction in which the ferrule is inserted into the adapter, and the second side has a second recess or a second protrusion that extends along the first direction, and the removal force, which is the maximum force that pulls the ferrule from the front end toward the rear end when the ferrule is pulled out of the adapter, is 0.7 N or more.

In this optical connector, the maximum force required to pull the ferrule from the front end to the rear end when removing the ferrule from the adapter is 0.7 N or more. With this configuration, the lateral pressure on the ferrule inserted and mated into the adapter is sufficiently large. As a result, an optical connection structure that can maintain good optical characteristics can be realized.

[6] As one embodiment, in the above [5], the removal force may be equal to or less than the difference between the spring force when the ferrule is not inserted into the adapter and the spring force when the ferrule is inserted into the adapter and butted against another ferrule. In this case, the removal force is of an appropriate magnitude, making it possible to easily pull the ferrule out of the adapter. As a result, user convenience is improved.

[7] In one embodiment, a cylindrical body is provided that has a cylindrical shape and is configured so that a ferrule can be inserted and removed inside the cylindrical shape, and a third convex portion or a third concave portion and a fourth convex portion or a fourth concave portion are provided on the inner surface of the cylindrical body, and the removal force, which is the maximum force that pulls the ferrule from the front end to the rear end when pulling the ferrule out of the cylindrical body, is 0.7 N or more.

In this adapter, the maximum force required to pull the ferrule from the front end to the rear end when removing the ferrule from the adapter is 0.7 N or more. With this configuration, the lateral pressure on the ferrule inserted and mated into the adapter is sufficiently large. As a result, an optical connection structure capable of maintaining good optical characteristics can be realized.

[8] In one embodiment, in the above [7], the removal force may be 1.4 N or less. In this case, the removal force is of an appropriate magnitude, making it possible to easily pull the ferrule out of the adapter. As a result, user convenience is improved.

[Details of the embodiment of the present disclosure]
Specific examples of optical connection structures, optical connectors, and adapters 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 13, a second side face 14, a third side face 15, and a fourth side face 16 extending along the first direction D1. The first side face 13 and the second side face 14 face each other in the second direction D2. The third side face 15 and the fourth side face 16 face each other in the third direction D3. 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 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 first side surface 13 of the ferrule 10 is provided with a first recess 23 that engages with a 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 first recess 23 is V-shaped in a cross section intersecting the first direction D1. 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 R-machined. The bottom 23c of the groove is a portion that connects the inclined surface 23a and the inclined surface 23b.

The second side surface 14 of the ferrule 10 is provided with a second recess 24 that engages with a fourth protrusion 54, which will be described later, in the same manner as the first 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 second recess 24 is V-shaped in a cross section intersecting the first direction D1. A pair of inclined surfaces 24a, 24b that constitute the V-shaped second recess 24 are open at a certain angle θ1. The bottom 24c of the groove may be rounded. The bottom 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 to be insertable into and removable from the adapter 40. The ferrule 10 is inserted into the adapter 40 along the first direction D1 from the rear end 10b to the front end 10a, for example, 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 they face each other. The adapter 40 includes a cylindrical body 41 extending in the first direction D1. The adapter 40 has a first end 40a and a second end 40b opposite to the first end 40a. The adapter 40 has a slit 42 formed from the first end 40a to the second end 40b in the first direction D1. The cylindrical body 41 has, for example, a cylindrical shape. The cylindrical body 41 is configured so that the ferrule 10 can be inserted and removed from the inside of the cylindrical shape. 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. Note that the cylindrical body 41 only needs to be substantially cylindrical, and when viewed from one direction, it is sufficient that a wall surface is formed over about half a circumference or more around the assumed axis. As an example, the adapter 40 surrounds at least one pair of ferrules 10 over more than half a circumference, with the axis being a line along the first direction D1.

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 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 a rectangle when viewed from the first direction D1. The first wall 43 has a first inner peripheral surface 43a (inner surface) facing the first side surface 13 of the ferrule 10. The second wall 44 has a second inner peripheral surface 44a (inner surface) facing the second side surface 14. The third wall 45 has a third inner peripheral surface 45a facing the third side surface 15 of one ferrule 10 and the fourth side surface 16 of the other ferrule 10 (see FIG. 1). The fourth wall 46 has a fourth inner peripheral surface 46a that faces the fourth side surface 16 of one ferrule 10 and the third side surface 15 of the other ferrule 10 (see FIG. 1).

The cylindrical body 41 is configured to be slightly expanded when the ferrule 10 is inserted, and to press the ferrule 10. Specifically, 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 is a notch provided in the third wall 45, and separates the third wall 45 into a first portion 45A and a second portion 45B. The first portion 45A and the second portion 45B extend from the first end 40a to the second end 40b along the first direction D1 (see FIG. 1). This allows the adapter 40 to be uniformly deformed in the first direction D1 when the ferrule 10 is inserted.

The first portion 45A and the second portion 45B are aligned in the second direction D2. As an example, the slit 42 has a predetermined width in the second direction D2, but is not limited to this. For example, the slit 42 may not have a width in an unloaded state. That is, in an unloaded state, the first portion 45A and the second portion 45B may abut against each other. Also, for example, the slit 42 may be formed so that the widths of the first portion 45A and the second portion 45B in the second direction D2 are each 1 mm or more. In this case, an extreme decrease in strength of the adapter 40 caused by the widths of the first portion 45A and the second portion 45B in the second direction D2 being 0 mm is suppressed.

The cylindrical body 41 includes a third convex portion 53 that fits (corresponds) to the first recess 23 formed on the first side surface 13 of the ferrule 10, and a fourth convex portion 54 that fits (corresponds) to the second recess 24 formed on the second 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 first inner peripheral surface 43a and the second 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 first inner peripheral surface 43a and the second inner peripheral surface 44a, respectively. The third convex portion 53 and the fourth convex portion 54 face each other.

For example, the third convex portion 53 and the fourth convex portion 54 are each 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 first side surface 13 and the second 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 amount of interference between the gauge block inserted into the adapter 40 and the adapter 40 may be the same as the amount of interference between the ferrule 10 and the adapter 40. The gauge block may have dimensions that satisfy the amount of interference 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 backed"). 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. 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 10% to 15% of the spring load value preset at the time of design.

An example of the numerical range that the extraction 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 0.5N or more and 0.7N or less. The extraction 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 extraction force is equal to or more than 0.7N and equal to or less than 1.4N.

The effects of the optical connection structure 100, optical connector 1, and adapter 40 according to this embodiment are described below. In the optical connection structure 100 according to this embodiment, the maximum force pulling the ferrule 10 from the front end 10a to the rear end 10b when pulling the ferrule 10 out of the adapter 40 is 0.7 N or more. With this configuration, the lateral pressure on the ferrule 10 inserted and fitted into the adapter 40 is sufficiently large, making it possible to maintain good optical characteristics. For example, even if the ferrule 10 is repeatedly attached and detached to the adapter 40, deterioration of the positioning accuracy of the multiple optical fibers 20 is suppressed, making it possible to maintain good optical characteristics.

In addition, in the optical connection structure 100 according to this embodiment, the above-mentioned removal force of the ferrule 10 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 and the biasing force of the spring 30 when the ferrule 10 is inserted into the adapter 40 and butted against another ferrule 10. Conventionally, if the lateral pressure on the ferrule 10 inserted and fitted into the adapter 40 was too large, it could be difficult to remove the ferrule 10 from the adapter 40. However, according to the configuration of this embodiment, the removal force is of an appropriate magnitude, making it possible to easily remove the ferrule 10 from the adapter 40. As a result, user convenience is improved.

In the optical connection structure 100 according to this embodiment, the adapter 40 is made of resin and has a slit 42 formed in the first direction D1 from the first end 40a to the second end 40b opposite the first end 40a. In this case, when the ferrule 10 is inserted into the adapter 40, the adapter 40 is elastically deformed so that the width of the slit 42 increases, and a restoring force may be generated in the adapter 40 so that the width of the slit 42 decreases. This may generate lateral pressure on the ferrule 10 inserted into the adapter 40. As a result, it is possible to position multiple optical fibers 20 with a simple configuration without using guide pins or the like.

In addition, in the optical connection structure 100 according to this embodiment, the first side surface 13 and the second side surface 14 are provided with a first recess 23 and a second recess 24, respectively, and the first inner circumferential surface 43a and the second inner circumferential surface 44a are provided with a third protrusion 53 and a fourth protrusion 54, respectively, and in a cross section intersecting the first direction D1, the first recess 23 and the second recess 24 are each V-shaped, and in a cross section intersecting the first direction D1, the third protrusion 53 and the fourth protrusion 54 are each V-shaped. In this case, the ferrule 10 can be positioned with high precision relative to the adapter 40. In other words, the positioning of the multiple optical fibers 20 can be performed with high precision.

In the optical connector 1 according to this embodiment, the maximum force that pulls the ferrule 10 from the front end 10a toward the rear end 10b when pulling the ferrule 10 out of the adapter 40 is 0.7 N or more. With this configuration, the lateral pressure on the ferrule 10 inserted and mated into the adapter 40 becomes sufficiently large. As a result, an optical connection structure 100 that can maintain good optical characteristics can be realized.

In addition, in the optical connector 1 according to this embodiment, 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 and the biasing force of the spring 30 when the ferrule 10 is inserted into the adapter 40 and butted against another ferrule 10. In this case, the removal force is sufficiently small, making it possible to easily pull out the ferrule 10 from the adapter 40. As a result, user convenience is improved.

In the adapter 40 according to this embodiment, the maximum force that pulls the ferrule 10 from the front end 10a toward the rear end 10b when the ferrule 10 is pulled out of the adapter 40 is 0.7 N or more. With this configuration, the lateral pressure on the ferrule 10 inserted and fitted into the adapter 40 becomes sufficiently large. As a result, an optical connection structure that can maintain good optical characteristics can be realized.

In addition, the removal force of the adapter 40 according to this embodiment is 1.4 N or less. In this case, the removal force is sufficiently small, making it possible to easily pull out the ferrule 10 from the adapter 40. As a result, user convenience is improved.

The optical connection structure, optical connector, and adapter according to the present disclosure have been described in detail above, but the present invention is not limited to the above-described embodiments 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 diagram showing the cross-sectional shape of the 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 state in which the ferrule shown in FIG. 6 is held in the adapter shown in FIG. 5.

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 body 143, a second wall body 144, a third wall body 145, and a fourth wall body 146 as shown in FIG. 6. The first wall body 143 and the second wall body 144 form the short sides of a rectangle when viewed from the first direction D1. The first wall body 143 has a first inner peripheral surface 143a facing the first side surface 13 of the ferrule 10. The second wall body 144 has a second inner peripheral surface 144a facing the second side surface 14. The third wall body 145 has a third inner peripheral surface 145a facing the third side surface 15. The fourth wall 146 has a fourth inner circumferential surface 146a that faces the fourth side surface 16. In the example shown in FIG. 5 and FIG. 6, a slit 142 is formed in the third wall 145 that forms the third inner circumferential surface 145a. The slit 142 is formed from the first end 140a to the second end 140b in the first direction D1.

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 first inner peripheral surface 143a and the second inner peripheral surface 144a, respectively, by the first wall body 143 and the second 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 first inner circumferential surface 143a and the second 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 first inner circumferential surface 143a and the imaginary circle S that is 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 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 first inner circumferential surface 143a to the center of the virtual circle S tangent to the arc-shaped portion of the second inner circumferential 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 first side surface 13 and the second side surface 14 is the same as the diameter of the virtual 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 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 first side surface 13 and the second side surface 14 of the ferrule 10 by the restoring force when the cylindrical body 141 is elastically deformed.

In the above embodiment, the first side surface 13 and the second side surface 14 of the ferrule 10 are provided with the first recess 23 and the second recess 24, respectively, and the first inner circumferential surface 43a and the second inner circumferential surface 44a of the adapter 40 are provided with the third protrusion 53 and the fourth protrusion 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 third and fourth walls of the adapter are not depicted.

For example, as shown in FIG. 9, in the second modified example, the first side surface 13 and the second 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 first inner peripheral surface 43a and the second inner peripheral surface 44a of the adapter 40 may be provided with a third concave portion 253 and a fourth concave portion 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 concave portion 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.

Also, for example, as shown in FIG. 10, in the third modified example, the first side surface 13 and the second side surface 14 of the ferrule 10 may be provided with a first recess 323 and a second protrusion 324, respectively, and the first inner peripheral surface 43a and the second inner peripheral 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 the 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 the direction intersecting the first direction D1 is V-shaped with a top 353a at 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.

Also, for example, as shown in FIG. 11, in the fourth modified example, the first side surface 13 and the second 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 first inner peripheral surface 43a and the second 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.

12, in the fifth modified example, the first side surface 13 and the second side surface 14 of the ferrule 10 may have a first recess 523 and a second recess 524, respectively, and the first inner peripheral surface 43a and the second inner peripheral surface 44a of the adapter 40 may have a third protrusion 553 and a fourth protrusion 554, respectively. The first recess 523 and the second recess 524 may be formed in a groove shape, and the third protrusion 553 and the fourth protrusion 554 may be recessed inward 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. The cross-sectional shape of the third protrusion 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.

13, in the sixth modified example, the first side surface 13 and the second 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 first inner peripheral surface 43a and the second 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 recess 653 in a direction intersecting the first direction D1 has a U-shape curved with the same curvature as the first protrusion 623. The cross-sectional shape of the fourth protrusion 654 in a direction intersecting the first direction D1 has a U-shape curved with the same curvature as the second recess 624.

14, in the seventh modified example, the first side surface 13 and the second 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 first inner peripheral surface 43a and the second inner peripheral surface 44a of the adapter 40 may be provided with a third concave portion 753 and a fourth concave portion 754, respectively. The first convex portion 723 and the second convex portion 724 may protrude outward in the second direction, and the third concave portion 753 and the fourth concave 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.

Furthermore, 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.

1...optical connector 10...ferrule 10a...front end 10b...rear end 11...optical end surface 12...rear end surface 12a...projection 13...first side surface 14...second side surface 15...third side surface 16...fourth side surface 17...opening 18...retaining hole 20...optical fiber 23...first recess 23a...slope 23b...slope 23c...bottom 24...second recess 24a...slope 24b...slope 24c...bottom 30...spring 40...adapter 40a...first end 40b...second end 41...cylindrical body 42...slit 43...first wall Body 43a...first inner circumferential surface 44...second wall 44a...second inner circumferential surface 45...third wall 45a...third inner circumferential surface 45A...first portion 45B...second portion 46...fourth wall 46a...fourth inner circumferential surface 53...third convex portion 53a...inclined surface 53b...inclined surface 53c...tip 54...fourth convex portion 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 142...slit 143...first wall 143a...first inner circumferential surface 144...second wall 144a...second inner circumferential surface 145...third wall 145a...third inner circumferential surface 146...fourth wall 146a...fourth 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 42 4...second convex portion 453...third concave portion 454...fourth concave portion 523...first concave portion 524...second concave portion 553...third convex portion 554...fourth convex portion 623...first convex portion 624...second concave portion 653...third concave portion 654...fourth convex portion 723...first convex portion 724...second convex portion 753...third concave portion 754...fourth concave portion 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 optical connector including: a plurality of optical fibers; a ferrule that holds the plurality of optical fibers and has a front end and a rear end opposite the front end; and a spring that biases the ferrule from the rear end toward the front end;
an adapter having a cylindrical shape and configured to have the optical connector inserted therein and fitted thereto such that the ferrule and another ferrule face each other inside the cylindrical shape;
Equipped with
The ferrule has a first side and a second side facing each other,
The first side surface is provided with a first recess or a first protrusion extending along a first direction in which the optical connector is inserted into the adapter,
The second side surface is provided with a second recess or a second protrusion extending along the first direction,
an inner surface of the adapter is provided with a third convex portion or a third concave portion that can be fitted with the first concave portion or the first convex portion, and a fourth convex portion or a fourth concave portion that can be fitted with the second concave portion or the second convex portion,
An optical connection structure, wherein a removal force, which is a maximum value of a force pulling the ferrule from the front end toward the rear end when the ferrule is pulled out of the adapter, is 0.7 N or more. The optical connection structure according to claim 1, wherein the removal force is equal to or less than the difference between the biasing force of the spring when the optical connector is not inserted into the adapter and the biasing force of the spring when the optical connector is inserted into the adapter and butted against the other ferrule. The optical connection structure according to claim 1 or 2, wherein the adapter is made of resin and has a slit formed in the first direction from a first end to a second end opposite the first end. The first side surface and the second side surface are provided with the first recess and the second recess, respectively;
the third protrusion and the fourth protrusion are provided on an inner surface of the adapter,
In a cross section intersecting the first direction, the first recess and the second recess are each V-shaped,
3 . The optical connection structure according to claim 1 , wherein the third convex portion and the fourth convex portion are each V-shaped in a cross section intersecting the first direction. A plurality of optical fibers;
a ferrule for holding the plurality of optical fibers and having a front end and a rear end opposite the front end;
a spring that biases the ferrule from the rear end toward the front end,
The ferrule is configured to be insertable into and removable from a cylindrical adapter, and has a first side surface and a second side surface opposed to each other,
the first side surface is provided with a first recess or a first protrusion extending along a first direction in which the ferrule is inserted into the adapter,
The second side surface is provided with a second recess or a second protrusion extending along the first direction,
an extraction force, which is a maximum value of a force pulling the ferrule from the front end toward the rear end when the ferrule is pulled out of the adapter, is 0.7 N or more. The optical connector according to claim 5, wherein the removal force is equal to or less than the difference between the biasing force of the spring when the ferrule is not inserted into the adapter and the biasing force of the spring when the ferrule is inserted into the adapter and butted against another ferrule. a cylindrical body having a cylindrical shape and configured so that a ferrule having a front end and a rear end opposite to the front end can be inserted into and removed from the cylindrical body;
a third convex portion or a third concave portion, and a fourth convex portion or a fourth concave portion are provided on an inner surface of the cylindrical body,
an extraction force, which is the maximum value of the force pulling the ferrule from the front end toward the rear end when pulling the ferrule out of the cylindrical body, is 0.7 N or more. The adapter according to claim 7, wherein the removal force is 1.4 N or less.

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